GMRT observation towards detecting the Post-reionization 21-cm signal

Abstract

We have analyzed 610 MHz GMRT observations towards detecting the redshifted 21-cm signal from z=1.32. The multi-frequency angular power spectrum C_l(Delta nu) is used to characterize the statistical properties of the background radiation across angular scales ~20" to 10', and a frequency bandwidth of 7.5 MHz with resolution 125 kHz. The measured C_l(Delta nu) which ranges from 7 mK^2 to 18 mK^2 is dominated by foregrounds, the expected HI signal C_l^HI(Delta nu) ~10^{-6}- 10^{-7} mK^2 is several orders of magnitude smaller. The foregrounds, believed to originate from continuum sources, is expected to vary smoothly with Delta nu whereas the HI signal decorrelates within ~0.5 MHz and this holds the promise of separating the two. For each l, we use the interval 0.5 < Delta nu < 7.5 MHz to fit a fourth order polynomial which is subtracted from the measured C_l(Delta nu) to remove any smoothly varying component across the entire bandwidth Delta nu < 7.5 MHz. The residual C_l(Delta nu), we find, has an oscillatory pattern with amplitude and period respectively ~0.1 mK^2 and Delta nu = 3 MHz at the smallest l value of 1476, and the amplitude and period decreasing with increasing l. Applying a suitably chosen high pass filter, we are able to remove the residual oscillatory pattern for l=1476 where the residual C_l(Delta nu) is now consistent with zero at the 3-sigma noise level. We conclude that we have successfully removed the foregrounds at l=1476 and the residuals are consistent with noise. We use this to place an upper limit on the HI signal whose amplitude is determined by x_HI b where x_HI and b are the HI neutral fraction and the HI bias respectively. A value of x_HI b greater than 7.95 would have been detected in our observation, and is therefore ruled out at the 3-sigma level. (abridged)

29 pages, 13 figures, Accepted to MNRAS

References in corpus (45)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization
• 21 Centimeter Fluctuations from Cosmic Gas at High Redshifts
• Damped Lyman Alpha Systems at z<1.65: The Expanded SDSS HST Sample
• Baryon Acoustic Oscillation Intensity Mapping as a Test of Dark Energy
• Foregrounds and Forecasts for the Cosmic Microwave Background
• Multifrequency analysis of 21 cm fluctuations from the Era of Reionization
• Foreground simulations for the LOFAR - Epoch of Reionization Experiment
• Discovery of Damped Lyman-Alpha Systems at Redshifts Less Than 1.65 and Results on their Incidence and Cosmological Mass Density
• Fossil HII Regions: Self-Limiting Star Formation at High Redshift
• The evolution of Omega(HI) and the epoch of formation of damped Lyman-alpha absorbers
• The CMBR fluctuations from HI perturbations prior to reionization
• Radio Foregrounds for the 21cm Tomography of the Neutral Intergalactic Medium at High Redshifts
• Evolution of Neutral Gas at High Redshift -- Implications for the Epoch of Galaxy Formation
• Foregrounds for observations of the cosmological 21 cm line: I. First Westerbork measurements of Galactic emission at 150 MHz in a low latitude field
• Foreground Contamination in Interferometric Measurements of the Redshifted 21 cm Power Spectrum
• Twenty-one centimeter tomography with foregrounds
• On using visibility correlations to probe the HI distribution from the dark ages to the present epoch I: Formalism and the expected signal
• Deep multi-frequency radio imaging in the Lockman Hole using the GMRT and VLA: I. The nature of the sub-mJy radio population
• Foregrounds for 21cm Observations of Neutral Gas at High Redshift
• An Improved Method for 21cm Foreground Removal
• Improving Foreground Subtraction in Statistical Observations of 21 cm Emission from the Epoch of Reionization
• Foregrounds for redshifted 21 cm studies of reionization: GMRT 153 MHz observations
• The multi-frequency angular power spectrum of the epoch of reionization 21 cm signal
• Using HI to probe large scale structures at z ~ 3
• The Angular Two-Point Correlation Function for the FIRST Radio Survey
• HI as a Probe of the Large Scale Structure in the Post-Reionization Universe
• HI Fluctuations at Large Redshifts: I--Visibility correlation
• Fluctuations in 21cm Emission After Reionization
• Will point sources spoil 21 cm tomography?
• The SDSS Damped Lya Survey: Data Release 1
• Maximum-likelihood estimation of the CMB power spectrum from interferometer observations
• A search for HI 21cm absorption in strong MgII absorbers in the redshift desert
• First Detection of Cosmic Structure in the 21-cm Intensity Field
• The 21cm Power Spectrum After Reionization
• A Study of ISM of Dwarf Galaxies Using HI Power Spectrum Analysis
• Cosmological constraints from 21cm surveys after reionization
• Estimation of Cosmological Parameters from HI Observations of Post-reionization Epoch
• HI Fluctuations at Large Redshifts: III - Simulating the Signal Expected at GMRT
• A 610-MHz survey of the Lockman Hole with the Giant Metrewave Radio Telescope - I. Observations, data reduction and source catalogue for the central 5 square degrees
• What will anisotropies in the clustering pattern in redshifted 21 cm maps tell us?
• HI Fluctuations at Large Redshifts: II - the Signal Expected for GMRT
• Neutral hydrogen at high redshifts as a probe of structure formation - III. Radio maps from N-Body simulations
• Using Gravitational Lensing to study HI clouds at high redshift
• HI as a Probe of the Large Scale Structure in the Post-Reionization Universe: Visibility Correlations and Prospects for Detection

