Cookies

We use cookies to ensure that we give you the best experience on our website. You can change your cookie settings at any time. Otherwise, we'll assume you're OK to continue.

Durham University

Department of Physics

Staff profile

Publication details for Prof Chris Done

Sobolewska, M. A. & Done, C. (2007). What is the origin of the soft excess in active galactic nuclei? Monthly Notices of the Royal Astronomical Society 374(1): 150-158.

Author(s) from Durham

Abstract

We investigate the nature of the soft excess below 1 keV observed in active galactic nuclei. We use the XMM–Newton data of the low-redshift, optically bright quasar, PG 1211+143, and we compare it with the narrow-line Seyfert 1 galaxy, 1H 0707−495, which has one of the strongest soft excesses seen. We test various ideas for the origin of the soft X-ray excess, including a separate spectral component (for example, low-temperature Comptonized emission), a reflection-dominated model, or a complex absorption model. All three can give good fits to the data, and χ2-fitting criteria are not sufficient to discriminate among them. Instead, we favour the complex absorption model on the grounds that it requires less extreme parameters. In particular, the geometry appears to be more physically plausible as the reflected component in the smeared absorption model is no longer dominant, and relativistic distortions, while still clearly present, are not tremendously larger than expected for a disc around a Schwarzchild black hole.

References

Ballantyne D. R., Iwasawa K., Fabian A. C., 2001, MNRAS, 323, 506
Bautista M. A., Kallman T. R., 2001, ApJS, 134, 139
Blustin A. J., Page M. J., Fuerst S. V., Branduardi-Raymont G., Ashton C.
E., 2005, A&A, 431, 111
Boller T. et al., 2002, MNRAS, 329, L1.
Boller T., Tanaka Y., Fabian A., Brandt W. N., Gallo L., Anabuki N., Haba
Y., Vaughan S., 2003, MNRAS, 343, L89
Boroson T. A., 2002, ApJ, 565, 78
Chevallier L., Collin S., Dumont A.-M., Czerny B., Mouchet M., Gon¸calves
A. C., Goosmann R., 2006, A&A, 449, 493
Crummy J., Fabian A. C., Gallo L., Ross R. R., 2006, MNRAS, 365,
1067
Czerny B., Nikolajuk M., R´o˙za´nska A., Dumont A.-M., Loska Z., ˙ Zycki P.
T., 2003, A&A, 412, 317
Done C., Sobolewska M., Gierli´nski M., Schurch N. 2006, MNRAS, in press
Fabian A. C., Ballantyne D. R., Merloni A., Vaughan S., Iwasawa K., Boller
T., 2002, MNRAS, 331, L35
Fabian A. C., Miniutti G., Gallo L., Boller T., Tanaka Y., Vaughan S., Ross
R. R., 2004, MNRAS, 353, 1071
Fabian A. C., Miniutti G., Iwasawa K., Ross R. R., 2005, MNRAS, 361,
795
Gallo L. C., 2006, MNRAS, 368, 479
Gallo L. C., Boller T., Tanaka Y., Fabian A. C., Brandt W. N., Welsh W. F.,
Anabuki N., Haba Y., 2004, MNRAS, 347, 269
Gierli´nski M., Done C., 2004, MNRAS, 349, L7 (GD04)
Gierli´nski M., Done C., 2006, MNRAS, 371, L16
Green P. J., 2006, ApJ, 644, 733
Janiuk A., Czerny B., Madejski G. M., 2001, ApJ, 557, 408
Kubota A., Done C., 2004, MNRAS, 353, 980
Kubota A., Makishima K., Ebisawa K., 2001, ApJL, 560, L147
Laor A., 1991, ApJ, 376, 90
Laor A., Netzer H., 1989, MNRAS, 238, 897
Leighly K. M., 2004, ApJ, 611, 125
Merloni A., 2003, MNRAS, 341, 1051
Miniutti G., Fabian A. C., 2004, MNRAS, 349, 1435
Murashima M., Kubota A., Makishima K., Kokubun M., Hong S., Negoro
H., 2005, PASJ, 57, 279
Nayakshin S., Kazanas D., Kallman T., 1999, Bull. Am. Astron. Soc., 31,
1426
Page K. L., Reeves J. N., O’Brien P. T., Turner M. J. L., Worrall D. M.,
2004a, MNRAS, 353, 133
Page K. L., Turner M. J. L., Done C., O’Brien P. T., Reeves J. N., Sembay
S., Stuhlinger M., 2004b, MNRAS, 349, 57
Ponti G., Cappi M., Dadina M., Malaguti G., 2004, A&A, 417, 451
Ponti G., Miniutti G., Cappi M., Maraschi L., Fabian A. C., Iwasawa K.,
2006, MNRAS, 368, 903
Porquet D., Reeves J. N., O’Brien P., Brinkmann W., 2004, A&A, 422, 85
Proga D., Stone J. M., Kallman T. R., 2000, ApJ, 543, 686
Reeves J. N., Porquet D., Turner T. J., 2004, ApJ, 615, 150
Remillard R. A., McClintock J. E., 2006, ARA&A, 44, 49
Fabian A. C., 2005, MNRAS, 358, 211
Ross R. R., Fabian A. C., 1993, MNRAS, 261, 74
Schurch N. J., Done C., 2006, MNRAS, 371, 81
Shakura N. I., Sunyaev R. A., 1973, A&A, 24, 337
Tanaka Y., Boller T., Gallo L., 2005, in Merloni A., Nayakshin S., Sunyaev
R. A., eds, ESO Astrophysics Symp., Growing Black Holes: Accretion
in a Cosmological Context. Springer, Berline, p. 290
Tanaka Y., Boller T., Gallo L., Keil R., Ueda Y., 2004, PASJ, 56, L9
Titarchuk L., 1994, ApJ, 434, 570
Turner T. J., Pounds K. A., 1988, MNRAS, 232, 463
Zheng W. et al., 2001, ApJ, 562, 152
˙ Zycki P. T., Done C., Smith D. A., 1999, MNRAS, 309, 561.