Constraints on the average magnetic field strength of relic radio sources 0917+75 and 1401−33 from XMM–Newton observations

• Published in: Monthly notices of the Royal Astronomical Society Vol. 383; no. 3; pp. 1259 - 1268
• Main Authors: Chen, C. M. Hubert, Harris, D. E., Harrison, Fiona A., Mao, Peter H.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2008; Blackwell Science; Oxford University Press
• Subjects: Astronomy; Astrophysics; Cosmic background radiation; Earth, ocean, space; Exact sciences and technology; galaxies: magnetic fields; Magnetic fields; radiation mechanisms: non-thermal; Radio astronomy; radio continuum: galaxies; X-ray astronomy; X-rays: galaxies; radiation mechanisms: non-thermal; galaxies: magnetic fields; X-rays: galaxies; radio continuum: galaxies; Lower bound; X ray observation; X-ray galaxies; Radio galaxies; Cosmic background radiation; Cosmic x-ray sources; Relativistic electron; Radio observation; Nonthermal radiation; Continuum; Upper bound; Inverse Compton scattering; Cosmic radio sources; Magnetic fields; X ray emission
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2007.12633.x

We observed two relic radio sources, 0917+75 and 1401−33, with the XMM–Newton X-ray observatory. We did not detect any X-ray emission, thermal or non-thermal, in excess of the local background level from either target. This imposes new upper limits on the X-ray flux due to inverse Compton scattering of photons from the cosmic microwave background by relativistic electrons in the relic sources, and new lower limits on the magnetic field strength from the relative strength of the radio and X-ray emission. The combination of radio and X-ray observations provides a measure of the magnetic field independent of equipartition or minimum energy assumptions. Due to increasing sensitivity of radio observations, the known population of cluster relics has been growing; however, studies of non-thermal X-ray emission from relics remain scarce. Our study adds to the small sample of relics studied in X-rays. In both relics, our field strength lower limits are slightly larger than estimates of the equipartition magnetic field.