A Comprehensive Catalog of Radio Sources and Rotation Measures in the Perseus Molecular Cloud from Very Large Array Observations

TL;DR

This study provides an extensive catalog of radio sources and their rotation measures in the Perseus molecular cloud, significantly improving the mapping of magnetic fields through advanced radio polarization observations with the VLA.

Contribution

It presents the first large-scale, high-sensitivity polarization survey of the Perseus cloud, increasing the density of rotation measure samples by over an order of magnitude and revealing detailed magnetic field structures.

Findings

Detected 1410 radio sources with spectral indices indicating non-thermal emission.

Measured 205 polarized sources with high significance, greatly enhancing magnetic field mapping.

Revealed coherent large-scale and small-scale magnetic field structures across the cloud.

Abstract

We present a comprehensive radio polarization study of the Perseus molecular cloud using wideband L-band observations from the Karl G. Jansky Very Large Array. Our survey covers $\sim13.8$~deg$^2$ with a mean Stokes~$I$ sensitivity of $\sim80~\mu$Jy~beam$^{-1}$, enabling the detection of 1410 compact radio sources. From this population, we construct a catalog of source properties, including positions, integrated flux densities, and spectral indices measured across nine spectral windows. The majority of sources exhibit negative spectral indices, consistent with non-thermal synchrotron emission. Using RM Synthesis and RM CLEAN techniques, we detect 205 polarized background sources above an $8\sigma$ threshold. This corresponds to a sampling density of $\sim14.8$~deg$^{-2}$, representing more than an order-of-magnitude increase compared to previous NVSS-based measurements. The resulting rotation measures exhibit coherent large-scale variations across the surveyed region, with additional small-scale structure superimposed. The enhanced sensitivity, frequency coverage, and sampling density of our observations enable a substantially improved mapping of the line-of-sight magnetic field component toward the Perseus molecular cloud compared to previous surveys.