116 results on '"Gerke, Brian"'
Search Results
102. The DEEP2 Galaxy Redshift Survey: Evolution of Close Galaxy Pairs and Major-Merger Rates up to z ~ 1.2
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Lin, Lihwai, primary, Koo, David C., additional, Willmer, Christopher N. A., additional, Patton, David R., additional, Conselice, Christopher J., additional, Yan, Renbin, additional, Coil, Alison L., additional, Cooper, Michael C., additional, Davis, Marc, additional, Faber, S. M., additional, Gerke, Brian F., additional, Guhathakurta, Puragra, additional, and Newman, Jeffrey A., additional
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- 2004
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103. Quantum coherent dynamics of molecules: A simple scenario for ultrafast photoisomerization
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Aalberts, Daniel P., primary, du Croo de Jongh, M. S. L., additional, Gerke, Brian F., additional, and Saarloos, Wim van, additional
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- 2000
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104. Dependence of galaxy quenching on halo mass and distance from its centre.
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Woo, Joanna, Dekel, Avishai, Faber, S. M., Noeske, Kai, Koo, David C., Gerke, Brian F., Cooper, Michael C., Salim, Samir, Dutton, Aaron A., Newman, Jeffrey, Weiner, Benjamin J., Bundy, Kevin, Willmer, Christopher N. A., Davis, Marc, and Yan, Renbin
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STAR formation ,GALACTIC halos ,ATOMIC mass ,STAR colors ,GALACTIC evolution - Abstract
We study the dependence of star formation quenching on galaxy mass and environment, in the Sloan Digital Sky Survey (SDSS; z ∼ 0.1) and the All-Wavelength Extended Groth Strip International Survey (AEGIS; z ∼ 1). It is crucial that we define quenching by low star formation rate rather than by red colour, given that one-third of the red galaxies are star forming. We address stellar mass M*, halo mass Mh, density over the nearest N neighbours δN and distance to the halo centre D. The fraction of quenched galaxies appears more strongly correlated with Mh at fixed M* than with M* at fixed Mh, while for satellites quenching also depends on D. We present the M*–Mh relation for centrals at z ∼ 1. At z ∼ 1, the dependence of quenching on M* at fixed Mh is somewhat more pronounced than at z ∼ 0, but the quenched fraction is low (10 per cent) and the haloes are less massive. For satellites, M*-dependent quenching is noticeable at high D, suggesting a quenching dependence on subhalo mass for recently captured satellites. At small D, where satellites likely fell in more than a few Gyr ago, quenching strongly depends on Mh and not on M*. The Mh dependence of quenching is consistent with theoretical wisdom where virial shock heating in massive haloes shuts down accretion and triggers ram-pressure stripping, causing quenching. The interpretation of δN is complicated by the fact that it depends on the number of observed group members compared to N, motivating the use of D as a better measure of local environment. [ABSTRACT FROM AUTHOR]
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- 2013
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105. The DEEP2 Galaxy Redshift Survey: environments of post-starburst galaxies at z∼ 0.1 and ∼0.8.
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Yan, Renbin, Newman, Jeffrey A., Faber, S. M., Coil, Alison L., Cooper, Michael C., Davis, Marc, Weiner, Benjamin J., Gerke, Brian F., and Koo, David C.
