A5046122424- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Mechanics and Biomechanics Studies
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Relativity and Gravitational Theory
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
- History and Developments in Astronomy
- Black Holes and Theoretical Physics
- Particle Accelerators and Free-Electron Lasers
- Scientific Measurement and Uncertainty Evaluation
- Advanced X-ray Imaging Techniques
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Laser-Plasma Interactions and Diagnostics
- Phase Equilibria and Thermodynamics
Institut d'Astrophysique de Paris
2015-2024
Polish Academy of Sciences
2015-2024
Nicolaus Copernicus Astronomical Center
2015-2024
Sorbonne Université
2014-2023
Centre National de la Recherche Scientifique
2014-2023
Institute of Astronomy
2002-2021
Institute of Applied Astronomy
2021
Russian Academy of Sciences
2005-2020
Kavli Institute for Particle Astrophysics and Cosmology
2017-2018
University of California, Santa Barbara
2000-2018
view Abstract Citations (1386) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Slim Accretion Disks Abramowicz, M. A. ; Czerny, B. Lasota, J. P. Szuszkiewicz, E. A new branch of equilibrium solutions for stationary accretion disks around black holes is found. These correspond to moderately super-Eddington rates. The existence the a consequence an additional cooling due general relativistic Roche lobe overflow and horizontal advection heat. On...
view Abstract Citations (684) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Thermal Equilibria of Accretion Disks Abramowicz, Marek A. ; Chen, Xingming Kato, Shoji Lasota, Jean-Pierre Regev, Oded We show that most hot, optically thin accretion disk models which ignore advective cooling are not self-consistent. have found new types solutions where is dominated by radial advection heat. These thermally and viscously stable. Publication: The...
We investigate how the total radio luminosity of AGN-powered sources depends on their accretion and central black hole mass. Our studies cover about 7 orders magnitude in (expressed Eddington units, i.e., as ratios) full range AGN masses. find that AGNs form two distinct well-separated sequences radio-loudness-Eddington-ratio plane. The "upper" sequence is formed by radio-selected AGNs, "lower" contains mainly optically selected objects. Whereas an apparent "gap" between may be artifact...
view Abstract Citations (502) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Steps toward Determination of the Size and Structure Broad-Line Region in Active Galactic Nuclei. I. an 8 Month Campaign Monitoring NGC 5548 with IUE Clavel, J. ; Reichert, G. A. Alloin, D. Crenshaw, M. Kriss, Krolik, H. Malkan, Netzer, Peterson, B. Wamsteker, W. Altamore, Baribaud, T. Barr, P. Beck, S. Binette, L. Bromage, E. Brosch, N. Diaz, Filippenko, V. Fricke,...
All ten LIGO/Virgo binary black hole (BH-BH) coalescences reported following the O1/O2 runs have near-zero effective spins. There are only three potential explanations for this. If BH spin magnitudes large, then: (i) either both vectors must be nearly in orbital plane or (ii) angular momenta of BHs oppositely directed and similar magnitude. Then there is also possibility that (iii) small. We consider third hypothesis within framework classical isolated evolution scenario BH-BH merger...
The study of ultraluminous X-ray sources (ULXs) has changed dramatically over the last decade. In this review we first describe most important observations ULXs in various wavebands, and across multiple scales space time. We discuss recent progress current unanswered questions. consider range theories ULX properties light observational progress. Applying these models to neutron-star offers particularly stringent tests, as is unique case where mass accretor effectively fixed.
We calculate self-consistent models of X-ray-irradiated accretion discs in close binary systems. show that a point X-ray source powered by and located the disc plane cannot modify structure, mainly because self-screening its outer regions. As observations emission regions low-mass binaries is dominated reprocessed flux, these systems must be either warped or irradiated above plane, both. analyse thermal--viscous stability derive criteria such find that, contrary to usual assumptions,...
We model the population of AM CVn systems in Galaxy and discuss detectability these with optical, X-ray gravitational-wave detectors. concentrate on short-period (P < 1500 s) systems, some which are expected to be a phase direct-impact accretion. Using self-consistent for star-formation history radial distribution stars plus simple models emission optical radiation from interstellar absorption, we derive sample that can detected and/or bands. At shortest periods, detectable all sources,...
Recently, several ways of verifying the existence black-hole horizons have been proposed. We show here that most these suggestions are irrelevant to problem horizon, at best they can rule out presence conventional baryonic matter in outer layers candidates. More generally, we argue it is fundamentally impossible detect electromagnetic radiation direct evidence for a horizon. This applies also future observations, which would trace very accurately details space-time metric body suspected...
