RadioAstron -- a Telescope with a Size of 300 000 km: Main Parameters and First Observational Results

Abstract

The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna ground-space radio interferometer with extremely long baselines, making it possible for the first time to study various objects in the Universe with angular resolutions a million times better than is possible with the human eye. The project is targeted at systematic studies of compact radio-emitting sources and their dynamics. Objects to be studied include supermassive black holes, accretion disks, and relativistic jets in active galactic nuclei, stellar-mass black holes, neutron stars and hypothetical quark stars, regions of formation of stars and planetary systems in our and other galaxies, interplanetary and interstellar plasma, and the gravitational field of the Earth. The results of ground-based and inflight tests of the space radio telescope carried out in both autonomous and ground-space interferometric regimes are reported. The derived characteristics are in agreement with the main requirements of the project. The astrophysical science program has begun.

The Nuclear Structure of 3C84 with Space VLBI (RadioAstron) Observations

“…3C 84 was observed with the 10-m Space Radio Telescope (SRT) of the RadioAstron Mission (Kardashev et al 2012;2013) at 5 and 22 GHz as a part of the RadioAstron Nearby AGN Key Science Program (Savolainen et al, these proceedings). Observations were carried out on September 21, 2013, outside of the regular EVN sessions because of the SRT constrains.…”

“…Two γ-ray flaring periods have been reported: the first one in April-May 2009(Kataoka et al 2010) and the second one in June-August 2010 (Brown & Adams 2011). During both of the γ-ray flares, components C1 and C3 showed a large change of the flux density, but on a time scale longer than that of the γ-ray activity.…”

Black hole superradiance and polarization-dependent bending of light

“…Contours of constant angle |∆φ + −∆φ − | are shown with dot-dashed diagonal black lines, and the shaded area in magenta corresponds to 10 −4 M S /M 10 −1 . We fix E γ = 1 GHz, and -to give an idea about the relevance of the effect -we quote the angular resolution of the Spektr-R radio telescope [52][53][54], δθ Eγ =1 GHz Spektr−R 2 × 10 −4 arcsec. We postpone to section 4 a more detailed discussion about experimental prospects.…”

“…A further improvement can be obtained by combining a VLBI array with an additional antenna placed on board of a satellite orbiting the Earth. As a benchmark reference, let us consider the case of the Russian project Spektr-R [52][53][54]. Spektr-R (formerly RadioAstron) is a dual-polarization receiver space-based 10 meter radio telescope in a highly apogee orbit around the Earth, launched on July 2011.…”

“…Spektr-R (formerly RadioAstron) is a dual-polarization receiver space-based 10 meter radio telescope in a highly apogee orbit around the Earth, launched on July 2011. Spektr-R works in conjunction with some of the largest ground-based radio telescopes, and the system forms an interferometric baseline extending up to 3 × 10 5 km [52][53][54]. This configuration is able to reach an astonishing angular resolution up to a few millionths of an arcsecond.…”