Hungry Star: Mysteriously Dimming Galaxy is Actually Starving to Death
Scientists have finally solved a long-standing mystery about a flickering galaxy in the distant.
According to NASA's Chandra X-ray Observatory website, the galaxy, known as Markarian 1018, was once an active galaxy with an active galactic nucleus (AGN) or an extremely bright core. But Markarian 1018's AGN has been dimming over the last 30 years. Data from Chandra and other observatories suggest that the black hole at the center of the galaxy is actually starving to death.
Like Markarian 1018, several other galaxies have extremely bright cores or nuclei that are powered by material falling toward a supermassive black hole. However, when the black hole is not being fed enough fuel, the AGN's light dims. According to NASA, Markarian 1018 is different because it has changed type twice, from faint to bright AGN in the 1980's and then became faint again - about eight times fainter in X-rays - between 2010 and 2016.
Using data from the European Southern Observatory's (ESO) Very Large Telescope, the scientists ruled out the possibility that the increase in the brightness of the AGN was caused by a black hole eating a single star. Data from NASA's Chandra X-ray Observatory gathered in 2010 and 2016 showed that a surrounding cloud of gas was not hiding the AGN as earlier thought.
Instead, data from the Hubble Space Telescope, NASA's Galaxy Evolution Explorer (GALEX) and the Sloan Digital Sky Survey showed that the AGN had dimmed because the black hole is starving of infalling material. The starvation is also behind the fading of the AGN X-rays.
Astronomers believe that a second black hole in Markarian 1018 is disrupting the flow of material to the first black hole. According to NASA, a binary black hole is likely, as Markarian 1018 is a product of a collision and merger between two giant galaxies, each possibly containing a supermassive black hole at its core.
The findings are based on two new research papers that were published in the September 2016 issue of the Astronomy & Astrophysics journal.