Wandering in the Lyman-alpha Forest: A Study of Dark Matter-Dark Radiation Interactions

Abstract

The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provides no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of $2\Delta \ln \mathcal{L}=12$ with respect to the standard $\Lambda$ cold dark matter ($\Lambda$CDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to $2\Delta \ln \mathcal{L}=6$ relative to $\Lambda$CDM. We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, $\Delta N_{\mathrm{fluid}}$, will be improved by an order of magnitude compared to current bounds.

11 pages + references, 3 figures, 3 tables, v2: added references,v3: published version

References in corpus (16)

• The Clustering of the SDSS DR7 Main Galaxy Sample I: A 4 per cent Distance Measure at z=0.15
• A Theory of Dark Matter
• New Constraints on the free-streaming of warm dark matter from intermediate and small scale Lyman-$\alpha$ forest data
• The Cosmic Linear Anisotropy Solving System (CLASS) I: Overview
• Dark Matter and Dark Radiation
• Is dark matter with long-range interactions a solution to all small-scale problems of ΛCDM cosmology?
• Lensing is Low: Cosmology, Galaxy Formation, or New Physics?
• Resonant Dark Forces and Small Scale Structure
• Cosmology with self-interacting sterile neutrinos and dark matter - A pseudoscalar model
• Using BBN in cosmological parameter extraction from CMB: a forecast for Planck
• Light dark photon and fermionic dark radiation for the Hubble constant and the structure formation
• $\nu \Lambda$MDM: A Model for Sterile Neutrino and Dark Matter Reconciles Cosmological and Neutrino Oscillation Data after BICEP2
• Cosmological Constraints on Interacting Light Particles
• Residual Non-Abelian Dark Matter and Dark Radiation
• Dark Radiation Alleviates Problems with Dark Matter Halos
• Hidden Charged Dark Matter and Chiral Dark Radiation

Cited by in corpus (22)

• In the Realm of the Hubble tension $-$ a Review of Solutions
• Challenges for $\Lambda$CDM: An update
• CMB-S4 Science Case, Reference Design, and Project Plan
• The implications of an extended dark energy cosmology with massive neutrinos for cosmological tensions
• Interacting Dark Sector and Precision Cosmology
• The Weak Gravity Conjecture and Emergence from an Ultraviolet Cutoff
• Constraining Dark Matter -- Dark Radiation interactions with CMB, BAO, and Lyman-$\alpha$
• Probing the Small-Scale Matter Power Spectrum with Large-Scale 21-cm Data
• An emulator for the Lyman-$\alpha$ forest in beyond-$\Lambda$CDM cosmologies
• Gravitational Lensing and the Power Spectrum of Dark Matter Substructure: Insights from the ETHOS N-body Simulations
• Lyman-$\alpha$ forest constraints on interacting dark sectors
• Constraints on dark matter-neutrino scattering from the Milky-Way satellites and subhalo modeling for dark acoustic oscillations
• Inflationary Features and Shifts in Cosmological Parameters from Planck 2015 Data
• Probing neutrino interactions and dark radiation with gravitational waves
• Astrophysical Tests of Dark Matter Self-Interactions
• Two sides of the same coin: sterile neutrinos and dark radiation. Status and perspectives
• Addressing Astrophysical and Cosmological Problems With Secretly Asymmetric Dark Matter
• Searching for Signatures of Dark matter-Dark Radiation Interaction in Observations of Large-scale Structure
• Self-interacting neutrinos, the Hubble parameter tension, and the Cosmic Microwave Background
• Probing Dark Relativistic Species and Their Interactions with Dark Matter through CMB and 21cm surveys
• Science from an Ultra-Deep, High-Resolution Millimeter-Wave Survey
• Equality scale-based and sound horizon-based analysis of the Hubble tension