14 papers
Mitigating incoherent excess variance in high-redshift 21 cm observations with multi-output cross-Gaussian process regression
S. Munshi, L. V. E. Koopmans, F. G. Mertens +8
Systematic effects that limit the achievable sensitivity of current low-frequency radio telescopes to the 21 cm signal are among the foremost challenges in observational 21 cm cosm…
The impact of lunar topography on the 21-cm power spectrum for grid-based arrays : Insights for the Dark-ages EXplorer (DEX)
S. Ghosh, L. V. E. Koopmans, C. Brinkerink +17
The Dark Ages (DA) provides a crucial window into the physics of the infant Universe, with the 21-cm signal offering the only direct probe for mapping out the three-dimensional dis…
The impact of diffuse Galactic emission on direction-independent gain calibration in high-redshift 21 cm observations
C. Höfer, L. V. E. Koopmans, S. A. Brackenhoff +7
This study examines the impact of diffuse Galactic emission (DGE) on sky-based direction-independent (DI) gain calibration using realistic forward simulations of Low-Frequency Arra…
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…
Robust direction-dependent gain-calibration of beam-modelling errors far from the target field
S. A. Brackenhoff, A. R. Offringa, M. Mevius +8
Many astronomical questions require deep, wide-field observations at low radio frequencies. Phased arrays like LOFAR and SKA-low are designed for this, but have inherently unstable…
A circularly polarized low-frequency radio burst from the exoplanetary system HD 189733
X. Zhang, P. Zarka, J. N. Girard +17
We aim to detect low-frequency radio emission from exoplanetary systems, which can provide insights into planetary magnetic fields, star-planet interactions, stellar activity, and…