Tapomoy Guha Sarkar

Cross-correlation of the H i 21-cm signal and Lyα forest: a probe of cosmology

Separating the cosmological redshifted 21-cm signal from foregrounds is a major challenge. We present the cross-correlation of the redshifted 21-cm emission from neutral hydrogen (H i) in the post-reionization era with the Lyα forest as a new probe of the large-scale matter distribution in the redshift range z = 2-3 without the problem of foreground contamination. Though the 21-cm and the Lyα forest signals originate from different astrophysical systems, they are both expected to trace the underlying dark matter distribution on large scales. The multifrequency angular cross-correlation power spectrum estimator is found to be unaffected by the discrete quasar sampling, which only affects the noise in the estimate. We consider a hypothetical redshifted 21-cm observation in a single field of view 1°.3 (FWHM) centred at z = 2.2, where the binned 21-cm angular power spectrum can be measured at a signal-to-noise ratio (S/N) of 3σ or better across the range 500 ≤ l ≤ 4000. Keeping the parameters of the 21-cm observation fixed, we have estimated the S/N for the cross-correlation signal varying the quasar angular number density n of the Lyα forest survey. Assuming that the spectra have S/N ~ 5 in pixels of length 44 km s -1 , we find that a 5σ detection of the cross-correlation signal is possible at 600 ≤ l ≤ 2000 with n = 4 deg -2 . This value of n is well within the reach of upcoming Lyα forest surveys. The cross-correlation signal will be a new, independent probe of the astrophysics of the diffuse intergalactic medium (IGM), the growth of structure and the expansion history of the Universe.

On using large scale correlation of the Ly-α forest and redshifted 21-cm signal to probe HI distribution during the post reionization era

We investigate the possibility of detecting the 3D cross correlation power spectrum of the Ly-

Primordial non-Gaussianity in the forest: 3D bispectrum of Lyman-α flux spectra along multiple lines of sight.

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The CMBR ISW and HI 21 cm cross-correlation angular power spectrum

forest and HI 21 cm signal from the post reionization epoch. The cross-correlation signal is directly dependent on the dark matter power spectrum and is sensitive to the 21-cm brightness temperature and Ly-

Predictions for BAO distance estimates from the cross-correlation of the Lyman-α forest and redshifted 21-cm emission

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Probing primordial non-Gaussianity: the 3D Bispectrum of Ly-α forest and the redshifted 21-cm signal from the post reionization epoch

forest biases. These bias parameters dictate the strength of anisotropy in redshift space. We find that the cross-correlation power spectrum can be detected using

Prospects of probing quintessence with HI 21-cm intensity mapping survey

400 ~ \, \rm hrs

Constraining neutrino mass using the large-scale H i distribution in the post-reionization epoch

observation with SKA-mid (phase 1) and a futuristic BOSS like experiment with a quasar (QSO) density of

Thermal properties of a particle confined to a parabolic quantum well in two-dimensional space with conical disclination.

30 ~ \rm deg^{-2}

CMBR weak lensing and HI 21-cm cross-correlation angular power spectrum

at a peak SNR of