Gravitational-wave signatures of exotic compact objects and of quantum corrections at the horizon scale

By V. Cardoso, Seth Hopper, C. F. Macedo, Carlos Palenzuela, Paolo Pani. 2016

399 citations recorded by the source corpus.

Gravitational waves from binary coalescences provide one of the cleanest signatures of the nature of compact objects. It has been recently argued that the postmerger ringdown waveform of exotic ultracompact objects is initially identical to that of a black hole, and that putative corrections at the horizon scale will appear as secondary pulses after the main burst of radiation. Here we extend this analysis in three important directions: (i) we show that this result applies to a large class of exotic compact objects with a photon sphere for generic orbits in the test-particle limit; (ii) we investigate the late-time ringdown in more detail, showing that it is universally characterized by a modulated and distorted train of ``echoes''of the modes of vibration associated with the photon sphere; (iii) we study for the first time equal-mass, head-on collisions of two ultracompact boson stars and compare their gravitational-wave signal to that produced by a pair of black holes. If the initial objects are compact enough as to mimic a binary black-hole collision up to the merger, the final object exceeds the maximum mass for boson stars and collapses to a black hole. This suggests that\char22{}in some configurations\char22{}the coalescence of compact boson stars might be almost indistinguishable from that of black holes. On the other hand, generic configurations display peculiar signatures that can be searched for in gravitational-wave data as smoking guns of exotic compact objects.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/31153f9ff94f70218dba569ead4af5c347b2558c

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Citations in the corpus

Dynamical boson stars (2012, methodology): “In particular for boson stars, the relative phase determines the GW signature [299, 298, 83].”
Tests for the existence of black holes through gravitational wave echoes (2017, background): “The most prominent signature is the appearance of late-time echoes in the waveforms [10, 11, 49, 50].”
Phenomenological aspects of black holes beyond general relativity (2018, background): “Previous works (including [179, 181, 182, 185, 187]) have not analyzed this issue explicitly, perhaps due to particular choices of initial conditions for gravitational radiation.”
Born–Infeld inspired modifications of gravity (2017, background): “On the other hand, though the physics at the photon sphere has been explored and understood to some detail [360, 337], much research is still needed in order to obtain observational signatures for gravitational waves out of the merging of two such black holes, as well as the potential existence of g”
Science case for the Einstein telescope (2019, background): “is given by the Schwarzschild radius R S, eects due to quantum gravity are governed by a factor log(l Pl=R S), and can manifest themselves through a series of echos after the initial ringdown signal [86,90,91], emitted with a time delay ˝ echo ˘(R S=c)log(R S=l Pl). For instance, for a nal object wi”
Gravitational Condensate Stars: An Alternative to Black Holes (2001, neutral): “Nevertheless a regular QBH such as a gravastar could produce a GW ‘echo’ at multiples of the characteristic time ∆ t ∼ 2 GM ln ( 1/ ε ) (A7) after the compact object merger event [80].”