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we present the first x-ray polarimetric study of the dipping accreting neutron star 4u 1624$-$49 with the imaging x-ray polarimetry explorer (ixpe). we report a detection of polarization in the non-dip time intervals with a confidence level of 99.99%. we find an average polarization degree (pd) of $3.1\pm0.7$% and a po... | x-ray polarimetry of the dipping accreting neutron star 4u 1624-49 |
we identify and characterize a milky way-like realization from the auriga simulations with two consecutive massive mergers $\sim 2$ gyr apart at high redshift, comparable to the reported kraken and gaia-sausage-enceladus. the kraken-like merger (z = 1.6, $m_{\rm tot}=8\times 10^{10}\, \rm {m_{\odot }}$) is gas-rich, de... | the impact of two massive early accretion events in a milky way-like galaxy: repercussions for the buildup of the stellar disc and halo |
we present nustar observations of neutron star (ns) low-mass x-ray binaries: 4u 1636-53, gx 17+2, and 4u 1705-44. we observed 4u 1636-53 in the hard state, with an eddington fraction, {f}{edd}, of 0.01; gx 17+2 and 4u 1705-44 were in the soft state with fractions of 0.57 and 0.10, respectively. each spectrum shows evid... | a hard look at the neutron stars and accretion disks in 4u 1636-53, gx 17+2, and 4u 1705-44 with nustar |
context. protostars grow from the first formation of a small seed and subsequent accretion of material. recent theoretical work has shown that the pre-main-sequence (pms) evolution of stars is much more complex than previously envisioned. instead of the traditional steady, one-dimensional solution, accretion may be epi... | revisiting the pre-main-sequence evolution of stars. i. importance of accretion efficiency and deuterium abundance |
stars that pass too close to a super-massive black hole may be disrupted by strong tidal forces. ogle16aaa is one such tidal disruption event (tde) which rapidly brightened and peaked in the optical/uv bands in early 2016 and subsequently decayed over the rest of the year. ogle16aaa was detected in an xmm-newton x-ray ... | rapid late-time x-ray brightening of the tidal disruption event ogle16aaa |
stellar tidal disruption events (tdes) are typically discovered by transient emission due to accretion or shocks of the stellar debris. yet this luminous flare can be reprocessed by gas or dust that inhabits a galactic nucleus, resulting in multiple reverberation signals. nuclear dust heated by the tde will lead to an ... | reverberation in tidal disruption events: dust echoes, coronal emission lines, multi-wavelength cross-correlations, and qpos |
models for tidal disruption events (tdes) in which a supermassive black hole disrupts a star commonly assume that the highly eccentric streams of bound stellar debris promptly form a circular accretion disc at the pericentre scale. however, the bolometric peak luminosity of most tde candidates, ∼ 1044 erg s- 1, implies... | elliptical accretion and low luminosity from high accretion rate stellar tidal disruption events |
we study tidal features around galaxies in the resolved spectroscopy of a local volume (resolve) survey. our sample consists of 1048 resolve galaxies that overlap with the decam legacy survey, which reaches an r-band 3σ depth of ∼27.9 mag arcsec-2 for a 100 arcsec2 feature. images were masked, smoothed, and inspected f... | the origin of faint tidal features around galaxies in the resolve survey |
the driving of turbulence in galaxies is deeply connected with the physics of feedback, star formation, outflows, accretion, and radial transport in disks. the velocity dispersion of gas in galaxies therefore offers a promising observational window into these processes. however, the relative importance of each of these... | gas accretion can drive turbulence in galaxies |
the continuum-fitting and the iron line methods are currently the two leading techniques for probing the strong gravity region around accreting black holes. in the present work, we test the kerr black hole hypothesis with the stellar-mass black hole in grs 1915+105 by analyzing five disk-dominated rxte spectra and one ... | testing the kerr black hole hypothesis with the continuum-fitting and the iron line methods: the case of grs 1915+105 |
it is thought that the spacetime metric around astrophysical black holes is well described by the kerr solution of einstein’s gravity. however, robust observational evidence of the kerr nature of these objects is still lacking. here we fit the x-ray spectrum of the stellar-mass black hole in gs 1354-645 with a disk ref... | a study of the strong gravity region of the black hole in gs 1354-645 |
we present a study of the connection among black hole accretion, star formation, and galaxy morphology at z≤slant 2.5. we focus on active galactic nuclei (agns) selected by their mid-ir power-law emission. by fitting optical to far-ir photometry with state-of-the-art spectral energy distribution (sed) techniques, we de... | infrared selection of obscured active galactic nuclei in the cosmos field |
