Joseph Caruana (AIP)

The search for the most distant galaxies in the Universe
When Nov 01, 2013 from 10:30 AM to 12:00 PM
What
  • Colloquium
Where SH, Lecture hall
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Recent years have seen a concerted effort at pushing observations of galaxies to ever higher redshifts.  The advent of Wide Field Camera 3 (WFC3) on the Hubble Space Telescope opened up new doors for the pursuit of extremely high redshift galaxies, with several groups making use of the Lyman-break technique to identify high-z candidates.  However, while the number of selected candidate galaxies at z > 6.5 is substantial, the number of spectroscopically confirmed objects (via follow-up observations aimed to detect Lyman-alpha emission in these objects) remains very small.  In this talk I will review the progress made in the field and will also comment about the very difficult challenges and some of the pitfalls associated with this endeavour, which from time to time have led to conflicting results.

Later in the talk I will focus the attention on the use of Lyman-alpha emitting galaxies as a cosmological tool to probe the neutral fraction of Hydrogen in the universe and to investigate the era of reionization.  Current observations seem to suggest that there is a drop in the number of Lyman-alpha emitters at z > 7 when compared to lower redshifts.  The possible meanings of this apparent number drop will be discussed.