Relativistic Fluids around Compact Objects

Session

:special

5 May 2025, 09:30

Auditorium (Institute of Physics)

Conveners

:special: CAMK colloquium

• Krzysztof Nalewajko (Nicolaus Copernicus Astronomical Center, PAS, Warsaw, Poland)

:special: CFT special seminar

• Agnieszka Janiuk

:special: Welcome

• There are no conveners in this block

:special: reception, posters

• There are no conveners in this block

:special: Summary

• There are no conveners in this block

57. Cosmic Engines: How Black Holes Power the Brightest Objects in the Universe

Omer Bromberg (Tel Aviv University)

07/05/2025, 11:15

Review talk

Black-holes are like the genie of the lamp, as they can store vast amounts of energy within an extremely compact region. Under the right conditions, this energy can be harnessed to power some of the most luminous and energetic phenomena in the universe, like quasars and gamma-ray bursts. Current theoretical understanding suggests that the energy release is facilitated by the black-hole’s...

55. Today's Discoveries, Tomorrow's Frontiers: Multi-Messenger Astrophysics

Ore Gottlieb (CCA, Flatiron Institute)

08/05/2025, 12:00

Gamma-ray bursts

Review talk

Multi-messenger events involving gravitational waves (GWs) offer an unparalleled view into some of astrophysics' most profound mysteries. To date, detections have been limited to mergers of neutron stars and black holes - the powerhouses behind the universe's brightest emission: short-duration gamma-ray bursts (GRBs). However, recent observations of long GRBs accompanied by kilonovae have...

33. Comparison of solutions with different pseudo-Newtonian potentials in numerical simulations of accretion disk around compact objects

Maria Koper (University of Warsaw)

Black holes

Poster

I present hydrodynamic simulations of a thin accretion disk around compact objects using three different pseudo-Newtonian potentials: the Paczyński–Wiita and Kluźniak–Lee for a Schwarzschild black hole, and the newly devised potential for a Reissner–Nordström (RN) naked singularity. I study the differences between the properties of disks surrounding Schwarzschild black holes in two related...

13. Dynamics of relativistic jet formation: case study of GRB 090510

Agnieszka Janiuk

Gamma-ray bursts

Poster

We employ General Relativistic Magnetohydrodynamic (GRMHD)
simulations to investigate the properties of GRB 090510, a short gamma-ray
burst detected by Fermi-LAT. This study aims to quantify key parameters
such as jet opening angles, energetics, Lorentz factors, and jet structures,
alongside the progenitor details of the compact binary. Additionally, we
perform a suite of models to study...

48. Numerical studies of relativistic jets from black holes

Krzysztof Nalewajko (Nicolaus Copernicus Astronomical Center, PAS, Warsaw, Poland)

Relativistic jets

Poster

Relativistic jets are powerful collimated outflows from accreting compact objects, especially spinning black holes. Jets, as well as their associated mechanisms of energy dissipation and particle acceleration, can be investigated by global or local numerical simulations using methods like general-relativistic magneto-hydro-dynamics (GRMHD), particle-in-cell (PIC), etc. This presentation...

58. Outflowing fluxes in Radiative simulations of Ultra luminous X-ray sources

Angelos Karakonstantakis

Numerical simulations

Poster

Accretion flows that transfer gas at rates exceeding the Eddington limit
are optically thick but exhibit lower radiative efficiency compared to
thin discs. In this study, we present Radiative General Relativistic
Magnetohydrodynamic (GRRMHD) simulations of (intermediate)
super-Eddington accretion onto a black hole with a mass of 10 solar
masses, modeling ultra-luminous X-ray sources. Our...

54. Polarisation due to returning thermal disk radiation in the soft state of black-hole binaries

Aishee Chakraborty (University of Lodz)

Radiation

Poster

Reflection of thermal disk emission returning to the disk has recently been claimed to be important in the soft states of black hole binaries. In particular, Steiner et al. (2024) proposed that it could explain the X-ray polarisation measured by IXPE in the soft state of Cyg X-1. This would be an important argument for rapid rotation of black holes in HMXBs, since the effect is only important...

53. Probing Radiation Pressure Instabilities in Neutron star LMXBs

Pulkit Ojha (Centrum Fizyki Teoretycznej PAN)

Accretion

Poster

X-ray binaries hosting compact objects exhibit various variabilities in their X-ray spectra, often attributed to thermoviscous instabilities within their accretion disks. In particular, short-term variabilities , believed to arise from radiation pressure instabilities (RPIs) from the inner regions of the disk, have been well studied in black hole (BH) X-ray binaries. Recent observations...