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arXiv · 1205.1215

On the redshift of the bright BL Lac object PKS 0048-097

Marco Landoni·Renato Falomo·Aldo Treves·Boris Sbarufatti·Roberto Decarli·Fabrizio Tavecchio·Jari Kotilainen
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Abstract

Aims: The determination of elusive redshifts of bright BL Lac objects Methods: We use the capabilities of newly available spectrograph X-Shooter at European Southern Observatory (ESO) Very Large Telescope, that combines high resolution and a large wavelength range, to obtain UVB to near-IR spectra of BL Lacs. Results: Our observations of PKS 0048-097 detect three emission lines that permit to derive a redshift z = 0.635. Moreover, a Mg II absorption system at z = 0.154 that is associated with a foreground spiral galaxy at 50 Kpc projected distance is found. Conclusions: The obtained redshift allows us to comment about the optical beaming factor and the absorption of the high energy spectrum by the Extragalactic Background Light.

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Marco Landoni, Renato Falomo, Aldo Treves, Boris Sbarufatti, Roberto Decarli, Fabrizio Tavecchio, Jari Kotilainen. 2012-05-06. On the redshift of the bright BL Lac object PKS 0048-097. https://doi.org/10.1051/0004-6361%2F201219114

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