A Comprehensive Bayesian re-analysis of the SARAS2 data from the Epoch of Reionization

Abstract

We present a Bayesian re-analysis of the sky-averaged 21-cm experimental data from SARAS2 using nested sampling implemented with polychord, spectrally smooth foreground modelling implemented with maxsmooth, detailed systematic modelling and rapid signal emulation with globalemu. Our analysis differs from previous analysis of the SARAS2 data through the use of a full Bayesian framework and separate modelling of the foreground and non-smooth systematics. We use the most up-to-date signal models including Lyman-$\alpha$ and CMB heating parameterised by astrophysical parameters such as star formation efficiency, X-ray heating efficiency, minimal virial circular velocity of star forming galaxies, CMB optical depth and the low energy cutoff of the X-ray spectral energy distribution. We consider models with an excess radio background above the CMB produced via radio emission from early galaxies and parameterised by a radio production efficiency. A non-smooth systematic is identified and modelled as both a frequency damped sinusoid introduced by the electronics and separately from the sky. The latter is modulated by the total efficiency of the antenna and marginally favoured by the data. We consider three different models for the noise in the data. The SARAS2 constraints on individual astrophysical parameters are extremely weak however we identify classes of disfavoured signals. We weakly disfavour standard astrophysical models with high Lyman-$\alpha$ fluxes and weak heating and more confidently disfavour exotic models with high Lyman-$\alpha$ fluxes, low X-ray efficiencies and high radio production efficiencies in early galaxies.

arXiv comment19 Pages, 13 Figures. Accepted by MNRAS

References in corpus (77)

