RESUMO
We have detected the four 18 cm OH lines from the z approximaetely 0.765 gravitational lens toward PMN J0134-0931. The 1612 and 1720 MHz lines are in conjugate absorption and emission, providing a laboratory to test the evolution of fundamental constants over a large lookback time. We compare the HI and OH main line absorption redshifts of the different components in the z approximately 0.765 absorber and the z approximately 0.685 lens toward B0218 + 357 to place stringent constraints on changes in F triple-bond g(p)[alpha(2)/mu](1.57). We obtain [DeltaF/F] = (0.44 +/- 0.36(stat) +/- 1.0(sys)t) x 10(-5), consistent with no evolution over the redshift range 0 < z < or = 0.7. The measurements have a 2sigma sensitivity of [Deltaalpha/alpha] < 6.7 x 10(-6) or [Deltamu/mu] < 1.4 x 10(-5) to fractional changes in alpha and mu over a period of approximately 6.5 G yr, half the age of the Universe. These are among the most sensitive constraints on changes in mu.
RESUMO
High angular resolution images of extragalactic radio sources are being made with the Highly Advanced Laboratory for Communications and Astronomy (HALCA) satellite and ground-based radio telescopes as part of the Very Long Baseline Interferometry (VLBI) Space Observatory Programme (VSOP). VSOP observations at 1.6 and 5 gigahertz of the milli-arc-second-scale structure of radio quasars enable the quasar core size and the corresponding brightness temperature to be determined, and they enable the motions of jet components that are close to the core to be studied. Here, VSOP images of the gamma-ray source 1156+295, the quasar 1548+056, the ultraluminous quasar 0014+813, and the superluminal quasar 0212+735 are presented and discussed.
RESUMO
ELLIPTICAL galaxies acting as gravitational lenses occasionally produce spectacular images-Einstein rings-of distant objects. Giant arcs(1) and radio rings(2) have been observed. A wide variety of image morphologies is possible, the generation of which is qualitatively understood in terms of large magnifications at caustic and critical lines in the lensing geometry(3-5). From the angular size of the image, and with knowledge of the distances of the lensed and lensing object, rough estimates of the mass of the lensing galaxy can be obtained. We have made high-resolution radio-interferometric observations of MG1654 + 1346 (ref. 6) a radio quasar in near-perfect alignment with an elliptical galaxy, and show that radio emission is distorted into a narrow Einstein ring that lies within a diamond-shaped region bounded by caustic lines. From the details of the ring structure, a new model for the lensing geometry is deduced which leads to a more accurate estimate of the mass of the lensing galaxy.