Gravitational instability of scalar fields and formation of primordial black holes

Khlopov, Maxim Yu.; Malomed, B. A.; Zel’dovich, Ya. B.

doi:10.1093/mnras/215.4.575

Cited by 497 publications

(400 citation statements)

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“…It is more difficult to find particle-physics models in this case [46], but the model is nonetheless well motivated as the simplest modification leading to a stable potential. This modification has been previously analyzed in some works [47][48][49][50][51][52]. The additional source of pressure from the repulsive self-interactions helps to solve the 'corecusp' problem with larger masses [46].…”

Section: Jhep08(2018)073mentioning

confidence: 99%

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: 99%

Constraints on anharmonic corrections of fuzzy dark matter

Cembranos

Maroto

Jareño

et al. 2018

J. High Energ. Phys.

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“…This property alleviates the small scale problems of the CDM model [32,35,56,59]. Equating c 2 q k 2 with 4πGρ gives the quantum Jeans length scale [31,60,61] at the redshift z,…”

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confidence: 93%

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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“…This subject has been mainly JHEP03(2016)013 studied for harmonic potential models that mimic the standard dark matter case [65][66][67][68][69][70][71], as it happens for the axion field [72,73]. It has been proved by using the linear perturbation theory that the axion was equivalent to CDM for high enough masses [74][75][76][77].…”

Section: Introductionmentioning

confidence: 99%

Cosmological perturbations in coherent oscillating scalar field models

Cembranos

Maroto

Jareño

2016

J. High Energ. Phys.

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The fact that fast oscillating homogeneous scalar fields behave as perfect fluids in average and their intrinsic isotropy have made these models very fruitful in cosmology. In this work we will analyse the perturbations dynamics in these theories assuming general power law potentials V (φ) = λ|φ| n /n. At leading order in the wavenumber expansion, a simple expression for the effective sound speed of perturbations is obtained c 2 eff = ω = (n − 2)/(n + 2) with ω the effective equation of state. We also obtain the first order correction in k 2 /ω 2 eff , when the wavenumber k of the perturbations is much smaller than the background oscillation frequency, ω eff . For the standard massive case we have also analysed general anharmonic contributions to the effective sound speed. These results are reached through a perturbed version of the generalized virial theorem and also studying the exact system both in the super-Hubble limit, deriving the natural ansatz for δφ; and for sub-Hubble modes, exploiting Floquet's theorem.

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Gravitational instability of scalar fields and formation of primordial black holes

Cited by 497 publications

References 0 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

Cosmological perturbations in coherent oscillating scalar field models

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