Pulsing light may indicate supermassive black hole merger

supermassive black hole
An artist's depiction of the accretion of a thick ring of dust into a supermassive black hole. The accretion produces jets of gamma rays and X-rays. Credit: ESA / V. Beckmann (NASA-GSFC)

As two galaxies enter the final stages of merging, scientists have theorized that the galaxies' supermassive black holes will form a "binary," or two black holes in such close orbit they are gravitationally bound to one another. In a new study, astronomers at the University of Maryland present direct evidence of a pulsing quasar, which may substantiate the existence of black hole binaries.

"We believe we have observed two supermassive black holes in closer proximity than ever before," said Suvi Gezari, assistant professor of astronomy at the University of Maryland and a co-author of the study. "This pair of black holes may be so close together that they are emitting gravitational waves, which were predicted by Einstein's theory of general relativity."

The study was published online April 14, 2015, in the Astrophysical Journal Letters. The discovery could shed light on how often black holes get close enough to form a gravitationally bound binary and eventually merge together.

Black holes typically gobble up matter, which accelerates and heats up, emitting electromagnetic energy and creating some of the most luminous beacons in the sky called quasars. When two black holes orbit as a binary, they absorb matter cyclically, leading theorists to predict that the binary's quasar would respond by periodically brightening and dimming.

The researchers conducted a systematic search for so-called variable quasars using the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1) Medium Deep Survey. This Haleakala, Hawaii-based telescope imaged the same patch of sky once every three days and collected hundreds of data points for each object over four years.

In that data, the astronomers found quasar PSO J334.2028+01.4075, which has a very large black hole of almost 10 billion solar masses and emits a periodic optical signal that repeats every 542 days. The quasar's signal was unusual because the light curves of most quasars are arrhythmic. To verify their finding, the research team performed rigorous calculations and simulations and examined additional data, including photometric data from the Catalina Real-Time Transient Survey and spectroscopic data from the FIRST Bright Quasar Survey.

"The discovery of a compact binary candidate system like PSO J334.2028+01.4075, which appears to be at such close orbital separation, adds to our limited knowledge of the end stages of the merger between supermassive black holes," said UMD astronomy graduate student Tingting Liu, the paper's first author.

The researchers plan to continue searching for new variable quasars. Beginning in 2023, their search could be aided by the Large Synoptic Survey Telescope, which is expected to survey a much larger area and could potentially pinpoint the locations of thousands of these merging supermassive black holes in the night sky.

"These telescopes allow us to watch a movie of how these systems evolve," said Liu. "What's really cool is that we may be able to watch the orbital separation of these supermassive get smaller and smaller until they merge."


Explore further

Could the Milky Way become a quasar?

More information: The research paper, "A Periodically Varying Luminous Quasar at z = 2 from the Pan-STARRS1 Medium Deep Survey: A Candidate Supermassive Black Hole Binary in the Gravitational Wave-driven Regime," Tingting Liu, Suvi Gezari, Sebastien Heinis, Eugene A. Magnier, William S. Burgett, Kenneth Chambers, Heather Flewelling, Mark Huber, Klaus W. Hodapp, Nicholas Kaiser, Rolf-Peter Kudritzki, John L. Tonry, Richard J. Wainscoat, and Christopher Waters, was published online April 14, 2015, in the Astrophysical Journal Letters, dx.doi.org/10.1088/2041-8205/803/2/L16
Journal information: Astrophysical Journal Letters

Citation: Pulsing light may indicate supermassive black hole merger (2015, April 20) retrieved 21 May 2019 from https://phys.org/news/2015-04-pulsing-supermassive-black-hole-merger.html
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Apr 20, 2015
Hopefully they get aLIGO up and running soon and can look for signs of the potential gravity waves from this event. It would be interesting to know, using mass and orbital data for the black holes, the period given above (542 days), and doing calculations using the simulation detailed here: http://phys.org/n...les.html whether the gravitational wave signal would theoretically be strong enough for aLIGO to detect, and even more interesting, once aLIGO is up and running, to see if it does indeed detect the waves (assuming they're strong enough to get above background).

Apr 20, 2015
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Apr 20, 2015
Gravitational waves (and their propagation) are a prediction of General Relativity. You appear, docile, to be denying GR.

Apr 20, 2015
Hi Da Schneib (and docile). Still,very busy; can't stay long. However...

Da Schneib, I would be very interested to read your/others' response to docile's point re the maths/abstract analytical "space-time" construct already including the 'time' component, and as such, any 'treatment' utilizing this construct (SR/GR for example) already describes 'world lines' for any chosen object's observed/predicted 'motional history'.

The logical upshot of such would be that 'motion' FOR any 'space-time' entity such as GR's predicted but not observed 'gravitational wave' is already fully incorporated in our physical/abstract observation/analysis space-time based 'construct'; and hence no further 'motion' degrees of freedom is available for a 'gravitational wave entity' to 'effect/propagate' by within that analytical construct.

