Radio Emission From a $z =$ 10.1 Black Hole in UHZ1

TL;DR

This paper estimates radio flux densities from a high-redshift black hole in UHZ1, suggesting future radio telescope observations could detect it and advance understanding of early quasar formation.

Contribution

It provides the first estimates of radio emission from a $z=10.1$ black hole, highlighting the potential for upcoming radio telescopes to observe such objects.

Findings

SKA and ngVLA can detect the black hole with reasonable observation times

Radio detection could complement JWST and X-ray data for early quasars

Radio observations may enable studies of $z \,\sim\, 5-15$ quasars in the future

Abstract

The recent discovery of a 4 $\times$ 10$^7$ M$_{\odot}$ black hole (BH) in UHZ1 at $z =$ 10.3, just 450 Myr after the big bang, suggests that the seeds of the first quasars may have been direct-collapse black holes (DCBHs) from the collapse of supermassive primordial stars at $z \sim$ 20. This object was identified in James Webb Space Telescope (JWST) NIRcam and Chandra X-ray data, but recent studies suggest that radio emission from such a BH should also be visible to the Square Kilometer Array (SKA) and the next-generation Very Large Array (ngVLA). Here, we present estimates of radio flux densities for UHZ1 from 0.1 - 10 GHz, and find that SKA and ngVLA could detect it with integration times of 10 - 100 hr and just 1 - 10 hr, respectively. It may be possible to see this object with VLA now with longer integration times. The detection of radio emission from UHZ1 would be a first test of exciting new synergies between near infrared (NIR) and radio observatories that could open the era of $z \sim$ 5 - 15 quasar astronomy in the coming decade.