Cited by in corpus (45)

• Characterizing Foreground for redshifted 21-cm radiation: 150 MHz GMRT observations
• Modeling the neutral hydrogen distribution in the post-reionization Universe: intensity mapping
• Improved foreground removal in GMRT 610 MHz observations towards redshifted 21-cm tomography
• SKAO HI Intensity Mapping: Blind Foreground Subtraction Challenge
• Visibility based angular power spectrum estimation in low frequency radio interferometric observations
• Modelling the post-reionization neutral Hydrogen (\HI) bias
• 21 cm observation of LSS at z~1 Instrument sensitivity and foreground subtraction
• The visibility based Tapered Gridded Estimator (TGE) for the redshifted 21-cm power spectrum
• Constraining large scale HI bias using redshifted 21-cm signal from the post-reionization epoch
• Prospects of observing a quasar HII region during the Epoch of Reionization with redshifted 21cm
• Tapering the sky response for angular power spectrum estimation from low-frequency radio-interferometric data
• Demonstrating the Tapered Gridded Estimator (TGE) for the Cosmological HI 21-cm Power Spectrum using $150\mathrm{MHz}$ GMRT observations
• Prospects for detecting the 326.5 MHz redshifted 21 cm HI signal with the Ooty Radio Telescope (ORT)
• The angular power spectrum measurement of the Galactic synchrotron emission in two fields of the TGSS survey
• A Tapered Gridded Estimator (TGE) for the Multi-Frequency Angular Power Spectrum (MAPS) and the Cosmological HI 21-cm Power Spectrum
• Structure Formation and the Global 21-cm Signal in the Presence of Coulomb-like Dark Matter-Baryon Interactions
• First multi-redshift limits on post-Epoch of Reionization (post-EoR) 21 cm signal from z = 1.96 - 3.58 using uGMRT
• All sky angular power spectrum: I. Estimating brightness temperature fluctuations using TGSS 150 MHz survey
• On using large scale correlation of the Ly-$\alpha$ forest and redshifted 21-cm signal to probe HI distribution during the post reionization era
• A Technique for Foreground Subtraction in Redshifted 21 cm Observations
• A Bayesian analysis of redshifted 21-cm HI signal and foregrounds: Simulations for LOFAR
• Characterizing EoR foregrounds: A study of the Lockman Hole Region at 325 MHz
• Redshift space distortions of the {\rm HI} 21-cm intensity mapping signal due to the internal motions within galaxies
• Fisher matrix predictions for detecting the cosmological 21 cm signal with the Ooty Wide Field Array (OWFA)
• Towards 21-cm Intensity Mapping at $z=2.28$ with uGMRT using the Tapered Gridded Estimator I: Foreground Avoidance
• Constraining dark energy using the cross correlations of weak lensing with post-reionization probes of neutral hydrogen
• Simulated foreground predictions for HI at z = 3.35 with the Ooty Wide Field Array: I. Instrument and the foregrounds
• The Tracking Tapered Gridded Estimator for the 21-cm power spectrum from MWA drift scan observations I: Validation and preliminary results
• Towards $21$-cm intensity mapping at $z=2.28$ with uGMRT using the tapered gridded estimator III: Foreground removal
• An analytical method to simulate the HI 21-cm visibility signal for intensity mapping experiments
• An Image-based Tapered Gridded Estimator (ITGE) for the angular power spectrum
• Towards $21$-cm intensity mapping at $z=2.28$ with uGMRT using the tapered gridded estimator -- IV. Wideband analysis
• Towards $21$-cm intensity mapping at $z=2.28$ with uGMRT using the tapered gridded estimator II: Cross-polarization power spectrum
• Simulating the z = 3.35 HI 21-cm visibility signal for the Ooty Wide Field Array(OWFA)
• A Method to Extract the Angular Power Spectrum of the Epoch of Reionization from Low-Frequency Radio Interferometers
• The Tracking Tapered Gridded Estimator (TTGE) for the power spectrum from drift scan observations
• Simulated Predictions for HI at $z=3.35$ with the Ooty Wide Field Array (OWFA) -- II: Foreground Avoidance
• Probing the Epoch of Reionization using synergies of line intensity mapping
• Influence of synchrotron self-absorption on the 21cm experiments
• Estimating statistics of sky brightness using radio interferometric observations
• Synthetic Observations with the Square Kilometre Array (SKA) -- development towards an end-to-end pipeline
• Signatures of Synchrotron Radiation from the Annihilation of Dark Matter at the Galactic Centre
• The prospects of measuring the angular power spectrum of the diffuse Galactic synchrotron emission with SKA1 Low
• A semi-cosmographic approach to study cosmological evolution in phase space
• Probing dark energy using anisotropies in the clustering of post-EoR HI distribution