NASA's Chandra X-ray Observatory may have found the most recent black hole formed in the Milky Way galaxy, sequestered in the remnants of a supernova called W49B. Scientists are uncertain about the actual existence of the black hole, but there are signs that point to its presence - the first of them being W49B's shape.
Researchers used the wavelengths W49B is radiating, including x-rays, and compared them to existing models of exploding stars. Unlike most supernovas, which occur symmetrically when they collapse - that is, they send material blasting away from the center in equal amounts in all directions - the W49B supernova jetted away material near the poles of its doomed star at a much higher speed than from its equator.
By tracing and identifying the distribution and amounts of different elements in the remnants, NASA explained, they found that while sulfur and silicon were spread throughout, iron was only present in half the of W49B. "In addition to its unusual signature of elements," Enrico Ramirez-Ruiz, an astropysicist at the University of California at Santa Cruz and co-author of the research, said in a press release, "This is seen in X-rays and several other wavelengths and points to an unusual demise for this star."
Compared to other supernovas, W49B is relatively close to the earth and an extreme case, which makes it ideal for study. Most massive stars that explode eventually collapse into an extremely dense, spinning neutron star, which can usually be detected through pulsing X-ray and radio waves. Researchers detected no sign of a neutron star in W49B, which leaves the other option of a black hole.
Gamma-ray bursts (GRBs) are also usually associated with the formation of black holes, but have only been observed from objects in distant glaxies. Although scientists have no evidence that W49B produced a GRB, it does exhibit qualities consistent with the emergence of a singularity.
These results were obtained after two and a half days of Chandra observation time, NASA's press release said, and the subsequent report will appear in Sunday's issue of the Astrophysics Journal. Sarah Pearson from the University of Copenhagen in Denmark is the other co-author.
