Relativistic Bose–Einstein condensates: a new system for analogue models of gravity

Fagnocchi, Serena; Finazzi, Stefano; Liberati, Stefano; Kormos, Márton; Trombettoni, Andrea

doi:10.1088/1367-2630/12/9/095012

Cited by 107 publications

(218 citation statements)

References 60 publications

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“…As for the dynamics of DM, the BEC wavefunction and its fluctuations should be governed by the GrossPitaevskii equation (GPE) or its relativistic generalization [52,53] …”

mentioning

confidence: 99%

Dark matter and dark energy from a Bose–Einstein condensate

Das

Bhaduri

2015

Class. Quantum Grav.

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We show that Dark Matter consisting of bosons of mass of about 1 eV or less has critical temperature exceeding the temperature of the universe at all times, and hence would have formed a Bose-Einstein condensate at very early epochs. We also show that the wavefunction of this condensate, via the quantum potential it produces, gives rise to a cosmological constant which may account for the correct dark energy content of our universe. We argue that massive gravitons or axions are viable candidates for these constituents. In the far future this condensate is all that remains of our universe.The basic contents of our universe in terms of Dark Matter (DM), Dark Energy (DE), visible matter and radiation, and also its accelerated expansion in recent epochs has been firmly established by a number of observations now [1][2][3][4]. However although DM constitutes about 25% and DE about 70% of all matter-energy content, the constituents of DM and the origin of a tiny cosmological constant, or DE, of the order of 10 −123 in Planck units, which drives this acceleration, remains to be understood. In this paper we show that if DM is assumed to consist of a gas of bosons of mass m, then for m ≤ 1eV , the critical temperature below which they will form a Bose-Einstein condensate (BEC) exceeds the temperature of the universe at all times. Therefore they would form such a condensate at very early epochs, in which a macroscopic fraction of the bosons fall to the ground state with little or no momentum and zero pressure, and therefore may be considered as viable candidates for cold DM (CDM). Further, via the quantum potential that it produces, the macroscopic wavefunction of the condensate gives rise to a positive cosmological constant in the Friedmann equation, whose magnitude depends on m, and for m ≃ 10 −32 eV , one obtains the observed value of the cosmological constant. Therefore bosons with this tiny mass can account for both DM and DE in our universe. We argue that massive gravitons or axions are viable candidates for these bosons. Finally we speculate on the ultimate fate of our universe, and end with some open problems.To compute the critical temperature of an ideal gas of bosons constituting DM, we first note that these must have a mass, however small, and with average interparticle distances (N/V ) −1/3 (where N = total number of bosons in volume V ) comparable or smaller than the * email: saurya.das@uleth.ca † email: bhaduri@physics.mcmaster.ca thermal de Broglie wavelength hc/k B T , such that quantum effects start to dominate. Identifying this temperature of a bosonic gas to the critical temperature T c (below which the condensate forms) we get k B T c ≃ hc(N/V ) 1/3 . A more careful calculation for ultra-relativistic noninteracting bosons with a tiny mass gives [5][6][7] In the above N = N B + N R , N B being the number of bosons in the BEC, and N R outside it, both consisting of bosons of small mass as discussed earlier, η is the polarization factor and ζ(3) ≈ 1.2. Also a is the cosmological scale factor, L = L 0 a i...

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“…As for the dynamics of DM, the BEC wavefunction and its fluctuations should be governed by the GrossPitaevskii equation (GPE) or its relativistic generalization [52,53] …”

mentioning

confidence: 99%

Dark matter and dark energy from a Bose–Einstein condensate

Das

Bhaduri

2015

Class. Quantum Grav.

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“…(32)- (33). Therefore, the differential scattering coss section at long wavelengths, α + α 2 + β + γ 2 1, for a massive fermion in the acoustic black hole background is given as follows:…”

Section: Fermion Field In the Acoustic Black Hole Backgroundmentioning

confidence: 99%

“…These advances are important for a better insight into the understanding of quantum gravity. In addition, the study of a relativistic version of acoustic black holes was presented in [31][32][33][34]. Furthermore, the acoustic black hole metrics obtained from a relativistic fluid in a noncommutative spacetime [35] and Lorentz-violating Abelian Higgs model [36,37] have been considered.…”

Section: Introductionmentioning

confidence: 99%

Aharonov–Bohm effect for a fermion field in a planar black hole “spacetime”

et al. 2017

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In this paper we consider the dynamics of a massive spinor field in the background of the acoustic black hole spacetime. Although this effective metric is acoustic and describes the propagation of sound waves, it can be considered as a toy model for the gravitational black hole. In this manner, we study the properties of the dynamics of the fermion field in this "gravitational" rotating black hole as well as the vortex background. We compute the differential cross section through the use of the partial wave approach and show that an effect similar to the gravitational AharonovBohm effect occurs for the massive fermion field moving in this effective metric. We discuss the limiting cases and compare the results with the massless scalar field case.

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“…This type of expansion has been recently applied to mimic an open FRW metric in a relativistic BE system [16,36]. In this model the radial three-velocity in radial coordinates x µ = (t, r, θ, φ) is a simple function v = r/t.…”

Section: B Spherical Bjorken Expansionmentioning

confidence: 99%

Cosmological particle creation in a hadronic fluid

Bilić

Tolić

2015

Phys. Rev. D

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Acoustic perturbations in an expanding hadronic fluid at temperatures below the chiral transition point represent massless pions propagating in curved spacetime geometry. In comoving coordinates the corresponding analog metric tensor describes a hyperbolic Friedmann-Robertson-Walker (FRW) spacetime. We study the analog cosmological particle creation of pions below the critical point of the chiral phase transition. We compare the cosmological creation spectrum with the spectrum of analog Hawking radiation at the analog trapping horizon.

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Relativistic Bose–Einstein condensates: a new system for analogue models of gravity

Cited by 107 publications

References 60 publications

Dark matter and dark energy from a Bose–Einstein condensate

Dark matter and dark energy from a Bose–Einstein condensate

Aharonov–Bohm effect for a fermion field in a planar black hole “spacetime”

Cosmological particle creation in a hadronic fluid

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