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Steve Snowden Goddard Space Flight Center 2015 John C. Lindsay Memorial Award Winner |
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"The Soft X-ray Diffuse Background
– Nearly 50 Years of Progress "
THE JOHN C. LINDSAY MEMORIAL LECTURE
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Steve Snowden Goddard Space Flight Center 2015 John C. Lindsay Memorial Award Winner |
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"The Soft X-ray Diffuse Background
– Nearly 50 Years of Progress "
The diffuse soft X-ray background (SXRB) at 1/4 keV was first observed in 1966, nearly 50 years ago. Since then our measurements of the SXRB have expanded to cover the entire sky and have improved greatly in accuracy, resolution, and statistical significance. Meanwhile, models for the structure of the SXRB have evolved on a somewhat circuitous route that has led from a few simple choices to our current understanding of a complex combination of components due to the heliosphere, the very local interstellar medium (the Local Hot Bubble, LHB), the Milky Way halo, the intergalactic and intercluster mediums, and a cosmic background comprised primarily of unresolved active galactic nuclei. Of these, the nature and origin of the LHB emission has been the subject of the greatest controversies. Progress has relied both on multi-wavelength studies spanning the spectrum from the radio to the X-ray, and on interdisciplinary studies combining astrophysics, heliophysics, and planetary science. This talk will provide a review of the evolution of our understanding of the SXRB and discuss the current best model for the distribution of emission responsible for it, with special consideration of the LHB.
About the Speaker
Steve Snowden is an Astrophysicist at NASA's Goddard Space Flight Center where he serves as the Project Scientist for the NASA contribution to the European Space Agency XMM-Newton X-ray observatory program. He received his Ph.D. from the University of Wisconsin-Madison in 1986 and then spent five years as a UW post-doc in Garching, Germany, working on the ROSAT mission producing maps of the 0.1-2.0 keV diffuse X-ray background. In 1993 he joined the ROSAT Guest Observer Facility (GOF) at GSFC and then the XMM-Newton GOF 1997, becoming the Project Scientist in 2009. He has studied the soft X-ray diffuse background and local interstellar medium throughout his entire career with a current excursion into X-ray emission within the heliosphere.