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STARBURSTS ,STAR formation ,STAR clusters ,REDSHIFT ,EARLY stars - Abstract
Post-starburst (also known as K+A) galaxies exhibit spectroscopic signatures indicating that their star formation was recently quenched; they are candidates for galaxies in transition from a star-forming phase to a passively evolving phase. We have spectroscopically identified large samples of post-starburst galaxies both in the Sloan Digital Sky Survey (SDSS) at and in the DEEP2 Galaxy Redshift Survey at , using a uniform and robust selection method based on a cut in Hβ line emission rather than the more problematic [O ii]λ3727. Based on measurements of the overdensity of galaxies around each object, we find that post-starburst galaxies brighter than at low redshift have a similar, statistically indistinguishable environment distribution as blue galaxies, preferring underdense environments, but dramatically different from that of red galaxies. However, at higher- z, the environment distribution of post-starburst galaxies is more similar to red galaxies than to blue galaxies. We conclude that the quenching of star formation and the build-up of the red sequence through the K+A phase is happening in relatively overdense environments at but in relatively underdense environments at . Although the relative environments where quenching occurs are decreasing with time, the corresponding absolute environment may have stayed the same along with the quenching mechanisms, because the mean absolute environments of all galaxies has to grow with time. In addition, we do not find any significant dependence on luminosity in the environment distribution of K+As. The existence of a large K+A population in the field at both redshifts indicates that cluster-specific mechanisms cannot be the dominant route by which these galaxies are formed. Our work also demonstrates that studying post-starburst–environment relations by measuring the K+A fraction in different environments, as is the common practice, is highly non-robust; modest changes in the comparison population used to define the fraction can drastically alter conclusions. Statistical comparisons of the overall environment distributions of different populations are much better behaved. [ABSTRACT FROM AUTHOR]
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- 2009
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106. The DEEP2 Galaxy Redshift Survey: the role of galaxy environment in the cosmic star formation history.
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Cooper, Michael C., Newman, Jeffrey A., Weiner, Benjamin J., Yan, Renbin, Willmer, Christopher N. A., Bundy, Kevin, Coil, Alison L., Conselice, Christopher J., Davis, Marc, Faber, S. M., Gerke, Brian F., Guhathakurta, Puragra, Koo, David C., and Noeske, Kai G.
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GALAXIES ,REDSHIFT ,ASTROPHYSICS ,METAPHYSICAL cosmology ,DOPPLER effect - Abstract
Using galaxy samples drawn from the Sloan Digital Sky Survey and the DEEP2 Galaxy Redshift Survey, we study the relationship between star formation and environment at and 1. We estimate the total star formation rate (SFR) and specific star formation rate (sSFR) for each galaxy according to the measured [O ii]λ 3727 Å nebular line luminosity, corrected using empirical calibrations to match more robust SFR indicators. Echoing previous results, we find that in the local Universe star formation depends on environment such that galaxies in regions of higher overdensity, on average, have lower SFRs and longer star formation time-scales than their counterparts in lower density regions. At , we show that the relationship between sSFR and environment mirrors that found locally. However, we discover that the relationship between total SFR and overdensity at is inverted relative to the local relation. This observed evolution in the SFR–density relation is driven, in part, by a population of bright, blue galaxies in dense environments at . This population, which lacks a counterpart at , is thought to evolve into members of the red sequence from to ∼0. Finally, we conclude that environment does not play a dominant role in the cosmic star formation history at : the dependence of the mean galaxy SFR on local galaxy density at constant redshift is small compared to the decline in the global SFR space density over the last 7 Gyr. [ABSTRACT FROM AUTHOR]
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- 2008
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107. The DEEP2 Galaxy Redshift Survey: the relationship between galaxy properties and environment at z∼ 1.
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Cooper, Michael C., Newman, Jeffrey A., Croton, Darren J., Weiner, Benjamin J., Willmer, Christopher N. A., Gerke, Brian F., Madgwick, Darren S., Faber, S. M., Davis, Marc, Coil, Alison L., Finkbeiner, Douglas P., Guhathakurta, Puragra, and Koo, David C.
