Colliding Black Holes and Gravitational Waves

Abstract

Physically relevant solutions in general relativity often contain spacetime singularities, which are typically interpreted as a sign of breakdown of the theory at high densities/curvatures. Hence, there has been a growing interest in exploring phenomenological scenarios that describe singularity-free black holes, gravitational collapses, and cosmological models. We examine the metric put forth by Mazza, Franzin & Liberati for a rotating regular black hole and estimate the regularization parameter l based on existing X-ray and gravitational wave data for black holes. When l = 0, the solution corresponds to the singular Kerr solution of general relativity, while a non-zero value of l yields a regular black hole or a regular wormhole. The analysis reveals that the available data support a value of l that is close to zero.

Conservative self-force correction to the innermost stable circular orbit: Comparison with multiple post-Newtonian-based methods

“…Lastly, Sec. III G discusses (15) the Shanks transformation, a series acceleration method that is applied to several of the above PN-based ISCO calculations (which are themselves each computed at multiple PN orders).…”

“…One such method is numerical relativity (NR), the numerical solution of Einstein's equation without approximation. This approach has had much recent success (see [13][14][15][16] for reviews), but computational limitations currently restrict it to modeling binaries with mass ratios q 0.1 [17] (however, see Refs. [18][19][20] for recent progress).…”

Dynamical shift condition for unequal mass black hole binaries

“…Waveform comparison using formula (6) We repeated the analysis of Sec. IV A with the waveforms we obtain using Eq.…”

“…(5) and (6). We did perform some experimentation along this line where we varied w = w 1 = w 2 to see if we could get a useful effect of the coordinate size of the apparent horizons on the numerical grid.…”

“…While initial simulations focused on binaries of equal-mass, zero spin, and quasicircular inspirals, there currently is a large effort to explore the parameter space of binaries, e.g. [4][5][6][7]. A key part of studying the parameter space is to simulate binaries with intermediate mass-ratios.…”