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Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/6447
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dc.contributor.authorSarkar, Abir-
dc.contributor.authorMondal, Rajesh-
dc.contributor.authorDas, Subinoy-
dc.contributor.authorSethi, S.K.-
dc.contributor.authorBharadwaj, Somnath-
dc.contributor.authorMarsh, David J E-
dc.date.accessioned2016-10-18T07:12:12Z-
dc.date.available2016-10-18T07:12:12Z-
dc.date.issued2016-04-
dc.identifier.citationJournal of Cosmology and Astroparticle Physics, 2016, Vol.04, p012en_US
dc.identifier.issn1475-7516 (Online)-
dc.identifier.urihttp://hdl.handle.net/2289/6447-
dc.descriptionRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)en_US
dc.description.abstractThe particle nature of dark matter remains a mystery. In this paper, we consider two dark matter models—Late Forming Dark Matter (LFDM) and Ultra-Light Axion (ULA) models—where the matter power spectra show novel effects on small scales. The high redshift universe offers a powerful probe of their parameters. In particular, we study two cosmological observables: the neutral hydrogen (HI) redshifted 21-cm signal from the epoch of reionization, and the evolution of the collapsed fraction of HI in the redshift range 2 < z < 5. We model the theoretical predictions of the models using CDM-like N-body simulations with modified initial conditions, and generate reionization fields using an excursion set model. The N-body approximation is valid on the length and halo mass scales studied. We show that LFDM and ULA models predict an increase in the HI power spectrum from the epoch of reionization by a factor between 2–10 for a range of scales 0.1 < k < 4 Mpc−1. Assuming a fiducial model where a neutral hydrogen fraction bar xHI = 0.5 must be achieved by z = 8, the reionization process allows us to put approximate bounds on the redshift of dark matter formation zf > 4 × 105 (for LFDM) and the axion mass ma > 2.6 × 10−23 eV (for ULA). The comparison of the collapsed mass fraction inferred from damped Lyman-α observations to the theoretical predictions of our models lead to the weaker bounds: zf > 2 × 105 and ma > 10−23 eV. These bounds are consistent with other constraints in the literature using different observables; we briefly discuss how these bounds compare with possible constraints from the observation of luminosity function of galaxies at high redshifts. In the case of ULAs, these constraints are also consistent with a solution to the cusp-core problem of CDM.en_US
dc.language.isoenen_US
dc.publisherIOP Publishing and SISSAen_US
dc.relation.urihttp://adsabs.harvard.edu/abs/2016JCAP...04..012Sen_US
dc.relation.urihttp://arxiv.org/abs/1512.03325en_US
dc.relation.urihttp://dx.doi.org/10.1088/1475-7516/2016/04/012en_US
dc.rights2016 IOP Publishing and SISSAen_US
dc.titleThe effects of the small-scale DM power on the cosmological neutral hydrogen (Hi) distribution at high redshiftsen_US
dc.typeArticleen_US
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