bluuebunny/crossref_metadata_2025_split huggingface dataset:
Invoking the virial theorem to understand the impact of (dry) mergers on the Mbh–σ relation
Authors: Graham Alister W 
Published: November 2022

ABSTRACT
While dry mergers can produce considerable scatter in the (black hole mass, Mbh)-(spheroid stellar mass, M*, sph) and Mbh-(spheroid half-light radius, Re, sph) diagrams, the virial theorem is used here to explain why the scatter about the Mbh–(velocity dispersion, σ) relation remains low in the face of such mergers. Its small scatter has been claimed as evidence of feedback from active galactic nuclei (AGNs). However, it is shown that galaxy mergers also play a significant role. The collision of two lenticular (S0) galaxies is expected to yield three types of merger product (a core-Sérsic S0, an ellicular ES,e or an elliptical E galaxy), depending on the remnant’s orbital angular momentum. It is shown that the major merger of two S0 galaxies with M*, sph ∼ 1011 M⊙ advances the system along a slope of ∼5 in the Mbh-σ diagram, while a major E+E galaxy merger moves a system slightly along a trajectory with a slope of ∼9. Mergers of lower-mass S0 galaxies with M*, sph ∼ 1010 M⊙ move slightly along a trajectory with a slope of ∼3, thereby further contributing to the steeper distribution for the E (and Es,e) galaxies in the Mbh-σ diagram, reported here to have a slope of 7.27 ± 0.91, compared to the S0 galaxies that have a slope of 5.68 ± 0.60. This result forms an important complement to the AGN feedback models like that from Silk & Rees, providing a more complete picture of galaxy/(black hole) co-evolution. It also has important implications for nanohertz gravitational-wave research.
Globular cluster ultraluminous X-ray sources in the furthest early-type galaxies
Authors: Thygesen Erica , Sun Yifan , Huang Jeff , Dage Kristen C , Zepf Stephen E , Kundu Arunav , Haggard Daryl , Maccarone Thomas J 
Published: November 2022

ABSTRACT
Ultraluminous X-ray sources (ULXs) in globular clusters (GCs) are low-mass X-ray binaries that achieve high X-ray luminosities through a currently uncertain accretion mechanism. Using archival Chandra and Hubble Space Telescope observations, we perform a volume-limited search (≲70 Mpc) of 21 of the most massive ($\gt 10^{11.5} \, \mathrm{M}_\odot$) early-type galaxies to identify ULXs hosted by GC candidates. We find a total of 34 ULX candidates above the expected background within five times the effective radius of each galaxy, with 10 of these ($\sim 29.4{{\ \rm per\ cent}}$) potentially hosted by a GC. A comparison of the spatial and luminosity distributions of these new candidate GC ULXs with previously identified GC ULXs shows that they are similar: both samples peak at LX ∼ a few × 1039 erg s−1 and are typically located within a few effective radii of their host galaxies.
High-resolution resonant portraits of a single-planet white dwarf system
Authors: Veras Dimitri , Georgakarakos Nikolaos , Dobbs-Dixon Ian 
Published: November 2022

ABSTRACT
The dynamical excitation of asteroids due to mean motion resonant interactions with planets is enhanced when their parent star leaves the main sequence. However, numerical investigation of resonant outcomes within post-main-sequence simulations is computationally expensive, limiting the extent to which detailed resonant analyses have been performed. Here, we combine the use of a high-performance computer cluster and the general semi-analytical libration width formulation of Gallardo, Beaugé & Giuppone in order to quantify resonant stability, strength, and variation instigated by stellar evolution for a single-planet system containing asteroids on both crossing and non-crossing orbits. We find that resonant instability can be accurately bound with only main-sequence values by computing a maximum libration width as a function of asteroid longitude of pericentre. We also quantify the relative efficiency of mean motion resonances of different orders to stabilize versus destabilize asteroid orbits during both the giant branch and white dwarf phases. The 4:1, 3:1, and 2:1 resonances represent efficient polluters of white dwarfs, and even when in the orbit-crossing regime, both the 4:3 and 3:2 resonances can retain small reservoirs of asteroids in stable orbits throughout giant branch and white dwarf evolution. This investigation represents a preliminary step in characterizing how simplified extrasolar Kirkwood gap structures evolve beyond the main sequence.
Multifilter observations of the complex periodic variations in eight pre-main sequence stars
Authors: Koen Chris 
Published: November 2022

