A deep Chandra ACIS study of NGC 4151. III. the line emission and spectral analysis of the ionization cone

Junfeng Wang, Giuseppina Fabbiano, Martin Elvis, Guido Risaliti, Margarita Karovska, Andreas Zezas, Carole G. Mundell, Gaelle Dumas, Eva Schinnerer

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59 Citations (SciVal)


This paper is the third in a series in which we present deep Chandra ACIS-S imaging spectroscopy of the Seyfert1 galaxy NGC 4151, devoted to study its complex circumnuclear X-ray emission. Emission features in the soft X-ray spectrum of the bright extended emission (L 0.3-2 keV ∼ 10 40 erg s-1) at r > 130pc (2″) are consistent with blended brighter O VII, O VIII, and Ne IX lines seen in the Chandra HETGS and XMM-Newton RGS spectra below 2keV. We construct emission line images of these features and find good morphological correlations with the narrow-line region clouds mapped in [O III] λ5007. Self-consistent photoionization models provide good descriptions of the spectra of the large-scale emission, as well as resolved structures, supporting the dominant role of nuclear photoionization, although displacement of optical and X-ray features implies a more complex medium. Collisionally ionized emission is estimated to be ≲12% of the extended emission. Presence of both low- and high-ionization spectral components and extended emission in the X-ray image perpendicular to the bicone indicates leakage of nuclear ionization, likely filtered through warm absorbers, instead of being blocked by a continuous obscuring torus. The ratios of [O III]/soft X-ray flux are approximately constant (∼15) for the 1.5kpc radius spanned by these measurements, indicating similar relative contributions from the low- and high-ionization gas phases at different radial distances from the nucleus. If the [O III] and X-ray emission arise from a single photoionized medium, this further implies an outflow with a wind-like density profile. Using spatially resolved X-ray features, we estimate that the mass outflow rate in NGC 4151 is ∼2 M yr-1 at 130pc and the kinematic power of the ionized outflow is 1.7 × 1041 erg s-1, approximately 0.3% of the bolometric luminosity of the active nucleus in NGC 4151.

Original languageEnglish
Article number23
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 2 Nov 2011


  • galaxies: individual (NGC 4151)
  • galaxies: ISM
  • galaxies: Seyfert
  • ISM: jets and outflows
  • X-rays: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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