We report results of a spectroscopic campaign carried out at the 10 m Gran Telescopio Canarias for a sample of 22 BL Lac objects detected (or candidates) at TeV energies, aiming to determine or constrain their redshift. This is of fundamental importance for the interpretation of their emission models and for population studies and is also mandatory for studying the interaction of high-energy photons with the extragalactic background light using TeV sources. Optical spectra with high signal-to-noise ratios in the range 4250-10000 Ã were obtained to search for faint emission or absorption lines from both the host galaxy and the nucleus. We determine a new redshift for PKS 1424+240 (z = 0.604) and a tentative one for 1ES 0033+595 (z = 0.467). ...
Abstract: The BL-Lac blazar PKS 0447-439 was detected at very high energy gamma-rays by HESS followi...
We report on 16 BL Lacertae objects that were proposed to be at z > 1. We present spectroscopic obse...
Context. BL Lac objects detected in γ-rays and, particularly, those detected at very high energies (...
We report results of a spectroscopic campaign carried out at the 10 m Gran Telescopio Canarias for a...
Aims. We aim to determine the redshift (or stringent lower limits) of a number of bright BL Lacs obj...
We present optical spectra with high signal-to-noise ratio of 10 BL Lac objects detected at GeV ener...
<p>We carried out an extensive spectroscopic campaign of blazars of unknown or uncertain redshift wh...
Context. The study of BL Lac objects (BLL) detected in gamma-rays gives insights on the acceleration...
Context. The study of BL Lac objects (BLL) detected in gamma-rays gives insights on the acceleration...
The Fermi Gamma-ray Observatory discovered about a thousand extragalactic sources emitting energy fr...
Context. Blazars are the most numerous class of high-energy (HE; E ∼ 50 MeV−100 GeV) and very high-e...
The TeV emission of low power BL Lac objects has been established by the detection of an handful of ...
Aims.We present optical spectroscopy for a sample of BL Lac objects, to determine their redshift, t...
Context.BL Lacertae objects have been the targets for numerous recent multiwavelength campaigns, con...
Context. Blazars are the most numerous class of High Energy (HE; E ~50 MeV – few 100 GeV) and Very H...
Abstract: The BL-Lac blazar PKS 0447-439 was detected at very high energy gamma-rays by HESS followi...
We report on 16 BL Lacertae objects that were proposed to be at z > 1. We present spectroscopic obse...
Context. BL Lac objects detected in γ-rays and, particularly, those detected at very high energies (...
We report results of a spectroscopic campaign carried out at the 10 m Gran Telescopio Canarias for a...
Aims. We aim to determine the redshift (or stringent lower limits) of a number of bright BL Lacs obj...
We present optical spectra with high signal-to-noise ratio of 10 BL Lac objects detected at GeV ener...
<p>We carried out an extensive spectroscopic campaign of blazars of unknown or uncertain redshift wh...
Context. The study of BL Lac objects (BLL) detected in gamma-rays gives insights on the acceleration...
Context. The study of BL Lac objects (BLL) detected in gamma-rays gives insights on the acceleration...
The Fermi Gamma-ray Observatory discovered about a thousand extragalactic sources emitting energy fr...
Context. Blazars are the most numerous class of high-energy (HE; E ∼ 50 MeV−100 GeV) and very high-e...
The TeV emission of low power BL Lac objects has been established by the detection of an handful of ...
Aims.We present optical spectroscopy for a sample of BL Lac objects, to determine their redshift, t...
Context.BL Lacertae objects have been the targets for numerous recent multiwavelength campaigns, con...
Context. Blazars are the most numerous class of High Energy (HE; E ~50 MeV – few 100 GeV) and Very H...
Abstract: The BL-Lac blazar PKS 0447-439 was detected at very high energy gamma-rays by HESS followi...
We report on 16 BL Lacertae objects that were proposed to be at z > 1. We present spectroscopic obse...
Context. BL Lac objects detected in γ-rays and, particularly, those detected at very high energies (...