'Changing Look' Quasar Both Shines and Dims in the Depths of Space
Astronomers have spotted the first ever "changing look" quasar. This gleaming object is located in deep space and appears to have its own dimmer switch. The finding could offer astronomers a glimpse at the history of these brilliant objects.
Quasars are massive, luminous objects that draw their energy from black holes. Until now, though, scientists have been unable to study both the bright and dim phases of a quasar in a single source. Now, that's changed with the new discovery.
"We've looked at hundreds of thousands of quasars at this point, and now we've found one that has switched off," said C. Megan Urry, one of the researchers, in a news release. "This may tell us something about their lifetimes."
The scientists first noticed the object during ongoing research of Stripe 82, a sliver of the sky found along the Celestial Equator. There, they spotted a weakening of a quasar's broad emission lines. Visible on the optical spectrum, these broad emission lines are signatures of gas that is too distant to be consumed by a black hole, yet close enough to be "excited" by energy from material that does fall into the black hole.
The researchers also ruled out the possibility that the quasar merely appeared to lose brightness due to an object passing in front of it. These findings could be invaluable on several fronts; they provide direct information about the intermittent nature of quasar activity and hint at the sporadic activity of black holes.
"It makes a difference to know how lack holes grow," said Urry. "This perhaps has implications for how the Milky Way looks today."
The findings are published in The Astrophysical Journal.
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