Using NASA’s Neil Gehrels Swift Observatory, which launched in 2004, scientists have discovered a black hole in a distant galaxy repeatedly nibbling on a Sun-like star. This remarkable discovery signals a new era of Swift science, made possible by a novel method for analyzing data from the satellite’s X-ray Telescope (XRT). Phil Evans, an astrophysicist at the University of Leicester in the United Kingdom and longtime Swift team member, said “Swift’s hardware, software, and the skills of its international team have enabled it to adapt to new areas of astrophysics over its lifetime. Neil Gehrels, the mission’s namesake, oversaw and encouraged many of those transitions. Now, with this new ability, it’s doing even more cool science.” The object has been named Swift J023017.0+283603 (or Swift J0230 for short) and its study has been published in Nature Astronomy on September 7th. This discovery is an exciting one as it showcases the capabilities of space observatories and demonstrates how much more we can learn about deep space by studying objects such as black holes.
When a star gets too close to a monster black hole, the immense gravitational forces create intense tides that tear the star apart into a stream of gas. The leading edge of the gas is pulled into the black hole and the trailing edge escapes the system. These destructive episodes are known as ‘tidal disruption events’, which astronomers observe as flares of multiwavelength light created when the debris collides with a disk of material already orbiting the black hole. In addition to this, astronomers are now studying variants of this phenomena, known as ‘partial or repeating tidal disruptions’. Here, when an orbiting star passes near a black hole, it bulges outward and sheds material, but does not get completely destroyed. This process repeats itself until the star ultimately loses too much gas and disintegrates. The type of emission scientists observe depends on the characteristics of the star and black hole system, leading to a variety of behaviors to categorize. Examples include an outburst that happened every 114 days around a black hole with 78 million times the Sun’s mass, and another event that occurred every nine hours around a black hole with 400,000 times the Sun’s mass, likely caused by an orbiting white dwarf.