Symmetric Achromatic Variability: A powerful new gravitational lensing probe?

Harish Vedantham - April 24, 2017 at 12:10 pm

I will report on our recent discovery of a new form of radio variability in active galactic nuclei --- symmetric achromatic variations (SAV). SAV have a high degree of time-symmetry and are observed to be frequency independent between 15 and 300 GHz. I will argue that SAVs are likely caused by gravitational lensing of relativistically moving source components in the jet of an active galactic nuclei. Based on known properties of such components, the lens can be shown to be in the intermediate mass regime (10^3-10^6 solar masses). This mass scale has been thus far inaccessible to traditional gravitational lensing techniques. I will discuss key falsifiable predictions of the lensing hypothesis, and plans to detect the putative lensed images using global mm-wave VLBI observations at a resolution of few tens of micro-arcseconds.

The seminar will be held in 131A Campbell Hall.

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