Browsing by Author "Magee, D"

Now showing 1 - 4 of 4
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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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    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.
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    Luminosity functions of the galaxy cluster MS 1054-0321 at z=0.83 based on ACS photometry
    (2005) Goto, T; Postman, M; Cross, NJG; Illingworth, GD; Tran, K; Magee, D; Franx, M; Benítez, N; Bouwens, RJ; Demarco, R; Ford, HC; Homeier, NL; Martel, AR; Menanteau, F; Clampin, M; Hartig, GF; Ardila, DR; Bartko, F; Blakeslee, JP; Bradley, LD; Broadhurst, TJ; Brown, RA; Burrows, CJ; Cheng, ES; Feldman, PD; Golimowski, DA; Gronwall, C; Holden, B; Infante, L; Jee, MJ; Krist, JE; Lesser, MP; Mei, S; Meurer, GR; Miley, GK; Motta, V; Overzier, R; Sirianni, M; Sparks, WB; Tran, HD; Tsvetanov, ZI; White, RL; Zheng, W; Zirm, A
    We present new measurements of the galaxy luminosity function (LF) and its dependence on local galaxy density, color, morphology, and clustocentric radius for the massive z = 0.83 cluster MS 1054-0321. Our analyses are based on imaging performed with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST) in the F606W, F775W, and F850LP passbands and extensive spectroscopic data obtained with the Keck Low-Resolution Imaging Spectrograph. Our main results are based on a spectroscopically selected sample of 143 cluster members with morphological classifications derived from the ACS observations. Our three primary findings are (1) the faint-end slope of the LF is steepest in the bluest filter, (2) the LF in the inner part of the cluster (or highest density regions) has a flatter faint-end slope, and (3) the fraction of early-type galaxies is higher at the bright end of the LF, and gradually decreases toward fainter magnitudes. These characteristics are consistent with those in local galaxy clusters, indicating that, at least in massive clusters, the common characteristics of cluster LFs are established at z = 0.83. These results provide additional support for the hypothesis that the formation of galaxies in MS 1054-0321 began at redshifts considerably greater than unity. We also find a 2 sigma deficit of intrinsically faint, red galaxies (i(775)-z(850) greater than or equal to 0.5, M-i > -19) in this cluster. Although the significance is marginal, this trend may suggest that faint, red galaxies (which are common in z < 0.1 rich clusters) have not yet been created in this cluster at z = 0.83. The giant-to-dwarf ratio in MS 1054-0321 starts to increase inwards of the virial radius or when Sigma > 30 Mpc(-2), coinciding with the environment where the galaxy star formation rate and the morphology-density relation start to appear. A physical process that begins to become effective at around the virial radius or Sigma similar to 30 Mpc(-2) may thus be responsible for the evolution of color and luminosity of cluster galaxies.
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    Star formation at z ∼ 6
    (2003) Bouwens, RJ; Illingworth, GD; Rosati, P; Lidman, C; Broadhurst, T; Franx, M; Ford, HC; Magee, D; Benítez, N; Blakeslee, JP; Meurer, GR; Clampin, M; Hartig, GF; Ardila, DR; Bartko, F; Brown, RA; Burrows, CJ; Cheng, ES; Cross, NJG; Feldman, PD; Golimowski, DA; Gronwall, C; Infante, L; Kimble, RA; Krist, JE; Lesser, MP; Martel, AR; Menanteau, F; Miley, GK; Postman, M; Sirianni, M; Sparks, WB; Tran, HD; Tsvetanov, ZI; White, RL; Zheng, W
    Using an i - z dropout criterion, we determine the space density of z similar to 6 galaxies from two deep ACS GTO fields with deep optical-IR imaging. A total of 23 objects are found over 46 arcmin(2), or similar to0.5 +/- 0.1 objects arcmin(-2) down to z(AB) similar to 27.3 (6 sigma), or a completeness-corrected similar to0.5 +/- 0.2 objects arcmin(-2) down to z(AB) similar to 26.5 (including one probable z similar to 6 active galactic nucleus). Combining deep ISAAC data for our RDCS 1252-2927 field (J(AB) similar to 25.7 and K-s;AB similar to 25.0; 5 sigma) and NICMOS data for the Hubble Deep Field North (J(110;AB) and H-160; AB similar to 27.3, 5 sigma), we verify that these dropouts have relatively. at spectral slopes, as one would expect for star-forming objects at z similar to 6. Compared with the average-color (beta = -1.3) U-dropout in the Steidel et al. z similar to 3 sample, i-dropouts in our sample range in luminosity from similar to1.5L(*) (z(AB) similar to 25.6) to similar to0.3L(*) (z(AB) similar to 27.3) with the exception of one very bright candidate at z(850; AB) similar to 24.2. The half-light radii vary from 0."09 to 0."21, or 0.5 kpc to 1.3 kpc. We derive the z similar to 6 rest-frame UV luminosity density (or star formation rate density) by using three different procedures. All three procedures use simulations based on a slightly lower redshift (z similar to 5) V-606-dropout sample from Chandra Deep Field-South ACS images. First, we make a direct comparison of our findings with a no-evolution projection of this V-dropout sample, allowing us to automatically correct for the light lost at faint magnitudes or lower surface brightnesses. We find 23% +/- 25% more i-dropouts than we predict, consistent with no strong evolution over this redshift range. Adopting previous results to z similar to 5, this works out to a mere 20% +/- 29% drop in the luminosity density from z similar to 3 to z similar to 6. Second, we use the same V-dropout simulations to derive a detailed selection function for our i-dropout sample and compute the UV-luminosity density [7.2 +/- 2.5) _x 10(25) ergs s(-1) Hz(-1) Mpc(-3) down to z(AB) similar to 27]. We find a 39% +/- 21% drop over the same redshift range (z similar to 3-6), consistent with the first estimate. This is our preferred value and suggests a star formation rate of 0.0090 +/- 0.0031 M-. yr(-1) Mpc(-3) to z(AB) similar to 27, or similar to 0.036 +/- 0.012 M-. yr(-1) Mpc(-3) by extrapolating the luminosity function to the faint limit, assuming alpha = - 1.6. Third, we follow a very similar procedure, except that we assume no incompleteness, and find a rest-frame continuum luminosity that is similar to2-3 times lower than our other two determinations. This final estimate is to be taken as a lower limit and is important if there are modest changes in the colors or surface brightnesses from z similar to 5 to z similar to 6 (the other estimates assume no large changes in the intrinsic selectability of objects). We note that all three estimates are well within the canonical range of luminosity densities necessary for reionization of the universe at this epoch by star-forming galaxies.