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Durham University

Department of Physics

Staff profile

Publication details for Prof Chris Done

Di Salvo, T., Done, C. , Życki, P. T. Burderi, L. & Robba, N. R. (2001). Probing the inner region of Cygnus X-1 in the low/hard state through its x-ray broadband spectrum. Astrophysical Journal 547(2): 1024-1033.

Author(s) from Durham

Abstract

We present the broadband X-ray spectrum of Cyg X-1 in the low/hard state as observed by the instruments on board BeppoSAX. The spectrum spans from 0.1 to 200 keV, allowing the total accretion luminosity to be observed rather than extrapolated, corresponding to 2% of the Eddington limit for a 10 M black hole. The broad bandpass allows us to determine the continuum shape with great accuracy. Simple models of Compton upscattering of seed photons from the accretion disk do not adequately match the spectrum. At low energies an additional continuum component is required, giving a complex soft excess which extends up to 4 keV, in line with previous results from ASCA. Moreover, we clearly detect a reflected component from the accretion disk that is smeared, probably because of relativistic and Doppler effects. The reflecting material is not strongly ionized and does not subtend a large solid angle as seen from the corona (/20.10.3). The estimated inner radius of the disk, which depends on the inclination of the system, is most probably between 10 and 70 gravitational radii (Rg). An unsmeared reprocessed component, probably originating from the companion star or the outer disk, could also be present. In this case, the inner radius of the disk, as inferred from the smeared reflection, is smaller, between 6Rg and 20Rg.

