598 citations · 2.3k across the 38 of their papers we have counts for
38 papers
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…
Transient RFI environment of LOFAR-LBA at 72-75 MHz: Impact on ultra-widefield AARTFAAC Cosmic Explorer observations of the redshifted 21-cm signal
B. K. Gehlot, L. V. E. Koopmans, S. A. Brackenhoff +13
Measurement of the redshifted 21-cm signal of neutral hydrogen from the Cosmic Dawn (CD) and Epoch of Reionisation (EoR) promises to unveil a wealth of information about the astrop…
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…
A novel radio imaging method for physical spectral index modelling
E. Ceccotti, A. R. Offringa, L. V. E. Koopmans +9
We present a new method, called "forced-spectrum fitting", for physically-based spectral modelling of radio sources during deconvolution. This improves upon current common deconvol…
Retrieving the 21-cm signal from the Epoch of Reionization with learnt Gaussian process kernels
Florent G. Mertens, Jérôme Bobin, Isabella P. Carucci
Direct detection of the Cosmic Dawn and Epoch of Reionization via the redshifted 21-cm line of neutral Hydrogen will have unprecedented implications for studying structure formatio…
Deep learning approach for identification of HII regions during reionization in 21-cm observations -- II. foreground contamination
Michele Bianco, Sambit. K. Giri, David Prelogović +5
The upcoming Square Kilometre Array Observatory (SKAO) will produce images of neutral hydrogen distribution during the epoch of reionization by observing the corresponding 21-cm si…
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…
Accurate modelling of the Lyman- coupling for the 21-cm signal, observability with NenuFAR and SKA
Benoit Semelin, Romain Mériot, Florent Mertens +6
The measurement of the cm signal from the Cosmic Dawn is a major goal for several existing and upcoming radio interferometers such as NenuFAR and the SKA. During this era befo…
Assessing the impact of two independent direction-dependent calibration algorithms on the LOFAR 21-cm signal power spectrum
H. Gan, F. G. Mertens, L. V. E. Koopmans +11
Detecting the 21-cm signal from the Epoch of Reionisation (EoR) is challenging due to the strong astrophysical foregrounds, ionospheric effects, radio frequency interference and in…
Statistical analysis of the causes of excess variance in the 21 cm signal power spectra obtained with the Low-Frequency Array
H. Gan, L. V. E Koopmans, F. G. Mertens +11
The detection of the 21 cm signal of neutral hydrogen from the Epoch of Reionization (EoR) is challenging due to bright foreground sources, radio frequency interference (RFI), the…
Degree-Scale Galactic Radio Emission at 122 MHz around the North Celestial Pole with LOFAR-AARTFAAC
B. K. Gehlot, L. V. E. Koopmans, A. R. Offringa +11
Aims: Contamination from bright diffuse Galactic thermal and non-thermal radio emission poses crucial challenges in experiments aiming to measure the 21-cm signal of neutral hydrog…
A numerical study of 21-cm signal suppression and noise increase in direction-dependent calibration of LOFAR data
M. Mevius, F. Mertens, L. V. E. Koopmans +14
We investigate systematic effects in direction dependent gain calibration in the context of the Low-Frequency Array (LOFAR) 21-cm Epoch of Reionization (EoR) experiment. The LOFAR…
SKA-Low Intensity Mapping Pathfinder Updates: Deeper 21 cm Power Spectrum Limits from Improved Analysis Frameworks
Nichole Barry, Gianni Bernardi, Bradley Greig +2
The Square Kilometre Array (SKA) is a planned radio interferometer of unprecedented scale that will revolutionize low-frequency radio astronomy when completed. In particular, one o…
Exploring the Cosmic Dawn with NenuFAR
F. G. Mertens, B. Semelin, L. V. E. Koopmans
The exploration of the Cosmic Dawn, the period of the Universe during which the first stars and galaxies were formed, is one of the last frontiers of modern astronomy and cosmology…
A detailed kinematic study of 3C 84 and its connection to Gamma-rays
Jeffrey A. Hodgson, Bindu Rani, Junghwan Oh +7
3C 84 (NGC 1275) is the bright radio core of the Perseus Cluster. Even in the absence of strong relativistic effects, the source has been detected at Gamma-rays up to TeV energies.…
21cm signal predictions at Cosmic Dawn and Reionization with coupled radiative-hydrodynamics
Nicolas J. F. Gillet, Dominique Aubert, Florent G. Mertens +1
The process of heating and reionization of the Universe at high redshift links small scale structures/galaxy formation and large scale inter-galactic medium properties. Even if the…
Comparing Foreground Removal Techniques for Recovery of the LOFAR-EoR 21cm Power Spectrum
Ian Hothi, Emma Chapman, Jonathan R. Pritchard +10
We compare various foreground removal techniques that are being utilised to remove bright foregrounds in various experiments aiming to detect the redshifted 21cm signal of neutral…
The AARTFAAC Cosmic Explorer: observations of the 21-cm power spectrum in the EDGES absorption trough
B. K. Gehlot, F. G. Mertens, L. V. E. Koopmans +12
The 21-cm absorption feature reported by the EDGES collaboration is several times stronger than that predicted by traditional astrophysical models. If genuine, a deeper absorption…
Interpreting LOFAR 21-cm signal upper limits at z~9.1 in the context of high-z galaxy and reionisation observations
Bradley Greig, Andrei Mesinger, Léon V. E. Koopmans +11
Using the latest upper limits on the 21-cm power spectrum at from the Low Frequency Array (LOFAR), we explore regions of parameter space which are inconsistent with t…
Foreground modelling via Gaussian process regression: an application to HERA data
Abhik Ghosh, Florent Mertens, Gianni Bernardi +70
The key challenge in the observation of the redshifted 21-cm signal from cosmic reionization is its separation from the much brighter foreground emission. Such separation relies on…
Tight Constraints on the Excess Radio Background at from LOFAR
R. Mondal, A. Fialkov, C. Fling +13
The ARCADE2 and LWA1 experiments have claimed an excess over the Cosmic Microwave Background (CMB) at low radio frequencies. If the cosmological high-redshift contribution to this…
Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at from LOFAR
F. G. Mertens, M. Mevius, L. V. E Koopmans +23
A new upper limit on the 21-cm signal power spectrum at a redshift of is presented, based on 141 hours of data obtained with the Low-Frequency Array (LOFAR). The an…
Constraining the intergalactic medium at 9.1 using LOFAR Epoch of Reionization observations
R. Ghara, S. K. Giri, G. Mellema +19
We derive constraints on the thermal and ionization states of the intergalactic medium (IGM) at redshift 9.1 using new upper limits on the 21-cm power spectrum measured b…
Precision requirements for interferometric gridding in 21-cm power spectrum analysis
A. R. Offringa, F. Mertens, S. van der Tol +4
We analyse the accuracy of radio interferometric gridding of visibilities with the aim to quantify the Epoch of Reionization (EoR) 21-cm power spectrum bias caused by gridding, ult…