Fascinating rhythm: Light pulses illuminate a rare black hole

August 17, 2014
This image of the galaxy Messier 82 is a composite of data from the Chandra X-Ray Observatory, the Hubble Space Telescope and the Spitzer Space Telescope. The intermediate-mass black hole M82 X-1 is the brightest object in the inset, at approximately 2 o'clock near the galaxy's center. Credit: NASA/H. Feng et al.

The universe has so many black holes that it's impossible to count them all. There may be 100 million of these intriguing astral objects in our galaxy alone. Nearly all black holes fall into one of two classes: big, and colossal. Astronomers know that black holes ranging from about 10 times to 100 times the mass of our sun are the remnants of dying stars, and that supermassive black holes, more than a million times the mass of the sun, inhabit the centers of most galaxies.

But scattered across the universe like oases in a desert are a few apparent of a more mysterious type. Ranging from a hundred times to a few hundred thousand times the sun's mass, these intermediate-mass black holes are so hard to measure that even their existence is sometimes disputed. Little is known about how they form. And some question whether they behave like other black holes.

Now a team of astronomers has accurately measured—and thus confirmed the existence of—a black hole about 400 times the mass of our sun in a galaxy 12 million light years from Earth. The finding, by University of Maryland astronomy graduate student Dheeraj Pasham and two colleagues, was published online August 17 in the journal Nature.

Co-author Richard Mushotzky, a UMD astronomy professor, says the black hole in question is a just-right-sized version of this class of astral objects.

"Objects in this range are the least expected of all black holes," says Mushotzky. "Astronomers have been asking, do these objects exist or do they not exist? What are their properties? Until now we have not had the data to answer these questions." While the intermediate-mass black hole that the team studied is not the first one measured, it is the first one so precisely measured, Mushotzky says, "establishing it as a compelling example of this class of black holes."

A black hole is a region in space containing a mass so dense that not even light can escape its gravity. Black holes are invisible, but astronomers can find them by tracking their gravitational pull on other objects. Matter being pulled into a black hole gathers around it like storm debris circling a tornado's center. As this cosmic stuff rubs together it produces friction and light, making black holes among the universe's brightest objects.

Since the 1970s astronomers have observed a few hundred objects that they thought were intermediate-mass black holes. But they couldn't measure their mass, so they couldn't be certain. "For reasons that are very hard to understand, these objects have resisted standard measurement techniques," says Mushotzky.

Pasham, who will receive his Ph.D. in astronomy at UMD August 22, focused on one object in Messier 82, a galaxy in the constellation Ursa Major. Messier 82 is our closest "starburst galaxy," where young stars are forming. Beginning in 1999 a NASA satellite telescope, the Chandra X-ray Observatory, detected X-rays in Messier 82 from a bright object prosaically dubbed M82 X-1. Astronomers, including Mushotzky and co-author Tod Strohmayer of NASA's Goddard Space Flight Center, suspected for about a decade that the object was an intermediate-mass black hole, but estimates of its mass were not definitive enough to confirm that.

Between 2004 and 2010 NASA's Rossi X-Ray Timing Explorer (RXTE) satellite telescope observed M82 X-1 about 800 times, recording individual x-ray particles emitted by the object. Pasham mapped the intensity and wavelength of x-rays in each sequence, then stitched the sequences together and analyzed the result.

Among the material circling the suspected black hole, he spotted two repeating flares of light. The flares showed a rhythmic pattern of light pulses, one occurring 5.1 times per second and the other 3.3 times per second – or a ratio of 3:2.

The two light oscillations were like two dust motes stuck in the grooves of a vinyl record spinning on a turntable, says Mushotzky. If the oscillations were musical beats, they would produce a specific syncopated rhythm. Think of a Latin-inflected bossa nova, or a tune from The Beatles' Abbey Road:

"Mean Mister Mustard sleeps in the park, shaves in the dark, try'na save paper."

In music, this is a 3:2 beat. Astronomers can use a 3:2 oscillation of light to measure a black hole's mass. The technique has been used on smaller black holes, but it has never before been applied to intermediate-mass black holes.

Pasham used the oscillations to estimate that M82 X-1 is 428 times the mass of the sun, give or take 105 solar masses. He does not propose an explanation for how this class of black holes formed. "We needed to confirm their existence observationally first," he says. "Now the theorists can get to work."