we have used deep muse observations to perform a stellar-kinematic and population analysis of fcc 153 and fcc 177, two edge-on s0 galaxies in the fornax cluster. the geometrical definition of the different structural components of these two galaxies allows us to describe the nature of their thick disks. these are both ... | the fornax 3d project: thick disks in a cluster environment |
we aim to understand the effect of stellar evolution on the evolution of protoplanetary disks. we focus in particular on the disk evolution around intermediate-mass (im) stars, which evolve more rapidly than low-mass ones. we numerically solve the long-term evolution of disks around 0.5-5 m⊙ stars considering viscous a... | photoevaporative dispersal of protoplanetary disks around evolving intermediate-mass stars |
relativistic reflection features are commonly observed in the x-ray spectra of stellar-mass and supermassive black holes and originate from illumination of the inner part of the accretion disc by a hot corona. all the available relativistic reflection models assume that the disc is infinitesimally thin and the inner ed... | reflection spectra of thick accretion discs |
the examination of long-term (1979-2020) photometric observations of ss433 enabled us to discover a non-zero orbital eccentricity of e = 0.05 ± 0.01. we have also found evidence for a secular increase in the orbital period at a rate of $\dot{p}_\mathrm{b}=(1.0\pm 0.3)\times 10^{-7}$ s s-1. the binary orbital period inc... | discovery of orbital eccentricity and evidence for orbital period increase of ss433 |
we present a new analysis of nustar and suzaku observations of the black hole cygnus x-1 in the intermediate state. the analysis is performed using kerrc, a new model for analyzing spectral and spectropolarimetric x-ray observations of black holes. kerrc builds on a large library of simulated black holes in x-ray binar... | new constraints on the spin of the black hole cygnus x-1 and the physical properties of its accretion disk corona |
the conditions leading to the formation of the most massive o-type stars are still an enigma in modern astrophysics. to assess the physical conditions of high-mass protostars in their main accretion phase, here we present a case study of a young massive clump selected from the atlasgal survey, g328.2551-0.5321. the sou... | search for high-mass protostars with alma revealed up to kilo-parsec scales (sparks). i. indication for a centrifugal barrier in the environment of a single high-mass envelope |
continuum and reflection spectral models have each been widely employed in measuring the spins of accreting black holes. however, the two approaches have not been implemented together in a photon-conserving, self-consistent framework. we develop such a framework using the black hole x-ray binary gx 339-4 as a touchston... | self-consistent black hole accretion spectral models and the forgotten role of coronal comptonization of reflection emission |
recently, k2 and tess have discovered transiting planets with radii between ∼5 and 10 r⊕ around stars with ages <100 myr. these young planets are likely to be the progenitors of the ubiquitous super-earths/sub-neptunes, which are well studied around stars with ages ≳1 gyr. the formation and early evolution of super-... | constraining the entropy of formation from young transiting planets |
galaxies with milky way-like stellar masses have a wide range of bulge and black hole masses; in turn, these correlate with other properties such as star formation history. while many processes may drive bulge formation, major and minor mergers are expected to play a crucial role. stellar halos offer a novel and robust... | galaxies grow their bulges and black holes in diverse ways |
3d hydrodynamic numerical simulations have demonstrated that the structure of a protoplanetary disc may be strongly affected by a planet orbiting in a plane that is misaligned to the disc. when the planet is able to open a gap, the disc is separated into an inner, precessing disc and an outer disc with a warp. in this ... | scattered light shadows in warped protoplanetary discs |
we argue that resonant friction has a dramatic effect on a disc whose rotation direction is misaligned with that of its host nuclear star cluster. the disc's gravity causes gravitational perturbation of the cluster that in turn exerts a strong torque back onto the disc. we argue that this torque may be responsible for ... | resonant friction on discs in galactic nuclei |
the iron kα line commonly observed in the x-ray spectrum of both stellar-mass and supermassive black hole candidates is produced by the illumination of a cold accretion disk by a hot corona. in this framework, the activation of a new flaring region in the hot corona imprints a time variation on the iron line spectrum. ... | using iron line reverberation and spectroscopy to distinguish kerr and non-kerr black holes |
we present the results from a dense multwavelength [optical/uv, near-infrared (ir), and x-ray] follow-up campaign of the nuclear transient at 2017gge, covering a total of 1698 d from the transient's discovery. the bolometric light curve, the blackbody temperature and radius, the broad h and he i λ5876 emission lines an... | the nuclear transient at 2017gge: a tidal disruption event in a dusty and gas-rich environment and the awakening of a dormant smbh |
