The Sensitivity of the Advanced LIGO Detectors at the Beginning of Gravitational Wave Astronomy

TL;DR

This paper discusses the initial sensitivity achievements of Advanced LIGO detectors, highlighting noise understanding, improved detection ranges, and the first gravitational wave observation from a binary black hole merger.

Contribution

It reports the first observation run of Advanced LIGO, detailing sensitivity improvements and the detection of GW150914, marking a milestone in gravitational wave astronomy.

Findings

Achieved strain sensitivity better than 10^{-23}/√Hz at 100 Hz.

Detected gravitational waves from binary black hole coalescence GW150914.

Increased observable volume of the universe by factors of 69 and 43 for black holes and neutron stars.

Abstract

The Laser Interferometer Gravitational Wave Observatory (LIGO) consists of two widely separated 4 km laser interferometers designed to detect gravitational waves from distant astrophysical sources in the frequency range from 10 Hz to 10 kHz. The first observation run of the Advanced LIGO detectors started in September 2015 and ended in January 2016. A strain sensitivity of better than $10^{-23}/\sqrt{\text{Hz}}$ was achieved around 100 Hz. Understanding both the fundamental and the technical noise sources was critical for increasing the observable volume in the universe. The average distance at which coalescing binary black hole systems with individual masses of 30 $M_\odot$ could be detected was 1.3 Gpc. Similarly, the range for binary neutron star inspirals was about 75 Mpc. With respect to the initial detectors, the observable volume of Universe increased respectively by a factor 69 and 43. These improvements allowed Advanced LIGO to detect the gravitational wave signal from the binary black hole coalescence, known as GW150914.