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Astron. Astrophys. 339, 337-344 (1998)

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Evidence for ionized reprocessing in the X-ray spectrum of the Seyfert 1 Galaxy 1E 1615+061

M. Guainazzi 1, 2, L. Piro 3, M. Capalbi 2, A.N. Parmar 1, M. Yamauchi 4 and M. Matsuoka 5

1 Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
2 Beppo-SAX Science Data Center, c/o Nuova Telespazio, Via Corcolle 19, I-00131 Roma, Italy
3 Istituto di Astrofisica Spaziale, C.N.R., Via Fosso del Cavaliere, I-00133 Roma, Italy
4 X-ray Astronomy Laboratory, Dept. of Electrical and Electronic Engineering, Faculty of Engineering, Miyazaki University, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki, Miyazaki 889-2155, Japan
5 Cosmic Radiation Laboratory, RIKEN, 2-1 Hirosawa, 350-01 Wako-shi, Saitama, Japan

Received 6 April 1998 / Accepted 28 August 1998

Abstract

The Seyfert 1 galaxy 1E 1615+061 was observed to display a very steep ([FORMULA]) and intense soft X-ray spectrum during a HEAO-1 A2 observation in the 1978. Such an exceptionally soft X-ray state has never been observed subsequently, but the source has continued to exhibit a large (up to a factor 6) range of X-ray intensity variability. The overall UV/X-ray spectrum of this source, observed during a multiwavelength campaign in 1991-1992, can be well fit with a self-consistent, low-[FORMULA] accretion disk model. In this model, the soft X-rays result were suggested to arise from reflection of the nuclear emission by mildly ionized ([FORMULA]) material in the inner regions of the disk. In this Paper we report the results of an ASCA observation in 1995 August, which give a direct confirmation of such a scenario. The spectrum may be modeled as a power-law with a photon index of 1.8, together with absorption consistent with the galactic line of sight value, substantial reflection from ionized material and an iron fluorescent [FORMULA] emission line. The centroid energy ([FORMULA]6.6-6.8 keV) implies a ionization stage [FORMULA] FeXIX . The line profile is consistent with that expected from a kinematically and gravitationally distorted line around a black hole. These results provide the first direct evidence for the existence of considerable amount of ionized material around the nucleus of a "broad" Seyfert 1 galaxy.

Key words: X-ray: galaxies – galaxies: Seyfert – galaxies: individual: 1E 1615+061 – accretion, accretion disks

Send offprint requests to: M. Guainazzi, (mguainaz@astro.estec.esa.nl)

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© European Southern Observatory (ESO) 1998

Online publication: October 21, 1998
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