Expanding the Search for Galaxies at z~7-10 with New NICMOS Parallel Fields Alaina Henry (UCLA) Matt Malkan, Brian Siana, Matthew Ashby, Carrie Bridge, Ranga-Ram Chary, James Colbert, Mauro Giavalisco, Harry Teplitz, Patrick McCarthy The First Galaxies: The initial conditions of galaxy evolution Clues point to z > 7 as important Mature and massive galaxies at z~6 (some have 1010 M and ages of a few 100 Myrs; Eyles et al. 2005, 2007; Yan et al. 2006) Star formation at z>7 needed for reionization? Lyman Break Galaxies at z~7 Z~7 z 900 J H 1400 K 1900 Deep near infrared data needed Wide area surveys for z>7 galaxies GOODS-S and ESO Remote Galaxy Survey cover ~150 + 225 arcmin2 (Mannucci et al. 2007; Stanway et al. 2008) Upper limit consistent with z~6 NICMOS Parallel Imaging Survey (Henry et al. 2007, 2008) Advantage: Space based IR sensitivity A z~9 candidate? Spitzer/IRAC followup of NICMOs Parallel Survey Very Tentative! z~3 Efforts to confirm? Would imply an LF and cosmic SFR density similar to z~3 z~9 Pencil beam surveys are now uncovering galaxies at z>7 Bouwens et al. (2008) Lensing Surveys for z>7 galaxies Bouwens et al. z~6 Richard et al. (2008) report 10 possible z~7 candidates Bouwens et al. (2008) argue that none are z~7 Bouwens et al. z~7 Richard et al. (2008) New NICMOS Parallel Observations Increases deep NICMOS area by 60% + 2 fields in SSA22 Total: 14.4 arcmin2 Sensitivities: J110 = 26.027.5 AB Selection of z>7 candidates (Only four sources undetected at bands shorter than z) No z>7 candidates found The UV luminosity function ~1±1 z~7 galaxy expected from current estimates of the luminosity function (Bouwens et al. 2008) MUV > -20 for typical * (Filled Circles = Bouwens et al. 2007, 2008) Trends in LF evolution continue beyond z~6 Maintaining an ionized IGM? To maintain a completely ionized IGM at z~7 (e.g. Madau et al. 1999): Assumes Salpeter IMF and Solar metallicity For C~10, and fesc ~ 0.1 (???), at z~7 this gives 0.13 Msun yr-1 Mpc-3 Estimate from our data: several times too small Conclusions 14.4 arcmin2 of new NICMOS Parallel fields reveal no z>7 candidates Agrees with Bouwens et al. (2008) tentative z~7 LF Future prospects for expanding z~7-10 samples WFC3 (PIs Illingworth, Trenti, Yan)