SRG/eROSITA detection of 4FGL J0658.6+0636 prior to high-energy neutrino alert IceCube-201114A
ATel #14199; Andrea Gokus (Remeis Observatory/ECAP & University of Wuerzburg), Steven Haemmerich (Remeis Observatory/ECAP), Arne Rau (MPE Garching), Joern Wilms (Remeis Observatory/ECAP)
on 19 Nov 2020; 09:46 UT
Credential Certification: Arne Rau (arau@mpe.mpg.de)
The eROSITA instrument (Predehl et al., arXiv:2010.03477) onboard the Russian/German SRG mission scanned over the location of 4FGL J0658.6+0636, the Fermi-LAT cataloged source positionally coincident with the high-energy neutrino alert IceCube-201114A (GCN #28887), as part of its ongoing second all-sky survey (eRASS:2). Observations were performed between October 16, 2020 04:10 UTC and October 17, 2020 00:10 UTC, 28 days prior to the IceCube neutrino detection.
Using a total of 135 seconds on-target exposure, we detect an X-ray source at RA(J2000)= 104.686818 deg, Decl(J2000) = 6.619607 deg with a positional uncertainty of 5" (incl. systematics). This is consistent with the position of 4FGL J0658.6+0636.
The X-ray spectrum includes 83 photons and is best fit with an absorbed power law with a photon index of 2.0+/-0.5 and a fixed neural hydrogen absorption column density of N_H = 2.9 x 10^21/cm^2 (HI4PI Collaboration, N. Ben Bekhti, L. Floer, et al., 2016, Astronomy & Astrophysics, 594, A116). The resulting 0.3-10keV flux is (4.7 +1.8, -1.2) x 10^-12 erg/cm^2/s.
The source has been also been detected during the first eROSITA all-sky survey (eRASS:1) between April 12, 2020 21:49 UTC and April 13, 2020 13:49 UTC. Fitting the same model to those data, the best fit yields a photon index of 1.3+/-0.9 and a 0.3-10keV flux of (1.7 +2.4, -0.9) x 10^-12 erg/cm^2/s.
Comparing the results from eROSITA with those of the Swift/XRT observation obtained on 2020 November 15th and reported in ATel #14178 shows, that 4FGL J0658.6+0636 has brightened by a factor of ~20 over this 29 days period.
