Description |
Coordinated study of flare emission from Sgr A*, the closest supermassive black hole, reveals information about the hydrodynamics, energetics, and accretion behavior of matter within the innermost ten Schwarzschild radii. We propose to use the unique capability of Herschel/SPIRE and XMM in order to characterize flare emission simultaneously at many different wavelengths, the most important of which are completely unavailable from the ground. These measurements will explore the nature of emission at the peak of the spectrum of Sgr A* and will determine the transition wavelength at which the variable emission becomes optically thin. In particular, we will test the prediction that there will be time delay between X-ray flares and the peak emission at 250, 350, and 500 microns. We will take advantage of the calibration stability of Herschel resulting from the L2 placement to detect Sgr A* in SPIRE difference images. The proposed Herschel and XMM observations form the cornerstone of a multi-wavelength campaign that includes observations in near-IR and radio wavelengths. The cross correlation of flare emission at multiple wavelengths will have far-reaching implications for testing the emission mechanism of Sgr A* and for understanding the processes of accretion onto and outflow from the closest supermassive black hole. Lastly, a long flux monitoring of Sgr A* with Herschel over long and nearly continuous baselines will characterize the fraction of time that Sgr A* is active in submm wavelengths and will provide a legacy to unravel the key properties of the best example of a low-luminosity massive black hole. |