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Artist’s concept of quasar surrounded by glowing dust, gas, and stars.
Data gathered by the Sloan Digital Sky Survey (SDSS) show that a remote quasar mysteriously shut off over just twelve years of observations, and scientists currently look for an explanation.
The team was puzzled by the rapid change in the quasar brightness. They said that they never experienced something like it. The findings were made public at a gathering of the American Astronomical Society on Jan. 8.
Scott Anderson, the leader of the research team who made the discovery, explained that the phenomenon changed his view on the sky. From now on, scientists can no longer see it as ‘unchanging,’ he noted.
Anderson also said that it was a good thing to have the SDSS around because the instrument allowed researchers witness the changes as they were happening. Quasars are often paired with a black hole at the core of a galaxy.
The black holes at the center of galaxies are tremendously massive. For instance, the black hole in question contains the mass of 50 million suns. This is why these black holes are described as supermassive.
But in order to stay that way, these black holes are also extremely hungry. They feast on nearby stars, dust and gas and release radiation and light in return. Researchers have been keeping an eye on the black hole and the quasar around it for more than a decade.
The SDSS allowed the team notice some subtle changes in early 2015. The observatory detected a sudden decrease in the quasar’s luminosity in just 12 years. To understand the sudden changes, the team analyzed observations from other telescopes worldwide.
All data showed that the changes were ‘stunning’ and ‘unprecedented.’ The brightness plunged by a factor of 50 in a decade, and the quasar currently has the brightness of a regular galaxy.
Because the changes were so abrupt, the astronomy community described it as the ‘changing look quasar.’ There were changes in the black hole, as well. SDSS revealed that the black hole was so voracious that it has consumed all the gas around it. And with no gas, astronomers are no longer able to measure the spectroscopic signature of the quasar, which apparently shut off.
The team had two hypotheses for the phenomenon, which were both ruled out. They believed either a cloud of dust outside the host galaxy blocked their view of the supermassive black hole in it or the quasar was no quasar at all, but a temporary flare of radiation emitted by the black hole.
A more plausible explanation is that the quasar run out of food, which is the bright, hot gas around it.
Image Source: Flickr
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