21-cm observations and warm dark matter models

Boyarsky, Alexey; Iakubovskyi, Dmytro; Ruchayskiy, Oleg; Rudakovskyi, Anton; Valkenburg, Wessel

doi:10.1103/physrevd.100.123005

Cited by 32 publications

(39 citation statements)

References 108 publications

(150 reference statements)

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“…4 https://bitbucket.org/franyancr/ethos_camb Note that our constraints would be weaker if f * was allowed to be higher. Nonetheless, while f * can fluctuate by orders of magnitude from one galaxy to another, reaching values near unity [26], the observed f * is the average over all star-forming galaxies, and thus should not be close to unity. Additionally, we caution the reader that our ETHOS constraint is only approximate, as the sharp-k filter employed here can fail to reproduce the halo mass function form simulations in cases with DAOs [116].…”

Section: E Edges Datamentioning

confidence: 91%

“…Here, as in Refs. [22][23][24][25][26][27]39], we take advantage of this lower bound on the amount of Lyman-α photons to probe different dark-matter models. We will phrase the EDGES requirement in terms of the dimensionless coupling coefficient x α , which enters in the definition of the spin temperature (ignoring collisional coupling during cosmic dawn) as…”

Section: E Edges Datamentioning

confidence: 99%

“…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%

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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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Section: E Edges Datamentioning

confidence: 91%

Section: E Edges Datamentioning

confidence: 99%

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

2020

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“…The timing of the EDGES signal constrains λ d : too much suppression delays structure formation and hence the Lyman-α background also builds up too late [26,[78][79][80][81][82]. Here we re-examine this constraint.…”

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confidence: 94%

Constraining structure formation using EDGES

Leo

Theuns

Baugh

et al. 2020

J. Cosmol. Astropart. Phys.

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The experiment to detect the global epoch of reionization signature (EDGES) collaboration reported the detection of a line at 78 MHz in the sky-averaged spectrum due to neutral hydrogen (HI) 21-cm hyperfine absorption of cosmic microwave background (CMB) photons at redshift z ∼ 17. This requires that the spin temperature of HI be coupled to the kinetic temperature of the gas at this redshift through the scattering of Lyman-α photons emitted by massive stars. To explain the experimental result, star formation needs to be sufficiently efficient at z ∼ 17 and this can be used to constrain models in which small-scale structure formation is suppressed (DMF models), either due to dark matter free-streaming or non-standard inflationary dynamics. We combine simulations of structure formation with a simple recipe for star formation to investigate whether these models emit enough Lyman-α photons to reproduce the experimental signal for reasonable values of the star formation efficiency, f . We find that a thermal warm dark matter (WDM) model with mass m WDM ∼ 4.3 keV is consistent with the timing of the signal for f 2%. The exponential growth of structure around z ∼ 17 in such a model naturally generates a sharp onset of the absorption. A warmer model with m WDM ∼ 3 keV requires a higher star formation efficiency, f ∼ 6%, which is a factor of few above predictions of current star formation models and observations of satellites in the Milky Way. However, uncertainties in the process of star formation at these redshifts do not allow to derive strong constrains on such models using 21-cm absorption line. The onset of the 21-cm absorption is generally slower in DMF than observed in cold dark matter (CDM) models, unless some process significantly suppresses star formation in halos with circular velocity below ∼ 20 km s −1 . arXiv:1909.04641v1 [astro-ph.CO]

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“…Complementary constraints in this mass range can come from pulsar-timing arrays [15,16]. Yet higher masses can be probed by the dynamics of star clusters [17] or the spec- * diego.blas@cern.ch † dnacir@df.uba.ar ‡ sergey.sibiryakov@cern.ch tral shape of 21-cm absorption feature [18,19] (see [20] for the discussion of the robustness of 21-cm bounds). Finally, ULDM masses up to m Φ ∼ 10 −18 eV might be explored using 21-cm intensity mapping [21].…”

Section: Introductionmentioning

confidence: 99%

Secular effects of ultralight dark matter on binary pulsars

2020

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Dark matter (DM) can consist of very light bosons behaving as a classical scalar field that experiences coherent oscillations. The presence of this DM field would perturb the dynamics of celestial bodies, either because the (oscillating) DM stress tensor modifies the gravitational potentials of the galaxy, or if DM is directly coupled to the constituents of the body. We study secular variations of the orbital parameters of binary systems induced by such perturbations. Two classes of effects are identified. Effects of the first class appear if the frequency of DM oscillations is in resonance with the orbital motion; these exist for general DM couplings including the case of purely gravitational interaction. Effects of the second class arise if DM is coupled quadratically to the masses of the binary system members and do not require any resonant condition. The exquisite precision of binary pulsar timing can be used to constrain these effects. Current observations are not sensitive to oscillations in the galactic gravitational field, though a discovery of pulsars in regions of high DM density may improve the situation. For DM with direct coupling to ordinary matter, the current timing data are already competitive with other existing constraints in the range of DM masses ∼ 10 −22 − 10 −18 eV. Future observations are expected to increase the sensitivity and probe new regions of parameters.

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21-cm observations and warm dark matter models

Cited by 32 publications

References 108 publications

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

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

Constraining structure formation using EDGES

Secular effects of ultralight dark matter on binary pulsars

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