James Webb Telescope detects starlight around early galaxies with bright quasars

The new findings are critical for understanding both the co-evolution of galaxies and their core black holes.
Mrigakshi Dixit
This is an artist's concept of a galaxy with a brilliant quasar at its center.
This is an artist's concept of a galaxy with a brilliant quasar at its center.

NASA, ESA and J. Olmsted (STScI) 

Astronomers have managed to observe the host galaxies with quasars for the first time in the early universe — when it was only 10 percent of its present age.

A quasar is an incredibly bright object powered by an active supermassive black hole. It consumes stellar gas at a remarkably high rate, making its immediate surroundings glow so brightly that it outshines its own galaxy.

Since the discovery of quasars in the late 1950s, scientists have been attempting to examine their host galaxies. And astronomers have finally reached this milestone thanks to the James Webb Space Telescope's excellent sensitivity and long-range vision. 

An international team of astronomers, including those from the Max Planck Institute for Astronomy, conducted this new study. 

“25 years ago, it was amazing to us that we were able to observe host galaxies from 3 billion years back, using large ground-based telescopes. The Hubble Space Telescope allowed us to probe the peak epoch of black hole growth 10 billion years ago. And now we have JWST available to see the galaxies in which the first supermassive black holes emerged,” co-author Knud Jahnke, from the Max Planck Institute for Astronomy, said in a statement.

The observation of the quasars

The quasars in question have been labeled as J2236+0032 and J2255+0251. Fortunately, they are not the brightest, allowing astronomers to use JWST to monitor their surrounding galaxies. 

James Webb Telescope detects starlight around early galaxies with bright quasars
A close-up of the quasar and its galaxy; bottom: the same image with the quasar's light subtracted, so that the host galaxy becomes visible.

As per the official release, these host galaxies became visible when the team meticulously modeled and removed the glow of the quasar. This revealed the most distant starlight from a quasar's host galaxy.

These quasars were first discovered in 2015 and 2017 using a ground-based telescope, the Subaru telescope, operated by the National Observatory of Japan on Mauna Kea in Hawai’i. The light from the two quasars dates back to when the universe was 870 and 880 million years old, respectively.

Measurement of galaxies' masses

The researchers were able to compute the approximate mass of the early galaxies as well as the black holes that powered the quasar. 

The galaxies have a total of 130 and 30 billion solar masses, respectively. In context, the Milky Way galaxy has a stellar mass of around 60 billion solar masses.

According to the statement, the estimated mass of black holes is 1.4 billion and 200 million solar masses. Our galaxy's black hole is just roughly 4 million solar masses in size.

The team said these new findings indicate that early quasars and their host galaxies are extremely similar to present galaxies. 

“For modern galaxies, there is a direct correlation between the mass of a galaxy’s supermassive black hole and the total mass of the galaxy’s stars. The early quasars the astronomers observed show the same relation,” noted the statement. 

Furthermore, the research is critical for understanding the co-evolution of galaxies and holes, and their core blac comprehend supermassive black hole formation in the early universe.

The complete study was published in Nature on June 28 and can be found here.

Study abstract:

The detection of starlight from the host galaxies of quasars during the reionization epoch (z > 6) has been elusive, even with deep HST observations1,2. The current highest redshift quasar host detected3, at z = 4.5, required the magnifying effect of a foreground lensing galaxy. Low-luminosity quasars4,5,6 from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP)7mitigate the challenge of detecting their underlying, previously-undetected host galaxies. Here we report rest-frame optical images and spectroscopy of two HSC-SSP quasars at z > 6with JWST. Using NIRCam imaging at 3.6μm and 1.5μm and subtracting the light from the unresolved quasars, we find that the host galaxies are massive (stellar masses of 13 × and 3.4 × 1010 M⊙, respectively), compact, and disk-like. NIRSpec medium-resolution spectroscopy shows stellar absorption lines in the more massive quasar, confirming the detection of the host. Velocity-broadened gas in the vicinity of these quasars enables measurements of their black hole masses (1.4 × 109 and 2.0 × 108 M⊙, respectively). Their location in the black hole mass - stellar mass plane is consistent with the distribution at low redshift, suggesting that the relation between black holes and their host galaxies was already in place less than a billion years after the Big Bang.

Add Interesting Engineering to your Google News feed.
Add Interesting Engineering to your Google News feed.
message circleSHOW COMMENT (1)chevron
Job Board