References

Aharonian, F. A., & Atoyan, A. M. 1995, Astropart. Phys., 3, 275
Arnaud, K. A. 1996, in ASP Conf. Ser. 101, Astronomical Data Analysis
Software and Systems V, ed. G. H. Jacoby & J. Barnes (San Francisco:
ASP), 17
Beloborodov, A. M. 1999a, ApJ, 510, L123
ÈÈÈ. 1999b, in ASP Conf. Ser. 161, High Energy Processes in Accreting
Black Holes, ed. J. Poutanen & R. Svensson (San Francisco: ASP), 295
Boella, G., et al. 1997, A&AS, 122, 327
Chiang, J., Reynolds, C. S., Blaes, O. M., Nowak, M. A., Murray, N.,
Madejski, G., Marshall, H. L., & Magdziarz, P. 2000, ApJ, 528, 292
Coppi, P. S. 1999, in ASP Conf. Ser. 161, High Energy Processes in Accreting
Black Holes, ed. J. Poutanen & R. Svensson (San Francisco: ASP),
375
Di Matteo, T., & Psaltis, D. 1999, ApJ, 526, L101
Done, C., Madejski, G. M., & Z0 ycki, P. T. 2000, ApJ, 536, 213
Done, C., Mulchaey, J. S., Mushotzky, R. F., & Arnaud, K. A. 1992, ApJ,
395, 275
Done, C., & Z0 ycki, P. T. 1999, MNRAS, 305, 457
Dove, J. B., Wilms, J., Maisack, M., & Begelman, M. C. 1997, ApJ, 487, 759
Ebisawa, K., et al. 1996, ApJ, 467, 419
Fabian, A. C., Rees, M. J., Stella, L., & White, N. E. 1989, MNRAS, 238,
729
Frank, J., King, A., & Raine, D. 1992, Accretion Power in Astrophysics
(Cambridge Astrophysics Ser. 21; Cambridge: Cambridge Univ. Press)
Frontera, F., et al. 1997, A&AS, 122, 357
Galeev, A. A., Rosner, R., & Vaiana, G. S. 1979, ApJ, 229, 318
George, I. M., & Fabian, A. C. 1991, MNRAS, 249, 352
Gierlin ski, M., Zdziarski, A. A., Done, C., Johnson, W. N., Ebisawa, K.,
Ueda, Y., Haardt, F., & Phlips, B. F. 1997, MNRAS, 288, 958
Gierlin ski, M., Zdziarski, A. A., Poutanen, J., Coppi, P. S., Ebisawa, K., &
Johnson, W. N. 1999, MNRAS, 309, 496
Gies, D. R., & Bolton, C. T. 1982, ApJ, 260, 240
ÈÈÈ. 1986, ApJ, 304, 371
Gilfanov, M., Churazov, E., & Revnivtsev, M. 1999, A&A, 352, 182
Haardt, F., & Maraschi, L. 1993, ApJ, 413, 507
Haardt, F., Maraschi, L., & Ghisellini, G. 1994, ApJ, 432, L95
Herrero, A., Kudritzki, R. P., Gabler, R., Vilchez, J. M., & Gabler, A. 1995,
A&A, 297, 556
Ichimaru, S. 1977, ApJ, 214, 840
Iwasawa, K., et al. 1996, MNRAS, 282, 1038
Lee, J. C., Fabian, A. C., Brandt, W. N., Reynolds, C. S., & Iwasawa,
K. 1999, MNRAS, 310, 973
Lightman, A. P., & White, T. R. 1988, ApJ, 335, 57
Magdziarz, P., Blaes, O. M., Zdziarski, A. A., Johnson, W. N., & Smith,
D. A. 1998, MNRAS, 301, 179
Magdziarz, P., & Zdziarski, A. A. 1995, MNRAS, 273, 837
Malysheva, L. K. 1997, Astron. Lett., 23, 585
Manzo, G., Giarrusso, S., Santangelo, A., Ciralli, F., Fazio, G., Piraino, S.,
& Segreto, A. 1997, A&AS, 122, 341
Massaro, E., Cusumano, G., Litterio, M., & Mineo, T. 2000, A&A, 361, 695
Massey, P., Johnson, K. E., & Degioia-Eastwood, K. 1995, ApJ, 454, 151
Matt, G., Perola, G. C., & Piro, L. 1991, A&A, 247, 25
Miller, K. A., & Stone, J. M. 2000, ApJ, 534, 398
Mitsuda, K., et al. 1984, PASJ, 36, 741
Morrison, R., & McCammon, D. 1983, ApJ, 270, 119
Narayan, R. 1996, in IAU Colloq. 163, Accretion Phenomena and Related
OutÑows, ed. D. T. Wickramasinghe, G. Bicknell, & L. Ferrario (ASP
Conf. Ser. 121; San Francisco: ASP), 75
Narayan, R., & Yi, I. 1995, ApJ, 452, 710
Nayakshin, S. 2000, ApJ, 534, 718
Nayakshin, S., Kazanas, D., & Kallman, T. R. 2000, ApJ, 537, 833
Ninkov, Z., Walker, G. A. H., & Yang, S. 1987, ApJ, 321, 425
Parmar, A. N., et al. 1997, A&AS, 122, 309
Poutanen, J. 1998, in Theory of Black Hole Accretion Disks, ed. M. A.
Abramowicz, G. Bjornsson, & J. E. Pringle (Cambridge: Cambridge
Univ. Press), 100
Poutanen, J., Krolik, J. H., & Ryde, F. 1997, MNRAS, 292, L21
Ross, R. R., & Fabian, A. C. 1993, MNRAS, 261, 74
Ross, R. R., Fabian, A. C., & Young, A. J. 1999, MNRAS, 306, 461
Ro z5 an ska, A., & Czerny, B. 2000, A&A, 360, 1170
Shakura, N. I., & Sunyaev, R. A. 1973, A&A, 24, 337
Shapiro, S. L., Lightman, A. P., & Eardley, D. M. 1976, ApJ, 204, 187
Shimura, T., & Takahara, F. 1995, ApJ, 445, 780
Sowers, J. W., Gies, D. R., Bagnuolo, W. G., Shafter, A. W., Wiemker, R., &
Wiggs, M. S. 1998, ApJ, 506, 424
Stern, B. E., Poutanen, J., Svensson, R., Sikora, M., & Begelman, M. C.
1995, ApJ, 449, L13
Tanaka, Y., et al. 1995, Nature, 375, 659
Titarchuk, L. 1994, ApJ, 434, 570
White, N. E., Stella, L., & Parmar, A. N. 1988, ApJ, 324, 363
Zdziarski, A. A. 1998, MNRAS, 296, L51
Zdziarski, A. A., Johnson, W. N., & Magdziarz, P. 1996, MNRAS, 283, 193
Zdziarski, A. A., Lubin ski, P., & Smith, D. A. 1999, MNRAS, 303, L11
Zhang, S. N., Cui, W., Chen, W., Yao, Y., Zhang, X., Sun, X., Wu, X., &
Xu, H. 2000, Science, 287, 1239
Z0 ycki, P. T., Done, C., & Smith, D. A. 1997, ApJ, 488, L113
ÈÈÈ. 1998, ApJ, 496, L25
ÈÈÈ. 1999, MNRAS, 305, 231
Z0 ycki, P. T., Krolik, J. H., Zdziarski, A. A., & Kallman, T. R. 1994, ApJ,
437, 597.