Searching for blue in the dark
Reviewed by Pith T0 review T1 audit T2 compute T3 formal T4 kernel pith:UOTPHL4Rrecord.jsonopen to challenge →
read the original abstract
The primordial power spectrum of curvature perturbations has been well-measured on large scales but remains fairly unconstrained at smaller scales, where significant deviations from $\Lambda$CDM may occur. Measurements of 21-cm intensity mapping in the dark ages promise to access very small scales that have yet to be probed, extending beyond the reach of cosmic microwave background and galaxy surveys. In this paper, we investigate how small-scale power-law enhancements -- or blue tilts -- of the primordial power spectrum affect the 21-cm power spectrum. We consider generic enhancements due to curvature modes, isocurvature modes, and runnings of the spectral tilt. We present forecasts for Earth- and lunar-based instruments to detect a blue-tilted primordial spectrum. We find that an Earth-based instrument capable of reaching the dark ages could detect any enhancements of power on nearly all the scales it can observe, which depends on the baseline of the interferometer. The smallest scales observed by such an instrument can only detect a very strong enhancement. However, an instrument on the far side of the Moon of the same size would be able to probe shallower slopes with higher precision. We forecast results for instruments with $100 \, {\rm km} \, (3000 \, {\rm km})$ baselines and find that they can probe up to scales of order $k_{\rm max} \sim 8 \, {\rm Mpc}^{-1} \, (k_{\rm max} \sim 250 \, {\rm Mpc}^{-1})$, thereby providing invaluable information on exotic physics and testing inflationary models on scales not otherwise accessible.
This paper has not been read by Pith yet.
Forward citations
Cited by 6 Pith papers
-
Isocurvature Induced Gravitational Waves at Pulsar Timing Arrays
The work shows that free-streaming dark radiation isocurvature produces a qualitatively different gravitational wave spectrum than cold dark matter isocurvature and derives constraints on isocurvature power spectra ar...
-
Growth of Structure in Multi-species Wave Dark Matter
Derives the power spectrum evolution and cross-spectra for arbitrary multi-species wave and particle dark matter, incorporating free-streaming, Jeans scales, and intrinsic fluctuations.
-
Multi-species Dark Matter with Warmth and Randomness
Presents a general analytic framework based on truncated BBGKY hierarchy solved via Volterra equations for computing power spectra in multi-species dark matter with finite velocity dispersion and Poisson fluctuations.
-
Quantum production of gravitational waves after inflation
Scalar metric perturbations after inflation break conformal invariance and induce quantum production of gravitons, generating a GW spectrum that peaks near GHz frequencies for standard primordial scalar power spectra.
-
New Isocurvature Constraints from JWST UV Luminosity Function
First UVLF-based constraints on model-agnostic isocurvature power spectra for CDM, baryon, neutrino, and dark radiation modes yield consistent 95% credible envelopes over k ~ 0.5-10 Mpc^{-1}.
-
Early Growth of Structure in Warm Wave Dark Matter
Derives suppression of adiabatic perturbations and scale-dependent growth of isocurvature power in warm wave dark matter, verifies with Schrödinger-Poisson simulations, and proposes an analytic halo mass function.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.