Will look in again later. Thanks in advance.

Apr 21, 2015
You appear, docile, to be denying GR.

Zeph always has. No surprise there.

Apr 21, 2015
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Apr 21, 2015
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Apr 21, 2015
1) So, how close to each other?
2) Please, please use a different verb than "gobble" when discussing black holes. Another article used "feasts on" which isn't much better, but at least it's a (small) step back.

Apr 21, 2015
Why artist depiction? Why not rendering from a 3-D physics model?

Apr 21, 2015
It would be interesting to know, ... whether the gravitational wave signal would theoretically be strong enough for aLIGO to detect,
Sensitivity of LIGO's 6th science run (S6) for neutron star binaries was to about 160 million light years away, and for black hole binaries it was about 620 million light years.

From the letter's abstract, "PSO J334.2028+01.4075 is a luminous radio-loud quasar at z = 2.060."

If distance, d = z c / H_0,
with z = 2.06, H_0 = 70.8 km/s/Mpc, and c = 299792 m/s,
Then
d = (2.06)(299792 m/s) / (70.8 km/s/Mpc)
≈ 8.72276158 Mpc
≈ 2.68 million ly

"Meanwhile the L1 detector at LIGO Livingston continues to progress, currently performing with an in-commissioning estimated sensing range of 60 Megaparsecs (nearly 200 million light years) for a signal from a neutron star inspiral..." -- see https://www.advan...mit.edu/

Apr 21, 2015
Late edit-
Oops c is 299792458 m/s, so
d = 2.06(299792458 m/s) / (70.8 km/s/Mpc)
= 8722.7749 Mpc = 2675.69782 Mly ≈ 2.7 billion ly
Sorry, duh. I hope that's about right :)

Apr 21, 2015
Here it is:
" ... the Advanced LIGO detectors will be able to see inspiraling binaries made up of two 1.4 M neutron stars to a distance of 300 Mpc, some 15x further than the initial LIGO, and giving an event rate some 3000x greater. Neutron star - black hole (BH) binaries will be visible to 650 Mpc; and coalescing BH+BH systems will be visible to cosmological distance, to z=0.4." ( from https://www.advan...ary.html )

So it looks like PSO J334.2028+01.4075 is a tad too far away for aLIGO.

Apr 21, 2015
Gravitational waves (and their propagation) are a prediction of General Relativity. You appear, docile, to be denying GR
On the contrary, the absence of gravitational waves (propagation) is the direct consequence of GR
BS. Link and quote please.

You're denying GR. GR predicts gravity waves. Now stop lying. You get one more chance then you go on ignore; I ain't dealing with any more anti-relativity cranks.

ETA: Oh, it's Zeph again? I'll give him one shot.

Apr 21, 2015
Thanks Protoplasmix. U rok.

Quick question: what power does gravity radiation increase at with mass? I think the range estimates are based on an approximately solar-mass pair of neutron stars, isn't that what M means, one solar mass?

Apr 25, 2015
Quick question: what power does gravity radiation increase at with mass?
Good question, I'm not sure there's a quick answer* -- for any given mass** the strength of the signal increases with time for a binary system, as the waveform is a "chirp".

* proportional to system mass raised to some fraction less than 5/6th? If it's been worked out exactly, I couldn't find it.

** the equations include higher order post Newtonian terms, each term has the 'chirp mass' with a fractional exponent (<1), where
M_system = m1 + m2
M_reduced = ( m1m2 ) / M_system
M_chirp = ( M_reduced^(3/5) ) · ( M_system^(2/5) )
See equations 7 and 8 in this note -- http://arxiv.org/abs/1203.2674 and note the slopes of the curves in Fig. 2.
I think the range estimates are based on an approximately solar-mass pair of neutron stars, isn't that what M means, one solar mass?
The M with a dotted circle subscript is solar mass. The value used for neutron stars is usually 1.4 M_solar.

Apr 25, 2015
1.4 M_solar Of course; Chandrasekhar's limit is 1.2 M☉.

Thanks again, Protoplasmix!

Apr 26, 2015
I finally had time to play with this, and it confirms my suspicion that inspiraling SMBHs could be detected at greater range, but their frequencies would be much lower; it's not out of order to suggest that they could be on the order of the frequency expected here. Unfortunately because of the structures of the gravitational observatories, and the frequency of data gathering, it's unlikely that either observatory (LIGO or Virgo) could detect such inspiraling SMBHs without data processing that's far beyond anything we currently have. Also, since SMBHs are quite rare spatially speaking compared to inspiraling ordinary stellar BHs and neutron stars, it's unlikely that any will occur any time soon (like in the next million years or so, heh) within range of these detectors, even though that range would be far greater than the range for lower mass objects. Putting these together, it's probably a waste of time to try to detect them with these observatories.

Thanks yet again, Proto!

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