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