Intermediate-mass black holes are the rarest type of
these extreme objects. Much heavier than a star, but not as massive as those at
the center of galaxies, these black holes have only been identified a handful
of times. Now, a new candidate intermediate-mass black hole has been found
thanks to its gruesome actions: the ripping apart of a star in a distant dwarf
galaxy.
The team had reason to believe that the transient
event AT 2020neh was the destruction of a star by a black hole. Modeling of the
event estimated that the black hole was between 50,000 and 800,000 times the
mass of the Sun. Just for comparison, black holes found with gravitational
waves are often in the tens of times the mass of the Sun. The supermassive
black holes at the center of galaxies can be millions, if not billions, of
solar masses.
"The fact that we were able to capture this
midsize black hole whilst it devoured a star offered us a remarkable
opportunity to detect what otherwise would have been hidden from us,"
first author Charlotte Angus at the Niels Bohr Institute said in a statement.
"What is more, we can use the properties of the
flare itself to better understand this elusive group of middle-weight black
holes, which could account for the majority of black holes in the centers of
galaxies."
Supermassive black holes already existed very early
in the universe – too early for them to make sense in many theories. One
possibility is that the formation of supermassive black holes comes from the
mergers of many intermediate-mass black holes. But to know if that’s correct,
we need to know how many of these black holes exist.
"One of the biggest open questions in astronomy
is currently how supermassive black holes form," added coauthor Vivienne
Baldassare, professor of physics and astronomy at Washington State University.
"If we can understand the population of
intermediate-mass black holes out there – how many there are and where they are
located – we can help determine if our theories of supermassive black hole
formation are correct," explained coauthor Enrico Ramirez-Ruiz, professor
of astronomy and astrophysics at the University of California, Santa Cruz and
Niels Bohr Professor at the University of Copenhagen.
The discovery of this object was possible thanks to
the Young Supernova Experiment, an approach to spot transient events, such as
supernovae or this tidal disruption event, as early as possible. The quick
response was key to the estimation of the black hole's mass. More of such
observations could give us a better understanding of these rare black holes.
Reference: Nature Astronomy.
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