J/A+A/618/L10 SgrA* orbital motions with GRAVITY (GRAVITY Collaboration, 2018)
Detection of orbital motions near the last stable circular orbit of the
massive black hole SgrA*.
GRAVITY Collaboration, Abuter, R., Amorim, A., Bauboeck M., Berger J.P.,
Bonnet H., Brandner W., Clenet Y., Coude du Foresto V., de Zeeuw P.T.,
Deen C., Dexter J., Duvert G., Eckart A., Eisenhauer F.,
Foerster Schreiber N.M., Garcia P., Gao F., Gendron E., Genzel R.,
Gillessen S., Guajardo P., Habibi M., Haubois X., Henning T., Hippler S.,
Horrobin M., Huber A., Jimenez-Rosales A., Jocou L., Kervella P.,
Lacour S., Lapeyrere V., Lazareff B., Le Bouquin J.-B., Lena P., Lippa M.,
Ott T., Panduro J., Paumard T., Perraut K., Perrin G., Pfuhl O., Plewa P.M.,
Rabien S., Rodriguez-Coira G., Rousset G., Sternberg A., Straub O.,
Straubmeier C., Sturm E., Tacconi L.J., Vincent F., von Fellenberg S.,
Waisberg I., Widmann F., Wieprecht E., Wiezorrek E., Woillez J., Yazici S.
<Astron. Astrophys. 618, L10 (2018)>
=2018A&A...618L..10G 2018A&A...618L..10G (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources ; Stars, nearby ; Positional data ; Infrared sources
Keywords: Galaxy: centre - black holes physics - gravitation -
relativistic processes
Abstract:
We report the detection of continuous positional and polarization
changes of the compact source SgrA* in high states ('flares') of
its variable near- infrared emission with the near-infrared
GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining
instrument. In three prominent bright flares, the position centroids
exhibit clockwise looped motion on the sky, on scales of typically 150
micro-arcseconds over a few tens of minutes, corresponding to about
30% the speed of light. At the same time, the flares exhibit
continuous rotation of the polarization angle, with about the same
45(±15)-minute period as that of the centroid motions. Modelling
with relativistic ray tracing shows that these findings are all
consistent with a near face-on, circular orbit of a compact polarized
'hot spot' of infrared synchrotron emission at approximately six
to ten times the gravitational radius of a black hole of 4 million
solar masses. This corresponds to the region just outside the
innermost, stable, prograde circular orbit (ISCO) of a
Schwarzschild-Kerr black hole, or near the retrograde ISCO of a highly
spun-up Kerr hole. The polarization signature is consistent with
orbital motion in a strong poloidal magnetic field.
Description:
The GRAVITY instrument combines the four 8m telescopes of the European
Southern Observatory (ESO)-Very Large Telescope (VLT)
interferometrically for 3 milli-arcsec (mas) resolution imaging and
∼20-70microarcsec (µas) astrometry in the K-band (2.2µm)
continuum.
Astrometry of SgrA* 2018 July 22 flare as presented in Fig1.
Objects:
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RA (2000) DE Designation(s)
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17 45 40.04 -29 00 28.2 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
avg.dat 86 10 Jul 22 2018 flare, MJD=58321.9954,
flare positions and relative flux,
average of Pfuhl+ Waisberg (shown in Fig. 1)
wais.dat 86 10 Jul 22 2018 flare, MJD=58321.9954,
flare positions and relative flux Waisberg
analysis (shown Fig. B1)
pfuhl.dat 86 10 Jul 22 2018 flare, MJD=58321.9954,
flare positions and relative flux Pfuhl
analysis (shown in Fig. B1)
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See also:
J/AJ/127/3399 : Sgr A* variability at cm wavelengths (Herrnstein+, 2004)
J/MNRAS/428/2731 : Sgr A* emission at 7mm (Beaklini+, 2013)
J/ApJ/793/120 : Spitzer/IRAC Sgr A* light curve data (Hora+, 2014)
J/ApJ/802/69 : VLA, ALMA and SMA monitoring of Sgr A* (Bower+, 2015)
J/MNRAS/454/1525 : XMM-Newton & Chandra monitoring of Sgr A* (Ponti+, 2015)
J/other/Sci/348.413 : Sgr A East SNR multiwavelength images (Lau+, 2015)
J/ApJ/820/90 : 4yr 1.3mm VLBI observations of SgrA* with EHT
(Fish+, 2016)
J/A+A/589/A116 : Multiwavelength study of Sgr A* (Mossoux+, 2016)
J/A+A/601/A80 : LABOCA 345GHz observations of Sgr A* (Subroweit+, 2017)
J/A+A/618/A35 : ALMA images of the CND and Sgr A* (Goicoechea+, 2018)
Byte-by-byte Description of file: avg.dat wais.dat pfuhl.dat
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Bytes Format Units Label Explanations
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1- 12 F12.9 min Time Time from MJD(0)=58321.9954
14- 25 F12.9 mas x x-offset from SgrA*
27- 37 F11.9 mas e_x x-offset uncertainty
39- 50 F12.9 mas y y-offset from SgrA*
52- 62 F11.9 mas e_y y-offset uncertainty
64- 74 F11.9 --- Flux Flux relative to S2 [15mJy] (1)
76- 86 F11.9 --- e_Flux Flux uncertainty
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Note (1): The flux is given relative to the brightness of the star S2
(mK=14.1; F=15mJy)
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Acknowledgements:
Oliver Pfuhl, pfuhl(at)mpe.mpg.de
(End) Oliver Pfuhl [Garching, Germany], Patricia Vannier [CDS] 02-Nov-2018