Azam Hussain | Searcharxiv

arXiv2018

Interacting Quintessence and Growth of Structure

In standard cosmologies, dark energy interacts only gravitationally with dark matter. An extension to this picture is interacting quintessence (IQ) model, where scalar field coupled directly to cold dark matter. The percentage deviation is studied in IQ model wrt $Λ$CDM for varied values of interacting parameter W. We investigated the effect of interaction on matter, Kaiser and galaxy power spectrums. Deviation in power spectrum increases with interaction on both large and small scales. On small scale, variation is comparatively smaller than on large scale. On large scale, it is due to dark energy perturbation while it is background evolution that causes a difference on small scale. These variations decrease with increase in redshift. Herein thawing class of model with linear potential is studied.

astro-ph.CO↗

arXiv2016

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

We investigate the prospect of constraining scalar field dark energy models using HI 21-cm intensity mapping surveys. We consider a wide class of coupled scalar field dark energy models whose predictions about the background cosmological evolution are different from the $Λ$CDM predictions by a few percent. We find that these models can be statistically distinguished from $Λ$CDM through their imprint on the 21-cm angular power spectrum. At the fiducial $z= 1.5$, corresponding to a radio interferometric observation of the post-reionization HI 21 cm observation at frequency $568 \rm MHz$, these models can infact be distinguished from the $Λ$CDM model at $ {\rm SNR }> 3 σ$ level using a 10,000 hr radio observation distributed over 40 pointings of a SKA1-mid like radio-telescope. We also show that tracker models are more likely to be ruled out in comparison with $Λ$CDM than the thawer models. Future radio observations can be instrumental in obtaining tighter constraints on the parameter space of dark energy models and supplement the bounds obtained from background studies.

astro-ph.CO↗