Acoustic modes of pulsating axion stars: Nonradial oscillations

Panotopoulos, Grigoris; Lopes, Ilídio

doi:10.1142/s0218271819501116

Cited by 5 publications

(4 citation statements)

References 79 publications

(89 reference statements)

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“…These are puzzling theoretical objects, predicted by some light dark-matter models, where Bose-Einstein condensate of axions is supposed to originate self-gravitant axion spheres, called axion stars. The theoretical non-radial pulsation power spectrum, originated by the tidal distorsion of the axion star due to a neutron star companion has been calculated in a recent paper (Panotopoulos and Lopes, 2019). This spectrum is derived assuming well-known asteroseismic model, compatible with the equation of state of the axion star, and should be characteristic of this kind of object.…”

Section: Degenerate Stars and New Hypothetical Objectsmentioning

confidence: 99%

“…The ongoing and future space missions, and surveys of pulsating stars, open a promising opportunity for Asteroseismology, in order to impose more accurate constraints on several dark matter models, improving the previous asteroseismic bounds derived from main sequence (Cadamuro and Redondo, 2010;Lopes and Silk, 2012;Turck-Chièze and Lopes, 2012;Redondo and Raffelt, 2013;Vinyoles et al, 2015) and evolved stars (Lopes et al, 2019;Ayala et al, 2020), as well as in WDs (Córsico et al, 2019(Córsico et al, , 2001. In addition, some theoretical predictions about the pulsations of exotic stellar objects, composed of dark matter, could be tested by means of future observations (Panotopoulos and Lopes, 2019;Lopes and Panotopoulos, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Looking into dark matter with asteroseismology

Ayala

2022

Front. Astron. Space Sci.

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Dark matter remains as an elusive component of modern Cosmology. According to previous research, stellar physics observables can be affected by the presence of hypothetical dark matter particles, which can be produced or accreted into the stars. Stellar pulsations are among the observables affected by dark matter, because the changes of the internal structure of the stars due to dark matter produce variations in the pulsation frequencies. We review the current research in the interplay between astroparticles, precise stellar observations, and accurate asteroseismic models, which can be extremely useful in order to constrain dark matter candidates from asteroseismic observables.

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Section: Degenerate Stars and New Hypothetical Objectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Looking into dark matter with asteroseismology

Ayala

2022

Front. Astron. Space Sci.

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“…The most recent upper limit obtained CAST fixed the upper limit of the axion-photon coupling in 6.6 10 −11 GeV −1 at 95% confidence level [1]. The production and existence of axions has been suggested in many cosmological and astrophysical contexts, such as pure axion stars and hybrid axion stars [i.e., 22,65,91], to mention a few. In some scenarios, the gravitational field of a recently formed axion star can capture neutral hydrogen leading to the appearance of a hypothetical mix of stars [12].…”

Section: Axion Motivation In Particle Physics and Astrophysicsmentioning

confidence: 99%

Axion spectra and the associated x-ray spectra of low-mass stars

Lopes

2021

Preprint

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Axion particles are among the best candidates to explain dark matter and resolve the strong CP problem in the Standard Model. If such a particle exists, the core of stars will produce them in large amounts. For the first time, we predict the axion spectra and their associated luminosities for several low-mass stars -one and two solar masses stars in the main sequence and post-main sequence stages of evolution. Equally, we also compute the x-ray excess emission resulting from the conversion of axions back to photons in the presence of a strong magnetic field in the envelope of these stars. Hence, a given star will have a unique axion spectrum and La axion luminosity. And if such star has a strong magnetic field in its stellar envelope, it will also show a characteristic x-ray spectrum and Laγ x-ray luminosity. Such radiation will add up to the x-ray electromagnetic spectrum and LX luminosity of the star. The present study focuses on axion models with an axion-photon coupling constant, 5 10 −11 GeV −1 , a value just below the most recent upper limit of 6.6 10 −11 GeV −1 found by CAST and IAXO helioscopes. The range of axion parameters discussed here spans many axion models' parameter space, including the DFSZ and KSVZ models. We found that axions with a mass in the range 10 −7 to 10 −5 eV and an axion-photon coupling constant of 5 10 −11 GeV −1 produce an axion emission spectra with an averaged axion energy that varies from 1 to 5 KeV, and an La ranging from 10 −6 to 7 10 −3 L⊙. We also predict that Laγ varies from 5 10 −8 to 10 −5 L⊙ for stars with an averaged magnetic field of 3 10 4 G in their atmospheres. Most of these Laγ predictions are larger than the LX observed in some stars. Therefore, such preliminary results show the potential of the next generation of stellar x-ray missions to constrain several classes of axion models.

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“…In the dilute case, the field value is small, self interactions are negligible, and the axion self-gravity is balanced by the kinetic pressure, while the self interactions can be treated perturbatively [34][35][36][37][38]. One can also seek denser solutions that are subject to strong non-linear and relativistic effects [39][40][41], which are however unstable and might be short lived [42][43][44][45][46]. In this work we only consider the former possibility of dilute boson stars.…”

Section: Introductionmentioning

confidence: 99%

Searching for Earth/Solar axion halos

Banerjee

Budker

Eby

et al. 2020

J. High Energ. Phys.

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We discuss the sensitivity of the present and near-future axion dark matter experiments to a halo of axions or axion-like particles gravitationally bound to the Earth or the Sun. Such halos, assuming they are formed, can be searched for in a wide variety of experiments even when the axion couplings to matter are small, while satisfying all the present experimental bounds on the local properties of dark matter. The structure and coherence properties of these halos also imply novel signals, which can depend on the latitude or orientation of the detector. We demonstrate this by analyzing the sensitivity of several distinct types of axion dark matter experiments.

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Acoustic modes of pulsating axion stars: Nonradial oscillations

Abstract: We compute the lowest frequency non-radial oscillation modes of dilute axion stars. The effective potential that enters into the Schrödinger-like equation, several associated eigenfunctions, and the large as well as the small frequency separations are shown as well.

Cited by 5 publications

References 79 publications

Looking into dark matter with asteroseismology

Looking into dark matter with asteroseismology

Axion spectra and the associated x-ray spectra of low-mass stars

Searching for Earth/Solar axion halos

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