Euclid and Roman with JWST Could Reveal Quasars at up to $z \sim$ 15

TL;DR

This paper explores how upcoming space telescopes like Euclid, Roman, and JWST can detect and study supermassive black holes at very high redshifts (up to z~15), shedding light on early black hole formation and growth.

Contribution

It presents simulated near-infrared luminosities for high-redshift SMBHs, demonstrating the potential for Euclid and Roman to detect them earlier than JWST alone.

Findings

Euclid and Roman can detect SMBHs up to z~14-15.

JWST can spectroscopically confirm redshifts of these SMBHs.

Synergistic observations can reveal SMBH evolution at unprecedented redshifts.

Abstract

Although supermassive black holes (SMBHs) are found at the centers of most galaxies today, over 300 have now been discovered at $z >$ 6, including UHZ1 at $z = 10.1$ and GHZ9 at $z =$ 10.4. They are thought to form when 10$^4$ - 10$^5$ M$_{\odot}$ primordial stars die as direct-collapse black holes (DCBHs) at $z \sim$ 20 - 25. While studies have shown that DCBHs should be visible at birth at $z \gtrsim$ 20 in the near infrared (NIR) to the James Webb Space Telescope (JWST), none have considered SMBH detections at later stages growth down to $z \sim$ 6 - 7. Here, we present continuum NIR luminosities for a BH like ULAS J1120+0641, a $1.35 \times 10^9$ M$_{\odot}$ quasar at $z =$ 7.1, from a cosmological simulation for Euclid, the Roman Space Telescope (RST) and JWST bands from $z =$ 6 - 15. We find that Euclid and RST could detect such BHs, including others like UHZ1 and GHZ9, at much earlier stages of evolution, out to $z \sim$ 14 - 15, and that their redshifts could be confirmed spectroscopically with JWST. Synergies between these three telescopes could thus reveal the numbers of SMBHs at much higher redshifts and discriminate between their evolution pathways because Euclid and RST can capture large numbers of them in wide-field surveys for further study by JWST.