Why Black Holes Burst With Light When Galaxies Merge

*** Scientists got good news about the odd behavior of supermassive black holes from NASA's cosmic gossip, the Swift satellite.




Photo by NASA/Swift/NOAO/Michael Koss and Richard Mushotzky The optical counterparts of many active galactic nuclei (circled) detected by the Swift BAT Hard X-ray Survey. Galaxies are in the process of merging. These nuclei were known prior to the Swift survey. Swift has found dozens of new ones in more distant galaxies. - space.com


From Denny: Astronomers finally solve a mystery that has bedeviled them for decades. They have wracked their brains trying to figure out why black holes suddenly "light up" when galaxies collide and merge. It does seem like a contradiction that something that sucks up energy and is "black" could suddenly be lit up like a Christmas tree.

NASA Swift satellite

Astronomers got the good news recently from NASA's Swift satellite that relayed back the information like a good cosmic gossip. The word is that supermassive black holes are lighting up like crazy with hard X-rays when their parent galaxies merge.

The numbers the astronomers throw out to us are massive and practically beyond comprehension. Currently, it's just 1% of supermassive black holes that display this peacock preening behavior of putting on a good show in the universe. What's the amount of energy they give off? It's astounding at 10 billion times the sun's energy. Yeah, I'd say that would qualify them to be labeled as Active Galactic Nuclei or AGN. What an understatement! :)

Our Milky Way Galaxy's center black hole

Supermassive black holes can contain a lot of energy, on the scale of one million to one billion the times of the sun's mass. Oh, gee, our humble little Milky Way galaxy only holds in its black hole about three to four solar masses. It must have a small fuel tank. In fact, by normal standards, our Milky Way black hole is downright quiet. It experiences outbursts and then periods of quiet. Maybe it's sulking like any teenager.

"It's kind of lucky that we're in the 90 percent that aren't very active, so there are not a lot of hard X-rays being produced and coming our way and disturbing Earth's atmosphere," says Meg Urry, an astrophysicist at Yale University in New Haven, Connecticut.

Supermassive black holes

These high-energy displays of supermassive black holes have had scientists creating theories for years. Until now, there was no way to prove or disprove those theories. Now, some of those past theories were confirmed, especially the ones that promoted the idea that the violence of galactic mergers could fuel the growth of central black holes.

"We find that about 25 percent of black holes found by Swift are in the process of merging," comments Michael Koss, University of Maryland in College Park, at a NASA teleconference. "Many of these galaxies are very close to us, so we see the severe distortion of the galaxy shapes," he explained. "In addition, we see that the galaxies are very close to each other and therefore will merge and interact very strongly."

Within the next billion years or so scientists figure about 60% of those active galaxies will merge completely, creating giant black holes.

Scientists know that black holes grow by making like a vacuum cleaner and cleaning up the nearby gaseous material or by merging with other black holes. These galactic mergers are a way for the suppermassive black holes to actually feed as they also grow.

NASA's Swift satellite and NuStar

NASA's Swift satellite's survey range was calibrated for about 650 million light-years away. It watches for gamma-ray bursts. Did you know that gamma-rays are the most powerful form of energy in the universe since the Big Bang?

Get this, in 2012, there will launch the NuStar mission that will make a great complement to Swift. The NuStar uses two sets of mirror arrays. Those arrays will focus hard X-rays. The NuStar will be able to study even more distant galaxies, going deeper into space and back in time, from seven or even eight billion years ago. OK, now I'm impressed.


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Interesting Science News Links

From Denny: Social sites are great! You find the most interesting, and, OK, sometimes just plain odd and weird, headlines. Here are a few I culled for today's enjoyment:

From ScienceDaily.com - Bizarre Walking Bat Has Ancient Heritage - A bizarre New Zealand bat that is as much at home walking four-legged on the ground as winging through the air had an Australian ancestor 20 million years ago with the same rare ability, a new study has found.

From their educational site - University of Hawaii Astronomer Takes Sharpest Picture of Pluto System - this article is from 2007 yet still compelling. "Almost 30 years after the discovery of Pluto's large moon, Charon, a University of Hawaii astronomer has used a ground-based telescope to take an image of the Pluto system that exceeds the sharpness possible with the Hubble Space Telescope." At least that's what they claimed before newer photos have come in. :) There are images of Pluto's THREE moons which makes it interesting for me.

From Space.com way back in 2003 - New Theory: Universe Was Born in a Black Hole - "If black holes and the Big Bang befuddle you, try wrapping your brain around this one: The entire universe may have been created in an explosion inside a black hole." And here I've been wasting my time watching YouTube videos when these guys are a regular laugh riot in how they present their view of science information!

The Independent Science - Why We Swing Our Arms When We Walk - "Although it may seem obvious why people swing each of their arms in opposition to their legs, scientists have puzzled over the practice for many decades because it seemed to serve no mechanical function given that the arms do not touch the ground.

One extreme theory even proposed that arm swinging while walking was hard-wired into the human nervous system and served no modern purpose because it was a vestigial relic left over from when our animal ancestors walked on all fours."

OK, this last one really had me laughing because when does common sense enter into the world of scientific research? Almost never seems to be the answer. Sign me up for grant money; I'll make billions and the world will be a better place!



bat, bizarre, weird, space.com, walking, Hubble Telescope, University of Hawaii, ScienceDaily.com, Big Bang, black holes, Pluto

Astronomy: Twin Black Holes Discovered

From: National Optical Astronomy Observatory

"Finding a needle in a haystack might be easy compared to finding two very similar black holes closely orbiting each other in a distant galaxy.

Astronomers from the National Optical Astronomy Observatory (NOAO) in Tucson have found what looks like two massive black holes orbiting each other in the center of one galaxy. It has been postulated that twin black holes might exist, but it took an innovative, systematic search to find such a rare pair.

The newly identified black holes appear to be separated by only 1/10 of a parsec—a tenth of the distance from Earth to the nearest star. This discovery of the most plausible binary black hole candidate ever found may lead to a greater understanding of how massive black holes form and evolve at the center of galaxies. Their results are published in this week’s edition of the journal Nature.

After a galaxy forms it is likely that a massive black hole can also form at its center. Since many galaxies are found in cluster of galaxies, individual galaxies can collide with each other as they orbit in the cluster. The mystery is what happens to these central black holes when galaxies collide and ultimately merge together. Theory predicts that they will orbit each other and eventually merge into an even larger black hole.

Each black hole is surrounded by a disk of material gradually spiraling into its grasp, releasing radiation from x-rays to radio waves. The two black holes complete an orbit around their center of mass every 100 years, traveling with a relative velocity of 6000 kilometers per second.

Credit: p. Marenfeld and NOAO/AURA/NSF" - Check out the rest of the article with the link above.

From Denny: As someone who does a lot of needle in a haystack kind of research I can really appreciate these guys' efforts! More than that let's celebrate their find, wow! the statistical probability of ever finding this unusual phenomenon...