A Comprehensive VLA Catalog of Radio Sources and Faraday Rotation Measures Toward the Perseus Molecular Cloud

We present a new high-sensitivity catalog of radio sources and rotation measures (RMs) toward the Perseus Molecular Cloud, derived from broadband L-band observations conducted with the Karl G. Jansky Very Large Array (VLA). The primary objective of this study is to probe the three-dimensional magnetic field structure in this nearby star-forming region by analyzing the linearly polarized synchrotron emission from background extragalactic radio sources. The observations span nine spectral windows between 1 and 2 GHz and achieve a sensitivity of ∼80 μJy/beam, representing an order-of-magnitude improvement over the NRAO VLA Sky Survey (NVSS). This enhanced sensitivity enabled the detection of over 1200 radio sources, of which 188 exhibit significant linear polarization and yield robust RMs (≥8σ), derived using RM synthesis and RM CLEAN.

Source extraction and spectral index fitting were performed using PyBDSF, revealing a population dominated by negative spectral indices, consistent with synchrotron emission. These RM measurements allow us to constrain the line-of-sight magnetic field component (B_los) across Perseus with unprecedented spatial resolution.

Our catalog significantly improves RM coverage in the Perseus region compared to earlier NVSS-based studies, which were limited by sparse source density and large RM uncertainties due to restricted bandwidth. In future work, this dataset, when combined with Planck dust polarization maps tracing the plane-of-sky magnetic field component (B_pos), will provide the foundation for a full three-dimensional reconstruction of the magnetic field morphology within the cloud. These results highlight the power of deep, wideband radio polarization surveys to probe magnetized structures in star-forming regions and establish a basis for comparison with MHD simulations and dust-based diagnostics of magnetic field evolution.