First 230 GHz VLBI Fringes on 3C 279 using the APEX Telescope

We report about a 230 GHz very long baseline interferometry (VLBI) fringe finder observation of blazar 3C 279 with the APEX telescope in Chile, the phased submillimeter array (SMA), and the SMT of the Arizona Radio Observatory (ARO). We installed VLBI equipment and measured the APEX station position to 1 cm accuracy (1 sigma). We then observed 3C 279 on 2012 May 7 in a 5 hour 230 GHz VLBI track with baseline lengths of 2800 M$\lambda$ to 7200 M$\lambda$ and a finest fringe spacing of 28.6 micro-arcseconds. Fringes were detected on all baselines with SNRs of 12 to 55 in 420 s. The correlated flux density on the longest baseline was ~0.3 Jy/beam, out of a total flux density of 19.8 Jy. Visibility data suggest an emission region <38 uas in size, and at least two components, possibly polarized. We find a lower limit of the brightness temperature of the inner jet region of about 10^10 K. Lastly, we find an upper limit of 20% on the linear polarization fraction at a fringe spacing of ~38 uas. With APEX the angular resolution of 230 GHz VLBI improves to 28.6 uas. This allows one to resolve the last-photon ring around the Galactic Center black hole event horizon, expected to be 40 uas in diameter, and probe radio jet launching at unprecedented resolution, down to a few gravitational radii in galaxies like M 87. To probe the structure in the inner parsecs of 3C 279 in detail, follow-up observations with APEX and five other mm-VLBI stations have been conducted (March 2013) and are being analyzed.Comment: accepted for publication in A&

The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering

The high brightness temperatures, Tb 1013 K, detected in several active galactic nuclei byRadioAstron space VLBI observations challenge theoretical limits. Refractive scattering bythe interstellar medium may affect such measurements. We quantify the scattering propertiesand the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstroncorrelated flux density measurements at 1.7, 4.8, and 22 GHz on projected baselines up to240 000 km we find two characteristic angular scales in the quasar core, about 100 and 10 μas.Some indications of scattering substructure are found. Very high brightness temperatures, Tb≥ 1013 K, are estimated at 4.8 and 22 GHz even taking into account the refractive scattering.Our findings suggest a clear dominance of the particle energy density over the magnetic fieldenergy density in the core of this quasar.Key words: scattering – galaxies: jets – quasars: general – quasars: individual (B0529+483) –radio continuum: galaxies.</p

Introduzione al chip set lh9124 e LH9320 e proposta di applicazione ad una scheda multi-disp per analisi on-line di segnali radioastronomici

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Nuovo spettrometro digitale ad alta risoluzione temporale e frequenziale per applicazioni radioastronomiche

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Humidity reduction for recording headstack used in Noto VLBA terminal

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Un mini correlatore per PC a 16 lags reali

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal