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Why does this galaxy appear to be smiling? The answer might be because it has been holding a secret that astrophysicists have only now just uncovered: there are two — count ‘em – two gigantic black holes inside this nearby galaxy, named Markarian 739 (or NGC 3758), and both are very active. While massive black holes are common, only about one percent of them are considered as active and powerful – called active galactic nuclei (AGN). Binary AGN are rarer still: Markarian 739 is only the second identified within half a billion light-years from Earth.
Markarian 739 is actually a pair of merging galaxies. For decades, astronomers have known that the eastern nucleus of Markarian 739 contains a black hole that is actively accreting matter and generating an exceptional amount of energy. Now, data from the Swift satellite along with the Chandra X-ray Observatory Swift has revealed an AGN in the western half as well. This makes the galaxy one of the nearest and clearest cases of a binary AGN.
The galaxy is 425 million light-years away from Earth.
How did the second AGN remain hidden for so long? “Markarian 739 West shows no evidence of being an AGN in visible, ultraviolet and radio observations,” said Sylvain Veilleux, a professor of astronomy at University of Maryland in College Park , and a coauthor of a new paper published in Astrophysical Journal Letters. “This highlights the critical importance of high-resolution observations at high X-ray energies in locating binary AGN.”
Since 2004, the Burst Alert Telescope (BAT) aboard Swift has been mapping high-energy X-ray sources all around the sky. The survey is sensitive to AGN up to 650 million light-years away and has uncovered dozens of previously unrecognized systems.
Michael Koss, the lead author of this study, from NASA’s Goddard Space Flight Center and UMCP, did follow-up studies of the BAT mapping and he and his colleagues published a paper in 2010 that revealed that about a quarter of the Swift BAT AGN were either interacting or in close pairs, with perhaps 60 percent of them poised to merge in another billion years.
“If two galaxies collide and each possesses a supermassive black hole, there should be times when both black holes switch on as AGN,” said coauthor Richard Mushotzky, professor of astronomy at UMCP. “We weren’t seeing many double AGN, so we turned to Chandra for help.”
Swift’s BAT instrument is scanning one-tenth of the sky at any given moment, its X-ray survey growing more sensitive every year as its exposure increases. Where Swift’s BAT provided a wide-angle view, the X-ray telescope aboard the Chandra X-ray Observatory acted like a zoom lens and resolved details a hundred times smaller.
The distance separating the two black holes is about 11,000 light-years , or about a third of the distance separating the solar system from the center of our own galaxy. The dual AGN of Markarian 739 is the second-closest known, both in terms of distance from one another and distance from Earth. However, another galaxy known as NGC 6240 holds both records.
Source: Swift Telescope webpage
You can follow Universe Today senior editor Nancy Atkinson on Twitter: @Nancy_A. Follow Universe Today for the latest space and astronomy news on Twitter @universetoday and on Facebook.
It is amazing, I grew up with a time where there was no evidence yet of the existance of a black hole. I grew up where there was no evidence where there were exoplanets. And I probably will say in the future that I grew up when there was no evidence of alien life from present.
We live in wonderful times.
Olaf, Well said. I get very excited each time another exoplanet is discovered. I believe it’s just a matter of time until we discover alien life in some form. I eagerly await the JWST.
Belief isn’t necessary. The statistics game make it pretty inevitable.
I agree.
Me too!
Well said.
It is amazing, I grew up with a time where there was no evidence yet of the existance of a black hole. I grew up where there was no evidence where there were exoplanets. And I probably will say in the future that I grew up when there was no evidence of alien life from present.
We live in wonderful times.
Wow! Will they collide and merge one day?
Wow! Will they collide and merge one day?
In due time they probably will collide. It will probably take several hundred million years.
LC
So it might already have happened, but the light is still on its way 🙂
Is this the result of a galactic merger?
@delphinus
“Markarian 739 is actually a pair of merging galaxies.” taken from the 2nd paragraph of this article.
Mary
What kind of effect will merging AGN have in respect to any possible biospheres within Markarian 739? I imagine such a colossal event will put out a lot of high energy radiation. Could such a merger sterilize large portions of the interior of the galaxy? Or would the radiation emitted be too low?
@Uncle Fred
Yes, the merger of two AGN will increase the radiation background of the host galaxy substantially as you have said. There will be general sterilization occurring over a vast area. “Wish you were here” is not something you would see on travel cards sent back from this general area.
Depending on the orientation of spin for each AGN, the merger will be either extremely energetic or possibly even more energetic than expected currently. In no fashion is it expected the merger will be peaceful over the long run.
Spin works as angular moment during the merger, and well before in fact, to force the BH(s) to interact as charged entities and to repel, attract, break lines of force, all the normal effects you might expect from two charged interacting objects. This is on a much grander scale and the effects may not work the same way as our normal ‘feel’ for them leads us to expect. The EM storms will stamp their own seal on the local area. The chances of anything surviving are slim to extremely poor. Some bacteria which encase themselves may last long enough to restart the cycle of life in that distant future after the radiation levels have fallen or start to point in a different direction as any jets gimbal from the interactions of the SMBHs, accretion disks and whatever mass is added to the mix.
