The broad-band X-ray spectrum of the blazar PKS B1830-211 by Chandra and INTEGRAL

¹ IASF - Sezione di Roma, INAF, via del Fosso del Cavaliere 100, 00113 Roma, Italy e-mail: derosa@rm.iasf.cnr.it
² Dipartimento di Fisica, Università La Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
³ Geneva Observatory, INTEGRAL Science Data Centre, Chemin d'Ecogia 16, 1291 Versoix, Switzerland
⁴ IASF - Sezione di Bologna, INAF, via P. Gobetti 101, 40129 Bologna, Italy
⁵ School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ, UK

Received: 17 January 2005
Accepted: 5 April 2005

Abstract

In this paper we present a broad-band study of the X-ray emission of the blazar PKS 1830-211 based on Chandra and INTEGRAL observations. Notwithstanding the high redshift (), it is a bright X-ray source (F(2–10 keV)  erg cm^-2 s^-1), due to gravitational lensing by an intervening galaxy at . Previous X-ray observations attribute the observed absorption at  keV to the lensing galaxy. Our analysis, although not in contrast with this hypothesis, suggests also the possibility of an intrinsic (ionized) absorption, taking place at the front side of the jet. This scenario is also supported by some evidence, in the same data, of a feature observed at 2.15 keV which can be interpreted as a blueshifted iron line (). The SED of PKS 1830-211 can be well modelled by combining a Synchrotron Self-Compton component and an external source of photons to be scattered up to γ-ray energies by relativistic electrons moving outward in the jet. The main source of low energy photons is a dust torus at the temperature of 10³ K as expected in MeV blazars.