Supermassive black holes are a bit like cats – they are either napping or they are eating. Unlike cats, they also “burp”, releasing energy after their meals. Astronomers now have spotted a nearby supermassive black hole that has gone through the nap-eat-burp cycle twice in less than 100,000 years.
In a paper published in the Astrophysical Journal, researchers report details of the active nucleus of galaxy SDSS J1354+1327, J1354 for short, located 900 million light-years from Earth. J1354 is orbited by a larger companion galaxy, and the interaction between the two is making material swirl towards the supermassive black hole and push it into its active quasar phase.
“We are seeing this object feast, burp and nap, and then feast, burp and nap once again, which theory had predicted,” lead author Professor Julia Comerford of CU Boulder said in a statement. “Fortunately, we happened to observe this galaxy in a moment where we could clearly see both events.”
The team used two space telescopes (Hubble and X-ray observatory Chandra) and two ground-based facilities (W.M. Keck Observatory in Hawaii and the Apache Point Observatory in New Mexico) to characterize the object.
With this data, the team was able to establish that two signatures – one on the north side and one on the south side of the galaxies – were from the supermassive black hole and they didn’t happen at the same time. The older emission happened about 1 million years before what we see in the galaxy now.
“This galaxy really caught us off guard,” explained Rebecca Nevin, a CU Boulder doctoral student and study co-author. “We were able to show that the gas from the north part of the galaxy was consistent with an advancing edge of a shock wave, and the gas from the south was consistent with an older quasar outflow."
The Chandra observations highlight how intense a supermassive black hole can get. The dust and gas falling towards the black hole are heated to millions of degrees and this hot material ends up shrouding the black hole.
The occasional emission from the black hole helps us understand how these leviathans of the cosmos work. They might not be extremely common, but they are not exactly exotic. Even our own Milky Way and its dormant supermassive black hole had some activity in the past.