Astronomers observe elusive starlight surrounding ancient quasar Urania

Observations suggest that some of the oldest monster black holes arose from massive cosmic seeds.

MIT astronomers have observed elusive starlight surrounding some of the oldest stars Quasars in the universe. Distant signals dating back to the origins of the universe more than 13 billion years ago reveal clues about the evolution of the early universe black holes I Galaxies.

Quasars are burning centers Active galaxieswhich has an unsaturated nucleus in its nucleus Supermassive black holes. Most galaxies have a central black hole that can sometimes gobble up gas and stellar debris, generating a brief burst of light in the form of a glowing ring as the material spirals toward the black hole.

In contrast, quasars can absorb huge amounts of material over much longer timescales, generating an extremely bright, long-lasting ring – so bright that quasars are among the brightest objects in the universe.

Because they are so bright, quasars outshine the rest of the galaxy in which they are located. However, the MIT team was able to detect faint starlight for the first time in host galaxies of three ancient quasars.

From this elusive stellar flare, scientists estimated the mass of each host galaxy relative to the mass of its central supermassive black hole. It turns out that in the case of these quasars, the central black holes were much larger relative to their host galaxies than their modern counterparts.

discoveries, published A May 6, 2024 issue in The Astrophysical Journal may shed light on how supermassive black holes have become so massive despite the relatively short cosmic time in which they can grow. In particular, these early monster black holes may have emerged from more massive “seeds” than modern black holes.

After the creation of the universe, there were seedlings of black holes, which then absorbed matter and grew in a very short time. – said study author Minghao Yu of the Kavli Institute for Astrophysics and Space Research at MIT. One of the most important questions is understanding how these supermassive black holes can grow so massive and so quickly.

These black holes are billions of times more massive than the Sun, while the universe is still in its early stages – said study author Anna-Kristina Ehlers, assistant professor of physics at MIT. Our results suggest that in the early universe, supermassive black holes could have gained mass before the galaxies that hosted them, and primordial black hole seeds could have been larger than they are today.

Blinding cores
Since quasars were first discovered in the 1960s, their extraordinary brightness has become evident. Quasar light was initially thought to come from a single “point source” similar to a star. However, later observations showed that quasars derive their energy from supermassive black holes located at the centers of galaxies. These black holes are surrounded by accretion disks, where material falls into the black hole, emitting huge amounts of energy in the form of light. Stars in galaxies that host quasars are fainter than their dazzling cores.

Separating the light emitted by the quasar’s central black hole from the light coming from stars in the host galaxy is an extremely difficult task. It’s like trying to create a field of fireflies around a bright light. However, in recent years, astronomers have gotten a head start on launches James Webb Space Telescope (JWST)which can reach farther into the past and observe objects with greater sensitivity and precision than any other existing observatory.

In their new study, Yue and Ehlers used dedicated time at the James Webb Space Telescope to intermittently observe six known ancient quasars from the fall of 2022 until next spring. In total, the team collected more than 120 hours of observations of six distant objects.

The quasar dwarfs its host galaxy by orders of magnitude. Previous images were not sharp enough to distinguish the shape of the host galaxy with all its stars Yu said. Now, for the first time, we are able to detect the light from these stars by closely modeling the sharpest images of these quasars from the James Webb Space Telescope.

Light balance
The team collected JWST image data for six distant quasars, each about 13 billion years old. This data included measurements of the light emitted by each quasar at different wavelengths. The researchers then fed this data into a model that estimated how much light would likely come from a compact “point source.” Accumulation disk around the black hole, compared to a more diffuse source such as light from surrounding stars in the host galaxy.

Using this model, the team separated the light emitted by each quasar into two components: light from the accretion disk around the central black hole and light from more scattered stars in the host galaxy. The amount of light coming from each source corresponds to its total mass. For these quasars, scientists estimated that the ratio of the mass of the central black hole to the mass of the host galaxy was about 1:10. They found that this was a stark contrast to the current mass ratio of 1:1,000, suggesting that the recently formed black holes were much less massive compared to their host galaxies.

This tells us something about what grows first: does the black hole grow first, and then the galaxy catches up with it? Or perhaps the galaxy and its stars grow first, dominating and regulating the growth of the black hole? Ehlers said. We see that black holes in the early universe appear to grow faster than their host galaxies. This is preliminary evidence that the primordial black hole seeds may have been larger at that time.

There must have been some mechanism that caused the black hole to gain mass earlier than its host galaxy during those first billion years. Yu added. This is the first evidence we’ve seen of this, which is exciting.

development:
Agnieszka Novak

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Source: Massachusetts Institute of Technology

In the illustration: This image from the James Webb Telescope shows quasar J0148 circled in red. The two insets show, at the top, the central black hole and at the bottom, a stellar ejection from the host galaxy. Source: Courtesy of researchers; NASA