X-ray Images of Earliest Galaxies Reveals Infant Black Holes in Existence --What Ultimately is Their Function?
Completing the deepest X-ray images ever made, NASA's Chandra X-Ray Observatory has detected numerous massive black holes lurking in the dusty hearts of galaxies that formed within a billion years of the big bang birth of the cosmos, astronomers announced Wednesday. The observations are the first direct evidence showing massive black holes were common in the early universe, growing in concert with their host galaxies much more rapidly than previously thought.
"They may also merge with black holes from other galaxies as their hosts merge and they may end up accumulating a hundred or even a thousand times the mass that they have in the early universe until they end up at the centers of nearby galaxies."
Unlike quasars -- super-massive black holes with masses more than a billion times that of the sun -- the black holes detected by Chandra in a sampling of 200 remote galaxies are a hundred times fainter and a thousand times less massive. But the data suggest baby black holes are present in at least 30 percent of the galaxies observed and possibly all of them.
The black holes were detected by capturing X-rays emitted as gas and dust, accelerated to relativistic velocities, were consumed. The Hubble Space Telescope captured faint images of galaxies in the Chandra target field, but because of the obscuring gas and dust, only X-rays made it out into open space and, eventually, Earth.
Schawinski said astronomers already suspected a direct relationship between galaxy formation and super massive black holes. Virtually every galaxy seen appears to harbor a massive black hole, including a 4-million-solar-mass hole at the center of Earth's Milky Way.
"Not only do galaxies contain black holes at the center, but galaxies and black holes seem to grow together," he said. "Big galaxies have big black holes at their center, small galaxies have small black holes. We believe they have this funamental symbiotic relationship (and) the growth of one regulates the growth of the other in a kind of feedback loop.
"What our observations of galaxies in the very early universe tell us is that these very early young galaxies at the dawn of the universe and their growing baby black holes already have some sort of deep, fundamental connection between them. They were already growing together, and so this chicken-and-egg problem of what was there first, the galaxy or the black hole, has been pushed all the way to the edge of the universe."
The Chandra observations seem to show that black holes are the result of collapsing clouds of gas, that early in the universe, less than a billion years after the big bang, there appears to be an intimate connection between the properties of these growing black holes and their host galaxies.
But, what ultimately is the function of a black hole in the universe? In a remarkable paper about the nature of space and the origin of time, Nikodem Poplawski, a physicist at Indiana University, suggests that a small change to the theory of gravity implies that our Universe inherited its arrow of time from the black hole in which it was born. “Our own Universe may be the interior of a black hole existing in another universe,” he concludes.
Poplawski says that the idea that black holes are the cosmic mothers of new universes is a natural consequence of a simple new assumption about the nature of spacetime. Poplawski points out that the standard derivation of general relativity takes no account of the intrinsic momentum of spin half particles. However there is another version of the theory, called the Einstein-Cartan-Kibble-Sciama theory of gravity, which does.
This theory predicts that particles with half integer spin should interact, generating a tiny repulsive force called torsion. In ordinary circumstances, torsion is too small to have any effect. But when densities become much higher than those in nuclear matter, it becomes significant. In particular, says Poplawski, torsion prevents the formation of singularities inside a black hole.
Astrophysicists have long known that our Universe is so big that it could not have reached its current size given the rate of expansion we see now. Instead, they believe it grew by many orders of magnitude in a fraction of a second after the Big Bang, the period known as inflation.
Poplawski's approach immediately solves the inflation problem, saying that torsion caused this rapid inflation, which means the Universe as we see it today can be explained by a single theory of gravity without any additional assumptions about inflation.
Another important corollary of Poplawski's approach is that it makes it possible for universes to be born inside the event horizons of certain kinds of black holes where torsion prevents the formation of a singularity but allows energy density to build up, which leads to the creation of particles on a massive scale via pair production, followed by the expansion of the new universe. "Such an expansion is not visible for observers outside the black hole, for whom the horizon's formation and all subsequent processes occur after infinite time," says Poplawski. For this reason, he emphasizes, the new universe is a separate branch of space time and evolves accordingly.
Poplawski's theory also suggests an solution to why time seems to flow in one direction but not in the other, even though the laws of physics are time symmetric.
Poplawski says the origin of the arrow of time comes from the asymmetry of the flow of matter into the black hole from the mother Universe. "The arrow of cosmic time of a universe inside a black hole would then be fixed by the time-asymmetric collapse of matter through the event horizon," he says. Translated, this means that our Universe inherited its arrow of time from its source. "Daughter universes," he says, "may inherit other properties from their mothers," implying that it may be possible to detect these properties, providing an experimental falsifiable proof of his idea.