ABSTRACT
Follow up time series photometry through various combinations of the BVRCIC filter set is presented for eight young stars. The complex periodic variability of seven of the stars was first discovered in TESS photometry, while one star was first observed by K2. The periods of the stars are short – 0.2–0.4 d. Reddening, effective temperatures, and bolometric magnitudes are estimated by fitting spectral energy distributions. The new photometry typically covers several cycles of variability. In some cases, photometry was obtained in more than one observing season. All new light curves differ from those obtained from satellite missions, in some cases substantially so. Amplitudes are almost always larger, the shorter the effective wavelength of the filter, but the relationship can be weak or non-monotonic. Given that all but one of the stars are in associations older than 10 Myr, it seems unlikely that protoplanetary discs play an important role in the complex variability patterns. Modelling of the wavelength dependence of amplitudes in terms of dust absorption in debris discs is explored. The conclusion is that excesses of small grains as compared with the average Galactic composition would be required.
Advective accretion disc-corona model with fallback for tidal disruption events
Authors: Mageshwaran T , Bhattacharyya Sudip 
Published: November 2022

ABSTRACT
Tidal disruption events (TDEs) show a correlation between the UV to X-ray spectral index and the Eddington ratio, with non-thermal X-ray emission at the low Eddington ratio. We consider the corona surrounding the accretion disc as a non-thermal X-ray source. We construct a time-dependent and non-relativistic advective accretion disc-corona model for TDEs. The infalling debris is assumed to form a seed disc in time tc, that evolves due to the mass gain from the infalling debris at the constant outer radius with a mass fallback rate $\dot{M}_{\rm fb}$ and the mass loss through accretion onto the black hole. The viscous stress in our model depends on gas (Pg) and total (Pt) pressures as $\tau _{r\phi } \propto P_\mathrm{g}^{1-\mu } P_\mathrm{t}^{\mu }$, where μ is a constant. We find that the mass accretion rate $\dot{M}_a$ evolves from Eddington to sub-Eddington accretion with a late-time evolution close to t−5/3, where t is the time. We find that the bolometric disc luminosity follows a late-time evolution close to t−5/3. The ratio of total X-ray luminosity from corona to bolometric disc luminosity increases with μ and increases at late times for μ ≠ 1. We obtain the X-ray blackbody temperature of the disc that agrees with the temperature from X-ray observations (∼ 105 K). We find the radiative efficiency of the disc increases with time and decreases for a disc when the corona is included. We have neglected the outflow, and our model is more applicable for near-to-sub-Eddington accretion and when $\dot{M}_{\rm fb}$ is sub-Eddington.
BASS XXXIX: Swift-BAT AGN with changing-look optical spectra
Authors: Temple Matthew J , Ricci Claudio , Koss Michael J , Trakhtenbrot Benny , Bauer Franz E , Mushotzky Richard , Rojas Alejandra F , Caglar Turgay , Harrison Fiona , Oh Kyuseok , Padilla Gonzalez Estefania , Powell Meredith C , Ricci Federica , Riffel Rogério , Stern Daniel , Urry C Megan 
Published: November 2022

ABSTRACT
Changing-look (CL) AGN are unique probes of accretion onto supermassive black holes (SMBHs), especially when simultaneous observations in complementary wavebands allow investigations into the properties of their accretion flows. We present the results of a search for CL behaviour in 412 Swift-BAT detected AGN with multiple epochs of optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS). 125 of these AGN also have 14–195  keV ultra-hard X-ray light curves from Swift-BAT which are contemporaneous with the epochs of optical spectroscopy. Eight CL events are presented for the first time, where the appearance or disappearance of broad Balmer line emission leads to a change in the observed Seyfert type classification. Combining with known events from the literature, 21 AGN from BASS are now known to display CL behaviour. Nine CL events have 14–195  keV data available, and five of these CL events can be associated with significant changes in their 14–195  keV flux from BAT. The ultra-hard X-ray flux is less affected by obscuration and so these changes in the 14–195 keV band suggest that the majority of our CL events are not due to changes in line-of-sight obscuration. We derive a CL rate of 0.7–6.2 per cent on 10–25 yr time-scales, and show that many transitions happen within at most a few years. Our results motivate further multiwavelength observations with higher cadence to better understand the variability physics of accretion onto SMBHs.
An accurate treatment of scattering and diffusion in piecewise power-law models for cosmic ray and radiation/neutrino transport
Authors: Hopkins Philip F 
Published: November 2022

