Gravitational wave signatures of highly compact boson star binaries

Palenzuela, Carlos; Bezares, Miguel; Cardoso, Vítor; Lehner, Luis; Liebling, Steven L.; Pani, Paolo

doi:10.1103/physrevd.96.104058

Cited by 154 publications

(204 citation statements)

References 56 publications

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“…Importantly, we note that as time progresses the matter distribution approaches a spherical shape mainly due to: (i) significant scalar field radiation, and (ii) "gravitational cooling", where scalar field "blobs" with masses ≈ 1% of the initial mass are shed and propagate away 16 from the 16 We note in passing that analogue behavior has also been observed in other settings involving scalar field nonlinear interactions, e.g. scalar field collapse [25,190] and boson star collisions [189,191,192]. in Sec.…”

Section: Results and Observationsmentioning

confidence: 62%

Large-misalignment mechanism for the formation of compact axion structures: Signatures from the QCD axion to fuzzy dark matter

et al. 2020

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Axions are some of the best motivated particles beyond the Standard Model. We show how the attractive self-interactions of dark matter (DM) axions over a broad range of masses, from 10 −22 eV to 10 7 GeV, can lead to nongravitational growth of density fluctuations and the formation of bound objects. This structure formation enhancement is driven by parametric resonance when the initial field misalignment is large, and it affects axion density perturbations on length scales of order the Hubble horizon when the axion field starts oscillating, deep inside the radiation-dominated era. This effect can turn an otherwise nearly scale-invariant spectrum of adiabatic perturbations into one that has a spike at the aforementioned scales, producing objects ranging from dense DM halos to scalar-field configurations such as solitons and oscillons. We call this class of cosmological scenarios for axion DM production "the large-misalignment mechanism."We explore observational consequences of this mechanism for axions with masses up to 10 eV. For axions heavier than 10 −5 eV, the compact axion halos are numerous enough to significantly impact Earth-bound direct detection experiments, yielding intermittent but coherent signals with repetition rates exceeding one per decade and crossing times less than a day. These episodic increases in the axion density and kinematic coherence suggest new approaches for axion DM searches, including for the QCD axion. Dense structures made up of axions from 10 −22 eV to 10 −5 eV are detectable through gravitational lensing searches, and their gravitational interactions can also perturb baryonic structures and alter star formation. At very high misalignment amplitudes, the axion field can undergo self-interaction-induced implosions long before matter-radiation equality, producing potentially-detectable low-frequency stochastic gravitational waves.

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Section: Results and Observationsmentioning

confidence: 62%

Large-misalignment mechanism for the formation of compact axion structures: Signatures from the QCD axion to fuzzy dark matter

et al. 2020

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“…Furthermore, the merger of two ABSs might be much richer than that of two black holes. For instance, scalar modes might be excited in the post-merger phase, and the merger remnant might be either a distorted ABS or a black hole, depending on the mass of the binary components [32,37]. The mass-radius diagram in the right-top panel of Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Both BSs and oscillatons can arise naturally as the end-state of gravitational collapse of scalar fields [23,34,35] and share similar features. If BSs can form in the universe, they might also form binary systems which would be a novel gravitational-wave (GW) source [24,33,[36][37][38][39]. The hypothetical detection of a BS could provide indirect evidence for physics beyond the Standard Model [40,41].…”

Section: Introductionmentioning

confidence: 99%

Axion boson stars

Guerra

Macedo

Pani

2019

J. Cosmol. Astropart. Phys.

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We study novel solitonic solutions to Einstein-Klein-Gordon theory in the presence of a periodic scalar potential arising in models of axion-like particles. The potential depends on two parameters: the mass of the scalar field m a and the decay constant f a ; the standard case of the QCD axion is recovered when m a ∝ 1/f a . When f a → ∞ the solutions reduce to the standard case of "mini" boson stars supported by a massive free scalar field. As the energy scale f a of the scalar self-interactions decreases we unveil several novel features of the solution: new stability branches emerge at high density, giving rise to very compact, radially stable, boson stars. Some of the most compact configurations acquire a photon sphere. When f a is at the GUT scale, a boson star made of QCD axions can have a mass up to ten solar masses and would be more compact than a neutron star. Gravitational-wave searches for these exotic compact objects might provide indirect evidence for ultralight axion-like particles in a region not excluded by the black-hole superradiant instability.

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“…Unfolded by such findings, many astrophysical applications have followed suit in the community. Among them we underline hairy black holes, namely, black holes with nontrivial scalar fields which seem to contradict the non-hair conjecture (see [1] for a review), and new astrophysical compact configurations under the form of gravastars [2][3][4] and boson stars [5][6][7], as well as other long-lived scalar field configurations [8]. New phenomena can be triggered by such scalar fields and configurations, such as superradiance [9] and black hole bombs [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

New scalar compact objects in Ricci-based gravity theories

Afonso

Olmo

Orazi

et al. 2019

J. Cosmol. Astropart. Phys.

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Taking advantage of a previously developed method, which allows to map solutions of General Relativity into a broad family of theories of gravity based on the Ricci tensor (Ricci-based gravities), we find new exact analytical scalar field solutions by mapping the free-field static, spherically symmetric solution of General Relativity (GR) into quadratic f (R) gravity and the Eddingtoninspired Born-Infeld gravity. The obtained solutions have some distinctive feature below the wouldbe Schwarzschild radius of a configuration with the same mass, though in this case no horizon is present. The compact objects found include wormholes, compact balls, shells of energy with no interior, and a new kind of object which acts as a kind of wormhole membrane. The latter object has Euclidean topology but connects antipodal points of its surface by transferring particles and null rays across its interior in virtually zero affine time. We point out the relevance of these results regarding the existence of compact scalar field objects beyond General Relativity that may effectively act as black hole mimickers. *

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Gravitational wave signatures of highly compact boson star binaries

Cited by 154 publications

References 56 publications

Large-misalignment mechanism for the formation of compact axion structures: Signatures from the QCD axion to fuzzy dark matter

Large-misalignment mechanism for the formation of compact axion structures: Signatures from the QCD axion to fuzzy dark matter

Axion boson stars

New scalar compact objects in Ricci-based gravity theories

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