First Constraints on Fuzzy Dark Matter from Lyman- α Forest Data and Hydrodynamical Simulations

Abstract

We present constraints on the masses of extremely light bosons dubbed fuzzy dark matter from Lyman-α forest data. Extremely light bosons with a De Broglie wavelength of ∼ 1 kpc have been suggested as dark matter candidates that may resolve some of the current small scale problems of the cold dark matter model. For the first time we use hydrodynamical simulations to model the Lyman-α flux power spectrum in these models and compare with the observed flux power spectrum from two different data sets: the XQ-100 and HIRES/MIKE quasar spectra samples. After marginalization over nuisance and physical parameters and with conservative assumptions for the thermal history of the IGM that allow for jumps in the temperature of up to 5000 K, XQ-100 provides a lower limit of 7.1×10 −22 eV, HIRES/MIKE returns a stronger limit of 14.3×10 −22 eV, while the combination of both data sets results in a limit of 20 ×10 −22 eV (2σ C.L.). The limits for the analysis of the combined data sets increases to 37.5×10 −22 eV (2σ C.L.) when a smoother thermal history is assumed where the temperature of the IGM evolves as a power-law in redshift. Light boson masses in the range 1 − 10 × 10 −22 eV are ruled out at high significance by our analysis, casting strong doubts that FDM helps solve the "small scale crisis" of the cold dark matter models.Introduction. Recently, there has been a growing interest in so-called Fuzzy Dark Matter (FDM) models where the dark matter is made of ultra-light bosons. Cosmological and astrophysical consequences have been comprehensively reviewed in [1-5] highlighting the particle physics motivation [6-9] for such models, as well as the importance of experimental searches [10]. A broad variety of astrophysical implications have been investigated in the literature: the halo mass function [11], the innermost structure of haloes [12][13][14], the dynamical properties of the smallest objects [15], the linear matter power spectrum [1], the development of non-linearities by using N-body simulations [16], the abundance of high redshift objects [17], the overall impact of FDM on galaxy formation and the reionization history of the Universe, the intergalactic medium [4,[18][19][20][21], pulsar timing and binary pulsars [22,23], and the properties of our galactic disk [24]. The general conclusion is that in order to have an

Cosmological perturbations of extreme axion in the radiation era

“…We call this singular case the extreme axion model. This narrow window of new degree of freedom is interesting, and may allows for accommodating the tension concerning the particle mass of ψDM determined by the highredshift Lyman-α forests [21,22] and by the flat cores of nearby dwarf spheroid galaxies [13,23,24]. In this work, we follow up this finding of Paper (I) for the extreme axion model and analyze the perturbation evolution in details.…”

“…Therefore, the high-k power spectrum may not be a good indicator accurately reflecting the true particle mass in the extreme axion model. Recent simulations addressing the high-redshift Lyman-α absorption features indicate that substantially higher particle mass than 10 −22 eV is required or implied [21,22]. On the other hand, approximately 10 −22 eV particle mass is needed to account for the flat cores of dwarf spheroidal galaxies [11,13].…”

“…Recently there have been numerical works attempting to address axion perturbations [28], partly motivated by string theories [16,17,19] and partly by the emerging interest in wave dark matter [11,13,18,21,22,[29][30][31][32]. The difficulty of computing axion perturbations arises from that the equation demands high numerical accuracy to solve, as it must stably track two near-by-frequency oscillations for thousands of, or even much more, periods to determine the precise relative phase shift between the two oscillations.…”

Unbiased constraints on ultralight axion mass from dwarf spheroidal galaxies

“…The strongest constraints on any possible suppression of clustering power relative to CDM are found from the Lyman-α forest flux power spectrum. Recently, two groups have performed Lyman-α simulations with ULAs, finding the constraints m22 20 − 30, depending on the exact combination of data used (Armengaud et al 2017;Iršič et al 2017). It is important to note, however, that Lyman-α constraints depend strongly on the modelling of the temperature of the intergalactic medium, and in particular can be loosened if the evolution is non-monotonic (Garzilli et al 2015;Hui et al 2017).…”

Brief History of Ultra-light Scalar Dark Matter Models

“…By fitting RCs one can obtain the scalar field mass m ∼ 10 −22 eV, and interestingly the SFDM with this mass range can resolve many of the small scale problems of CDM models. One exception is the Lyman alpha tension [79,80] which is under debate [81]. This EPJ Web of Conferences 168, 06005 (2018) https://doi.org/10.1051/epjconf/201816806005 Joint International Conference of ICGAC-XIII and IK-15 on Gravitation, Astrophysics and Cosmology model can be used to explain the puzzling minimum mass scale [63,64] and the minimum length scale of galaxies [82,83] regardless of their luminosity [84] and the observed size evolution [62] of the most massive galaxies [85][86][87].…”