Scientists caught an unusual sky activity: a sleeping black hole suddenly awaken to devour a close-by star.
Almost 90% of the black holes are inactive, not consuming any matter and not producing radiation or light. The tidal disruption event happens when a sleeping black hole becomes active and attracts a passing-by star.
What becomes of the star is not at least as elegant as it may seem. The star undergoes spaghettification; it stretches vertically, and it compresses into long shapes. No object can resist a black hole.
Researchers from University of Michigan and University of Maryland are the first ones to observe the X-rays created by an awaking black hole. The team focused on the accretion disk, which is the halo containing the star’s remains after the occurrence of the tidal disruption.
The event in question was named Swift J1644+57, and it was first observed in 2011 in the center of a galaxy from the Draco constellation. It is believed that the sacrificed star was a white dwarf, a very dense object composed of electron-degenerate matter.
As the uncommon tidal disruption attracted the attention of all international space observers, the scientists had data from four different satellites managed by NASA, the European Space Agency, and the Japanese Aerospace Exploration Agency.
It was initially thought that X-rays were created somewhat at a distance from the black hole. However, the new information on the 2011 event shows that X-rays can originate directly from the accretion disk.
Scientists are interested in how sleeping black holes react because they represent a vast majority of gravitational anomalies in spacetime.
“If we only look at active black holes, we might be getting a strongly biased sample. It could be that these black holes all fit within some narrow range of spins and masses. So it’s important to study the entire population to make sure we’re not biased,” said Chris Reynolds, astronomy professor at University of Maryland.
Swift J1644+57 can also reveal the secrets to how a supermassive black hole reaches its enormous mass, million times larger than the one of our Sun.
The team of researchers created a map of the accretion disk by measuring the X-ray reverberations across the iron atoms. The technique was invented in the last years and involves making predictions based on the delay time observed in X-rays’ trajectories.
The plans for the future are to use the same method to measure the movement characteristics of the sleeping black hole. Moreover, the researchers intend to prolong their observations not only to the moment when the black hole captures and devours the star, but also to the stage where the black hole cools off and returns to the dormant state.
Image Source: Wikipedia