One Year and One Night to 1% in H 0: Efficient Spectroscopic Strategy for Dark Siren Cosmology

arXiv:2607.17284 · astro-ph.CO, gr-qc · Submitted 2026-07-19 · Read on arXiv

Yixuan Dang, Ariel J. Amsellem, Ignacio Magaña Hernandez, Antonella Palmese, B. S. Sathyaprakash

astro-ph.CO, gr-qc

Submitted: 2026-07-19

License: http://creativecommons.org/licenses/by/4.0/

The gist: Gravitational-wave events from compact binary coalescences (CBCs) can be used as standard sirens: they encode the luminosity distance to their sources, which yields a measurement of the Hubble

Terminology

Abstract

Gravitational-wave events from compact binary coalescences (CBCs) can be used as standard sirens: they encode the luminosity distance to their sources, which yields a measurement of the Hubble constant (H 0) if the source's redshift is known. In the absence of an electromagnetic counterpart, H 0 can still be inferred statistically from the cataloged galaxies within the event's sky localization volume via the dark siren, or galaxy catalog method. In this work we examine how the depth of a volume-limited galaxy catalog affects this inference and identify the most efficient spectroscopic strategy for an unbiased measurement of H 0 at a median precision of 0.98%. The strategy is to carry out spectroscopic surveys to a depth of r about 19 for the ten best-localized events observed in one year by the LIGO Hanford, LIGO Livingston, and LIGO-India network at A# sensitivity. Such a campaign requires a minimum of one night of electromagnetic follow-up observations, or five nights under the most conservative assumptions. For the Hanford, Livingston, and Virgo network at A + sensitivity, the same ten-event strategy yields a median precision of 2.63%.

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