CfA OIR Division Lunch Talks
Monday, April 27, 3:00 pm, Pratt Conference Room
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How will the James Webb Space Telescope measure
First Light, Reionization, and Galaxy Assembly:
The New Frontier after Hubble

Rogier A. Windhorst (JWST Interdisciplinary Scientist, Arizona State Univ.)

I will review how the 6.5 meter James Webb Space Telescope (JWST) --- after its launch in 2018 --- can measure the epochs of First Light, Reionization, Galaxy Assembly, and Supermassive Black-Hole Growth building on recent results from the Hubble Wide Field Camera 3.

First, I'll briefly summarize the significant technical progress on the design and fabrication of JWST: more than 98% of its launch mass has been built, passed final design, or is being built as of spring 2015. All JWST's 18 flight mirrors have been gold-coated with an optical performance that meets or exceed specs. All of JWST's scientific instruments were delivered to NASA GSFC and tested from mid 2013---2014. I will briefly summarize the path from today till launch, still planned for October 2018.

Next, I will briefly review the search for z=9--11 objects in the Hubble UltraDeep and Frontier Fields and their current limitations. I will show what combination of area, depth, and wavelength coverage are needed for JWST to detect a sufficient number of First Light objects, and to measure their evolving luminosity function (LF). JWST will map the epoch of First Light through Pop III-star dominated objects at redshifts z~8--15, and its transition to the first Pop II stars in dwarf galaxies at z~<9. JWST will measure the evolution of the Schechter LF at z~6--15. A steep faint-end of the dwarf galaxy LF may have provided the UV-flux needed to start and finish cosmic reionization. JWST will also image the first quasars at redshifts z>6 in detail.

I will argue that gravitational lensing from foreground galaxy clusters and high-concentration groups will need to be used to maximize the number of First Light objects (z~>12-15) detected with JWST. Last, I will address how many random Webb Deep Fields (WDFs) may need to be observed with JWST to see First Light, compared to the best lensing targets.