these notes introduce and review some of the physical principles underlying the theory of astrophysical accretion, emphasizing the central roles of angular momentum transport, angular momentum loss, and radiative cooling in determining the structure and evolution of accretion flows. additional topics covered include th... | lecture notes on accretion disk physics |
the gas needed to sustain star formation in galaxies is supplied by the circumgalactic medium (cgm), which in turn is affected by accretion from large scales. in a series of two papers, we examine the interplay between a galaxy's ambient cgm and central star formation within the context of the large-scale environment. ... | from large-scale environment to cgm angular momentum to star forming activities - ii. quenched galaxies |
we analyse all available observations of gx 339-4 by xmm-newton in the hard spectral state. we jointly fit the spectral data by comptonization and the currently best reflection code, relxill. we consider in detail a contribution from a standard blackbody accretion disc, testing whether its inner radius can be set equal... | spectral analysis of the xmm-newton data of gx 339-4 in the low/hard state: disc truncation and reflection |
in order to assess the impact of the environment on the formation and evolution of galaxies, accurate assembly histories of such galaxies are needed. however, these measurements are observationally difficult owing to the diversity of formation paths that lead to the same present-day state of a galaxy. in this work, we ... | the fornax3d project: assembly histories of lenticular galaxies from a combined dynamical and population orbital analysis |
we present simulations of galaxy formation, based on the gadget-3 code, in which a sub-resolution model for star formation and stellar feedback is interfaced with a new model for active galactic nucleus (agn) feedback. our sub-resolution model describes a multiphase interstellar medium (ism), accounting for hot and col... | impact of agn feedback on galaxies and their multiphase ism across cosmic time |
future very-large-area x-ray instruments (for which the effective area is larger than > 3 m2) will be able to measure the frequencies of quasi-periodic oscillations (qpos) observed in the x-ray flux from accreting compact objects with sub-percent precision. if correctly modeled, qpos can provide a novel way to test ... | geodesic models of quasi-periodic-oscillations as probes of quadratic gravity |
we study a sample of eight massive galaxies that are extreme outliers (3-5σ) in the {m}\bullet - mbulge local scaling relation. two of these galaxies are confirmed to host extremely large super-massive black holes (smbhs), whereas the virial mass estimates for the other six are also consistent with having abnormally la... | massive relic galaxies challenge the co-evolution of super-massive black holes and their host galaxies |
we present the results of a semicoherent search for continuous gravitational waves from the low-mass x-ray binary scorpius x-1, using data from the first advanced ligo observing run. the search method uses details of the modeled, parametrized continuous signal to combine coherently data separated by less than a specifi... | upper limits on gravitational waves from scorpius x-1 from a model-based cross-correlation search in advanced ligo data |
recent observations show that the metallicity z blr of the broad-line region (blr) in active galactic nuclei (agns) is solar to supersolar, which is positively correlated with the mass of supermassive black holes (m bh) and does not evolve with the redshift up to z ~ 7. we revisit the m bh-z blr correlation with more a... | in situ star formation in accretion disks and explanation of correlation between the black hole mass and metallicity in active galactic nuclei |
we present an analytical and numerical study of a system composed of a stellar binary pair and a massless, locally isothermal viscous accretion disk that is coplanar to the binary orbital plane. analytically, we study the effect of the binary's gravitational potential over short timescales through the study of stabilit... | analytical and numerical analysis of circumbinary disk dynamics -- i: coplanar systems |
numerical general relativistic radiative magnetohydrodynamic simulations of accretion discs around a stellar-mass black hole with a luminosity above 0.5 of the eddington value reveal their stratified, elevated vertical structure. we refer to these thermally stable numerical solutions as puffy discs. above a dense and g... | observational properties of puffy discs: radiative grmhd spectra of mildly sub-eddington accretion |
subarcsecond images of the rotational line emission of cs and so have been obtained toward the class i protostar iras 04365+2535 in tmc-1a with alma. a compact component around the protostar is clearly detected in the cs and so emission. the velocity structure of the compact component of cs reveals infalling-rotating m... | subarcsecond analysis of the infalling-rotating envelope around the class i protostar iras 04365+2535 |
