Authors

A. Rau, Max-Planck-Instiut für Extraterrestrische Physik, GiessenbachstraßFollow
P. Schady, Max-Planck-Instiut für Extraterrestrische Physik, Giessenbachstraß
J. Greiner, Max-Planck-Instiut für Extraterrestrische Physik, Giessenbachstraß
M. Salvato, Max-Planck-Instiut für Plasma Physik and Excellence Cluster, Boltzmannstrasse & Universe Cluster, Tecnische Universität München, Boltzmannstrasse
M. Ajello, Standford University - WW. Hansen Experimental Physics Laboratory & Kavli Institute for Particle Astrophysics and Cosmology & SLAC National Accelerator Laboratory
E. Bottacini, Standford University - WW. Hansen Experimental Physics Laboratory & Kavli Institute for Particle Astrophysics and Cosmology
N. Gehrels, NASA-Goddard Space Flight Center - Greenbelt, Maryland
P.M. J. Afonso, Max-Planck-Instiut für Extraterrestrische Physik, Giessenbachstraß & American River College - Physics & Astronomy Dept.
J. Elliott, Max-Planck-Instiut für Extraterrestrische Physik, Giessenbachstraß
R Filgas, Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße
D A. Kann, Thüringer Landessternwarte Tautenburg
S Klose, Thüringer Landessternwarte Tautenburg
T Krühler, Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße
M Nardini, Universitá degli studi di Milano-Bicocca
A Nicuesa Guelbenzu, Thüringer Landessternwarte Tautenburg
F Olivares E., Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße
A Rossi, Thüringer Landessternwarte Tautenburg
V Sudilovsky, Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße
A C. Updike, Dickinson College
Dieter H. Hartmann, Clemson UniversityFollow

Document Type

Article

Publication Date

2-2012

Publication Title

Astronomy & Astrophysics

Volume

538

Publisher

EDP Sciences

Abstract

Context.Observations of the γ -ray sky with Fermi led to significant advances towards understanding blazars, the most extreme classof Active Galactic Nuclei. A large fraction of the population detected by Fermi is formed by BL Lacertae (BL Lac) objects, whosesample has always suff ered from a severe redshift incompleteness due to the quasi-featureless optical spectra.Aims.Our goal is to provide a significant increase of the number of confirmed high-redshift BL Lac objects contained in the 2 LACFermi/LAT cataloge.Methods.For 103 Fermi/LAT blazars, photometric redshifts using spectral energy distribution fitting have been obtained. The pho-tometry includes 13 broad-band filters from the far ultraviolet to the near-IR observed with Swift/UVOT and the multi-channel imagerGROND at the MPG/ESO 2.2m telescope. Data have been taken quasi-simultaneously and the remaining source-intrinsic variabilityhas been corrected for. Results.We release the UV-to-near-IR 13-band photometry for all 103 sources and provide redshift constraints for 75 sources withoutpreviously known redshift. Out of those, eight have reliable photometric redshifts at z >1. 3, while for the other 67 sources we pro-vide upper limits. Six of the former eight are BL Lac objects, which quadruples the sample of confirmed high-redshift BL Lac. Thisincludes three sources with redshifts higher than the previous record for BL Lac, including CRATES J0402-2615, with the best-fitsolution at z ≈ 1. 9.

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The published version can be found here: http://www.aanda.org/articles/aa/abs/2012/02/aa18159-11/aa18159-11.html

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