A Tour from PBHs, GWs, Small Scales and Primordial non-Gaussianity and to AGN Jets and Ultralight Bosons

In the first part of the talk, I will discuss PBH formation, accompanying density induced GWs and probing small scales of inflation. Also I will discuss stellar mass, asteroid mass and super massive BH mass range and their possible interesting implications for cosmology. I will also discuss how we can probe PBHs conclusively via multi messengers (pulsar-time arrays and CMB distortions). In the second part, I will discuss the Fundamental Plane of BH activity (correlation of radio and Xray radiation) and its spin modification, ie the spin influence on accretion and jet processes. I will finally discuss,  we can derive spin bounds for quasars and these spin values could be used to probe/derive bounds for ultra light boson properties via superradiance such as mass, self-interaction and energy density.