type-c quasi-periodic oscillations (qpos) are the low-frequency qpos most commonly observed during the hard spectral state of x-ray binary systems. the leading model for these qpos is the lense-thirring precession of a hot geometrically thick accretion flow that is misaligned with respect to the black hole spin axis. h... | effect of geometrically thin discs on precessing, thick flows: relevance to type-c qpos |
context. the water snow line divides dry and icy solid material in protoplanetary disks. it has been thought to significantly affect planet formation at all stages. if dry particles break up more easily than icy ones, then the snow line causes a traffic jam because small grains drift inward at lower speeds than larger ... | gas accretion damped by dust back-reaction at the snow line |
atoll sources are accreting neutron star (ns) low-mass x-ray binaries. we present a spectral analysis of four persistent atoll sources (gx 3+1, 4u 1702-429, 4u 0614+091, and 4u 1746-371) observed for ∼20 ks each with nustar to determine the extent of the inner accretion disk. these sources range from an apparent lumino... | nustar observations of the accreting atolls gx 3+1, 4u 1702-429, 4u 0614+091, and 4u 1746-371 |
in the canonical model for tidal disruption events (tdes), the stellar debris circularizes quickly to form an accretion disc of size about twice the orbital pericentre of the star. most tdes and candidates discovered in the optical/ultraviolet have broad optical emission lines with complex and diverse profiles of puzzl... | a large accretion disc of extreme eccentricity in the tde asassn-14li |
we report on srg/erosita, ztf, asas-sn, las cumbres, neowise-r, and swift xrt/uvot observations of the unique ongoing event at 2019avd, located in the nucleus of a previously inactive galaxy at z = 0.029. erosita first observed at 2019avd on 2020-04-28 during its first all sky survey, when it was detected as an ultra-s... | at 2019avd: a novel addition to the diverse population of nuclear transients |
we have for the first time identified the early stellar disk in the milky way by using a combination of elemental abundances and kinematics. using data from apogee dr17 and gaia we select stars in the mg-mn-al-fe plane with elemental abundances indicative of an accreted origin and find stars with both halo-like and dis... | the metal-weak milky way stellar disk hidden in the gaia-sausage-enceladus debris: the apogee dr17 view |
scalar-tensor-vector gravity (stvg) is an alternative theory of gravitation that has successfully explained the rotation curves of nearby galaxies, the dynamics of galactic clusters, and cosmological data without dark matter, but has hardly been tested in the strong gravity regime. in this work, we aim at building radi... | accretion disks around black holes in scalar-tensor-vector gravity |
we present results from two-dimensional, general relativistic, viscous, radiation hydrodynamic numerical simulations of shakura-sunyaev thin disks accreting onto stellar-mass schwarzschild black holes. we consider cases on both the gas- and radiation-pressure-dominated branches of the thermal equilibrium curve, with ma... | relativistic, viscous, radiation hydrodynamic simulations of geometrically thin disks. i. thermal and other instabilities |
the stellar mass, size, and rotational velocity of galactic discs all grow from redshift ∼2 to the present by amounts that are estimated from observationally derived scaling relations. the product of these three quantities, the angular momentum of stellar discs, is then estimated to grow by a remarkably large factor, b... | on the angular momentum history of galactic discs |
in the first paper of this series, we proposed a model-independent framework for characterising the architecture of planetary systems at the system level. there are four classes of planetary system architecture: similar, mixed, anti-ordered, and ordered. in this paper, we investigate the formation pathways leading to t... | framework for the architecture of exoplanetary systems. ii. nature versus nurture: emergent formation pathways of architecture classes |
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... | population iii star formation in an x-ray background - ii. protostellar discs, multiplicity, and mass function of the stars |
we present a detailed analysis of the structure of the local group flocculent spiral galaxy m33, as measured using the panchromatic hubble andromeda treasury triangulum extended region (phatter) survey. leveraging the multiwavelength coverage of phatter, we find that the oldest populations are dominated by a smooth exp... | the panchromatic hubble andromeda treasury: triangulum extended region (phatter). v. the structure of m33 in resolved stellar populations |
x-ray polarimetry missions like imaging x-ray polarimetry explorer will be able to measure for the first time the polarization properties of accreting, weakly magnetized neutron stars in low-mass x-ray binaries. in this work, we present simulations of the expected x-ray polarized signal, including the coronal emission ... | polarization properties of weakly magnetized neutron stars in low-mass x-ray binaries |
