O O B-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O B-Wavelength O B-Wavelength B-Wavelength O B-Wavelength O O B-Wavelength O B-Wavelength B-Wavelength O B-Wavelength O O O O B-Telescope O B-Telescope O O B-Location O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O B-Telescope O B-Observatory O O O O O B-CelestialObject I-CelestialObject O B-Wavelength O O B-CelestialObject O O O O O B-Proposal O O O O O O O O O O B-Telescope I-Telescope I-Telescope I-Telescope B-Telescope B-Citation I-Citation I-Citation I-Citation O O O O O O O O O B-Instrument I-Instrument I-Instrument B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength O O O B-Wavelength I-Wavelength O O O O O O O O O O O O O B-Software O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O O O O O O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O B-Wavelength O O O O O O B-Wavelength O B-Wavelength O O O O O B-Telescope O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O

ratio of Y e = 0.30, for the assumed distance of 40 Mpc. We also present photometry of AT 2017gfo over a period 10 d post detection, in optical ( B, V and R ) and infrared ( J, H and K ), derived from the MASTER-SAAO and IRSF telescopes at Sutherland, respectively. We again compare these results to the respective kilonova model predictions, and conclude that either the Y e = 0.25 or 0.30 wind models are qualitatively similar to the observed magnitudes. 2 SALT AND SAAO OBSERVATIONS Following the detection of AT 2017gfo, the optical counterpart to GW170817, director’s discretionary time observations (programme 2017-1-DDT-009) were undertaken on 2017 August 18 and 19 on the Southern African Large Telescope (SALT; Buckley et al. 2006 ). The observations were taken with the prime focus Robert Stobie spectrograph (Burgh et al. 2003 ), beginning in twilight and proceeding until the end of the available telescope track time. A third attempt on August 20 resulted in no meaningful data being obtained due to the sky brightness coupled with the degree of fading of the kilonova. The observational details are included in Table 1 , and preliminary reports on the results are presented in Shara et al. ( 2017 ), Abbott et al. ( 2017b ), McCully et al. ( 2017 ) and Andreoni et al. ( 2017 ). Table 1. Observing details. Notes. a Transparency; seeing. b Since GW trigger time: 2017 August 17, 12h41m04s UTC. The low-resolution PG300 surface relief transmission grating was used, rotated to an angle of 5.75°, with a long slit of width 2 arcsec, which implies an ∼88 per cent slit throughput in the given seeing conditions. The spectra had a resolution which varied from R ∼ 150 (at ∼3750 Å) to ∼400 (at ∼9600 Å), with a mean of R ∼ 380. The observations were reduced using the PySALT package (Crawford et al. 2010 ), which accounts for basic CCD characteristics (cross-talk, bias and gain correction) and removal of cosmic rays, wavelength calibration, and relative flux calibration. Additional reductions to account for accurate sky and galaxy background removal were done using standard iraf routines. Because of the SALT design, which has a moving, field-dependent and underfilled entrance pupil, absolute flux calibration with SALT is difficult to achieve with a good degree of accuracy, which at best is ± 20 per cent. Observations were taken in morning twilight on 2017 August 18 of the spectrophotometric standard star EG21, which was used to determine a relative flux calibration on both nights. The spectral fluxes were then corrected by convolving the observed spectra with standard Johnson–Cousins B and R filters and comparing the results with B and R observations taken simultaneously with the MASTER-SAAO facility, which are included in Table 1 , corrected for Milky Way extinction, as presented in Lipunov et al. ( 2017 ). This comparison implied that the spectra were required to be adjusted in flux by a multiplicative constant of 2.04 and 2.4, respectively, on the


O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O B-Model I-Model O O O O O O O O O O O O O O O O O O B-Citation I-Citation O B-Citation O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O B-Model I-Model I-Model O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O B-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O

The stopping time is a measure of the timescale on which the gas transfers its angular momentum to dust and can be expressed as (Perets Murray-Clay 2011 )where is the gas thermal velocity, R s is the radius of the solid particle, ρ s is its density, assumed to be 1 g cm −3 regardless of the size, and v rel is the relative velocity between the gas and the dust grain. The dimensionless drag coefficient C D is a function of the Reynolds number Re of the flow around the particle and derives from an empirical law fitted on recent experimental data (Perets Murray-Clay 2011 ):where Re is the Reynolds number. It is given by (Supulver Lin 2000 )where l g is the mean-free path of the gas. The turbulent diffusion of the grains is modeled using a Monte-Carlo scheme where individual particles are given random impulses to mimic the stochastic transport due to turbulent eddies (see, e.g., Ciesla 2010 , 2011 ). Overall, the new position z d of a dust grain after a timestep dt is computed as follows in the vertical direction:where R 1 ∈ [−1; 1] is a random number, σ 2 is the variance of the random number distribution, D p is the diffusivity of the solid particle, and v adv is the term accounting for the nonuniform density of the gas in which the particles diffuse as well as the nonuniform diffusivity of the particles, and the forces experienced by the particle (see Equation ( 11 )). The diffusivity of the dust grains D p is related to the gas diffusivity through the Schmidt number Sc as (Youdin Lithwick 2007 ):where ν = αH 2 g Ω K is the turbulent viscosity of the gas (assumed to be equivalent to the gas diffusivity) expressed through the nondimensional α parameter measuring the level of turbulence within the disk (Shakura Sunyaev 1973 ) and St is the Stokes number, corresponding to the stopping time multiplied by the local Keplerian frequency. Larger values of α yield a more efficient redistribution of the dust grains through turbulent diffusion. Finally, the advection term in the transport equation is given by Ciesla ( 2010 , 2011 ) as This set of equations allows us to derive the vertical position z d of individual particles at each timestep and to subsequently estimate the dose of irradiation they received. 3. Irradiation of Grains The energy received by water molecules per unit time due to cosmic-ray irradiation W irr ( n ) as a function of the column density of gas n above the particle is taken from Yeghikyan ( 2011 ). These authors computed this term by using the cosmic-ray intensity I ( E ) (cm −2 s −1 st −1 MeV −1 ) from Cooper et al. ( 2003 ) and considering a planar geometry. This leads to a differential flux spectrum inside the disk F ( E ) given by W irr ( n ) is then derived from the molecular cloud material stopping power S ( E ), i.e., its capability to absorb the cosmic-ray energy, as estimated from the Stopping and Range of Ions in Matter program (Ziegler et al. 2010 ). Note that the stopping power mostly depends on the mass density and not


O O O O O O O B-Model I-Model I-Model I-Model I-Model I-Model I-Model O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O B-Citation I-Citation I-Citation I-Citation O O O O O B-Model I-Model O O O O O O O O O B-Model I-Model O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model I-Model O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O B-Model I-Model O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O B-CelestialObjectRegion O B-CelestialObjectRegion O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation O O O O O O B-Model I-Model O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O O B-Formula I-Formula I-Formula I-Formula O O O O B-Formula I-Formula I-Formula I-Formula O O B-Model I-Model O O O B-CelestialObject I-CelestialObject O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula O B-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation O B-Citation O O O O O O O O O O O O O O O O O

