Browsing by Author "Mei, S."

Now showing 1 - 13 of 13
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    Hubble Space Telescope ACS Multiband Coronagraphic Imaging of the Debris Disk around β Pictoris
    (2006) Golimowski, D. A.; Ardila, D. R.; Krist, J. E.; Clampin, M.; Ford, H. C.; Illingworth, G. D.; Bartko, F.; Benitez, N.; Blakeslee, J. P.; Bouwens, R. J.; Bradley, L. D.; Broadhurst, T. J.; Brown, R. A.; Burrows, C. J.; Cheng, E. S.; Cross, N. J. G.; Demarco, R.; Feldman, P. D.; Franx, M.; Goto, T.; Gronwall, C.; Hartig, G. F.; Holden, B. P.; Homeier, N. L.; Infante, L.; Jee, M. J.; Kimble, R. A.; Lesser, M. P.; Martel, A. R.; Mei, S.; Menanteau, F.; Meurer, G. R.; Miley, G. K.; Motta, V.; Postman, M.; Rosati, P.; Sirianni, M.; Sparks, W. B.; Tran, H. D.; Tsvetanov, Z. I.; White, R. L.; Zheng, W.; Zirm, A. W.
    We present F435W(B), F606W (broad V), and F814W(broad I) coronagraphic images of the debris disk around beta Pictoris obtained with the Hubble Space Telescope's Advanced Camera for Surveys. These images provide the most photometrically accurate and morphologically detailed views of the disk between 30 and 300 AU from the star ever recorded in scattered light. We confirm that the previously reported warp in the inner disk is a distinct secondary disk inclined by similar to 5 degrees from the main disk. The projected spine of the secondary disk coincides with the isophotal inflections, or "butterfly asymmetry,'' previously seen at large distances from the star. We also confirm that the opposing extensions of the main disk have different position angles, but we find that this "wing-tilt asymmetry'' is centered on the star rather than offset from it, as previously reported. The main disk's northeast extension is linear from 80 to 250 AU, but the southwest extension is distinctly bowed with an amplitude of similar to 1 AU over the same region. Both extensions of the secondary disk appear linear, but not collinear, from 80 to 150 AU. Within similar to 120 AU of the star, the main disk is similar to 50% thinner than previously reported. The surface brightness profiles along the spine of the main disk are fitted with four distinct radial power laws between 40 and 250 AU, while those of the secondary disk between 80 and 150 AU are fitted with single power laws. These discrepancies suggest that the two disks have different grain compositions or size distributions. The F606W/F435W and F814W/F435W flux ratios of the composite disk are nonuniform and asymmetric about both projected axes of the disk. The disk's northwest region appears 20%-30% redder than its southeast region, which is inconsistent with the notion that forward scattering from the nearer northwest side of the disk should diminish with increasing wavelength. Within similar to 120 AU, the m(F435W)-m(F606W) and m(F435W)-m(F814W) colors along the spine of the main disk are similar to 10% and similar to 20% redder, respectively, than those of beta Pic. These colors increasingly redden beyond similar to 120 AU, becoming 25% and 40% redder, respectively, than the star at 250 AU. These measurements overrule previous determinations that the disk is composed of neutrally scattering grains. The change in color gradient at similar to 120 AU nearly coincides with the prominent inflection in the surface brightness profile at similar to 115 AU and the expected water-ice sublimation boundary. We compare the observed red colors within similar to 120 AU with the simulated colors of nonicy grains having a radial number density alpha r(-3) and different compositions, porosities, and minimum grain sizes. The observed colors are consistent with those of compact or moderately porous grains of astronomical silicate and/or graphite with sizes greater than or similar to 0.15-0.20 mu m, but the colors are inconsistent with the blue colors expected from grains with porosities greater than or similar to 90%. The increasingly red colors beyond the ice sublimation zone may indicate the condensation of icy mantles on the refractory grains, or they may reflect an increasing minimum grain size caused by the cessation of cometary activity.
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    Larger sizes of massive quiescent early-type galaxies in clusters than in the field at 0.8 < z < 1.5
    (2014) Delaye, L.; Huertas-Company, M.; Mei, S.; Lidman, C.; Licitra, R.; Newman, A.; Raichoor, A.; Shankar, F.; Barrientos, Luis Felipe; Bernardi, M.; Cerulo, P.; Couch, W.; Demarco, R.; Muñoz, R.; Sánchez-Janssen, R.; Tanaka, M.
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    Next Generation Virgo Cluster Survey. XXI. The Weak Lensing Masses of the CFHTLS and NGVS RedGOLD Galaxy Clusters and Calibration of the Optical Richness
    (2017) Parroni, C.; Mei, S.; Erben, T.; Van Waerbeke, L.; Raichoor, A.; Ford, J.; Licitra, R.; Meneghetti, M.; Hildebrandt, H.; Puzia, Thomas H.; Miller, L.; Cote, P.; Covone, G.; Cuillandre, J.; Duc, P.; Ferrarese, L.; Gwyn, S.