high-mass stars have generally been assumed to accrete most of their mass while already contracted onto the main sequence, but this hypothesis has not been observationally tested. we present alma observations of a 3× 1.5 pc area in the w51 high-mass star-forming complex. we identify dust continuum sources and measure t... | thermal feedback in the high-mass star- and cluster-forming region w51 |
polarization of the ≳ 400 kev hard tail of the microquasar cygnus x-1 has been independently reported by integral/imager on board the integral satellite (ibis), and integral/spectrometer on integral and interpreted as emission from a compact jet. these conclusions were, however, based on the accumulation of all integra... | spectral state dependence of the 0.4-2 mev polarized emission in cygnus x-1 seen with integral/ibis, and links with the ami radio data |
we explore the linear stability of astrophysical discs exhibiting vertical shear, which arises when there is a radial variation in the temperature or entropy. such discs are subject to a `vertical-shear instability', which recent non-linear simulations have shown to drive hydrodynamic activity in the mri-stable regions... | on the vertical-shear instability in astrophysical discs |
cluster substructure and ram pressure stripping in individual galaxies are among the primary pieces of evidence for the ongoing growth of galaxy clusters as they accrete galaxies and groups from their surroundings. we present a multiwavelength study of the center of the hydra i galaxy cluster, including exquisite new m... | ngc 3314a/b and ngc 3312: ram pressure stripping in hydra i cluster substructure |
the ultraluminous x-ray source (ulx) population is known to contain neutron stars (ns), but the relative number of these compared to black hole (bh) primaries is unknown. assuming classical supercritical accretion and resultant geometrical beaming, we show that the observed population ratio can be predicted from the me... | predicting ultraluminous x-ray source demographics from geometrical beaming |
the formation and evolution of galaxies are highly dependent on the dynamics of stars and gas, which is governed by the underlying law of gravity. to investigate how the formation and evolution of galaxies take place in milgromian gravity (mond), we present full hydrodynamical simulations with the phantom of ramses cod... | the formation of exponential disk galaxies in mond |
we show how wet major mergers can create disc galaxies in a cosmological context, using the illustris simulation. we select a sample of 38 disc galaxies having experienced a major merger in their history with no subsequent significant minor merger, and study how they transform into discs after the merger. in agreement ... | disc galaxies formed from major mergers in illustris |
deeply embedded protostars are actively fed from their surrounding envelopes through their protostellar disc. the physical structure of such early discs might be different from that of more evolved sources due to the active accretion. we present 1.3 and 3 mm alma continuum observations at resolutions of 6.5 and 12 au, ... | the young protostellar disc in iras 16293-2422 b is hot and shows signatures of gravitational instability |
we present a new method to derive binary inclinations in quiescent black hole (bh) x-ray transients (xrts), based on the depth of the trough (t) from double-peaked h α emission profiles arising in accretion discs. we find that the inclination angle (i) is linearly correlated with t in phase-averaged spectra with suffic... | a correlation between h α trough depth and inclination in quiescent x-ray transients: evidence for a low-mass black hole in gro j0422+32 |
a star crossing the tidal radius of a supermassive black hole will be spectacularly ripped apart with an accompanying burst of radiation. a few tens of such tidal disruption events have now been identified in optical wavelengths, but the exact origin of the strong optical emission remains inconclusive. here we report p... | an asymmetric electron-scattering photosphere around optical tidal disruption events |
we present a theoretical model for the evolution of mass, angular momentum and size of galaxy discs and bulges, and we implement it into the semi-analytic galaxy formation code, semi-analytic galaxy evolution. the model follows both secular and violent evolutionary channels, including smooth accretion, disc instabiliti... | the growth of discs and bulges during hierarchical galaxy formation - i. fast evolution versus secular processes |
intermediate-mass black holes (imbhs), with masses between 100-105 m ⊙, fill the gap between stellar mass black holes and the supermassive black holes that reside in galaxy centers. while imbhs are crucial to our understanding of black hole seed formation, black holes of less than ≈104 m ⊙ have so far eluded detection ... | the hunt for intermediate-mass black holes in the jwst era |
an otherwise dormant supermassive black hole (smbh) in a galactic nucleus flares up when it tidally disrupts a star passing by. most of the tidal disruption events (tdes) and candidates discovered in the optical/uv have broad optical emission lines with complex and diverse profiles of puzzling origin. in this letter, w... | disc origin of broad optical emission lines of the tde candidate ptf09djl |
