Indeed, in the creation of the heavens and the earth and the alternation of the night and the day are signs for those of understanding. (‘Ali Imran 3:190).
Black holes are the only objects in the universe with a gravitational pull so strong that even light can’t escape. While they trap everything behind their event horizon, black holes seem mysteriously to be an infinite source of intrigue and news stories as well.
A series of interesting scientific finds about them added an extra force even stealing some of the spotlights from the long-awaited Higgs boson discovery at the LHC. Here is a roundup of the biggest black hole discoveries that are changing the way astrophysicists are viewing the universe’s most powerful gravity sources.
Astronomers find bigger black holes every year. Telescopes images seem to defy all theoretical limits on the mass of black holes. In 2013, a study pointed that black holes with masses as large as 40 billion times the mass of the sun are not a novelty.
During a survey of 18 galaxy clusters, Chandra’s X-ray Observatory detected enormous outbursts of energy from ten of the brightest galaxies. The final results pointed that these ten black holes have masses between 10 and 40 billion times the mass of the sun. Compared to the black hole at the center of our home Milky Way, at 4 million solar masses in Sgr A*, these monstrous black holes have earned their new name as “Ultramassive.”
“Our results show that there may be many more ultramassive black holes in the universe than previously thought,” said study leader Julie Hlavacek-Larrondo of Stanford University and formerly of Cambridge University in the UK.
The mass of such ultramassive black holes is more than a novelty number. As their mass is about twenty percent of the mass of their galaxies, they affect the galaxy evolution in ways that astronomers are only beginning to consider.
In another study, astronomers at Max Planck Institute for Astronomy have discovered another 17 billion solar masses black hole that could shake the foundations of current models of galaxy evolution. The team led by Remco van den Bosch captured astronomical data for NGC 1277 which weighs in at an extraordinary 14% of the total galaxy mass.
Black Hole Expelled
In one of a kind observation, Chandra X-ray Observatory gave us an image of a massive black hole very likely in the process of getting kicked out from its host galaxy.
In the CID-42 galaxy which is located about 4 billion light years from Earth, the study suggest that the center black hole collided with another black hole, recoiled from the collision gravitational radiation, and is leaving its host galaxy at a speed of few million miles per hour.
“It’s hard to believe that a supermassive black hole weighing millions of times the mass of the sun could be moved at all, let alone kicked out of a galaxy at enormous speed,” said Francesca Civano of the Harvard-Smithsonian Center for Astrophysics (CfA), who led the new study. “But these new data support the idea that gravitational waves — ripples in the fabric of space first predicted by Albert Einstein but never detected directly — can exert an extremely powerful force.”
The study suggests that the recoil force the black hole experienced arises because more gravitational waves are being emitted in one direction than another. This scenario is consistent with recent computer simulations of two black holes merging. While this phenomenon is likely to be rare, it nevertheless could mean that there are many giant black holes roaming undetected out in the vast spaces between galaxies.
“These black holes would be invisible to us,” said co-author Laura Blecha, also of CfA, “because they have consumed all of the gas surrounding them after being thrown out of their home galaxy.”
Supermassive black holes at the center of a galaxy feed on the surrounding stellar matter and releases huge amounts of energy in the form of high energy particles and jets of X-rays. The host galaxies of such black holes are also known as quasars. In 2014, astronomers discovered the biggest jet and the oldest one.
The Australia Telescope Compact Array captured an image of PKS 0637-752 an extragalactic jet extending more than 2 million light-years. This length makes it about ten times longer than our entire Milky Way galaxy.
“Massive jets like this one have been studied for decades, since the beginning of radio astronomy, but we still don’t understand exactly how they are produced or what they’re made of,” said Leith Godfrey of the International Centre for Radio Astronomy Research in Australia.
The team was surprised at the amount of X-rays the quasar emits as current models can’t quite explain what the astronomers saw.
In another find, Chandra X-ray Observatory detected a jet of X-rays from a supermassive black hole 12.4 billion light years from Earth. Being the oldest and most distant X-ray jet ever observed, quasar GB 1428+4217 gives astronomers a glimpse into the activity of supermassive black holes in the early universe.
“We’re excited about this result not just because it’s a record holder, but because very few X-ray jets are known in the early universe,” said Teddy Cheung of the National Academy of Sciences.
Slightly after the Big Bang incident, the universe was full of high energy photons otherwise known as cosmic background radiation. The early universe is an interesting place with the cosmic background radiation being a thousand times more energetic than it is now. As the quasar is observed when the universe is at the young age of about 1.3 billion years, it interacts with the energetic background radiation this makes the jet much brighter.
The scientists estimate the length of the jet at 230,000 light years, a little more than twice the diameter of the entire Milky Way galaxy. This jet is only seen on one side of the quasar which implies that the jet is pointed almost directly toward us.
Most Powerful Blast
The telescopes of the European Southern Observatory in Chile have detected the most powerful energy outflow from a supermassive black hole at the center of quasar galaxy SDSS J1106+1939.
“We discovered the most energetic quasar outflow ever seen, at least five times more powerful than any that have been observed to date,” said Nahum Arav, astronomer at Virginia Tech and co-author of the study.
At a distance of 11.5 billion light-years away, the quasar ejects out gas and dust as much as 400 times the weight of our sun every year at velocities of roughly 29 million kilometers per hour.
With mass of one to three billion suns, the supermassive black hole outputs more than hundred times the power our whole Milky Way galaxy does.
“I believe this is the smoking gun for several theoretical ideas that use the mechanical energy output of quasars to solve several important problems in the formation of galaxies and cluster of galaxies,” said Arav.
Both the mass and power output of supermassive black holes no doubt affect galaxy evolution. Quasars will play an important role in putting all the pieces together to understand how galaxies evolved from the early universe to be what they see today.
Paradox or Firewalls
While observations seem to flow with new information about black holes, a group of theorists have stopped to question one of their most unobjectionable, taken for granted properties. In short, a controversial paper puts forward a paradox and the way out they propose is to add a firewall entrance to black holes.
One fact about black holes is quite well-known: black holes have what we call “Event Horizon”, and nothing not even light can escape once it enters this point of no-return. Another quantum fact about black holes is that they evaporate after a while because they emit energy in the form of (Hawking Radiation). Also, more massive bigger black holes take more time to evaporate.
The puzzling paper published by four researchers from the Kavli Institute for Theoretical Physics in University of California found a clash between the three major assumptions about black holes’ dynamics.
The first assumption comes from the equivalence principle in Albert Einstein’s general relativity. Its tells us that nothing or no one entering a black hole will notice anything unusual when passing the event horizon; this is the so-called No Drama assumption.
The second postulate was the focus of heated debate the past two decades but finally proven correct. The unitarity principle, based on the quantum mechanics of black holes, tells us that information falling into a black hole is not lost forever. It comes back in one form or another as the black hole evaporates.
The third and last major principle is the simple statement that physics works as expected far away from a black hole but it may break down at some point within it (either at its center or at its event horizon). No new physics is to be expected in black holes.
The proposed paradox shows that given that all three assumptions are correct, one may perfectly duplicate a quantum state, and this is not permissible according to the No Cloning theorem, one of the fundamental results of quantum physics. The paper proposes that the No Drama assumption has to be modified in order to avoid this dilemma.
“Perhaps the most conservative resolution is that the infalling observer burns at the horizon,” the paper reads.
As arguments continue about whether the event horizon of black holes is a firewall or not, it’s not clear how the debate will end. But either way, something fundamental about the way we think of black holes is about to change.
This article was first published in 2014 and is currently republished for its importance.