Axion as a cold dark matter candidate: Low-mass case

Park, Chan-Gyung; Hwang, Jai‐chan; Noh, Hyerim

doi:10.1103/physrevd.86.083535

Cited by 79 publications

(78 citation statements)

References 69 publications

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“…harmonic potential, oscillating coherently with a frequency much higher than the expansion rate behaves as CDM, at least at the background level. Afterwards, ultralight scalar fields have been thoroughly studied at the perturbation level [15][16][17][18][19], proving that the same conclusion holds. Perturbations of coherent oscillating scalar fields admit an effective fluid description with an effective sound speed nearly zero, like CDM.…”

Section: Jhep08(2018)073mentioning

confidence: 67%

Constraints on anharmonic corrections of fuzzy dark matter

Cembranos

Maroto

Jareño

et al. 2018

J. High Energ. Phys.

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The cold dark matter (CDM) scenario has proved successful in cosmology. However, we lack a fundamental understanding of its microscopic nature. Moreover, the apparent disagreement between CDM predictions and subgalactic-structure observations has prompted the debate about its behaviour at small scales. These problems could be alleviated if the dark matter is composed of ultralight fields m ∼ 10 −22 eV, usually known as fuzzy dark matter (FDM). Some specific models, with axion-like potentials, have been thoroughly studied and are collectively referred to as ultralight axions (ULAs) or axion-like particles (ALPs). In this work we consider anharmonic corrections to the mass term coming from a repulsive quartic self-interaction. Whenever this anharmonic term dominates, the field behaves as radiation instead of cold matter, modifying the time of matter-radiation equality. Additionally, even for high masses, i.e. masses that reproduce the cold matter behaviour, the presence of anharmonic terms introduce a cut-off in the matter power spectrum through its contribution to the sound speed. We analyze the model and derive constraints using a modified version of class and comparing with CMB and large-scale structure data.

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Section: Jhep08(2018)073mentioning

confidence: 67%

Constraints on anharmonic corrections of fuzzy dark matter

Cembranos

Maroto

Jareño

et al. 2018

J. High Energ. Phys.

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“…Similar ideas were independently investigated by many authors [23,[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][40][41][42][43][44][45]. For example, a model with m = 0 was suggested in [27], which has a stability issue.…”

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confidence: 77%

“…Guzman and Matos et al [46,47] extensively studied various astrophysical aspects of the SFDM. Other attempts are based, for example, on a non-minimal coupling [28], quintessence [29,48], Repulsive DM [30], fluid DM [32], nontopological soliton [33], cosh potential [35,36], and ULA [34,37,38] among many [39][40][41][42][43][44]49]. The BEC nature of this DM was extensively studied in [9,23,50] by Harko, Chavanis and their colleagues.…”

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confidence: 99%

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Brief History of Ultra-light Scalar Dark Matter Models

Lee

2018

EPJ Web Conf.

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Abstract. This is a review on the brief history of the scalar field dark matter model also known as fuzzy dark matter, BEC dark matter, wave dark matter, or ultra-light axion. In this model ultra-light scalar dark matter particles with mass m = O(10 −22 )eV condense in a single Bose-Einstein condensate state and behave collectively like a classical wave. Galactic dark matter halos can be described as a self-gravitating coherent scalar field configuration called boson stars. At the scale larger than galaxies the dark matter acts like cold dark matter, while below the scale quantum pressure from the uncertainty principle suppresses the smaller structure formation so that it can resolve the small scale crisis of the conventional cold dark matter model.Despite long efforts dark matter (DM) remains a great mystery in physics and astronomy [1]. While numerical results of the cold dark matter (CDM) model are remarkably successful in explaining the large scale structure of the universe, it encounters some problems at the scale of galactic or sub-galactic structures. For example, the numerical simulations usually predict cusped central halo density and too many sub-halos and small galaxies, which seem to be in contradiction with observations [2][3][4][5].Recently, there is a growing interest in the idea that DM particles are ultra-light scalars in Bose-Einstein condensate (BEC). (For a review, see Refs. 6-13) In this model, due to the tiny DM particle mass m = O(10 −22 )eV, the DM particle number density is very high and hence the inter-particle distance is much smaller than the de Broglie wave length of the DM particles. Therefore, the particles are in BEC and move collectively as a wave rather than incoherent particles. At the scale larger than galaxies the DM perturbation behaves like that of CDM, while below the scale quantum pressure from the uncertainty principle suppresses the small structure formation, which makes it a viable alternative to CDM. This property helps us to resolve the small scale problems of the CDM model such as the missing satellite problem or the cusp/core problem [14].Before 2000 there were only a few groups of scientists working on this topic, without much communication even between them. Being unaware of precedent works, many researchers in this field independently proposed similar ideas with various names such as BEC DM, scalar field DM (SFDM), fuzzy DM, ultra-light axion (ULA), ultralight axion like particle (ALP), wave DM, ψ DM, repulsive DM or (super)fluid DM among many, although the basic physics of these models is quite similar. (Henceforth, I will use the term 'SFDM' for the model.) This unfortunate ⋆ e-mail: scikid@jwu.ac.kr situation has brought some confusions among researchers in this field. Therefore, at this point, it is desirable to summarize what have already attempted in this exciting field. 1The hypothesis that galactic DMs are ultra-light scalar particles in BEC has a long history. In Ref.[15] Baldeschi et al. considered the galactic halo model of self-gravitating bosons wit...

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“…Thus the general analysis of the behaviour of these scalar field models at the background level was developed in [42] and the study of its perturbations can be found in [48][49][50][51][52] for massive scalars and [53] for a generic power-law potential. However, in principle, the scenario could be also implemented for any bosonic field.…”

Section: Jhep02(2017)064mentioning

confidence: 99%

Perturbations of ultralight vector field dark matter

Cembranos

Maroto

Jareño

2017

J. High Energ. Phys.

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Abstract:We study the dynamics of cosmological perturbations in models of dark matter based on ultralight coherent vector fields. Very much as for scalar field dark matter, we find two different regimes in the evolution: for modes with k 2 Hma, we have a particle-like behaviour indistinguishable from cold dark matter, whereas for modes with k 2Hma, we get a wave-like behaviour in which the sound speed is non-vanishing and of order c 2 s k 2 /m 2 a 2 . This implies that, also in these models, structure formation could be suppressed on small scales. However, unlike the scalar case, the fact that the background evolution contains a non-vanishing homogeneous vector field implies that, in general, the evolution of the three kinds of perturbations (scalar, vector and tensor) can no longer be decoupled at the linear level. More specifically, in the particle regime, the three types of perturbations are actually decoupled, whereas in the wave regime, the three vector field perturbations generate one scalar-tensor and two vector-tensor perturbations in the metric. Also in the wave regime, we find that a non-vanishing anisotropic stress is present in the perturbed energy-momentum tensor giving rise to a gravitational slip of order (Φ − Ψ)/Φ ∼ c 2 s . Moreover in this regime the amplitude of the tensor to scalar ratio of the scalar-tensor modes is also h/Φ ∼ c 2 s . This implies that small-scale density perturbations are necessarily associated to the presence of gravity waves in this model. We compare their spectrum with the sensitivity of present and future gravity waves detectors.

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Axion as a cold dark matter candidate: Low-mass case

Cited by 79 publications

References 69 publications

Constraints on anharmonic corrections of fuzzy dark matter

Constraints on anharmonic corrections of fuzzy dark matter

Brief History of Ultra-light Scalar Dark Matter Models

Perturbations of ultralight vector field dark matter

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