z~7 galaxy candidates from NICMOS observations over the HDF South and the CDF-S and HDF-N GOODS fields - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




z~7 galaxy candidates from NICMOS observations over the HDF South and the CDF-S and HDF-N GOODS fields - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We use ~88 arcmin**2 of deep >~26.5 mag at 5 sigma NICMOS data over the twoGOODS fields and the HDF South to conduct a search for bright z>~7 galaxycandidates. This search takes advantage of an efficient preselection over 58arcmin**2 of NICMOS H-band data where only plausible z>~7 candidates arefollowed up with NICMOS J-band observations. ~248 arcmin**2 of deepground-based near-infrared data >~25.5 mag, 5 sigma is also considered in thesearch. In total, we report 15 z-dropout candidates over this area - 7 ofwhich are new to these search fields. Two possible z~9 J-dropout candidates arealso found, but seem unlikely to correspond to z~9 galaxies. The present z~9search is used to set upper limits on the prevalence of such sources. Rigoroustesting is undertaken to establish the level of contamination of our selectionsby photometric scatter, low mass stars, supernovae SNe, and spurious sources.The estimated contamination rate of our z~7 selection is ~24%. Through carefulsimulations, the effective volume available to our z>~7 selections is estimatedand used to establish constraints on the volume density of luminous L*z=3,or -21 mag galaxies from these searches. We find that the volume density ofluminous star-forming galaxies at z~7 is 13 {-5}^{+8}x lower than at z~4 and>25x lower 1 sigma at z~9 than at z~4. This is the most stringent constraintyet available on the volume density of >~L* galaxies at z~9. The presentwide-area, multi-field search limits cosmic variance to <20%. The evolution wefind at the bright end of the UV LF is similar to that found from recent SubaruSuprime-Cam, HAWK-I or ERS WFC3-IR searches. The present paper also includes acomplete summary of our final z~7 z-dropout sample 18 candidates identifiedfrom all NICMOS observations to date over the two GOODS fields, the HUDF,galaxy clusters.



Author: Rychard J. Bouwens UCSC-Leiden, Garth D. Illingworth UCSC, Valentino Gonzalez UCSC, Ivo Labbe OCIW, Marijn Franx Leiden, Christop

Source: https://arxiv.org/







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