Journal Article

Extended X-ray emission in the high-redshift quasar GB 1508+5714 at <i>z</i> = 4.3

W. Yuan, A. C. Fabian, A. Celotti and P. G. Jonker

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 346, issue 1, pages L7-L10
Published in print November 2003 | ISSN: 0035-8711
Published online November 2003 | e-ISSN: 1365-2966 | DOI:
Extended X-ray emission in the high-redshift quasar GB 1508+5714 at z = 4.3

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We report the discovery of extended X-ray emission around the powerful high-redshift quasar GB 1508+5714 at z= 4.3, revealed in a long Chandra ACIS observation. The emission feature is 3–4 arcsec away from the quasar core, which corresponds to a projected distance of about 25 kpc. The X-ray spectrum is best fitted with a power law of photon index 1.92 ± 0.35 (90 per cent confidence limit). The X-ray flux and luminosity reach 9.2 × 10−15 erg cm−2 s−1 (0.5–8 keV) and 1.6 × 1045 erg s−1 (2.7–42.4 keV rest frame, ΩΛ= 0.73, Ωm= 0.27, H0= 71 km s−1 Mpc−1), which is about 2 per cent of the total X-ray emission of the quasar. We interpret the X-ray emission as inverse Compton scattering of cosmic microwave background photons. The scattering relativistic electron population could either be a quasi-static diffuse cloud fed by the jet, or an outer extension of the jet with a high bulk Lorentz factor. We argue that the lack of an obvious detection of radio emission from the extended component could be a consequence of Compton losses on the electron population, or of a low magnetic field. Extended X-ray emission produced by inverse Compton scattering may be common around high-redshift radio galaxies and quasars, demonstrating that significant power is injected into their surroundings by powerful jets.

Keywords: radiation mechanisms: non-thermal; galaxies: active; galaxies: jets; quasars: individual: GB 1508+5714; X-rays: galaxies

Journal Article.  2866 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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