相关论文: Simulating the z = 3.35 HI 21-cm visibility signal…

We have used the Fisher matrix formalism to quantify the prospects of detecting the z = 3.35 redshifted 21-cm HI power spectrum with the upcoming radio-imterferometric array OWFA. OWFA's frequency and baseline coverage spans comoving…

Foreground removal is the most important step in detecting the large-scale redshifted HI 21-cm signal. Modelling foreground spectra is challenging and is further complicated by the chromatic response of the telescope. We present a…

We use the Fisher matrix formalism to predict the prospects of measuring the redshifted 21-cm power spectrum in different $k$-bins using observations with the upcoming Ooty Wide Field Array (OWFA) which will operate at $326.5 {\rm MHZ}$.…

Distribution of cold gas in the post-reionization era provides an important link between distribution of galaxies and the process of star formation. Redshifted 21 cm radiation from the Hyperfine transition of neutral Hydrogen allows us to…

Considering the upcoming OWFA, we use simulations of the foregrounds and the $z = 3.35$ HI 21-cm intensity mapping signal to identify the $(k_{\perp},k_{\parallel})$ modes where the expected 21-cm power spectrum $P(k_{\perp},k_{\parallel})$…

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…

Simulations play a vital role in testing and validating HI 21-cm power spectrum estimation techniques. Conventional methods use techniques like N-body simulations to simulate the sky signal which is then passed through a model of the…

One of the scientific objectives of the Ooty Wide Field Array(OWFA) is to observe the redshifted HI emission from z ~ 3.35. Although predictions spell out optimistic outcomes in reasonable integration times, these studies were based purely…

We have studied the possibility of measuring the cross-correlation of the redshifted HI 21-cm signal and the Lyman-$\alpha$ forest using an upcoming radio-interferometric array OWFA and an spectroscopic observation like SDSS-IV. Our results…

Observations of the redshifted 21 cm HI fluctuations promise to be an important probe of the post-reionization era. In this paper we calculate the expected signal and foregrounds for the upgraded Ooty Radio Telescope (ORT) which operates at…

The legacy Ooty Radio Telescope (ORT) is being reconfigured as a 264-element synthesis telescope, called the Ooty Wide Field Array (OWFA). Its antenna elements are the contiguous 1.92 m sections of the parabolic cylinder. It will operate in…

We describe here an ongoing upgrade to the legacy Ooty Radio Telescope (ORT).The ORT is a cylindrical parabolic cylinder 530mx30m in size operating at a frequency of 326.5 (or z ~ 3.35 for the HI 21cm line). The telescope has been…

We developed a generic formalism to estimate the event rate and the redshift distribution of Fast Radio Bursts (FRBs) in our previous publication (Bera et al. 2016), considering FRBs are of an extragalactic origin. In this paper we present…

In this paper, we review the results of interplanetary scintillation (IPS) observations made with the legacy system of the Ooty Radio Telescope (ORT) and compare them with the possibilities opened by the upgraded ORT, the Ooty Wide Field…

Upcoming galaxy surveys with the SKA Observatory will detect neutral hydrogen (HI) across unprecedented volumes, and their scientific return will crucially depend on predictive models for HI observables. In this work, we present a framework…

Redshifted 21 cm radiation originating from the cosmological distribution of neutral hydrogen (HI) appears as a background radiation in low frequency radio observations. The angular and frequency domain fluctuations in this radiation carry…

Radio-frequency interference (RFI) is a major systematic limitation in radio astronomy, particularly for science cases requiring high sensitivity, such as 21 cm cosmology. Traditionally, RFI is dealt with by identifying its signature in the…

We use a large N-body simulation to examine the detectability of HI in emission at redshift z ~ 1, and the constraints imposed by current observations on the neutral hydrogen mass function of galaxies at this epoch. We consider three…

Observations of fluctuations in the redshifted 21 cm radiation from neautral hydrogen (HI) are perceived to be an important future probe of the universe at high redshifts. Under the assumption that at redshifts z less than 6…

Observations of the EoR with the 21-cm hyperfine emission of neutral hydrogen (HI) promise to open an entirely new window onto the formation of the first stars, galaxies and accreting black holes. In order to characterize the weak 21-cm…