the closure relations are determined by the Klein and Tolman conditions of thermodynamic equilibrium ( Ruffini et al. 2015 ). The solution to this system of equations leads to a continuous and novel dense core – diluted halo DM profile from the center all the way to the galactic halo (see Siutsou et al. 2015 ; Argüelles et al. 2016 ; Mavromatos et al. 2017 , for its applications). Similar core-halo profiles with applications to fermionic DM were also obtained in Bilic et al. (2002) and more recently in Chavanis et al. (2015) from a statistical approach within Newtonian gravity. The above corresponds to the original version of the RAR model, with a unique family of density profile solutions that behaves as ρ ( r )∝ r −2 at large radial distances from the center. This treatment was extended in Argüelles et al. (2018) , by introducing a cutoff in momentum space in the distribution function (DF; i.e., accounting for particle-escape effects) that allows defining the galaxy border (see Appendix A ). This extension of the RAR model was successfully applied to explain the Milky Way rotation curve, as shown in Fig. 1 , implying a more general dense core – diluted halo behavior for the DM distribution as follows: Fig. 1. Milky Way rotation curve and DM density profile from the extended RAR model with a core mass of M c = M ( r c ) = 3.5 × 10 6 M ⊙ . Top : DM (black) and baryonic (bulge + disk) contribution to the rotation curve v rot (total in red). Bottom : DM density profile. The baryonic model and the data are taken from Sofue (2013) . The parameters of the extended RAR model in this case are fermion mass m c 2 = 56 keV, temperature parameter β 0 = 1.1977 × 10 −5 , degeneracy parameter θ 0 = 37.7656, and energy cutoff parameter W 0 = 66.3407. For the RAR model fitting of the Milky Way, we follow Argüelles et al. (2018) ; see also Appendix A . – A DM core with radius r c (defined at the first maximum of the twice-peaked rotation curve), whose value is shown to be inversely proportional to the particle mass m , in which the density is nearly uniform. This central core is supported against gravity by the fermion degeneracy pressure, and general relativistic effects are appreciable. – Then, there is an intermediate region characterized by a sharply decreasing density where quantum corrections are still important, followed by an extended and diluted plateau. This region extends until the halo scale-length r h is achieved (defined at the second maximum of the rotation curve). – Finally, the DM density reaches a Boltzmann regime supported by thermal pressure with negligible general relativistic effects, and shows a behavior ρ ∝ r − n with n > 2 that is due to the phase-space distribution cutof. This leads to a DM halo bounded in radius (i.e., ρ ≈ 0 occurs when the particle escape energy approaches zero). As was explicitly shown in Argüelles et al. (2019b , a , 2018) , this type of dense core – diluted halo density profile suggests that the DM might explain


O O O O B-Survey I-Survey O O O O O B-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization O B-Location O B-Organization I-Organization I-Organization I-Organization I-Organization O O B-Location I-Location O B-Organization I-Organization I-Organization I-Organization O B-Location O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization O B-Organization I-Organization O O O O O O B-Survey I-Survey I-Survey O O O O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization O B-Collaboration I-Collaboration O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization B-Organization B-Location B-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O O O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O B-Observatory I-Observatory I-Observatory I-Observatory O B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization B-Organization I-Organization O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O B-Survey O O O O O O O B-Organization I-Organization I-Organization O O O B-Grant O B-Survey O O B-Location O O O O O B-Organization O O B-Grant B-Grant B-Grant O B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant O O O O O O O O O O B-Organization I-Organization I-Organization O O B-Location I-Location B-Grant I-Grant I-Grant B-Grant O B-Organization O O B-Grant B-Grant O B-Grant O O O O O O O O O B-Observatory O O O B-Instrument B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Organization I-Organization I-Organization I-Organization

Acknowledgments Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas AM University, Financiadora de Estudos e Projetos, Fundao Carlos Chagas Filho de Amparo Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cientfico e Tecnolgico and the Ministrio da Cincia, Tecnologia e Inovao, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energticas, Medioambientales y Tecnolgicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenssische Technische Hochschule (ETH) Zrich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Cincies de lEspai (IEEC/CSIC), the Institut de Fsica dAltes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universitt Mnchen and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex and Texas AM University. The DES data management system is supported by the National Science Foundation under grant number AST-1138766. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2012-39559, ESP2013-48274, FPA2013-47986 and Centro de Excelencia Severo Ochoa SEV-2012-0234. Research leading to these results has received funding from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007-2013) including ERC grant agreements 240672, 291329 and 306478. We are grateful for the extraordinary contributions of our CTIO colleagues and the DECam Construction, Commissioning and Science Verification teams in achieving the excellent instrument and telescope conditions that have made this work possible. The success of this project also relies critically on the expertise and dedication of the DES Data Management group.


O B-Dataset I-Dataset O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model I-Model I-Model I-Model O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O B-Model I-Model I-Model I-Model O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O B-Model I-Model I-Model O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Survey O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

in Kharchenko’s catalog and count the summed flux of member stars inside-out until the radius where the flux is half of the total. We also use the bootstrap realizations to estimate the error in r h . Here, not all the member stars but only the visible ones are used for the calculation of r h . The mass segregation effect (Pang et al. 2013 ) might bias the r h we measure. To test this effect, we also count the half-number radius, the radius where the number of most probable member stars is half the total, and find that it is almost indistinguishable from the r h of each OC. The error of r h is quite small at the order of 0.01–0.05 pc. 3.2. The Line-of-sight Velocity Dispersion The accuracy of RVs allows us to compute the line-of-sight velocity dispersion ( σ 1D ) among member stars. We use stars having high S/N and RV errors less than 0.125 km s −1 . Typically, these stars of high S/N also have [Fe/H] measurements. To further reduce possible biases from membership determination, we fit the [Fe/H] and RV distribution with a two-dimensional Gaussian mixture model Φ tot , which is constituted of two components, the cluster Φ c and the field Φ f . Under this assumption, the likelihood of a star with given parameters is , where n c is the fraction of the cluster component; is Gaussian distribution function; , , and are the dispersions of ; RV c (RV f ) is the mean RV of cluster (field); and M c ( M f ) is the mean metallicity of cluster (field), respectively. Note that and are not constants, but are composed of two terms, the intrinsic dispersion () and the individual observational uncertainty (), which varies by one star: Parameters are fitted so that the total likelihood of all stars reaches maximum. We use nested sampling to derive the probability density function (PDF) of parameters. Since the resulting PDF is almost Gaussian, we take the mean and standard deviation of the PDF, as the best estimation of the parameters and their errors. As an example in Figure 2 , the blue dots show the [Fe/H] and RV values for individual selected stars in NGC 1245, where the two-dimensional Gaussian mixture model (Equation ( 1 )) is projected into one-dimension to show how well the model fits the data. The [Fe/H]–RV distribution is fitted well by the sum of field (green lines) and member (red lines) components. Figure 2. Distribution of [Fe/H] and RV (blue dots) for the open cluster NGC 1245 is fitted with a two-dimensional Gaussian model. For illustration, we project this model into one-dimension. The distributions of [Fe/H] (right histogram) and RV (top histogram) are constituted of two components, the field (green lines) and the cluster (red lines). The histogram is normalized such that the integral over the range is 1. The members of OCs observed in APOGEE-2 are spatially random sampling of the OC members. Therefore, we do not expect that this random member list will bias the computation of the velocity dispersion of OCs. Typically, the RV measurements of


O O O O O O O O O O O O O O B-Person I-Person O O O O O O O O O O B-Organization I-Organization I-Organization B-Organization O O B-Location I-Location B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant O O O B-Grant B-Grant B-Person O O O O O B-Organization I-Organization O O B-Fellowship I-Fellowship I-Fellowship I-Fellowship I-Fellowship O O B-Organization I-Organization I-Organization B-Location B-Person O O O O B-Organization I-Organization O O B-Grant

ACKNOWLEDGEMENTS The authors would like to thank the referee for their comprehensive review and Andrea Ravenni for useful discussions. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 725456; CMBSPEC). JC was also supported by the Royal Society as a Royal Society University Research Fellow at the University of Manchester, UK. EL was supported by the Royal Society on grant NoRGF/EA/180053.


B-Person O B-Person I-Person O O O B-Telescope O O B-CelestialObject O O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O B-Grant I-Grant O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O B-Grant I-Grant O B-Grant O O O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O O B-Observatory I-Observatory I-Observatory B-Organization I-Organization I-Organization I-Organization O O B-ComputingFacility I-ComputingFacility

J.R. acknowledges Dr. Aoki for providing the Subaru spectrum for G64-12. This research was supported by the National Key Basic Research Program of China under grant No. 2014CB845700 and the National Natural Science Foundation of China under grants No. 11473033 and 11603037. This work is also supported by the Astronomical Big Data Joint Research Center, co-founded by the National Astronomical Observatories, Chinese Academy of Sciences and the Alibaba Cloud.


