Browsing by Author "Holden, BP"

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    Advanced camera for surveys observations of a strongly lensed arc in a field elliptical galaxy
    (2004) Blakeslee, JP; Zekser, KC; Benítez, N; Franx, M; White, RL; Ford, HC; Bouwens, RJ; Infante, L; Cross, NJ; Hertling, G; Holden, BP; Illingworth, GD; Motta, V; Menanteau, F; Meurer, GR; Postman, M; Rosati, P; Zheng, W
    We report the discovery of a strongly lensed arc system around a field elliptical galaxy in Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) images of a parallel field observed during NICMOS observations of the HST Ultra Deep Field. The ACS parallel data comprise deep imaging in the F435W, F606W, F775W, and F850LP bandpasses. The main arc is at a radius of 1."6 from the galaxy center and subtends about 120degrees. Spectroscopic follow-up at Magellan Observatory yields a redshift z = 0.6174 for the lensing galaxy, and we photometrically estimate z(phot) = 2.4 +/- 0.3 for the arc. We also identify a likely counterarc at a radius of 0."6 that shows structure similar to that seen in the main arc. We model this system and find a good fit to an elliptical isothermal potential of velocity dispersion a sigma approximate to 300 km s(-1), the value expected from the fundamental plane, and some external shear. Several other galaxies in the field have colors similar to the lensing galaxy and likely make up a small group.
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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.