Universities Space Research Association | Arecibo Observatory | 2017 Jan 04
Remarkable new observations derived by linking Arecibo Observatory's 305-meter dish with the Russian RadioAstron space radio telescope have provided results that are causing much head scratching in radio astronomical circles. What used to be a well-understood explanation of the mechanism that generates intense radio signals from tiny and very distant quasar nuclei has now been tested in previously impossible ways.
The RadioAstron satellite, launched in 2011 by the Russian Federal Space Agency, carries a 10-m radio dish and is traveling around the Earth in a highly elliptical orbit that takes it out to 350,000 km from Earth -- almost the distance to the Moon. When the signals it receives from a distant quasar are combined with simultaneous data acquired by its Earth-based partners at Arecibo in Puerto Rico, Green Bank in West Virginia, Socorro in New Mexico, and Bonn in Germany, the observations simulate a dish up to 350,000 km in diameter. This network of telescopes operates at frequencies (wavelengths) of 330 MHz (92 cm), 1.7 GHz (18 cm), 4.7 GHz (6.2 cm) and 22 GHz (1.3 cm). ...
Combining the signals produces what are called fringes, and it was recently reported that quasar 3C 273 was detected at a baseline of 170,000 km (106,000 miles). This remarkable achievement showed that 3C 273 has structure in its core at least as small as 26 microarcseconds across. At the distance of 3C 273, this corresponds to a physical diameter of 2.7 light-months. The ability to see such detail is not matched by any other telescope in the world. Optical telescopes, even the Hubble Space Telescope, do not come anywhere near this ability to see detailed structure. ...
RadioAstron Observations of the Quasar 3C273: a Challenge to the Brightness Temperature Limit - Y. Y. Kovalev et al
- Astrophysical Journal Letters 820(1):L9 (2016 Mar 20) DOI: 10.3847/2041-8205/820/1/L9
arXiv.org > astro-ph > arXiv:1601.05806 > 21 Jan 2016 (v1), 02 Mar 2016 (v2)