A5024898806- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Mechanics and Biomechanics Studies
- Galaxies: Formation, Evolution, Phenomena
- High-pressure geophysics and materials
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Solar and Space Plasma Dynamics
- Heat Transfer Mechanisms
- Stellar, planetary, and galactic studies
- Calibration and Measurement Techniques
- Superconducting Materials and Applications
- Cosmology and Gravitation Theories
- Magnetic confinement fusion research
- Superconducting and THz Device Technology
- Laser-Plasma Interactions and Diagnostics
- Advanced X-ray Imaging Techniques
- Advanced X-ray and CT Imaging
- Experimental and Theoretical Physics Studies
Polish Academy of Sciences
2016-2025
Center for Theoretical Physics
2016-2025
Silesian University in Opava
2020
Czech Academy of Sciences, Institute of Physics
2020
University of Copenhagen
2020
Sapienza University of Rome
2015
Nicolaus Copernicus Astronomical Center
2001-2010
University of Nevada, Las Vegas
2006-2008
Campo Arqueologico de Mertola
2007
Princeton University
2005
The X-ray Integral Field Unit (X-IFU) is the high resolution spectrometer of ESA Athena observatory. Over a field view 5' equivalent diameter, it will deliver spectra from 0.2 to 12 keV with spectral 2.5 eV up 7 on ∼ 5" pixels. X-IFU based large format array super-conducting molybdenum-gold Transition Edge Sensors cooled at 90 mK, each coupled an absorber made gold and bismuth pitch 249 μm. A cryogenic anti-coincidence detector located underneath prime TES enables non background be reduced....
We associate the existence of short-lived compact radio sources with intermittent activity central engine caused by a radiation pressure instability within an accretion disk. Such objects may constitute numerous sub-class Giga-Hertz Peaked Spectrum sources, in accordance population studies radio-loud active galaxies, as well detailed investigations their morphologies. perform model computations assuming viscosity parametrization proportional to geometrical mean total and gas pressure. The...
The X-ray Integral Field Unit (X-IFU) on board the Advanced Telescope for High-ENergy Astrophysics (Athena) will provide spatially resolved high-resolution spectroscopy from 0.2 to 12 keV, with 5 arc second pixels over a field of view minute equivalent diameter and spectral resolution 2.5 eV up 7 keV. In this paper, we first review core scientific objectives Athena, driving main performance parameters X-IFU, namely resolution, view, effective area, count rate capabilities, instrumental...
Some of the accreting black holes exhibit much stronger variability patterns than usual stochastic variations. Radiation pressure instability is one proposed mechanisms which could account for this effect. We aim to model luminosity changes objects with hole mass 10, 10$^5$, and 10$^7$ solar masses, using time-dependent evolution an accretion disk unstable due dominant radiation pressure. use a 1-dimensional, vertically integrated numerical scheme models simultaneous corona, coupled by...
Quasi-periodic eruptions (QPEs) are luminous bursts of soft X-rays from the nuclei galaxies, repeating on timescales hours to weeks
Abstract An accretion disk formed around a supermassive black hole after it disrupts star is expected to be initially misaligned with respect the equatorial plane of hole. This misalignment induces relativistic torques (the Lense–Thirring effect) on disk, causing precess at early times, whereas late times aligns and precession terminates 1,2 . Here we report, using high-cadence X-ray monitoring observations tidal disruption event (TDE), discovery strong, quasi-periodic flux temperature...
Quasi-periodic Eruptions (QPEs) represent a novel class of extragalactic X-ray transients that are known to repeat at roughly regular intervals few hours days. Their underlying physical mechanism is topic heated debate, with most models proposing they originate either from instabilities within the inner accretion flow or orbiting objects. At present, our knowledge how QPEs evolve over an extended timescale multiple years limited, except for unique QPE source GSN 069. In this study, we...
Abstract We perform a detailed study of the black hole spin Cyg X-1, using accurate broadband X-ray data obtained in soft spectral state by simultaneous NICER and NuSTAR observations, supplemented at high energies INTEGRAL data. use relativistic disk model kerrbb together with different models Comptonization high-energy tail relativistically broadened reflection features. Unlike most previous studies, we tie parameters broadening models, thus combining continuum methods determination. also...
The time-dependent evolution of the accretion disk around black hole is computed. classical description α-viscosity adopted so driven by instability operating in innermost radiation pressure-dominated part disk. We assume that optically thick always extends down to marginally stable orbit, it never evacuated completely. include effect advection, coronal dissipation, and vertical outflow. show presence corona and/or outflow reduces amplitude outburst. If only about half energy dissipated...
We investigate the properties and evolution of accretion tori formed after coalescence two compact objects. At these extreme densities temperatures, accreting torus is cooled mainly by neutrino emission produced primarily electron positron capture on nucleons (β-reactions). solve for disk structure its time introducing a detailed treatment equation state which includes photodisintegration helium, condition β-equilibrium, opacities. self-consistently calculate chemical equilibrium in gas...
