Multiwavelength Observations of the Powerful γ-ray Quasar PKS 1510−089: Clues on the Jet Composition

We present the results from a multiwavelength campaign conducted in August 2006 of the powerful γ-ray quasar PKS 1510−089 (z = 0.361). This campaign commenced with a deep Suzaku observation lasting three days for a total exposure time of 120 ks, and continued with Swift monitoring over 18 days. Besides Swift observations, which sampled the optical/UV flux in all 6 UVOT filters as well as the X-ray spectrum in the 0.3−10 keV energy range, the campaign included ground-based optical and radio data, and yielded a quasi-simultaneous broad-band spectral energy distribution from 10 Hz to 10 Hz. Thanks to its low instrumental background, the Suzaku observation provided a high S/N X-ray spectrum, which is well represented by an extremely hard power-law with photon index Γ≃ 1.2, augmented by a soft component apparent below 1 keV, which is well described by a black-body model with temperature kT ≃ 0.2 keV. Monitoring by Suzaku revealed temporal variability which is different between the low and high energy bands, again suggesting the presence of a second, variable component in addition to Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan Stanford Linear Accelerator Center and Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716, Warsaw, Poland Department of Astronomy and Astrophysics, Pennsylvania State University, PA, 16802, USA Physics Department and Astronomical Observatory, University of Perugia, Perugia, Italy Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany Astro Space Center of the Lebedev Physical Institute, Profsoyuznaya 84/32, Moscow, 117997, Russia Australia Telescope National Facility, CSIRO, Locked Bag 194, Narrabri NSW 2390, Australia Landessternwarte Heidelberg, Kőnigstuhl, D-69117 Heidelberg, Germany Astronomical Observatory of the Jagiellonian University, ul. Orla 171, 30-244 Kraków, Poland Department of High Energy Astrophysics, ISAS, JAXA, Kanagawa, 229-8510, JAPAN SLAC-PUB-12839 arXiv:0709.1528[astro-ph] September 2007 Submitted to Astrophysical Journal