Emission-line variability during a nonthermal outburst in the gamma-ray bright quasar 1156+295
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Date
2022-02-01
Authors
Hallum, Melissa K.
Jorstad, Svetlana G.
Larionov, Valeri M.
Marscher, Alan P.
Joshi, Manasvita
Weaver, Zachary R.
Williamson, Karen E.
Agudo, Iván
Borman, G.A.
Casadio, Carolina
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OA Version
Published version
Citation
M.K. Hallum, S.G. Jorstad, V.M. Larionov, A.P. Marscher, M. Joshi, Z.R. Weaver, K.E. Williamson, I. Agudo, G.A. Borman, C. Casadio, A. Fuentes, T.S. Grishina, E.N. Kopatskaya, E.G. Larionova, L.V. Larionova, D.A. Morozova, A.A. Nikiforova, S.S. Savchenko, I.S. Troitsky, Y.V. Troitskaya, A.A. Vasilyev. 2022. "Emission-line Variability during a Nonthermal Outburst in the Gamma-Ray Bright Quasar 1156+295" The Astrophysical Journal: an international review of astronomy and astronomical physics, Volume 926, Issue 2, pp.180-180. https://doi.org/10.3847/1538-4357/ac4710
Abstract
We present multi-epoch optical spectra of the γ-ray bright blazar 1156+295 (4C +29.45, Ton 599) obtained with the 4.3 m Lowell Discovery Telescope. During a multiwavelength outburst in late 2017, when the γ-ray flux increased to 2.5 × 10−6 phot cm−2 s−1 and the quasar was first detected at energies ≥100 GeV, the flux of the Mg ii
λ2798 emission line changed, as did that of the Fe emission complex at shorter wavelengths. These emission-line fluxes increased along with the highly polarized optical continuum flux, which is presumably synchrotron radiation from the relativistic jet, with a relative time delay of ≲2 weeks. This implies that the line-emitting clouds lie near the jet, which points almost directly toward the line of sight. The emission-line radiation from such clouds, which are located outside the canonical accretion-disk related broad-line region, may be a primary source of seed photons that are up-scattered to γ-ray energies by relativistic electrons in the jet.
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© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.