We discuss two important instability mechanisms that may lead to the limit-cycle oscillations of luminosity accretion disks around compact objects: ionization and radiation-pressure instability. Ionization is well established as a mechanism X-ray novae eruptions in black hole binary systems but its applicability AGN still problematic. Radiation pressure theory has very weak observational background any these sources. In present paper we attempt confront parameter space instabilities with...
Magnetically arrested accretion flows are thought to fuel some of the supermassive black holes and power their relativistic jets. We calculate study a time sequence linear circular polarimetric images numerical, high resolution long duration simulations magnetically dominated investigate observational signatures strong magnetic fields near event horizon non-rotating hole. find that magnitude resolved polarizations is rather sensitive assumption coupling electron ions in flow. Models with...
Rapid, hyper-Eddington accretion is likely to power the central engines of gamma-ray bursts (GRBs). In extreme conditions densities and temperatures accreting torus cooled by neutrino emission rather than radiation. Another important cooling mechanism advection energy into black hole. We compute time evolution a neutrino-dominated disc that proceeds during burst investigate changes in its density temperature. The discrimination between short long made on basis different rates material inflow...
We calculate the structure and short-term evolution of a gamma-ray burst (GRB) central engine in form turbulent torus accreting onto stellar mass black hole. Our models apply to short GRB events, which remnant forms after neutron star–black hole or double star merger is subsequently accreted. study two-dimensional, relativistic concentrate on effects flow parameters as well neutrino cooling. compare resulting emission results our previous one-dimensional simulations. find that cooled...
ABSTRACT Short gamma-ray bursts (GRBs) are known to be associated with binary neutron star (NSNS) or black hole–neutron (BHNS) mergers. The detection of gravitational waves and its electromagnetic counterpart GW/GRB 170817A has shown that interactions between relativistic jets mildly ejecta influence observed radiation. Previous studies simulated a uniform jet propagating through homologously expanding wind; however, disc outflows launched together during accretion, making the interaction...
We observed 17 optically-selected, radio-quiet high-redshift quasars with the Chandra Observatory ACIS, and detected 16 of them. The have redshift between 3.70 6.28 include highest known. When compared to low-redshift ROSAT, these high are significantly more X-ray quiet. also find that spectral index objects is flatter than average at lower redshift. These trends confirm predictions models where accretion flow described by a cold, optically-thick disk surrounded hot, optically thin corona,...
We derive the conditions for shock formation in a quasi-spherical, slightly rotating flows. verify results of semi-analytical, stationary calculations with time evolution studied by numerical hydrosimulations, and we study oscillations position. also behaviour flows varying specific angular momentum, where ‘hysteresis’ type loop is found when passing through multiple sonic points region. Our are agreement time-scales shapes luminosity flares observed Sgr A*. These models may be applicable...
We perform 1D/2D/3D relativistic hydrodynamical simulations of accretion flows with low angular momentum, filling the gap between spherically symmetric Bondi and disc-like flows. Scenarios different directional distributions momentum falling matter varying values key parameters such as spin central black hole, energy are considered. In some scenarios shock front is formed. identify ranges for which after formation moves towards or outwards hole long lasting oscillating observed. The...
Physical mechanism responsible for high viscosity in accretion disks is still under debate. Parameterization of the viscous stress as $αP$ proved to be a successful representation this outer parts disk, explaining dwarf novae and X-ray outbursts due ionization instability. We show that parameterization can also adopted innermost part disk where adoption $α$-viscosity law implies presence instability radiation pressure dominated region. study time evolution such disks. time-dependent behavior...
We consider effects of MHD turbulence on viscosity during the evolution thermal-viscous ionization instability in standard α-accretion disks. possibility that accretion onto a supermassive black hole proceeds through an outer disk and inner radiatively inefficient advection-dominated flow. In this scenario we follow time disk, which parameter α is constant throughout whole cycle, as implied by strength turbulence. conclude hydrogen promising mechanism to explain intermittent activity AGNs.
We consider the gamma ray burst (GRB) central engine that is powered by collapse of a massive rotating star or compact binary merger. The hot and dense accretion disk, which composed free nucleons, electron-positron pairs, helium, cooled neutrino emission. A significant number density neutrons in inner disk body provide conditions for neutron rich plasma GRB outflows jets. Helium synthesized if rate large, heavy nuclei are also formed outer at distances above 150-250 $r_{g}$ from black hole....
Aims. During the bright outburst in 2011, black hole candidate IGR J17091-3624 exhibited strong quasi-periodic flare-like events (on timescales of tens seconds) some characteristic states, so-called heartbeat state. From theoretical point view, these oscillations may be modeled by process accretion disk instability, driven dominant radiation pressure and enhanced heating plasma. Although mean rate this source is probably below Eddington limit, will still have large amplitudes. As...