311 citations · 2.2k across the 66 of their papers we have counts for
59 papers
Constraining the neutral hydrogen (HI) distribution
Minal Chhabra, Raghunath Ghara, Somnath Bharadwaj
We constrain the HI distribution by jointly modeling two independent, existing observations of the 21-cm signal, the HI density parameter measured using…
Fuzzy Dark Matter Halo Mass Functions at Cosmic Dawn
Raghunath Ghara, Adam Lidz, Daniel Grin +1
In fuzzy dark matter (FDM) cosmological models, wave effects impact astrophysical length scales, suppressing the abundance of small mass dark matter halos, and delaying the earlies…
POLAR-II: modeling star formation history of galaxies on the 21-cm signal from Epoch of Reionization
Qing-Bo Ma, Raghunath Ghara, Benedetta Ciardi +6
Galaxies may suffer some starburst and quenched periods in their history due to e.g. galaxy mergers and feedback. However, semi-numerical simulations of the Epoch of Reionization (…
Enhancing the detectability of ionized Regions during the Epoch of Reionization
Rutvik Ashish Mahajan, Raghunath Ghara, Nishant Pradeep Deo +1
We present an improved matched filter method for detecting large ionized regions in 21 cm observations of the Epoch of Reionization. In addition to detection, the method constrains…
Improved upper limits on the 21-cm signal power spectrum at and from an optimal field observed with NenuFAR
S. Munshi, F. G. Mertens, J. K. Chege +19
We report the deepest upper limits to date on the power spectrum of the 21-cm signal during the Cosmic Dawn (redshifts: ), using four nights of observations with NenuFAR. The…
The Effect of Large Optical Depths on the Non-Gaussian 21-cm signal from Cosmic Dawn
Iffat Nasreen, Kanan K. Datta, Abinash K. Shaw +6
During the Cosmic Dawn (CD), the HI 21-cm optical depth ( ) in the intergalactic medium can become significantly large. Consequently, the second and higher-order terms of ap…
Constraints on the state of the IGM at using redshifted 21-cm observations with LOFAR
R. Ghara, S. Zaroubi, B. Ciardi +21
The power spectra of the redshifted 21-cm signal from the Epoch of Reionization (EoR) contain information about the ionization and thermal states of the intergalactic medium (IGM),…
First upper limits on the 21-cm signal power spectrum of neutral hydrogen at from the LOFAR 3C196 field
E. Ceccotti, A. R. Offringa, F. G. Mertens +16
The redshifted 21-cm signal of neutral hydrogen from the Epoch of Reionization (EoR) can potentially be detected using low-frequency radio instruments such as the Low-Frequency Arr…
Deeper multi-redshift upper limits on the Epoch of Reionization 21-cm signal power spectrum from LOFAR between z=8.3 and z=10.1
F. G. Mertens, M. Mevius, L. V. E. Koopmans +20
We present new upper limits on the 21-cm signal power spectrum from the Epoch of Reionization (EoR), at redshifts , based on reprocessed obse…
Near-field imaging of local interference in radio interferometric data: Impact on the redshifted 21 cm power spectrum
S. Munshi, F. G. Mertens, L. V. E. Koopmans +24
Radio-frequency interference (RFI) is a major systematic limitation in radio astronomy, particularly for science cases requiring high sensitivity, such as 21 cm cosmology. Traditio…
Spectral modelling of Cygnus A between 110 and 250 MHz. Impact on the LOFAR 21-cm signal power spectrum
E. Ceccotti, A. R. Offringa, L. V. E. Koopmans +15
Studying the redshifted 21-cm signal from the the neutral hydrogen during the Epoch of Reionization and Cosmic Dawn is fundamental for understanding the physics of the early univer…
Extracting the Epoch of Reionization Signal with 3D U-Net Neural Networks Using Data-driven Systematic Effect Model
Li-Yang Gao, Léon V. E. Koopmans, Florent G. Mertens +11
Neutral hydrogen (HI) serves as a crucial probe for the Cosmic Dawn and the Epoch of Reionization (EoR). Actual observations of the 21-cm signal often encounter challenges such as…
