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.

11 pages, 6 figures, submitted to MNRAS

References in corpus (6)

• GROND - a 7-channel imager
• Swift and infra-red observations of the blazar 3C~454.3 during the giant X-ray flare of May 2005
• INTEGRAL observations of the blazar 3C454.3 in outburst
• Blue Fermi Flat Spectrum Radio Quasars
• SDSS J102623.61+254259.5: the second most distant blazar at z=5.3
• Dissipation of jet bulk kinetic energy in powerful blazars

Cited by in corpus (9)

• SDSS J114657.79+403708.6: the third most distant blazar at z=5.0
• Do high redshift quasars have powerful jets?
• SDSS J013127.34-032100.1: a candidate blazar with a 11 billion solar mass black hole at $z$=5.18
• Constraints on the location of $\gamma$-ray emitting region for a sample of blazars with radio core-shift measurements
• Jets, black holes and disks in blazars
• Awakening of The High Redshift Blazar CGRaBS J0809+5341
• VLBI observations of a flared optical quasar CGRaBS J0809+5341
• Black-hole mass estimation through accretion disk spectral fitting for high-redshift blazars
• Extragalactic astrophysics with next-generation CMB experiments