bluuebunny/crossref_metadata_2025_split huggingface dataset:
LIGO/Virgo Sources from Merging Black Holes in Ultradwarf Galaxies
Authors: Conselice Christopher J. , Bhatawdekar Rachana , Palmese Antonella , Hartley William G. 
Published: February 2020

Abstract
The origins of the black hole–black hole mergers discovered through gravitational waves with the LIGO/Virgo Collaboration are a mystery. We investigate the idea that some of these black holes originate from the centers of extremely low mass ultradwarf galaxies that have merged together in the distant past at z > 1. Extrapolating the central black hole/stellar mass ratio suggests that the black holes in these mergers could arise from galaxies of masses ∼105–106
M
⊙. We investigate whether these galaxies merge at a rate consistent with the observed black hole rate of ∼9.7–101 Gpc−3 yr−1 using the latest LIGO/Virgo results. We show that in the nearby universe the merger rate and number densities of ultradwarf galaxies are too low, by an order or magnitude, to produce these black hole mergers. However, by considering that the merger fraction, merger timescales, and the number densities of low-mass galaxies all conspire at z > 1–1.5 to increase the merger rate for these galaxies at higher redshifts, we argue that it is possible that these observed gravitational wave events could arise from black holes in the centers of low-mass galaxies. The major uncertainty in this calculation is the merger dynamical timescales for black holes in low-mass galaxies. Our results suggest that a very long black hole merger timescale of 4–7 Gyr is needed, consistent with an extended merger history. Further simulations of black hole merger timescales are needed to test this possibility; however, our theory can be tested by searching for host galaxies of gravitational wave events. Results from these searches will put limits on dwarf galaxy mergers and/or the presence and formation mechanisms of black holes through Population III stars in the lowest-mass galaxies.
Resolving Linear Polarization due to Emission and Extinction of Aligned Dust Grains on NGC 1333 IRAS4A with JVLA and ALMA
Authors: Ko 柯嘉 Chia-Lin 琳 , Liu 呂浩 Hauyu Baobab 宇 , Lai 賴詩 Shih-Ping 萍 , Ching 慶道 Tao-Chung 沖 , Rao Ramprasad , Girart Josep Miquel 
Published: February 2020

Abstract
We report high angular resolution observations of linearly polarized dust emission toward the Class 0 young stellar object NGC1333 IRAS4A (hereafter IRAS4A) using the Karl G. Jansky Very Large Array at K (11.5–16.7 mm), Ka (8.1–10.3 mm), and Q bands (6.3–7.9 mm), and using the Atacama Large Millimeter Array (ALMA) at Band 6 (1.3 mm) and Band 7 (0.85–0.89 mm). On 100–1000 au scales, all of these observations consistently trace the hourglass-shaped magnetic field topology as shown in the previous studies. In the innermost 100 au region of IRAS4A1, the polarization position angles (E field) detected at 6.3–16.7 mm are consistent; however, they are nearly 90° offset from those detected at 1.3 mm and 0.85–0.89 mm. Such a 90° offset may be explained by the inner ∼100 au area being optically thick at wavelengths shorter than ∼1.5 mm, whereby the observations probe the absorption of aligned dust against the weakly or unpolarized warm dust emission from the innermost region. This can also consistently explain why the highest angular resolution ALMA images at Band 7 show that the polarization percentage increases with dust brightness temperature in the inner ∼100 au region of IRAS4A1. Following this interpretation and assuming that the dust grains are aligned with the magnetic fields, the inferred magnetic field position angle based on the 90° rotated at 6.3–7.9 mm in the central peak of IRAS4A1 is ∼−22°, which is approximately consistent with the outflow direction of ∼−9°.
Diversity of Kilonova Light Curves
Authors: Kawaguchi Kyohei , Shibata Masaru , Tanaka Masaomi 
Published: February 2020

