J/ApJ/807/150 230GHz VLBI observations of M87 (Akiyama+, 2015)
230 GHz VLBI observations of M87: event-horizon-scale structure during an
enhanced very-high-energy γ-ray state in 2012.
Akiyama K., Lu R.-S., Fish V.L., Doeleman S.S., Broderick A.E., Dexter J.,
Hada K., Kino M., Nagai H., Honma M., Johnson M.D., Algaba J.C., Asada K.,
Brinkerink C., Blundell R., Bower G.C., Cappallo R., Crew G.B., Dexter M.,
Dzib S.A., Freund R., Friberg P., Gurwell M., Ho P.T.P., Inoue M.,
Krichbaum T.P., Loinard L., MacMahon D., Marrone D.P., Moran J.M.,
Nakamura M., Nagar N.M., Ortiz-Leon G., Plambeck R., Pradel N.,
Primiani R.A., Rogers A.E.E., Roy A.L., Soohoo J., Tavares J.-L.,
Tilanus R.P.J., Titus M., Wagner J., Weintroub J., Yamaguchi P.,
Young K.H., Zensus A., Ziurys L.M.
<Astrophys. J., 807, 150 (2015)>
=2015ApJ...807..150A 2015ApJ...807..150A (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Interferometry ; Radio continuum
Keywords: galaxies: active; galaxies: individual: M87;
galaxies: jets; radio continuum: galaxies;
techniques: high angular resolution; techniques: interferometric
Abstract:
We report on 230GHz (1.3mm) 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 230GHz 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 230GHz structure such as jet models and accretion
disk models. The brightness temperature of the event-horizon-scale
structure is ∼1x1010K derived from the compact flux density of ∼1Jy
and the angular size of ∼40µas∼5.5Rs, which is broadly consistent
with the peak brightness of the radio cores at 1-86GHz located within
∼102Rs. 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 ∼20-60Rs.
Description:
M87 and several calibrator sources were observed with four stations at
three sites in 2012 on the nights of March 15, 20 and 21 (days 75, 80
and 81): a phased array of the Submillimeter Array (SMA) antennas and
the James Clerk Maxwell Telescope (JCMT) on Mauna Kea in Hawaii, the
Arizona Radio Observatory's Submillimeter Telescope (ARO/SMT) on Mt.
Graham in Arizona, and both a single antenna and a phased array of
eight antennas of the Combined Array for Research in Millimeter-wave
Astronomy (CARMA) in Cedar Flat in California.
Observations were performed at two bands centered at 229.089 and
229.601GHz (low and high band) with 480MHz bandwidths with the
exception of the single CARMA antenna, which observed only the low
band.
Objects:
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RA (ICRS) DE Designation(s)
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12 30 49.42 +12 23 28.0 M87 = NAME VIRGO GALAXY
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 87 17 Closure phase of M87
table3.dat 47 70 Gain-corrected visibility amplitudes of M87
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See also:
J/ApJ/772/13 : VLBI observations of 3C 279 at 230GHz (Lu+, 2013)
J/other/Sci/338.355 : 1.3mm VLBI detections of M87 (Doeleman+, 2012)
J/ApJ/727/L36 : 1.3mm VLBI observations of Sagittarius A* (Fish+, 2011)
J/ApJ/613/279 : ACS Virgo Cluster Survey. III. M87 (Jordan+, 2004)
J/ApJS/36/53 : 2380 MHz survey of bright galaxies (Dressel+, 1978)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 "YYYYDDD" Date Date of the observation
9- 13 A5 "h:m" Time UTC time of the observation
15- 19 A5 --- Tri Observational triangle; XYZ (G1)
21- 29 F9.3 --- uXY Baseline length of XY baseline
in RA direction (G2)
31- 39 F9.3 --- vXY Baseline length of XY baseline
in Dec direction (G2)
41- 48 F8.3 --- uYZ Baseline length of YZ baseline
in RA direction (G2)
50- 57 F8.3 --- vYZ Baseline length of YZ baseline
in Dec direction (G2)
59- 65 F7.3 --- uZX Baseline length of ZX baseline
in RA direction (G2)
67- 74 F8.3 --- vZX Baseline length of ZX baseline
in Dec direction (G2)
76- 81 F6.2 deg Phase Closure phase
83- 87 F5.2 deg e_Phase The 1σ error in Phase
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 "YYYYDDD" Date Date of the observation
9- 13 A5 "h:m" Time UTC time of the observation
15- 17 A3 --- Baseline Baseline (G1)
19- 27 F9.3 --- u Baseline length in RA direction (G2)
29- 37 F9.3 --- v Baseline length in Dec direction (G2)
39- 42 F4.2 Jy Flux [0/1.2]?=0 Correlated flux density at 230GHz
44- 47 F4.2 Jy e_Flux [0/0.2]?=0 The 1σ error in Flux
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Global notes:
Note (G1): Code as follows:
S = Arizona Radio Observatory's Submillimeter Telescope (ARO/SMT)
on Mt. Graham, Arizona;
P = A phased array of the Submillimeter Array (SMA) antennas and the
James Clerk Maxwell Telescope (JCMT) on Mauna Kea in Hawaii;
F = A single antenna of the Combined Array for Research in Millimeter-Wave
Astronomy (CARMA) on Cedar Flat in California.
D = A phased array of eight CARMA antennas.
Note (G2): In units of Mega-λ where λ is the observational
wavelength.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Oct-2015