230 GHz VLBI OBSERVATIONS OF M87: EVENT‐HORIZON‐SCALE STRUCTURE DURING AN ENHANCED VERY‐HIGH‐ENERGY γ‐RAY STATE IN 2012
Name
Akiyama-2015-230 GHz VLBI OBSERVA.pdf
Size
1.06 MB
Format
Adobe PDF
Checksum (MD5)
31610c6ce13e3a6eab81daf5f9c5b49d
Author(s)
Lu, Rusen
Fish, Vincent L.
Doeleman, Sheperd Samuel
Cappallo, Roger J.
Crew, Geoffrey B.
Rogers, Alan E. E.
SooHoo, Jason G.
Titus, Michael A.
Date Issued
July 2015
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Akiyama, Kazunori, Ru-Sen Lu, Vincent L. Fish, Sheperd S. Doeleman, Avery E. Broderick, Jason Dexter, Kazuhiro Hada, et al. “230 GHz VLBI OBSERVATIONS OF M87: EVENT‐HORIZON‐SCALE STRUCTURE DURING AN ENHANCED VERY‐HIGH‐ENERGY γ‐RAY STATE IN 2012.” The Astrophysical Journal 807, no. 2 (July 9, 2015): 150. © 2015 The American Astronomical Society
Version
Final published version
Abstract
We report on 230 GHz (1.3 mm) very long baseline interferometry (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 the 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 X 10[superscript 10] K derived from the compact flux density of ~1 Jy and the angular size of ~40 µas ~ 5.5 R[subscript s], which is broadly consistent with the peak brightness of the radio cores at 1–86 GHz located within ~10[superscript 2] R[subscript s]. 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 R[subscript s].
MIT Department
Haystack Observatory
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1088/0004-637X/807/2/150
