Boson stars have attracted much attention in recent decades as simple, self-consistent models of compact objects and also as self-gravitating structures formed in some dark-matter scenarios. Direct detection of these hypothetical objects through electromagnetic signatures would be unlikely because their bosonic constituents are not expected to interact significantly with ordinary matter and radiation. However, binary boson stars might form and coalesce emitting a detectable gravitational wave signal, which might distinguish them from ordinary compact object binaries containing black holes and neutron stars. We study the merger of two boson stars by numerically evolving the fully relativistic Einstein-Klein-Gordon equations for a complex scalar field with a solitonic potential that generates very compact boson stars. Owing to the steep mass-radius diagram, we can study the dynamics and gravitational radiation from unequal-mass binary boson stars with mass ratios up to q approximate to 23 without the difficulties encountered when evolving binary black holes with large mass ratios. Similar to the previously studied equal-mass case, our numerical evolutions of the merger produce either a nonspinning boson star or a spinning black hole, depending on the initial masses and on the binary angular momentum. We do not find any evidence of synchronized scalar clouds forming around either the remnant spinning black hole or around the remnant boson stars. Interestingly, in contrast to the equal-mass case, one of the mechanisms to dissipate angular momentum is now asymmetric and leads to large kick velocities (up to a few 10(4) km/s), which could produce wandering remnant boson stars. We also compare the gravitational wave signals predicted from boson star binaries with those from black hole binaries and comment on the detectability of the differences with ground interferometers.

Gravitational waves and kicks from the merger of unequal mass, highly compact boson stars / Bezares, Miguel; Bošković, Mateja; Liebling, Steven; Palenzuela, Carlos; Pani, Paolo; Barausse, Enrico. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 105:6(2022), pp. 1-23. [10.1103/PhysRevD.105.064067]

Gravitational waves and kicks from the merger of unequal mass, highly compact boson stars

Bezares, Miguel;Bošković, Mateja;Pani, Paolo;Barausse, Enrico
2022-01-01

Abstract

Boson stars have attracted much attention in recent decades as simple, self-consistent models of compact objects and also as self-gravitating structures formed in some dark-matter scenarios. Direct detection of these hypothetical objects through electromagnetic signatures would be unlikely because their bosonic constituents are not expected to interact significantly with ordinary matter and radiation. However, binary boson stars might form and coalesce emitting a detectable gravitational wave signal, which might distinguish them from ordinary compact object binaries containing black holes and neutron stars. We study the merger of two boson stars by numerically evolving the fully relativistic Einstein-Klein-Gordon equations for a complex scalar field with a solitonic potential that generates very compact boson stars. Owing to the steep mass-radius diagram, we can study the dynamics and gravitational radiation from unequal-mass binary boson stars with mass ratios up to q approximate to 23 without the difficulties encountered when evolving binary black holes with large mass ratios. Similar to the previously studied equal-mass case, our numerical evolutions of the merger produce either a nonspinning boson star or a spinning black hole, depending on the initial masses and on the binary angular momentum. We do not find any evidence of synchronized scalar clouds forming around either the remnant spinning black hole or around the remnant boson stars. Interestingly, in contrast to the equal-mass case, one of the mechanisms to dissipate angular momentum is now asymmetric and leads to large kick velocities (up to a few 10(4) km/s), which could produce wandering remnant boson stars. We also compare the gravitational wave signals predicted from boson star binaries with those from black hole binaries and comment on the detectability of the differences with ground interferometers.
2022
105
6
1
23
064067
10.1103/PhysRevD.105.064067
https://arxiv.org/abs/2201.06113
Bezares, Miguel; Bošković, Mateja; Liebling, Steven; Palenzuela, Carlos; Pani, Paolo; Barausse, Enrico
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/127909
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