VERITAS observations of AT2021afpi / MASTER OT J030227.28+191754.5 (discovered during follow-up observations of IceCube-211125A)
ATel #15078; John Quinn (University College Dublin) for the VERITAS Collaboration, Brian Metzger (Columbia University), Jeno Sokoloski (Columbia University)
on 30 Nov 2021; 09:48 UT
Credential Certification: John Quinn (john.quinn@ucd.ie)
Subjects: Optical, Gamma Ray, >GeV, TeV, VHE, Neutrinos, Nova
The VERITAS Collaboration reports an upper limit on the very-high-energy (VHE; >100 GeV) gamma-ray flux from the location of AT2021afpi / MASTER OT J030227.28+191754.5, whose discovery was reported in ATel #15067 as a result of follow-up observations of the neutrino candidate IceCube-211125A. VERITAS obtained a 1.5 h exposure on UT20211128 05:46-07:17 and an additional 4.0 h exposure on UT20211129 03:14-07:19. Preliminary analysis of the combined exposures results in no detection, corresponding to a flux upper limit at 99% confidence level of F(>0.24 TeV) ≤ 3.6 × 10-12 cm-2 s-1, or 2% of the Crab Nebula flux.
AT2021afpi was initially classified as a classical He nova (ATel #15069), but is instead likely to be a dwarf nova on the basis of updated optical spectroscopy and detection by Swift XRT (ATels #15072, #15073, #15074).
In the classical nova scenario, AT2021afpi is a possible counterpart to IceCube-211125A. Novae are well established as sources of GeV gamma rays (e.g., Ackermann et al. 2014), and RS Oph was recently detected in the VHE range by H.E.S.S. (ATels #14844, #14857). Classical novae may also be sources of VHE astrophysical neutrinos (e.g., Metzger et al. 2016), particularly early in their evolution.
Questions regarding VERITAS observations should be directed to John Quinn (john.quinn@ucd.ie). VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is located at the Fred Lawrence Whipple Observatory in southern Arizona, USA, and is most sensitive to gamma rays between ∼85 GeV and ∼30 TeV. For further information see the VERITAS web site.
