Black Hole Birth Can Be Observed For First Time, Study Says
Astronomers are scanning the heavens for flashes of light that may signal the formation of a black hole, empowered by a new theory that indicates a dying star will generate a distinct flash of light that will allow man to witness the birth of a new black hole for the first time.
While in rare cases some dying stars that result in black holes explode as highly recognizable gamma-ray bursts, the old line of thinking goes that most black holes form uncharismatically when a star dies, with more of a disappearance, rather than a burst of energy.
But California Institute of Technology postdoctoral scholar Tony Piro thinks that the old notion that a dying star produces a black hole without much spectacle might not hold true.
"Maybe they're not as boring as we thought," Piro said in a Caltech news release.
The accepted theory of black hole formation is that when a star dies it collapses under its own weight. As it collapses, the protons and electrons that make up the star's core merge and produce neutrons. In its final stage of death, the star briefly becomes an extremely dense, energy-packed object called a neutron star before collapsing into a black hole. The energy produced is immense.
In the 1980s a physicist suggested that as energy flows out from the core of the dying star a layer of hydrogen gas would be forced out, generating a shock wave that would rush from the star at 2 million miles per hour.
Researchers recently determined that the shock wave heats the gasses present as the star is dying, generating a glow from the heat. The glowing gas would be a promising sign that a black hole is forming. But the glow has not been observed because it is thought to be relatively dim compared to the light of other stars, hard to see, even in galaxies relatively close to Earth.
But Piro's new calculations indicate that the flash produced from heated gas formed as a star is dying is 10 to 100 times brighter than the previous predictions. The flash, which would shine for as long as 10 days before fading, would be very bright in optical wavelengths-and at its very brightest in ultraviolet wavelengths.
"That flash is going to be very bright, and it gives us the best chance for actually observing that this event occurred," Piro said.
Piro reports that no black-hole flashes have been observed yet. But he said that now that astronomers know what to look for, they should be able to spot at least one black hole formation per year.
His research is published in The Astrophysical Journal.