We investigate the prospects of detecting the cross correlation of CMBR weak-lensing convergence field with the large scale tracers of the underlying dark matter distribution in the post-reionization epoch. The cross-correlation is then used to make error projections for dark energy equation of state (EoS)for models with a time evolving dark energy. We study the cross-correlation angular power spectrum of the weak-lensing field with the Lyman-α forest and the redshifted HI 21 cm signal from the post reionization epoch. The angular power spectra is expressed as a line of sight average over the tomographic slices. We find that on using multiple 400 hrs observation with an extended uGMRT like instrument or with a BOSS like survey with quasar (QSO) density of 16 deg−2 the cross-correlation with weak-lensing convergence field covering half the sky can be detected at a very high SNR (> 20). The cross-correlation of weak-lensing with Lyman-α forest allows the 1−σ errors on the dark energy EoS parameters for different parametrizations to be constrained at a level of precision comparable to combined Planck+SNIa+BAO+HST projections. The 21-cm weak-lensing cross-correlation is found to provide strong constraints on the present value of the dark energy EoS parameter at 4% for the 7CPL model. The constraints on wa is comparable (~12%) for models other than the 7CPL model. We also find that the CPL parametrization may not be the best constrained parametrization for dark energy evolution. The cross-correlation of CMBR weak-lensing with the post-reionization probes of neutral hydrogen thus holds the potential to give us valuable understanding about the nature of evolving dark energy.

No abstract

In this work we investigate the possibility of constraining a thawing Quintessence scalar field model for dark energy. We propose using the imprint of baryon acoustic oscillation (BAO) on the cross-correlation of post-reionization 21-cm signal and galaxy weak lensing convergence field to tomographically measure the angular diameter distance DA(z) and the Hubble parameter H(z). The projected errors in these quantities are then used to constrain the Quintessence model parameters. We find that independent 600hrs radio interferometric observation at four observing frequencies 916MHz, 650 MHz, 520 MHz and 430MHz with a SKA-1-Mid like radio telescope in cross-correlation with a deep weak lensing survey covering half the sky may measure the binned DA and H at a few percent level of sensitivity. The Monte Carlo analysis for a power law thawing Quientessence model gives the 1 − σ marginalized bounds on the initial slope λi, dark energy density parameter Ωφ0 and the shape of the potential Γ at $8.63\%$, $10.08\%$ and $9.75\%$ respectively. The constraints improve to $7.66\%$, $4.39\%$ and $5.86\%$ respectively when a joint analysis with SN and other probes is performed.

We propose the intensity mapping of the redshifted H i 21-cm signal from the post-reionization epoch as a cosmological probe of f (R) gravity. We consider the Hu-Sawicki family of f (R) gravity models characterized by a single parameter f,R0. The f (R) modification to gravity affects the postreionization 21-cm power spectrum through the change in the growth rate of density fluctuations. The quantity of interest is the redshift space distortion parameter βT (k, z) which imprints the change. We find that a radio interferometric observation at an observing frequency 710MHz with a SKA-1-Mid like radio telescope may measure the binned βT (k) at a level of sensitivity to distinguish f (R) models with log 10 |f,R0| > −5 at a > 5 − σ level in the k range k > 0.4M P c −1 . We find that using a Fisher matrix analysis the 68% bound obtained on the parameter is −5.62 < log 10 |f,R0| < −4.38 which is competitive with other probes of f (R) gravity. Thus the future observation of the post-reionization H i signal holds the potential to put robust constraints on f (R) gravity models and enrich our understanding of late time cosmic evolution and structure formation.

In this work we investigate the possibility of constraining a thawing Quintessence scalar field model for dark energy. We propose using the imprint of baryon acoustic oscillation (BAO) on the cross-correlation of post-reionization 21-cm signal and galaxy weak lensing convergence field to tomographically measure the angular diameter distance D A (z) and the Hubble parameter H(z). The projected errors in these quantities are then used to constrain the Quintessence model parameters. We find that independent 600hrs radio interferometric observation at four observing frequencies 916MHz, 650 MHz, 520 MHz and 430MHz with a SKA-1-Mid like radio telescope in cross-correlation with a deep weak lensing survey covering half the sky may measure the binned D A and H at a few percent level of sensitivity. The Monte Carlo analysis for a power law thawing Quientessence model gives the 1 − σ marginalized bounds on the initial slope λ i , dark energy density parameter Ω φ0 and the shape of the potential Γ at 8.63%, 10.08% and 9.75% respectively. The constraints improve to 7.66%, 4.39% and 5.86% respectively when a joint analysis with SN and other probes is performed.