Astronomers have discovered a hot gas bubble rotating clockwise around the black hole Sagittarius A* - the core of our Galaxy. However, this bubble has not been found directly, but via an accompanying phenomenon: flares in the X-ray range, which have been detected again and again, starting from the black hole Sgr A*. Since nothing can leave the black hole itself, a phenomenon in the immediate vicinity must be responsible - the gas bubble. (more…)

Astronomers have known for a while that the centers of most galaxies are home to supermassive black holes. With ever-improving methods of investigation, they have been able to trace these giants far back into the past. They must have existed as early as 750 million years after the Big Bang. This raises one of the biggest mysteries in astronomy today: How could these supermassive black holes, which weigh millions to billions of times the mass of the Sun, grow so large so quickly? Current theories hold that supermassive black holes begin their lives in the dust-shrouded cores of galaxies…

How did the supermassive black holes come into being, which today are gigantic sentinels in the center of many galaxies? Initially, one proceeded from the obvious: The giants grew by accreting other matter or consuming black holes, that is, by merging with them. Step by step, from small to medium to giant. But this concept has a couple of problems. First, we have not yet been able to detect the necessary intermediate stages. They should still exist, but so far we have only found small black holes - or the really big ones. Problem number 2 is that there…

A lot. If a star is heavy enough (i.e., it is still at least 2.5 solar masses after its supernova), then it continues to collapse until a black hole forms. Such stellar-sized black holes have been forming for quite some time, and more and more are forming. How many are there already? This intriguing question has been addressed by Alex Sicilia, a PhD student under the supervision of Prof. Andrea Lapi and Dr. Lumen Boco of Italy's Scuola Internazionale Superiore di Studi Avanzati. In a first paper just published in the Astrophysical Journal, the authors studied the demography of…

A black hole is an amazing phenomenon. It is invisible because it does not even allow light to escape. Nevertheless, it can be imaged. It concentrates mass in a very small part of space - so small that the conventional laws of physics lose their meaning. Nevertheless, physicists are getting closer and closer to its secrets. One of them is what a black hole looks like inside. Black, it is clear, is not there. Quite the opposite. Inside, all the mass and energy that cannot escape the event horizon are concentrated. If one could see in a black hole,…