O O O O O O O O B-CelestialObjectRegion O O O O O O O B-Observatory B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O B-Wavelength I-Wavelength O O O B-Observatory B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O B-CelestialObjectRegion O O O B-Wavelength O B-Wavelength O B-Observatory B-Telescope O B-Observatory B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O B-Wavelength O B-Wavelength I-Wavelength O O O O O O O O O O O O O B-Observatory B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObjectRegion O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O B-CelestialObjectRegion O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O

traveling intensity perturbation of a hot, 8–10 MK, coronal loop, in a C7.4 class flare, with SDO /AIA. The intensity variation was seen to bounce approximately four times between the loop’s footpoints, before fading, i.e., exhibiting a “zigzag” pattern in a time–distance plot made along the apparent direction of the magnetic field. The oscillation period and decay time were about 630 s and 440 s, respectively. The apparent phase speed was about 460–510 km s −1 which matched the sound speed in the loop. The authors suggested calling this phenomenon a reflecting longitudinal wave, while Reale ( 2016 ) introduced the term “sloshing” oscillations for this phenomenon. A similar, bouncing back and forth between the footpoints, EUV intensity perturbation was detected in another C-class flare by Kumar et al. ( 2015 ). The period of the oscillation and decay time were about 409 s and 1121 s, respectively. The characteristic phase speed of the wave is about 560 km s −1 , which was roughly consistent with the sound speed at the temperature of about 10–16 MK. Wang et al. ( 2015 ) observed a clear sloshing pattern in the 131 Å intensity oscillation with SDO /AIA. The oscillation period, decay time, and the apparent phase speed were estimated as about 12 minutes, 9 minutes, and 500 km s −1 , respectively. Mandal et al. ( 2016 ) reported a simultaneous observation of a propagating and reflecting intensity disturbance in a hot coronal loop observed in EUV and X-rays with SDO /AIA and Hinode /XRT, respectively. In addition, three other cases of intensity pulses sloshing between footpoints were analyzed. In all considered cases the projected traveling speed was found to be lower than the local sound speed, consistent with the slow wave interpretation. Pant et al. ( 2017 ) observed antiphase oscillations of the 171 and 193 Å intensity oscillations at two ends of a nonflaring fan loop system observed with SDO /AIA. The oscillation period was estimated to be 27 minutes, the damping time of 45 minutes, and the apparent phase speed of about 75 km s −1 . The time–distance map made along the loop showed a sloshing (i.e., “zigzagging”) motion pattern. We need to point out that sloshing oscillations are different from other manifestations of slow waves in the corona, propagating (not reflecting) slow waves that are detected in polar plumes and near footpoints of long loops (see, e.g., de Moortel 2009 ). Numerical modeling of slow oscillations in a coronal loop reproduced main properties of standing (SUMER) and sloshing oscillations, i.e., the observed oscillation period, P slow ≈ 2 L / C s , where L is the loop length and C s is the sound speed; and associated the rapid damping of the oscillation with the effect of thermal conduction (Ofman Wang 2002 ). Nakariakov Zimovets ( 2011 ) demonstrated that a similar periodicity could occur in arcades. The preferential excitation of lower, i.e., the fundamental and second parallel harmonics by an impulsive source, was found


O O O O O B-Organization I-Organization O B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant B-Person O O O O B-Grant I-Grant I-Grant I-Grant O B-Telescope O O O O B-Organization O O B-Organization I-Organization I-Organization O O O O O O B-ComputingFacility I-ComputingFacility I-ComputingFacility I-ComputingFacility I-ComputingFacility O O O B-Organization I-Organization I-Organization B-Person O B-Person O O B-Organization I-Organization I-Organization I-Organization O O O O O O O B-Person O B-Person O O O O B-Person O O O O O O O O O O O O O B-Person O O O O O O O O O O O O O O O B-Person I-Person O B-Person I-Person O O O O O O O

This work was supported by NYUAD Institute Grant G1502 “NYUAD Center for Space Science”. RA acknowledges support from the NYUAD Kawadar Research Program. The HMI data is courtesy of NASA/SDO and the HMI Science Team. Computational resources were provided by the German Data Center for SDO funded by the German Aerospace Center. SMH and LG thank the Max Planck partner group program for supporting this work. Author contributions: CSH and LG designed the research goals. RA proposed the machine-learning methodology for predicting flows and performed experimental and computational analysis. CSH prepared data and performed helioseismic analysis. All authors contributed to the final manuscript. We thank Aaron Birch and Bastian Proxauf for helpful insight into the ring-diagram pipeline.


O O O O O O B-Person I-Person O O O O O O O O O O O O O O O B-ComputingFacility I-ComputingFacility O O B-ComputingFacility I-ComputingFacility I-ComputingFacility I-ComputingFacility I-ComputingFacility I-ComputingFacility B-ComputingFacility O B-Location O B-Location B-Person O B-Person O O O O B-Grant I-Grant B-Grant I-Grant B-Grant O O B-Organization I-Organization I-Organization

ACKNOWLEDGEMENTS We would like to thank Anz̆e Slosar for useful comments and discussions. The simulations used in this work were run on the Cobra supercomputer at the Max Planck Computing and Data Facility (MPCDF) in Garching near Munich. AB and FS acknowledge support from the Starting Grant (ERC-2015-STG 678652) ’GrInflaGal’ of the European Research Council.


O O O B-CelestialObject O O O O O O O O O O O O O O O B-CelestialObjectRegion I-CelestialObjectRegion O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O B-Citation I-Citation O O O O O O O O O O B-Model I-Model O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O B-Citation I-Citation I-Citation I-Citation I-Citation O B-Citation O O O O O O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObjectRegion I-CelestialObjectRegion O B-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model I-Model I-Model O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

by an analytic MW potential, as well as to resolve analytically the interaction between the dwarf gas and the MW halo gas. The gas removal from dwarf galaxies is analytically calculated using the Close et al. ( 2013 ) model, for which two physical processes are considered, i.e., the balance between the gravitational force of the dwarf galaxy and the external ram pressure (i.e., from the Gunn Gott 1972 formula), and the mass loss introduced by Kelvin–Helmholtz instabilities (e.g., Nulsen 1982 ). We have verified that the above technique of “pure N -body for stars plus analytical ram pressure for gas” is able to reproduce the gas removal process resolved by hydrodynamics simulations done in Yang et al. ( 2014 ) and in Hammer et al. ( 2018 , 2019 ). The above allows us to probe the interaction of dSph stars with the MW gravitational field in a full Newtonian scheme. By adopting a gravitational force softening of 0.005 pc, it implies that there should be no stellar particles that can be affected by the undesirable effects due to the softening in media with central stellar density ∼500 times smaller than at the Sun neighborhood (see H19 ). From left to right, Figure 4 shows three different steps in evolution of such a stellar system after the gas removal, i.e., when it may resemble a dSph. It includes (1) when the gas has just been fully removed, (2) just after pericenter at the peak of tidal shock effects, and (3) well after pericenter, when the system almost vanishes owing to the heavy tidal stripping process that unavoidably follows tidal shocks. Figure 4. Summary of two N -body simulations of a DM-free and gas-rich dSph progenitor, with three columns on the left (right) for model C (model Q), respectively. They are shown at steps 1, 2, and (3), from left to right, respectively (see text). The first line shows the appearance of the simulated galaxies in gray colors. For other lines, green, red, black, and gray symbols represent stars in step 1, from very low velocity and very near the center to very high velocity and very far from the center (gray symbols with extremely low density); see left panels of the (d)–(f) rows. From top to bottom: (a) projected view on sky; (b) V los vs. sky projected radius, with the vertical blue dashed line showing r half that includes the selected stars; (c) the evolution of σ los with time showing a peak very near the pericenter passage (see point in middle panel), and with the gray curve indicating the theoretical expectation from Equation ( 5 ) for f MW shocks = 0.25 (0.08) for model C (model Q), which also includes self-gravity from gas and stars; (d) the velocity distribution projected in gal-( Y , Z ) plane in Galactocentric coordinates, and with the arrow showing the MW direction; (e) the phase diagram indicating that many stars are leaving the system after gas removal (left panel); and (f) V los vs. showing that near pericenter (middle panel) most stars have their motions only on the line of sight. In Figure


