### Conveners

#### Afternoon session

- Hansjoerg Dittus ()

#### Afternoon session

- Claus Laemmerzahl (University of Bremen)

#### Afternoon session

- Mimoza Hafizi (University of Tirana)

Within General Relativity there are several schemes to define a time scale. One geometry based time scale is given by the Marzke Wheeler clock or the standard clock defined by Perlick. Further time scales are given by the rotation of the Earth or pulsars around their own axis and by the rotation of objects around central gravitating bodies. And, finally, the most stable clocks today ar atomic...

3 years after its launch from the Russian Baikonur Cosmodrome, all systems and instruments are working properly on the Spektr-RG (SRG) observatory. With eROSITA, the German contribution, half of all 8 sky surveys have been completed so far. Millions of X-ray sources, mostly of extragalactic nature, have been discovered. This confirmes what we had hoped for before the launch and had already...

Progress in our understanding of astrophysical transients has followed a series of fits and spurts, often moving forward in a random walk manner, sometimes moving forward, sometimes backward. In large part, this arises from the bandwagon nature of science, where contrary views are often stifled. In an era where deviations from the standard picture become increasingly difficult, Remo Ruffini...

I.F. Mirabel & L.F. Rodriguez

The existence of supermassive black holes (SMBHs) of ~10^9 solar masses in quasars at z ~7.5, when the Universe was ~700 Myr old, is an intriguing puzzle and their origin remains unconstraint. It have been proposed that those SMBHs result from rapidly growing BH seeds of stellar and/or intermediate masses BHs at redshifts z ~30. However, there is no consensus...

An increasing number of space activities for the precise measurement of gravitational fields by means of quantum sensors has been carried out during the last 20 years. Results proved the importance of those experiments and demonstrate the necessity of further technology developments in order to set up new approaches to spacetime geometry.

Recent and planned space missions and their results...

Relaxation mechanisms of collisionless self-gravitating systems of fermions in cosmology, can lead to spherical equilibrium states which are stable, long-lived, and able to explain the dark matter (DM) halos in galaxies. We show that the most general fermionic DM profile out of such a mechanism, develops a degenerate compact core which is surrounded by an extended halo. When applied to the...

It has become commonplace is astronomy to describe the transverse coarse structure of jets in loosely defined terms such as `sheath" and`

spine" based on discussions of parsec scale properties. But, the applicability, dimension and prominence of these features on sub-lt-yr scales has previously been unconstrained by observation. The first direct evidence of jet structure near the source in...

We study the Peccei-Quinn (PQ) symmetry of the sterile right-handed neutrino sector and the gauge

symmetries of the Standard Model. Due to four-fermion interactions, spontaneous breaking of these

symmetries at the electroweak scale generates top-quark Dirac mass and sterile-neutrino Majorana

mass. The top quark channels yield massive Higgs, $W^{\pm }$ and $Z^{0}$ bosons. The...

Selected magnetohydrodynamical processes around a Kerr black hole are analytically investigated adopting horizon penetrating coordinates and focusing in particular on the associated electrodynamics and energetics.

I will discuss the recent developments concerning the analytic determination of the scattering angle, including both the conservative and the radiative parts.

We investigate the structure and stability against radial oscillations, pycnonuclear reactions, and inverse beta-decay of hot white dwarfs. We find that the temperature produces important effects on the equilibrium and radial stability of white dwarfs. The stable equilibrium configuration results are compared with white dwarfs estimated from the Extreme Ultraviolet Explorer Survey and Sloan...

Currently operating and future planned missions need robust methods in determining the distances to GRBs. We purpose to provide a simple method for estimating distances to cosmological gamma-ray bursts. We construct $E_{\rm p, i}$-$E_{\rm iso}$ correlation for short gamma-ray bursts based on events with well established spectral peak energies. Applying minimal criteria, we sample SGRBs from...

We propose an alternative method to solve the problem of matching two solutions of Einstein equations along a matching surface. It is based upon the use of the eigenvalues of the Riemann curvature tensor, which are required to coincide along the matching surface. In addition, the extrema of the eigenvalues are used to determine the minimum radius of the matching surface, a procedure that...