1. The unusual X-ray spectrum of MCG-2-58-22
-as seen by XMM-Newton and BeppoSAX
N.Salvi, A Orr, M.Page, K.Mason, P.Barr, M. Guainazzi, A. Parmer,
M. Santos-Lleo, R. Staubert
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We present preliminary results from combined XMM-Newton and BeppoSAX spectroscopy of the luminous Seyfert I galaxy MCG Previous high energy observations of this source were not able to determine whether the underlying X-ray continuum in the source is intrinsically flat or whether the spectral hardness is in fact due to the presence of a reflection component.
Low level X-ray variability is seen during the long BeppoSAX observation. The light curves from both instruments, LECS ( keV) and MECS (2-10 keV) show variations in X-ray flux. The largest changes in count rate are 27  (MECS) and 42 (LECS) within 7000 sec (Fig 4).
Our new data set shows that the spectrum between keV is indeed hard and can be well represented by a power-law continuum ( =1.6) and Fe K line emission (6.6 keV). We find that reflection contributes very little to the continuum spectrum of MCG The upper limit to the reflection fraction is 16% at 90% confidence. The ionization parameter is low with  < 30 ergs cm s-1 (Fig 2)
Fig 4. The light curves and hardness ratio for the long BeppaSAX exposure. The length of the XMM Observation is marked in green.
Fig 1. Simultaneous broken powerlaw model fit to the BeppoSAX (LECS, MECS, PDS) and XMM (RGS, MOS) data (0.1-2 = 1.8, 2-100 = 1. 6 , Ebreak = 2.3 keV). The residuals show an Fe line at 6.6 keV and a complex low energy spectrum.
Fig 2. Contour plot illustrating the fit of a reflection model to the combined XMM+SAX data ( keV: MOS + RGS + LECS + MECS + PDS). The plot shows the confidence contours for the reflection fraction, R (Model = Incident + R * Reflected) and log () the ionization parameter (defined between keV)
The XMM-Newton EPIC keV and 2-10 keV light curves do not exhibit significant flux variations during the 10 ks exposure (Fig 5).
The high resolution and sensitivity of the XMM-Newton RGS and EPIC-MOS detectors show a complex low energy spectrum (E < 2 keV) with line and/or continuum flux in excess of the underlying powerlaw. The low energy residuals remain even with the addition of a black body excess. The soft X-ray features can be well described by relativistic O VIII, N VII and C VI lines (Fig 3). The goodness of fit is improved at  99 confidence level when the lines are added to the powerlaw model.
Fig 5. The light curves and hardness ratio for the 10 ks XMM-Newton exposure.
Fig 3. Relativistic disk lines in the soft X-ray spectrum of MCG The best fit lines have equivalent widths of 20 eV (O VIII), 20 eV (N VII) and 12 eV (C IV). The plot shows the RGS data (blue) , MOS data (red), Laor line model (pink) and powerlaw model (green).