bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparing the pre-SNe feedback and environmental pressures for 6000 H iiregions across 19 nearby spiral galaxies
Authors: Barnes A T , Glover S C O , Kreckel K , Ostriker E C , Bigiel F , Belfiore F , Bešlić I , Blanc G A , Chevance M , Dale D A , Egorov O , Eibensteiner C , Emsellem E , Grasha K , Groves B A , Klessen R S , Kruijssen J M D , Leroy A K , Longmore S N , Lopez L , McElroy R , Meidt S E , Murphy E J , Rosolowsky E , Saito T , Santoro F , Schinnerer E , Schruba A , Sun J , Watkins E J , Williams T G 
Published: October 2021

ABSTRACTThe feedback from young stars (i.e. pre-supernova) is thought to play a crucial role in molecular cloud destruction. In this paper, we assess the feedback mechanisms acting within a sample of 5810 H ii regions identified from the PHANGS-MUSE survey of 19 nearby (&lt;20 Mpc) star-forming, main-sequence spiral galaxies [log(M⋆/M⊙) = 9.4–11]. These optical spectroscopic maps are essential to constrain the physical properties of the H ii regions, which we use to investigate their internal pressure terms. We estimate the photoionized gas (Ptherm), direct radiation (Prad), and mechanical wind pressure (Pwind), which we compare to the confining pressure of their host environment (Pde). The H ii regions remain unresolved within our ∼50–100 pc resolution observations, so we place upper (Pmax) and lower (Pmin) limits on each of the pressures by using a minimum (i.e. clumpy structure) and maximum (i.e. smooth structure) size, respectively. We find that the Pmax measurements are broadly similar, and for Pmin the Ptherm is mildly dominant. We find that the majority of H ii regions are overpressured, Ptot/Pde = (Ptherm + Pwind + Prad)/Pde &gt; 1, and expanding, yet there is a small sample of compact H ii regions with Ptot,max/Pde &lt; 1 (∼1 per cent of the sample). These mostly reside in galaxy centres (Rgal &lt; 1 kpc), or, specifically, environments of high gas surface density; log(Σgas/M⊙ pc−2) ∼ 2.5 (measured on kpc-scales). Lastly, we compare to a sample of literature measurements for Ptherm and Prad to investigate how dominant pressure term transitions over around 5 dex in spatial dynamic range and 10 dex in pressure.
Spiral density-wave structure parameters in the solar neighbourhood derived from longitudinal velocities of Gaia EDR3 OB stars: 3D approach
Authors: Griv Evgeny , Gedalin Michael , Mróz Przemek , Liu De-Jian , Jiang Ing-Guey 
Published: October 2021

ABSTRACT
Distances and transverse along the Galactic longitude velocities vl of 2640 Gaia EDR3 O–B2 stars of Xu et al. within 2.5 kpc from the Sun and 250 pc from the Galactic plane with relative distance and velocity accuracies of &lt;10 and &lt;50 per cent are selected. Under the assumption of spiral density waves, both Galactic differential rotation parameters and parameters of the wave structure in this solar neighbourhood are derived from observed vl. In contrast to all preceding studies, we take into account the effect of small but finite thickness of the disc of the Galaxy on even parity (‘sausage’) gravity perturbations of the kind investigated by Lin and Shu. As previously predicted by the modified theory of 3D density waves, two scales of periodic rarefaction–compression irregularity of the vl velocity field with the radial λ0 ≈ 1.5 kpc and vertical ξ0 ≈ 1.0 kpc wavelengths in the form of a spiral wave propagating in the disc are revealed. The Gaia’s DR2 line-of-sight and EDR3 longitudinal velocities analyses performed in the last papers of a series exhibit consistent findings, thus providing a further evidence to support the Lin–Shu density-wave proposal.
compaso: A new halo finder for competitive assignment to spherical overdensities
Authors: Hadzhiyska Boryana , Eisenstein Daniel , Bose Sownak , Garrison Lehman H , Maksimova Nina 
Published: October 2021

