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 ~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.

DI SALVO T, GOLDONI P, STELLA L, VAN DER KLIS M, BAZZANO A, BURDERI L, et al. (2006). A Hard X-Ray View of Scorpius X-1 with INTEGRAL: Nonthermal Emission?. THE ASTROPHYSICAL JOURNAL, 649(2), 91-94 [10.1086/508489].

A Hard X-Ray View of Scorpius X-1 with INTEGRAL: Nonthermal Emission?

DI SALVO, Tiziana;ROBBA, Natale;
2006-01-01

Abstract

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 ~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.
2006
DI SALVO T, GOLDONI P, STELLA L, VAN DER KLIS M, BAZZANO A, BURDERI L, et al. (2006). A Hard X-Ray View of Scorpius X-1 with INTEGRAL: Nonthermal Emission?. THE ASTROPHYSICAL JOURNAL, 649(2), 91-94 [10.1086/508489].
File in questo prodotto:
File Dimensione Formato  
Di_Salvo_2006_ApJ_649_L91.pdf

accesso aperto

Dimensione 420.4 kB
Formato Adobe PDF
420.4 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/32236
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 34
  • ???jsp.display-item.citation.isi??? 34
social impact