Closing the window on fuzzy dark matter with the 21-cm signal

We search for ultra-light axions as dark matter (DM) and dark energy particle candidates, for axion masses 10-32 eV ≤ m a ≤ 10-24 eV, by a joint analysis of cosmic microwave background (CMB) and galaxy clustering data — and consider if axions can resolve the tension in inferred values of the matter clustering parameter S 8. We give legacy constraints from Planck 2018 CMB data, improving 2015 limits on the axion density Ωa h 2 by up to a factor of three; CMB data from the Atacama Cosmology Telescope and the South Pole Telescope marginally weaken Planck bounds at m a = 10-25 eV, owing to lower (and theoretically-consistent) gravitational lensing signals. We jointly infer, from Planck CMB and full-shape galaxy power spectrum and bispectrum data from the Baryon Oscillation Spectroscopic Survey (BOSS), that axions are, today, < 10% of the DM for m a ≤ 10-26 eV and < 1% for 10-30 eV ≤ m a ≤ 10-28 eV. BOSS data strengthen limits, in particular at higher m a by probing high-wavenumber modes (k < 0.4h Mpc-1). BOSS alone finds a preference for axions at 2.7σ, for m a = 10-26 eV, but Planck disfavours this result. Nonetheless, axions in a window 10-28 eV ≤ m a ≤ 10-25 eV can improve consistency between CMB and galaxy clustering data, e.g., reducing the S 8 discrepancy from 2.7σ to 1.6σ, since these axions suppress structure growth at the 8h -1 Mpc scales to which S 8 is sensitive. We expect improved constraints with upcoming high-resolution CMB and galaxy lensing and future galaxy clustering data, where we will further assess if axions can restore cosmic concordance.

Section: Jcap06(2023)023mentioning

confidence: 99%

Ultra-light axions and the S ₈ tension: joint constraints from the cosmic microwave background and galaxy clustering

Rogers

Hložek

Laguë

et al. 2023

“…Concretely, if it contributes 1% to Ω cdm the matter power spectrum will be suppressed for relevant k by ∼ 10%, more than enough to resolve the S 8 tension. While such a small fraction is not ruled out by the CMB and LSS [53], future measurements of the 21 cm signal [57] will be able to constrain small fractions of very light axion dark matter. Interestingly, in [38] a phenomenological model was studied with a period of early dark energy but supplemented by a small contribution from a separate very light scalar.…”

Section: Jcap03(2023)037 4 Discussion and Conclusionmentioning

confidence: 99%

Addressing the Hubble and S ₈ tensions with a kinetically mixed dark sector

Alexander

Bernardo

Toomey

2023

We present a kinetically mixed dark sector (KMIX) model to address the Hubble and S 8 tensions. Inspired from string theory, our model includes two fields: an axion, which plays a role similar to the scalar field in early dark energy models, and a dilaton. This theory differs from other axio-dilaton models aimed at the Hubble tension in that there is necessarily kinetic mixing between the two fields which allows for efficient energy transfer from the axion into the dilaton which has w ≈ 1. As a direct consequence of these dynamics, we find the model does not need to resort to a fine-tuned potential to solve the Hubble tension and naturally accommodates a standard axion potential. Furthermore, the axion will necessarily makeup a small (fuzzy) fraction of Ωcdm once it begins to oscillate at the bottom of its potential and will suppress the growth of perturbations on scales sensitive to S 8. Interestingly, the scale of the potential for the dilaton has to be small, ≲ 𝒪(10 meV)4, suggesting the possibility for a connection to dark energy. Implementing the dynamics for the background and perturbations in a modified Boltzmann code we calculate the CMB and matter power spectra for our theory. Exploring the parameter space of our model, we find regions which can accommodate a ∼ 10% increase in H 0 from the Planck inferred value and S 8 values that are consistent with large-scale structure constraints.

“…5 eV, CMB and LSS data impose that the ULAs relic density obeys Ω a /Ω d ≤ 0.05 and Ω a h 2 ≤ 0.006 [16,17]. In the mass window 10 −25 eV ∼ 10 −23 eV, future experiments such as HERA will be sensitive to f FDM of order 0.01 [15]. Even if ultra-light axions were to be only a fraction of the dark matter, it would still be possible for the whole dark matter to be comprised of axions spanning a much wider mass range, in an axiverse-like scenario with an extended mass function [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…Heavier masses in the FDM window have been studied through black hole superradiance [11], while Lyα constraints have been shrinking the allowed window from above [12][13][14]. However, if one allows FDM to constitute just a fraction f FDM of the totality of dark matter, the JCAP03(2024)001 allowed mass range still spans many orders of magnitude, see [15]. It is possible for FDM to exist in large portions in the region 10 −25 eV-10 −23 eV, while for lighter masses current constraints suggest f FDM ≲ 10 −2 , and for heavier masses f FDM ≲ 10 −1 .…”

Section: Introductionmentioning

confidence: 99%

Dark ages, a window on the dark sector. Hunting for ultra-light axions

Vanzan,

Raccanelli,

Bartolo

2024

Measurements of 21 cm intensity mapping (IM) during the dark ages can potentially provide us with an unprecedented window on high redshifts and small scales. One of the main advantages this can bring involves the possibility to probe the nature of dark matter. Tests of dark matter models with the large-scale structure of the Universe are limited by non-linearities and astrophysical effects, which are not present for IM measurements during the dark ages. In this paper we focus on constraining the model in which dark matter is comprised, totally or in part, by ultra-light axion-like particles around the 10-18– 10-22 eV mass scale. For this model, the angular power spectrum of 21 cm brightness temperature fluctuations will exhibit a small-scale suppression. However, this effect is intertwined with the imprint of baryon-dark matter relative velocity at recombination, causing at the same time an enhancement at large-scales, which is affected by the mass and abundance of axion dark matter. In this work we forecast how future radio arrays will be able to constrain ultra-light axion mass through both these effects on the angular power spectrum.