ABSTRACT
A popular numerical method to model the dynamics of a ‘full spectrum’ of cosmic rays (CRs), also applicable to radiation/neutrino hydrodynamics, is to discretize the spectrum at each location/cell as a piecewise power law in ‘bins’ of momentum (or frequency) space. This gives rise to a pair of conserved quantities (e.g. CR number and energy) that are exchanged between cells or bins, which in turn give the update to the normalization and slope of the spectrum in each bin. While these methods can be evolved exactly in momentum-space (e.g. considering injection, absorption, continuous losses/gains), numerical challenges arise dealing with spatial fluxes, if the scattering rates depend on momentum. This has often been treated either by neglecting variation of those rates ‘within the bin,’ or sacrificing conservation – introducing significant errors. Here, we derive a rigorous treatment of these terms, and show that the variation within the bin can be accounted for accurately with a simple set of scalar correction coefficients that can be written entirely in terms of other, explicitly evolved ‘bin-integrated’ quantities. This eliminates the relevant errors without added computational cost, has no effect on the numerical stability of the method, and retains manifest conservation. We derive correction terms both for methods that explicitly integrate flux variables (e.g. two-moment or M1-like) methods, as well as single-moment (advection-diffusion, FLD-like) methods, and approximate corrections valid in various limits.
Chandra measurements of gas homogeneity and turbulence at intermediate radii in the Perseus Cluster
Authors: de Vries Martijn , Mantz Adam B , Allen Steven W , Morris R Glenn , Zhuravleva Irina , Canning Rebecca E A , Ehlert Steven R , Ogorzałek Anna , Simionescu Aurora , Werner Norbert 
Published: November 2022

ABSTRACT
We present a Chandra study of surface brightness fluctuations in the diffuse intracluster medium of the Perseus Cluster. Our study utilizes deep, archival imaging of the cluster core as well as a new mosaic of 29 short $\, 5\,$-ks observations extending in eight different directions out to radii of $r_{500} \sim 2.2\, r_{2500}$. Under the assumption that the distribution of densities at a given radius is log-normally distributed, two important quantities can be derived from the width of the log-normal density distribution on a given spatial scale: the density bias, that is equal to the square root of the clumping factor C; and the one-component turbulent velocity, vk,1D. We forward-model all contributions to the measured surface brightness, including astrophysical and particle background components, and account for the Poisson nature of the measured signal. Measuring the distribution of surface brightness fluctuations in 1 arcmin2 regions, spanning the radial range $0.3\rm {-}2.2\, r_{2500}$ ($7.8\rm {-}57.3\,$ arcmin), we find a small to moderate average density bias of around $3{{\ \rm per\ cent}}$ at radii below $1.6\, r_{2500}$. We also infer an average turbulent velocity at these radii of V1D &lt; 400 km s−1. Direct confirmation of our results on turbulent velocities inferred from surface brightness fluctuations should be possible using the X-ray calorimeter spectrometers to be flown aboard the XRISM and Athena observatories.
Intermediate-mass ratio inspirals in merging elliptical galaxies
Authors: Vázquez-Aceves Verónica , Amaro Seoane Pau , Kuvatova Dana , Makukov Maxim , Omarov Chingis , Yurin Denis 
Published: November 2022

ABSTRACT
Close encounters between two initially unbound objects can result in a binary system if enough energy is released as gravitational waves (GWs). We address the scenario in which such encounters occur in merging elliptical galaxies. There is evidence that elliptical galaxies can harbour intermediate-mass black holes (IMBHs). Therefore, these systems are potentially the breeding grounds of sources of GWs corresponding to inspiraling compact objects onto a massive black hole due to the dynamics, the large densities, and the number of compact remnants they contain. We show that this process is efficient for IMBHs with masses ranging from M ∈ (103, 105) M⊙ and results in the formation of intermediate-mass ratio inspirals (IMRIs). We consider a set of IMBHs and smaller black holes with masses m2 ∈ (10, 103) M⊙ to estimate the IMRI formation rate. We find rates ranging between 10−8 and 10−5 yr−1, and the IMRI formation rate per comoving volume in merging galaxies as a function of the redshift. The peak frequencies of the gravitational radiation emitted when these IMRIs are formed are within the detection band of space-borne detectors such as the Laser Interferometer Space Antenna (LISA) and TianQin; taking into account the observable volume of these detectors, the total amount of IMRI detections per year is significant.
Chemically peculiar stars in integrated light stellar population models and local group galaxies
Authors: Worthey Guy , Shi Xiang 
Published: November 2022