O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

other two levels 2s2p 2 2 P 1/2 and 2s 23 d 2 D 3/2 . Fig. B.6. Same as Fig. B.1 but for four Fe XXII lines. The R -matrix data from Liang et al. (2012) are plotted in red. The R -matrix calculation of electron-impact excitation of Fe XXIII was made by Fernández-Menchero et al. (2014) , based on 238 fine-structure levels in both the configuration interaction target and close-coupling collision expansions. We compare the collision strengths for four strong Fe XXIII lines with their calculations, on which the resonance has a large effect. As shown in Fig. B.7 , the two sets of data agree very well within a difference of ≤5% for T e = 0.1 − 10 keV. Fig. B.7. Same as Fig. B.1 but for four Fe XXIII lines. The R -matrix data from Fernández-Menchero et al. (2014) are shown in red. In Fig. B.8 we compare our calculations of the total excitation of four main Fe XXIV lines with the R -matrix results reported in Liang Badnell (2011) . The R -matrix work was done with the intermediate coupling frame transformation method for 195 levels, and the Auger- as well as radiation-damping effects were both taken into account. For 3s 2 S 1/2 , 3d 2 D 3/2 , and 3d 2 D 5/2 , the R -matrix and our data agree well with ∼5%, while for 3p 2 P 3/2 , the difference between the two approaches becomes slightly larger, ∼10%, for the collision strengths at energy of ≤1 keV. Fig. B.8. Same as Fig. B.1 but for four Fe XXIV lines. The R -matrix data from Liang Badnell (2011) are plotted in red. The illustrative comparison indicates that the difference between the modern large-scale isolated resonance calculation and the recent interacting R -matrix becomes now smaller than previously reported in Badnell et al. (1994) . The two methods are well within 20% for the direct transitions from the ground states to a few selected excited levels at n = 3. As shown in Fig. 6 , some excited levels are heavily populated through cascade, indicating that the line intensities could actually be significantly affected by the excitation rate coefficients to higher states. In the following section, we will give an extensive comparison for all the relevant rates. B.3. Comparing with recent R-matrix results: Scatter plots The scatter plot in Fig. B.9 shows the comparison of the effective collision strengths from the current and R -matrix calculations, for all the excitations from the ground states. The R -matrix results are a collection of the works mentioned in Appendix B.2 . The plot confirms that the two methods agree on the strongest transitions within uncertainties of ∼20%. However, the discrepancies between the two methods on the weaker transitions are substantially larger, up to a factor of two for Fe XVII and Fe XXIV , and one order of magnitude for the rest ions, at the lowest effective collision strengths. We note that orders of magnitude difference for weak transitions are also found among different R -matrix calculations (intermediate coupling frame transformation, Breit-Pauli, Dirac atomic


O B-Organization I-Organization I-Organization O B-Organization O O O O O O B-Organization O O B-Grant O O B-Organization O O B-Grant O O O O O O O O O B-Organization I-Organization I-Organization B-Fellowship I-Fellowship I-Fellowship I-Fellowship O O O B-Fellowship O O B-Person I-Person O B-Person I-Person O O O O O O B-Telescope I-Telescope I-Telescope O O O B-Person I-Person O B-Person I-Person O O O O O O B-Telescope O O O O O O O O O O O O B-Observatory I-Observatory O O B-Organization I-Organization B-Organization I-Organization B-Organization I-Organization I-Organization B-Organization I-Organization O O B-Organization I-Organization I-Organization O O O O O O O O O O B-Grant I-Grant I-Grant I-Grant O B-Person B-Person O O O O O O B-Grant O O B-Organization O B-Grant I-Grant I-Grant I-Grant O O O O O B-Proposal O O O B-Observatory I-Observatory O O O B-Archive I-Archive I-Archive O O O O B-Software I-Software I-Software O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O O O O O B-Organization O O O O B-Observatory O O B-Organization I-Organization I-Organization B-Location I-Location O B-Organization I-Organization I-Organization B-Location B-Organization B-Location B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Location O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Location O O O O O O O O B-Organization I-Organization I-Organization I-Organization O O O B-Observatory I-Observatory I-Observatory O O O O O O O O B-Observatory I-Observatory O O O O O B-Organization I-Organization O O B-Organization I-Organization I-Organization O O O O O O O B-Telescope I-Telescope I-Telescope I-Telescope O O B-Observatory I-Observatory I-Observatory B-Location O O O O O O B-Organization B-Telescope I-Telescope I-Telescope O O O O O O O O B-Organization I-Organization I-Organization I-Organization O O O B-Grant O O O B-Organization O O O O O B-Organization I-Organization I-Organization I-Organization O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization O B-Grant I-Grant

The Berger Time-Domain Group at Harvard is supported in part by the NSF under grant AST-1714498 and by NASA under grant NNX15AE50G. This paper is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE1144152. We thank Pete Challis and Allyson Bieryla for assistance with some of the FLWO 48 inch observations. We thank Stephen Smartt and Ken Smith for providing access to the early PSST images. This work is based in part on observations obtained at the MDM Observatory, operated by Dartmouth College, Columbia University, Ohio State University, Ohio University, and the University of Michigan. This work is partially based on data acquired with the Swift GO program 1114109 (PI Margutti). R.M. acknowledges partial support from programs No. NNX16AT51G provided by NASA through Swift Guest Investigator Programs. Based on observations (Proposal ID GN-2016B-FT-28) obtained at the Gemini Observatory acquired through the Gemini Observatory Archive and processed using the Gemini IRAF package, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil). This paper uses data products produced by the OIR Telescope Data Center, supported by the Smithsonian Astrophysical Observatory. Some observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Based on observations made with the NASA/ESA Hubble Space Telescope , obtained from the data archive at the Space Telescope Science Institute. Support for program GO-15162 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.


We thank Gijs Nelemans for useful discussions.


B-Person O B-Person I-Person I-Person B-Person I-Person B-Person I-Person B-Person I-Person B-Person I-Person B-Person I-Person O B-Person I-Person O O O O O O O O O O O O B-Telescope O O O B-Location B-Observatory I-Observatory I-Observatory I-Observatory I-Observatory I-Observatory O O B-Organization I-Organization I-Organization I-Organization I-Organization O O B-Location I-Location I-Location I-Location O O O O O O O O B-Database O O O O O B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization O O O O B-Organization I-Organization I-Organization I-Organization I-Organization O O O O O O B-Software O O O O O O B-Software O O B-URL O B-Archive I-Archive I-Archive I-Archive O B-Software O O O O O O B-Observatory I-Observatory I-Observatory I-Observatory O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Organization O O O O O B-Organization I-Organization I-Organization O B-Organization O O O O O O B-Location B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization O O B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant B-Person O B-Person O O O O O B-Organization I-Organization I-Organization I-Organization O B-Location O B-Grant I-Grant B-Person O O O O B-Grant O O B-Location B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization

MAB thanks Tomas Ruiz Lara, Mina Koleva, Ryan Leaman, John Beckman, Chris Flynn, Bradley Gibson and Marie Martig for useful discussions. This paper is based on observations made with the GTC, installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma. This research has made extensive use of the NED which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research also made use of aplpy , an open-source plotting package for python hosted at http://aplpy.github.com , NASA's Astrophysics Data System and iraf , which is distributed by the National Optical Astronomy Observatory and operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation. The IAC researchers acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under the 2011 Severo Ochoa Program MINECO SEV-2011-0187. CG and AA are partially funded by the Science and technology Ministry of Spain (grant AYA 2010-16717). MB acknowledges support from grant AYA2013-48226-C3-1-P from the Spanish Ministry of Economy and Competitiveness (MINECO).


