The 1.4 mm Core of Centaurus A: First VLBI Results with the South Pole Telescope

Junhan Kim, Daniel P. Marrone, Alan L. Roy, Jan Wagner, Keiichi Asada, Christopher Beaudoin, Jay Blanchard, John E. Carlstrom, Ming Tang Chen, Thomas M. Crawford, Geoffrey B. Crew, Sheperd S. Doeleman, Vincent L. Fish, Christopher H. Greer, Mark A. Gurwell, Jason W. Henning, Makoto Inoue, Ryan Keisler, Thomas P. Krichbaum, Ru Sen LuDirk Muders, Cornelia Müller, Chi H. Nguyen, Eduardo Ros, Jason Soohoo, Remo P.J. Tilanus, Michael Titus, Laura Vertatschitsch, Jonathan Weintroub, J. Anton Zensus

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Centaurus A (Cen A) is a bright radio source associated with the nearby galaxy NGC 5128 where high-resolution radio observations can probe the jet at scales of less than a light day. The South Pole Telescope (SPT) and the Atacama Pathfinder Experiment performed a single-baseline very-long-baseline interferometry (VLBI) observation of Cen A in 2015 January as part of VLBI receiver deployment for the SPT. We measure the correlated flux density of Cen A at a wavelength of 1.4 mm on a ∼7000 km (5 Gλ) baseline. Ascribing this correlated flux density to the core, and with the use of a contemporaneous short-baseline flux density from a Submillimeter Array observation, we infer a core brightness temperature of 1.4 ×1011 K. This is close to the equipartition brightness temperature, where the magnetic and relativistic particle energy densities are equal. Under the assumption of a circular Gaussian core component, we derive an upper limit to the core size φ = 34.0 ±1.8 μas, corresponding to 120 Schwarzschild radii for a black hole mass of 5.5 ×107 M o.

Original languageEnglish (US)
Article number129
JournalAstrophysical Journal
Issue number2
StatePublished - Jul 10 2018


  • black hole physics
  • galaxies: active
  • galaxies: individual (Centaurus A)
  • submillimeter: general
  • techniques: high angular resolution
  • techniques: interferometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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