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Astronomers have identified a bumper crop of dual supermassive black holes in the centers of galaxies. This discovery could help astronomers better understand how giant black holes grow and how they may produce the strongest gravitational wave signals in the Universe.
The new evidence reveals five pairs of supermassive black holes, each containing millions of times the mass of the Sun. These black hole couples formed when two galaxies collided and merged with each other, forcing their supermassive black holes close together.
The black hole pairs were uncovered by combining data from a suite of different observatories including NASA's Chandra X-ray Observatory, the Wide-Field Infrared Sky Explorer Survey (WISE), and the ground-based Large Binocular Telescope in Arizona.
"Astronomers find single supermassive black holes all over the universe," said Shobita Satyapal, from George Mason University in Fairfax, Virginia, who led one of two papers describing these results. "But even though we've predicted they grow rapidly when they are interacting, growing dual supermassive black holes have been difficult to find."
Seeing double: Scientists find elusive giant black hole pairs
-- submitted from IRC
(Score: 4, Interesting) by bzipitidoo on Thursday October 05 2017, @02:31PM (9 children)
What sort of gravity wave would the merger of 2 supermassive black holes make?
The merger of stellar mass black holes of about 30 suns convert an incredible 3 suns worth of mass into energy in an instant. I mean, our sun has been powering life on Earth for about 4 billion years, with just a tiny fraction of the energy it radiates in all directions, and these mergers eat up at least 300x all the energy that has ever reached the Earth from the Sun, in a few seconds, maybe less.
Going with 5% as a rule of thumb, a merger of 4 million solar mass black holes might convert 400,000 solar masses worth of matter into gravitational wave energy. Where does all that energy ultimately go? Heat? Expansion of the universe? It's such an inconceivably large amount of energy it's hard to imagine it makes a few waves which quickly fade away and that's all.
(Score: 2) by bob_super on Thursday October 05 2017, @04:29PM (2 children)
> it's hard to imagine it makes a few waves which quickly fade away
"a few waves" which can be detected 1.4 (+/- 0.6) Billions light-years away/later in some random other system. by a detector that is 4km long, representing what infinitesimal fraction of a degree?
Surfing that small wave from less than a few hundred light-years away would warp you to mush (or whatever your heart and blood do when the time and space on your feet doesn't match with your chest).
> from the better-pairs-than-trios dept.
I'm sorry, I'm in a mood to get offended. Can we specify the gender of the black holes?
(Score: 0) by Anonymous Coward on Thursday October 05 2017, @06:56PM (1 child)
> Surfing that small wave from less than a few hundred light-years away would warp you to mush (or whatever your heart and blood do when the time and space on your feet doesn't match with your chest).
Really? I doubt it. Care to explain the mechanism?
(Score: 0) by Anonymous Coward on Thursday October 05 2017, @11:03PM
(Score: 2) by stormwyrm on Thursday October 05 2017, @10:52PM (5 children)
Such supermassive binary black holes are already emitting very low frequency gravitational waves as they orbit each other, of the order of nanohertz. The wavelength of such very low frequency waves is something of the order of 32 light-years, much too low-frequency to be detected by something like LIGO. A pulsar timing array might be the only way we might be able to detect such gravitational waves.
If the gravitational waves from stellar black hole mergers could cause a detector a billion light years away to stretch and shrink by a fraction of an atom's length, what sort of stretching and shrinking do you suppose an observer very close to the merger would experience? I imagine if there were planetary systems close to the black hole mergers detected so far they would experience some pretty violent earthquakes as the black holes merged. A pair of supermassive black holes merging would involve even more energy, of course, and I could imagine that the conversion of 400,000 solar masses into gravitational wave energy by the merger might well cause a massive disruption in all the other normal matter nearby, and in a galactic core, there's plenty of that to go around. It's perhaps one way that a quasar or other active galactic nucleus might get started. The waves interact with matter, and since ordinary matter experiences friction when compressed and stretched, there will be conversion of gravitational wave energy into heat, and a hell of a lot of heat I can imagine, enough heat to get a quasar going looks like!
Numquam ponenda est pluralitas sine necessitate.
(Score: 2) by maxwell demon on Friday October 06 2017, @08:50AM (4 children)
Well, it's easy to calculate: For a wave emanating from a localized source, the amplitude is inversely proportional to the distance (because the intensity is inversely proportional to the square of the distance, and proporional to the square of the amplitude). According to the paper, there was a strain of the order 10-21. I think that means that the length change is 10-21 of the length. The distance was abot 1.4 billion light years, which is ; since we are after orders of magnitude, let's simplify that to 1 billion light years. A light year is slightly below 1016 meters. So the source was about 1025 meters away.
Let's assume you were about as for from that event as the Earth is from the Sun, which is about 1011 meters. Then assuming my interpretation is right, this would give a strain of 1025-11-21=10-7. For a person of 2 meters, this would mean a stretch by about 0.1 µm. Doesn't sound lethal to me.
Make the distance closer, like Earth-Moon distance, at about 4·108 meters, a factor of 250. Then the stretch of that man would be about 25 µm, still doesn't sound too bad to me. (I'm ignoring that the far-field approximation almost certainly won't be valid any more at such short distances).
Let's go about an earth diameter away, 6·106 meters. This gives a stretch of the 2 meter person by about 0.8 mm. However, at that distance I guess you're more likely to die from the near-field effects (in particular, tidal forces).
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by stormwyrm on Friday October 06 2017, @12:14PM (3 children)
Numquam ponenda est pluralitas sine necessitate.
(Score: 2) by maxwell demon on Friday October 06 2017, @04:08PM (2 children)
Not every cell. The body as a whole. Every cell gets only a tiny fraction of it. Indeed, human cells have sizes in the µm range (a factor of about 10-6 to the total body size), therefore their stretch would be in the range of 0.1 pm (that's a fraction of the size of an atomic nucleus). Doesn't sound deadly, does it?
Ah, changing the goalpost …
You surely mean the diameter. The radius is half of that.
Seismic/volcanic activity doesn't care the slightest about the whole-planet deformation; it only cares about the local stresses. Note that the moon also deforms earth about 0.1 meter; that's about 10% of the value you give (though admittedly at a far lower frequency). Now I don't know enough about seismology/geology to tell whether this could trigger some earthquakes; probably it could. But I'm sure it would be much less dramatic than you picture.
Also note that at that distance, the non-wave gravitational effects (that is, the varying gravitational/tidal forces, varying at the same frequency as the gravitational waves) would already be quite large (remember, we are talking about 30 solar masses), so I'd expect that to be the main problem of a planet at that distance.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by stormwyrm on Saturday October 07 2017, @01:18AM (1 child)
Numquam ponenda est pluralitas sine necessitate.
(Score: 2) by maxwell demon on Saturday October 07 2017, @06:28AM
I have no idea what it takes to kickstart a quasar, but with those masses, you definitely don't want to be anywhere near for sure.
The Tao of math: The numbers you can count are not the real numbers.