O O O O B-Person I-Person B-Person I-Person B-Person I-Person O B-Person I-Person O O O B-Person O O O O O O O O B-Person I-Person O B-Person I-Person B-Person O O O O B-Fellowship I-Fellowship I-Fellowship I-Fellowship I-Fellowship O O O O O O O B-ComputingFacility I-ComputingFacility O O B-Organization I-Organization I-Organization I-Organization O O B-Person I-Person O O O O O O O O O O O O O O B-ComputingFacility I-ComputingFacility O O O B-ComputingFacility O O B-Grant I-Grant O O O O O O B-Software O O O O O O O O O O O O O O O O O O O

We wish to thank J. Blaizot, J. Devriendt, R. Teyssier and M. Trebitsch for useful suggestions. CC wishes to acknowledge the valuable feedback provided by R. Beckmann and P. Mitchell. CC is sponsored by the Institut Lagrange de Paris fellowship. This work has made use of the Horizon Cluster hosted by Institut d’Astrophysique de Paris. We thank Stephane Rouberol for running smoothly this cluster for us. It has also made use of the Occigen Cluster hosted by the CINES on the A0040406955 GENCI grant. This work has extensively used YT , the open-source analysis and visualisation toolkit. The source code of the new tracer particles is available upon request.


O O O O O O O O O O O O O O O B-EntityOfFutureInterest O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O B-CelestialObject O O O O O O O O O O O O O B-EntityOfFutureInterest O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation O B-Citation I-Citation I-Citation O O O O O O O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation O O O O O O O B-Citation I-Citation O B-Citation I-Citation I-Citation O O O O O O B-EntityOfFutureInterest O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model B-Citation I-Citation I-Citation O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O B-Survey I-Survey I-Survey I-Survey I-Survey I-Survey I-Survey I-Survey B-Survey B-Citation I-Citation I-Citation O B-Survey O O O O O O O O B-Survey B-Survey O O B-EntityOfFutureInterest O O O O O O O

of a desert beyond. However, of the 382 stars in their sample, only 36 are solar-type (main-sequence with 5000 T eff 6000K) stars. Troup etal. ( 2016 ) argue that this result agrees with the work of Guillot etal. ( 2014 ) who find that the BD desert may not be as dry as initially thought when considering stars more massive than the Sun, as well as evidence that the BD desert is a special case for solar-mass stars (Duchne Kraus 2013 ). Duchne Kraus ( 2013 ) suggest tidal interaction with host stars may shape the brown dwarf desert. While assessing the characteristic time-scale for orbital decay, Damiani Daz ( 2016 ) find that F-type stars may host massive companions for a significantly longer time than G-type stars for orbital periods less than 5 d; however, they conclude that BD occurrence should largely be unaffected by tidal decay for orbital periods greater than 10 d, regardless of host mass. Debate continues on valid formation mechanisms of BDs and whether or not different formation mechanisms dominate in different mass, period and eccentricity regimes. Three main mechanisms are advocated in the field: (i) the ejection of protostellar embryos from their natal cloud cores (Boss 2001 ; Reipurth Clarke 2001 ), (ii) the fragmentation of protostellar discs (Stamatellos Whitworth 2009 ; Stamatellos etal. 2011 ) or (iii) collapsing molecular cloud cores (Hopkins 2012 ; Hennebelle Chabrier 2013 ), i.e. the same process as Sun-like stars. Through their statistical study, Ma Ge ( 2014 ) reported that BD companions with minimum masses below 42.5 M Jup have an eccentricity distribution consistent with that of massive planets, while those with masses above 42.5 M Jup have an eccentricity distribution consistent with that of binaries. Ma Ge ( 2014 ) also find that host stars of BD companions are not metal rich and have a significantly different metallicity distribution compared to host stars of giant planets, suggesting a formation mechanism different from the core-accretion (Ida Lin 2004 ) scenario. Ma Ge ( 2014 ) conclude that BD companions with minimum masses below 42.5 M Jup likely form in a protoplanetary disc through the disc gravitational instability scenario, and their eccentricity is excited through scattering, while BD companions with minimum masses above 42.5 M Jup likely form in the same way as stars, through molecular cloud fragmentation. Troup etal. ( 2016 ) find 14 candidate BD companions around metal-poor stars ([Fe/H]0.5), also challenging the core-accretion formation model for BDs, which they find unsurprising given that Carney etal. ( 2003 ) observed that lower metallicity populations generally have a higher number of binaries. Here, we present new BD candidate companions using data from the SDSS-III Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS; Ge etal. 2008 ). MARVELS observed 3300 stars with 10 RV measurements. Unlike APOGEE, MARVELS primarily targeted solar-like dwarfs, and thus, is complementary to the


O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O B-Dataset B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Dataset O O O O O O O O O O O O O O O O O O O O O O O B-Survey O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula O O O O O

(pessimistic). The most pessimistic lower limit for the background is ≈1 × 10 −16 (Dvorkin Barausse 2017 ; Bonetti et al. 2018 ), though most estimates suggest that A SB will be at least several times larger (Ravi et al. 2015 ). We also looked at two different values of the total time span observed after the end of NG11, T + = 10 or 20 years, for calculating ρ . In Table 1 , we show our results in terms of the amount of time per pulsar per year allocated given different values of A SB and T + . Table 1 Optimal Pulsar Cadences for a Stochastic Background Note. We assumed β = 13/3. Added time span T + is in units of years. Dashed entries formally have values, but are too small to be reported. 3.1. Maintaining the PTA: The Time Allocation per Pulsar Table 1 shows that our best pulsars do not overwhelmingly dominate the stochastic-background time allocation. This makes sense when we consider a hypothetical PTA where we ignore all T ij and χ ij and only have pulsars with white noise. Following Siemens et al. ( 2013 ) but including the differences in white noise and cadences, we have . Then, one can easily show that the total ρ maximizes when the “quality” of each pulsar, the white-noise spectrum , is similar, and thus one should spend more time on pulsars with higher white-noise rms. Lee et al. ( 2012 ) reached a similar result. Since the optimization performed is over complex nonlinear equations (Equations ( 1 ), ( 2 )), the results we obtain for an individual pulsar can differ compared with that of the scaling relations. For real PTAs, one should consider red noise, varying time baselines, changes in the relative contributions of white-noise parameters over time, and sky positions, which will modify the results accordingly, though the basic principle still applies. We see that the time allocation is of similar magnitude for all pulsars, i.e., no pulsar overwhelmingly dominates the time allocation, though several pulsars do not contribute significantly for certain assumed parameters and thus are not listed (when c i 1 hr/year). Comparing against the value of ρ determined from a continuation of the NG11 observing strategy versus the optimizations found here, we see a ∼5% increase in ρ for , but a nearly ∼8%–10% increase for . NANOGrav’s general strategy of observing many high-precision pulsars with roughly equal time (along with high-cadence programs) therefore currently provides close to optimal stochastic-background sensitivity. 3.2. Trimming the PTA: Removing Pulsars to Improve Sensitivity Figure 1 shows the effect of removing a pulsar from the array and whether reallocating its observing time will increase or decrease sensitivity to the stochastic background. We find that all 45 pulsars contribute significantly for decades-long experiments and that the relative importance of continuing to time these pulsars also tends to improve. However, note in Table 1 where certain pulsars become significant for T + = 20 years, whereas they are unlisted for


O O O O O B-Person I-Person O B-Person I-Person O O O O O B-Grant I-Grant I-Grant O B-Grant O O O B-Organization I-Organization I-Organization I-Organization O O O O O B-Observatory I-Observatory I-Observatory O B-Organization O B-Grant

We acknowledge helpful discussions with John ZuHone and Mateusz Ruszkowski. This work was supported by Chandra Awards GO1-12160X and GO2-13125X issued by the Chandra X-ray Observatory Center which is operated by the Smithsonian Astrophysical Observatory under NASA contract NAS8-03060.


