What is the Halo Mass Function in a Fuzzy Dark Matter Cosmology?

Kulkarni, Mihir; Ostriker, Jeremiah P.

doi:10.48550/arxiv.2011.02116

Cited by 8 publications

(9 citation statements)

References 40 publications

(87 reference statements)

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“…These bounds assume (1) star formation tracking halo formation, and (2) an upper limit on the fraction of halo baryons that turn into stars (0.05 in Lidz & Hui 2018). Another important assumption is that the halo mass function can be reliably predicted from the linear power spectrum by the standard Press-Schechter or Sheth-Tormen relations (Press & Schechter 1974, Sheth & Tormen 1999, Marsh & Silk 2014, Kulkarni & Ostriker 2020. 36 These relations have been checked for fuzzy dark matter models using only N-body, as opposed to wave, simulations, i.e.…”

Section: Linear Power Spectrum and Early Structure Formationmentioning

confidence: 99%

Wave Dark Matter

Hui

2021

Preprint

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We review the physics and phenomenology of wave dark matter: a bosonic dark matter candidate lighter than about 30 eV. Such particles have a de Broglie wavelength exceeding the average inter-particle separation in a galaxy like the Milky Way, thus well described as a set of classical waves. We outline the particle physics motivations for them, including the QCD axion as well as ultra-light axion-like-particles such as fuzzy dark matter. The wave nature of the dark matter implies a rich phenomenology:• Wave interference gives rise to order unity density fluctuations on de Broglie scale in halos. One manifestation is vortices where the density vanishes and around which the velocity circulates. There is one vortex ring per de Broglie volume on average. • For sufficiently low masses, soliton condensation occurs at centers of halos. The soliton oscillates and random walks, another manifestation of wave interference. The halo and subhalo abundance is expected to be suppressed at small masses, but the precise prediction from numerical wave simulations remains to be determined. • For ultra-light ∼ 10 −22 eV dark matter, the wave interference substructures can be probed by tidal streams/gravitational lensing. The signal can be distinguished from that due to subhalos by the dependence on stream orbital radius/image separation. • Axion detection experiments are sensitive to interference substructures for wave dark matter that is moderately light. The stochastic nature of the waves affects the interpretation of experimental constraints and motivates the measurement of correlation functions.Current constraints and open questions, covering detection experiments and cosmological/galactic/black-hole observations, are discussed.

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Section: Linear Power Spectrum and Early Structure Formationmentioning

confidence: 99%

Wave Dark Matter

Hui

2021

Preprint

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“…We can expect the subhalo abundance to be suppressed at least as strongly as the abundance of iso-lated halos is suppressed. For m ∼ 10 −22 eV, the halo mass function is suppressed below M J 10 10 M , and for other FDM masses the suppression scale is expected to behave as M J ∝ m −3/2 [42,49]. Therefore, we can expect significant suppression of subhalos below mass M 10 9 −10 10 M for the FDM parameters we have considered.…”

Section: Discussionmentioning

confidence: 97%

Don't cross the streams: caustics from Fuzzy Dark Matter

Dalal,

Bovy,

Hui

et al. 2020

Preprint

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We study how tidal streams from globular clusters may be used to constrain the mass of ultra-light dark matter particles, called 'fuzzy' dark matter (FDM). A general feature of FDM models is the presence of ubiquitous density fluctuations in bound, virialized dark matter structures, on the scale of the de Broglie wavelength, arising from wave interference in the evolving dark matter distribution. These time-varying fluctuations can disturb the motions of stars, leading to potentially observable signatures in cold thin tidal streams in our own Galaxy. The study of this effect has been hindered by the difficulty in simulating the FDM wavefunction in Milky Way-sized systems. We present a simple method to evolve realistic wavefunctions in nearly static potentials, that should provide an accurate estimate of this granulation effect. We quantify the impact of FDM perturbations on tidal streams, and show that initially, while stream perturbations are small in amplitude, their power spectra exhibit a sharp cutoff corresponding to the de Broglie wavelength of the FDM potential fluctuations. Eventually, when stream perturbations become nonlinear, fold caustics generically arise that lead to density fluctuations with universal behavior. This erases the signature of the de Broglie wavelength in the stream density power spectrum, but we show that it will still be possible to determine the FDM mass in this regime, by considering the fluctuations in quantities like angular momenta or actions.

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“…Note that the Jeans mass M J for ULA cosmologies is proportional to m −3/2 a [32,[103][104][105][106][107][108]. Different approaches to achieve this exist [44,109,110]. They all have in common that there are no significant effects on the mass function for halo masses above 10 11 h −1 M .…”

Section: Modelling Galaxy Cluster Counts In the Presence Of Ultra-lig...mentioning

confidence: 99%

Constraining Ultra-light Axions with Galaxy Cluster Number Counts

Diehl,

Weller

2021

Preprint

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In this paper we investigate the potential of current and upcoming cosmological surveys to constrain the mass and abundance of ultra-light axion (ULA) cosmologies with galaxy cluster number counts. ULAs, sometimes also referred to as Fuzzy Dark Matter, are well-motivated in many theories beyond the Standard Model and could potentially solve the ΛCDM small-scale crisis. Galaxy cluster counts provide a robust probe of the formation of structures in the Universe. Their distribution in mass and redshift is strongly sensitive to the underlying linear matter perturbations. In this forecast paper we explore two scenarios, firstly an exclusion limit on axion mass given a no-axion model and secondly constraints on an axion model. With this we obtain lower limits on the ULA mass on the order of m a 10 −24 eV. However, this result depends heavily on the mass of the smallest reliably observable clusters for a given survey. Cluster counts, like many other cosmological probes, display an approximate degeneracy in the ULA mass vs. abundance parameter space, which is dependent on the characteristics of the probe. These degeneracies are different for other cosmological probes. Hence galaxy cluster counts might provide a complementary window on the properties of ultra-light axions.

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What is the Halo Mass Function in a Fuzzy Dark Matter Cosmology?

Cited by 8 publications

References 40 publications

Wave Dark Matter

Wave Dark Matter

Don't cross the streams: caustics from Fuzzy Dark Matter

Constraining Ultra-light Axions with Galaxy Cluster Number Counts

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