Astronomers from the University of Texas and the University of Arizona have discovered a fast-growing black hole in one of the most extreme galaxies known at the edge of the Universe.
The
discovery of the galaxy and the black hole at its center provide new clues
about the formation of the first supermassive black holes. The new work is
published in the Monthly Notices of the Royal Astronomical Society.
Using
observations made with the Atacama Large Millimeter Array (ALMA), a radio
observatory located in Chile, the team has determined that the galaxy, named
COS-87259, containing this new supermassive black hole is very extreme, forming
stars at a rate of 1,000 times more than our Milky Way and containing more than
a billion solar masses of interstellar dust. The galaxy shines as much from
this intense burst of star formation as from the growing supermassive black
hole at its center.
The black hole is considered to be a new type
of primordial black hole, heavily covered in cosmic "dust", emitting
almost all of its light in the mid-infrared of the electromagnetic spectrum.
Researchers have also discovered that this growing supermassive black hole
(often called the active galactic nucleus) generates a powerful jet of material
that travels at close to the speed of light through its host galaxy.
Today, at
the center of almost every galaxy are black holes with masses millions to
billions of times that of our Sun. How these supermassive black holes formed remains
a mystery to scientists, especially since several of these objects have been
found when the Universe was very young. Because light from these sources takes
so long to reach us, we see them as they existed in the past; in this case,
just 750 million years after the Big Bang, which is roughly 5% of the current
age of the Universe.
What is
most surprising about this new object is that it has been detected in a
relatively small area of the sky (less than 10 times the size of the full
Moon), suggesting that there could be thousands of similar sources in the early
Universe. This is a totally unexpected finding from previous data.
The only
other class of supermassive black holes we knew of in the early Universe were
quasars, active black holes relatively poorly hidden by cosmic dust. These
quasars are extremely rare at distances similar to that of COS-87259, with only
a few dozen located across the entire sky. The surprising discovery of
COS-87259 and its black hole raises several questions about the abundance of
very early supermassive black holes, as well as the types of galaxies in which
they typically form.
Ryan
Endsley, lead author of the paper and now a postdoctoral fellow at the
University of Texas said in a statement: "These results suggest that early
supermassive black holes were often heavily obscured by dust, perhaps as a
consequence of intense activity. of star formation in their host galaxies. This
is something that others have been predicting for some years now, and it's nice
to see the first direct observational evidence supporting this scenario."
Similar
objects have been found in the more local current Universe, such as Arp 299
shown here. In this system, two galaxies collide with each other generating an
intense starburst, as well as a strong dimming of the growing supermassive
black hole in one of the two galaxies.
Endsley adds: "While no one expected to find this type of object in the early Universe, its discovery is a step towards a much better understanding of how billion-solar-mass black holes could have formed so early in the life of the Universe, as well as how the most massive galaxies first evolved."