PKS 0447-439 is one of the BL Lacertae objects that have been detected at very high energy. There has been a recent report of a lower limit of z ≥ 1.246 for the redshift of this blazar, challenging the current paradigm in which very high-energy γ-rays cannot freely propagate in the z ≥ 1 universe. In this research note, we present a new MagE/Magellan spectrum of PKS 0447-439 with exquisite signal-to-noise (S/N > 150 at 6500 Å). Our analysis confirms the presence of the previously-reported absorption line at 6280 Å, which we identify, however, with a known telluric absorption, invalidating the claim that this blazar lies at z > 1. Since no other extragalactic spectral features are detected, we cannot establish a redshift based on our spectrum. © ESO, 2012.

Fumagalli, M., Furniss, A., O'Meara, J., Prochaska, J., Williams, D., & Farina, E. (2012). On the redshift of the blazar PKS 0447-439. ASTRONOMY & ASTROPHYSICS, 545, A68 [10.1051/0004-6361/201220022].

On the redshift of the blazar PKS 0447-439

Fumagalli M.;
2012

Abstract

PKS 0447-439 is one of the BL Lacertae objects that have been detected at very high energy. There has been a recent report of a lower limit of z ≥ 1.246 for the redshift of this blazar, challenging the current paradigm in which very high-energy γ-rays cannot freely propagate in the z ≥ 1 universe. In this research note, we present a new MagE/Magellan spectrum of PKS 0447-439 with exquisite signal-to-noise (S/N > 150 at 6500 Å). Our analysis confirms the presence of the previously-reported absorption line at 6280 Å, which we identify, however, with a known telluric absorption, invalidating the claim that this blazar lies at z > 1. Since no other extragalactic spectral features are detected, we cannot establish a redshift based on our spectrum. © ESO, 2012.
Si
Articolo in rivista - Articolo scientifico
Scientifica
BL Lacertae objects: individual: PKS0447-439; Galaxies: active; Galaxies: distances and redshifts
English
A68
Fumagalli, M., Furniss, A., O'Meara, J., Prochaska, J., Williams, D., & Farina, E. (2012). On the redshift of the blazar PKS 0447-439. ASTRONOMY & ASTROPHYSICS, 545, A68 [10.1051/0004-6361/201220022].
Fumagalli, M; Furniss, A; O'Meara, J; Prochaska, J; Williams, D; Farina, E
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/10281/280713
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