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| Paper: |
Multi-Wavelength Study of Sgr A*: The Short Time Scale Variability |
| Volume: |
439, The Galactic Center: a Window to the Nuclear Environment of Disk Galaxies |
| Page: |
285 |
| Authors: |
Yusef-Zadeh, F.; Miller-Jones, J.; Roberts, D.; Wardle, M.; Reid, M.; Dodds-Eden, K.; Porquet, D.; Grosso, N. |
| Abstract: |
To understand the correlation and the radiation mechanism of flare
emission in different wavelength bands, we have coordinated a
number of telescopes to observe Sgr A* simultaneously. We focus only
one aspect of the preliminary results of our multi-wavelength observing
campaigns,
namely, the short time scale variability of emission from Sgr A* in
near-IR, X-ray and radio wavelengths. The structure function analysis
indicate most of the power spectral density is detected on
hourly time
scales in all
wavelength bands. We also report minute time scale variability at 7
and 13mm placing a strong constraint on the nature of the variable
emission. The hourly time scale variability can be explained in the
context
of a model in which the peak frequency of emission shifts toward
lower frequencies as a self-absorbed synchrotron source expands
adiabatically near the acceleration site. The short time scale
variability, on the other hand, places a strong constraint on the size
of the emitting region. Assuming that rapid minute time scale
fluctuations of the emission is optically thick in radio wavelength,
light travel arguments requires relativistic particle energy, thus
suggesting the presence of outflow from Sgr A*. |
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