DATE2023.06.29 #Press Releases

Starlight and the first black holes: researchers detect the host galaxies of quasars in the early universe

Overview of the press release

New images from the James Webb Space Telescope have revealed, for the first time, starlight from two massive galaxies hosting actively growing black holes – quasars – seen less than a billion years after the Big Bang. A new study in Nature this week finds the black holes have masses close to a billion times that of the Sun, and the host galaxy masses are almost one hundred times larger, a ratio similar to what is found in the more recent universe. A powerful combination of the Subaru Telescope and the JWST has paved a new path to study the distant universe.

Image : JWST NIRCam 3.6 μm image of HSC J2236+0032 (Credit: Ding, Onoue, Silverman et al.). The zoom-out image, the quasar image, and the host galaxy image after subtracting the quasar light (from left to right). The image scale in light years is indicated in each panel.

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 have started to answer this question with the James Webb Space Telescope (JWST), launched in December 2021. Studying the relation between host galaxies and black holes in the early universe allows scientists to watch their formation, and see how they are related to one another.

The superb sensitivity and the ultra-sharp images of the JWST at infrared wavelengths finally allowed researchers to push these studies to the time when the quasars and galaxies first formed. Just a few months after JWST started regular operations, the team observed two quasars, HSC J2236+0032 and HSC J2255+0251, at redshifts 6.40 and 6.34 when the universe was approximately 840 million years old. The relatively low luminosities of these quasars made them prime targets for measurement of the host galaxy properties, and the successful detection of the hosts represents the earliest epoch to date at which starlight has been detected in a quasar.

Nobunari Kashikawa (Professor : Department of Astronomy), Kazuhiro Shimasaku (Associate Professor : Department of Astronomy) and Kotaro Kohno (Professor : Institute of Astronomy, School of Science) have contributed to this research.

To read the full press release, please visit the website of Kavli IPMU.

Publication details

　Journal
Nature

Title
Detection of stellar light from quasar host galaxies at redshifts above 6

Journal	Nature
Title	Detection of stellar light from quasar host galaxies at redshifts above 6