1. High-redshift Fermi blazars observed by GROND and Swift
- Author
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Giancarlo Ghirlanda, Gabriele Ghisellini, Arne Rau, Luigi Foschini, Jochen Greiner, Marco Nardini, G. Tagliaferri, Patricia Schady, Tullia Sbarrato, Fabrizio Tavecchio, Ghisellini, G, Nardini, M, Tagliaferri, N, Greiner, J, Schady, P, Rau, A, Foschini, L, Tavecchio, F, Ghirlanda, G, and Sbarrato, T
- Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Swift Gamma-Ray Burst Mission ,Astrophysics::High Energy Astrophysical Phenomena ,galaxies: active ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,law.invention ,Telescope ,FIS/05 - ASTRONOMIA E ASTROFISICA ,law ,Astrophysics::Solar and Stellar Astrophysics ,Blazar ,Astrophysics::Galaxy Astrophysics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Astronomy ,Astronomy and Astrophysics ,Quasar ,radiation mechanisms: non-thermal ,galaxies: jets ,Redshift ,Black hole ,Space and Planetary Science ,Spectral energy distribution ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Fermi Gamma-ray Space Telescope - Abstract
We observed 5 gamma-ray loud blazars at redshift greater than 2 with the X-Ray Telescope (XRT) and the UltraViolet and Optical Telescope (UVOT) onboard the Swift satellite, and the Gamma-Ray burst Optical Near-Infrared Detector (GROND) instrument. These observations were quasi simultaneous, usually within a few hours. For 4 of these blazars the near-IR to UV data show the presence of an accretion disc, and we could reliably estimate its accretion rate and black hole mass. One of them, PKS 1348+007, was found in an extraordinarily high IR-optical state, almost two orders of magnitude brighter than at the epoch of the Sloan Digital Sky Survey observations. For all the 5 quasars the physical parameters of the jet emitting zone, derived by applying a one-zone emission model, are similar to that found for the bulk of other gamma-ray loud quasars. With our observations we have X-ray data for the full sample of blazars at z>2 present in the Fermi 2-yrs (2LAC) catalog. This allows to have a rather complete view of the spectral energy distribution of all high-redshift Fermi blazars, and to draw some conclusions about their properties, and especially about the relation between the accretion rate and the jet power., 11 pages, 6 figures, submitted to MNRAS
- Published
- 2012