Did gravitational wave detector find dark matter?

LIGO
An aerial view of the Laser Interferometer Gravitational-wave Observatory (LIGO) detector in Livingston, Louisiana. LIGO has two detectors: one in Livingston and the other in Hanaford, Washington. LIGO is funded by NSF; Caltech and MIT conceived, built and operate the laboratories. Credit: LIGO Laboratory

When an astronomical observatory detected two black holes colliding in deep space, scientists celebrated confirmation of Einstein's prediction of gravitational waves. A team of astrophysicists wondered something else: Had the experiment found the "dark matter" that makes up most of the mass of the universe?

The eight scientists from the Johns Hopkins Henry A. Rowland Department of Physics and Astronomy had already started making calculations when the discovery by the Laser Interferometer Gravitational-Wave Observatory (LIGO) was announced in February. Their results, published recently in Physical Review Letters, unfold as a hypothesis suggesting a solution for an abiding mystery in astrophysics.

"We consider the possibility that the black hole binary detected by LIGO may be a signature of dark matter," wrote the scientists in their summary, referring to the black hole pair as a "binary." What follows are five pages of annotated mathematical equations showing how the researchers considered the mass of the two objects LIGO detected as a point of departure, suggesting that these objects could be part of the mysterious substance known to make up about 85 percent of the mass of the universe.

A matter of scientific speculation since the 1930s, dark matter has recently been studied with greater precision; more evidence has emerged since the 1970s, albeit always indirectly. While dark matter itself cannot yet be detected, its gravitational effects can be. For example, the influence of nearby dark matter is believed to explain inconsistencies in the rotation of visible matter in galaxies.

The Johns Hopkins team, led by postdoctoral fellow Simeon Bird, was struck by the mass of the detected by LIGO, an observatory that consists of two expansive L-shaped detection systems anchored to the ground. One is in Louisiana and the other in Washington State.

Black hole masses are measured in terms of multiples of our sun. The colliding objects that generated the gravity wave detected by LIGO - a joint project of the California Institute of Technology and the Massachusetts Institute of Technology - were 36 and 29 solar masses. Those are too large to fit predictions of the size of most stellar black holes, the ultra-dense structures that form when stars collapse. But they are also too small to fit predictions for the size of at the center of galaxies.

The two LIGO-detected objects do, however, fit within the expected range of mass of "primordial" black holes.

Primordial black holes are believed to have formed not from stars but from the collapse of large expanses of gas during the birth of the universe. While their existence has not been established with certainty, primordial black holes have in the past been suggested as a possible solution to the dark matter mystery. Because there's so little evidence of them, though, the "dark matter is primordial black holes" hypothesis has not gained a large following among scientists.

The LIGO findings, however, raise the prospect anew, especially as the objects detected in that experiment conform to the mass predicted for dark matter. Predictions made by scientists in the past held that conditions at the birth of the universe would have produced lots of these primordial black holes distributed roughly evenly in the universe, clustering in halos around galaxies. All this would make them good candidates for dark matter.

The Johns Hopkins team calculated how often these would form binary pairs, and eventually collide. Taking into account the size and elongated shape believed to characterize primordial black hole binary orbits, the team came up with a collision rate that conforms to the LIGO findings.

"We are not proposing this is the dark matter," said one of the authors, Marc Kamionkowski, the William R. Kenan Jr. Professor in the Department of Physics and Astronomy. "We're not going to bet the house. It's a plausibility argument."

More observations from LIGO and other evidence would be needed to support the hypothesis, including further detections like the one announced in February. That could suggest greater abundance of objects of that signature mass.

"If you have a lot of 30-mass events, that begs an explanation," said co-author Ely D. Kovetz, a postdoctoral fellow in physics and astronomy at Johns Hopkins. "That the discovery of gravitational waves could be connected to " is creating lots of excitement among astrophysicists, he said.

"It's got a lot of potential," Kamionkowski said.