O O B-Wavelength O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O B-Formula I-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Observatory B-Wavelength I-Wavelength O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

own reradiated IR photons ( for the most favorable geometry), so we assume that this boosting is unimportant. NGC 253 has a total infrared luminosity of erg s −1 , about half of which originates within a diameter of ∼200 pc from its center (Leroy et al. 2015b ), i.e., R src = 100 pc. The SW streamer has a “minimum mass” , a projected size on the sky of pc 2 , and a typical distance to the center of the order of pc. If we assume that the geometry corresponds to a cylinder 60 pc in diameter () illuminated by erg s −1 , the force due to radiation pressure applied at the base of the streamer would be dyn, resulting in an estimated acceleration of cm s −2 . In the absence of gravity, the resulting velocity at pc would be km s −1 , lower than the observed velocity before projection correction (Figure 4 ). If we instead assume that the radiation is exerting pressure on the long side of the cylinder (the geometry with the maximum area), f rad would be five times larger, with a corresponding km s −1 . Note, however, that the ratio of gravity to radiation pressure for stars is , where erg s −1 g for a fully sampled IMF containing young stars, and is the surface density of the cloud (Ψ is the light-to-mass ratio of the stellar population, e.g., Equation (33) in Kim et al. 2016 ). For the end-on geometry g cm −2 , while for the side-on geometry g cm −2 , resulting in . So, for our assumed geometry and mass, the net acceleration is between 6% and 81% of a rad , which would result in km s −1 . From the above estimates, it appears that radiation can contribute maybe up to a few tens of percent of the momentum, but it is extremely unlikely to completely explain the observations. Doing so would require using the most favorable geometric assumption (maximal cloud area, which maximizes f rad and minimizes ) and also assuming that there is almost no projection correction to the measured velocity (which requires a contrived geometry). This suggests that radiation pressure is not the dominant mechanism for accelerating the streamer, though it is non-negligible. Note also that any increase in the mass of the streamer over its minimum mass (see discussion in Section 3.6.1 ), or accounting for the old stars in the galaxy disk outside the starburst (which would increase gravity), would also reduce the importance of radiation pressure. Much higher resolution observations of the SW streamer may help further elucidate these questions, in particular, which mechanisms are driving the molecular gas in the outflow. 4. Summary Our new ALMA band 3 observations (CO and dense gas tracers) of the central starburst region of NGC 253 give new insights on the properties of the molecular outflowing gas originally discussed in Bolatto et al. ( 2013 ). The most prominent outflow feature toward the south, which is the main subject of this paper, possesses a large intrinsic velocity dispersion. Its extent and dispersion are consistent with an ejection from the disk starting about ∼1 Myr


O O O O O B-Organization O B-Grant O O B-Grant I-Grant I-Grant I-Grant O O O O B-Telescope O O B-Grant O O B-Organization I-Organization I-Organization I-Organization O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization O B-Grant O O O O B-Organization O O O O B-Grant O O O B-Organization I-Organization I-Organization I-Organization O O B-Grant B-Person O O O O B-Fellowship I-Fellowship O O B-Organization O O O B-Organization I-Organization I-Organization B-Person O O O O B-Location I-Location B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant O O B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant B-Person O B-Person O O O O O B-Organization I-Organization I-Organization O O B-Grant I-Grant B-Person O B-Person O O O B-Organization O O B-Organization O B-Organization B-Person O O O O B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization B-Grant I-Grant I-Grant I-Grant O B-Grant I-Grant I-Grant I-Grant O O B-Organization I-Organization I-Organization O O O O O O O O O O O O O O

This work is supported by NASA grant NNX16AC07G through the XMM-Newton Guest Observing Program, and through grants for HST program number 14054 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. The research at the Technion is supported by the I-CORE program of the Planning and Budgeting Committee (grant number 1937/12). N.A. is grateful for a visiting-professor fellowship at the Technion, granted by the Lady Davis Trust. E.B. received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 655324. S.B. and M.C. acknowledge financial support from the Italian Space Agency under grant ASI-INAF I/037/12/0. P.O.P. and F.U. acknowledge support from CNES and from PNHE of CNRS/INSU. G.P. acknowledges support by the Bundesministerium für Wirtschaft und Technologie/Deutsches Zentrum für Luft- und Raumfahrt (BMWI/DLR, FKZ 50 OR 1408 and FKZ 50 OR 1604) and the Max Planck Society. We thank the referee for useful comments that have been implemented in the manuscript.


O B-Telescope I-Telescope I-Telescope I-Telescope O O O O B-Organization I-Organization I-Organization I-Organization O O O O O B-Organization I-Organization O O O O O O O O B-Organization B-Person O B-Person O O O O B-Organization B-Location O B-Grant O O B-Organization B-Person O O O O B-Grant O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O O O O O B-Fellowship I-Fellowship I-Fellowship I-Fellowship

The Australia Telescope Compact Array is part of the Australia Telescope National Facility, which is funded by the Australian Government for operation as a National Facility managed by CSIRO. JFG and LFM are partially supported by MINECO (Spain) grant AYA2014-57369-C3-3 (co-funded by FEDER). LU acknowledges support from grant PE9-1160 of the Greek General Secretariat for Research and Technology in the framework of the program Support of Postdoctoral Researchers.


O B-Person B-Person O B-Person O O B-Location O B-Organization B-Grant O B-Grant O O O O O O O O O O O O O O B-Location B-Organization I-Organization I-Organization O B-Grant I-Grant B-Organization I-Organization I-Organization B-Person I-Person B-Person I-Person O O B-Grant I-Grant I-Grant I-Grant I-Grant I-Grant I-Grant I-Grant I-Grant O B-Person O B-Person B-Person O B-Organization O B-Grant O O B-Survey O O O O O B-Organization I-Organization I-Organization I-Organization O O O O B-Organization I-Organization I-Organization O O B-Location B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O B-Survey O O O B-URL O B-Survey O O O O B-Collaboration I-Collaboration I-Collaboration O O O O O O B-Collaboration I-Collaboration O O B-Organization I-Organization I-Organization O B-Collaboration I-Collaboration I-Collaboration B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization O B-Collaboration I-Collaboration I-Collaboration O B-Collaboration I-Collaboration I-Collaboration B-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization I-Organization O B-Collaboration I-Collaboration I-Collaboration I-Collaboration I-Collaboration B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization I-Organization B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization B-Organization I-Organization O B-Collaboration I-Collaboration I-Collaboration B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization B-Organization I-Organization B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization O B-Organization I-Organization O B-Survey I-Survey B-Survey O O O O O O O O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O B-Organization I-Organization O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization B-Location O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Location B-Organization I-Organization I-Organization I-Organization B-Organization I-Organization O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization O B-Observatory I-Observatory I-Observatory I-Observatory I-Observatory I-Observatory I-Observatory O B-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization I-Organization O O B-Organization I-Organization I-Organization I-Organization I-Organization O O O B-Grant O O O B-Organization I-Organization I-Organization O O B-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O O B-Grant O B-Organization I-Organization I-Organization B-Organization I-Organization I-Organization B-Organization O O B-Organization I-Organization I-Organization I-Organization

ACKNOWLEDGEMENTS HDP, HJR-P, and FA-F thank the Brazilian Agency CAPES (DS and PDSE programs) for the financial support of this research. Funding was also provided by the US National Science Foundation grant AST 16-15688, The Marvin Clan, Babette Josephs, Manit Limlamai, and the 2015 Crowd Funding Campaign to Support Milky Way Research, to CM and HJN. ARGJ thanks FAPESP proc. 2018/11239-8. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III web site is http://www.sdss3.org/ . SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. The Pan-STARRS1 Surveys (PS1) have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen’s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, and the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), and the Los Alamos National Laboratory.


