New X-ray Spectral Data of NGC 4151 observed with Asuka

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Session 59 -- Low Luminosity AGNs and Active Galaxies
Display presentation, Thursday, 2, 1994, 9:20-6:30

[59.10] New X-ray Spectral Data of NGC 4151 observed with Asuka

K.A.Weaver (Penn State), S.S.Holt, T.Yaqoob (NASA/GSFC), and the Asuka Team

We present new X-ray spectral data for the well-studied Seyfert 1 galaxy NGC 4151. This source was observed for 20 ksecs twice during the Asuka PV phase, once on 25 May 1993 and again on 5 November 1993. NGC 4151 underwent strong flux and spectral variability between the two observations; it's flux increased by a factor of three while there was an apparent column density decrease from 8 to 3 $\times$ 10$^{22}$ cm$^{-2}$. At energies of less than 1 keV, the data from the Asuka Solid-state Imaging Spectrometer (SIS) have a much higher S/N than the spectra that were obtained with the Broad Band X-Ray Telescope (BBXRT). We find that the known soft X-ray excess in NGC 4151 is more complicated than previously thought. In addition to the scattered (a.k.a. ``partial covering'') soft excess component, we have detected an ``ultrasoft'' soft excess component that can be described by a 0.2 keV thermal bremsstrahlung spectrum. There is also evidence for line emission between 0.6 and 0.9 keV. We will discuss how the ultrasoft excess may relate to the extended soft X-ray emission seen by the Einstein Observatory HRI and the Rosat HRI.

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