It is Feasible to Directly Measure Black Hole Masses in the First Galaxies

Abstract

In the local universe, black hole masses have been inferred from the observed increase in the velocities of stars at the centres of their host galaxies. So far, masses of supermassive black holes in the early universe have only been inferred indirectly, using relationships calibrated to their locally observed counterparts. Here, we use the latest observational constraints on the evolution of stellar masses in galaxies to predict, for the first time, that the region of influence of a central supermassive black hole at the epochs where the first galaxies were formed is $directlyresolvable$ by current and upcoming telescopes. We show that the existence of the black hole can be inferred from observations of the gas or stellar disc out to $>0.5$ kpc from the host halo at redshifts $z\gtrsim 6$. Such measurements will usher in a new era of discoveries unraveling the formation of the first supermassive black holes based on subarcsecond-scale spectroscopy with the $JWST$, $ALMA$, and the $SKA$. The measured mass distribution of black holes will allow forecasting of the future detection of gravitational waves from the earliest black hole mergers.

9 pages, 3 figures; version accepted for publication in JCAP

References in corpus (3)

• A wide dispersion in star formation rate and dynamical mass of 10^8 solar mass black hole host galaxies at redshift 6
• Discovery of a close-separation binary quasar at the heart of a z~0.2 merging galaxy and its implications for low-frequency gravitational waves
• A figure of merit for black hole mass measurements with molecular gas

Cited by in corpus (1)

• A Multi-messenger view of Cosmic Dawn: Conquering the Final Frontier