Millimeter to ????-Ray Variability of AGN found in the SPTpol 500 degree2 field

• Main Authors: John Hood, South Pole Telescope Collaboration
• Format: Conference Object
• Language: English
• Published: 2022
• Subjects: Active Galactic Nuclei; South Pole Telescope; correlated variability; South Pole; South pole
• Online Access: https://zenodo.org/record/5961836; https://doi.org/10.5281/zenodo.5961836

Abstract: Cosmic Microwave Background (CMB) telescopes are now providing an option for daily monitoring of these objects within limited fields of view. While continuous, high-cadence monitoring of active galactic nuclei (AGN) is now common at gamma-ray, optical, and radio frequencies, AGN monitoring in the millimeter (mm) band has mostly been restricted to short campaigns on targeted sources. Here we use the South Pole Telescope (SPT), which was designed to observe the CMB at arcminute and larger angular scales, to monitor AGN. Between 2013 and 2016, the SPTpol instrument (the second-generation mm-wave camera mounted on the SPT) was used to continuously scan a 500 deg2 field, covering the entire field several times per day with detectors sensitive to polarization and radiation in bands centered at 95 and 150 GHz. This data set enables the monitoring of tens of mm-bright AGN on timescales from years to days at high signal to noise (S/N > 10 in a 36-hour coadd). We use SPTpol 150 GHz observations to monitor the variability of the sources in the mm-waveband and directly compare that to other frequencies. In a pilot study, we focus on the source PKS 2326-502, which has extensive, day-timescale monitoring data in gamma-ray, optical, and now mm-wave data between 2013 and 2016. We present a search for evidence of correlated variability between SPTpol (150 GHz), SMARTS (O/IR) and Fermi (gamma-rays) observations. This pilot study is paving the way for AGN monitoring with current and upcoming CMB experiments like SPT-3G, SO and CMB-S4, including multi-wavelength variability studies with upcoming facilities such as VRO-LSST.