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Issue A&A
Volume 422, Number 1, July IV 2004
Page(s) 77 - 84
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20034451



A&A 422, 77-84 (2004)
DOI: 10.1051/0004-6361:20034451

Highly ionized Fe K $\alpha$ emission lines from the LINER galaxy M 81

M. J. Page, R. Soria, S. Zane, K. Wu and R. L. C. Starling

Mullard Space Science Laboratory, University College London, Holmbury St Mary, Surrey RH5 6NT, UK

(Received 6 October 2003 / Accepted 8 April 2004)

Abstract
We present spectral and timing results from a long (130 ks) XMM-Newton EPIC observation of the nucleus of the Seyfert/LINER galaxy M 81. During the observation the X-ray flux varied by 20%, but there was no significant change in spectral shape. The 2-10 keV spectrum is well described by a power law continuum and three narrow Fe K $\alpha$ emission lines at 6.4, 6.7 and 6.96 keV. The three emission lines have equivalent widths of 39+13-12, 47+13-13 and 37+15-15 eV respectively. The ratios of the three lines are thus more similar to those observed from the Galactic Centre region than to those typically observed from Seyfert galaxies. The high ionization lines most likely originate either from photoionized gas within 0.1 pc of the nucleus of M 81, or from a non-thermal distribution of cosmic-ray electrons interacting with the 0.2-0.6 keV thermal plasma which is found in the bulge of M 81.


Key words: galaxies: individual: M 81 (=NGC 3031) -- galaxies: nuclei -- galaxies: Seyfert -- galaxies: active -- X-rays: galaxies

Offprint request: M. J. Page, mjp@mssl.ucl.ac.uk

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