TELAMON and OVRO detection of an inverted spectrum and radio flare of TXS0310+022 coincident with IceCube-220304A
ATel #15266; Matthias Kadler (JMU Wuerzburg), Talvikki Hovatta (Finnish Centre for Astronomy with ESO), Sebastian Kiehlmann (IoA FORTH), Anthony C. Readhead (OVRO, Caltech), Florian Eppel (JMU Wuerzburg), Jonas Hessdoerfer (JMU Wuerzburg), Florian Roesch (JMU Wuerzburg) for the TELAMON and OVRO monitoring teams
on 9 Mar 2022; 09:43 UT
Credential Certification: Matthias Kadler (matthias.kadler@astro.uni-wuerzburg.de)
Subjects: Radio, Millimeter, Gamma Ray, Neutrinos, Request for Observations, AGN, Blazar
Referred to by ATel #: 15268
We report on contemporary radio observations of TXS0310+022, a radio-loud AGN possibly associated with the recently detected high-energy neutrino IceCube-220304A (GCN#31679) and the flaring gamma-ray source 4FGL J0313.0+0229 (GCN#31701).
We observed TXS 0310+022 on Mar 6, 2022, with the Effelsberg 100-m telescope as part of the TELAMON program in the 20mm (14.25/16.75 GHz), 14mm (19.25/21.15/22.85/24.75 GHz), and 7mm (36.25/38.75 GHz) bands. We find the source to currently show a strongly inverted spectrum with flux densities of 231mJy, 268mJy, and 308mJy in the 20mm, 14mm, and 7mm bands, respectively.
The OVRO monitoring program has observed TXS 0310+022 at 15GHz between December 2020 and November 2021. The lowest flux densities were measured on a level of about 200-250mJy in early and late 2021. Starting in June 2021, the 15GHz flux density was rising and peaked near mid September 2021, at about 330mJy before it dropped again to about 220mJy in November 2021.
Together, the TELAMON and OVRO data show that the source TXS 0310+022 was strongly variable in the months preceding the neutrino event reaching flux-density maxima substantially higher than historically recorded values (e.g., as listed in the RFC catalog). At the time of the neutrino event, the source was found with an unusual inverted spectrum indicative of high-frequency activity.
The TELAMON program (Kadler et al. 2021, Proc. ICRC 2021) is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics. The OVRO 40m Telescope at California Institute of Technology is used to regularly monitor a large number of AGN at 15 GHz . It is currently supported by private funding from the California Insitute of Technology and the Max Planck Institute for Radio Astronomy.