O O O O O O O O O O O O O O O O O O O O O O B-Instrument O B-Formula I-Formula I-Formula B-Observatory O B-Formula I-Formula I-Formula O B-Telescope O B-Formula I-Formula I-Formula O O O O O O O B-Observatory O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula I-Formula B-Citation I-Citation I-Citation I-Citation O O O O O O B-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O B-Observatory O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O B-Telescope O O B-Wavelength I-Wavelength O O O O O O B-Observatory B-Wavelength I-Wavelength O B-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O B-Telescope O O O O B-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength I-Wavelength O O O O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O B-Observatory O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O B-Observatory O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O

profiles (azimuthally averaged) for the dust continuum and line images. Shown are profiles derived from images convolved with representative beam sizes for SPHERE (blue, FWHM = 0.031′′), ALMA (black, FWHM = 0.012′′), and ngVLA (red, FWHM = 0.004′′). The continuum non-detections of wide-orbit CPDs with ALMA indicate low dust masses or very compact optically thick disks ( r out ≲ 0.5 au, Wu et al. 2017a ). Compared to those non-detections, the 860 μ m disk in our reference model seems to be too large. We discuss this further in Sects 3.2 and 3.3 . In contrast to the dust emission the 12 CO J = 3 − 2 emission traces mostly the outer disk and can, in principle, be spatially resolved with ALMA even with larger beams. In the reference model the line is optically thick throughout the disk (see Fig. 4 ) and traces only the upper layers of the disk. Because of the high optical depths 12 CO J = 3 − 2 is very sensitive to the disk size (i.e. emitting area) and the temperature. The different apparent extents of the dust and line emission in our model is similar to observations of T Tauri disks (e.g. de Gregorio-Monsalvo et al. 2013 ; Ansdell et al. 2018 ). It is still unclear if this difference is only caused by optical depth effects or if radial dust migration also plays a role ( Woitke et al. 2016 ; Facchini et al. 2017 ). In our models the cause is solely the different dust and line optical depths. For ngVLA observations at 3 mm the situation is similar to the ALMA Band 7 at 860 μ m. The main difference is the possible higher spatial resolution of the ngVLA (0.004′′, 0.6 au at d = 150 au), which might allow us to also resolve the dust disk (see right panel of Fig. 3 ). Compared to the 860 μ m emission, the emission at 3 mm is weaker and the optically thick region of the dust and the gas are slightly smaller (see Fig. 4 ). 3.2 Exploring disk mass and size In Fig. 5 we compare the modelled fluxes for the dust continuum and gas lines to the 5 σ detection limits of ngVLA and ALMA (6 h on-source observing time, see Appendix C ). We report the peak(maximum) fluxes determined from the synthetic beam convolved continuum images and line cubes (see Appendix D ). If the peak flux of the model is above the reported sensitivity limit a 5 σ detection is possible in the case of the lines in at least one channel. Figure 5 shows the reference model and models with varying R tap (i.e. changing the radial extent of the disk) and with a factor of 10 lower disk mass. Indicated in Fig. 5 are also the 3 σ rms values reported by Wu et al. (2017a , Table 1 ) for their observations of five potential CPDs with ALMA in Band 6. The average on-source integration time for their sample is around 12 min. Fig. 4 Vertical optical depth τ for the dust and for 12 CO lines as a function of radius in the reference model (see also Fig. 3 ). The horizontal dark grey line indicates τ = 1. As Fig. 5 shows our reference model is easily detectable in the dust, also with significantly shorter


O O O O O O B-Person I-Person O O O O O O O O O B-Person I-Person B-Person I-Person B-Person I-Person O B-Person I-Person O O O O O O O O O O O O O O O O O O B-Observatory I-Observatory I-Observatory O O O O O O O O O B-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O O B-Organization I-Organization I-Organization I-Organization I-Organization O O O O O O O O O O O O B-Organization I-Organization I-Organization O O O O O O O O O O O O O O O O O O B-Location I-Location O O O O O O B-Location O O O O O O O O O O O O O O O O O O O O O O O O O B-Observatory I-Observatory O O O B-Archive I-Archive I-Archive O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O O O O O B-Organization O O O O B-Collaboration I-Collaboration O B-Organization I-Organization I-Organization B-Location I-Location O B-Organization I-Organization I-Organization B-Location B-Organization B-Location B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Location O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Location

The authors would like to thank Michele Fumagalli for sharing his composite spectrum of the LLSs, and Feige Wang, Jonathan Stern, Bram Venemans, and Roberto Decarli for very helpful discussions and feedback. Some of the data presented in this paper were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This paper contains data based on observations obtained at the Gemini Observatory, acquired through the Gemini Observatory Archive, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).


O O O B-Telescope O B-Telescope O O O O B-Person I-Person I-Person O B-Organization O B-Person I-Person O O O O O O O O O O O O O O O B-Person I-Person O B-Person I-Person O O O B-Person O O O O O O B-Person I-Person I-Person O B-Person I-Person B-Person O O B-Organization I-Organization I-Organization I-Organization O B-Organization O B-Grant O O O O O O O O B-Person O O O O B-Organization I-Organization I-Organization O O O O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization O B-Grant I-Grant I-Grant I-Grant O O O B-Organization I-Organization I-Organization I-Organization O O O O O B-Observatory I-Observatory I-Observatory O O O O O B-Organization O O B-Grant B-Person O B-Person O O O O B-Telescope O B-Grant I-Grant O O O B-Person O O O O B-Organization O B-Grant O B-Organization I-Organization O O B-Organization I-Organization I-Organization I-Organization B-Person O B-Person O O O O O B-Person O B-Person I-Person O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope I-Telescope I-Telescope B-Telescope I-Telescope I-Telescope I-Telescope O O O O B-Archive I-Archive I-Archive I-Archive I-Archive I-Archive I-Archive I-Archive O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O B-Organization O B-Grant I-Grant O B-Telescope O O B-Organization O O O O O O O O O B-Organization O O O B-Organization O O O O O O O O O O B-Observatory I-Observatory I-Observatory I-Observatory O O O O O O O O O B-Organization I-Organization I-Organization I-Organization O B-Organization I-Organization I-Organization O B-Organization O O O O O O O O O O O O B-Organization I-Organization I-Organization I-Organization O O O O O O B-Observatory I-Observatory O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O O O O O B-Organization O O O O B-Collaboration I-Collaboration O B-Organization I-Organization I-Organization B-Location I-Location O B-Organization I-Organization I-Organization B-Location B-Organization B-Location O B-Organization I-Organization I-Organization B-Location B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Location O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Location O O O O O O B-Observatory O O O B-Observatory I-Observatory O B-Observatory I-Observatory O O O O O O O O O B-Archive I-Archive I-Archive O B-Observatory B-Telescope B-Telescope B-Instrument B-Telescope B-Instrument B-Telescope B-Instrument B-Instrument B-Instrument B-Telescope B-Instrument B-Telescope B-Instrument B-Telescope B-Instrument B-Instrument B-Telescope

We thank the XMM-Newton and HST teams, in particular Project Scientist N. Schartel and STScI director M. Mountain, for the approval and prompt scheduling of our DD requests. We are also grateful to James Guillochon and Ryan Chornock for valuable discussions. D.R.P. is grateful for valuable discussions with Sjoert van Velzen and Nick Stone. S.B.C. thanks the Aspen Center for Physics and NSF Grant #1066293 for hospitality during the preparation of this manuscript. K.L.P. acknowledges support from the UK Space Agency. Support for this work was provided by the National Aeronautics and Space Administration (NASA) through Chandra Award Number GO3–14107X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. D.R.P. and S.B.C. also acknowledge support from HST grant GO-13611-006 A. The work of A.V.F. was made possible by NSF grant AST-1211916, the TABASGO Foundation, and the Christopher R. Redlich Fund. A.V.F. and S.B.C. also acknowledge the support of Gary and Cynthia Bengier. Finally, we would like to thank the referee for his/her careful comments and suggestions. The scientific results reported in this article are based in part on observations made by the Chandra X-ray Observatory, NASA/ESA Hubble Space Telescope , obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555, and XMM-Newton , an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA; the observatory was made possible by the generous financial support of the W. M. Keck Foundation. Also, observations were obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina). Also, based on observations made with ESO Telescopes at the La Silla or Paranal Observatories. We acknowledge the use of public data from the Swift data archive. Facilities: Swift (XRT), XMM (EPIC), Chandra (ACIS), VLT (FORS2, HAWK-I, XSHOOTER), Keck (LRIS), Gemini:South (GMOS-S), HST (WFC3, ACS), VLBA


O O O O O O B-Organization I-Organization O O B-Grant I-Grant B-Grant I-Grant O B-Grant I-Grant B-Person O B-Person O O O O B-Grant I-Grant I-Grant O O B-Organization I-Organization I-Organization I-Organization B-Organization B-Person I-Person I-Person I-Person O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization O O O B-Grant I-Grant I-Grant B-Grant I-Grant B-Person O O O O O O B-Grant I-Grant I-Grant O O B-Organization I-Organization I-Organization I-Organization B-Grant O B-Telescope

This work was supported by the Chinese NSF through grants NSF 11673066, NSF 11673051, and NSF 11873019. B.Z. and Y.W.W. are supported by the 100 Talents Project of the Chinese Academy of Sciences (CAS). K. L. J. Rygl acknowledges financial support by the Italian Ministero dell’Istruzione Università e Ricerca through the grant Progetti Premiali 2012-iALMA (CUP C52I13000140001). Y.W.W. is supported in part by the West Light Foundation of the Chinese Academy of Sciences (XAB2016A06). Facility: VLBA.


