Galaxy Catalogs for Locating Gravitational-wave Events

Abstract:: Gravitational wave transients are caused by some of the most energetic events in the Universe, and a precise location would allow deep examination of the counterpart by electromagnetic waves (telescopes collecting light), the combination of GW and EM resulting in very much improved science return (Multi-messenger Astronomy) . Since the GW detectors do not provide good localization on the sky, the faint counterpart will be very difficult to find. One strategy to help the search is to look first where mass is concentrated and thus the prior probability of GW events is highest. In the first part of this paper, we present methods used to estimate stellar masses and metallicities of galaxies and galaxy clusters in di↵erent catalogues. In the second part of the paper, we test our estimation accuracy by comparing our results with stellar masses given in Stripe 82 Massive Galaxy Catalogue (S82-MGC). Then we present how the stellar mass and metallicity are used to estimate the probability of a galaxy hosting di↵erent types of compact mergers (massive BBH, BBH, and BNS) in the last part of the paper. Our results are provided in an interactive web-based tool (Skymap Viewer) for astronomers to decide where to look first in EM follow-up observations of GW events in the future.

LIGO Document G1601643-x0