Explore further

Scientist suggests possible link between primordial black holes and dark matter

More information: Simeon Bird et al, Did LIGO Detect Dark Matter?, Physical Review Letters (2016). DOI: 10.1103/PhysRevLett.116.201301
Journal information: Physical Review Letters

Citation: Did gravitational wave detector find dark matter? (2016, June 15) retrieved 22 July 2019 from https://phys.org/news/2016-06-gravitational-detector-dark.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
2197 shares

Feedback to editors

User comments

Jun 15, 2016
They might consider a mass made of quantum plasma of positrons and electrons in magnetic compression of their opposite charges , made from taking neutrons and protons apart in high velocity kinetic collisions the magnetic part of mass production in their mathematical equations

Jun 15, 2016
Singularity in charged particles is an assumption based on the measurement of charge thru instrumentation, which would the particles existence outside of the laws of magnetics, on the quantum chart ,the classification of particles are positive, negative, and neutral , neutral should give you a clue of those constructions, because that means those quantum parts have equal charges and can't measure the dominant charge, thus classified as no charge , the positive quantum particles are positive dominant and negative minor quantum mass, the negative quantum particles are opposite ,negative dominant with a minor positive quantum mass ,

Jun 15, 2016
Meh. Had a conversation with someone who knows a fair bit of cosmology on here about this a while back and the upshot was, there are some fairly serious astrophysical evidence problems with the missing mass being black holes. If I get bored later I might go find the conversation.

Jun 15, 2016
All charged particles are balanced charges or unbalanced charges

Jun 15, 2016
36 and 29 solar mass objects locked into a high velocity kinetic collision will not produce an object of 65 solar mass's, it will lose 21.66 solar mass's in that that construction thrown out of that violent collisions in coalescing a new mass those charges particles has a good probability of being the signal you detected , of those particles riding magnetic waves out the area in particle plasma waves

Jun 16, 2016
Ursiny, with the Pauli Exclusion Principle, extended, you find that no to particles of Any sort can hold the exact same charge as another of it's kind, even true for so-called 'Neutrons' considered neutral but do not have an actual 'pure' neutral state. It could easily be this slight differentiation in microcharges that create what we see as 'Gravity'. That would account for how 'weak' gravity seems to be. Thus we can find that in the end, gravity is the charge differential across the same particle types, none being equal, thus we have some level of attraction even if the charges appear to be very nearly the same. We find that at a certain energy level, when reached, and electron releases a photon, but by what mechanisms did the electron gain those quanta, surely smaller than it takes to make an electron change orbits. Seeing as how energy levels are never the same, and matter and photons permeate space, does this mean they are in constant change thus 'transmitting' gravity?

Jun 16, 2016
This comment has been removed by a moderator.

Jun 16, 2016
This comment has been removed by a moderator.

Jun 16, 2016
Epoxy how many mini galaxies are in the milky way orbiting on its perimeter 400 hundred or Andromeda 1000 now if the CCM was a quantum plasma of positrons and electrons ,and its growth of mass was from an orbiting high velocity plasma field made from taking apart neutrons and protons in high velocity kinetic collisions turning them into positrons and electrons raining out of that orbiting kinetic storm , and those neutrons and protons were produce from all the atoms approaching that mass having their orbiting electrons stripped off them before the storm , being suspended in orbit around that mass by gravity constructing a magnetic orbiting magnetic negatively charged field vessel around that mass like build a cosmic particle accelerator,

Jun 16, 2016
That mechanical concept of the galaxy would mean that after that plasma storm disappears from zero material to feed it in the CCM central core area overtime the CCM would cool off and the orbiting negatively charged field vessel would have a much closer orbit to the mass , that's when that negatively charged rotating induction environment could magnetically and mechanically turn that positron and electron mass back into neutrons reducing that CCM and its gravity in mass to release all those orbiting mini galaxies on its perimeter orbiting out away from the galaxy in galaxy expansion, and those are the seeds of creation

Jun 16, 2016
We are talking about black holes with a "radius" of about 90 km. I'm not sure that they would be significant sources of X-rays or other radiation from an accretion disk. Hence, dark...
Not to mention this pair was a billion light years away or so. A 90km BH with, say, a ten million km accretion disk (that's probably exaggerating a lot) isn't exactly going to stand out; we can't resolve stars from that far away unless they're supernovae.