Abstract
We perform radiative transfer simulations for kilonova in various situations, including the cases of prompt collapse to a black hole from neutron star mergers, high-velocity ejecta possibly accelerated by magnetars, and a black hole–neutron star merger. Our calculations are done employing ejecta profiles predicted by numerical-relativity simulations and a new line list for all the r-process elements. We found that: (i) the optical emission for binary neutron stars promptly collapsing to a black hole would be fainter by ≳1–2 mag than that found in GW170817, while the infrared emission could be as bright as that in GW170817 if the post-merger ejecta is as massive as ≈0.01 M
⊙; (ii) the kilonova would be brighter than that observed in GW170817 for the case that the ejecta is highly accelerated by the electromagnetic energy injection from the remnant, but within a few days it would decline rapidly and the magnitude would become fainter than in GW170817; and (iii) the optical emission from a black hole–neutron star merger ejecta could be as bright as that observed in GW170817 for the case that sufficiently large amount of matter is ejected (≳0.02 M
⊙), while the infrared brightness would be brighter by 1–2 mag at the same time. We show that the difference in the ejecta properties would be imprinted in the differences in the peak brightness and time of peak. This indicates that we may be able to infer the type of the central engine for kilonovae by observation of the peak in the multiple band.
Large-scale Structures in the CANDELS Fields: The Role of the Environment in Star Formation Activity
Authors: Chartab Nima , Mobasher Bahram , Darvish Behnam , Finkelstein Steve , Guo Yicheng , Kodra Dritan , Lee Kyoung-Soo , Newman Jeffrey A. , Pacifici Camilla , Papovich Casey , Sattari Zahra , Shahidi Abtin , Dickinson Mark E. , Faber Sandra M. , Ferguson Henry C. , Giavalisco Mauro , Jafariyazani Marziye 
Published: February 2020

Abstract
We present a robust method, weighted von Mises kernel density estimation, along with boundary correction to reconstruct the underlying number density field of galaxies. We apply this method to galaxies brighter than Hubble Space Telescope

AB mag in the redshift range 0.4 ≤ z ≤ 5 in the five CANDELS fields (GOODS-N, GOODS-S, EGS, UDS, and COSMOS). We then use these measurements to explore the environmental dependence of the star formation activity of galaxies. We find strong evidence of environmental quenching for massive galaxies (M ≳ 1011
M
⊙) out to z ∼ 3.5 such that an overdense environment hosts ≳20% more massive quiescent galaxies than an underdense region. We also find that environmental quenching efficiency grows with stellar mass and reaches ∼60% for massive galaxies at z ∼ 0.5. The environmental quenching is also more efficient than stellar mass quenching for low-mass galaxies (M ≲ 1010
M
⊙) at low and intermediate redshifts (z ≲ 1.2). Our findings concur thoroughly with the “overconsumption” quenching model where the termination of cool gas accretion (cosmological starvation) happens in an overdense environment and the galaxy starts to consume its remaining gas reservoir in depletion time. The depletion time depends on the stellar mass and could explain the evolution of environmental quenching efficiency with stellar mass.
A Curious Case of Circular Polarization in the 25 GHz Methanol Maser Line toward OMC-1
Authors: Sarma A. P. , Momjian E. 
Published: February 2020

Abstract
We report the detection of a circular polarization signature in the Stokes V profile of a 25 GHz Class I CH3OH maser toward the high-mass star-forming region OMC-1. Such a feature usually constitutes a detection of the Zeeman effect. If due to a magnetic field in OMC-1, this would represent the first detection and discovery of the Zeeman effect in the 25 GHz Class I CH3OH maser. The feature in Stokes V is detected in two observations with different angular resolutions taken eight years apart with the Very Large Array; for our 2009 D-configuration observations, the fitted value for z

is 152 ± 12 Hz, where z is the Zeeman splitting factor and

is the line-of-sight magnetic field. For our 2017 C-configuration observations, the fitted value for z

= 149 ± 19 Hz, likely for the same maser spot. These correspond to

in the range 171–214 mG, depending on which hyperfine transition is responsible for the maser line. While these

values are high, they are not implausible. If the magnetic field increases in proportion to the molecular hydrogen density in shocked regions, then our detected fields predict values for the pre-shock magnetic field that are in agreement with observations. With

= 171–214 mG, the magnetic energy in the post-shocked regions where these 25 GHz Class I CH3OH masers occur would dominate over the kinetic energy density and be at least of the order of the pressure in the shock, implying that the magnetic field would exert significant influence over the dynamics of these regions.
Solitons and Turbulence in Solar Wind at 1 au: Multi-satellite Data and FDTD Simulations
Authors: Shah Asif , Rehman Saeed-Ur , Haque Qamar-UL , Mahmood Shahzad 
Published: February 2020