For the amount of radiation; the frequency, the duration and the energy level all play their part in the effects on nearby life, nearby in many cases being many thousands of light years distant if within the zone of any tumbling jets, to many hundreds of light years for the more minor effects such as non-primary cosmic particles emitted from the merged, and merging accretion disks. The gravity waves are expected to be tremendous. Can you imagine the magnetic reconnection events achievable during the lead up to the merger?
The duration of the event(s) leading up to, during the merger, after the merger, and for a long time after the new baby is brought home, indicate to me there will be a general sterilization occurring over a vast area both near the merged AGN and for thousands of light years around the cubic within the galactic plane. Some of this area will be the interior at that time, but in fact much will have happened to cause highly energetic particles well before the actual merger takes place. During the lead up, I imagine, there will be a lot of drifting, loosely aligned mass dragged into the accretion disks of both AGN as well as a bit of ‘stealing the pig’ between these stout fellows. These processes will take a very long time so there will be a lot of radiation over a very long time frame for the galatic inner sections. The gravitational grip each has on the other will certainly affect any lesser matter or mass, potential or static energy sources will literally ‘blow their tops’.
I could go on and on with the descriptions here but your imagination is possibly better than my rather dry wit.
A few papers to give you math nightmares can be found at
Spinning Super-Massive Objects in Galactic Nuclei Up to A* > 1
http://arxiv.org/PS_cache/arxiv/pdf/1101/1101.1364v2.pdf
Do Mergers Spin Up Dark Matter Halos
http://arxiv.org/PS_cache/astro-ph/pdf/0703/0703195v2.pdf
Mary
Probably made a lot of errors, sleep arrives no matter the effort we put to our attempts to forego.
Thanks for the explanation WaxyMary. Nightmarish indeed!
this is probably a stupid question but.. uhm…how can the black holes emit energy into the wider universe from the merger if all their mass is contained within the event horizon? shouldn’t all the energy released from the black holes be curved right back around and fall back towards the singularity?
[In general asking questions isn’t stupid, and indeed it is essential to learning. Science is among other things the process of asking (meaningful) questions.]
My layman’s grasp: Black holes emit energy in several ways (Hawking radiation is a famous example), but here we are meeting relativistic jets.
How energy is extracted into them is still contentious, but at least there are theories:
“Because of the enormous amount of energy needed to launch a relativistic jet, some jets are thought to be powered by spinning black holes. There are two competing theories for how the energy is transferred from the black hole to the jet.
– Blandford-Znajek process.[7] This is the most popular theory for the extraction of energy from the central black hole. The magnetic fields around the accretion disk are dragged by the spin of the black hole. The relativistic material is possibly launched by the tightening of the field lines.
– Penrose mechanism.[8] This extracts energy from a rotating black hole by frame dragging. This theory was later proven to be able to extract relativistic particle energy and momentum,[9] and subsequently shown to be a possible mechanism for the formation of jets.[10]”
So: what DrFlimmer said below.
looks like ive got some reading to do 🙂
thx for the interesting answers, to both of you.
Waxing poetic, but what are the facts?
What are those, and why would they affect bacteria and why would they _not_ effect “encased” bacteria (bacterial spores?)?
That may possibly exist.
The BH jets are lined up with BH spin I take it. Most BHs seems to be fairly lined up with galactic angular momentum. And while AGN pairs are rare it means they have lined up to the observer or they wouldn’t be detected. In the (rare) case presented they are pretty much lined up with the disk.
So likely then, in the initial stage of the process, and in the final stage, merging BHs are lined up with the angular momentum of the galaxy. So the question becomes, how much will they tumble and how much region would that cover? These are very narrow jets.
Yes, they may even shake a meter long crystal one or two atomic radius so that we may finally detect them tremendous waves! =D
MR events is a source of X-rays around a sun; could happen for accretion disk plasma. Do they account for much of observed X-rays?
Waxing poetic, but what are the facts?
What are those, and why would they affect bacteria and why would they _not_ effect “encased” bacteria (bacterial spores?)?
That may possibly exist.
The BH jets are lined up with BH spin I take it. Most BHs seems to be fairly lined up with galactic angular momentum. And while AGN pairs are rare it means they have lined up to the observer or they wouldn’t be detected. In the (rare) case presented they are pretty much lined up with the disk.
So likely then, in the initial stage of the process, and in the final stage, merging BHs are lined up with the angular momentum of the galaxy. So the question becomes, how much will they tumble and how much region would that cover? These are very narrow jets.
Yes, they may even shake a meter long crystal one or two atomic radius so that we may finally detect them tremendous waves! =D
MR events is a source of X-rays around a sun; could happen for accretion disk plasma. Do they account for much of observed X-rays?
Isn’t there another galaxy with two massive black holes: OJ 287, a quasar 3,5 billion lightyears away in the constellation of Cancer.
this is probably a stupid question but.. uhm…how can the black holes emit energy into the wider universe from the merger if all their mass is contained within the event horizon? shouldn’t all the energy released from the black holes be curved right back around and fall back towards the singularity?
What you see does not come OUT of the black hole (that is to say from below its event horizon), but from the very close vicinity around the black hole — but, and this is important, from OUTSIDE the black hole.