Exploring the effect of different cosmologies on the Epoch of Reionization 21-cm signal with POLAR
Anshuman Acharya, Qing-bo Ma, Sambit K. Giri +8
A detection of the 21-cm signal power spectrum from the Epoch of Reionization is imminent, thanks to consistent advancements from telescopes such as LOFAR, MWA, and HERA, along wit…
Asking Fast Radio Bursts for More than Reionization History
Abinash Kumar Shaw, Raghunath Ghara, Paz Beniamini +2
We propose different estimators to probe the intergalactic medium (IGM) during epoch of reionization (EoR) using the dispersion measure () of the fast radio bursts. We co…
Revised LOFAR upper limits on the 21-cm signal power spectrum at using Machine Learning and Gaussian Process Regression
Anshuman Acharya, Florent Mertens, Benedetta Ciardi +3
The use of Gaussian Process Regression (GPR) for foregrounds mitigation in data collected by the LOw-Frequency ARray (LOFAR) to measure the high-redshift 21-cm signal power spectru…
Inferring IGM parameters from the redshifted 21-cm Power Spectrum using Artificial Neural Networks
Madhurima Choudhury, Raghunath Ghara, Saleem Zaroubi +8
The high redshift 21-cm signal promises to be a crucial probe of the state of the intergalactic medium (IGM). Understanding the connection between the observed 21-cm power spectrum…
Impact of the Epoch of Reionization sources on the 21-cm bispectrum
Leon Noble, Mohd Kamran, Suman Majumdar +5
The morphology of the 21-cm signal emitted by the neutral hydrogen present in the intergalactic medium (IGM) during the Epoch of Reionization (EoR) depends both on the properties o…
Probing the intergalactic medium during the Epoch of Reionization using 21-cm signal power spectra
Raghunath Ghara, Abinash Kumar Shaw, Saleem Zaroubi +9
The redshifted 21-cm signal from the epoch of reionization (EoR) directly probes the ionization and thermal states of the intergalactic medium during that period. In particular, th…
21-cm Signal from the Epoch of Reionization: A Machine Learning upgrade to Foreground Removal with Gaussian Process Regression
Anshuman Acharya, Florent Mertens, Benedetta Ciardi +7
In recent years, a Gaussian Process Regression (GPR) based framework has been developed for foreground mitigation from data collected by the LOw-Frequency ARray (LOFAR), to measure…
First upper limits on the 21 cm signal power spectrum from cosmic dawn from one night of observations with NenuFAR
S. Munshi, F. G. Mertens, L. V. E. Koopmans +24
The redshifted 21 cm signal from neutral hydrogen is a direct probe of the physics of the early universe and has been an important science driver of many present and upcoming radio…
The morphology of the redshifted 21-cm signal from the Cosmic Dawn
Raghunath Ghara, Satadru Bag, Saleem Zaroubi +1
The spatial fluctuations in the tomographic maps of the redshifted 21-cm signal from the Cosmic Dawn (CD) crucially depend on the size and distribution of the regions with gas temp…
POLAR -- I: linking the 21-cm signal from the epoch of reionization to galaxy formation
Qing-Bo Ma, Raghunath Ghara, Benedetta Ciardi +5
To self-consistently model galactic properties, reionization of the intergalactic medium, and the associated 21-cm signal, we have developed the algorithm polar by integrating the…
Studying the Multi-frequency Angular Power Spectrum of the Cosmic Dawn 21-cm Signal
Abinash Kumar Shaw, Raghunath Ghara, Saleem Zaroubi +5
The light-cone (LC) anisotropy arises due to cosmic evolution of the cosmic dawn 21-cm signal along the line-of-sight (LoS) axis of the observation volume. The LC effect makes the…
Probing early universe through redshifted 21-cm signal: Modelling and observational challenges
Abinash Kumar Shaw, Arnab Chakraborty, Mohd Kamran +8
The redshifted 21-cm radiation from the atomic hydrogen (HI) provides an excellent direct probe to study the evolution of HI in IGM and thus reveal the nature of the first luminous…