Browsing by Author "Ford, H"

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    Evolution in the cluster early-type galaxy size-surface brightness relation at z ≃ 1
    (2005) Holden, BP; Blakeslee, JP; Postman, M; Illingworth, GD; Demarco, R; Franx, M; Rosati, P; Bouwens, RJ; Martel, AR; Ford, H; Clampin, M; Hartig, GF; Benítez, N; Cross, NJG; Homeier, N; Lidman, C; Menanteau, F; Zirm, A; Ardila, DR; Bartko, F; Bradley, LD; Broadhurst, TJ; Brown, RA; Burrows, CJ; Cheng, ES; Feldman, PD; Golimowski, DA; Goto, T; Gronwall, C; Infante, L; Kimble, RA; Krist, JE; Lesser, MP; Magee, D; Mei, S; Meurer, GR; Miley, GK; Motta, V; Sirianni, M; Sparks, WB; Tran, HD; Tsvetanov, ZI; White, RL; Zheng, W
    We investigate the evolution in the distribution of surface brightness, as a function of size, for elliptical and S0 galaxies in the two clusters RDCS J1252.9 - 2927 ( z = 1: 237) and RX J0152.7 - 1357 ( z = 0: 837). We use multicolor imaging with the Advanced Camera for Surveys on the Hubble Space Telescope to determine these sizes and surface brightnesses. Using three different estimates of the surface brightnesses, we find that we reliably estimate the surface brightness for the galaxies in our sample with a scatter of < 0.2 mag and with systematic shifts of <= 0.05 mag. We construct samples of galaxies with early- type morphologies in both clusters. For each cluster, we use a magnitude limit in a band that closely corresponds to the rest- frame B, to magnitude limit of M-B = - 18: 8 at z = 0, and select only those galaxies within the color- magnitude sequence of the cluster or by using our spectroscopic redshifts. We measure evolution in the rest- frame B surface brightness and find - 1: 41 +/- 0: 14 mag from the Coma Cluster of galaxies for RDCS J1252.9 - 2927 and - 0: 90 +/- 0: 12 mag of evolution for RX J0152.7 - 1357, or an average evolution of ( - 1: 13 +/- 0: 15) z mag. Our statistical errors are dominated by the observed scatter in the size - surface brightness relation, sigma = 0: 42 +/- 0: 05 mag for RX J0152.7 - 1357 and sigma = 0: 76 +/- 0: 10 mag for RDCS J1252.9 - 2927. We find no statistically significant evolution in this scatter, although an increase in the scatter could be expected. Overall, the pace of luminosity evolution we measure agrees with that of the fundamental plane of early- type galaxies, implying that the majority of massive early- type galaxies observed at z similar or equal to 1 formed at high redshifts.
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    Evolution of the color-magnitude relation in high-redshift clusters
    (2006) Mei, S; Blakeslee, JP; Stanford, SA; Holden, BP; Rosati, P; Strazzullo, V; Homeier, N; Postman, M; Franx, M; Rettura, A; Ford, H; Illingworth, GD; Ettori, S; Bouwens, RJ; Demarco, R; Martel, AR; Clampin, M; Hartig, GF; Eisenhardt, P; Ardila, DR; Bartko, F; Benítez, N; Bradley, LD; Broadhurst, TJ; Brown, RA; Burrows, CJ; Cheng, ES; Cross, NJG; Feldman, PD; Golimowski, DA; Goto, T; Gronwall, C; Infante, L; Kimble, RA; Krist, JE; Lesser, MP; Menanteau, F; Meurer, GR; Miley, GK; Motta, V; Sirianni, M; Sparks, WB; Tran, HD; Tsvetanov, ZI; White, RL; Zheng, W
    The color-magnitude relation has been determined for the RDCS J0910+5422 cluster of galaxies at redshift z = 1.106. Cluster members were selected from the Hubble Space Telescope Advanced Camera for Surveys (HST ACS) images, combined with ground-based near-IR imaging and optical spectroscopy. The observed early-type color-magnitude relation (CMR) in i(775) - z(850) versus z(850) shows an intrinsic scatter in color of 0.060 +/- 0.009 mag, within 10 from the cluster X-ray emission center. Both the elliptical and the S0 galaxies show small scatter about the CMR of 0.042 +/- 0.010 and 0.044 +/- 0.020 mag, respectively. From the scatter about the CMR, a mean luminosity weighted age t > 3: 3 Gyr (z(f) approximate to 3) is derived for the elliptical galaxies, assuming a simple stellar population modeling (single-burst solar metallicity). Strikingly, the S0 galaxies in RDCS J0910+5422 are systematically bluer in i(775) - z(850), by 0.07 +/- 0.02 mag, than the ellipticals. The ellipticity distribution as a function of color indicates that the face-on S0s in this particular cluster have likely been classified as elliptical. Thus, if anything, the offset in color between the elliptical and S0 populations may be even more significant. The color offset between S0 and E galaxies corresponds to an age difference of approximate to 1 Gyr for a single-burst solar-metallicity model. A solar-metallicity model with an exponential decay in star formation will reproduce the offset for an age of 3.5 Gyr; i.e., the S0s have evolved gradually from star-forming progenitors. The early-type population in this cluster appears to be still forming. The blue early-type disk galaxies in RDCS J0910+5422 likely represent the direct progenitors of the more evolved S0s that follow the same red sequence as elliptical galaxies in other clusters. Thirteen red galaxy pairs are observed, and the galaxies associated in pairs constitute similar to 40% of the CMR galaxies in this cluster.
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    Faint galaxies in deep advanced camera for surveys observations
    (2004) Benítez, N; Ford, H; Bouwens, R; Menanteau, F; Blakeslee, J; Gronwall, C; Illingworth, G; Meurer, G; Broadhurst, TJ; Clampin, M; Franx, M; Hartig, GF; Magee, D; Sirianni, M; Ardila, DR; Bartko, F; Brown, RA; Burrows, CJ; Cheng, ES; Cross, NJG; Feldman, PD; Golimowski, DA; Infante, L; Kimble, RA; Krist, JE; Lesser, MP; Levay, Z; Martel, AR; Miley, GK; Postman, M; Rosati, P; Sparks, WB; Tran, HD; Tsvetanov, ZI; White, RL; Zheng, W
    We present the analysis of the faint galaxy population in the Advanced Camera for Surveys (ACS) Early Release Observation fields VV 29 ( UGC 10214) and NGC 4676. These observations cover a total area of 26.3 arcmin(2) and have depths close to that of the Hubble Deep Fields in the deepest part of the VV 29 image, with 10 sigma detection limits for point sources of 27.8, 27.6, and 27.2 AB magnitudes in the g(F475W), V-F606W, and I-F814W bands, respectively.