Changing Look of the optical spectrum of the MeV Blazar PKS 0446+112 (4FGL J0449.1+1121)

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Hauptverfasser: Paiano, Simona, Falomo, Renato, Treves, Aldo, Scarpa, Riccardo, Sbarufatti, Boris
Format: Preprint
Veröffentlicht: 2024
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author Paiano, Simona
Falomo, Renato
Treves, Aldo
Scarpa, Riccardo
Sbarufatti, Boris
author_facet Paiano, Simona
Falomo, Renato
Treves, Aldo
Scarpa, Riccardo
Sbarufatti, Boris
contents 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 Ly$α$ that confirms the redshift of source at z=2.153. Comparing with previous spectroscopy, we find an increase of the continuum by a factor $\sim$10, and a significant decrease of the CIV 1550 emission line flux by a factor $\sim$5. This produces a dramatic drop of the Equivalent Width from $\sim$20 Ang to 0.8 Ang, which is suggestive of a very high jet activity. The Full Width Half Maximum of the emission lines are midway (1000 - 2000 km/s) between those typical of the broad and narrow regions of quasars. Based on this, the source classification is intermediate between Flat Spectrum Radio Quasar and BL Lac object.
format Preprint
id arxiv_https___arxiv_org_abs_2405_10684
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Changing Look of the optical spectrum of the MeV Blazar PKS 0446+112 (4FGL J0449.1+1121)
Paiano, Simona
Falomo, Renato
Treves, Aldo
Scarpa, Riccardo
Sbarufatti, Boris
High Energy Astrophysical Phenomena
Astrophysics of Galaxies
Following the high activity of the gamma-ray Fermi source 4FGL J0449.1+1121 (PKS 0446+112), possibly associated with a IceCube neutrino event IC-240105A, we obtained optical spectroscopy with the Gran Telescopio Canarias of the counterpart. We detect a clear emission line at 3830 Ang identified as Ly$α$ that confirms the redshift of source at z=2.153. Comparing with previous spectroscopy, we find an increase of the continuum by a factor $\sim$10, and a significant decrease of the CIV 1550 emission line flux by a factor $\sim$5. This produces a dramatic drop of the Equivalent Width from $\sim$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.
title Changing Look of the optical spectrum of the MeV Blazar PKS 0446+112 (4FGL J0449.1+1121)
topic High Energy Astrophysical Phenomena
Astrophysics of Galaxies
url https://arxiv.org/abs/2405.10684