We study the prospect of explaining outbursts Soft X-ray Transients (SXTs) by thermal-viscous instability in a thin disc. This is linked to hydrogen ionization and significantly changed when irradiation disc X-rays from inner regions included. present first numerically reliable, physically consistent calculations outburst cycles which include effects accretion irradiation. The decay governed irradiation, as pointed out King & Ritter (1998), leading slow exponential decays. At end outburst,...
We consider the X-ray luminosity difference between neutron star and black hole soft transients (NS BH SXTs) in quiescence. The current observational data suggest that SXTs are significantly fainter than NS SXTs. luminosities of quiescent consistent with predictions binary-evolution models for mass transfer rate if (1) accretion occurs via an advection-dominated flow (ADAF) these systems (2) accreting compact objects have event horizons. not ADAF when combined models, unless most accreted is...
We investigate the conjecture by Sikora, Stawarz, and Lasota that observed active galactic nuclei (AGNs) radio loudness bimodality can be explained morphology-related of black hole spin distribution in centers galaxies: central holes (BHs) giant elliptical galaxies may have (on average) much larger spins than spiral/disk galaxies. study how accretion from a warped disk influences evolution conclude within cosmological framework, where most massive BHs grown mass via merger-driven accretion,...
Massive black holes (MBHs), in contrast to stellar mass holes, are expected substantially change their properties over lifetime. MBH masses increase by several orders of magnitude a Hubble time, as illustrated Sołtan's argument. spins also must evolve through the series accretion and mergers events that MBHs. We present simple model traces joint evolution across cosmic time. Our includes MBH–MBH mergers, merger-driven gas accretion, stochastic fueling MBHs molecular cloud capture, basic...
We report on a scheme for incorporating vertical radiative energy transport into fully relativistic, Kerr-metric model of optically thick, advective, transonic alpha disks. Our code couples the radial and equations accretion disk. The flux was computed in diffusion approximation, convection is included mixing-length approximation. present detailed structure this "two-dimensional" slim-disk alpha=0.01. then calculated emergent spectra integrated over disk surface. values surface density,...
The behaviour of carbon-oxygen white dwarfs (WDs) subject to direct helium accretion is extensively studied. We aim analyze the thermal response accreting WD mass deposition at different time scales. analysis has been performed for initial WDs masses and rates in range (0.60 - 1.02) Msun 1.e-9 1.e-5 Msun/yr, respectively. Thermal regimes parameters space M_{WD} dot{M}_{He}, leading formation red-giant-like structure, steady burning He, mild, strong dynamical flashes have identified...
Abstract We consider ultraluminous X–ray systems (ULXs) where the accretor is a neutron star rather than black hole. show that recently discovered example (M82 X–2) fits naturally into simple picture of ULXs as beamed sources fed at super-Eddington rates, provided its magnetic field weaker (≃1011G) new-born X-ray pulsar, expected if there has been mass gain. Continuing accretion likely to weaken point pulsing stops, and make system indistinguishable from ULX containing Accordingly we suggest...
Abstract We consider the three currently known pulsing ultraluminous X-ray sources (PULXs). show that in one of them observed spin-up rate requires super-Eddington accretion rates at magnetospheric radius, even if magnetar-strength fields are assumed. In two other systems, a normal-strength neutron star field implies magnetosphere. Adopting mass transfer as defining characteristic ULX we find parameters required for self-consistent simultaneous fits luminosities and pulsed systems. These...
Context. The Event Horizon Telescope (EHT) collaboration recently obtained first images of the surroundings supermassive compact object M87* at center galaxy M87. Aims. We want to develop a simple analytic disk model for accretion flow M87*. Compared general-relativistic magnetohydrodynamic (GRMHD) models, it has advantage being independent turbulent character flow, and controlled by only few easy-to-interpret, physically meaningful parameters. use this predict image assuming that is either...
The LIGO/Virgo gravitational--wave observatories have detected 50 BH-BH coalescences. This sample is large enough to allowed several recent studies draw conclusions about the branching ratios between isolated binaries versus dense stellar clusters as origin of double BHs. It has also led exciting suggestion that population highly likely contain primordial black holes. Here we demonstrate such cannot yet be robust, because current uncertainties in key aspects binary evolution. These include...
We have developed 1D time-dependent numerical models of accretion discs, using an adaptive grid technique and implicit scheme, in which the disc size is allowed to vary with time. The code fully resolves cooling heating fronts propagating disc. show that radius outer edge fixed produce incorrect results, from probably conclusions about viscosity law been inferred. In particular we outside-in outbursts are possible when a standard bimodal behaviour Shakura–Sunyaev parameter α used. also...
We derive all relevant equations needed for constructing a global general relativistic model of advectively cooled, very hot, optically thin accretion disks around black holes and present solutions that describe advection-dominated flows in the gravitational field Kerr hole.