Nooshin Torabi
Department of Physics, Sharif University of Technology
Gravitational Lensing of Gravitational Waves as a probe to study the distribution of matter in the Cosmos
Supervisor: Shant Baghram and Sohrab Rahvar
Abstract: In this research, Our goal was to investigate the gravitational lensing (GL) of gravitational waves (GW), particularly focusing on the impact of primordial black holes on the number of lensed gravitational wave events. In the case of strong lensing, two or more images of a single event can form, arriving at the observer with a time delay. The cross-section of strong lensing depends on the density distribution of the lens and its Einstein radius. Moreover, we will discuss the wave and geometric optics in context of GL of Gws. Strong lensing statistics includes calculating the number of lensed events and the distribution of time delays created between different images of a single event. This strongly depends on the assumed distribution of the lenses. In this work, we have considered the Navarro-Frenk-White (NFW) profile for dark matter halos and calculated the lensing optical depth and found that it is approximately four orders of magnitude smaller than when the lens is considered as a point mass. Furthermore, the mass range of halos effective in strong lensing is found to be approximately 1013 < M/M⊙ < 1015 , though this range also depends on the redshift of the source and lens. The existence of primordial black holes (PBH), which are candidates for dark matter, has long been a subject of debate in the scientific community. In this study, by considering PBHs as sources of GWs due to their mergers alongside astrophysical black hole mergers, and also their contribution to lensing as point-mass lenses, we calculated their impact on the number of lensed events. This number depends on the fraction of PBHs to dark matter and the assumed mass of them. The existence
یکشنبه 18 شهریور 1403، ساعت 14:00
Sunday 8 September – 14:00 Tehran Time
دانشکده فیزیک – طبقه پنجم – کلاس 512 Physics Department fifth floor – Room 512 /