Abstract
During 2015 January 1–31 multi-satellite data at 1 au showed the propagation of single soliton pulses, the formation of soliton trains, and their ultimate development into the turbulence in solar wind magnetic field, density, speed, temperature, and dynamic pressure. This work is motivated by a basic research question: what are the differences in the conditions for excitation of soliton pulse, soliton train, and turbulence in the solar wind? To answer this question, a convective and dispersive system is considered and simulated via the finite difference time domain (FDTD) method. It is found that when a system is initially driven by a weak shock wave only a single soliton pulse will propagate. When the convection coefficient is smaller than or equal to the dispersion coefficient and system is driven by a strong shock then soliton trains are formed. The development of turbulence occurs when the convective coefficient dominates the dispersion coefficient and the system is driven by a stronger shock. Combining the findings of FDTD simulations with the Hall magnetohydrodynamic model, it is concluded that an enhanced interplanetary magnetic field in the magnetic sheath and the declining ion density after corotation interaction region interface provide favorable conditions for the solitons formation. Contrarily, the declining magnetic field in ejecta provides pertinent conditions for the evolution of Alfvénic turbulence. Our findings are critical for understanding the wave development into turbulence in solar wind.
Flash Ionization Signatures in the Type Ibn Supernova SN 2019uo
Authors: Gangopadhyay Anjasha , Misra Kuntal , Hiramatsu Daichi , Wang Shan-Qin , Hosseinzadeh Griffin , Wang Xiaofeng , Valenti Stefano , Zhang Jujia , Howell D. Andrew , Arcavi Iair , Anupama G. C. , Burke Jamison , Dastidar Raya , Itagaki Koichi , Kumar Brajesh , Kumar Brijesh , Li Long , McCully Curtis , Mo Jun , Pandey Shashi Bhushan , Pellegrino Craig , Sai Hanna , Sahu D. K. , Sanwal Pankaj , Singh Avinash , Singh Mridweeka , Zhang Jicheng , Zhang Tianmeng , Zhang Xinhan 
Published: February 2020

Abstract
We present photometric and spectroscopic observations of the type Ibn supernova (SN) 2019uo, the second ever SN Ibn with flash ionization (He ii, C iii, N iii) features in its early spectra. SN 2019uo displays a rapid post-peak luminosity decline of 0.1 mag day−1 similar to most of the SNe Ibn, but is fainter (

mag) than a typical SN Ibn and shows a color evolution that places it between SNe Ib and the most extreme SNe Ibn. SN 2019uo shows P-cygni He i features in the early spectra which gradually evolve and become emission dominated post peak. It also shows faster evolution in line velocities as compared to most other members of the type Ibn subclass. The bolometric light curve is fairly well described by a 56Ni + circumstellar interaction model.
Gamma-Ray Emission of 60Fe and 26Al Radioactivity in Our Galaxy
Authors: Wang W. , Siegert T. , Dai Z. G. , Diehl R. , Greiner J. , Heger A. , Krause M. , Lang M. , Pleintinger M. M. M. , Zhang X. L. 
Published: February 2020

Abstract
The isotopes 60Fe and 26Al originate from massive stars and their supernovae, reflecting ongoing nucleosynthesis in the Galaxy. We studied the gamma-ray emission from these isotopes at characteristic energies 1173, 1332, and 1809 keV with over 15 yr of SPI data, finding a line flux in 60Fe combined lines of

and the Al line flux of

above the background and continuum emission for the whole sky. Based on the exponential disk grid maps, we characterize the emission extent of 26Al to find scale parameters

and

kpc; however, the 60Fe lines are too weak to spatially constrain the emission. Based on a point-source model test across the Galactic plane, the 60Fe emission would not be consistent with a single strong point source in the Galactic center or somewhere else, providing a hint of a diffuse nature. We carried out comparisons of emission morphology maps using different candidate source tracers for both 26Al and 60Fe emissions and suggest that the 60Fe emission is more likely to be concentrated toward the Galactic plane. We determine the 60Fe/26Al γ-ray flux ratio at 18.4% ± 4.2% when using a parameterized spatial morphology model. Across the range of plausible morphologies, it appears possible that 26Al and 60Fe are distributed differently in the Galaxy. Using the best-fitting maps for each of the elements, we constrain flux ratios in the range 0.2–0.4. We discuss the implications for massive star models and their nucleosynthesis.
Spatially Resolved Analysis of Neutral Winds, Stars, and Ionized Gas Kinematics with MEGARA/GTC: New Insights on the Nearby Galaxy UGC 10205
Authors: Catalán-Torrecilla C. , Castillo-Morales Á. , Gil de Paz A. , Gallego J. , Carrasco E. , Iglesias-Páramo J. , Cedazo R. , Chamorro-Cazorla M. , Pascual S. , García-Vargas M. L. , Cardiel N. , Gómez-Alvarez P. , Pérez-Calpena A. , Martínez-Delgado I. , Dullo B. T. , Coelho P. , Bruzual G. , Charlot S. 
Published: February 2020

