Joint Chandra/XMM/EVLA Monitoring of the Gas Cloud G2 as it Encounters Sgr A*

A dense, cold dusty gas cloud (dubbed "G2") is on a collision course with SgrA*, the enigmatic radio source and putative supermassive black hole located at the center of our Galaxy. This project will observe that collision with the Chandra X-ray Observatory, together with the EVLA radio telescope and the XMM-Newton X-ray telescope. The full program will consist of six deep (50 ks) exposures of the galactic center black hole (SgrA*) during its encounter with a gas cloud called “G2”. Six simultaneous EVLA observations (7 hours each) will also be acquired, along with a single 30ks XMM observation to accomplish higher X-ray spectral resolution (obtained in the Sept/Oct 2013 time frame). The technical and scientific work on this project include (but are not limited to) the following: 1. Detection and characterization of X-ray flares in the Chandra data intrinsic to SgrA* or resulting from the G2 encounter 2. Detection and characterization of radio flares either coincident with the X-ray flares or with physically interesting delays 3. Chandra X-ray spectral analysis for bright outbursts and/or from deep X-ray co-adds 4. Detailed study of SgrA*’s quiescent state in the X-ray and radio during non-flare epochs 5. X-ray spectral analysis based on the 30ks XMM exposure 6. Theoretical modeling and contextualization of multiwavelength data for (1) predicted periods of enhanced accretion onto SgrA*, (2) implications for low-luminosity AGN accretion disks and jets, and (3) the composition and structure of G2 itself 7. Analysis of other X-ray and radio variables in the field both within and between the multiple Chandra/EVLA exposures The proposing team has extensive experience in all of these areas; Northwestern-based scientists, Dr. Daryl Haggard and Dr. Farhad Yusef-Zadeh will be the principal leads on the X-ray and radio analysis, respectively.