Webb discovers mature quasar at cosmic dawn

An international team of astrophysicists used James Webb Space Telescope (JWST) study one of most massive and distant black holesat a distance of 13 billion light years, when The universe was about 800 million years old. Surprisingly, the black hole is powered in the same way as current black holes in the immediate cosmic environment.

Astrophysicists have tried to explain how these black holes in the early stages of the Universe acquired their extraordinary mass. New results published in the journal Nature Astronomyexclude the existence of exotic mechanisms proposed as a possible solution.

Study rules out exotic mechanisms to explain how supermassive black holes in the early stages of the Universe acquired their extraordinary mass

The first billion years of cosmic history pose a challenge: the first known black holes at the centers of galaxies have surprisingly large masses. How did they get so massive and so fast? These new observations provide strong evidence against some proposed explanations, in particular against the extremely efficient feeding regime for increasing the mass of the first massive black holes.

Stars and galaxies have changed greatly over the last 13.8 billion years of the universe’s life. Galaxies have grown and acquired greater mass, either by consuming surrounding gas or (sometimes) by merging with each other. Astronomers have long assumed that supermassive black holes at the centers of galaxies gradually grew along with the galaxies themselves.

Black hole, AGN and quasar

But the growth of black holes cannot be as fast as desired. The falling material forms a bright, hot, rotating “accretion disk.” When this happens around huge black holeresult active galactic nucleus (AGNabbreviation in English), from which large amounts of energy are released as a result of the accretion of gas and dust at the central hole.

The brightest AGN, known as quasars (powerful sources of radiation), 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.

This is why astronomers were surprised when, over the past twenty years, observations of distant quasars revealed very young black holes that nevertheless reached masses of up to 10 billion solar masses. Light takes time to travel from a distant object to us, so looking at distant objects means looking into the distant past.

Quasars of the Cosmic Dawn

We’re seeing the most distant known quasars as they appeared during the era known as the “cosmic dawn.” less than a billion years after the Big Bangwhen the first stars and galaxies formed. Explaining these early massive black holes poses a major challenge to current 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? Eat numerous proposed explanations currently, but none of them are widely accepted.

Deciding which explanation is correct requires a more complete study of quasars than has been available so far. With the advent of the JWST space telescope, particularly the mid-infrared instrument MIRI, astronomers’ ability to study distant quasars has taken a giant leap.

He MIRI device It was built by an international consortium involving scientists and engineers from the Conseil Superior de la Recherche Scientifique (CSIC) and the National Institute of Aerospace Technology (INTA). In exchange for creating the instrument, the consortium received a certain amount of observation time. In 2019, several years before Webb’s launch, the European MIRI consortium decided to use some of this time to observe the most distant quasar known at that time, an object designated J1120+0641.

The study was conducted using Webb’s MIRI mid-infrared instrument and focused on quasar J1120+0641, which occurred just 770 million years after the Big Bang.

The redshift (z) of a light source helps astronomers determine its distance and age. “To date, there are nine confirmed quasars with redshifts greater than 7, and J1120 was the first discovered above (z=7.08), but there are currently three that are further out, with offsets between 7.51 and 7.62 (about 700 million years from the beginning of the Big Bang),” explains one of the authors, Luis Colinafrom the Astrobiology Center (CAB, CSIC-INTA).

Hill and Alvarez Marquez, also from CAB, were responsible for the development of quasar data acquisition and its subsequent calibration, correcting for instrumental effects. The analysis of observations fell on Sarah Bosman

postdoctoral fellow at the Max Planck Institute for Astronomy (MPIA) in close collaboration with Spanish scientists.

Spectrum at different wavelengths

The observations took place in January 2023, during JWST’s first observing cycle, and lasted approximately two and a half hours. They represent the first mid-infrared study of a quasar during the cosmic dawn, just 770 million years after the Big Bang (redshift z=7). Information comes not from the image, but from range: The decomposition of light from a rainbow-shaped object into components of different wavelengths.

“Bull” that doesn’t change

The general shape of the mid-infrared (continuous) spectrum encodes properties big dust bull which surrounds 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 problem of early massive black holes lies in alternative means of rapid growth: the torus, and by extension, the power mechanism in this very early quasar appears to be the same as that of its more modern counterparts.

The only difference is that no model for the rapid early growth of quasars predicted: slightly higher powder temperatureThis is about a hundred Kelvin warmer than the 1300 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 we may be overestimating the masses of early black holes due to extra dust are also not a solution.

quasar broad line region, where clumps of gas rotate around a black hole at close to the speed of light, allowing inferences to be made about the black hole’s mass and the density and ionization of surrounding matter, also seems normal. In almost all properties that can be deduced from the spectrum, J1120+0641 is no different from quasars of more recent eras.

In almost all properties that can be deduced from the spectrum, J1120+0641 is no different from quasars of more recent eras.

“Overall, the new observations only add to the mystery: early quasars are surprisingly normal. Regardless of what wavelengths we observe them at, quasars are almost the same at all times in 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 cosmos was only 5% of its current age.

Primary supermassive black holes

Ruling out a number of alternative solutions, the results strongly support the idea that supermassive black holes originally had significant masses, to use astronomical jargon: “primordial” or “largely sown”.

Supermassive black holes did not form from the remains of the first stars, and then very quickly became massive. Studies such as this show that 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.