By Dheeraj Pasham

The paper outlines various forms of signals emanating from near massive black holes after they tidally disrupt stars that come close to them. One such class of signals is recurring modulations of the X-ray flux. Because X-rays originate from the deep gravitational potential in the immediate vicinity of black holes, they encode information about black hole's fundamental properties like the spin. With the current telescope, such signals can be found, and black hole spins can be constrained, in the nearby Universe, i.e., within a few hundred megaparsecs. In the coming decade, with Athena, similar signals could be found to a redshift of up to 2. Simulated Athena power density spectra showing a signal similar to that detected in a nearby tidal disruption event (at 131 seconds) but at redshifts of 0.5 (left) and 2 (right panel). This would allow astronomers to measure the distribution of supermassive black hole spin at different ages of the Universe. Such a measurement would directly constrain models of how SMBHs grew over the cosmic age.

Access to the manuscript in ADS.