A Spherical Harmonic Analysis of the Ooty Wide Field Array (OWFA) Visibility Signal

Abstract

Considering redshifted $21$-cm intensity mapping with the upcoming OWFA whose field of view subtends $\sim 57^{\circ }$ in the N-S direction, we present a formalism which relates the measured visibilities to the spherical harmonic coefficients of the sky signal. We use this to calculate window functions which relate the two-visibility correlations {\it i.e.} the correlation between the visibilities measured at two baselines and two frequencies, to different multipoles of the multi-frequency angular power spectrum $C_{\ell }({\nu }_1,{\nu }_2)$. The formalism here is validated using simulations. We also present approximate closed form analytical expressions which can be used to calculate the window functions. Comparing the widely adopted flat sky approximation, we find that its predictions match those of our spherical harmonic formalism to within $16\%$ across the entire OWFA baseline range. The match improves at large baselines where we have $<5\%$ deviations.

arXiv commentSubmitted to MNRAS

References in corpus (32)

• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• Baryon Acoustic Oscillation Intensity Mapping as a Test of Dark Energy
• Late-time cosmology with 21cm intensity mapping experiments
• PAPER-64 Constraints on Reionization: The 21cm Power Spectrum at z=8.4
• Toward Epoch of Reionization Measurements with Wide-Field Radio Observations
• All-Sky Interferometry with Spherical Harmonic Transit Telescopes
• Coaxing Cosmic 21cm Fluctuations from the Polarized Sky using m-mode Analysis
• On using visibility correlations to probe the HI distribution from the dark ages to the present epoch I: Formalism and the expected signal
• Baryonic Acoustic Oscillations in 21cm Emission: A Probe of Dark Energy out to High Redshifts
• The Tianlai project: a 21cm cosmology experiment
• The multi-frequency angular power spectrum of the epoch of reionization 21 cm signal
• Using HI to probe large scale structures at z ~ 3
• A ground-based 21cm Baryon acoustic oscillation survey
• HI Fluctuations at Large Redshifts: I--Visibility correlation
• MITEoR: A Scalable Interferometer for Precision 21 cm Cosmology
• Spherical Harmonic Analyses of Intensity Mapping Power Spectra
• Estimation of Cosmological Parameters from HI Observations of Post-reionization Epoch
• Cosmological constraints from 21cm surveys after reionization
• Sky reconstruction from transit visibilities: PAON-4 and Tianlai Dish Array
• Near term measurements with 21 cm intensity mapping: neutral hydrogen fraction and BAO at z<2
• 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
• The Ooty Wide Field Array
• Prospects for detecting the 326.5 MHz redshifted 21 cm HI signal with the Ooty Radio Telescope (ORT)
• Deconvolving the Wedge: Maximum-Likelihood Power Spectra via Spherical-Wave Visibility Modeling
• Sky reconstruction for the Tianlai cylinder array
• Primordial Non-Gaussianity in the Forest: 3D Bispectrum of Ly-alpha Flux Spectra Along Multiple Lines of Sight
• Fisher matrix predictions for detecting the cosmological 21 cm signal with the Ooty Wide Field Array (OWFA)
• Simulated foreground predictions for HI at z = 3.35 with the Ooty Wide Field Array: I. Instrument and the foregrounds
• The Receiver System for the Ooty Wide Field Array
• An analytical method to simulate the HI 21-cm visibility signal for intensity mapping experiments
• Simulating the z = 3.35 HI 21-cm visibility signal for the Ooty Wide Field Array(OWFA)

Cited by in corpus (4)

• The Tianlai Dish Pathfinder Array: design, operation and performance of a prototype transit radio interferometer
• The Tianlai Cylinder Pathfinder Array: System Functions and Basic Performance Analysis
• Simulated Predictions for HI at $z=3.35$ with the Ooty Wide Field Array (OWFA) -- II: Foreground Avoidance
• Constraining warm dark matter power spectrum using the cross-correlation of HI 21 cm signal and the Lyman-$\alpha$ forest