Reionization in sterile neutrino cosmologies

Bose, Sownak; Frenk, Carlos S.; Hou, Jing; Lacey, Cedric G.; Lovell, Mark R.

doi:10.1093/mnras/stw2288

Cited by 41 publications

(63 citation statements)

References 113 publications

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“…but there is a sharp increase in the star formation rate in ETHOS haloes for M200 < 4 × 10 9 M . This is consistent with the scenario suggested in Bose et al (2016b) and Lovell et al (2018a), where haloes near the cutoff scale in models with a primordial power spectrum cutoff collapse later relative to CDM but do so more rapidly, thus producing a bright starburst. This is shown explicitly with the blue curve in Fig.…”

Section: Galaxy Propertiessupporting

confidence: 90%

ETHOS – an effective theory of structure formation: formation of the first haloes and their stars

Lovell

Zavala

Vogelsberger

2019

Monthly Notices of the Royal Astronomical Society

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A cutoff in the linear matter power spectrum at dwarf galaxy scales has been shown to affect the abundance, formation mechanism and age of dwarf haloes and their galaxies at high and low redshift. We use hydrodynamical simulations of galaxy formation within the ETHOS framework in a benchmark model that has such a cutoff, and that has been shown to be an alternative to the cold dark matter (CDM) model that alleviates its dwarf-scale challenges. We show how galaxies in this model form differently to CDM on a halo-by-halo basis, at redshifts z ≥ 6. We show that ETHOS haloes at the half-mode mass scale form with 50 per cent less mass than their CDM counterparts due to their later formation times, yet they retain more of their gas reservoir due to the different behaviour of gas and dark matter during the monolithic collapse of the first haloes in models with a galactic-scale cutoff. As a result, galaxies in ETHOS haloes near the cutoff scale grow rapidly between z = 10 − 6 and by z = 6 end up having very similar stellar masses, higher gas fractions and higher star formation rates relative to their CDM counterparts. We highlight these differences by making predictions for how the number of galaxies with old stellar populations is suppressed in ETHOS for both z = 6 galaxies and for gas-poor Local Group fossil galaxies. Interestingly, we find an age gradient in ETHOS between galaxies that form in high and low density environments.

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Section: Galaxy Propertiessupporting

confidence: 90%

ETHOS – an effective theory of structure formation: formation of the first haloes and their stars

Lovell

Zavala

Vogelsberger

2019

Monthly Notices of the Royal Astronomical Society

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“…The early structure formation in WDM models has been studied with semi-analytic models and numerical simulations (e.g. Yoshida et al 2003a;O'Shea & Norman 2006;Gao & Theuns 2007;Bose et al 2016;Dayal et al 2017;Lovell et al 2018Lovell et al , 2019. In cosmological hydrodynamic simulations for a WDM cosmology with a particle mass of mχc 2 = 3 keV, Yoshida et al (2003a) found that the formation of star forming clouds is delayed by ∼ 60 Myr, and suppressed in number by about two orders of magnitude, which leads to much less efficient early ionization of the IGM, compared with that in the CDM model calibrated to the initial WMAP data release.…”

Section: Early Structure Formationmentioning

confidence: 99%

Global radiation signature from early structure formation

Liu

Jaacks

Finkelstein

2019

Monthly Notices of the Royal Astronomical Society

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We use cosmological hydrodynamic zoom-in simulations to study early structure formation in two dark matter (DM) cosmologies, the standard CDM model, and a thermal warm DM (WDM) model with a particle mass of m χ c 2 = 3 keV. We focus on DM haloes with virial masses M ∼ 10 10 M . We find that the first star formation activity is delayed by ∼ 200 Myr in the WDM model, with similar delays for metal enrichment and the formation of the second generation of stars. However, the differences between the two models in globally-averaged properties, such as star formation rate density and mean metallicity, decrease towards lower redshifts (z 10). Metal enrichment in the WDM cosmology is restricted to dense environments, while low-density gas can also be significantly enriched in the CDM case. The free-free contribution from early structure formation at redshifts z > 6 to the cosmic radio background (CRB) is 3 +13 −1.5 % (8 +33 −3.5 %) of the total signal inferred from radio experiments such as ARCADE 2, in the WDM (CDM) model. The direct detection of the H 2 emission from early structure formation (z 7.2), originating from the low-mass haloes explored here, will be challenging even with the next generation of far-infrared space telescopes, unless the signal is magnified by at least a factor of 10 via gravitational lensing or shocks. However, more massive haloes with M 10 12 M may be observable for z 10, even without magnification, provided that our extrapolation from the scale of our simulated haloes is valid.

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“…Previous works have studied the effect of non-CDM models on the 21-cm signal [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Those models typically suppress the matter power spectrum beyond some wavenumber k, delaying the onset of cosmic dawn.…”

Section: Introductionmentioning

confidence: 99%

Probing the small-scale matter power spectrum with large-scale 21-cm data

2020

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The distribution of matter fluctuations in our universe is key for understanding the nature of dark matter and the physics of the early cosmos. Different observables have been able to map this distribution at large scales, corresponding to wavenumbers k 10 Mpc −1 , but smaller scales remain much less constrained. In this work we study the sensitivity of upcoming measurements of the 21-cm line of neutral hydrogen to the small-scale matter power spectrum. The 21-cm line is a promising tracer of early stellar formation, which took place in small haloes (with masses M ∼ 10 6 − 10 8 M ), formed out of matter overdensities with wavenumbers as large as k ≈ 100 Mpc −1 . Here we forecast how well both the 21-cm global signal, and its fluctuations, could probe the matter power spectrum during cosmic dawn (z = 12−25). In both cases we find that the long-wavelength modes (with k 40 Mpc −1 ) are highly degenerate with astrophysical parameters, whereas the modes with k = (40 − 80) Mpc −1 are more readily observable. This is further illustrated in terms of the principal components of the matter power spectrum, which peak at k ∼ 50 Mpc −1 both for a typical experiment measuring the 21-cm global signal and its fluctuations. We find that, imposing broad priors on astrophysical parameters, a global-signal experiment can measure the amplitude of the matter power spectrum integrated over k = (40−80) Mpc −1 with a precision of tens of percent. A fluctuation experiment, on the other hand, can constrain the power spectrum to a similar accuracy over both the k = (40 − 60) Mpc −1 and (60 − 80) Mpc −1 ranges even without astrophysical priors. The constraints outlined in this work would be able to test the behavior of dark matter at the smallest scales yet measured, for instance probing warm-dark matter masses up to mWDM = 8 keV for the global signal and 14 keV for the 21-cm fluctuations. This could shed light on the nature of dark matter beyond the reach of other cosmic probes.

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Reionization in sterile neutrino cosmologies

Cited by 41 publications

References 113 publications

ETHOS – an effective theory of structure formation: formation of the first haloes and their stars

ETHOS – an effective theory of structure formation: formation of the first haloes and their stars

Global radiation signature from early structure formation

Probing the small-scale matter power spectrum with large-scale 21-cm data

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