The many tones of accretion - to the memory of Tomaso Belloni

Session

Timing (Belloni Session). Session: Variability & Lags

8 Sept 2026, 15:15

Cefalù

42. The accretion flow in black hole X-ray binaries through the “lens” of X-ray spectral-timing

Barbara De Marco (Universitat Politècnica de Catalunya)

08/09/2026, 15:15

Talk

Black hole X-ray binaries (BHXRBs) provide an exceptional laboratory for studying the physics of accretion under strong gravity. In particular, energy-dependent variability and X-ray time lags carry key information about the geometry, dynamics, and evolution of the accretion flow. In this talk, I will review the current state-of-the-art in spectral-timing studies of BHXRBs, focusing on how...

105. Evidence for the different timing behaviours of radio-loud and radio-quiet XRBs

Zuobin Zhang (University of Oxford)

08/09/2026, 16:30

Talk

Accreting stellar-mass black holes are known to populate two distinct tracks in the radio:X-ray luminosity plane, commonly referred to as the radio-loud and radio-quiet branches. Despite nearly four decades of observational and theoretical efforts, the physical origin of this dichotomy remains poorly understood. We have carried out a systematic study of the X-ray timing properties of a large...

58. Evolution in concert: Spectral-timing correlation of variability components in Cyg X-1

Seth Larner (Washington University, St. Louis MO, USA)

08/09/2026, 16:45

Talk

The black hole X-ray binary Cygnus X-1 exhibits high levels of variability spanning many decades in frequency across all of its spectral states. This broad band variability power is comprised of several distinct components evolving in concert as the source changes states. The amplitudes, frequencies, and energy dependent lags of these components reveal information about the physical accretion...

86. Neutron star mass and equation of state determined from precession models of quasi-periodic oscillations

Gabriel Török (Silesian University in Opava)

08/09/2026, 17:00

Poster

Quasi-periodic oscillations (QPOs) in the X-ray variability of accreting neutron stars provide key insights into accretion in strong gravity and the equation of state of dense matter (EoS). We discuss the possible precession origin of twin-peak QPOs, focusing particularly on two specific models. The first is the relativistic precession model, which links QPO frequencies to the frequencies of...

9. Why is our community allergic to timelags being produced by Comptonization?

Nick Kylafis (Institute of Astrophysics, FORTH, Crete)

Talk

It is well accepted by our community that the hard X-ray spectra in black-hole X-ray binaries (BHXRBs) are produced by Comptonization of soft photons. It is also well known that Comptonization produces timelags. This is because the more the soft photons are scattered, the more their energy is increased, the larger the random walk that they do in the scattering medium, and the larger their...