Scientists have hypothesized that black holes, super dense masses with gravity so strong not even light escapes, can vacuum up stars and shred them to pieces and squash them to smithereens. Trouble is, proof of the ripped-up stars eluded astronomers - until now.
An international team of astrophysicists report in the latest issue of the Astrophysical Journal about two potential torn-apart stars. The surveyors found the needle in galaxies' worth of hay; using the Sloan Digital Sky Survey (SDSS), the researchers combed through data of two million galaxies observed over 10 years.
The group found two cases of tidal disruption flares - intense radiation that lasts days to months and signify the remnants of stars crashing into themselves as they are torn apart by black holes.
Searching through 2.6 million galaxies was actually a lot of fun-there is so much to discover! lead author Sjoert van Velzen said in a statement. The first-year graduated student worked with Glennys Farrar, physics professor at New York University and senior scientist for the project.
Based on our search criteria and observing two TDFs that met those criteria, the rate of TDFs is about once per 100,000 years, per galaxy. It's quite thrilling to have been able to make such a measurement.
The high energy flares from torn-apart stars are difficult to distinguish from other sources of radiation flares in the universe including supernovae. However, black holes can have a signature halo of gas and dust from galaxies that feed the black holes.
The researchers found multiple flares, but winnowed down the list to flares in the middle of galaxies where black holes typically reside. Further, the researchers found that the black hole flares colored blue instead of the typical red color of supernovae.
The next step is to develop models to explain in detail the flares' properties and duration, and address the question of whether TDFs could be responsible for producing Ultrahigh Energy Cosmic Rays, whose sources have been elusive up to now, Farrar said. The cosmic rays are some of the highest sources of energy known in the universe. It is very exciting that we are on the verge of obtaining a large and better-observed sample of TDFs to study.