Z. Chen, S. Cunnington, A. Pourtsidou, L. Wolz, M. Spinelli, J. L. Bernal, M. Barberi-Squarotti, S. Camera, I. P. Carucci, J. Fonseca, K. Grainge, M. O. Irfan, M. G. Santos, J. Wang, Meerklass Collaboration
Abstract
We present a novel analysis of observational systematics through the emission-line stacking of the MeerKLASS L-band deep-field intensity maps, following the detection in MeerKLASS Collaboration et al. A stacking signal is obtained by stacking the 21 cm intensity map cubelets around the galaxy positions from the GAMA survey at 0.39 ≲ z ≲ 0.46. An extensive simulation framework is built to study the viability of the stacking detection, the covariance estimation, and the model inference, which are then applied to the data. The statistical significance of the detection is 8.66σ when averaged into an angular map, and 7.45σ when averaged into a spectrum. The stacked spectrum exhibits an oscillating component of systematics, and we provide evidence that these systematics are a convolutional effect on the map data. The oscillation frequency matches the diffraction from the secondary reflector into the primary beam of the MeerKAT telescope. Bayesian inference can be used to constrain the systematics and the average H I emission of the galaxies. The fitting of the parameters gives a constraint on the systematics frequency νsys[MHz]=17.90‑4.27+6.53 . The posterior of the systematics amplitude reaches the wide prior and gives Asys=0.50‑0.33+0.33 . A tentative measurement of the average H I mass of the sources is achieved at log10[
Keywords
Observational cosmology / Radio astronomy / H I line emission / 1146 / 1338 / 690 / Cosmology and Nongalactic Astrophysics / Astrophysics of Galaxies
The Astrophysical Journal Supplement Series
Volume 279, Number 279, Page 30
2025 June
