Semináře

Přednášející: Odele Straub
Datum a čas: 16.6. 2022, 13:00

Dark Matter Searches Through Multi-Messenger Observations of Compact Stars

Přednášející: David Alvarez Castilo
Datum a čas: 9.6. 2022, 13:00

Early results from GRBAlpha and VZLUSAT-2 CubeSats with gamma-ray burst detectors

Přednášející: J. Řípa
Datum a čas: 26.5. 2022, 13:00

Images and photon ring signatures of thick disks surrounding black holes

Přednášející: Frederic Vincent
Datum a čas: 19.5. 2022, 13:00

Variability in discs around black holes: Broadband variability and QPOs

Přednášející: D. Bollimpalli
Datum a čas: 12.5. 2022, 13:00
Popis: Long-term observations have shown that black hole X-ray binaries exhibit strong, aperiodic variability on time scales of a few milliseconds to seconds. In addition, these systems also exhibit rapid variability in their X-ray light curves termed quasi-periodic oscillations (QPOs); also broadly classified into high-frequency and low-frequency QPOs. Understanding the nature of these variabilities and the underlying physical processes helps us probe the nature of the compact object and its surroundings. In this talk, I shall give a broad overview of the existing theoretical models for broadband variability and different types of QPOs, with a focus on the findings from the current state-of-art simulations of accretion discs in reproducing such time variability phenomena. In particular, I will discuss how the mass accretion rate fluctuations generated by the turbulence in the simulations naturally explain the observed broad-band variability in BHXRBs, and how the precession frequency of the inner geometrically thick disc differs from the standard Lense-Thirring precession frequency in truncated disc geometry and its implications to Type-C QPOs.

WKB formula for calculation quasinormal modes and grey-body factors: recipes for quick and accurate calculations

Přednášející: A. Zinhailo
Datum a čas: 29.4. 2022, 10:00

The generalized Lemaitre-Tolman-Bondi solution with nonzero pressure in modelling of cosmological black holes

Přednášející: E. Kopteva
Datum a čas: 21.4. 2022, 13:00

Exploring the Hot and Energetic Universe with Large and Small Satellites

Přednášející: Norbert Werner
Datum a čas: 24.2. 2022, 13:00