On the detection of spectral ripples from the Recombination Epoch

Abstract

Photons emitted during the epochs of Hydrogen ($500\lesssim z\lesssim 1600$) and Helium recombination ($1600\lesssim z\lesssim 3500$ for HeII $\to$ HeI, $5000\lesssim z\lesssim 8000$ for HeIII $\to$ HeII) are predicted to appear as broad, weak spectral distortions of the Cosmic Microwave Background. We present a feasibility study for a ground-based experimental detection of these recombination lines, which would provide an observational constraint on the thermal ionization history of the Universe, uniquely probing astrophysical cosmology beyond the last scattering surface. We find that an octave band in the 2--6 GHz window is optimal for such an experiment, both maximizing signal-to-noise ratio and including sufficient line spectral structure. At these frequencies the predicted signal appears as an additive quasi-sinusoidal component with amplitude about $8$ nK that is embedded in a sky spectrum some nine orders of magnitude brighter. We discuss an algorithm to detect these tiny spectral fluctuations in the sky spectrum by foreground modeling. We introduce a \textit{Maximally Smooth} function capable of describing the foreground spectrum and distinguishing the signal of interest. With Bayesian statistical tests and mock data we estimate that a detection of the predicted distortions is possible with 90\% confidence by observing for 255 days with an array of 128 radiometers using cryogenically cooled state-of-the-art receivers. We conclude that detection is in principle feasible in realistic observing times; we propose APSERa---Array of Precision Spectrometers for the Epoch of Recombination---a dedicated radio telescope to detect these recombination lines.

33 pages, 16 figures, submitted to ApJ, comments welcome

References in corpus (17)

• PRISM (Polarized Radiation Imaging and Spectroscopy Mission): An Extended White Paper
• A refined model for spinning dust radiation
• Distinguishing different scenarios of early energy release with spectral distortions of the cosmic microwave background
• Lines in the cosmic microwave background spectrum from the epoch of cosmological helium recombination
• Foreground Model and Antenna Calibration Errors in the Measurement of the Sky-Averaged λ21 cm Signal at z~20
• Primordial helium recombination I: feedback, line transfer, and continuum opacity
• Cosmological hydrogen recombination: populations of the high level sub-states
• Free-bound emission from cosmological hydrogen recombination
• Two-photon transitions in hydrogen and cosmological recombination
• Two-photon transitions in primordial hydrogen recombination
• Unavoidable CMB spectral features and blackbody photosphere of our Universe
• Is there an unaccounted excess Extragalactic Cosmic Radio Background?
• The effect of forbidden transitions on cosmological hydrogen and helium recombination
• Two-Photon 2s<->1s Transitions during Recombination of Hydrogen in the Universe
• Rapid HeII->HeI recombination and radiation concerned with this process
• Cosmological hydrogen recombination: Lyn line feedback and continuum escape
• Is there a need and another way to measure the Cosmic Microwave Background temperature more accurately?

Cited by in corpus (34)

• Testing for calibration systematics in the EDGES low-band data using Bayesian model selection
• Rethinking CMB foregrounds: systematic extension of foreground parameterizations
• The redshifted 21-cm signal in the EDGES low-band spectrum
• Which spectral distortions does $\Lambda$CDM actually predict?
• First results on the Epoch of Reionization from First Light with SARAS 2
• SARAS 2: A Spectral Radiometer for probing Cosmic Dawn and the Epoch of Reionization through detection of the global 21 cm signal
• The synergy between CMB spectral distortions and anisotropies
• Prospects for Measuring Cosmic Microwave Background Spectral Distortions in the Presence of Foregrounds
• maxsmooth: Rapid Maximally Smooth Function Fitting With Applications in Global 21-cm Cosmology
• CosmoSpec: Fast and detailed computation of the cosmological recombination radiation from hydrogen and helium
• Results from EDGES High-Band: II. Constraints on Parameters of Early Galaxies
• GMOSS: All-sky model of spectral radio brightness based on physical components and associated radiative processes
• Modeling the Radio Foreground for detection of CMB spectral distortions from Cosmic Dawn and Epoch of Reionization
• Informing antenna design for sky-averaged 21-cm experiments using a simulated Bayesian data analysis pipeline
• Use of Time Dependent Data in Bayesian Global 21cm Foreground and Signal Modelling
• Using the cosmological recombination radiation to probe early dark energy and fundamental constant variations
• PRATUSH experiment concept and design overview
• Dust moments: towards a new modelling of the galactic dust emission for CMB B-modes analysis
• A Bayesian approach to modelling spectrometer data chromaticity corrected using beam factors -- I. Mathematical formalism
• Sensitivity forecasts for the cosmological recombination radiation in the presence of foregrounds
• Quest for CMB spectral distortions to probe the scalar-induced gravitational wave background interpretation of pulsar timing array data
• SARAS CD/EoR Radiometer: Design and performance of the Digital Correlation Spectrometer
• Using the Long Wavelength Array to Search for Cosmic Dawn
• FSD: Frequency Space Differential measurement of CMB spectral distortions
• New Horizons in Cosmology with Spectral Distortions of the Cosmic Microwave Background
• A Resistive Wideband Space Beam Splitter
• Cosmology with Recombination Spectrum
• Improvements to the Search for Cosmic Dawn Using the Long Wavelength Array
• Synthetic Observations with the Square Kilometre Array (SKA) -- development towards an end-to-end pipeline
• EDGES of the dark forest: A new absorption window into the composite dark matter and large scale structure
• Exploring Machine Learning Regression Models for Advancing Foreground Mitigation and Global 21cm Signal Parameter Extraction
• Beamforming approaches toward detecting the 21-cm global signal from Cosmic Dawn with radio array telescopes
• An SBC-based controller and processor for the laboratory model of PRATUSH Digital Receiver
• A Comprehensive Bayesian re-analysis of the SARAS2 data from the Epoch of Reionization