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

Citation:

J. Wagner, A. L. Roy, T. P. Krichbaum, W. Alef, A. Bansod, A. Bertarini, R. Güsten, D. Graham, J. Hodgson, R. Märtens, K. Menten, D. Muders, H. Rottmann, G. Tuccari, A. Weiss, G. Wieching, M. Wunderlich, J. A. Zensus, J. P. Araneda, O. Arriagada, M. Cantzler, C. Duran, F. M. Montenegro-Montes, R. Olivares, P. Caro, P. Bergman, J. Conway, R. Haas, J. Johansson, M. Lindqvist, H. Olofsson, M. Pantaleev, S. Buttaccio, R. Cappallo, G. Crew, S. Doeleman, V. Fish, R.-S. Lu, C. Ruszczyk, J. SooHoo, M. Titus, R. Freund, D. Marrone, P. Strittmatter, L. Ziurys, R. Blundell, R. Primiani, J. Weintroub, K. Young, M. Bremer, S. Sánchez, A. P. Marscher, R. Chilson, K. Asada, and M. Inoue. 2015. “First 230 GHz VLBI fringes on 3C 279 using the APEX Telescope.” Astronomy and Astrophysics, 581.

Abstract:


Aims: We report about a 230 GHz very long baseline interferometry(VLBI) fringe finder observation of blazar 3C 279 with the APEXtelescope in Chile, the phased submillimeter array (SMA), and the SMT ofthe Arizona Radio Observatory (ARO).
Methods: We installed VLBIequipment and measured the APEX station position to 1 cm accuracy(1σ). We then observed 3C 279 on 2012 May 7 in a 5 h 230 GHz VLBItrack with baseline lengths of 2800 Mλ to 7200 Mλ and afinest fringe spacing of 28.6 μas.
Results: Fringes weredetected on all baselines with signal-to-noise ratios of 12 to 55 in 420s. The correlated flux density on the longest baseline was ~0.3 Jybeam-1, out of a total flux density of 19.8 Jy. Visibilitydata suggest an emission region ≲ 38 μas in size, and at leasttwo components, possibly polarized. We find a lower limit of thebrightness temperature of the inner jet region of about 1010