context. a low-mass companion to the two-solar mass star hip 65426 has recently been detected by sphere at around 100 au from its host. explaining the presence of super-jovian planets at large separations, as revealed by direct imaging, is currently an open question.aims: we want to derive statistical constraints on th... | exploring the formation by core accretion and the luminosity evolution of directly imaged planets. the case of hip 65426 b |
we use a state-of-the-art semi-analytic model to study the size and the specific angular momentum of galaxies. our model includes a specific treatment for the angular momentum exchange between different galactic components. disc scale radii are estimated from the angular momentum of the gaseous/stellar disc, while bulg... | structural and dynamical properties of galaxies in a hierarchical universe: sizes and specific angular momenta |
for the past few decades, there has been great interest in determining if even the most massive stars in our galaxy (namely the spectral o-type stars) are formed in a similar manner as the low- and intermediate-mass stars, that is, through the presence of accreting disks and powerful outflows. here, using sensitive obs... | an asymmetric keplerian disk surrounding the o-type protostar iras 16547-4247 |
exoplanets form in protoplanetary accretion discs. the total protoplanetary disc mass is the most fundamental parameter, since it sets the mass budget for planet formation. although observations with the atacama large millimeter/submillimeter array (alma) have dramatically increased our understanding of these discs, to... | constraining protoplanetary disc mass using the gi wiggle |
it seems surprising that the emissivity properties of the accretion disk ( à la page and thorne) surrounding the gibbons-maeda-garfinkle-horowitz-strominger (gmghs) black holes of heterotic string theory have not yet been studied. to fill this gap in the literature, we study the emissivity properties of the thin accret... | accretion disks around the gibbons-maeda-garfinkle-horowitz-strominger charged black holes |
we use the athena++ monte carlo (mc) radiation transfer module to post-process simulation snapshots from non-relativistic athena++ radiation magnetohydrodynamic (rmhd) simulations. these simulations were run using a gray (frequency integrated) approach but were also restarted and ran with a multi-group approach that ac... | spectral calculations of 3d rmhd simulations of super-eddington accretion onto a stellar-mass black hole |
we propose new analytic formulae describing light bending in the schwarzschild metric. for an emission radii above the photon orbit at the 1.5 schwarzschild radius, the formulae have an accuracy of better than 0.2% for the bending angle and 3% for the lensing factor for any trajectories that turn around a compact objec... | accurate analytic formula for light bending in schwarzschild metric |
magnetospheric accretion models predict that matter from protoplanetary disks accretes onto stars via funnel flows, which follow stellar magnetic field lines and shock on the stellar surfaces1-3, leaving hot spots with density gradients4-6. previous work has provided observational evidence of varying density in hot spo... | measuring the density structure of an accretion hot spot |
motivated by the non-linear star formation efficiency found in recent numerical simulations by a number of workers, we perform high-resolution adaptive mesh refinement simulations of star formation in self-gravitating turbulently driven gas. as we follow the collapse of this gas, we find that the character of the flow ... | collapse in self-gravitating turbulent fluids |
context. accretion at planetary-mass companions (pmcs) suggests the presence of a protoplanetary disc in the system, likely accompanied by a circumplanetary disc. high-resolution spectroscopy of accreting pmcs is very difficult due to their proximity to bright host stars. for well-separated companions, however, such sp... | resolved near-uv hydrogen emission lines at 40-myr super-jovian protoplanet delorme 1 (ab)b. indications of magnetospheric accretion |
we compile observations of high-frequency quasi-periodic oscillations (qpos) around black holes, both stellar and supermassive, and compare their positions in the parameter space of black hole mass, spin, and oscillation frequency. we find that supermassive black holes occupy a separate region of parameter space than s... | confrontation of observation and theory: high-frequency qpos in x-ray binaries, tidal disruption events, and active galactic nuclei |
black hole binary (bhb) systems comprise a stellar-mass black hole and a closely orbiting companion star. matter is transferred from the companion to the black hole, forming an accretion disk, corona and jet structures. the resulting release of gravitational energy leads to the emission of x-rays1. the radiation is aff... | accretion geometry of the black-hole binary cygnus x-1 from x-ray polarimetry |
