Gravitational Wave Measurement in the Mid-Band with Atom Interferometers

TL;DR

This paper explores the potential of mid-band gravitational wave detectors, especially atom interferometers, to detect and localize signals from compact binaries in the 30 mHz to 10 Hz range, filling a gap in the gravitational wave spectrum.

Contribution

It introduces AIMforGW, a Fisher matrix code for evaluating mid-band GW detector capabilities, and analyzes the performance of terrestrial and satellite detectors for source localization.

Findings

Satellite detectors can achieve sub-degree sky localization for certain sources.

Networks of two terrestrial or one satellite detector provide near-uniform sky coverage.

Mid-band detectors are effective in pinpointing GW source locations.

Abstract

Gravitational Waves (GWs) have been detected in the $\sim$100 Hz and nHz bands, but most of the gravitational spectrum remains unobserved. A variety of detector concepts have been proposed to expand the range of observable frequencies. In this work, we study the capability of GW detectors in the ``mid-band'', the $\sim$30 mHz -- 10 Hz range between LISA and LIGO, to measure the signals from and constrain the properties of ${\sim}$1 -- 100 $M_\odot$ compact binaries. We focus on atom-interferometer-based detectors. We describe a Fisher matrix code, AIMforGW, which we created to evaluate their capabilities, and present numerical results for two benchmarks: terrestrial km-scale detectors, and satellite-borne detectors in medium Earth orbit. Mid-band GW detectors are particularly well-suited to pinpointing the location of GW sources on the sky. We demonstrate that a satellite-borne detector could achieve sub-degree sky localization for any detectable source with chirp mass $\mathcal{M}_c \lesssim 50 M_\odot$. We also compare different detector configurations, including different locations of terrestrial detectors and various choices of the orbit of a satellite-borne detector. As we show, a network of only two terrestrial single-baseline detectors or one single-baseline satellite-borne detector would each provide close-to-uniform sky-coverage, with signal-to-noise ratios varying by less than a factor of two across the entire sky. We hope that this work contributes to the efforts of the GW community to assess the merits of different detector proposals.