• emcee: The MCMC Hammer
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• An absorption profile centred at 78 megahertz in the sky-averaged spectrum
• 21-cm cosmology
• 21-cm Tomography of the Intergalactic Medium at High Redshift
• Possible interaction between baryons and dark-matter particles revealed by the first stars
• PolyChord: nested sampling for cosmology
• PolyChord: next-generation nested sampling
• ARCADE 2 Measurement of the Extra-Galactic Sky Temperature at 3-90 GHz
• Insights on Dark Matter from Hydrogen during Cosmic Dawn
• The Spin-Kinetic Temperature Coupling and the Heating Rate due to Lyman Alpha Scattering before Reionization: Predictions for 21cm Emission and Absorption
• Enhanced global signal of neutral hydrogen due to excess radiation at cosmic dawn
• Severely Constraining Dark Matter Interpretations of the 21-cm Anomaly
• Concerns about Modelling of the EDGES Data
• Signs of Dark Matter at 21-cm?
• Modeling the Radio Background from the First Black Holes at Cosmic Dawn: Implications for the 21 cm Absorption Amplitude
• Early-Universe Constraints on Dark Matter-Baryon Scattering and their Implications for a Global 21cm Signal
• The observable signature of late heating of the Universe during cosmic reionization
• Charting the Parameter Space of the Global 21-cm Signal
• Signature of Excess Radio Background in the 21-cm Global Signal and Power Spectrum
• Foregrounds for observations of the cosmological 21 cm line: I. First Westerbork measurements of Galactic emission at 150 MHz in a low latitude field
• What does the first highly-redshifted 21-cm detection tell us about early galaxies?
• Design and characterization of the Large-Aperture Experiment to Detect the Dark Age (LEDA) radiometer systems
• The signature of the first stars in atomic hydrogen at redshift 20
• Constraining Baryon--Dark Matter Scattering with the Cosmic Dawn 21-cm Signal
• Tighter Limits on Dark Matter Explanations of the Anomalous EDGES 21cm Signal
• HERA Phase I Limits on the Cosmic 21-cm Signal: Constraints on Astrophysics and Cosmology During the Epoch of Reionization
• Reviving Millicharged Dark Matter for 21-cm Cosmology
• Testing for calibration systematics in the EDGES low-band data using Bayesian model selection
• A Ground Plane Artifact that Induces an Absorption Profile in Averaged Spectra from Global 21-cm Measurements - with Possible Application to EDGES
• The Radio Background Below 100 MHz
• The redshifted 21-cm signal in the EDGES low-band spectrum
• First results on the Epoch of Reionization from First Light with SARAS 2
• The Rise of the First Stars: Supersonic Streaming, Radiative Feedback, and 21-cm Cosmology
• Results from EDGES High-Band: I. Constraints on Phenomenological Models for the Global $21$ cm Signal
• Constraining the intergalactic medium at $z\approx$ 9.1 using LOFAR Epoch of Reionization observations
• SARAS 2 constraints on global 21-cm signals from the Epoch of Reionization
• The simulated 21 cm signal during the epoch of reionization : full modeling of the Ly-alpha pumping
• Decoding the X-ray Properties of Pre-Reionization Era Sources
• anesthetic: nested sampling visualisation
• SARAS 2: A Spectral Radiometer for probing Cosmic Dawn and the Epoch of Reionization through detection of the global 21 cm signal
• The Scattering of Lyman-series Photons in the Intergalactic Medium
• Lyman-alpha radiative transfer during the Epoch of Reionization: contribution to 21-cm signal fluctuations
• Tight Constraints on the Excess Radio Background at $z=9.1$ from LOFAR
• High-redshift radio galaxies: a potential new source of 21-cm fluctuations
• Interpreting LOFAR 21-cm signal upper limits at z~9.1 in the context of high-z galaxy and reionisation observations
• Heating of the intergalactic medium by the cosmic microwave background during cosmic dawn
• Quantifying dimensionality: Bayesian cosmological model complexities
• The subtlety of Ly-a photons: changing the expected range of the 21-cm signal
• The rich complexity of 21-cm fluctuations produced by the first stars
• A General Bayesian Framework for Foreground Modelling and Chromaticity Correction for Global 21cm Experiments
• Emulating the Global 21-cm Signal from Cosmic Dawn and Reionization
• fgivenx: A Python package for functional posterior plotting
• Exploring reionisation and high-z galaxy observables with recent multi-redshift MWA upper limits on the 21-cm signal
• Results from EDGES High-Band: III. New Constraints on Parameters of the Early Universe
• Is there an unaccounted excess Extragalactic Cosmic Radio Background?
• Constraining the state of the intergalactic medium during the Epoch of Reionization using MWA 21-cm signal observations
• On the detection of spectral ripples from the Recombination Epoch
• maxsmooth: Rapid Maximally Smooth Function Fitting With Applications in Global 21-cm Cosmology
• Heating and cooling of the intergalactic medium by resonance photons
• SARAS 3 CD/EoR Radiometer: Design and Performance of the Receiver
• GLOBALEMU: A novel and robust approach for emulating the sky-averaged 21-cm signal from the cosmic dawn and epoch of reionisation
• Lyman-$\alpha$ coupling and heating at Cosmic Dawn
• Radio background and IGM heating due to Pop III supernovae explosions
• Quantifying Ionospheric Effects on Global 21-cm Observations
• Results from EDGES High-Band: II. Constraints on Parameters of Early Galaxies
• On the contamination of the global 21~cm signal from polarized foregrounds
• 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
• Detecting Early Galaxies Through Their 21-cm Signature
• Simulations of Galactic polarized synchrotron emission for Epoch of Reionization observations
• CosmoReionMC: A package for estimating cosmological and astrophysical parameters using CMB, Lyman-α absorption and global 21 cm data
• ARTIST: Fast radiative transfer for large-scale simulations of the epoch of reionisation
• The Impact of Neutral Intergalactic Gas on Lyman-$\alpha$ Intensity Mapping During Reionization
• An updated estimate of the cosmic radio background and implications for ultra-high-energy photon propagation
• SARAS CD/EoR Radiometer: Design and performance of the Digital Correlation Spectrometer
• Maximum amplitude of the high-redshift 21-cm absorption feature

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• The Second Radio Synchrotron Background Workshop: Conference Summary and Report
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