Though the Rossi telescope is no longer operational, NASA plans to launch a new X-ray telescope, the Neutron Star Interior Composition Explorer (NICER), in about two years. Pasham, who will begin a post-doctoral research position at NASA Goddard in late August, has identified six potential intermediate-mass black holes that NICER might explore.

This work is based on observations made with the Rossi X-ray Timing Explorer (RXTE), managed and controlled by NASA's Goddard Space Flight Center in Greenbelt, Md. The content of this article does not necessarily reflect the views of NASA or Goddard Space Flight Center.

Explore further: How much of the universe is black holes?

More information: "A 400 solar mass black hole in the M82 galaxy," Dheeraj R. Pasham, Tod E. Strohmayer, Richard F. Mushotzky, was published online Aug. 17, 2014 in Nature. dx.doi.org/10.1038/nature13710

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1 / 5 (1) Aug 17, 2014
"He does not propose an explanation for how this class of black holes formed."

Ever considered that hundreds-solar-mass black holes grow out of tens-solar-mass ones? Basically, they are obese, eat much, quickly are in millions, so hundreds-solar-mass are hard to find.
1 / 5 (3) Aug 17, 2014
The number of theories, in which black holes can radiate their matter into outside is growing in recent time. We should realize, that whereas the general relativity predicts, everything should end inside of singularity with no mercy, the quantum mechanics has quite opposite opinion in this matter and it does predict, every quantum packet of free particle should expand into infinity fast. And these two theories differ in some 108 orders of magnitude in this prediction - so that every introduction of quantum mechanics into black hole physics would violate the general relativity models a lot. Before some time Hawking was first who started with it and he predicted, that the black holes will end with explosion. At the end of 70's astronomer LaViolette predicted, that the black hole at the center of Milky Way suffer with periodical eruptions and now we have quite small black hole, which changes its brightness periodically. Apparently the model of black holes converges to common stars fast.
1 / 5 (3) Aug 17, 2014
Just the fact, the observed black hole is lightweight (some 400 solar masses) indicates, it's black hole character will be only poorly expressed and such a black hole would behave like any other dense star, which suffers with periodical eruptions - in form of polar jets. The extreme strong gravitational darkening at the equatorial plane would prohibit such a dense star to radiate across its whole surface. Such a behavior could explain too, why the black holes of the intermediate size are so rare - they're gravitationally unstable in fact and they tend to evaporate into smaller but more dense remnants - possibly under gigantic explosion at the end of such transform. In classical Hawking model the black holes should explode when they achieve a quite microscopic size. Therefore the Hawking's model is not completely wrong - it just applies to larger scales, than the scientists expected.
Aug 17, 2014
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Bob Osaka
5 / 5 (1) Aug 18, 2014
Harmonic and overtone physics combined with an intermediate black hole, thank you M82 X-1.
Not much has been said about the spin of black holes or of the massive magnetic fields which they surely must generate. The 5.1 second and 3.3 second flares could be the result of an off axis wobble revealing both the northern and southern poles. The ratio of 3:2 including nodes and antinodes may actually be half the spin rate. The flares may be matter interacting with M82 X-1's magnetic field analogous to an aurora effect and not the black hole itself.
Aug 18, 2014
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1 / 5 (3) Aug 18, 2014
M82 X-1 is not at the centre of its galaxy. Astronomers have suggested that one way in which this black hole could have grown to such an abnormal size is thanks to a cluster of stars near its location, which could have fed the object, before a massive star's approach ejected the black hole from the cluster.
This could also point to up-down dark matter driven model of galaxy formation (time reversed accretion), in which large black holes were formed with coalescing of many others, smaller ones like the settling oil inside of lava lamp - and the intermediate size black hole found could be remnant of one of them.
1.7 / 5 (6) Aug 20, 2014
I don't believe in black holes. I don't believe in neutron stars either. I don't buy any of it.
I am totally unconvinced and generally skip these topics in my readings.
1 / 5 (3) Aug 20, 2014
sub: Where is Science ?
M82 X-1, which is the brightest X-ray source in a galaxy known as Messier 82
Why can"t one get rid of Blck-hole psychology and observe phenomena as it is ?
Where is Science here except super-imposition of psychology to mislead ?
Aug 20, 2014
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