we present a composite model and radiative transfer simulations of the massive star-forming core w33a mm1. the model was tailored to reproduce the complex features observed with atacama large millimeter/submillimeter array at ≈0.2 arcsec resolution in ch3cn and dust emission. the mm1 core is fragmented into six compact... | radiative transfer modelling of w33a mm1: 3d structure and dynamics of a complex massive star-forming region |
supermassive black hole (smbh) binaries form due to galaxy mergers and minor accretion events. when the smbhs are accreting, they form dual or binary agn and can give rise to double-peaked emission lines in the optical spectra of the merger remnant. the double-peaked emission lines could also be due to jet-ism interact... | searching for dual agn in galaxies with double-peaked emission line spectra using radio observations |
protoplanetary disks with non-axisymmetric structures have been observed. the rossby wave instability (rwi) is considered as one of the origins of the non-axisymmetric structures. we perform linear stability analyses of the rwi in barotropic flow using four representative types of the background flow on a wide paramete... | parametric study of the rossby wave instability in a two-dimensional barotropic disk |
whether the magnetorotational instability (mri) can amplify initially weak magnetic fields to dynamically relevant strengths in core-collapse supernovae is still a matter of active scientific debate. recent numerical studies have shown that the first phase of mri growth dominated by channel flows is terminated by paras... | on the maximum magnetic field amplification by the magnetorotational instability in core-collapse supernovae |
recent chime/frb observations of the periodic repeating fast radio bursts (frb) 180916b have produced a homogeneous sample of 44 bursts. these permit a redetermination of the modulation period and phase window, in agreement with earlier results. if the periodicity results from the precession of an accretion disc, in an... | precession and jitter in frb 180916b |
after protoplanets have acquired sufficient mass to open partial gaps in their natal protostellar disks, residual gas continues to diffuse onto horseshoe streamlines under the effect of viscous dissipation, and to meander in and out of the planets' hill sphere. within the hill sphere, the horseshoe streamlines intercep... | accretion of gas giants constrained by the tidal barrier |
we analyze the chemical properties of a set of solar vicinity stars, and show that the small dispersion in abundances of α-elements at all ages provides evidence that the star formation history (sfh) has been uniform throughout the thick disk. in the context of long-timescale infall models, we suggest that this result ... | clues to the formation of the milky way's thick disk |
we present single-dish 12co(1-0) and 12co(2-1) observations for 14 low-redshift quasi-stellar objects (qsos). in combination with optical integral field spectroscopy, we study how the cold gas content relates to the star formation rate (sfr) and black hole accretion rate. 12co(1-0) is detected in 8 of 14 targets and 12... | integral field spectroscopy of nearby quasi-stellar objects - ii. molecular gas content and conditions for star formation |
we perform a global 2.5d general-relativistic radiation magnetohydrodynamic simulation of supercritical accretion onto a neutron star with a 2 × 1010 g dipolar magnetic field, as a model of a neutron-star-powered ultraluminous x-ray source (ulx). we compute a lower limit on the total luminosity of ~2.5 ledd, and find t... | beamed emission from a neutron-star ulx in a grrmhd simulation |
we study the influence of the presence of a strong bar in disc galaxies which host an active galactic nucleus (agn). using data from the sloan digital sky survey and morphological classifications from the galaxy zoo 2 project, we create a volume-limited sample of 19 756 disc galaxies at 0.01 < z < 0.05 which have... | galaxy zoo: the effect of bar-driven fuelling on the presence of an active galactic nucleus in disc galaxies |
we calculate the ages, orbits and phase-space coordinates for a sample of ~4 million lamost and gaia stars. the ages are cross-matched and compared with values from two other popular age catalogs, which derive the ages using different methods. of these ~4 million stars, we select a sample of 1.3 million stars and inves... | the flattening metallicity gradient in the milky way's thin disk |
context. the picture of pre-main-sequence evolution is often simplified by the application of classical initial models. such models have large initial radii and sufficient uniform contraction to make them fully convective, however, real stars are born as small protostellar seeds in collapsing molecular clouds and obtai... | pulsational instability of pre-main-sequence models from accreting protostars. i. constraining the input physics for accretion with spectroscopic parameters and stellar pulsations |
