期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 727, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/727/2/L36
关键词
Galaxy: center; submillimeter: general; techniques: high angular resolution; techniques: interferometric
资金
- National Science Foundation (NSF)
- NSF
- Smithsonian Institution
- Academia Sinica
- CARMA
- NSFATI program
- Grants-in-Aid for Scientific Research [21244019] Funding Source: KAKEN
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [0905844] Funding Source: National Science Foundation
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [838261] Funding Source: National Science Foundation
Sagittarius A*, the similar to 4 x 10(6) M(circle dot) 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*.
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