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REDSHIFT ,GALACTIC evolution ,GALAXY formation ,GALAXY clusters ,STAR formation ,STAR clusters ,EARLY stars - Abstract
We study the mean environment of galaxies in the DEEP2 Galaxy Redshift Survey as a function of rest-frame colour, luminosity, and [O ii] 3727 Å equivalent width. The local galaxy overdensity for >14 000 galaxies at is estimated using the projected third-nearest-neighbour surface density. Of the galaxy properties studied, mean environment is found to depend most strongly on galaxy colour; all major features of the correlation between mean overdensity and rest-frame colour observed in the local universe were already in place at . In contrast to local results, we find a substantial slope in the mean dependence of environment on luminosity for blue, star forming galaxies at , with brighter blue galaxies being found on average in regions of greater overdensity. We discuss the roles of galaxy clusters and groups in establishing the observed correlations between environment and galaxy properties at high redshift, and we also explore the evidence for a ‘downsizing of quenching’ from to ∼0. Our results add weight to existing evidence that the mechanism(s) that result in star formation quenching are efficient in group environments as well as clusters. This work is the first of its kind at high redshift and represents the first in a series of papers addressing the role of environment in galaxy formation at . [ABSTRACT FROM AUTHOR]
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- 2006
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108. The DEEP2 Galaxy Redshift Survey: Clustering of Groups and Group Galaxies at z ~ 1.
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Coil, Alison L., Gerke, Brian F., Newman, Jeffrey A., Ma, Chung-Pei, Yan, Renbin, Cooper, Michael C., Davis, Marc, Faber, S. M., Guhathakurta, Puragra, and Koo, David C.
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- 2006
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109. The DEEP2 Galaxy Redshift Survey: Color and Luminosity Dependence of Galaxy Clustering at <IMG SRC="eq-00001.gif" ALT="z\sim 1"/> z ? 1
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Coil, Alison L., Newman, Jeffrey A., Croton, Darren, Cooper, Michael C., Davis, Marc, Gerke, Brian F., Koo, David C., Padmanabhan, Nikhil, Wechsler, Risa H., and Weiner, Benjamin J.
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We present measurements of the color and luminosity dependence of galaxy clustering at z [?] 1 in the DEEP2 Galaxy Redshift Survey. Using volume-limited subsamples in bins of both color and luminosity, we find the following: (1) The clustering dependence is much stronger with color than with luminosity and is as strong with color at z [?] 1 as is found locally. We find no dependence of the clustering amplitude on color for galaxies on the red sequence, but a significant dependence on color for galaxies within the blue cloud. (2) For galaxies in the range L/L* [?] 0.7-2, a stronger large-scale luminosity dependence is seen for all galaxies than is seen for red and blue galaxies separately. The small-scale clustering amplitude depends significantly on luminosity for blue galaxies, with brighter samples having a stronger rise on scales rp < 0.5 h[?]1 Mpc. (3) Redder galaxies exhibit stronger small-scale redshift-space distortions ("fingers of god"), and both red and blue populations show large-scale distortions in x (rp,p) due to coherent infall. (4) While the clustering length, r0, increases smoothly with galaxy color (in narrow bins), its power-law exponent, g, exhibits a sharp jump from the blue cloud to the red sequence. The intermediate-color "green" galaxy population likely includes transitional galaxies moving from the blue cloud to the red sequence; on large scales green galaxies are as clustered as red galaxies but show infall kinematics and a small-scale correlation slope akin to the blue galaxy population. (5) We compare our results to a semianalytic galaxy formation model applied to the Millennium Run simulation. Differences between the data and the model suggest that in the model star formation is shut down too efficiently in satellite galaxies.
