1.3 mm WAVELENGTH VLBI OF SAGITTARIUS A*: DETECTION OF TIME-VARIABLE EMISSION ON EVENT HORIZON SCALES

By Vincent L. Fish, Sheperd S. Doeleman, C. Beaudoin, R. Blundell, D. E. Bolin, G. Bower, R. Chamberlin, R. Freund, P. Friberg, M. Gurwell and 20 more. 2010

161 citations recorded by the source corpus.

Sagittarius A*, the ∼4 × 106 M☉ black hole candidate at the Galactic center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength very long baseline interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the Arizona Radio Observatory's Submillimeter Telescope on Mt. Graham in Arizona, and two telescopes of the CARMA array at Cedar Flat in California. Both Sgr A* and the quasar calibrator 1924−292 were observed over three consecutive nights, and both sources were clearly detected on all baselines. For the first time, we are able to extract 1.3 mm VLBI interferometer phase information on Sgr A* through measurement of closure phase on the triangle of baselines. On the third night of observing, the correlated flux density of Sgr A* on all VLBI baselines increased relative to the first two nights, providing strong evidence for time-variable change on scales of a few Schwarzschild radii. These results suggest that future VLBI observations with greater sensitivity and additional baselines will play a valuable role in determining the structure of emission near the event horizon of Sgr A*.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/9317821a9f2146ba1e40410d92fd2179daff75e0

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In Astronomy and Astrophysics

1. T. Johannsen
2. Ramesh Narayan
3. F. Yuan
4. J. Dexter
5. Paolo Pani
6. V. Cardoso
7. Cosimo Bambi
8. Dimitrios Psaltis

In Nuclear and High Energy Physics

1. T. Johannsen
2. Ramesh Narayan
3. V. Cardoso
4. F. Yuan
5. J. Dexter
6. Paolo Pani
7. Dimitrios Psaltis
8. J. McKinney

Citations in the corpus

• On the charge of the Galactic centre black hole (2018, unknown): “Zakharov (2014) uses an argument that the measured core size of Sgr A* of ∼ 40µas (Doeleman et al. 2008; Fish et al. 2011) is more consistent with the Reissner-Nordström black hole with the charge close to the extremal value of Qnorotmax than with the Schwarzschild black hole whose shadow is…”
• Imaging the Schwarzschild-radius-scale Structure of M87 with the Event Horizon Telescope Using Sparse Modeling (2017, background): “…on 1.3 mm VLBI observations with the Event Horizon Telescope (EHT; Doeleman et al. 2009) has succeeded in resolving compact structures of a few Rs in the vicinity of the SMBHs in both Sgr A* and M87 (e.g. Doeleman et al. 2008, 2012; Fish et al. 2011, 2016; Akiyama et al. 2015; Johnson et al. 2015).”
• HIGH-RESOLUTION LINEAR POLARIMETRIC IMAGING FOR THE EVENT HORIZON TELESCOPE (2016, background): “Previous observations with three EHT baselines have constrained the size of the 1.3 mm emission region to scales on the order of the lensed Schwarzschild radius in SgrA* (Doeleman et al. 2008; Fish et al. 2011) and M87 (Doeleman et al. 2012).”
• PHOTON RINGS AROUND KERR AND KERR-LIKE BLACK HOLES (2013, result): “Similar observations also detected time variability on these scales in Sgr A* (Fish et al. 2011).”
• TESTING THE NO-HAIR THEOREM WITH EVENT HORIZON TELESCOPE OBSERVATIONS OF SAGITTARIUS A* (2013, methodology): “The currently available data for Sgr A* is comprised of observations during two days in 2007 (April 11 and 12, Doeleman et al. 2008) and three days in 2009 (April 5–7, Fish et al. 2011).”
• Hot Accretion Flows Around Black Holes (2014, background): “In recent years, ultra-high angular resolution millimeter wave interferometry has become a reality and the first detections have been made of event-horizon scale structure in Sgr A* (Doeleman et al. 2008, Fish et al. 2011) and M87 (Doeleman et al. 2012).”
• INTO THE LAIR: GRAVITATIONAL-WAVE SIGNATURES OF DARK MATTER (2013, background): “The exact nature of the object at the center of our galaxy will soon be 2 strongly constrained by observations (Doeleman et al. 2008; Fish et al. 2011; Eisenhauer et al. 2008), making this an exciting time to theoretically model and understand alternatives.”
• The size of the jet launching region in M87 (2011, methodology): “The most recent mm-VLBI campaign observed M87 as well as Sgr A* (Fish et al. 2011), but the data are as yet unpublished.”