Astronomy Tea Talk
Abstract 1:
Galaxy clusters are the largest gravitationally bound objects in the Universe and as a dense environment are known to have an effect on the galaxies within them. Clusters are dynamical and are often separated into two dynamical states: relaxed and merging (or non-relaxed). In this talk, I investigate if the dynamical state of a galaxy clusters affects the galaxy populations within it. In particular, if and how the dynamical state of a galaxy cluster affects the properties of radio galaxies or radio active galactic nuclei (radio-AGN). I will present a study at high redshift where I use a quantitative method to characterize the dynamical state of a cluster using various morphology parameters and investigate trends of these morphology parameters with radio-AGN luminosity. I will present another study but at low redshift in which colleagues and I explore whether the merging cluster environment has an effect on radio-AGN morphology. We find that it does, but you'll have to come to the talk to find out how!
Abstract 2:
Since the discovery of GW190521—a binary black hole merger with a total mass of ~150 solar masses—and its potential electromagnetic counterpart detected by ZTF in an AGN, the study of transients in AGN accretion disks has grown rapidly. In addition to binary black hole mergers, several other types of catastrophic explosions, such as supernovae, gamma-ray bursts, and neutron star mergers, are also expected to occur within AGN disks. Due to the dense surrounding environments, the electromagnetic properties of these explosions embedded in AGN disks could be significantly different from those occurring in the interstellar medium. They can always produce delayed shock breakout signals and shock cooling emissions following the explosions. Moreover, these dense environments facilitate the generation of strong shocks, which can lead to the production of TeV-PeV neutrinos. In this talk, I will discuss the theoretically predicted properties of both electromagnetic signals and high-energy neutrinos produced by these catastrophic explosions within AGN disks.