ABSTRACT
Integrated light models that incorporate common types of chemically peculiar (CP) stars are assembled using synthetic spectra. Selected spectral features encode significant age information for populations with ages ∼50 Myr &lt; age &lt; ∼2 Gyr. Due to the alleviation of template mismatch, the inclusion of CP star features in model spectra improves the accuracy of recovered stellar population parameters, but we are not able to show that new or unique age information can be extracted from the weak CP features compared to continuum fitting and strong-feature strengths, at least at the present state of the art. An age-extraction routine that recovers two- and three-burst age structures is employed to analyse the spectra of local group galaxies. NGC 224 (M 31) has a stellar population too old for the types of CP stars we examine. NGC 221 (M 32) also shows no CP spectral features. It appears to contain a component at age ∼1 Gyr at 1 per cent by mass in addition to its dominant 4.7 Gyr population. Unlike Sloan Digital Sky Survey galaxy spectrum averages, NGC 205 (M 110) contains no features due to mercury–manganese (HgMn) stars. This excludes the age range associated with HgMn production, and its near-nuclear spectrum is best fitted by a 68 ± 2 Myr population superimposed on an older population with a 1.85 ± 0.1 Gyr component. Both NGC 205 and NGC 221 have an ancient component whose mass is not easy to constrain given the overwhelming light dominance of the younger populations.
Tidally induced velocity gradients in the Milky Way dwarf spheroidal satellites
Authors: Martínez-García Alberto Manuel , del Pino Andrés , Aparicio Antonio 
Published: November 2022

ABSTRACT
We present a kinematic study of six dwarf spheroidal galaxies (dSph) satellites of the Milky Way (MW), namely Carina, Draco, Fornax, Sculptor, Sextans, and Ursa Minor. We combine proper motions (PMs) from the Gaia Data Release 3 (DR3) and line-of-sight velocities (vlos) from the literature to derive their 3D internal kinematics and to study the presence of internal velocity gradients. We find velocity gradients along the line-of-sight for Carina, Draco, Fornax, and Ursa Minor, at ≥1σ level of significance. The value of such gradients appears to be related to the orbital history of the dwarfs, indicating that the interaction with the MW is causing them. Dwarfs that are close to the MW and moving towards their orbits pericentres show, on average, larger velocity gradients. On the other hand, dwarfs that have recently left their orbits pericentres show no significant gradients. Lastly, dwarfs located at large Galactocentric distances show gradients with an intermediate intensity. Our results would indicate that the torque caused by the strong tidal forces exerted by the MW induces a strong velocity gradient when the dwarfs approach their orbits pericentres. During the pericentre passage, the rapid change in the forces direction would disrupt such gradient, which may steadily recover as the galaxies recede. We assess our findings by analysing dwarfs satellites from the TNG50 simulation. We find a significant increase in the intensity of the detected gradients as the satellites approach their pericentre, followed by a sharp drop as they abandon it, supporting our results for the dSphs of the MW.
Is the star-formation rate in z ∼ 6 quasars overestimated?
Authors: Di Mascia Fabio , Carniani Stefano , Gallerani Simona , Vito Fabio , Pallottini Andrea , Ferrara Andrea , Valentini Milena 
Published: November 2022

ABSTRACT
The large total infrared (TIR) luminosities (LTIR; ≳1012 L⊙) observed in z ∼ 6 quasars are generally converted into high star-formation rates (SFRs; $\gtrsim\!{10}^2~{\rm M}_{\odot }\, {\rm yr}^{-1}$) of their host galaxies. However, these estimates rely on the assumption that dust heating is dominated by stellar radiation, neglecting the contribution from the central active galactic nucleus (AGN). We test the validity of this assumption by combining cosmological hydrodynamic simulations with radiative transfer calculations. We find that, when AGN radiation is included in the simulations, the mass (luminosity)-weighted dust temperature in the host galaxies increases from T ≈ 50 K (T ≈ 70 K) to T ≈ 80 K (T ≈ 200 K), suggesting that AGN effectively heats the bulk of dust in the host galaxy. We compute the AGN-host galaxy SFR from the synthetic spectral energy distribution by using standard SFR – LTIR relations, and compare the results with the ‘true’ values in the simulations. We find that the SFR is overestimated by a factor of ≈3 (≳10) for AGN bolometric luminosities of Lbol ≈ 1012 L⊙ (≳1013 L⊙), implying that the SFRs of z ∼ 6 quasars can be overestimated by over an order of magnitude.
Self-organized criticality in solar GeV flares
Authors: Peng Fang-Kun , Wang Fa-Yin , Shu Xin-Wen , Hou Shu-Jin 
Published: November 2022

