Scientists discover black hole of unexplained mass thanks to observations by James Webb telescope

Looking back, it became clear that It took almost as long for light from the galaxy J1120+0641 to reach Earth. how the universe evolved to the present day. It is inexplicable how the black hole at its center could weigh more than a billion solar masses, as independent measurements have shown.

Recent observations of material in the vicinity of the black hole should have revealed a particularly efficient feeding mechanism, but they found nothing special. This result is even more unusual: It could mean that Astrophysicists know less about the evolution of galaxies than they thought. And yet, they don’t disappoint at all.

These findings are published in the journal Nature Astronomy.

The first billion years of cosmic history present a complex problem: first Known black holes at the centers of galaxies have surprisingly large masses. How did they become so massive and so fast? The new observations described here provide compelling evidence against some proposed explanations, particularly the “super-efficient feeding regime” of early black holes.

Limits to the growth of a supermassive black hole

The stars and galaxies have changed significantly during the last 13.8 billion years, the life of the Universe. Galaxies grew and acquired greater mass either by absorbing surrounding gas or (sometimes) by merging with each other. For a long time, Astronomers have suggested that supermassive black holes at the centers of galaxies gradually grew along with the galaxies themselves..

But The growth of black holes cannot be as fast as desired. Matter falling into a black hole forms “accretion disk“bright, hot and spinning. When this happens around a supermassive black hole, the result is an active galactic nucleus. The brightest objects known as quasars, are among the brightest astronomical objects in all of space. But this brightness limits the amount of matter that can fall into the black hole: the light exerts pressure that can prevent additional matter from falling.

How did black holes become so massive and so fast?

That’s why astronomers were surprised when, over the past twenty years, Observations of distant quasars reveal very young black holes which, however, reached masses up to 10 billion solar masses . Light takes time to travel from a distant object to us, so looking at distant objects is looking into the distant past. We see the most distant known quasars as they appeared during the era known as “cosmic dawn“less than a billion years after the Big Bang, when the first stars and galaxies formed.

Explaining the emergence of the first massive black holes is a difficult task significant for modern models of galaxy evolution. Could it be that early black holes were much more efficient at accumulating gas than their modern counterparts? Or could the presence of dust have influenced estimates of the mass of quasars in such a way that researchers overestimated the masses of early black holes? Currently, many explanations have been proposed, but none have received widespread acceptance.

A Closer Look at the Early Growth of Black Holes

Deciding which explanation (if any) is correct requires a more complete picture of quasars than has previously been available. With the advent of JWST Space TelescopeIn particular, the mid-infrared instrument of the MIRI telescope, astronomers’ ability to study distant quasars has taken a giant leap. To measure the spectra of distant quasars MIRI is 4000 times more sensitive than any previous instrument..

Instruments such as MIRI are created by international consortia in which scientists, engineers and technicians work closely together. Naturally, the consortium is very interested in making sure its tool works as planned.

In exchange for building the instrument, consortia typically receive a certain amount of observation time. In 2019, a few years before JWST launched, The European consortium MIRI decided to use part of this time to observe the most distant quasar known at that time.object having a designation J1120+0641.

Observation of one of the first black holes

The analysis of observations fell to the doctor’s lot. Sarah Bosman, research fellow at the Max Planck Institute for Astronomy (MPIA) and member of the European MIRI consortium. MPIA’s contributions to the MIRI instrument include the creation of a number of key internal parts. Bosman was asked to join the MIRI collaboration specifically to provide expertise on how best to use the instrument to study the early Universe, especially the first supermassive black holes.

Observations were carried out in January 2023., during JWST’s first observing cycle, and lasted approximately two and a half hours. They make up the first mid-infrared study of a quasar during the cosmic dawn, just 770 million years after the Big Bang. (redshift z=7). The information comes not from the image, but from the spectrum: the rainbow breakdown of an object’s light into components of different wavelengths.

Tracking fast moving dust and gas

The general shape of the mid-infrared (“continuum”) spectrum encodes the properties of the large torus of dust surrounding the accretion disk of typical quasars. This torus helps guide matter toward the accretion disk, “feeding” the black hole..

Bad news for those whose preferred solution to the first massive black holes problem is alternative means of rapid growth: the torus, and thus the feeding mechanism, in this very early quasar appears to be the same as those of its more modern counterparts. The only difference is that no model of rapid early quasar growth predicted: a slightly higher dust temperature, about a hundred Kelvin warmer than the 1,300 K found for the hottest dust in less distant quasars.

The shorter wavelength part of the spectrum, dominated by emissions from the accretion disk itself, shows that for us distant observers, the quasar’s light is not obscured by more dust than usual. Arguments that perhaps we are simply overestimating the masses of the first black holes due to the extra dust are also not a solution.

The first quasars are ‘surprisingly normal’

The quasar’s broad line region, where clumps of gas orbit the black hole at speeds close to the speed of light, allowing inferences to be made about the black hole’s mass and the density and ionization of the surrounding matter, also appears normal. In almost all properties that can be inferred from the spectrum, J1120+0641 is no different from quasars of later times..

“Overall, the new observations only add to the mystery: the first quasars were surprisingly normal. No matter what wavelengths we observe them at, quasars have been virtually the same throughout the history of the universe.“, says Bosman. Not only the supermassive black holes themselves, but also the mechanisms that power them, apparently were already fully “mature” when the age of the Universe was only 5% of its current age.

After ruling out a number of alternative solutions, the results provide strong support for the idea that Supermassive black holes have had significant masses from the very beginning, in astronomical jargon: they are “primordial” or “big seeds.”. Supermassive black holes did not form from the remains of the first stars, and then very quickly became massive. They must have formed early with an initial mass of at least one hundred thousand solar masses, presumably from the collapse of huge early gas clouds.

Link

Sarah E.I. Bosman et al. A mature quasar at cosmic dawn, revealed using infrared spectroscopy of the resting system by JWST, Nature Astronomy (2024). DOI: 10.1038/s41550-024-02273-0