The emission regions in X-ray binaries: dipping as a diagnostic

Abstract

X-ray dipping in the black hole binary Cygnus X-1, the Galactic jet source GRO J1655-40 and in low mass X-ray binaries is discussed. It is shown that spectral analysis strongly constrains emission models. Measurement of dip ingress/egress times allows the sizes of extended emission regions to be determined, notably for the Accretion Disk Corona which is responsible for Comptonization in X-ray binaries. In LMXB, the radius of the ADC is shown to be between ~ 10^9 and ~ 5x10^10 cm, an appreciable fraction of the accretion disk radius. This is inconsistent with Comptonization models requiring a localized Comptonizing region, for example, in the immediate neighbourhood of the neutron star. Results from a survey of LMXB using ASCA and BeppoSAX reveal an approximate equality between the height of the blackbody emission region on the neutron star and the height of the inner radiatively-supported disk, suggesting either that there is a direct causal link, such as a radial accretion flow between the inner disk edge and the star, or an indirect link, as in the case of accretion flow creep on the surface of the neutron star as suggested by Inogamov & Sunyaev. Finally, the survey shows that the blackbody cannot originate on the accretion disk as the required inner radii in many sources are substantially less than the neutron star radius.

solicited review paper presented at COSPAR 2000 "X-ray and Gamma-ray Signatures of Black Holes and Weakly Magnetized Neutron Stars"; accepted for publication in Advances in Space Research (2nd affiliation added)

References in corpus (2)

• Results of a LMXB survey: variation in the height of the neutron star blackbody emission region
• Spectral Evolution of the Continuum and Disc Line in Dipping in GRO J1655-40

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• Chandra and RXTE Spectra of the Burster GS 1826-238
• XMM-Newton and optical follow-up observations of SDSS J093249.57+472523.0 and SDSS J102347.67+003841.2
• Discovery of absorption features of the ADC and systematic acceleration of the X-ray burst rate in XB 1323-619
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• Evolution of cross-correlation and time lag of Cyg X-2 along the branches
• Evidence for Quasi-periodic X-Ray Dips from an Ultraluminous X-Ray Source: Implications for the Binary Motion
• A comparison of neutron star blackbody luminosities in LMXB with the theory of accretion flow spreading on the stellar surface
• In-depth studies of the NGC 253 ULXs with XMM-Newton: remarkable variability in ULX1, and evidence for extended coronae
• Reinstating the M31 X-ray system RX J0042.3+4115 as a black hole X-ray binary, and compelling evidence for an extended corona
• Broad-band spectral analysis of LMXB 2S 0921-63 with Suzaku
• Rms-flux relation of Cyg X-1 with RXTE: dipping and nondipping cases