Quasar changing look as a black hole undergoes diet change

A new study by the researchers from Yale University has revealed some intriguing details about the appearances of quasar.

Quasars are described as active luminous galaxies that are powered by giant black holes in their nuclei. Given the understanding that a huge number of quasars were found during the initial days, scientists study quasars to get a better grip on the knowledge that deals with the formation of early universe and galaxies.

Astronomer C. Megan Urry, lead investigator of this work, said that they examined innumerable quasars and found one of them has closed out, an observation likely to shed more light about the lifetimes of these quasars. The team also drew comparisons of the same quasar within an interval of few years and found that the brightness has been softened up by a factor of 7 as far as its magnitude is concerned, suggesting a potential change in the black hole that drives the quasar. Till date, this quasar is known to be the single identified source showing both bright and pale phases.


Associate scientist Stephanie LaMassa termed it like possessing a switch using which the power source dropped down. “Because the life cycle of a quasar is one of the big unknowns, catching one as it changes, within a human lifetime, is amazing,” she added further.


The quasar is catalogued as SDSS J015957.64+003310.5 and found to be deeply inserted within the Stripe 82 region. The scientist, during the course of study, noticed that the weakening of the emission lines of the quasar seemed to be strongly associated with the dimming. The generation of these emission lines use up radiation emitted by the quasar as energy source. As more materials get inside the black hole, it gives rise to more radiation. Therefore, feeble emission lines suggest the black hole has stopped consuming materials.

This finding is extremely interesting as more analysis should lead to clearer understanding about the way these giant black holes were once created.

“It makes a difference to know how black holes grow. This perhaps has implications for how the Milky Way looks today”, Urry concluded.