RESOLVING THE INNER JET STRUCTURE OF 1924-292 WITH THE EVENT HORIZON TELESCOPE

• Published in: Astrophysical journal. Letters 2012-09, Vol.757 (1), p.1-5, Article L14
• Main Authors: Lu, Ru-Sen, Fish, Vincent L, WEINTROUB, JONATHAN, DOELEMAN, SHEPERD S, Bower, Geoffrey C, Freund, Robert, Friberg, Per, Ho, Paul T P, HONMA, MAREKI, Inoue, Makoto
• Format: Article
• Language: English
• Subjects: Active galactic nuclei; Arrays; Astronomy; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BRIGHTNESS; Brightness temperature; Closures; Event horizon; GALAXIES; GHZ RANGE; INTERFEROMETRY; JET MODEL; QUASARS; RESOLUTION; TELESCOPES
• ISSN: 0004-637X; 2041-8205; 1538-4357; 2041-8213
• DOI: 10.1088/2041-8205/757/1/L14

We present the first 1.3 mm (230 GHz) very long baseline interferometry model image of an active galactic nucleus (AGN) jet using closure phase techniques with a four-element array. The model image of the quasar 1924-292 was obtained with four telescopes at three observatories: the James Clerk Maxwell Telescope on Mauna Kea in Hawaii, the Arizona Radio Observatory's Submillimeter Telescope in Arizona, and two telescopes of the Combined Array for Research in Millimeter-wave Astronomy in California in 2009 April. With the greatly improved resolution compared with previous observations and robust closure phase measurement, the inner jet structure of 1924-292 was spatially resolved. The inner jet extends to the northwest along a position angle of -53[degrees] at a distance of 0.38 mas from the tentatively identified core, in agreement with the inner jet structure inferred from lower frequencies, and making a position angle difference of ~80[degrees] with respect to the centimeter jet. The size of the compact core is 0.15 pc with a brightness temperature of 1.2 x 10 super(11) K. Compared with those measured at lower frequencies, the low brightness temperature may argue in favor of the decelerating jet model or particle-cascade models. The successful measurement of closure phase paves the way for imaging and time resolving Sgr A* and nearby AGNs with the Event Horizon Telescope.