Does gravitomagnetic monopole exist? A clue from a black hole X-ray binary

Chandrachur Chakraborty, Sudip Bhattacharyya

Published 2017-12-04Version 1

The gravitomagnetic monopole is the proposed gravitational analogue of Dirac's magnetic monopole, and if detected, a new area of fundamental physics will be opened. Here we find the first observational evidence of such a monopole in the following way. Three primary methods to measure the black hole spin, based on the relativistic precession model of quasi-periodic oscillations in X-rays, broad relativistic X-ray spectral line and X-ray continuum spectrum, give significantly different spin values for the accreting black hole in GRO J1655--40. We demonstrate that the inclusion of just one additional parameter, that is the so-called NUT parameter or the gravitomagnetic monopole, can not only make the spin and other parameter values inferred from these three independent methods consistent with each other, but also make the inferred black hole mass consistent with an independently measured mass value. We argue that this evidence of the gravitomagnetic monopole in nature is not a result of fine-tuning, and hence is robust within our paradigm. Finally, our results tentatively suggest that the collapsed object in GRO J1655--40 could be a naked singularity.