South Pole Telescope Follow-up of IceCube-190331A
ATel #12735; N. Whitehorn (UCLA) and L. Bleem (Argonne National Laboratory) on behalf of the SPT Collaboration
on 7 May 2019; 17:37 UT
Credential Certification: Nathan Whitehorn (nwhitehorn@physics.ucla.edu)
Subjects: Millimeter, Neutrinos, Transient
We report on millimeter-band follow-up with the SPT-3G receiver on the South Pole Telescope (SPT) of the high-energy neutrino IC190331A detected on March 31, 2019 by IceCube (ATEL #12616). The neutrino was detected by IceCube at J2000 position RA = 337.68 (+0.23, -0.34) deg and Dec = -20.70 (+0.30, -0.48) deg, with uncertainties indicating 90% containment.
In observations of a 3x4 degree field centered on the neutrino position taken on April 12, 2019, we detect no sources in the 90% containment region reported by IceCube with map depths of 4.2, 4.3, and 19.8 mJy/beam at bands centered at 95, 150, and 220 GHz, respectively. Analysis of archival data taken over a longer period in late 2015 and early 2016 with the earlier SPTpol instrument also detects no sources in the 90% containment region with map depths of 3.2 and 1.8 mJy/beam at 95 and 150 GHz, respectively (SPTpol did not have a 220 GHz channel).
Three sources are detected in the full 3x4 degree patch. The only one potentially associated with the neutrino source is at a position of RA = 338.740d, Dec = -20.918d, +/- 3 arcsec (stat. + syst.), one degree from the best-fit neutrino position, and tentatively identified as the distant blazar QSO B2232-211. In our data, it has fluxes of 73.1 +/- 4.2, 56.2 +/- 4.3, and 67.7 +/- 19.8 mJy in bands centered at 95, 150, 220 GHz, consistent with a spectral index of -0.5. Analysis of archival 150 GHz data gives a flux of 66.7 +/- 1.8 mJy in late 2015/early 2016, slightly brighter than the 2019 data, giving no evidence of a high-emission state at the time of the neutrino observation.
All flux calibrations quoted here are preliminary and are believed to be accurate to 15%. Calibration uncertainties on the 2019 data taken with SPT-3G and the 2015/2016 data taken with SPTpol are independent.
The South Pole Telescope is a 10-meter CMB telescope at Amundsen-Scott South Pole Station supported by the National Science Foundation (PLR-1248097) and the US Dept. of Energy. The analysis in this telegram is supported by NSF grant AST-1716965 (UCLA) and by UChicago Argonne LLC, Operator of Argonne National Laboratory (Argonne). Argonne, a U.S. Department of Energy Office of Science Laboratory, is operated under contract no. DE-AC02-06CH11357.