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- 2008
110. Evolution in the Halo Masses of Isolated Galaxies between z ~ 1 and z ~ 0: From DEEP2 to SDSS
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Conroy, Charlie, Prada, Francisco, Newman, Jeffrey A., Croton, Darren, Coil, Alison L., Conselice, Christopher J., Cooper, Michael C., Davis, Marc, Gerke, Brian F., Guhathakurta, Puragra, Klypin, Anatoly, Koo, David C., and Yan, Renbin
- Abstract
We measure the evolution in the virial mass-to-light ratio (M200/LB) and virial-to-stellar mass ratio (M200/M*) for isolated ~L* galaxies between z ~ 1 and z ~ 0 by combining data from the DEEP2 Galaxy Redshift Survey and the Sloan Digital Sky Survey. Utilizing the motions of satellite galaxies around isolated galaxies, we measure line-of-sight velocity dispersions and derive dark matter halo virial masses for these host galaxies. At both epochs the velocity dispersion of satellites correlates with host galaxy stellar mass, s [?] Mimg1.gif, while the relation between satellite velocity dispersion and host galaxy B-band luminosity may grow somewhat shallower from s [?] Limg2.gif at z ~ 1 to s [?] Limg3.gif at z ~ 0. The evolution in M200/M* from z ~ 1 to z ~ 0 displays a bimodality insofar as host galaxies with stellar mass below M* ~ 1011 h-1 M maintain a constant ratio (the intrinsic increase is constrained to a factor of 1.1 +- 0.5) while host galaxies above M* ~ 1011 h-1 M experience a factor of 3.3 +- 2.2 increase in their virial-to-stellar mass ratio. This result can be easily understood if galaxies below this stellar mass scale continue to form stars while star formation in galaxies above this scale is quenched and the dark matter halos of galaxies both above and below this scale grow in accordance with LCDM cosmological simulations. Host galaxies that are red in U - B color have larger satellite dispersions and hence reside on average in more massive halos than blue galaxies at both z ~ 1 and z ~ 0. The satellite population of host galaxies varies little between these epochs. The redshift and host galaxy stellar mass dependence of M200/M* agrees qualitatively with the Millennium Run semianalytic model of galaxy formation.
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- 2007
111. The DEEP2 Galaxy Redshift Survey: Probing the Evolution of Dark Matter Halos around Isolated Galaxies from z ~ 1 to z ~ 0
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Conroy, Charlie, Newman, Jeffrey A., Davis, Marc, Coil, Alison L., Yan, Renbin, Cooper, Michael C., Gerke, Brian F., and Koo, David C.
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Using the first 25% of the DEEP2 Redshift Survey data, we probe the line-of-sight velocity dispersion profile for isolated galaxies with absolute B-band magnitude -22 < MB - 5 log(h) < -21 at z = 0.7-1.0, using satellite galaxies as luminous tracers of the underlying velocity distribution. Measuring the velocity dispersion beyond a galactocentric radius of ~200 h-1 kpc (physical) permits us to determine the total mass, including dark matter, around these bright galaxies. Tests with mock catalogs based on N-body simulations indicate that this mass measurement method is robust to selection effects. We find a line-of-sight velocity dispersion (slos) of 162img1.gif km s-1 at ~110 h-1 kpc, 136img2.gif km s-1 at ~230 h-1 kpc, and 150img3.gif km s-1 at ~320 h-1 kpc. Assuming an NFW model for the dark matter density profile, this corresponds to a mass within r200 of M200 = 5.5img4.gif x 1012 h-1 M for our sample of satellite hosts with mean luminosity ~2.5L*. Roughly ~60% of these host galaxies have early-type spectra and are red in rest-frame (U - B) color, consistent with the overall DEEP2 sample in the same luminosity and redshift range. The halo mass determined for DEEP2 host galaxies is consistent with that measured in the Sloan Digital Sky Survey for host galaxies within a similar luminosity range relative to Mimg5.gif. This comparison is insensitive to the assumed halo mass profile and implies an increase in the dynamical mass-to-light ratio (M200/LB) of isolated galaxies that host satellites by a factor of ~2.5 from z ~ 1 to z ~ 0. Our results can be used to constrain the halo occupation distribution and the conditional luminosity function used to populate dark matter halos with galaxies. In particular, our results are consistent with scenarios in which galaxies populate dark matter halos similarly from z ~ 0 to z ~ 1, except for ~1 mag of evolution in the luminosity of all galaxies. With the full DEEP2 sample, it will be possible to extend this analysis to multiple luminosity or color bins.
- Published
- 2005
112. The DEEP2 Galaxy Redshift Survey: The Evolution of Void Statistics from z ~ 1 to z ~ 0
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Conroy, Charlie, Coil, Alison L., White, Martin, Newman, Jeffrey A., Yan, Renbin, Cooper, Michael C., Gerke, Brian F., Davis, Marc, and Koo, David C.
