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Black Hole at the Center of Our Galaxy Appears to be Getting Hungrier

posted by janrinok on Tuesday September 24 2019, @03:38PM   
from the feed-me,-FEED-ME! dept.

upstart writes:

Submitted via IRC for FatPhil

Black hole at the center of our galaxy appears to be getting hungrier

The enormous black hole at the center of our galaxy is having an unusually large meal of interstellar gas and dust, and researchers don't yet understand why.

"We have never seen anything like this in the 24 years we have studied the supermassive black hole," said Andrea Ghez, UCLA professor of physics and astronomy and a co-senior author of the research. "It's usually a pretty quiet, wimpy black hole on a diet. We don't know what is driving this big feast."

A paper about the study, led by the UCLA Galactic Center Group, which Ghez heads, is published today in Astrophysical Journal Letters.

The researchers analyzed more than 13,000 observations of the black hole from 133 nights since 2003. The images were gathered by the W.M. Keck Observatory in Hawaii and the European Southern Observatory's Very Large Telescope in Chile. The team found that on May 13, the area just outside the black hole's "point of no return" (so called because once matter enters, it can never escape) was twice as bright as the next-brightest observation.

They also observed large changes on two other nights this year; all three of those changes were "unprecedented," Ghez said.

The brightness the scientists observed is caused by radiation from gas and dust falling into the black hole; the findings prompted them to ask whether this was an extraordinary singular event or a precursor to significantly increased activity.

"The big question is whether the black hole is entering a new phase—for example if the spigot has been turned up and the rate of gas falling down the black hole 'drain' has increased for an extended period—or whether we have just seen the fireworks from a few unusual blobs of gas falling in," said Mark Morris, UCLA professor of physics and astronomy and the paper's co-senior author.

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Original Submission

• What I like about this (set of) observation(s) (Score: 3, Insightful) by FatPhil on Tuesday September 24 2019, @10:57PM

  by FatPhil (863) <{pc-soylent} {at} {asdf.fi}> on Tuesday September 24 2019, @10:57PM (#898308) Homepage

  If I dare be serious, then the reason this particularly interests me is that the various stars that orbit close to the black hole itself have a very short orbital period (in astronomical terms), so we will get to see them buzzing the tower, and suffering the consequences, many times over continued observation. S0-2 has a period of a decade and a half, so we have more than one complete circuit already, its orbit is almost completely known. That makes it a great test for General Relativity - if our extrapolations' error bars fail to contain it, there might be some rethinking to do (such as looking for another heavy object that's perturbing it). Talking about other heavy objects that we didn't know about until more recently, the somewhat dark S0–102's due for another closest approach next year, maybe that will give us more energy burps too. The one that interests me the most is S0-16, which has an extremely eccentric elliptical orbit, and from the charts I've seen, one that seems to pass closer to the event horizon than any other (known) star. Alas that only orbits every 3-4 decades, and did periapsis in 2000, so we will need to wait quite a while before we see (with new improved telescopes) how much it sheds on its next fly-by. There are as yet unnamed (according to the Sag-A* wiki page) other stars that are also on less well defined orbits that might also have very close periapses, time will tell. Exciting times - on the assumption world governments keep funding science, which is something I'm thankful for every year it continues.

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