Black Hole Goes on Crash Diet and Dims its Quasar

Going on an extreme diet has a similar effect on black holes as it does on humans; it quenches our energy and can drastically change our appearance, according to new research by Yale University astronomers who observed a quasar that has undergone a massive dimming event.

“We’ve looked at hundreds of thousands of quasars at this point, and now we’ve found one that has switched off,” said astronomer C. Megan Urry, the study’s principal investigator. “This may tell us something about their lifetimes.”

Quasars are extremely bright galaxies driven by very active supermassive black holes in their cores. In the early universe, quasars dominated, so astronomers use these objects as a means of understanding how the early universe, and the galaxies it contained, formed.

By comparing observations of the same quasar a few years apart, Urry and her team found that the quasar dimmed by up to 7 orders of magnitude. This suggests something changed with the black hole driving the quasar — potentially a change in diet.

“This is like a dimmer switch,” said associate researcher Stephanie LaMassa. “The power source just went dim. Because the life cycle of a quasar is one of the big unknowns, catching one as it changes, within a human lifetime, is amazing.”

The quasar in question is embedded in the Stripe 82 region along the Celestial Equator and the researchers noticed the dimming event was accompanied by a weakening of the quasar’s broad emission lines. These emission lines, that can be detected in optical wavelengths, are generated by surrounding clouds of gas being ‘excited’ or energized by the radiation from the quasar itself. This radiation is generated by material falling into the black hole, so the weakening of the emission lines suggests the black hole in the quasar’s core has stopped consuming matter.

Read more at Discovery News