Abstract
FLUORESCENT emission from iron and the detection of a Compton reflection 'hump'1–3 in the X-ray spectra4,5 of many active galaxies are strong evidence for the presence of cold (nearly neutral) optically thick material in their nuclear regions. An apparent absorption edge at 8–9 keV, attributed to iron, in about half of a large number of Seyfert galaxies5 indicates the additional presence of warm (partially ionized) absorbing material, which could modify the emergent X-ray spectrum and explain flux-correlated changes in spectral shape6–8. If this interpretation is correct, the warm absorber should give rise to a number of spectral features, particularly absorption edges, whose energy can be used to deduce the ionization state of the material. Here we report the detection of such a feature in the bright Seyfert galaxy MCG-6-30-15, in the form of absorption at 0.8 keV arising from the presence of highly ionized oxygen. This warm absorber will be difficult to detect at other wavelengths but, may contribute significantly to the overall X-ray opacity of the nuclear region.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Guilbert, P. W. & Rees, M. Mon. Not. R. astr. Soc. 233, 475–484 (1988).
Lightman, A. P. & White, T. R. Astrophys. J. 335, 57–66 (1988).
George, I. M. & Fabian, A. C. Mon. Not. R. astr. Soc. 249, 352–367 (1991).
Pounds, K. A., Nandra, K., Stewart, G. C. George, I. M. & Fabian, A. C. Nature 344, 132–133 (1990).
Nandra, K. Thesis, Leicester Univ. (1991).
Pan, H.-C., Stewart, G. C. & Pounds, K. A. Mon. Not. R. astr. Soc. 242, 177–187 (1990).
Nandra, K. et al. Mon. Not. R. astr. Soc. 248, 760–772 (1991).
Fiore, F., Perola, G. C., Matsuoka, M., Yamauchi, M. & Piro, L. Astr. Astrophys. (in the press).
Pfeffermann, E. et al. Proc. SPIE 733, 519 (1986).
Nandra, K., Pounds, K. A. & Stewart, G. C., Mon. Not. R. astr. Soc. 242, 660–668 (1990).
Matsuoka, M., Yamauchi, M., Piro, L. & Murakami, T. Astropnys. J. 361, 440–458 (1990).
Hasinger, G., Turner, T. J., George, I. M. & Boese, G. OGIP Calibration Memo CAL/ROS/92-001 (NASA/GSFC, Greenbelt, Maryland, 1992).
Burstein, D. & Heiles, C. Astr. J. 87, 1165–1189 (1982).
Bevington, P. R., Data Reduction and Error Analysis for the Physical Sciences (McGraw-Hill, New York, 1969).
Reilman, R. F. & Manson, S. T. Astrophys. J. Suppl. Ser. 40, 815–880 (1979).
Kallman, T. R. & McCray, R. Astrophys. J. Suppl. 50, 263–318 (1982).
Osterbrock, D. E. Astrophysics of gaseous Nebulae. (Freeman, San Francisco, 1979).
Ferland, G. J. Korista, & Peterson, B. M. Astrophys. J. 363, L21–L25 (1990).
Antonucci, R. R. J. & Miller, J. S. Astrophys. J. 297, 621–632 (1985).
Nandra, K. et al. Mon. Not. R. astr. Soc. (in the press).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Nandra, K., Pounds, K. Highly ionized gas in the nucleus of the active galaxy MCG-6-30-15. Nature 359, 215–216 (1992). https://doi.org/10.1038/359215a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/359215a0
This article is cited by
-
X-ray absorption and reflection in active galactic nuclei
The Astronomy and Astrophysics Review (2009)
-
Gravitationally redshifted emission implying an accretion disk and massive black hole in the active galaxy MCG–6–30–15
Nature (1995)
-
The SAX mission for wide-band X-ray astronomy
Il Nuovo Cimento C (1993)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
