Starlight and primordial black holes: Researchers identify galaxies that contained quasars in the early universe.

New images from the James Webb Space Telescope (JWST) have revealed, for the first time, starlight from two supermassive galaxies with expanding black holes – quasars – seen less than a billion years after the Big Bang. A new study in Nature They have found that black holes have a billion times more mass than the sun, and the galaxies that contain them are a hundred times more massive, the same number found in the recent universe. The powerful combination of the Subaru Telescope and JWST has opened up a new avenue for the study of distant astronomy.

The existence of such massive black holes in the distant universe has raised more questions than answers for astronomers. How could these black holes have grown so large when the universe was so small? Amazingly, what has happened in this universe shows a close relationship between the large galaxies that it inhabits. Galaxies and black holes have completely different sizes, so what came first: black holes or galaxies? This is a “chicken-or-egg” problem on a cosmic scale.

An international team of researchers, led by Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Project Researcher Xuheng Ding and Professor John Silverman, and Peking University Kavli Institute for Astronomy and Astrophysics (PKU-KIAA) Kavli Astrophysics Fellow Masafusa Onoue will begin to answer this question with JWST, which was launched in December 2021. Studying the relationship between galaxies that exist and black holes in the early universe allows scientists to look at their structure, and see how they interact.

Quasars are bright, while the galaxies they host are faint, which has made it difficult for researchers to detect the faint light of this galaxy in the glow of quasars, especially at great distances. Before JWST, the Hubble Space Telescope could detect galaxies with bright quasars when the universe was at least 3 billion years old, but nothing younger.

The high sensitivity and sharp images of JWST at infrared wavelengths eventually allowed researchers to push these studies to the time when quasars and galaxies formed. A few months after JWST began regular operation, the team observed two quasars, HSC J2236+0032 and HSC J2255+0251, at redshifts 6.40 and 6.34 when the universe was about 860 million years old.

The two quasars were discovered by the 8.2m Subaru Telescope on the Maunakea Peninsula in Hawai’i. The low luminosity of these quasars made them prime targets for measuring the properties of galaxies, and the successful detection of these clusters represents the earliest time to date that starlight has been detected in a quasar.

Images of the two quasars were captured at infrared wavelengths of 3.56 and 1.50 microns by JWST’s NIRCam instrument, and the galaxies that resided there were revealed after careful sampling and subtraction of light from black holes. The host galaxy’s stellar signature was also observed in JWST’s NIRSPEC spectrum of J2236+0032, supporting the identification of the host galaxy.

An impressive photometry galaxy survey found that these two quasar host galaxies are massive, spanning 130 and 34 billion solar times, respectively. Measuring the speed of the turbulent gas near the quasars from the NIRSPEC spectrum shows that the black holes that power them are also massive, measuring 1.4 and 0.2 billion solar times. The ratio of black holes to host galaxies is the same as the most recent galaxies, meaning that the relationship between black holes and their hosts was already 860 million years after the Big Bang.

Ding, Silverman, Onoue and colleagues will continue this study with a larger model using the Cycle 1 JWST observatory, which will constrain models of the evolution of black holes and their host galaxies. The team recently learned that it has been granted additional time for JWST to study the galaxy J2236+0032 in more detail.