Astrophysical Sciences and Technology Colloquium: The Far Ultraviolet Diffuse Background

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Astrophysical Sciences and Technology Colloquium
The Far Ultraviolet Diffuse Background

Dr. Shri Kulkarni, Ph.D

We are viewing in person in 1125 Carlson Hall, but there is a Zoom link for those unable to attend in person.


Historically, the search for the inter-galactic medium (IGM) motivated the search for the Far Ultraviolet (FUV) background which in turn led to a number ofexperiments and missions. Decades later the focus shifted to FUV as the primary heating and ionizing agent of the atomic phases (warm and cold neutral medium). The current view is that the diffuse FUV emission, at high latitudes, has three components: FUV light from hot stars in the Galactic plane reflected by dust grains (diffuse galactic light or DGL), FUV from other galaxies (extragalactic background light, EBL) and a component of unknown origin. During the eighties, there was some discussion that decaying dark matter particles produced FUV radiation. In his talk Dr. Kulkarni systematically investigates production of FUV photons by the Galactic Hot Ionized Medium (line emission) and two photon emission from the Warm Ionized Medium, the general class of low velocity shocks and from Lyman fluorescence in the Solar System (the interplanetary medium and the exosphere of Earth). He concludes that two thirds to perhaps all ofthe third component can be explained by the sum of the processes listed above.

Speaker Bio:
Dr. Shri Kulkarni is the George Ellery Hale Professor of Astronomy at the California Institute of Technology. He served as Executive Officer for Astronomy (1997-2000) and Director of Caltech Optical Observatories for the period 2006-2018. Dr.Kulkarni obtained his undergradutedegree from the Indian Institute of Technology, Delhi and his PhD from UC Berkeley. He served a brief period as a postdoc at UC Berekelyand Caltech before joining the faculty rank at Caltech in 1987.Prof. Kulkarni's primary interests are the study of compact objects (neutron stars and gamma-ray bursts) and cosmic explosions. He is keenly interested in developing or refining astronomical methodologies.

Intended Audience:
All are welcome. Those with interest in the topic.

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Cheryl Merrell
Event Snapshot
When and Where
November 21, 2022
4:00 pm - 5:00 pm
Room/Location: 1125

Open to the Public

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