It was detected in June 2018 by astronomers at the twin ATLAS telescopes located in Hawaii. A huge flash that seemed to appear suddenly. The signal was identified as AT2018cow , popularly known as “The Cow”, but what was thought to be a supernova was a much more powerful event; brighter and short-lived, but of unknown origin.
Now, MIT astrophysicist DJ Pasham and his colleagues have seen the first direct evidence of what La Vaca left behind. “We may be seeing the birth of a black hole or a neutron star,” says Pasham. “This happens in normal supernovae, but we haven’t seen it before because it’s a very complicated process. We think this new evidence opens up possibilities for finding baby black holes or baby neutron stars.”
The initial flash originated about 200 million light-years away and was 10 times brighter than an ordinary supernova , the explosion that marks the death of a massive star.
X-rays from the cow blink approximately every 4 milliseconds , which means that the object that produces them must be no more than 1,000 kilometers wide. Here we have the proposed theory: only a neutron star or a black hole fits these requirements. However, there are still some unanswered questions with either of these two models. For a neutron star, the narrow frequency range of the emissions is difficult to explain. For a black hole, features like brightness and X-ray stability are just as difficult to fit together.
“Whenever there is a new phenomenon, there is the excitement that it can say something new about the universe,” says Pasham.
Referencia: D. Pasham et al. Evidence for a compact object in the aftermath of the extragalactic transient AT2018cow. Nature Astronomy. Published December 13, 2021. doi: 10.1038/s41550-021-01524-8.
