doi:10.1038/nindia.2015.8 Published online 19 January 2015
Astrophysicists have developed an analytical model that provides new insights into how a rotating black hole influences the properties of hot gas and dust falling into it1. This model will help astrophysicists to probe and better understand how supermassive black holes at the centre of galaxies curve space–time and swallow matter.
Following their birth from the remnants of massive dying stars, black holes gain mass and generate intense gravity that sucks in vast amounts of gas and dust from nearby space. Once these materials cross a boundary of a black hole known as the event horizon, they are trapped inside the black hole forever ― even light cannot escape from the event horizon. But it remains unclear what really happens in the vicinity of a black hole’s event horizon.
To throw light on this enigma, the researchers developed an analytical model that probed how a black hole’s rotational motion affects the properties of materials that are plunging towards its event horizon.
Before falling into a black hole, matter rotates either parallel to the black hole’s spin or in the opposite direction. As falling matter emits radiation, it is possible to capture images of this radiation against the dark backdrop (shadow) of a black hole’s event horizon. The researchers found that their model could distinguish the directional patterns of falling matter by analyzing the spectral signatures of such images.
This technique of imaging the shadow of a black hole’s event horizon is known as black hole shadow imaging. “This model will be useful for studying shadow imaging of rotating super massive black holes at the centres of the Milky Way and other galaxies,” says lead researcher Tapas Kumar Das.
1. Das, T. K. et al. Black hole spin dependence of general relativistic multi-transonic accretion close to the horizon. New Astron. 37, 81–104 (2015)