Optical spectroscopy of 4FGLJ0258.1+2030: possible counterpart of the two neutrino events IceCube-191231A and IceCube-211125A
ATel #15085; Simona Paiano (INAF/OAR, INAF/IASF-PA) , Aldo Treves (Universitaâ dellâInsubria, INAF/OABrera), Renato Falomo (INAF/OAPD), Paolo Padovani (ESO), Paolo Giommi (ASI), Riccardo Scarpa (IAC, Universidad de la Laguna)
on 5 Dec 2021; 11:07 UT
Credential Certification: Simona Paiano (simona.paiano@inaf.it)
Subjects: Optical, Gamma Ray, Neutrinos, Blazar
A plausible association inside the error box of the two neutrino events, IceCube-191231A (GCN#26620) and IceCube-211125A (GCN#31126), is the gamma-ray source 4FGLJ0258.1+2030 (MG3J025805+2029). After the second event the associated radio source was detected at a substantially higher flux densities than listed in the RFC catalog (ATEL#15706). The source was proposed as a BL Lacertae object in the BZCAT catalog (Massaro et al., Ap&SS, 357, 75).
On 2020 October 08, we obtained an optical spectrum in the range 5000 - 7700 Ang (average S/N ~ 60) of the target (observed g = 21.0, apparent and corrected for extinction r = 17.6 ) at the Gran Telescopio Canarias (10.4 m), using the spectrograph OSIRIS (exposure time = 9000 sec). The spectrum is severely reddened due to galactic extinction ( E(B-V)=1.1 ).
The dereddened optical spectrum (see below for the link to the spectrum) is characterized by a featureless continuum described by a power-law shape that confirms the BL Lac classification of the target.
No emission lines with Equivalent Width EW > 0.8 Ang are found.
From the absence of the absorption lines of the host galaxy, assumed to be a giant elliptical of M(R) -22.9 (Sbarufatti et al., 2005, ApJ, 635, 173), we obtain the redshift lower limit (see details in Paiano et al, 2017, ApJ, 837, 144) of z > 0.3.
The spectrum is available in the spectroscopic database ZBLLAC (https://web.oapd.inaf.it/zbllac/).
4FGLJ0258p2030_GTC_spectrum
