Astronomers have discovered proof of a pair of dwarf galaxies with massive
black holes on a crash path with one another for the first time. Actually,
they've discovered two pairs instead of just one.
The first merger pair of dwarf galaxies is located in the galaxy cluster
Abell 133, which is about 760 million light-years from Earth, and the second
pair is located in the galaxy cluster Abell 1758S, which is about 3.2
billion light-years distant.
It is anticipated that these observations and subsequent research will
reveal some of the mysteries of the very early Universe, when couples of
colliding dwarf galaxies with black holes were much more frequent.
Astronomers have discovered numerous instances of black holes on collision
paths in big galaxies that are nearby, but hunts for them in dwarf galaxies
are much more difficult and have, up until now, failed, according to
research leader Marko Micic of the University of Alabama.
These studies are difficult because it is difficult to see the fainter
light signatures of these galaxy couples due to their smaller sizes. While
our own Milky Way contains the equal of about 60 billion Suns, these
galaxies have stars with total masses that are less than about 3 billion
times that of the Sun.
The researchers used data from several observatories, including optical
data from the Canada-France-Hawaii Telescope, infrared data from WISE, and
X-ray findings from Chandra, to make their discovery. The X-ray data, which
detected the stronger signs being emitted by the black hole couples, was
essential.
The Abell 133 merging seems to be much further along, as evidenced by the
fact that it only has the moniker Mirabilis. That's named after a critically imperiled hummingbird
that is noted for having a very long tail in allusion to the
collision-induced long tail seen around these two galaxies.
With respect to Abell 1758S, the dwarf galaxies are not as closely knit
together and are given the titles Elstir and Vinteuil (after characters from
Marcel Proust's
In Search of Lost Time). These galaxies and their black holes don't appear to have combined to
the same degree; instead, it appears that they are presently connected by a
bridge of stars and gas.
Astrophysicist Olivia Holmes of the University of Alabama states, "Using
these systems as analogs for ones in the early Universe, we can dig down
into issues about the first galaxies, their black holes, and the star
formation the collisions produced."
These smaller, colliding galaxies are believed to have grown together over
billions of years to form the bigger galaxies (like the Milky Way) that now
predominate the Universe. They are referred to as our
"galactic progenitors" by the experts.
We might even be able to learn more about how our own galaxy formed and
progressed to its current state. Our native system still has a number of
discrepancies that need to be explained.
As our telescope and picture processing technology continues to advance,
astronomers will be able to confirm that these dual active galactic nuclei
(DAGN) are indeed what they claim to be and gather more information about
them.
According
to astronomer Jimmy Irwin from the University of Alabama, "Follow-up
observations of these two systems will enable us to investigate processes
that are essential for comprehending galaxies and their black holes as
infants."
The research has been accepted for publication in
The Astrophysical Journal
and is available to read on the preprint server
arXiv.