ABSTRACT
We describe a new method (compaso) for identifying groups of particles in cosmological N-body simulations. compaso builds upon existing spherical overdensity (SO) algorithms by taking into consideration the tidal radius around a smaller halo before competitively assigning halo membership to the particles. In this way, the compaso finder allows for more effective deblending of haloes in close proximity as well as the formation of new haloes on the outskirts of larger ones. This halo-finding algorithm is used in the abacussummit suite of N-body simulations, designed to meet the cosmological simulation requirements of the Dark Energy Spectroscopic Instrument (DESI) survey. compaso is developed as a highly efficient on-the-fly group finder, which is crucial for enabling good load-balancing between the GPU and CPU and the creation of high-resolution merger trees. In this paper, we describe the halo-finding procedure and its particular implementation in abacus, accompanying it with a qualitative analysis of the finder. We test the robustness of the compaso catalogues before and after applying the cleaning method described in an accompanying paper and demonstrate its effectiveness by comparing it with other validation techniques. We then visualize the haloes and their density profiles, finding that they are well fit by the NFW formalism. Finally, we compare other properties such as radius–mass relationships and two-point correlation functions with that of another widely used halo finder, rockstar.
Are interactions with neutron star merger winds shaping the jets?
Authors: Nativi L , Lamb G P , Rosswog S , Lundman C , Kowal G 
Published: October 2021

ABSTRACT
Jets can become collimated as they propagate through dense environments and understanding such interactions is crucial for linking physical models of the environments to observations. In this work, we use 3D special-relativistic simulations to study how jets propagate through the environment created around a neutron star merger remnant by neutrino-driven winds. We simulate four jets with two different initial structures, top-hat and Gaussian, and two luminosities. After jet breakout, we study the angular jet structures and the resulting afterglow light curves. We find that the initial angular structures are efficiently washed out during the propagation, despite the small wind mass of only ∼10−3 M⊙. The final structure depends on the jet luminosity as less energetic jets are more strongly collimated, and entrainment of baryons leads to a moderate outflow Lorentz factor (≈40). Although our jets are not specifically intended to model the outflows of the GW170817 event, we show that they can be used to produce light curves consistent with the afterglow observed in the aftermath of GW170817. Using this procedure, we show how the inferred physical parameters e.g. inclination angle, ambient particle number density, can vary substantially between independent fits of the same dataset, and appear to be sensitive to smaller details of the angular jet shape, indicating that observationally inferred parameters may depend sensitively on the employed jet models.
A comparison of 2D Magnetohydrodynamic supernova simulations with the CoCoNuT-FMT and Aenus-Alcar codes
Authors: Varma Vishnu , Müller Bernhard , Obergaulinger Martin 
Published: October 2021

ABSTRACT
Code comparisons are a valuable tool for the verification of supernova simulation codes and the quantification of model uncertainties. Here, we present a first comparison of axisymmetric magnetohydrodynamic (MHD) supernova simulations with the CoCoNuT-FMT and Aenus-Alcar codes, which use distinct methods for treating the MHD induction equation and the neutrino transport. We run two sets of simulations of a rapidly rotating 35M⊙ gamma-ray burst progenitor model with different choices for the initial field strength, namely $10^{12}\, \mathrm{G}$ for the maximum poloidal and toroidal field in the strong-field case and $10^{10}\, \mathrm{G}$ in the weak-field case. We also investigate the influence of the Riemann solver and the resolution in CoCoNuT-FMT. The dynamics is qualitatively similar for both codes and robust with respect to these numerical details, with a rapid magnetorotational explosion in the strong-field case and a delayed neutrino-driven explosion in the weak-field case. Despite relatively similar shock trajectories, we find sizeable differences in many other global metrics of the dynamics, like the explosion energy and the magnetic energy of the proto-neutron star. Further differences emerge upon closer inspection, for example, the disc-like surface structure of the proto-neutron star proves high sensitivity to numerical details. The electron fraction distribution in the ejecta as a crucial determinant for the nucleosynthesis is qualitatively robust, but the extent of neutron- or proton-rich tails is sensitive to numerical details. Due to the complexity of the dynamics, the ultimate cause of model differences can rarely be uniquely identified, but our comparison helps gauge uncertainties inherent in current MHD supernova simulations.
Orbit evolution in growing stellar bars: bar-supporting orbits at the vertical ILR region
Authors: Manos T , Skokos Ch , Patsis P A 
Published: October 2021

