VLA/JVLA Monitoring of Bright Northern Radio Sources

TL;DR

This study uses multi-epoch VLA/JVLA observations to validate Planck flux densities, extend radio SEDs, and analyze variability of bright northern radio sources across multiple frequencies.

Contribution

It provides the first comprehensive validation of Planck flux scales and extends radio SEDs to lower frequencies for bright sources.

Findings

JVLA and Planck flux densities agree within 3% at 30 and 44 GHz.

Median variability is 2% over two months and 14% over one year.

On 1-6 year timescales, median variability is approximately 16%.

Abstract

We report multiple epoch VLA/JVLA observations of 89 northern hemisphere sources, most with 37\,GHz flux density > 1 Jy, observed at 4.8, 8.5, 33.5, and 43.3 GHz. The high frequency selection leads to a predominantly flat spectrum sample, with 85% of our sources being in the Planck Early Release Compact Source Catalog (ERCSC). These observations allow us to: 1) validate Planck's 30 and 44 GHz flux density scale, 2) extend the radio SEDs of Planck sources to lower frequencies allowing for the full 5-857GHz regime to be studied, and 3) characterize the variability of these sources. At 30 GHz and 44 GHz, the JVLA and Planck flux densities agree to within 3%. On timescales of less than two months the median variability of our sources is 2%. On timescales of about a year the median variability increases to 14%. Using the WMAP 7-year data, the 30 GHz median variability on a 1-6 years timescale is 16%.