- Abstract
We present measurements of the void probability function (VPF) at z ~ 1 using data from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey and its evolution to z ~ 0 using data from the Sloan Digital Sky Survey (SDSS). We measure the VPF as a function of galaxy color and luminosity in both surveys and find that it mimics trends displayed in the two-point correlation function, x: namely, that samples of brighter, red galaxies have larger voids (i.e., are more strongly clustered) than fainter, blue galaxies. We also clearly detect evolution in the VPF with cosmic time, with voids being larger in comoving units at z ~ 0. We find that the reduced VPF matches the predictions of a "negative binomial" model for galaxies of all colors, luminosities, and redshifts studied. This model lacks a physical motivation but produces a simple analytic prediction for sources of any number density and integrated two-point correlation function, img1.gif. This implies that differences in the VPF across different galaxy populations are consistent with being due entirely to differences in the population number density and img1.gif. We compare the VPF at z ~ 1 to N-body LCDM simulations and find good agreement between the DEEP2 data and mock galaxy catalogs. Interestingly, we find that the dark matter particle reduced VPF follows the physically motivated "thermodynamic" model, while the dark matter halo reduced VPF more closely follows the negative binomial model. The robust result that all galaxy populations follow the negative binomial model appears to be due primarily to the clustering of dark matter halos. The reduced VPF is insensitive to changes in the parameters of the halo occupation distribution, in the sense that halo models with the same img1.gif will produce the same VPF. For the wide range of galaxies studied, the VPF therefore does not appear to provide useful constraints on galaxy evolution models that cannot be gleaned from studies of img1.gif alone.
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- 2005
113. The DEEP2 Galaxy Redshift Survey: Spectral Classification of Galaxies at z ? 1
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Madgwick, Darren S., Coil, Alison L., Conselice, Christopher J., Cooper, Michael C., Davis, Marc, Ellis, Richard S., Faber, Sandy M., Finkbeiner, Douglas P., Gerke, Brian, Guhathakurta, Puragra, Kaiser, Nick, Koo, David C., Newman, Jeffrey A., Phillips, Andrew C., Steidel, Charles C., Weiner, Benjamin J., A, Christopher N., DEEP, The, and Survey, 2
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We present a principal component analysis (PCA)-based spectral classification, e, for the first 5600 galaxies observed in the DEEP2 Redshift Survey. This parameter provides a very pronounced separation between absorption- and emission-dominated galaxy spectra--corresponding to passively evolving and actively star-forming galaxies in the survey, respectively. In addition it is shown that, despite the high resolution of the observed spectra, this parameter alone can be used to quite accurately reconstruct any given galaxy spectrum, suggesting there are not many "degrees of freedom" in the observed spectra of this galaxy population. It is argued that this form of classification, e, will be particularly valuable in making future comparisons between high- and low-redshift galaxy surveys for which very large spectroscopic samples are now readily available, particularly when used in conjunction with high-resolution spectral synthesis models, which will be made public in the near future. We also discuss the relative advantages of this approach to distant galaxy classification compared to other methods such as colors and morphologies. Finally, we compare the classification derived here with that adopted for the 2dF Galaxy Redshift Survey and in so doing show that the two systems are very similar. This will be particularly useful in subsequent analyses when making comparisons between results from each of these surveys to study evolution in the galaxy populations and large-scale structure.
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- 2003
114. The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts
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Newman, Jeffrey A., Cooper, Michael C., Davis, Marc, Faber, S. M., Coil, Alison L., Guhathakurta, Puragra, Koo, David C., Phillips, Andrew C., Conroy, Charlie, Dutton, Aaron A., Finkbeiner, Douglas, Gerke, Brian F., Rosario, David J., Weiner, Benjamin J., Willmer, C. N. A., Yan, Renbin, Harker, Justin J., Kassin, Susan A., Konidaris, N. P., Lai, Kamson, Madgwick, Darren S., Noeske, K. G., Wirth, Gregory D., Connolly, A. J., Kaiser, N., Kirby, Evan N., Lemaux, Brian C., Lin, Lihwai, Lotz, Jennifer M., Luppino, G. A., Marinoni, C., Matthews, Daniel J., Metevier, Anne, and Schiavon, Ricardo P.
