Image of Alice in Wonderland at the Mad Hatter's tea party You are cordially invited to afternoon tea and biscuits wine and chocolate

Astronomy Tea Talks at Caltech

Mondays, Hameetman auditorium (Cahill)
Tea:  4.00pm
Talk: 4.15pm

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2011 - 2012 season:
28 November 2011 Kate Whitaker (Yale)

'The Build Up of Red Galaxies with the NEWFIRM Medium-Band Survey'

I will present results from a unique near-IR medium bandwidth survey. Using medium-band filters to better sample the most prominent spectral feature of galaxies at z>1, the NEWFIRM Medium-Band Survey (NMBS) is able to achieve a factor of 2-3 improvement in the accuracies of the photometric redshifts at z>1. With a sample of 40,000 galaxies at 0 < z < 3, we show evidence for a clear bimodal color distribution between quiescent and star-forming galaxies that persists to z~3. Amongst the massive quiescent galaxies, we measure an increase in the intrinsic color scatter at high redshifts. This scatter in color arises from the spread in ages of the quiescent galaxies, where we find a large population of young quiescent ("post-starburst") galaxies at z >1 that are almost non-existent at z <1. Interestingly, these recently quenched galaxies at z>1 are not larger, and possibly even smaller, than older galaxies at those redshifts. These results suggest that the size growth of the quiescent population is not largely driven by the continuous transformations of larger, star-forming galaxies: in that case, the youngest quiescent galaxies would also be the largest.
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Last modified on 11th Nov 2011 by Marco Viero.  

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