Astronomy and Astrophysics, volume 540A, 41-41 (2012/4-1)
Flares and variability from Sagittarius A*: five nights of simultaneous multi-wavelength observations.
HAUBOIS X., DODDS-EDEN K., WEISS A., PAUMARD T., PERRIN G., CLENET Y., GILLESSEN S., KERVELLA P., EISENHAUER F., GENZEL R. and ROUAN D.
Abstract (from CDS):
We report on simultaneous observations and modeling of mid-infrared (MIR), near-infrared (NIR), and submillimeter (sub-mm) emission of the source Sgr A* associated with the supermassive black hole at the center of our Galaxy. Our goal was to monitor the activity of Sgr A* at different wavelengths in order to constrain the emitting processes and gain insight into the nature of the close environment of Sgr A*. We used the MIR instrument VISIR in the BURST imaging mode, the adaptive optics assisted NIR camera NACO, and the sub-mm antenna APEX to monitor Sgr A* over several nights in July 2007. The observations reveal remarkable variability in the NIR and sub-mm during the five nights of observation. No source was detected in the MIR, but we derived the lowest upper limit for a flare at 8.59µm (22.4mJy with A8.59µm=1.6±0.5). This observational constraint makes us discard the observed NIR emission as coming from a thermal component emitting at sub-mm frequencies. Moreover, comparison of the sub-mm and NIR variability shows that the highest NIR fluxes (flares) are coincident with the lowest sub-mm levels of our five-night campaign involving three flares. We explain this behavior by a loss of electrons to the system and/or by a decrease in the magnetic field, as might conceivably occur in scenarios involving fast outflows and/or magnetic reconnection.
accretion, accretion disks - black hole physics - Galaxy: center - Galaxy: nucleus
Paragraph 2.3 calibrator G10.62 is GAL 010.62-00.38 and G5.89 is GAL 005.89-00.39 in Simbad.
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