Seminars

"Nancy Grace Roman Space Telescope"

Radek Poleski (OAUW)

The Nancy Grace Roman Space Telescope is a flagship NASA mission with a 2.5 m primary mirror. Roman has only a single primary instrument: an infrared camera with a field of view of 0.28 deg^2, i.e., 100 times larger than the Hubble Space Telescope. Hence, Roman is perfectly suited to conduct large-scale surveys. There are three main surveys planned: weak lensing, supernovae, and microlensing exoplanets. I will present the current status and future plans of the mission. I'll also show how Roman planning was influenced by the results of the OGLE project.

"Distinguishing black holes from naked singularities via Tidal Disruption events"

Gabriel Tyszka (NCAC, Warsaw)

Tidal disruption events (TDEs) occur when a compact object tears apart a star with its tidal forces. In the standard interpretation of observed TDEs, the disrupting object is assumed to be a black hole. However, the cosmic censorship conjecture remains unproven, and TDEs probe the strong-field regime close to the central object, making them a potentially useful test of alternatives such as naked singularities. In this talk, we investigate whether a naked singularity described by the Reissner-Nordström metric with Q > M can be distinguished from a black hole through observations of TDEs. We perform smoothed particle hydrodynamics (SPH) simulations of the disruption of a Sun-like star using the PHANTOM code, and compare the dynamics of the debris in both cases. We then use ray tracing to compute bolometric light curves and search for differences that could serve as observational signatures of a naked singularity. We discuss the preliminary results and their implications for testing cosmic censorship with TDEs.

Presenting his work