Cold Bose stars

Breit, J.D.; Gupta, Subhash; Zaks, A.

doi:10.1016/0370-2693(84)90764-0

Cited by 104 publications

(66 citation statements)

References 3 publications

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“…The kinetic and interaction terms can be written in the compact form reported in Eq. (50), in which we made use of the acoustic metric emerging from the interaction of the NGB with the vacuum fluctuations.…”

Section: Discussionmentioning

confidence: 99%

“…Bose stars are stellar objects consisting of a large number of bosons in which the boson wave-function varies inside the star, see for example [49]. For noninteracting bosons with mass m, the maximum mass of a Bose star has been determined in [50] and turns out to be M max = 0.633/(Gm), where G is the gravitational constant. For self-interacting bosons, the maximum mass can be larger, as shown in [51] for axion stars.…”

Section: Discussionmentioning

confidence: 99%

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Scrutinizing the pion condensed phase

et al. 2017

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Abstract. When the isospin chemical potential exceeds the pion mass, charged pions condense in the zeromomentum state forming a superfluid. Chiral perturbation theory provides a very powerful tool for studying this phase. However, the formalism that is usually employed in this context does not clarify various aspects of the condensation mechanism and makes the identification of the soft modes problematic. We re-examine the pion condensed phase using different approaches within the chiral perturbation theory framework. As a first step, we perform a low-density expansion of the chiral Lagrangian valid close to the onset of the Bose-Einstein condensation. We obtain an effective theory that can be mapped to a Gross-Pitaevskii Lagrangian in which, remarkably, all the coefficients depend on the isospin chemical potential. The lowdensity expansion becomes unreliable deep in the pion condensed phase. For this reason, we develop an alternative field expansion deriving a low-energy Lagrangian analog to that of quantum magnets. By integrating out the "radial" fluctuations we obtain a soft Lagrangian in terms of the Nambu-Goldstone bosons arising from the breaking of the pion number symmetry. Finally, we test the robustness of the second-order transition between the normal and the pion condensed phase when next-to-leading-order chiral corrections are included. We determine the range of parameters for turning the second-order phase transition into a first-order one, finding that the currently accepted values of these corrections are unlikely to change the order of the phase transition.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Scrutinizing the pion condensed phase

et al. 2017

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“…In order to determine the properties of the mixed star equilibrium configurations described in the previous section, we performed long-term numerical evolutions of the discretized Einstein-Klein-Gordon-Hydrodynamic system (9).…”

Section: Numerical Simulationsmentioning

confidence: 99%

“…al. [6] (and further studied in [7,8]), where the fermionic matter was described by a perfect fluid with the Chandrasekhar equation of state, while the bosonic component is modeled by using a real quantized scalar field as in [9]. The bosons and the fermion particles are coupled only through gravity (notice however that non-minimal couplings with the scalar field can arise in other scenarios, such as in neutron stars with hidden extra dimensions [10] or in tensor-scalar theories of gravitation [11]).…”

Section: Introductionmentioning

confidence: 99%

Dynamical evolution of fermion-boson stars

et al. 2013

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Compact objects, like neutron stars and white dwarfs, may accrete dark matter, and then be sensitive probes of its presence. These compact stars with a dark matter component can be modeled by a perfect fluid minimally coupled to a complex scalar field (representing a bosonic dark matter component), resulting in objects known as fermion-boson stars. We have performed the dynamical evolution of these stars in order to analyze their stability, and to study their spectrum of normal modes, which may reveal the amount of dark matter in the system. Their stability analysis shows a structure similar to that of an isolated (fermion or boson) star, with equilibrium configurations either laying on the stable or on the unstable branch. The analysis of the spectrum of normal modes indicates the presence of new oscillation modes in the fermionic part of the star, which result from the coupling to the bosonic component through the gravity.

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“…Boson stars were introduced by Kaup (1968) and Ruffini & Bonazzola (1969) in the 1960s. Early works on boson stars (Thirring 1983;Breit et al 1984;Takasugi & Yoshimura 1984;van der Bij & Gleiser 1987) were motivated by the axion field that was proposed as a possible solution to the strong CP problem in QCD. For particles with mass m ∼ 1 GeV/c 2 , the maximum mass of a boson star, called the Kaup mass, is much lower than the solar mass (M Kaup ∼ 10 −19 M !…”

Section: Introductionmentioning

confidence: 99%

Growth of perturbations in an expanding universe with Bose-Einstein condensate dark matter

Chavanis

2012

A&A

148

201

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We study the growth of perturbations in an expanding Newtonian universe with Bose-Einstein condensate (BEC) dark matter. We first ignore special relativistic effects and derive a differential equation that governs the evolution of the density contrast in the linear regime. This equation, which takes quantum pressure and self-interaction into account, can be solved analytically in several cases. We argue that an attractive self-interaction can enhance the Jeans instability and fasten the formation of structures. Then, we take pressure effects (coming from special relativity) into account in the evolution of the cosmic fluid and add the contribution of radiation, baryons, and dark energy (cosmological constant). For BEC dark matter with repulsive self-interaction (positive pressure) the scale factor increases more rapidly than in the standard ΛCDM model where dark matter is pressureless, while it increases less rapidly for BEC dark matter with attractive self-interaction (negative pressure). We study the linear development of the perturbations in these two cases and show that the perturbations grow faster in BEC dark matter than in pressureless dark matter. Finally, we consider a "dark fluid" with a generalized equation of state p = (αρ + kρ 2 )c 2 having a component p = kρ 2 c 2 similar to BEC dark matter and a component p = αρc 2 mimicking the effect of the cosmological constant (dark energy). We find optimal parameters that give good agreement with the standard ΛCDM model that assumes a finite cosmological constant.

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Cold Bose stars

Cited by 104 publications

References 3 publications

Scrutinizing the pion condensed phase

Scrutinizing the pion condensed phase

Dynamical evolution of fermion-boson stars

Growth of perturbations in an expanding universe with Bose-Einstein condensate dark matter

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