activity
20152023
most citedImproved upper limits on the 21-cm signal power spectrum of neutral hydrogen at from LOFAR

311 citations · 516 across the 7 of their papers we have counts for

collaborators

8 papers

eess.SP2023

Run-Time Monitors Design for Adaptive Radar Systems: A Practical Framework

Pepijn Cox, Mario Coutino, Giuseppe Papari +2

Adaptivity in multi-function radar systems is rapidly increasing, especially when moving towards fully adaptive, cognitive radar systems. However, the large number of available sys…

astro-ph.CO2020★ 43 cited

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…

astro-ph.CO2020★ 311 cited

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…

astro-ph.IM2018★ 40 cited

Quantifying Suppression of the Cosmological 21-cm Signal due to Direction Dependent Gain Calibration in Radio Interferometers

A. Mouri Sardarabadi, L. V. E. Koopmans

The 21-cm signal of neutral hydrogen - emitted during the Epoch of Reionization - promises to be an important source of information for the study of the infant universe. However, i…

astro-ph.IM2018★ 111 cited

The first power spectrum limit on the 21-cm signal of neutral hydrogen during the Cosmic Dawn at z=20-25 from LOFAR

B. K. Gehlot, F. G. Mertens, L. V. E. Koopmans +19

Observations of the redshifted 21-cm hyperfine line of neutral hydrogen from early phases of the Universe such as Cosmic Dawn and the Epoch of Reionization promise to open a new wi…

stat.CO2018

Constrained Least Squares for Extended Complex Factor Analysis

Ahmad Mouri Sardarabadi, Alle-Jan van der Veen, L. V. E. Koopmans

For subspace estimation with an unknown colored noise, Factor Analysis (FA) is a good candidate for replacing the popular eigenvalue decomposition (EVD). Finding the unknowns in fa…

astro-ph.IM2018

Efficient Calibration of Radio Interferometers Using Block LDU Decomposition

Ahmad Mouri Sardarabadi, Alle-Jan van der Veen, Léon V. E. Koopmans

Having an accurate calibration method is crucial for any scientific research done by a radio telescope. The next generation radio telescopes such as the Square Kilometre Array (SKA…

astro-ph.IM2015★ 11 cited

Radio Astronomical Image Formation using Constrained Least Squares and Krylov Subspaces

Ahmad Mouri Sardarabadi, Amir Leshem, Alle-Jan van der Veen

Image formation for radio astronomy can be defined as estimating the spatial power distribution of celestial sources over the sky, given an array of antennas. One of the challenges…