The Sixth Zeldovich meeting

Session

Black holes and Penrose process

16 Jul 2026, 09:00

ICRANet, Pescara, Italy

34. Black Hole─Halo Mass Relation from UNIONS Weak Lensing

Wentao Luo (USTC)

16/07/2026, 09:00

Invited talk

This work presents, for the first time, direct constraints on the black hole─halo mass relation using weak gravitational-lensing measurements. We construct type I and type II active galactic nucleus (AGN) samples from the Sloan Digital Sky Survey, with a mean redshift of 0.4 (0.1) for type I (type II) AGNs. This sample is cross correlated with weak-lensing shear from the Ultraviolet Near...

27. Black hole irreducible mass increase by particle accretion

Shurui Zhang (ICRANet)

16/07/2026, 09:35

Invited talk

We report on the increase in irreducible mass resulting from a particle’s plunge along the inner most stable circular orbit (ISCO) into a black hole (BH), examining both cases: the conservative approximation and with gravitational wave (GW) radiation; the former corresponds to BH accretion, and the latter to extreme mass-ratio inspirals (EMRIs). For prograde orbits, we find that the ratio of...

57. Energy extraction from rotating black holes: electromagnetic and radiative Penrose processes

Arman Tursunov (Silesian University in Opava and Max Planck Institute for Radio Astronomy)

16/07/2026, 10:10

Invited talk

Rotating black holes provide a unique environment for extracting energy from spacetime rotation through processes occurring inside the ergosphere. In this presentation, I will review the classical Penrose mechanism and its electromagnetic extensions, with particular focus on the electric and magnetic Penrose processes. These mechanisms allow charged particles to gain energy through...

64. Near-horizon Polarization as a Diagnostic of Black Hole Spacetime

Bin Chen (Ningbo University)

16/07/2026, 11:15

Invited talk

A key challenge in imaging supermassive black holes is disentangling gravitational effects from plasma physics in order to accurately determine spacetime properties, particularly black hole spin. In our recent work, we present a fully covariant and rigorous analysis of the synchrotron emission from accreting plasma in the equatorial plane in the stationary, axisymmetric, high-conductivity...

38. Black holes in alternative theories of gravity

Jutta Kunz (University of Oldenburg)

16/07/2026, 11:50

Invited talk

Black holes, with their strong gravitational fields, provide an important testing ground for theories of gravity beyond General Relativity. Among the many proposed alternatives, considerable recent work has focused on scalar-tensor theories in which a scalar field couples to higher-curvature terms. The black hole solutions that arise in such theories can differ significantly from the...

54. Influence of a warm plasma on gravitational lensing by black holes

Volker Perlick

16/07/2026, 12:25

Invited talk

Analytical calculations of gravitational lensing by black holes and other compact or ultracompact objects, in particular of the shadow, were originally always done under the assumption that light rays are lightlike geodesics of the spacetime metric, i.e., that effects of a medium can be neglected. More recently the effect of a plasma was taken into account in numerous papers, where the plasma...