J/ApJ/727/L36 1.3mm VLBI observations of Sagittarius A* (Fish+, 2011)
1.3 mm wavelength VLBI of Sagittarius A*: detection of time-variable emission
on event horizon scales.
Fish V.L., Doeleman S.S., Beaudoin C., Blundell R., Bolin D.E., Bower G.C.,
Chamberlin R., Freund R., Friberg P., Gurwell M.A., Honma M., Inoue M.,
Krichbaum T.P., Lamb J., Marrone D.P., Moran J.M., Oyama T., Plambeck R.,
Primiani R., Rogers A.E.E., Smythe D.L., Soohoo J., Strittmatter P.,
Tilanus R.P.J., Titus M., Weintroub J., Wright M., Woody D., Young K.H.,
Ziurys L.M.
<Astrophys. J., 727, L36 (2011)>
=2011ApJ...727L..36F 2011ApJ...727L..36F
ADC_Keywords: Millimetric/submm sources ; Interferometry
Keywords: Galaxy: center - submillimeter: general -
techniques: high angular resolution - techniques: interferometric
Abstract:
Sagittarius A*, the ∼4x106M☉ 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 1.3mm 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 1.3mm 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.
Description:
Sgr A* and several calibrator sources were observed with four
telescopes at three observatories: the James Clerk Maxwell Telescope
(JCMT; henceforth also J) on Mauna Kea in Hawaii, the Arizona Radio
Observatory's Submillimeter Telescope (ARO/SMT; S) in Arizona, and two
telescopes of the Combined Array for Research in Millimeter-wave
Astronomy (CARMA; C and D, located ∼60m apart) in California.
Observations occurred over three nights: 2009 April 5-7 (days 95-97).
Sources were observed in left circular polarization in two 480MHz
bandwidths centered at 229.089 and 229.601GHz (low and high bands).
Objects:
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RA (2000) DE Designation(s)
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19 24 51.06 -29 14 30.1 1924-292 = QSO B1921-293
17 45 40.04 -29 00 28.1 Sgr A* = NAME Sgr A*
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 53 150 Gain-corrected detections of 1924-292 and Sgr A*
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See also:
J/MNRAS/419/1097 : The EVN Galactic Plane Survey - EGaPS (Petrov, 2012)
J/AJ/142/35 : The VLBA Galactic Plane Survey (VGaPS) (Petrov+, 2011)
J/ApJ/721/137 : The Bolocam Galactic Plane Survey (BGPS) (Bally+, 2010)
J/ApJ/699/186 : VLA observations of the Galactic center (Zhao+, 2009)
J/PASJ/52/631 : Galactic plane VERA survey (Honma+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Source name (1924-292 or Sgr A*)
10- 17 A8 "YYYY-DDD" Obs.date Observation day of the year (2009-095/2009-097)
19- 23 A5 "h:m" Obs.time UT time of the observation
25- 26 A2 --- Base Baseline designation (JC, JD, SC or SJ)
28- 31 A4 --- Band Band (low [229.089GHz], high [229.601GHz] or
both)
33- 37 I5 --- u The u visibility in units of Mλ
39- 43 I5 --- v The v visibility in units of Mλ
45- 48 F4.2 Jy Flux Flux density
50- 53 F4.2 Jy e_Flux The 1σ uncertainty in Flux
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History:
From electronic version of the journal
(End) Greg Scwharz [AA], Emmanuelle Perret [CDS] 31-Aug-2012