Glimmers in the Cosmic Dawn: A Census of the Youngest Supermassive Black Holes by Photometric Variability
Journal article, 2024

We report the first results from a deep near-infrared campaign with the Hubble Space Telescope to obtain late-epoch images of the Hubble Ultra Deep Field, 10-15 yr after the first epoch data were obtained. The main objectives are to search for faint active galactic nuclei (AGN) at high redshifts by virtue of their photometric variability and measure (or constrain) the comoving number density of supermassive black holes (SMBHs), n SMBH, at early times. In this Letter, we present an overview of the program and preliminary results concerning eight objects. Three variables are supernovae, two of which are apparently hostless with indeterminable redshifts, although one has previously been recorded as a z ≈ 6 object precisely because of its transient nature. Two further objects are clear AGN at z = 2.0 and 3.2, based on morphology and/or infrared spectroscopy from JWST. Three variable targets are identified at z = 6-7 that are also likely AGN candidates. These sources provide a first measure of n SMBH in the reionization epoch by photometric variability, which places a firm lower limit of 3 × 10−4 cMpc−3. After accounting for variability and luminosity incompleteness, we estimate n SMBH ≳ 8 × 10−3 cMpc−3, which is the largest value so far reported at these redshifts. This SMBH abundance is also strikingly similar to estimates of n SMBH in the local Universe. We discuss how these results test various theories for SMBH formation.

Author

Matthew J. Hayes

Oskar Klein Centre

Jonathan Tan

University of Virginia

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

R. S. Ellis

University College London (UCL)

Alice R. Young

Oskar Klein Centre

Vieri Cammelli

University of Trieste

Osservatorio Astronomico di Trieste

Jasbir Singh

University of Trieste

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

Istituto nazionale di astrofisica (INAF)

A. Runnholm

Oskar Klein Centre

A. Saxena

University of Oxford

Ragnhild Lunnan

Oskar Klein Centre

Benjamin W. Keller

College of Arts & Sciences

Pierluigi Monaco

National Institute for Nuclear Physics

University of Trieste

Osservatorio Astronomico di Trieste

N. Laporte

Laboratoire d'Astrophysique de Marseille

J. Melinder

Oskar Klein Centre

Astrophysical Journal Letters

2041-8205 (ISSN) 2041-8213 (eISSN)

Vol. 971 1 L16

Massive Star Formation through the Universe (MSTAR)

European Commission (EC) (EC/H2020/788829), 2018-09-01 -- 2023-08-31.

Subject Categories

Subatomic Physics

Astronomy, Astrophysics and Cosmology

DOI

10.3847/2041-8213/ad63a7

More information

Latest update

8/16/2024