Massive Black Hole Caught in the Act of Swallowing a Star for the First Time
Images from Swift's Ultraviolet/Optical (white, purple) and X-Ray telescopes (yellow and red) were combined to make this view of Swift J1644+57. Evidence of the flares is seen only in the X-ray image, which is a 3.4-hour exposure taken on March 28, 2011.
Issued by University of Leicester Press Office on 24 August 2011
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Scientists from the University of Leicester are part of an international team who have reported observing a supermassive black hole as it pulls apart and swallows a star that got too close.
They report in Nature this week that the event provided astronomers with a rare opportunity to study the birth of a 'relativistic jet' - a high-speed outflow of ionized matter, initiated by the accretion of material from the star into the black hole.
Drs Kim Page, Julian Osborne, Andy Beardmore and Phil Evans from the University of Leicester Department of Physics and Astronomy are co-authors of the paper, which is led by Prof David Burrows of Penn State University.
Dr Osborne said: “A massive black hole is thought to lie at the centre of every decent-sized galaxy throughout the Universe. These naturally exert a strong influence on the central region of their galaxy, and we expect that stars near to the centre will be slowly drawn into the black hole.
Although the slowly-decaying remnants of such an event have been seen on a few occasions, it is only now that we have seen the initial flash that marks this stellar destruction.
“What would happen when a star got too close to a black hole? The strong gravitational force would both compress and stretch the star, heating it to very high temperatures and blowing it apart. Some part of the gas from the star would quickly spiral down into the black hole, likely forming a spinning disk as it did so (much like water going down a plug-hole), while the rest would join this disk a bit later. This is the standard theory, and is consistent with the few sparse late-time observations so far.
“On March 28, 2011, the Swift satellite discovered a new bright hard X-ray source (Swift J1644+57). Unlike the gamma-ray bursts that it was designed to study, this source did not fade away fast, but flared up and down, and only faded very slowly. Observations with other facilities showed that the source was exactly in the centre of a small galaxy, some four billion light-years away. This new source was so bright that it could only come from a new ultra-fast jet directed towards us from a newly-formed disk around the previously unseen massive black hole at the centre of the galaxy. The sudden onset of this new source was due to the rapid formation of a disk immediately following the initial destruction of a star by the black hole. The subsequent rapid variability of the source tells us that the black hole mass, at around 10 million times that of the Sun, is consistent with what is expected for a galaxy of this size.
“Jets directed at us from black holes have been seen before, in systems called 'blazars', but these are all very long-lived and are due to a much more massive disk around the black hole. The onset of a new jet has never been seen before.”
The flaring and decay of the new source, as well as its initial precise position, was measured by the Swift X-ray Telescope. The camera of this telescope was provided by the University of Leicester (with funding from STFC), who continue to support its operation and who provide the UK Swift Science Data Centre http://www.swift.ac.uk/ (funded by the UK Space Agency). Swift is a US/UK/Italian satellite managed by the NASA Goddard Space Flight Center, and operated by Penn State University.
NOTE TO NEWSDESK
For more information, please contact Dr Julian Osborne:
Julian Osborne, Dept of Physics & Astronomy, University of Leicester, Leicester LE1 7RH, GB