Two bright blazars located close to the IceCube-241224A neutrino are found to flare in radio band
ATel #16992; Y. Y. Kovalev (MPIfR), A. V. Plavin (Harvard U.), S. V. Troitsky (INR RAS), Yu. A. Kovalev (ASC Lebedev), A. V. Popkov (MIPT), Yu. V. Sotnikova (SAO), A. K. Erkenov (SAO)
on 23 Jan 2025; 14:27 UT
Credential Certification: Yuri Y. Kovalev (yykovalev@gmail.com)
Subjects: Radio, Neutrinos, AGN, Blazar, Quasar
IceCube collaboration has recently detected a neutrino event IceCube-241224A, which has two blazars with bright and compact parsec-scale jets close to its arrival direction. They are located at distances 0.70 deg (1217+023 or J1220+0203) and 1.46 deg (1222+037 or J1224+0330) from the best-fit reconstructed neutrino direction. Gamma-ray emission from J1220+0203 was discussed in ATEL #16987.
We have organized radio observations of both of these targets with RATAN-600 at 2-22 GHz immediately after the IceCube announcements. Both of these targets were found in a flaring state, compared to our historical measurements.
J1220+0203 is experiencing a 1-2 year long flare, reaching 0.85 Jy at 22 GHz at the end of 2024 with decrease afterwards, now close to its typical flux level of 0.4 Jy. The flare is still developing at lower frequencies, reaching its peak at 8-11 GHz in January 2025.
J1224+0330 is experiencing a major decade-long flare since 2013 with the peak of 1.7 Jy at 22 GHz in 2021-2022, now slowly decreasing back to the quiescent level of 0.4 Jy. Flares at lower frequencies, 2-11 GHz, are also on the declining stage as of January 2025.
We have triggered VLBA monitoring observations at 15, 24, and 43 GHz of both of these targets, in order to probe changes in their parsec-scale properties, potentially associated with the neutrino production. Other follow up observations are encouraged.