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cosmology: observations ,galaxies: distances and redshifts ,galaxies: evolution ,galaxies: fundamental parameters ,galaxies: high-redshift ,galaxies: statistics ,large-scale structure of universe ,methods: data analysis ,surveys - Abstract
We describe the design and data analysis of the DEEP2 Galaxy Redshift Survey, the densest and largest high-precision redshift survey of galaxies at z ~ 1 completed to date. The survey was designed to conduct a comprehensive census of massive galaxies, their properties, environments, and large-scale structure down to absolute magnitude MB = –20 at z ~ 1 via ~90 nights of observation on the Keck telescope. The survey covers an area of 2.8 deg2 divided into four separate fields observed to a limiting apparent magnitude of R AB = 24.1. Objects with z lesssim 0.7 are readily identifiable using BRI photometry and rejected in three of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted ~2.5 times more efficiently than in a purely magnitude-limited sample. Approximately 60% of eligible targets are chosen for spectroscopy, yielding nearly 53,000 spectra and more than 38,000 reliable redshift measurements. Most of the targets that fail to yield secure redshifts are blue objects that lie beyond z ~ 1.45, where the [O II] 3727 Å doublet lies in the infrared. The DEIMOS 1200 line mm–1 grating used for the survey delivers high spectral resolution (R ~ 6000), accurate and secure redshifts, and unique internal kinematic information. Extensive ancillary data are available in the DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into one of the richest multiwavelength regions on the sky. This paper is intended as a handbook for users of the DEEP2 Data Release 4, which includes all DEEP2 spectra and redshifts, as well as for the DEEP2 DEIMOS data reduction pipelines. Extensive details are provided on object selection, mask design, biases in target selection and redshift measurements, the spec2d two-dimensional data-reduction pipeline, the spec1d automated redshift pipeline, and the zspec visual redshift verification process, along with examples of instrumental signatures or other artifacts that in some cases remain after data reduction. Redshift errors and catastrophic failure rates are assessed through more than 2000 objects with duplicate observations. Sky subtraction is essentially photon-limited even under bright OH sky lines; we describe the strategies that permitted this, based on high image stability, accurate wavelength solutions, and powerful B-spline modeling methods. We also investigate the impact of targets that appear to be single objects in ground-based targeting imaging but prove to be composite in Hubble Space Telescope data; they constitute several percent of targets at z ~ 1, approaching ~5%-10% at z > 1.5. Summary data are given that demonstrate the superiority of DEEP2 over other deep high-precision redshift surveys at z ~ 1 in terms of redshift accuracy, sample number density, and amount of spectral information. We also provide an overview of the scientific highlights of the DEEP2 survey thus far., Astronomy
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- 2013
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115. THE VORONOI TESSELLATION CLUSTER FINDER IN 2+1 DIMENSIONS.
- Author
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Soares-Santos, Marcelle, de Carvalho, Reinaldo R., Annis, James, Gal, Roy R., La Barbera, Francesco, Lopes, Paulo A. A., Wechsler, Risa H., Busha, Michael T., and Gerke, Brian F.
- Published
- 2011
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116. The DEEP2 Galaxy Redshift Survey: Color and Luminosity Dependence of Galaxy Clustering at z ∼ 1.
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Coil, Alison L., Newman, Jeffrey A., Croton, Darren, Cooper, Michael C., Davis, Marc, Faber, S. M., Gerke, Brian F., Koo, David C., Padmanabhan, Nikhil, Wechsler, Risa H., and Weiner, Benjamin J.
- Published
- 2008
- Full Text
- View/download PDF
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