The researchers concluded from their observations that a new type of process causes the growth rate of a black hole to increase within a few months, and identified two other similar events in the universe. The research was published tonight, 14.1.19, in the journal Nature Astronomy
A group of researchers led by Dr. Benny Trachtenbrot and Dr. Yair Hakabi from the Department of Astrophysics at Tel Aviv University determined based on their observations that a completely new mechanism is responsible for the accelerated growth of giant black holes - reaching a mass of up to a billion times that of our Sun. Prof. Hagai Netzer from the Department of Astrophysics at Tel Aviv University participated in the study, as well as researchers from the USA, Chile, Poland and England. The article was published tonight, 14.1.19, in the journal Nature Astronomy.
"Giant black holes, one million to one billion times heavier than our sun, reside at the center of most galaxies in the universe," explains Dr. Trachtenbrot. "At the center of the Milky Way galaxy in which we live, for example, there is a huge black hole with a mass of 4 million solar masses. Despite their prevalence, we still do not know how such black holes grow to such large masses. It is possible that our new findings hint at one of the processes causing this."
Dr. Harkabi adds: "In recent years, a number of dramatic events have been identified in which black holes 'swallow' a star or other material in their vicinity, and grow in this way. An astronomical event known as AT 2017bgt, which was observed in 2017, also initially received this type of interpretation, but various data made us suspect that this time it is a different and unknown process." The first hint of the abnormality of the event was an additional light component (emission lines of oxygen, nitrogen and helium ions) emitted from it, which is not typical of known stellar absorption events. These observations corresponded to Prof. Netzer's theoretical predictions, who says: "Back in the 80s, we predicted that a process in which a black hole swallows gas that is in its vicinity could lead to the observed light components. The new study constitutes the first discovery of the actual process." Another anomaly is the speed of the process: the intensity of the radiation emanating from the black hole's surroundings increased more than 50 times in a very short time - probably just a few months.
The researchers followed the event for over a year with the help of various telescopes, on the ground and in space, and established the assumption that it was unlike anything observed before. Among other things, they collected data using 3 different space telescopes, including the new NICER telescope that is installed on the International Space Station, and the ultraviolet telescope on the Swift satellite (the image that Swift took for the Israeli research was his millionth image, and was cause for a party at ...NASA). Recently, the group of researchers identified two more events in which black holes appear to "light up", while emitting light in a manner similar to that observed in the AT 2017bgt event. The three events constitute a new and intriguing type of accelerated 'feeding' of black holes, in a way that was not known before.
"We are still not sure what causes these black holes to accelerate their growth rate so dramatically and suddenly," says Dr. Trachtenbrot. "There are many mechanisms for accelerating the growth rate of black holes, but most of them occur over much longer periods." Now the researchers are launching a project that aims to discover more such events and track them with the help of a large number of telescopes. "Only in this way will we be able to map the set of ways in which black holes swallow matter, understand what prompts them to do so, and perhaps finally solve the riddle of the formation of these 'monsters' that reside in the centers of galaxies," concludes Dr. Harkabi.
More of the topic in Hayadan:
Comments
The question is over:
Isn't it "obvious" that a super massive black hole with such a strong gravity will attract to it and "swallow" "stray stars" moving around it?
Is there a chance they'll swallow us? I went into hysteria. I look at the sky checking if the stars are approaching us
Do they swallow gas? Gas melted faster... so the black hole grew faster? You did not understand