The radio blazar TXS 1749-101 coincident with two high-energy neutrinos: IceCube alerts 181023A and the recent 220425A
ATel #15363; A. V. Plavin (ASC Lebedev, MIPT), Y. Y. Kovalev (ASC Lebedev, MIPT, MPIfR), S. V. Troitsky (INR), Yu. A. Kovalev (ASC Lebedev), A. V. Popkov (MIPT, ASC Lebedev), A. K. Erkenov (SAO RAS), Y. V. Sotnikova (SAO RAS) on behalf of the RATAN-600 monitoring team, Florian Eppel (JMU Wuerzburg), Andrea Gokus (JMU Wuerzburg & Remeis-Observatory/ECAP), Jonas Hessdoerfer (JMU Wuerzburg), Matthias Kadler (JMU Wuerzburg), George F. Paraschos (MPIfR) & Florian Roesch (JMU Wuerzburg) on behalf of the TELAMON Team
on 4 May 2022; 21:08 UT
Credential Certification: Alexander Plavin (alexander@plav.in)
Subjects: Radio, Neutrinos, AGN, Blazar
The arrival direction of the recently detected high-energy (~604 TeV) neutrino, IceCube GOLD alert 220425A (GCN #31944), coincides with the blazar TXS 1749-101. This blazar was previously selected as an association for another high-energy neutrino event, IceCube EHE alert 181023A (GCN #23375), by Plavin et al. (2020). The neutrino arrival moment coincided with a 2018 radio flare of the blazar. TXS 1749-101 is a gamma-ray source listed in 4FGL, but is not significantly detected by Fermi in the last month, as reported in GCN #31953.
Historical VLBI observations at 2 and 8 GHz demonstrate a distinct core-jet structure at parsec scales. The most recent VLBA observations in 2017 show a compact structure with a core dominance of 75% and core size of 0.4 mas (redshift unknown).
We report that TXS 1749-101 is not showing indications of a major radio flare in 2022. Recent measurements with RATAN-600 and as part of the TELAMON program (Kadler et al. 2021, Proc. ICRC 2021) with the Effelsberg Telescope have delivered the following: the flux density at 11 GHz is 0.28+-0.03 Jy in April 2022 compared to 0.18+-0.02 Jy in December 2021; the flux density at 14 GHz is 0.222+-0.006 Jy on May 2, 2022. Earlier measurements by the RATAN-600 monitoring program indicate a highly variable high-frequency radio emission: flux densities at 22 GHz vary between 0.15 and 0.45 Jy over the last 25 years.
We have triggered monthly RATAN-600 observations (1-22 GHz), as well as follow-up TELAMON observations (14-44 GHz) of the continuum spectrum of TXS 1749-101. We encourage further multi-band observations of the blazar.