Artist’s impression of a very distant quasar powered by a black hole with a mass two billion times that of the Sun. (Image: ESO/M. Kornmesser via Wikimedia Commons)

Scientists have found the largest known structure in the universe, a cluster of galactic cores so vast it would take four billion years for a spacecraft traveling at the speed of light to cross it.

The sighting challenges a theory from Einstein which suggests such a massive object shouldn’t exist in the universe.

A quasar is the compacted center of a galaxy surrounding a massive black hole from the early days of the universe.  Quasars  go through periods of extreme brightness which can last anywhere from 10 to 100 million years. They tend to band together in enormous clusters, or structures, forming large quasar groups (LQGs).

The international group of scientists led by Roger Clowes from the University of Central Lancashire’s Jeremiah Horrocks Institute, used data from the Sloan Digital Sky Survey (SDSS), a major surveying project that uses 2.5-m wide-angle optical telescope located at New Mexico’s Apache Point Observatory, to make their findings.

Clowes and his colleagues are astounded by the size of this structure, which defies the Cosmological Principal, based on Albert Einstein’s theory of General Relativity that assumes when you look at the universe from a sufficiently large scale; it looks the same no matter where you are observing it from.  The Cosmological Principle, according to the research team, is assumed but has never been demonstrated observationally ‘beyond reasonable doubt.’

Large quasar group (LQG) as imaged by the Big Throughput Camera at the Cerro Tololo Inter-American Observatory in Chile (Photo: Chris Haines)

“While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe,” said Clowes. “This is hugely exciting, not least because it runs counter to our current understanding of the universe. The universe doesn’t seem to be as uniform as we thought.”

Clusters of galaxies can be anywhere from six to 10 million light-years across, but the LQGs can be 650 million light-years or more across. Making calculations based on the Cosmological Principle, along with the modern theory of cosmology, astrophysicists shouldn’t be able to find a structure in the universe larger than 1.2 billion light-years, much less four billion light-years across as this newly sighted structure is.

To get some additional perspective of what the astronomers found, let’s step back and give it a sense of scale.  Our own galaxy, the Milky Way, is separated from its nearest neighbor, the Andromeda Galaxy, by a distance of 2.5 million light-years.

Clowes points out that his team’s discovery does have a typical dimension of 1.6 billion light-years. But, because it is elongated, its longest dimension is four billion light-years, making it about 1,650 times larger than the distance from the Milky Way to Andromeda.

An artist’s drawing shows a large black hole pulling gas away from a nearby star. (NASA)

Of all the celestial objects that make up the Universe, nothing is more mysterious than the black hole.

Now Denmark scientists have come up with what they say are groundbreaking theories that explain several properties of the enigmatic black hole.  The scientists’ research indicates black holes have properties similar to the dynamics of both solids and liquids.

Albert Einstein- circa 1921 (Photo: Creative Commons/Wikipedia)

What’s generally known about black holes is that they’re extremely compact  –some are as small as less than .01 mm– and that they can generate a gravitational pull so powerful that anything and everything that comes near them is swallowed up, including light.

We’re not able to see these cosmic vacuum cleaners because any light that does hit them is absorbed rather than being reflected. Black holes were predicted by Einstein’s general theory of relativity but scientists haven’t been able to determine their properties.

“Black holes are not completely black, because we know that they emit radiation and there are indications that the radiation is thermal, i.e. it has a temperature,” explains Niels Obers, a professor at the University of Copenhagen.

Obers says one can view black holes like particles. Since, in principle, a particle has no dimensions, it is merely a point. But, if a particle is given an extra dimension –such as a straight line– it then becomes a string.  And if you give the string yet an additional dimension, it becomes a plane. Physicists refer to one of these planes as a ‘brane’, similar to the biological term, ‘membrane’.

“In string theory, you can have different branes, including planes that behave like black holes, which we call black branes,” Obers says. “The black branes are thermal, that is to say, they have a temperature and are dynamical objects. When black branes are folded into multiple dimensions, they form a ‘blackfold’.”

Artist impression of black branes forming a “blackfold”(Artist impression by Merete Rasmussen)

Obers and his colleagues say they’ve been able to develop their new theories on the physics of black holes based on the principals of these black branes and blackfolds.

“The black branes are hydro-dynamic objects, that is to say that they have the properties of a liquid,” says Jay Armas, who also worked on the project. “We have now discovered that black branes also have properties which can be explained in terms of solids. They can behave like elastic material when we bend them.”

“With these new theories, we expect to be able to explain other black hole phenomena, and we expect to be able to better understand the physical properties of neutron stars,” said Obers.

Artist’s conception of black hole in globular cluster. (Image: Benjamin de Bivort; Strader, et al.; NRAO/AUI/NSF)

Astronomers recently made a surprising find while searching for a unique black hole in a tight cluster of stars 10,000 light years away from Earth.Instead of finding one black hole,  scientists with the National Radio Astronomy Observatory (NRAO) found two – twins – something that surprised them because, according to modern theory, there should only be one black hole in a cluster.

The discovery could make scientists reconsider their current understanding of the environment in globular star clusters.

The astronomers made the find while observing Messier 22 (M22), a globular star cluster containing hundreds of thousands of stars, with the Very Large Array (VLA) radio telescope located in New Mexico.  They were  searching for proof of a rare black hole known as an intermediate-mass black hole.

Unlike the supermassive black holes  found at the center of galaxies,  an intermediate-mass black hole has 10- to several tens of times more mass than the Sun, but is comparatively smaller in size.

“We didn’t find what we were looking for, but instead found something very surprising – two smaller black holes,” said Laura Chomiuk of Michigan State University and the National Radio Astronomy Observatory.

The globular cluster Messier 22 (M22) has been found to contain two black holes. (Image: Hunter Wilson)

Black holes are concentrations of mass  so dense that nothing, not even light, can escape them.  The NRAO astronomers think most black holes found within the globular cluster were  likely produced early in the cluster’s 12-billion-year history after massive stars exploded as supernovae.

Past scientific simulations suggest black holes fall toward the center of the cluster, beginning a violent gravitational competition with each other.  In the end,  only a single black hole remains in the cluster.

“There is supposed to be only one survivor possible,” said Jay Strader of Michigan State University and the Harvard-Smithsonian Center for Astrophysics. “Finding two black holes, instead of one in this globular cluster, definitely changes the picture.”One possible explanation is that the black holes may still be working to enlarge the center of the star cluster, reducing its density and slowing down the rate at which the black holes eject each other as they compete to become the cluster’s lone entity.

On the other hand, the astronomers think the reduction of the black hole’s density and ejection rate could also be due to the fact that the star cluster is not as far along in its process of contracting as previously thought.

The Very Large Array, a collection of 27 radio antennas, located in Socorro, New Mexico a component of the National Radio Astronomy Observatory (NRAO) (Photo: Wikimedia Commons/Creative Commons)

“Future VLA observations will help us learn about the ultimate fate of black holes in globular clusters,” Chomiuk said.

A paper on this finding was just published in the journal “Nature”

According the NARO, these twin black holes are also the first stellar-mass black holes to be found in any globular cluster in our Milky Way Galaxy. A stellar-mass black hole is formed by the collapse of a star that has a mass that is generally 10 to 24 times that of the Sun, as compared to the giant “supermassive” black holes, which are millions, if not billions, of times as massive as the Sun.

Astronomers believe supermassive black holes lie at the center of virtually all large galaxies, including ours.