A hard X-ray view of Scorpius X-1 with INTEGRAL:: Nonthermal emission?

被引：36

作者：

Di Salvo, T.

Goldoni, P.

Stella, L.

van der Klis, M.

Bazzano, A.

Burderi, L.

Farinelli, R.

Frontera, F.

Israel, G. L.

Mendez, M.

Mirabel, I. F.

Robba, N. R.

Sizun, P.

Ubertini, P.

Lewin, W. H. G.

机构：

[1] Univ Palermo, Dipartimento Sci Fisiche & Astron, I-90123 Palermo, Italy

[2] APC, UMR 7164, Lab Astropart & Cosmol, F-75231 Paris 05, France

[3] CEA Saclay, DSM, DAPNIA, Serv Astrophys, F-91191 Gif Sur Yvette, France

[4] Osserv Astron Roma, I-00040 Monte Porzio Catone, Italy

[5] Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands

[6] Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands

[7] INAF, Ist Astrofis Spaziale & Fis Cosm, Sez Roma, I-00133 Rome, Italy

[8] Univ Cagliari, Dipartimento Fis, I-09042 Monserrato, Italy

[9] Univ Ferrara, Dipartimento Fis, I-44100 Ferrara, Italy

[10] SRON, Netherlands Inst Space Res, NL-3584 CA Utrecht, Netherlands

[11] European So Observ, Santiago 19001, Chile

[12] MIT, Ctr Space Res, Cambridge, MA 02139 USA

来源：

ASTROPHYSICAL JOURNAL | 2006年 / 649卷 / 02期

关键词：

accretion; accretion disks; stars : individual (Scorpius X-1); stars : neutron; X-rays : binaries; X-rays : general; X-rays : stars;

D O I：

10.1086/508489

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present here simultaneous INTEGRAL/RXTE observations of Sco X-1 and in particular a study of the hard X-ray emission of the source and its correlation with the position in the Z track of the X-ray color-color diagram. We find that the hard X-ray ( above about 30 keV) emission of Sco X-1 is dominated by a power-law component with a photon index of similar to 3. The flux in the power-law component slightly decreases when the source moves in the color-color diagram in the sense of increasing inferred mass accretion rate from the horizontal branch to the normal branch/flaring branch vertex. It becomes not significantly detectable in the flaring branch, where its flux has decreased by about an order of magnitude. These results present close analogies to the behavior of GX 17 + 2, one of the so-called Sco-like Z sources. Finally, the hard power law in the spectrum of Sco X-1 does not show any evidence of a high-energy cutoff up to 100 - 200 keV, strongly suggesting a nonthermal origin of this component.

引用

页码：L91 / L94

页数：4

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