ABSTRACT
We investigate the evolution of orbital shapes at the inner Lindblad resonance region of a rotating 3D bar, the mass of which is growing with time. We evaluate in time-dependent models, during a 5 Gyr period, the importance of orbits with initial conditions known to play a significant role in supporting peanut-like structures in autonomous systems. These orbits are the central family of periodic orbits (x1) and vertical perturbations of it, orbits of its standard 3D bifurcations at the region (x1v1 and x1v2), as well as orbits in their neighbourhood. The knowledge of the regular or chaotic character of these orbits is essential as well, because it allows us to estimate their contribution to the support of a rotating bar and, more importantly, the dynamical mechanisms that make it possible. This is calculated by means of the GALI2 index. We find that orbital patterns existing in the autonomous case, persist for longer times in the more massive bar models, and even more so in a model in which the central spheroid component of our adopted galactic potential becomes rather insignificant. The peanut-supporting orbits that we find, have a regular or, in most cases, a weakly chaotic character. There are cases in which orbits starting close to unstable periodic orbits in an autonomous model behave as regular and support the bar when its mass increases with time. As a rule of thumb for the orbital dynamics of our non-autonomous models at a certain time, can be considered the dynamics of the corresponding frozen systems around that time.
Synthetic photometry of OB star clusters with stochastically sampled IMFs: analysis of models and HST observations
Authors: Orozco-Duarte Rogelio , Wofford Aida , Vidal-García Alba , Bruzual Gustavo , Charlot Stephane , Krumholz Mark R , Hannon Stephen , Lee Janice , Wofford Timothy , Fumagalli Michele , Dale Daniel , Messa Matteo , Grebel Eva K , Smith Linda , Grasha Kathryn , Cook David 
Published: October 2021

ABSTRACT
We present a pilot library of synthetic NUV, U, B, V, and I photometry of star clusters with stochastically sampled IMFs and ionized gas for initial masses, Mi = 103, 104, and 105 M⊙; t = 1, 3, 4, and 8 Myr; Z = 0.014 and Z = 0.002; and log(US) = −2 and −3. We compare the library with predictions from deterministic models and observations of isolated low-mass (&lt;104 M⊙) star clusters with co-spatial compact H ii regions. The clusters are located in NGC 7793, one of the nearest galaxies observed as part of the HST LEGUS and Hα-LEGUS surveys. (1) For model magnitudes that only account for the stars: (a) the residual |deterministic mag - median stochastic mag| can be ≥0.5 mag, even for Mi = 105 M⊙; and (b) the largest spread in stochastic magnitudes occurs when Wolf–Rayet stars are present. (2) For Mi = 105 M⊙: (a) the median stochastic mag with gas can be &gt;1.0 mag more luminous than the median stochastic magnitude without gas; and (b) nebular emission lines can contribute with $\gt 50{{\ \rm per\ cent}}$ and $\gt 30{{\ \rm per\ cent}}$ to the total emission in the V and I bands, respectively. (3) Age-dating OB-star clusters via deterministic tracks in the U-B versus V-I plane is highly uncertain at Z = 0.014 for Mi ∼ 103 M⊙ and Z = 0.002 for Mi ∼ 103–105 M⊙. (4) For low-mass clusters, the V-band extinction derived with stochastic models significantly depends on the value of log(US). (5) The youngest clusters tend to have higher extinction. (6) The majority of clusters have multi-peaked age PDFs. (7) Finally, we discuss the importance of characterizing the true variance in the number of stars per mass bin in nature.
GRB variabilities and following gravitational waves induced by gravitational instability in NDAFs
Authors: Shahamat Narjes , Abbassi Shaharam , Liu Tong 
Published: October 2021

ABSTRACT
The present work proposes a new formalism for the inner regions of a neutrino-dominated accretion flows (NDAFs) by considering the self-gravity, where the neutrino opacity is high enough to make neutrinos trapped becoming a dominant factor in the transportation of energy and angular momentum over the magneto rotational instability. We investigate the possibility of gravitational instability and fragmentation to model the highly variable structure of the prompt emission in gamma-ray bursts (GRBs). The results lead us to introduce the gravitational instability, in these inner regions, as a source of a new viscosity that is of the same functional form as that of the β-prescription of viscosity. Such a consideration brings about fragmentation in the unstable inner disc. In addition, we find the consequent clumpy structure of this area capable to account for the temporal variability of GRB’s light curve, especially for the lower choices of the parameter β, ∼10−5. Finally, we predict the formation of gravitational waves through the migration of fragments before being tidally disrupted. These waves appear to be detectable via a range of current and future detectors from LIGO to Cosmic Explorer.
Direct measurements of infrared intensities of HCN and H2O + HCN ices for laboratory and observational astrochemistry
Authors: Gerakines Perry A , Yarnall Yuki Y , Hudson Reggie L 
Published: October 2021

