Astrophys. J., 633, 228-239 (2005/November-1)
A remarkable low-mass X-ray binary within 0.1 parsecs of the Galactic Center.
MUNO M.P., LU J.R., BAGANOFF F.K., BRANDT W.N., GARMIRE G.P., GHEZ A.M., HORNSTEIN S.D. and MORRIS M.R.
Abstract (from CDS):
Recent X-ray and radio observations by Muno et al. and Bower et al. have identified a transient low-mass X-ray binary (LMXB) located only 0.1 pc in projection from the Galactic center, CXOGC J174540.0-290031. In this paper, we report the detailed analysis of X-ray and infrared observations of the transient and its surroundings. Chandra observations detect the source at a flux of FX=2x10–12 ergs/cm2/s (2-8 keV). After accounting for absorption both in the interstellar medium (ISM) and in material local to the source, the implied luminosity of the source is only LX=4x1034 ergs/s (2-8 keV; D=8 kpc). However, the diffuse X-ray emission near the source also brightened by a factor of 2. The enhanced diffuse X-ray emission lies on top of a known ridge of dust and ionized gas that is visible in infrared images. We interpret the X-ray emission as scattered flux from the outburst and determine that the peak luminosity of CXOGC J174540.0-290031 was LX≳2x1036 ergs/s. We suggest that the relatively small observed flux results from the fact that the system is observed nearly edge-on, so that the accretion disk intercepts most of the flux emitted along our line of sight. We compare the inferred peak X-ray luminosity to that of the radio jet. The ratio of the X-ray to radio luminosities, LX/LR≲104, is considerably smaller than in other known LMXBs (≳105). This is probably because the jets are radiating with unusually high efficiency at the point where they impact the surrounding ISM. This hypothesis is supported by a comparison with mid-infrared images of the surrounding dust. Finally, we find that the minimum power required to produce the jet, Ljet∼1037 ergs/s, is comparable to the inferred peak X-ray luminosity. This is the most direct evidence yet obtained that LMXBs accreting at low rates release about half of their energy as jets.
Accretion, Accretion Disks - Galaxy: Center - X-Rays: Binaries
Parag. 4.2 : X 1822-731 is a misprint for X 1822-371
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