O O O O O O O O O O O O O O B-Telescope O B-Telescope B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O B-ObservationalTechniques O O O O O O O O O O O O O B-Wavelength O B-Wavelength B-Model O O O O B-Model O O B-Software O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O B-Wavelength O O O O O B-Software O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model O O B-Formula I-Formula I-Formula I-Formula B-Formula I-Formula I-Formula I-Formula O B-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula I-Formula B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O B-Formula I-Formula I-Formula O O O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O B-Telescope B-Citation I-Citation I-Citation I-Citation O O B-Telescope B-Citation I-Citation I-Citation I-Citation O O O O O O O O B-Wavelength B-ObservationalTechniques I-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O O O B-ObservationalTechniques I-ObservationalTechniques O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Survey O O O O O O O O O O O O B-Instrument I-Instrument I-Instrument I-Instrument B-Instrument O O B-Instrument I-Instrument O O B-Telescope O O B-Grant B-Grant O B-Grant B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O B-Wavelength B-Wavelength I-Wavelength I-Wavelength O B-Wavelength I-Wavelength I-Wavelength B-ObservationalTechniques I-ObservationalTechniques O O O B-CelestialRegion I-CelestialRegion O B-CelestialRegion B-CelestialRegion B-CelestialRegion B-CelestialRegion O B-CelestialRegion B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula O O O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength B-Wavelength I-Wavelength O O O O O B-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O

that will be found by next-generation space-based grism surveys, such as those planned for Euclid and WFIRST (Maciaszek et al. 2014 ; Gong et al. 2016 ). Section 2 briefly describes our galaxy sample and the archival photometry and spectrophotometry available for analysis. Section 3 lists the parameters used for modeling the galaxies’ UV through near-IR SEDs and introduces our new SED fitting code, MCSED . Section 4 explores the basic properties of the Bowman et al. ( 2019 ) sample, the systematics of the data set, and the effect that various assumptions have on the results. Section 5 extends our analysis to the mid- and far-IR and tests the ability of MCSED to explore the balance between the sight-line attenuation of the UV stellar continua by dust and its isotropic reradiation at longer wavelengths. Finally, in Section 6 , our results are placed in the context of other work at these redshifts and within the framework of simulations. Throughout this paper, we assume a ΛCDM cosmology, with Ω Λ = 0.7, Ω M = 0.3, and H 0 = 70 km s −1 Mpc −1 (Bennett et al. 2013 ). 2. The Sample At present, the largest samples of z ≳ 2 galaxies have been constructed from broadband photometry and color selection via the use of photometric redshifts (e.g., Reddy et al. 2012 ; Bouwens et al. 2015 ; Ono et al. 2018 ). However, in the near future, space missions such as Euclid/NISP (Maciaszek et al. 2014 ) and WFIRST (Gong et al. 2016 ) will detect millions of emission-line galaxies via near-IR slitless grism spectroscopy. Since the selection criteria for these galaxies will differ substantially from those identified using broadband photometric techniques, we can expect the distribution of the galaxies’ physical properties to differ as well. To prepare for this era, we can study the objects found by the pathfinding 3D-HST survey, a 625 arcmin 2 set of two-orbit observations taken with the Wide Field Camera 3 (WFC3) and the G141 grism on the HST (GO programs 11600, 12177, and 12328; Momcheva et al. 2016 ; Weiner AGHAST Team 2014 ). This data set consists of R ∼ 130 near-IR (1.08 μ m λ 1.68 μ m) slitless spectroscopy within the deep CANDELS fields of AEGIS, COSMOS, UDS, GOODS-N, and GOODS-S (Giavalisco et al. 2004 ; Davis et al. 2007 ; Lawrence et al. 2007 ; Scoville et al. 2007 ). Tens of thousands of objects are detectable on these frames, but of special interest are galaxies in the redshift range 1.90 z 2.35. In this window, the emission lines of [O ii ] λ 3727, [Ne iii ] λ 3869, H β , and the distinctively shaped [O iii ] blended doublet λλ 4959, 5007 are simultaneously present in the bandpass. This set of observable emission lines, which includes two different ionization states of oxygen, not only enables the determination of unambiguous redshifts but also allows for the direct detection of galaxies over an extremely wide range of metallicities and ionization parameters. Bowman et al. ( 2019 ) recently created a sample of 1952 such oELGs by vetting the list of 1.90


O O O O O O O O O O O O O O B-Citation I-Citation I-Citation O O O O O O O O O O O B-CelestialObject B-CelestialObject O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O B-CelestialObject I-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O O O O O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O B-CelestialObjectRegion I-CelestialObjectRegion O O O O B-CelestialObject B-CelestialObject B-CelestialObject O O B-CelestialObject I-CelestialObject B-CelestialObject O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Formula I-Formula I-Formula I-Formula O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O

flows merely graze past each other appear qualitatively similar to the fits provided by Lombardi et al. to the N-PDFs deduced by them for clouds such as the Perseus, Pipe or the California. All of these latter clouds exhibit little star-forming activity. The potential star-forming ability of a cloud can also be quantitatively assessed by investigating into the fraction of gas cycled into the dense phase. The latter realization, realization 4, is most inefficient in transforming gas into the dense phase as is reflected by the relatively small dense-gas fraction in the plot on the upper panel of Fig. 6 . Similarly, the SFF shown on the lower panel of Fig. 6 , for this latter case declines rapidly to less than a percent while that for the remaining three realizations, can be seen to rise steadily. In fact, Orkisz et al. ( 2017 ) attribute the observed poor efficiency of star formation in the Orion B cloud to the impact of large-scale differential motion causing the gas within the cloud to shear. The next set of plots in Fig. 7 showing the cumulative distribution of gas mass as a function of visual extinction (actually calculation for the K -band extinction), is also quite revealing from the perspective of the star-forming ability of a cloud. Similar plots were deduced by Lada, Lombardi Alvés ( 2010 ) for an ensemble of MCs in the Solar neighbourhood. Clouds such as the Pipe, Perseus, California and the Lupus 1, 3 and 4 known for their poverty in forming stars, showed mass distribution very similar to that for clouds assembled via collisions having a large impact parameter (realization 4 here), where there is very little mass at large extinction. By contrast, the mass distribution for the cloud assembled in realization 1, where the collision was almost head-on is similar to that for MCs such as the Orion or Ophiuchus that form stars more efficiently. It is of course true that stellar feedback in these latter clouds must also contribute to star formation in these latter clouds. We therefore restrict ourselves to the inference that a pristine cloud assembled via head-on or near head-on collision is likely to cycle a larger fraction of gas to higher extinctions ( A K > 1), which could then possibly become future birth-sites for stars. It is indeed interesting that a relatively simple self-gravitating, hydrodynamic model such as the one discussed here can possibly reconcile the observed variations in the distribution of gas mass as a function of visual extinction in nearby MCs. Finally, we examined the possible correlation between the fraction of gas cycled into the dense phase and the relative strength of compressional/solenoidal modes in the velocity field induced in the assembled cloud. The propensity of compressional modes towards assembling putative star-forming gas was demonstrated by Federrath, Klessen Schmidt ( 2008 ). They showed numerically that gas dominated by compressional turbulence, as indicated by the strength of the so-called driving