Recent LIGO-Virgo discoveries

TL;DR

This paper reviews recent gravitational-wave detections by LIGO-Virgo, highlighting new sources, their astrophysical implications, and tests of general relativity from the third observing run in 2019.

Contribution

It provides a comprehensive summary of the first half of LIGO-Virgo's third observing run, including new discoveries and their significance.

Findings

39 new gravitational-wave signals detected

Unprecedented sources like unequal mass black holes and massive neutron stars identified

Enhanced tests of general relativity and insights into compact object populations

Abstract

The LIGO and Virgo gravitational-wave detectors carried out the first half of their third observing run from April through October 2019. During this period, they detected 39 new signals from the coalescence of black holes or neutron stars, more than quadrupling the total number of detected events. These detections included some unprecedented sources, like a pair of black holes with unequal masses (GW190412), a massive pair of neutron stars (GW190425), a black hole potentially in the supernova pair-instability mass gap (GW190521), and either the lightest black hole or the heaviest neutron star known to date (GW190814). Collectively, the full set of signals provided astrophysically valuable information about the distributions of compact objects and their evolution throughout cosmic history. It also enabled more constraining and diverse tests of general relativity, including new probes of the fundamental nature of black holes. This review summarizes the highlights of these results and their implications.