Chasing Transients: Constructing Local Galaxy Catalogs for Electromagnetic Follow-Up of Gravitational Wave Events

Abstract

Gravitational waves (GWs) provide a new window for observing the universe which is not possible using traditional electromagnetic (EM) wave astronomy. The coalescence of compact object binaries, such as black holes (BHs) and neutron stars (NSs) generates “loud" GW signals that are detectable by the LIGO-Virgo-KAGRA (LVK) GW Observa- tory. If the binary contains at least one NS, there is a possibility that an observable EM counterpart will be launched during and/or after the merger. The first joint detection of GW radiation (GW170817) and its EM counterpart (AT 2017gfo) greatly extended our understanding of the universe in many fields, such as the birth of heavy elements and the independent measurements of Hubble constant; it also announced the era of multi- messenger astronomy (MMA). As the early EM emission in optical and infrared, known as the kilonova (KN) fades rapidly in hours to days, prompt follow-up of the counterpart is essential. However, it is challenging due to the large localizations of the GW events and numerous distant false positives enclosed. Since GW170817, unprecedented EM follow- up efforts have been made during LVK’s latest third observing run (O3), but no EM coun- terparts were identified. In this dissertation, I present the details of my work with the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration in where I helped improve the efficiency of EM follow-up to GW events by constructing galaxy catalogs in the local universe.