liu and collaborators recently proposed an elliptical accretion disk model for tidal disruption events (tdes). they showed that the accretion disks of optical/uv tdes are large and highly eccentric and suggested that the broad optical emission lines with complex and diverse profiles originate in a cool eccentric accret... | measuring black hole masses from tidal disruption events and testing the mbh-σ* relation |
we present optical spectroscopy observations of 145 high-mass pre-main-sequence candidates from the catalog of vioque et al. 2020 from these, we provide evidence for the herbig nature of 128 sources. this increases the number of known objects of the class by ~50%. we determine the stellar parameters of these sources us... | identification and spectroscopic characterization of 128 new herbig stars |
the observed correlation between outer giant planets and inner super-earths is emerging as an important constraint on planet formation theories. in this study, we focus on kepler-167, which is currently the only system known to contain both inner transiting super-earths and a confirmed outer transiting gas giant compan... | kepler-167e as a probe of the formation histories of cold giants with inner super-earths |
the typical optical-uv continuum slopes observed in many type-1 active galactic nuclei (agns) are redder than expected from thin accretion disk (ad) models. a possible resolution to this conundrum is that many agns are reddened by dust along the line of sight. to explore this possibility, we stack 5000 sdss agns with l... | evidence that most type-1 agns are reddened by dust in the host ism |
aims: the formation scenario of extended counter-rotating stellar disks in galaxies is still debated. in this paper, we study the s0 galaxy ic 719 known to host two large-scale counter-rotating stellar disks in order to investigate their formation mechanism.methods: we exploit the large field of view and wavelength cov... | evidence for the formation of the young counter-rotating stellar disk from gas acquired by ic 719 |
we report the discovery of a giant stellar tidal stream in the halo of ngc 4631, a nearby edge-on spiral galaxy interacting with the spiral ngc 4656, in deep images taken with a 40 cm aperture robotic telescope. the stream has two components: a bridge-like feature extending between ngc 4631 and ngc 4656 (streamse) and ... | a stellar tidal stream around the whale galaxy, ngc 4631 |
according to our current cosmological model, galaxies like the milky way are expected to experience many mergers over their lifetimes. the most massive of the merging galaxies will be dragged towards the disc plane, depositing stars and dark matter into an accreted disc structure. in this work, we utilize the chemodyna... | the gaia-eso survey: a quiescent milky way with no significant dark/stellar accreted disc |
aims: we investigate the evolution of x-ray selected tidal disruption events.methods: new events are found in near real-time data from xmm-newton slews, and are monitored by multi-wavelength facilities.results: in august 2016, x-ray emission was detected from the galaxy xmmsl2 j144605.0+685735 (also known as 2masx 1446... | xmmsl2 j144605.0+685735: a slow tidal disruption event |
recently, the vertical shear instability (vsi) has become an attractive purely hydrodynamic candidate for the anomalous angular momentum transport required for weakly ionized accretion disks. in direct three-dimensional numerical simulations of vsi turbulence in disks, a meridional circulation pattern was observed that... | anisotropic hydrodynamic turbulence in accretion disks |
we present the discovery of a low-frequency ≈5.7 hz quasi-periodic oscillation (qpo) feature in observations of the black hole x-ray binary maxi j1535-571 in its soft-intermediate state, obtained in 2017 september-october by the neutron star interior composition explorer. the feature is relatively broad (compared to ot... | a nicer discovery of a low-frequency quasi-periodic oscillation in the soft-intermediate state of maxi j1535-571 |
only recently, complex models that include the global dynamics from dwarf satellite galaxies, dark matter halo structure, gas infalls, and stellar disk in a cosmological context became available to study the dynamics of disk galaxies such as the milky way (mw). we use a mw model from a high-resolution hydrodynamical co... | galactoseismology in cosmological simulations: vertical perturbations by dark matter, satellite galaxies and gas |
the largest observed supermassive black holes (smbhs) have a mass of {m}{{bh}}≃ {10}10 {\text{}}{m}⊙ , nearly independent of redshift, from the local (z≃ 0) to the early (z\gt 6) universe. we suggest that the growth of smbhs above a few × {10}10 {\text{}}{m}⊙is prevented by small-scale accretion physics, independent of... | is there a maximum mass for black holes in galactic nuclei? |
recent observational studies have uncovered a small number of very metal-poor (vmp) stars with cold kinematics in the galactic disc and bulge. however, their origins remain enigmatic. we select a total of 138 milky way (mw) analogues from the tng50 cosmological simulation based on their z = 0 properties: discy morpholo... | on the likelihoods of finding very metal-poor (and old) stars in the milky way's disc, bulge, and halo |
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