Analysis of Bose-Einstein condensation times for self-interacting scalar dark matter

Kirkpatrick, Kay; Mirasola, Anthony E.; Prescod-Weinstein, Chanda

doi:10.1103/physrevd.106.043512

“…But it may be even more applicable to lower-mass solitons from higher-mass SDM particles. Due to the scale-invariance of the Gross-Pitaevskii-Poisson equations, the simulations in section 3 solve the dynamics of a family of systems of characterized by the particle mass m. The QCD axion has a much heavier particle mass, m = 10 −4 eV, and forms solitons of a typical mass on the order of 10 −14 M and radius on the order of 300 km [82][83][84][85][86]. Our simulations suggest that in a gravitational well caused by ordinary hadronic matter of comparable mass, the soliton can support vortices in its cores with lifetimes of many dynamical times, going up to effectively infinite lifetime if the central mass is far-dominant.…”

Section: Discussionmentioning

confidence: 99%

Scalar dark matter vortex stabilization with black holes

Glennon¹,

Mirasola²,

Musoke³

et al. 2023

Preprint

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Galaxies and their dark-matter halos are commonly presupposed to spin. But it is an open question how this spin manifests in halos and soliton cores made of scalar dark matter (SDM, including fuzzy/wave/ultralight-axion dark matter). One way spin could manifest in a necessarily irrotational SDM velocity field is with a vortex. But recent results have cast doubt on this scenario, finding that vortices are generally unstable except with substantial repulsive self-interaction. In this paper, we introduce an alternative route to stability: in both (non-relativistic) analytic calculations and simulations, a black hole or other central mass at least as massive as a soliton can stabilize a vortex within it. This conclusion may also apply to stellar-scale Bose stars.

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“…The relevant timescale tracks the relaxation time via self-interactions where in the last equality we defined λ ≡ −m 2 /f 2 a , valid if the ULDM is an axion with decay constant f a . This represents the typical time a particle in a gas with density ρ dm and average square velocity v 2 dm takes to change its velocity by order one via the self-interactions mediated by λ, in the absence of external gravitational potentials [57,58]. This timescale τ rel is therefore the analogue of the gravitational relaxation time [31], with gravitational interactions replaced by the self-interactions.…”

Section: Phases Of Formationmentioning

confidence: 99%

“…The evolution is carried out with periodic boundary conditions and a standard second-order pseudo-spectral method, employed e.g. in [31,34,57,58,152], to which we refer for all the details. (Note that the two additional parameters {N x , L} need to be specified in a simulation.…”

Section: Jcap12(2023)021mentioning

confidence: 99%

A generic formation mechanism of ultralight dark matter solar halos

Budker,

Eby,

Gorghetto

et al. 2023

J. Cosmol. Astropart. Phys.

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As-yet undiscovered light bosons may constitute all or part of the dark matter (DM) of our Universe, and are expected to have (weak) self-interactions. We show that the quartic self-interactions generically induce the capture of dark matter from the surrounding halo by external gravitational potentials such as those of stars, including the Sun. This leads to the subsequent formation of dark matter bound states supported by such external potentials, resembling gravitational atoms (e.g. a solar halo around our own Sun). Their growth is governed by the ratio ξ foc ≡ λdB/R ⋆ between the de Broglie wavelength of the incoming DM waves, λdB, and the radius of the ground state R ⋆. For ξ foc ≲ 1, the gravitational atom grows to an (underdense) steady state that balances the capture of particles and the inverse (stripping) process. For ξ foc ≳ 1, a significant gravitational-focusing effect leads to exponential accumulation of mass from the galactic DM halo into the gravitational atom. For instance, a dark matter axion with mass of the order of 10-14 eV and decay constant between 107 and 108 GeV would form a dense halo around the Sun on a timescale comparable to the lifetime of the Solar System, leading to a local DM density at the position of the Earth 𝒪(104) times larger than that expected in the standard halo model. For attractive self-interactions, after its formation, the gravitational atom is destabilized at a large density, which leads to its collapse; this is likely to be accompanied by emission of relativistic bosons (a `Bosenova').

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“…But it may be even more applicable to lower-mass solitons from higher-mass SDM particles. Due to the scale-invariance of the Gross-Pitaevskii-Poisson equations, the simulations in section 3 solve the dynamics of a family of systems of characterized by the particle mass m. The QCD axion has a much heavier particle mass, perhaps m = O(10 −4 ) eV, and may form solitons with mass on the order of 10 −14 M and radius on the order of 300 km; the exact mass an radius depends on other properties of the axion [85][86][87][88][89]. Our simulations suggest that in a gravitational well caused by ordinary hadronic matter of comparable mass, the soliton can support vortices in its cores with lifetimes of many dynamical times, going up to effectively infinite lifetime if the central mass is far-dominant.…”

Section: Jcap07(2023)004mentioning

confidence: 99%

Scalar dark matter vortex stabilization with black holes

Glennon

¹

,

Mirasola

²

,

Musoke

³

et al. 2023

J. Cosmol. Astropart. Phys.

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4

0

View full text Add to dashboard Cite

Galaxies and their dark-matter halos are commonly presupposed to spin. But it is an open question how this spin manifests in halos and soliton cores made of scalar dark matter (SDM, including fuzzy/wave/ultralight-axion dark matter). One way spin could manifest in a necessarily irrotational SDM velocity field is with a vortex. But recent results have cast doubt on this scenario, finding that vortices are generally unstable except with substantial repulsive self-interaction. In this paper, we introduce an alternative route to stability: in both (non-relativistic) analytic calculations and simulations, a black hole or other central mass at least as massive as a soliton can stabilize a vortex within it. This conclusion may also apply to AU-scale halos bound to the sun and stellar-mass-scale Bose stars.

show abstract

Analysis of Bose-Einstein condensation times for self-interacting scalar dark matter

Cited by 14 publications

References 33 publications

Scalar dark matter vortex stabilization with black holes

Scalar dark matter vortex stabilization with black holes

A generic formation mechanism of ultralight dark matter solar halos

Scalar dark matter vortex stabilization with black holes

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