2024/05/17 by S. Paiano, R. Falomo, Paiano, Simona +7 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · pdf · doi:10.48550/arxiv.2405.10684
openalex publication_date 2024/05/17 · openalex created_date 2024/05/21 · openalex updated_date 2026/07/28
Following the high activity of the gamma-ray Fermi source 4FGL J0449.1+1121 (PKS 0446+112), possibly associated with a IceCube neutrino event IC-240105A, we obtained optical spectroscopy with the Gran Telescopio Canarias of the counterpart. We detect a clear emission line at 3830 Ang identified as Lyα that confirms the redshift of source at z=2.153. Comparing with previous spectroscopy, we find an increase of the continuum by a factor ∼10, and a significant decrease of the CIV 1550 emission line flux by a factor ∼5. This produces a dramatic drop of the Equivalent Width from ∼20 Ang to 0.8 Ang, which is suggestive of a very high jet activity. The Full Width Half Maximum of the emission lines are midway (1000 - 2000 km/s) between those typical of the broad and narrow regions of quasars. Based on this, the source classification is intermediate between Flat Spectrum Radio Quasar and BL Lac object.