Testing extreme-axion wave dark matter using the BOSS Lyman-Alpha forest data

Ka-Hou Leong; Hsi-Yu Schive; Ui-Han Zhang; Tzihong Chiueh

doi:10.1093/mnras/stz271

paper

Testing extreme-axion wave dark matter using the BOSS Lyman-Alpha forest data

arXiv:1810.05930 · doi:10.1093/mnras/stz271

Abstract

Using cosmological particle hydrodynamical simulations and uniform ultraviolet backgrounds, we compare Lyman- $α$ forest flux spectra predicted by the conventional cold dark matter (CDM) model, the free-particle wave dark matter (FP $ψ$ DM) model and extreme-axion wave dark matter (EA $ψ$ DM) models of different initial axion field angles against the BOSS Lyman- $α$ forest absorption spectra with a fixed boson mass $m_{b} \sim 1 0^{- 22}$ eV. We recover results reported previously (Iršič et al. 2017b; Armengaud et al. 2017) that the CDM model agrees better with the BOSS data than the FP $ψ$ DM model by a large margin, and we find the difference of total $χ^{2}$ 's is $120$ for $420$ data bins. These previous results demand a larger boson mass by a factor $> 10$ to be consistent with the date and are in tension with the favoured value determined from local satellite galaxies. We however find that such tension is removed as some EA $ψ$ DM models predict Lyman- $α$ flux spectra agreeing better with the BOSS data than the CDM model, and the difference of total $χ^{2}$ 's can be as large as $24$ for the same bin number. This finding arises with no surprise since EA $ψ$ DM models have unique spectral shapes with spectral bumps in excess of the CDM power near the small-scale cutoff typical of $ψ$ DM linear matter power spectra as well as more extended cutoffs than FP $ψ$ DM (Zhang & Chiueh 2017a,b).

Testing extreme-axion wave dark matter using the BOSS Lyman-Alpha forest data

Abstract

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