Astronomers Mistaken Supermassive Black Hole Munching a Star as the Brightest Supernova Ever Found
A new study revealed that astronomers, who have classified a incredibly luminous outburst detected by the All-Sky Automated Survey for Supernovae (ASAS-SN) last year as the brightest supernova ever found, were mistaken because the luminous outburst may actually be a supermassive black hole ripping an unfortunate star.
The study, published in the journal Nature Astronomy, showed that the luminous event, dubbed as ASASSN-15lh, was caused by a star being disintegrated under the strong gravitational pull of a supermassive black hole up to billion times the mass of sun.
"We observed the source for 10 months following the event and have concluded that the explanation is unlikely to lie with an extraordinarily bright supernova," said Giorgos Leloudas, an astrophysicist at the Weizmann Institute of Science in Rehovot, Israel, and the Dark Cosmology Centre in Denmar and lead author of the study, in a report from The Sydney Morning Herald. "Our results indicate that the event was probably caused by a rapidly spinning supermassive black hole as it destroyed a low-mass star."
For the study, the researchers observed ASASSN-15lh for 10 months after its initial discovery. The researchers also use images taken by the Hubble Space Telescope to find the exact location of the ASASSN-15lh.
First observed sky at the border of the southern constellations Indus and Tucana, ASASSN-15lh happened about 3.8 billion light years from Earth. The luminous outburst gave off about 570 billion times more light than the sun does at its peak. Due to this, the astronomers who first observed the event classified it as superluminous supernova.
However, additional data of the ASASSN-15lh revealed that number of factors suggesting that the outburst is not caused by a supernova. Evidences point out that the luminous outburst observed by the astronomers was the byproduct of the so-called "tidal disruption".
Tidal disruption occurred when a supermassive black hole spins so rapidly that it drags a passing star, tearing it apart and sending its debris and matter around the accretion disk of the black hole. The huge heat generated by the ripping apart of the star and the colliding of the scattered debris caused a massive burst of light, which at first appeared to be a supernova.
The researchers noted that their tidal disruption theory is not fully certain. However, a supermassive black hole is the most likely explanation to the re-brightening observed in ASASSN-15lh.