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How to Search for Remaining Islands of Neutral Hydrogen in the z ~ 5-6 IGM

Event Details

Event Dates: 

Friday, July 11, 2014 - 12:00pm

Seminar Location: 

  • CASA Conference Room C324

Speaker Name(s): 

Matt Malloy

Speaker Affiliation(s): 

University of Pennsylvania
Seminar Type/Subject

Scientific Seminar Type: 

  • Astrophysics Lunch Seminar

Event Details & Abstract: 

It has been more than 50 years since Gunn & Peterson noted that the lack of prominent absorption troughs in quasar spectra, blueward of the Lyman-alpha line, implied that hydrogen in the intergalactic medium is highly ionized. In 2001, the first observations of "Gunn-Peterson Troughs" were made using z ~ 6 quasar spectra. Despite this occurring more than a decade ago, the precise interpretation of these measurements, and their implications for hydrogen reionization, remain unclear. In this talk, I will briefly describe the possibility that neutral hydrogen islands exist among regions of highly-ionized gas in the IGM as late as z ~ 5 - 6, even though the common wisdom is that hydrogen reionization has completed by z ~ 6. I will then propose three tests by which existing quasar spectra can be used to search for remaining neutral hydrogen islands in the z ~ 5 - 6 IGM.