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تسجيل مستخدم جديدThe geometry of the quadruply imaged quasar PG 1115+080; implications for Ho
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F. Courbin
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Time delay measurements have recently been reported for the lensed quasar PG 1115+080. These measurements can be used to derive Ho, but only if we can constrain the lensing potential. We have applied a recently developed deconvolution technique to analyse sub-arcsecond I band images of PG 1115+080, obtained at the Nordic Optical Telescope (NOT) and the Canada France Hawaii Telescope (CFHT). The high performance of the deconvolution code allows us to derive precise positions and magnitudes for the four lensed images of the quasar, as well as for the lensing galaxy. The new measurement of the galaxy position improves its precision by a factor of 3 and thus strengthens the constraints on the lensing potential. With the new data, a range of models incorporating some of the plausible systematic uncertainties yields Ho = 53 (+10/-7) km/s/mpc.
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We present time-delay estimates for the quadruply imaged quasar PG 1115+080. Our resuls are based on almost daily observations for seven months at the ESO MPIA 2.2m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per
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We analyzed the microlensing of the X-ray and optical emission of the lensed quasar PG 1115+080. We find that the effective radius of the X-ray emission is 1.3(+1.1 -0.5) dex smaller than that of the optical emission. Viewed as a thin disk observed a
t inclination angle i, the optical accretion disk has a scale length, defined by the point where the disk temperature matches the rest frame energy of the monitoring band (kT=hc/lambda_rest with lambda_rest=0.3 micron), of log[(r_{s,opt}/cm)(cos(i) / 0.5)^{1/2}] = 16.6 pm 0.4. The X-ray emission region (1.4-21.8 keV in the rest frame) has an effective half-light radius of log[r_{1/2,X}/cm] = 15.6 (+0.6-0.9}. Given an estimated black hole mass of 1.2 * 10^9 M_sun, corresponding to a gravitational radius of log[r_g/cm] = 14.3, the X-ray emission is generated near the inner edge of the disk while the optical emission comes from scales slightly larger than those expected for an Eddington-limited thin disk. We find a weak trend supporting models with low stellar mass fractions near the lensed images, in mild contradiction to inferences from the stellar velocity dispersion and the time delays.
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