A star that exploded about 27,000 years ago may have produced the Galaxy?s youngest known black hole.?
Researchers using data from NASA?s Chandra X-Ray Observatory have discovered the remnant of a supernova that may contain the youngest black hole in the Milky Way Galaxy.
This supernova remnant, currently known as?W49B, is about 26,000 light years from Earth, and is believed to have exploded about 27,000 years ago. (From here, though, it looks like it happened 1,000 years ago, thanks to the joys of Relativity.) What?s unusual about W49B is it isn?t spherical, which most supernova remnants are. Instead, it?s elliptical.
?In addition to its unusual signature of elements, W49B also is much more elongated and elliptical than most other remnants,? said researcher Enrico Ramirez-Ruiz in a press release. ?This is seen in X-rays and several other wavelengths and points to an unusual demise for this star.?
This evidence is suggestive that rather than a typical supernova, this was actually a gamma-ray burst. As lead researcher Laura Lopez describes in a blog post, ?The Chandra images reveal that W49B does have a ?bar? of iron, and the data shows that the relative amount of silicon and sulfur is much less than what theory predicts for a typical core-collapse supernova. Thus, the shape and metals of W49B show the explosion has the jets we associate with gamma-ray bursts.?
Most supernovas result in the formation of a neutron star ? a small, incredibly dense body comprised almost entirely of neutrons. Neutron stars have a distinctive X-ray characteristic, which the research team looked for. Upon examination of data from the Chandra telescope, however, researchers found no sign of one. This indicates that the remnant is instead a black hole. If that finding is confirmed, it would make the black hole the youngest known in the Galaxy.
?With the superb imaging of Chandra, we looked for a neutron star, and we couldn?t find anything,? said Lopez in her blog post. ?In fact, the deep observation allowed us to say there?s no neutron star in W49B that?s even 1/100 as bright as astronomers think it would be. This result supports the fact that W49B?s supernova formed a black hole, which is consistent with the explosion having been a gamma-ray burst.?
The research will be published in the Astrophysical Journal.
(Image credit:?Credit: X-ray: NASA/CXC/MIT/L.Lopez et al.; Infrared: Palomar; Radio: NSF/NRAO/VLA)
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