A study on the Clustering Properties of Radio-Selected sources in the Lockman Hole Region at 325 MHz

TL;DR

This study investigates the clustering properties of radio-selected extragalactic sources at 325 MHz in the Lockman Hole, providing the first such analysis at this frequency and offering insights into the distribution of dark matter and galaxy evolution.

Contribution

It presents the first measurement of clustering and bias parameters of radio sources at 325 MHz, classifies sources into AGNs and SFGs, and compares their clustering properties.

Findings

AGNs have higher spatial correlation length and bias than SFGs.

Clustering properties at 325 MHz are intermediate between high and low-frequency studies.

The study highlights the importance of multi-frequency observations to understand cosmic variance.

Abstract

Studying the spatial distribution of extragalactic source populations is vital in understanding the matter distribution in the Universe. It also enables understanding the cosmological evolution of dark matter density fields and the relationship between dark matter and luminous matter. Clustering studies are also required for EoR foreground studies since it affects the relevant angular scales. This paper investigates the angular and spatial clustering properties and the bias parameter of radio-selected sources in the Lockman Hole field at 325 MHz. The data probes sources with fluxes $\gtrsim$0.3 mJy within a radius of 1.8$^\circ$ around the phase center of a $6^\circ \times 6^\circ$ mosaic. Based on their radio luminosity, the sources are classified into Active Galactic Nuclei (AGNs) and Star-Forming Galaxies (SFGs). Clustering and bias parameters are determined for the combined populations and the classified sources. The spatial correlation length and the bias of AGNs are greater than SFGs -- indicating that more massive haloes host the former. This study is the first reported estimate of the clustering property of sources at 325 MHz, intermediate between the preexisting studies at high and low-frequency bands. It also probes a well-studied deep field at an unexplored frequency with moderate depth and area. Clustering studies require such observations along different lines of sight, with various fields and data sets across frequencies to avoid cosmic variance and systematics. Thus, an extragalactic deep field has been studied in this work to contribute to this knowledge.