XV Black Holes Workshop

Session

Session 6

20 Dec 2022, 11:00

ISCTE - University Institute of Lisbon

131. G. L. Cardoso: Holographic aspects of four-dimensional asymptotically flat N = 2 black holes

20/12/2022, 11:00

We explore holographic attributes of four-dimensional near-extremal Reissner-Nordstrom black hole solutions in ungauged N = 2 supergravity theories at the two-derivative level by recasting them as a specific first-order deformation in solution space, associated with an infinitesimal Harrison transformation, of black holes in an AdS2 space-time. We further show that the nAdS2 attractor...

132. S. Barsanti: Detecting massive scalar fields with Extreme Mass-Ratio Inspirals and LISA

20/12/2022, 11:15

Extreme Mass Ratio Inspirals (EMRIs), binary systems with a secondary stellar mass compact object inspiralling into a massive black hole, are among the main targets for LISA, as they harbour the potential for precise strong gravity tests. Although the description of these systems in modified theories of gravity can be dramatically complex, for a vast class of theories with additional scalar...

133. B. Juraev: Acceleration and radiation of cosmic rays nearby astrophysical black holes

20/12/2022, 11:30

In many astrophysical scenarios, the charge of the black hole is often neglected due to unrealistically large values of the charge required for the Reissner-Nordstrom spacetime metric. Black holes, however, might have a small electric charge because of various methods for selective accretion. We study how an imaginary small electric charge on a Schwarzschild black hole affects the ionization...

134. M. Boskovic: Probing scalar particles and forces with compact objects

20/12/2022, 11:45

In the highly relativistic regime around compact objects signatures of new physics may be unraveled. Some compact objects may in fact be constructed from beyond Standard Model matter. In particular, boson stars are useful toy models for exotic compact objects that could be produced in the Early Universe. Gravitational wave astronomy may also uncover a signature of a new force-mediating boson...

135. T. Ledvinka: Universality of curvature invariants in critical collapse of axisymmetric gravitational waves

20/12/2022, 12:00

Using the standard methods of numerical relativity we study axisymmetric gravitational waves undergo- ing gravitational collapse. Because it is known that the 1+log lapse choice breaks down in this situation, we propose a computationally effective alternative to maximal slicing and show that it allows the simulation to proceed until either the gravitational waves disperse or an apparent...

136. M. Lenzi: Black hole greybody factors from Korteweg-de Vries integrals

20/12/2022, 12:15

Perturbation theory of vacuum spherically symmetric spacetimes is a crucial tool for understanding the dynamics of black hole (BH) perturbations as well as BH scattering phenomena. Since the pioneering work of Regge and Wheeler it is known that the equations for the perturbations can be decoupled in terms of (gauge-invariant) master functions that satisfy 1 + 1 wave equations. However, while...

137. U. Sperhake: The Stochastic background from core collapse supernovae in massive scalar-tensor gravity

20/12/2022, 12:30

In this talk, we model the gravitational collapse of stars in massive scalar-tensor gravity. In this theory, the two tensorial gravitational-wave polarization modes are complemented by a massive breathing mode. This latter mode is triggered by the spontaneous scalarization mechanism discovered by Damour and Esposito-Farese; its radiation exhibits a drastically different behaviour dominated by...