Jun 16, 2016
I would not need something to build new galaxies ,because every galaxy is building baby galaxies all they need is birthed

Jun 16, 2016
We are talking about black holes with a "radius" of about 90 km. I'm not sure that they would be significant sources of X-rays or other radiation from an accretion disk. Hence, dark...
Not to mention this pair was a billion light years away or so. A 90km BH with, say, a ten million km accretion disk (that's probably exaggerating a lot) isn't exactly going to stand out; we can't resolve stars from that far away unless they're supernovae.

Would they even have that much of accretion disk? Another article leads me to understand that many BH binaries are actually resident outside of dense star populations. Therefore, leading me to think there's not a lot of stuff to accrete, anyway. Any matter in the vicinity would be pulled in pretty fast, but in insufficient volume to actually allow creation of any GRBs...

Jun 16, 2016
I was looking to establish a maximum reasonable size, @Whyde. Since the current data favors a pair of BHs that were kicked out of a globular cluster, it's most likely they were in the halo and had almost no accretion disks at all.

Jun 16, 2016
I was looking to establish a maximum reasonable size, @Whyde. Since the current data favors a pair of BHs that were kicked out of a globular cluster, it's most likely they were in the halo and had almost no accretion disks at all.

I'm curious - with little accretive material available and very little gravitational disturbance, how long would they last?

Jun 16, 2016
Well, Hawking radiation is weak enough that stellar mass BHs postulated to have been formed during the Big Bang would be expected to still be around today, 13 billion years later. I'd say a very, very long time, on the order of trillions of years.

Jun 16, 2016
Well, Hawking radiation is weak enough that stellar mass BHs postulated to have been formed during the Big Bang would be expected to still be around today, 13 billion years later. I'd say a very, very long time, on the order of trillions of years.

Hence, the reason they're called primordial... I got it.
So.. they would prob'ly be the LAST thing to dissipate in an expanding universe, that far down the road...
Hmmm... I wonder if this might be a sort of "Great Attractor" phenomenon...

Jun 17, 2016
This comment has been removed by a moderator.

Jun 17, 2016
This comment has been removed by a moderator.

Jun 17, 2016
This comment has been removed by a moderator.

Jun 17, 2016
Just as an aside, if the recent discovery strengthens the idea of primordial BHs, then there would never have been a cosmological 'dark age' at any time in the past. The size-distribution of micro- nano- pico- and femto- BHs in the early years and millennia would mean innumerable evaporating BHs disappearing in a burst of Hawking radiation all the time.

The universe, then, would have appeared to be populated with tiny flashes of light, some bright and near, some far, in all directions, but mostly in the x-ray and gamma range. At this time only the larger of the BH's remain, adding mass to galaxies, but being otherwise virtually indetectible.

Jun 20, 2016
I keep wondering why we are going round and round about the same subject flailing it to death (I hope). I think that bh are magnetic mazes. Mazed light if you will. If there is a ex-solar object that our solar system has approached in the past that produces a duplicate shadow system in the sky without the gravitational effects on Earth, would it not have to be a magnetic refraction?
The ancient Egyptians studied Algol, a double/triple star system. Giza is aligned with Sirius, a double/triple star system and our closest neighbor is Centauri A&B with Proxima makes a triple system. Galactic magnetic fields produce refractions which science has mistaken for gravitational lensing enabling this mistaken belief in gravity waves which are magnetic 'burps' or collapses from a maze of light.

Jun 20, 2016
So.. they would prob'ly be the LAST thing to dissipate in an expanding universe, that far down the road...

Very small BHs dissipate rather fast. Note that 'small' in this case means 'much less than a solar mass'.
A very small BH with 100 billion tonnes of mass would decay within roughly 2.5 bn years.
The larger these things get the (disproportionally) longer lived they are. The way I think it works is that the stronger the gravitational gradient at the event horizon the stronger the Hawking radiation. Large black holes have a very 'shallow' gradient at the event horizon
E.g. a solar mass black hole would be around for 60 million trillion trillion trillion trillion trillion years (about 33 orders of magnitude longer than the likely half life of a proton)

Current black holes don't disspiate because they get more input from the CMBR than they put out Hawking radiation. Only after that has cooled a lot more (i.e. the universe expanded) will they start dissipating.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more