At the 234th meeting of the American Astronomical Society, held this Thursday (13), Allison Kirkpatrick, an astrophysicist at the University of Kansas, presented his great discovery: an extremely rare type of galaxy.
Called “cold quasars,” they are incredibly bright and agonizing galaxies, which can change once and for all our understanding of how this type of system “dies.”
Quasars are basically gigantic black holes surrounded by huge amounts of gas and dust, which makes them much brighter than a conventional galaxy. They can be created when two galaxies merge and their black holes collide.
This should happen soon, for example, with our galaxy, the Milky Way, as it is on a collision course with the neighboring galaxy of Andromeda.
This event – to occur only billions of years from now – will signal the end of the two galaxies and the creation of a quasar.
Eventually, the gas and dust will begin to fall into the center of the quasar and be blown into space – this point, according to astronomers, represents basically the end of a galaxy’s life, ie when it lost its ability to form new stars and became “passive”.
However, Kirkpatrick and his team have found that a small fraction of these quasars is still able to deform new stars.
Researchers were able to find 22 quasars at a distance of 6 to 12 billion light-years away, displaying unusual signatures.
Although they appeared to be in the final stages of their lives, however, they still emitted a shiny signature with a lot of dust and cold gas.
Kirkpatrick roughly compared this type of galaxy to a donut – in the center, there is a dead zone where the quasar blew up most of the gas and dust; around (outside) there is a region of star formation, still with abundant gas and dust. According to Kirkpatrick:
These galaxies are rare because they are in the transition phase. We capture them just before the formation of stars in the galaxy is extinct, and this transition period must be very short.
With incredibly strong winds across galaxies, this transition period could last “only” 10 million years, which turns out to be a blink of the universe’s timelines.
In other words, cold quasars are incredibly rare and their identification is undoubtedly a very important step in discovering the “life cycle” of galaxies.