Skip to main content

The Far Ultraviolet diffuse background

Historically, the search for the inter-galactic medium(IGM) motivated the search for  the Far Ultraviolet (FUV) backgroundwhich in turn led to a number of experiments and missions.  Decadeslater the focus shifted to FUV as the primary heating and ionizingagent of the atomic phases (warm and cold neutral medium).  Thecurrent view is that the diffuse FUV emission, at high latitudes,has three components: FUV light from hot stars in the Galactic planereflected by dust grains (diffuse galactic light or DGL), FUV fromother galaxies (extra-galactic background light, EBL) and a componentof unknown origin.  During the eighties, there was some discussionthat decaying dark matter particles produced FUV radiation. In mytalk I systematically investigate production of FUV photons by theGalactic Hot Ionized Medium (line emission) and two photon emissionfrom the  Warm Ionized Medium, the general class of low velocityshocks and from Lyman fluorescence in the Solar System (theinterplanetary medium and  the exosphere of Earth).  I concludethat two thirds to perhaps all of the third component can be explainedby the sum of the processes listed above.

AB 107, Codyhall

Shrinivas Kulkarni, Caltech

November 23, 2022
3:00pm - 4:00pm