Speaker: Dr. Farhad Yusef-Zadeh, Northwestern University
Date/Time: March 28, 2025 / 12 noon central.
Location: NCSA 1040
Zoom: https://illinois.zoom.us/j/82318062756?pwd=M3g1MFF6cytsOWFEbmU0UW1XWVoxQT09
Title: Flaring Activity of Sgr A* at infrared with JWST
Abstract:
After a review of what we know about the inner few light years of the Galactic center, I present highlights of our study of monitoring the flux of Sgr A* with JWST/NIRCam at 2.1 and 4.8 microns. JWST observations indicate that the flux of Sgr A* is fluctuating constantly with multiple flares that indicate two distinct populations of particles producing bright synchrotron flares and low-level fluctuations. I will discuss what the spectral index, time delays at infrared wavelengths, power spectrum, and the flux distribution tell us. Modeling of the distinctive behavior of the spectral index as a function of brightness (loop diagrams) has given us a handle on localized magnetic field strengths and the electron density in the accretion flow. Time permitting, I will also discuss the origin of a strong NuSTAR X-ray flare which coincides with a NIRCam infrared flare.