ABSTRACT
The Sun emits significant flares in X-ray, ultraviolet, and radio wavelengths. It is thought to originate from the magnetic reconnection activity, which is capable of accelerating particles to high energies. The magnetic process can be described by the avalanche model of self-organized criticality (SOC), and it is evidenced by the observation. Here, we study the frequency distribution of fluence, peak flux, and duration time for solar GeV flares detected first by Fermi-Large Area Telescope. Their cumulative distributions show a power-law behaviour. The exponents are also consistent with those derived from the observations at low-energy bands, and follow the predictions of the fractal-diffuse SOC model. In the meantime, the waiting time shows power-law distribution, and agrees a non-stationary Poission process. We then explore the correlation between energy (fluence) and duration time using a two-variable regression analysis. The correlation is found to be $T_{\rm Duration} \propto F_{\rm GeV}^{0.38\pm 0.08}$ with the solar GeV flare sample, which is comparable to that of the solar X-ray flares and gamma-ray bursts (GRBs) and could be understood in an SOC model. These facts suggest that, similar to the physical process accounting for the X-ray emission of solar flares and prompt emission of GRBs, magnetic reconnection may still dominate the energy-release process and particle acceleration for solar flares at GeV energies.
3D detection and characterization of ALMA sources through deep learning
Authors: Delli Veneri Michele , Tychoniec Łukasz , Guglielmetti Fabrizia , Longo Giuseppe , Villard Eric 
Published: November 2022

ABSTRACT
We present a deep learning (DL) pipeline developed for the detection and characterization of astronomical sources within simulated Atacama Large Millimeter/submillimeter Array (ALMA) data cubes. The pipeline is composed of six DL models: a convolutional autoencoder for source detection within the spatial domain of the integrated data cubes, a Recurrent Neural Network (RNN) for denoising and peak detection within the frequency domain, and four residual neural networks (ResNets) for source characterization. The combination of spatial and frequency information improves completeness while decreasing spurious signal detection. To train and test the pipeline, we developed a simulation algorithm able to generate realistic ALMA observations, i.e. both sky model and dirty cubes. The algorithm simulates always a central source surrounded by fainter ones scattered within the cube. Some sources were spatially superimposed in order to test the pipeline deblending capabilities. The detection performances of the pipeline were compared to those of other methods and significant improvements in performances were achieved. Source morphologies are detected with subpixel accuracies obtaining mean residual errors of 10−3 pixel (0.1 mas) and 10−1 mJy beam−1 on positions and flux estimations, respectively. Projection angles and flux densities are also recovered within 10 per cent of the true values for 80 and 73 per cent of all sources in the test set, respectively. While our pipeline is fine-tuned for ALMA data, the technique is applicable to other interferometric observatories, as SKA, LOFAR, VLBI, and VLTI.
Non-COVID-19 deaths in times of pandemic
Authors: Silverio-Murillo Adan , Balmori de la Miyar Jose Roberto , Martínez-Alfaro Alejandra 
Published: November 2022

Abstract

Background and objective
To investigate the effect of the COVID-19 pandemic on non-COVID-19 deaths in Mexico.

Methods
This study analyzes monthly administrative data on 15 different causes of death in Mexico from 2017 to 2020. The effects of the COVID-19 pandemic on non-COVID-19 deaths are conducted using a difference-in-differences methodology and an event study.

Results
The evidence shows mixed results. There is an increase in six causes of death: diabetes (36.8%), hypertension (25.8%), heart attacks (40.9%), bronchitis- asthma (24.2%), anemia (28.6%) and prostate cancer (21.4%). There is a decrease in two causes of death: traffic accidents (8.8%) and HIV (13.8%). There are null effects for seven causes of death: breast cancer, cerebrovascular disease, malnutrition, alcohol-related liver disease, renal insufficiency, homicides and suicides.

Conclusions
The COVID-19 pandemic affected non-COVID-19 deaths caused by diseases that require intensive healthcare services. Conversely, this pandemic reduced social interactions, which contributed to a decrease on deaths such as traffic accidents.