Abstract
We present a comprehensive analysis of the multiphase structure of the interstellar medium (ISM) and the stellar kinematics in the edge-on nearby galaxy UGC 10205 using integral field spectroscopy (IFS) data taken with Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía (MEGARA) at the GTC. We explore both the neutral and the ionized gas phases using the interstellar Na i D doublet absorption (LR−V setup, R ∼ 6000) and the Hα emission line (HR−R setup, R ∼ 18000), respectively. The high-resolution data show the complexity of the Hα emission-line profile revealing the detection of up to three kinematically distinct gaseous components. Despite of this fact, a thin-disk model is able to reproduce the bulk of the ionized gas motions in the central regions of UGC 10205. The use of asymmetric drift corrections is needed to reconciliate the ionized and the stellar velocity rotation curves. We also report the detection of outflowing neutral gas material blueshifted by ∼ 87 km s−1. The main physical properties that describe the observed outflow are a total mass M
out = (4.55 ± 0.06) × 107
M
☉ and a cold-gas mass outflow rate

M

̇

out

=
0.78
±
0.03

M
☉ yr−1. This work points out the necessity of exploiting high-resolution IFS data to understand the multiphase components of the ISM and the multiple kinematical components in the central regions of nearby galaxies.
Microlensing Analysis for the Gravitational Lens Systems SDSS0924+0219, Q1355-2257, and SDSS1029+2623
Authors: Rojas K. , Motta V. , Mediavilla E. , Jiménez-Vicente J. , Falco E. , Fian C. 
Published: February 2020

Abstract
We use spectroscopic observations of the gravitationally lensed systems SDSS0924+0219(BC), Q1355-2257(AB), and SDSS1029+2623(BC) to analyze microlensing and dust extinction in the observed components. We detect chromatic microlensing effects in the continuum and microlensing in the broad emission line profiles of the systems SDSS0924+0219(BC) and Q1355-2257(AB). Using magnification maps to simulate microlensing and modeling the emitting region as a Gaussian intensity profile with size r

s
∝ λ

p
, we obtain the probability density functions for a logarithmic size prior to

. In the case of SDSS0924+0219, we obtain

lt-d (at 1σ), which is larger than the range of other estimates, and p = 0.8 ± 0.2 (at 1σ), which is smaller than predicted by the thin disk theory, but still in agreement with previous results. In the case of Q1355-2257 we obtain (at 1σ)

lt-d, which is also larger than the theoretical prediction, and p = 2.0 ± 0.7, which is in agreement with the theory within errors. SDSS1029+2326 spectra show evidence of extinction, probably produced by a galaxy in the vicinity of image C. Fitting an extinction curve to the data we estimate ΔE ∼ 0.2 in agreement with previous results. We found no evidence of microlensing for this system.
Gamma Rays from Kilonova: A Potential Probe of r-process Nucleosynthesis
Authors: Korobkin Oleg , Hungerford Aimee M. , Fryer Christopher L. , Mumpower Matthew R. , Misch G. Wendell , Sprouse Trevor M. , Lippuner Jonas , Surman Rebecca , Couture Aaron J. , Bloser Peter F. , Shirazi Farzane , Even Wesley P. , Vestrand W. Thomas , Miller Richard S. 
Published: February 2020

Abstract
The mergers of compact binaries with at least one neutron star component are the potential leading sites of the production and ejection of r-process elements. Discoveries of galactic binary pulsars, short gamma-ray bursts, and gravitational-wave detections have all been constraining the rate of these events, while the gravitational wave plus broadband electromagnetic coverage of binary neutron star merger (GW170817) has also placed constraints on the properties (mass and composition) of the merger ejecta. But uncertainties and ambiguities in modeling the optical and infrared emission make it difficult to definitively measure the distribution of heavy isotopes in these mergers. In contrast, gamma rays emitted in the decay of these neutron-rich ejecta may provide a more direct measurement of the yields. We calculate the gamma production in remnants of neutron star mergers, considering two epochs: a kilonova epoch, lasting about two weeks, and a much later epoch of tens and hundreds of thousands of years after the merger. For the kilonova epoch, when the expanding ejecta is still only partially transparent to gamma radiation, we use 3D radiative transport simulations to produce the spectra. We show that the gamma-ray spectra associated with beta- and alpha-decay provide a fingerprint of the ejecta properties and, for a sufficiently nearby remnant, may be detectable, even for old remnants. We compare our gamma spectra with the potential detection limits of next generation detectors, including the Lunar Occultation Explorer (LOX), the All-sky Medium Energy Gamma-ray Observatory (AMEGO), and the Compton Spectrometer and Imager (COSI). We show that fission models can be discriminated via the presence of short-lived fission fragments in the remnant spectra.
Deciphering the Local Interstellar Spectra of Secondary Nuclei with the Galprop/Helmod Framework and a Hint for Primary Lithium in Cosmic Rays
Authors: Boschini M. J. , Torre S. Della , Gervasi M. , Grandi D. , Jøhannesson G. , Vacca G. La , Masi N. , Moskalenko I. V. , Pensotti S. , Porter T. A. , Quadrani L. , Rancoita P. G. , Rozza D. , Tacconi M. 
Published: February 2020

