The winds of the black hole are no longer as they used to be

The winds of the black hole are no longer as they used to be


The artist’s impression of the environment of an oversized black hole in the center of an active galaxy. Credit: ESO / M. Kornmesser

During the first billions of years of the universe, winds blowing from supermassive black holes in the centers of galaxies were much more frequent and stronger than those observed in today’s galaxies, some 13 billion years later. Such winds were so strong that they slowed the growth of the oversized black holes from which they came. These are the results of a study led by three researchers 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 observed with the Very Large Telescope (VLT) at the ESO Paranal Observatory in Chile. Quasars are extremely bright, point sources in the nuclei of distant galaxies, the emission of which results from the intense activity of central oversized black holes that absorb the surrounding matter. The host galaxies of these quasars were observed around the cosmic dawn, when the universe was between 500 million and 1 billion years old.

“For the first time, we measured the fraction of quasars in the young universe showing black hole winds,” said Manuela Bischetti, an INAF researcher in Trieste and lead author of the new study. “Contrary to what we observe in the universe closer to us, we found that winds from black holes in the young universe are very frequent, have high speeds of up to 17 percent of the speed of light and inject large amounts of energy into their galaxy. “

About half of the quasars observed in this study show black hole winds, which are much more frequent and 20 times stronger than those known in the nearest world quasars when the universe was about 4 billion years old.

“Observations of black holes in the young universe show that they are growing much faster than the galaxies that host them, while in the local universe, we know that black holes and galaxies are co-evolving,” added Chiara Feruglio, co-author of INAF researcher in Trieste. . “This suggests that a mechanism must have been operating in the universe at some point, slowing the growth of the black hole. Our observations allowed us to identify this mechanism in the black hole winds produced when the universe was 0.5 to 1 billion years old.” . “

The energy injected by the winds could thus stop the further accumulation of matter in the black hole, slowing its growth and starting a phase of “common evolution” between the black hole and its host galaxy. “This study allowed us to identify the time in the history of the universe when the effect of black hole winds began to be significant,” adds Bischetti. “This has a huge impact on our knowledge of the early developmental phases of black holes and their host galaxies, placing strong constraints on models that describe the formation of early galaxies.”

A completely unexpected discovery was made possible by high quality data from the Xshooter instrument installed on the VLT as part of a large ESO program with approximately 250 hours of observation.

“Quasars are some of the brightest objects that can be seen in the early universe, but because of their distance, they are quite dim in size,” explains Valentina D’Odorico, co-author of INAF in Trieste. the Scuola Normale Superiore in Pisa. and lead researcher of the observation program on which the study is based. “The large investment of time devoted to observing these objects and the X-shooter’s unique capabilities in terms of performance, wavelength coverage and resolution enabled us to obtain very good quality spectra that enabled this interesting result.”

“We have had evidence for some years that black holes 1 billion times the mass of the sun … could send strong winds traveling at 20 percent of the speed of light around them,” adds Andrea Ferrara. . , professor at the Scuola Normale Superiore (SNS) and co-author of the study. “Today, we have confirmation of this thanks to data obtained with a European telescope by a team with strong Italian imagery and leadership. The SNS contributed to the theoretical side of the interpretation. The discovery of these spectacular galactic winds in such distant times could have “It has had huge and still unexplored implications for the birth and evolution of galaxies like ours. We will address these questions in the continuation of this study.”

The program was not originally designed for this scientific purpose, but to study mainly intergalactic gas in the early universe. Based on information from several nearby quasars, such winds were considered rare. “Fortunately, we said, because these features complicate the reconstruction of the native quasar show, they were unwanted by the astronomers in our study of the intergalactic medium along the line of sight,” says D’Odorico. “Unexpectedly, we found that these winds are very common in the young universe, which complicated our analysis, but offered us the opportunity to discover a very important result.”

Webb images of quasars and galaxies surrounding quasars

More information:
M. Bischetti et al, Suppression of black hole growth from strong outflows to redshifts 5,8–6,6, Nature (2022). DOI: 10.1038 / s41586-022-04608-1

Provided by the Italian National Institute of Astrophysics

Reference: The holes of the black hole are no longer as they used to be (2022, 13 May) retrieved on 14 May 2022 from

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