Winds of black holes are no longer the same as before

(ORDO NEWS) — During the first billion years of the universe’s existence, the winds blowing from supermassive black holes at the centers of galaxies were much more frequent and powerful than those seen in today’s galaxies some 13 billion years later.

Such winds were so powerful that they slowed down the growth of the supermassive black holes from which they emanated. These are the results of a study led by three scientists from the Italian National Institute of Astrophysics (INAF) in Trieste, published today in the journal Nature.

The work is based on observations of 30 quasars taken with the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile.

Quasars are extremely bright point sources at the cores of distant galaxies, emitted by the intense activity of central supermassive black holes sucking in surrounding matter. The host galaxies of these quasars were observed during the cosmic dawn, when the universe was between 500 million and 1 billion years old.

“For the first time, we have measured the fraction of quasars in the young universe that exhibit black hole winds,” says Manuela Bischetti, an INAF researcher in Trieste and first author of the new study.

“In contrast to what we see in the Universe closer to us, we found that black hole winds in the young Universe are very frequent, have high speeds, reaching 17 percent of the speed of light, and throw a lot of energy into the host galaxy. “.

About half of the quasars observed in this study exhibit black hole winds that are much more common and 20 times more powerful than those known from quasars in closer space when the universe was about 4 billion years old.

“Observations of black holes in the young universe show that they grow much faster than their host galaxies, while in the local universe, as we know, black holes and galaxies co-evolve,” adds study co-author Chiara Feruglio, an INAF researcher in Trieste.

“This means that at some point in the Universe, a mechanism must have worked that slows down the growth of black holes. Our observations allowed us to identify this mechanism in the winds of black holes that occurred when the age of the Universe was 0.5-1 billion years.”

Thus, the energy released by the winds could stop the further accretion of matter onto the black hole, slow down its growth and initiate a phase of “general evolution” between the black hole and its host galaxy.

“This study allowed us to identify an era in the history of the universe when the influence of black hole winds became significant,” Bichetti adds. “This has a huge impact on our knowledge of the initial growth phases of black holes and their galaxies, placing strong limits on the models that describe the formation of the first galaxies.”

The completely unexpected discovery was made possible by high-quality data from the Xshooter instrument installed on the VLT as part of ESO’s large program, which includes about 250 hours of observations.

“Quasars are some of the brightest objects observed in the early universe, but due to their distance they are quite faint in terms of observable magnitude,” explains co-author Valentina D’Odorico of INAF Trieste and chief investigator of the observing program.

The time to observe these objects and the X-shooter’s unique capabilities in terms of efficiency, wavelength coverage and resolution allowed us to obtain very good quality spectra, which made it possible to obtain this interesting result.”

“We’ve had reason to believe for several years that black holes are a billion times more massive than the sun… can launch powerful winds at 20% of the speed of light into their surroundings,” adds Andrea Ferrara, professor at Scuola Normale Superiore (SNS) and study co-author.

“Today we have confirmation of this from data obtained with the European telescope. The SNS contributed to the theoretical interpretation.

The discovery of these spectacular galactic winds at such a distant time could have huge and as yet unexplored consequences for the birth and evolution of galaxies like ours. We will address these issues as we continue this study.”

Initially, the program was not designed for this scientific goal, but assumed the study of intergalactic gas in the early Universe in the first place. Based on information from closer quasars, such winds were thought to be rare.

“Fortunately, we found that these winds are very common in the young Universe, which complicated our analysis, but gave us the opportunity to discover a very important result.”


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