NASA's Chandra observatory spots spectacular eclipse of Black Hole

Optical and X-ray Images of NGC 1365 The large image shows an optical view of NGC 1365 from the ESO Very Large Telescope and the inset shows the Chandra X-ray Observatory view of the center of this galaxy. The bright source in the middle of the Chandra image shows the position of the supermassive black hole. During the eclipse the high energy X-rays from regions close to the black hole are blocked by dense gas clouds. Photo Credit: NASA/CXC/CfA/INAF/Risaliti Optical: ESO/VLT

Washington, Apr 13: NASA’s Chandra X ray observatory has captured a remarkable eclipse of the supermassive blackhole at the centre of the NGC 1365 galaxy.

Observations revealed a dense cloud of gas passing in front of the black hole, which blocked the emission of high-energy X-rays from materials close to the black hole.

This serendipitous alignment also allowed astronomers to measure the size of the disk of material around the black hole, said researchers.

An Eclipse of a Supermassive Black Hole These artist's representations explain how a supermassive black hole and the hot gas disk around it are eclipsed. The top panel shows the times when light from the bright disk surrounding the black hole can directly reach Chandra. The bottom panel shows when this light is blocked by a dense cloud of gas and only reflected light from the disk reaches Chandra. Photo Credit: NASA/CXC/M.Weiss

NGC 1365 contains a so-called active galactic nucleus, or AGN. Astronomers believe that the black hole at the centre of the AGN is fed by a steady stream of material, presumably in the form of a disk.

According to a statement by the observatory, material just about to fall into a black hole should be heated to millions of degrees before passing over the event horizon, or point of no return. This process causes the disk of gas around the central black hole in NGC 1365 to produce copious X-rays, but the structure is much too small to resolve directly with a telescope.

However, astronomers were able to measure the disk's size by observing how long it took for the black hole to go in and out of the eclipse. This was revealed during a series of observations of NGC 1365 obtained every two days over a period of two weeks in April 2006.

During five of the observations, high-energy X-rays from the central X-ray source were visible, but in the second one -- corresponding to the eclipse -- they were not, the statement said. (ANI)