The impact of non-Planckian effects on cosmological radio backgrounds

Abstract

Non-Planckian (NP) spectral modifications of the CMB radiation spectrum can be produced due to the existence of a non-zero value of the plasma frequency at the recombination epoch. We present here an analysis of NP effects on the radio cosmological background and we derive, for the first time, predictions of their amplitude on three different observables: the CMB spectrum, the Sunyaev-Zel'dovich (SZ) effect in cosmic structures, and the 21-cm background temperature brightness change. We find that NP effect can manifest in the CMB spectrum at $ν\simlt 400$ MHz as a drastic cut-off in the CMB intensity. Using the available CMB data in the relevant $\nu$ range (i.e., mainly at $\simlt 1$ GHz and in the COBE-FIRAS data frequency range), we derive upper limits on the plasma frequency ${\nu }_p$ = 206, 346 and 418 MHz at 1, 2 and 3 $\sigma$ confidence level, respectively. We find that the difference between the pure Planck spectrum and the one modified by NP effects is of the order of mJy/arcmin${}^2$ at $ν\simlt 0.5$ GHz and it becomes smaller at higher frequencies where it is $\sim 0.1$ mJy/arcmin${}^2$ at $ν\simgt 150$ GHz, thus indicating that the experimental route to probe NP effects in the early universe is to observe the radio cosmological background at very low frequencies.(abridged)

arXiv comment15 pages, 7 figures, accepted for publication in JCAP

References in corpus (21)

• The Cosmic Microwave Background Spectrum from the Full COBE/FIRAS Data Set
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The Sunyaev-Zel'dovich Effect
• A Textbook Example of a Bow Shock in the Merging Galaxy Cluster 1E0657-56
• A model of diffuse Galactic Radio Emission from 10 MHz to 100 GHz
• Particle decays during the cosmic dark ages
• The evolution of CMB spectral distortions in the early Universe
• Detecting Dark Matter Annihilation with CMB Polarization : Signatures and Experimental Prospects
• CMB constraints on Dark Matter models with large annihilation cross-section
• New Limits on 21cm EoR From PAPER-32 Consistent with an X-Ray Heated IGM at z=7.7
• Spectral Index of the Diffuse Radio Background Measured From 100 to 200 MHz
• The Epoch of Reionization
• Constraints on leptonically annihilating Dark Matter from reionization and extragalactic gamma background
• The Non-Thermal Sunyaev-Zel'dovich Effect in Clusters of Galaxies
• Unveiling the nature of dark matter with high redshift 21 cm line experiments
• The nature of dark matter from the global high redshift HI 21 cm signal
• Thermodynamics of photons in relativistic $e^{+}{e}^{-}\gamma$ plasmas
• A numerical code for the solution of the Kompaneets equation in cosmological context
• Perturbed Recombination from Dark Matter Annihilation
• Modifications to the Cosmic 21-cm Background Frequency Spectrum by Scattering via electrons in Galaxy Clusters
• Probing photon decay with the Sunyaev-Zel'dovich effect

Cited by in corpus (4)

• Radiation in equilibrium with plasma and plasma effects on cosmic microwave background
• Polarization of the Sunyaev-Zel'dovich effect: relativistic imprint of thermal and non-thermal plasma
• Probing the physics and history of cosmic reionization with the Sunyaev-Zel'dovich Effect
• Statistical theory of photon gas in plasma