EDP Sciences
Free Access
Issue
A&A
Volume 414, Number 3, February II 2004
Page(s) L41 - L44
Section Letters
DOI https://doi.org/10.1051/0004-6361:20031749
Published online 27 January 2004


A&A 414, L41-L44 (2004)
DOI: 10.1051/0004-6361:20031749

Letter

Is there a hard tail in the Coma Cluster X-ray spectrum?

M. Rossetti1, 2 and S. Molendi1

1  Istituto di Astrofisica Spaziale e Fisica Cosmica, via Bassini 15, 20133 Milano, Italy
2  Università degli Studi di Milano, Dip. di Fisica, via Celoria 16, 20133 Milano, Italy

(Received 30 September 2003 / Accepted 17 December 2003)

Abstract
We report results from a re-analysis of the BeppoSAX observation of Coma and from the analysis of a second, yet unpublished observation of the same object. From our re-analysis of the first observation we find that the statistical evidence for a hard tail is about 2 $\sigma$. From the analysis of the second observation which, thanks to the lower background and the longer exposure time, is characterized by a larger signal-to-noise we find no evidence for a hard tail. From the upper limit on the flux of the hard tail, using the standard Inverse Compton formulae, we derive a lower limit for the magnetic of ${\sim} 0.2{-}0.4\ \mu\rm {Gauss}$ consistent with Faraday rotation measurements.


Key words: cosmic microwave background -- galaxies: clusters: individual: Coma -- magnetic field -- radiation mechanism: non-thermal -- X-rays: galaxies: clusters

Offprint request: M. Rossetti, rossetti@mi.iasf.cnr.it

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© ESO 2004

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