230 GHz VLBI observations of M87: event-horizon-scale structure at the enhanced very-high-energy γ-ray state in 2012
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Author
Akiyama, Kazunori
Lu, Ru-Sen
Fish, Vincent
Broderick, Avery
Dexter, Jason
Hada, Kazuhiro
Kino, Motoki
Nagai, Hiroshi
Honma, Mareki
Algaba, Juan
Asada, Keiichi
Brinkerink, Christiaan
Bower, Geoffrey
Cappallo, Roger
Crew, Geoffrey
Dexter, Matt
Dzib, Sergio
Freund, Robert
Friberg, Per
Ho, Paul
Inoue, Makoto
Krichbaum, Thomas
Loinard, Laurent
MacMahon, David
Marrone, Daniel
Nakamura, Masanori
Nagar, Neil
Ortiz-Leon, Gisela
Plambeck, Richard
Pradel, Nicolas
Rogers, Alan
Roy, Alan
SooHoo, Jason
Tavares, Jonathan-León
Tilanus, Remo
Titus, Michael
Wagner, Jan
Zensus, Anton
Ziurys, Lucy
Note: Order does not necessarily reflect citation order of authors.
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https://doi.org/10.1088/0004-637x/807/2/150Metadata
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Akiyama, Kazunori, Ru-Sen Lu, Vincent L. Fish, Sheperd S. Doeleman, Avery E. Broderick, Jason Dexter, Kazuhiro Hada, et al. 2015. “230 GHz VLBI observations of M87: event-horizon-scale structure at the enhanced very-high-energy γ-ray state in 2012.” The Astrophysical Journal 807 (2) (July 9): 150. doi:10.1088/0004-637x/807/2/150.Abstract
We report on 230 GHz (1.3 mm) VLBI observations of M87 with the Event Horizon Telescope using antennas on Mauna Kea in Hawaii, Mt. Graham in Arizona and Cedar Flat in California. For the first time, we have acquired 230 GHz VLBI interferometric phase information on M87 through measurement of closure phase on the triangle of long baselines. Most of the measured closure phases are consistent with 0◦ as expected by physically-motivated models for 230 GHz structure such as jet models and accretion disk models. The brightness temperature of the event-horizon-scale structure is ∼ 1 × 1010 K derived from the compact flux density of ∼ 1 Jy and the angular size of ∼ 40 µas ∼ 5.5 Rs, which is broadly consistent with the peak brightness of the radio cores at 1-86 GHz located within ∼ 102 Rs. Our observations occurred in the middle of an enhancement in very-high-energy (VHE) γ-ray flux, presumably originating in the vicinity of the central black hole. Our measurements, combined with results of multi-wavelength observations, favor a scenario in which the VHE region has an extended size of ∼20-60 Rs.Terms of Use
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