High redshift Fermi blazars observed by GROND and Swift
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.
Keywords
Cite
@article{arxiv.1209.2514,
title = {High redshift Fermi blazars observed by GROND and Swift},
author = {G. Ghisellini and M. Nardini and G. Tagliaferri and J. Greiner and P. Schady and A. Rau and L. Foschini and F. Tavecchio and G. Ghirlanda and T. Sbarrato},
journal= {arXiv preprint arXiv:1209.2514},
year = {2015}
}
Comments
11 pages, 6 figures, submitted to MNRAS