Abstract of the proposal for the experiment EM143A |
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The gravitational lens in PKS1830-211 is a rather unique object: the background AGN is a strong gamma emitter and its images pass across a rich forest of molecular-absorption lines from the lensing galaxy, located at a redshift of about 0.9. This source has been, indeed, a key for precise cosmological tests (from measurement of the CMB temperature in the cosmic past to constrains in the evolution of Fundamental Constants of Physics). Hence, understanding the geometry and evolution of this system is of particular importance. We propose EVN observations at C and X bands, using an in-beam phase-referencing strategy, to 1) check the precession jet model of the AGN (which is based on data from two decades ago), 2) study the chromatic structure of the jet and its polarization and 3) detect the third image of the lens system, which will allow us to further constrain the geometry of the lensing model. |