ABSTRACT
Hydrogen cyanide (HCN) is found in a wide variety of extraterrestrial environments within and beyond the Solar system, and for that reason laboratory spectroscopists have studied this compound in many spectral regions, including the infrared (IR). However, one aspect that remains to be investigated is the intrinsic IR spectral intensities of solid HCN as opposed to relative band strengths, intrinsic intensities being needed to measure HCN abundances. Here we report measurements of IR absorption coefficients and band strengths, along with supporting refractive indices and densities, of both amorphous and crystalline HCN at two temperatures, one for interstellar work and one more relevant to the outer Solar system. Spectra are presented at both temperatures, along with optical constants that can be used in numerical models. Despite widespread and longstanding interest in and investigations of solid HCN, this is the first time that the properties we are reporting have been measured in a single laboratory, avoiding the need for estimates or to combine results from various authors. We find that our measured band strength of ∼1 × 10–17 cm molecule–1 for the C≡N vibration of HCN, in both amorphous HCN and in an H2O-rich ice, is substantially higher than an earlier estimate. Unless errors of 100 per cent can be tolerated, then our new value requires a rescaling of earlier work. Our results shed light on why HCN and other nitriles have been so difficult to identify in the solid state, in contrast to their many detections in the gas phase.
Models of metal-poor stars with different initial abundances of C, N, O, Mg, and Si – I. Bolometric corrections derived from new MARCS synthetic spectra and their implications for observed colour–magnitude diagrams
Authors: VandenBerg Don A , Edvardsson Bengt , Casagrande Luca , Ferguson Jason W 
Published: October 2021

ABSTRACTNew, high-resolution MARCS synthetic spectra have been calculated for more than a dozen mixtures of the metals allowing, in turn, for variations in C:N:O, [CNO/Fe], and enhanced abundances of C, O, Mg, and Si. Bolometric corrections (BCs) for many of the broad-band filters currently in use have been generated from these spectra. Due to improved treatments of molecules that involve atoms of C, N, and O, the BCs for UV and blue passbands, in particular, differ substantially from those derived from previous MARCS models. These differences, and the effects on the BCs of varying the abundances of the metals, are shown in a number of instructive plots. Stellar evolutionary grids for −2.5 ≤ [Fe/H] ≤−0.5 have also been computed for the different mixtures. Isochrones based on these tracks are intercompared on the theoretical H–R diagram and on a few of the colour–magnitude diagrams that can be constructed from HST Wide Field Camera 3 (WFC3) F336W, F438W, F606W, F814W, F110W, and F160W observations. For the first application of these models, isochrones have been fitted to WFC3 photometry of the globular cluster NGC 6496 from the HST UV Legacy Survey, with very encouraging results.
Deep Chandra observations of diffuse hot plasma in M83
Authors: Wang Q Daniel , Zeng Yuxuan , Bogdán Ákos , Ji Li 
Published: October 2021

ABSTRACT
It is widely believed that galaxy formation and evolution is regulated by stellar mechanical feedback in forms of fast stellar winds and supernova explosions. However, the coupling of this feedback with the interstellar medium remains poorly understood. We examine how the coupling may be traced by diffuse soft X-ray emission in M83 – a nearby face-on spiral galaxy undergoing active star formation, based chiefly on 729 ks Chandra observations. Our main findings are (1) the X-ray emission is enhanced not only along the galaxy’s grand spiral arms, but also clearly in their downstreams; (2) the spectrum of the emission can be well characterized by a supersolar metallicity plasma with a lognormal temperature distribution, plus an X-ray absorption of a lognormal column density distribution; and (3) the intensity of the emission is strongly anticorrelated with the dust obscuration seen in optical images of the galaxy. These findings suggest (A) the morphology of the X-ray emission is likely due to the convolution of the feedback heating of the plasma with its thermal and dynamical evolution; (B) the X-ray emission, accounting for $\sim 10{{\ \rm per\ cent}}$ of the feedback energy input rate, probably traces only the high-energy tail of the radiation from the plasma; (C) a good fraction of the recent star-forming regions seems sufficiently energetic to produce multi-phased outflows, likely responsible for much of the dust obscuration and X-ray absorption. Direct confrontation of the findings with theories/simulations could help to understand the underlying astrophysics of the coupling and how the hot plasma shapes the interstellar medium.
Population III star formation in an X-ray background – I. Critical halo mass of formation and total mass in stars
Authors: Park Jongwon , Ricotti Massimo , Sugimura Kazuyuki 
Published: October 2021

