The redshift of 4FGLJ0955.1+3551 (3HSPJ095507.1+355100): a possible counterpart of the neutrino event IceCube-200107A
ATel #13457; Simona Paiano (INAF/OA Roma - IASF Milano ), Renato Falomo (INAF/OAPD), Aldo Treves (Universitaâ dellâInsubria, INAF/OA Brera), Paolo Padovani (ESO), Paolo Giommi (ASI), Adriana Gargiulo (INAF/IASF Milano), Andrea Rossi (INAF/OAS Bologna)
on 7 Feb 2020; 10:45 UT
Credential Certification: Simona Paiano (simona.paiano@inaf.it)
Subjects: Optical, Gamma Ray, Neutrinos, Blazar
IceCube-200107A is a high energy neutrino event of potential astrophysical interest (GCN#26655). The most likely association inside the error region of the event appears to be with 4FGLJ0955.1+3551 (3HSPJ095507.1+355100), a bright X-ray and gamma-ray BL Lac object. A Swift ToO, performed shortly after the neutrino arrival, revealed the source at its highest X-ray flux ever recorded (Atel#13394). On January 29, 2020 we obtained a spectrum of the target at the Large Binocular Telescopes (two twin 8.4m telescopes at Mt Graham, Arizona) using the spectrographs MODS-1,2 (exposure 3 hrs, spectral range 3200-10000 Ang, spectral resolution~1000). The spectrum clearly exhibits absorption features due to Ca II doublet, G-band, Mg I of the host galaxy. This allows us to derive a firm redshift of 0.557.
We thank the LBT staff for the observations and in particular Steve Allanson for the excellent support.
