Háskóli ÍslandsUniversity of IcelandLovell, MarkZavala Franco, JesusVogelsberger, MarkShen, XuejianCyr-Racine, Francis-YanPfrommer, ChristophSigurdson, KrisBoylan-Kolchin, MichaelPillepich, Annalisa2018-12-052018-12-052018-03-28Lovell, M. R., Zavala, J., Vogelsberger, M., Shen, X., Cyr-Racine, F.-Y., Pfrommer, C., . . . Pillepich, A. (2018). ETHOS – an effective theory of structure formation: predictions for the high-redshift Universe – abundance of galaxies and reionization. Monthly Notices of the Royal Astronomical Society, 477(3), 2886-2899. doi:10.1093/mnras/sty8180035-87111365-2966 (eISSN)https://hdl.handle.net/20.500.11815/938Pre-print (óritrýnt handrit)We contrast predictions for the high-redshift galaxy population and reionization history between cold dark matter (CDM) and an alternative self-interacting dark matter model based on the recently developed ETHOS framework that alleviates the small-scale CDM challenges within the Local Group. We perform the highest resolution hydrodynamical cosmological simulations (a 36 Mpc3 volume with gas cell mass of ∼105M⊙ and minimum gas softening of ∼180 pc) within ETHOS to date – plus a CDM counterpart – to quantify the abundance of galaxies at high redshift and their impact on reionization. We find that ETHOS predicts galaxies with higher ultraviolet (UV) luminosities than their CDM counterparts and a faster build-up of the faint end of the UV luminosity function. These effects, however, make the optical depth to reionization less sensitive to the power spectrum cut-off: the ETHOS model differs from the CDM τ value by only 10 per cent and is consistent with Planck limits if the effective escape fraction of UV photons is 0.1–0.5. We conclude that current observations of high-redshift luminosity functions cannot differentiate between ETHOS and CDM models, but deep James Webb Space Telescope surveys of strongly lensed, inherently faint galaxies have the potential to test non-CDM models that offer attractive solutions to CDM's Local Group problems.2886-2899eninfo:eu-repo/semantics/openAccessGalaxiesDark matterVetrarbrautirStjarneðlisfræðiinfo:eu-repo/semantics/articleMonthly Notices of the Royal Astronomical Society10.1093/mnras/sty818