ABSTRACT
The first luminous objects forming in the universe produce radiation backgrounds in the far-ultraviolet and X-ray bands that affect the formation of Population III stars. Using a grid of cosmological hydrodynamics zoom-in simulations, we explore the impact of the Lyman–Warner (LW) and X-ray radiation backgrounds on the critical dark matter (DM) halo mass for Population III star formation and the total mass in stars per halo. We find that the LW radiation background lowers the H2 fraction and delays the formation of the Population III stars. On the other hand, X-ray irradiation anticipates the redshift of collapse and reduces the critical halo mass, unless the X-ray background is too strong and gas heating shuts down gas collapse into the haloes and prevents star formation. Therefore, an X-ray background can increase the number of DM haloes forming Population III stars by about a factor of 10, but the total mass in stars forming in each halo is reduced. This is because X-ray radiation increases the molecular fraction and lowers the minimum temperature of the collapsing gas (or equivalently the mass of the quasi-hydrostatic core) and therefore slows down the accretion of the gas on to the central protostar.
Population III star formation in an X-ray background – II. Protostellar discs, multiplicity, and mass function of the stars
Authors: Park Jongwon , Ricotti Massimo , Sugimura Kazuyuki 
Published: October 2021

ABSTRACT
Disc fragmentation plays an important role in determining the number of primordial stars (Pop III stars), their masses, and hence the initial mass function. In this second paper of a series, we explore the effect of uniform far-ultraviolet H2-photodissociating and X-ray radiation backgrounds on the formation of Pop III stars using a grid of high-resolution zoom-in simulations. We find that, in an X-ray background, protostellar discs have lower surface density and higher Toomre Q parameter, so they are more stable. For this reason, X-ray irradiated discs undergo fewer fragmentations and typically produce either binary systems or low-multiplicity systems. In contrast, the cases with weak or no X-ray irradiation produce systems with a typical multiplicity of 6 ± 3. In addition, the most massive protostar in each system is smaller by roughly a factor of 2 when the disc is irradiated by X-rays, due to lower accretion rate. With these two effects combined, the initial mass function of fragments becomes more top-heavy in a strong X-ray background and is well described by a power law with slope 1.53 and high-mass cutoff of 61 M⊙. Without X-rays, we find a slope 0.49 and cutoff mass of 229 M⊙. Finally, protostars migrate outward after their formation likely due to the accretion of high-angular momentum gas from outside and the migration is more frequent and significant in absence of X-ray irradiation.
A multimission catalogue of ultraluminous X-ray source candidates
Authors: Walton D J , Mackenzie A D A , Gully H , Patel N R , Roberts T P , Earnshaw H P , Mateos S 
Published: October 2021

ABSTRACT
We present a new, multimission catalogue of ultraluminous X-ray source (ULX) candidates, based on recent data releases from each of the XMM–Newton, Swift, and Chandra observatories (the 4XMM-DR10, 2SXPS, and CSC2 catalogues, respectively). This has been compiled by cross-correlating each of these X-ray archives with a large sample of galaxies primarily drawn from the HyperLEDA archive. Significant efforts have been made to clean the sample of known non-ULX contaminants (e.g. foreground stars, background active galactic nuclei, supernovae), and also to identify ULX candidates that are common to the different X-ray catalogues utilized, allowing us to produce a combined ‘master’ list of unique sources. Our sample contains 1843 ULX candidates associated with 951 different host galaxies, making it the largest ULX catalogue compiled to date. Of these, 689 sources are catalogued as ULX candidates for the first time. Our primary motivation is to identify new sources of interest for detailed follow-up studies, and within our catalogue we have already found one new extreme ULX candidate that has high S/N data in the archive: NGC 3044 ULX1. This source has a peak luminosity of LX,peak ∼ 1040 erg s−1, and the XMM–Newton spectrum of the source while at this peak flux is very similar to other, better-studied extreme ULXs that are now understood to be local examples of super-Eddington accretion. This likely indicates that NGC 3044 ULX1 is another source accreting at super-Eddington rates. We expect that this catalogue will be a valuable resource for planning future observations of ULXs – both with our current and future X-ray facilities – to further improve our understanding of this enigmatic population.