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    The accelerated build-up of the red sequence in high-redshift galaxy clusters
    (2016) Cerulo, P.; Couch, W. J.; Lidman, C.; Demarco, R.; Huertas Company, M.; Mei, S.; Sánchez Jansse, R.; Barrientos, Luis Felipe; Muñoz Soria, Roberto
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    The morphological transformation of red sequence galaxies in clusters since z ~ 1
    (2017) Cerulo, P.; Couch, W. J.; Lidman, C.; Demarco, R.; Huertas Company, M.; Mei, S.; Sánchez Janssen, R.; Barrientos, Luis Felipe; Muñoz, R.
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    The Morphology-Density Relation in z ~ 1 Clusters
    (2005) Postman, M.; Franx, M.; Cross, N.J.G.; Holden, B.; Ford, H.C.; Illingworth, G.D.; Goto, T.; Demarco, R.; Rosati, P.; Blakeslee, JP; Tran, K.V.; Benítez, N.; Clampin, M.; Hartig, G.F.; Homeier, N.; Ardila, D.R.; Bartko, F.; Bouwens, R.J.; Bradley, L.D.; Broadhurst, T.J.; Brown, R.A.; Burrows, C.J.; Cheng, E.S.; Feldman, P.D.; Golimowski, D.A.; Gronwall, C.; Infante, L.; Kimble, R.A.; Krist, J.E.; Lesser, M.P.; Martel, A.R.; Mei, S.; Menanteau, F.; Meurer, G.R.; Miley, G.K.; Motta, V.; Sirianni, M.; Sparks, W.B.; Tran, H.D.; Tsvetanov, Z.I.; White, R.L.; Zheng, W.
    We measure the morphology-density relation (MDR) and morphology-radius relation (MRR) for galaxies in seven z similar to 1 clusters that have been observed with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope. Simulations and independent comparisons of our visually derived morphologies indicate that ACS allows one to distinguish between E, S0, and spiral morphologies down to z(850) = 24, corresponding to L/L* 0.21 and 0.30 at z = 0.83 and 1.24, respectively. We adopt density and radius estimation methods that match those used at lower redshift in order to study the evolution of the MDR and MRR. We detect a change in the MDR between 0: 8 < z < 1.2 and that observed at z similar to 0, consistent with recent work; specifically, the growth in the bulge-dominated galaxy fraction, f(E+S0), with increasing density proceeds less rapidly at z similar to 1 than it does at z similar to 0. At z similar to 1 and Sigma >= 500 galaxies Mpc(-2), we find < f(E+S0)> = 0.72 +/- 0.10. At z similar to 0, an E + S0 population fraction of this magnitude occurs at densities about 5 times smaller. The evolution in the MDR is confined to densities Sigma greater than or similar to 40 galaxies Mpc(-2) and appears to be primarily due to a deficit of S0 galaxies and an excess of Sp+Irr galaxies relative to the local galaxy population. The f(E)-density relation exhibits no significant evolution between z = 1 and 0. We find mild evidence to suggest that the MDR is dependent on the bolometric X-ray luminosity of the intracluster medium. Implications for the evolution of the disk galaxy population in dense regions are discussed in the context of these observations.
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    The Next Generation Virgo Cluster Survey (NGVS). XIV. The Discovery of Low-mass Galaxies and a New Galaxy Catalog in the Core of the Virgo Cluster
    (2020) Ferrarese, L.; Côté, P.; Macarthur, L. A.; Durrell, P. R.; Gwyn, S. D. J.; Duc, P. A.; Sánchez Janssen, R.; Jordán Colzani, Andrés Cristóbal; Puzia, Thomas H.; Santos, M.; Blakeslee, J. P.; Boselli, A.; Boyer, F.; Cantiello, M.; Courteau, S.; Cuillandre, J. C.; Emsellem, E.; Erben, T.; Gavazzi, G.; Guhathakurta, P.; Huertas Company, M.; Lançon, A.; Liu, C.; Mei, S.; Mihos, J. C.; Peng, E. W.; Roediger, J.; Schade, D.; Taylor, J. E.; Toloba, E.; Zhang, H.
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    The next generation virgo cluster survey. XV. The photometric redshift estimation for background sources
    (2014) Raichoor, A.; Mei, S.; Erben, T.; Hildebrandt, H.; Huertas Company, M.; Ilbert, O.; Licitra, R.; Ball, N.M.; Muñoz Soria, Roberto; Puzia, Thomas H.
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    The Next Generation Virgo Cluster Survey. XXXIV. Ultracompact Dwarf Galaxies in the Virgo Cluster
    (2020) Liu, C. Z.; Cote, P.; Peng, E. W.; Roediger, J.; Zhang, H. X.; Ferrarese, L.; Sánchez Janssen, R.; Guhathakurta, P.; Yang, X. H.; Puzia, Thomas H.; Jing, Y. P.; Alamo Martínez, K.; Blakeslee, J. P.; Boselli, A.; Cuilandre, J. C.; Duc, P. A.; Durrell, P.; Gwyn, S.; Jordán Colzani, Andrés Cristóbal; Ko, Y.; Lancon, A.; Lim, S.; Longobardi, A.; Mei, S.; Mihos, J. C.; Munoz, R.; Powalka, M.; Spengler, C.; Toloba, E.