Abstract
Local interstellar spectra (LIS) of secondary cosmic-ray (CR) nuclei, lithium, beryllium, boron, and partially secondary nitrogen, are derived in the rigidity range from 10 MV to ∼200 TV using the most recent experimental results combined with state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. The lithium spectrum appears somewhat flatter at high energies compared to other secondary species, which may imply a primary lithium component. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. An iterative maximum-likelihood method is developed that uses GALPROP-predicted LIS as input to HelMod, which provides the modulated spectra for specific time periods of the selected experiments for the model-data comparison. The proposed LIS accommodates the low-energy interstellar spectra measured by Voyager 1, the High Energy Astrophysics Observatory-3 (HEAO-3), and the Cosmic Ray Isotope Spectrometer on board of the Advanced Composition Explorer (ACE/CRIS), as well as the high-energy observations by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), Alpha Magnetic Spectrometer-02 (AMS-02), and earlier experiments that are made deep in the heliosphere. The interstellar and heliospheric propagation parameters derived in this study are consistent with our earlier results for propagation of CR protons, helium, carbon, oxygen, antiprotons, and electrons.
Implications from Late-time X-Ray Detections of Optically Selected Tidal Disruption Events: State Changes, Unification, and Detection Rates
Authors: Jonker P. G. , Stone N. C. , Generozov A. , Velzen S. van , Metzger B. 
Published: February 2020

Abstract
We present Chandra X-ray observations of four optically selected tidal disruption events (TDEs) obtained 4–9 yr after discovery. Three sources were detected with luminosities between 9 × 1040 and 3 × 1042 erg s−1. The spectrum of PTF09axc is consistent with a power law of index 2.5 ± 0.1, whereas the spectrum of PTF09ge is very soft. The power-law spectrum of PTF09axc and prior literature findings provide evidence that TDEs transition from an early-time soft state to a late-time hard state many years after disruption. We propose that the time to peak luminosity for optical and X-ray emission may differ substantially in TDEs, with X-rays being produced or becoming observable later. This delay helps explain the differences in observed properties such as L
opt/L
X of optically and X-ray-selected TDEs. We update TDE rate predictions for the eROSITA instrument: it ranges from 3 to 990 yr−1, depending sensitively on the distribution of black hole spins and the time delay between disruption and peak X-ray brightness. We further predict an asymmetry in the number of retrograde and prograde disks in samples of optically and X-ray-selected TDEs. The details of the observational biases can contribute to observed differences between optically and X-ray-selected TDEs (with optically selected TDEs being fainter in X-rays for retrograde TDE disks).
What is the Solar Wind Frame of Reference?
Authors: Němeček Zdeněk , Ďurovcová Tereza , Šafránková Jana , Němec František , Matteini Lorenzo , Stansby David , Janitzek Nils , Berger Lars , Wimmer-Schweingruber Robert F. 
Published: February 2020

Abstract
Various solar wind ion species move with different speeds and theoretical considerations as well as limited observations in a region close to the Sun show that heavy solar wind ions tend to flow faster than protons, at least in less-aged fast solar wind streams. The solar wind flow carries the frozen-in interplanetary magnetic field (IMF) and this situation evokes three related questions: (i) what is the proper solar wind speed, (ii) is this speed equal to the speed of the dominant component, whatever that may be, and (iii) what is the speed of the magnetic field? We show that simple theoretical considerations based on the MHD approximation as well as on the dynamics of charged particles in electric and magnetic fields suggest that the IMF velocity of motion (de Hoffmann–Teller (HT) velocity) would be deliberated as the velocity appropriate for solar wind studies. Our analysis based on the Wind, Helios, ACE, and SOHO observations of differential streaming of solar wind populations shows that their energy is conserved in the HT frame. On the other hand, the noise and temporal resolution of the data do not allow us to decide whether the total momentum is also conserved in this frame.