Early%20Results%20from%20the%20DEEP2%20Redshift%20Survey

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Early Results from the DEEP2 Redshift Survey
Benjamin Weiner (UCO/Lick Observatory) and the
DEEP collaboration
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DEEP 2 Survey Team

• UC Berkeley M. Davis, J. Newman, A. Coil, D.
  Madgwick, M. Cooper, B. Gerke, R. Yan, C. Conroy
• UC Santa Cruz S. Faber, D. Koo, P. Guhathakurta,
  A. Phillips, C. Willmer, R. Schiavon, N.
  Konidaris
• Caltech C. Steidel, R. Ellis, T.Treu, C.
  Conselice
• Others N. Kaiser, G. Wirth, A. Connolly, D.
  Finkbeiner,
• G. Luppino, P. Eisenhardt

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DEEP two redshift surveys
Deep Extragalactic Evolutionary Probe DEEP 1
redshift survey in fields with deep HST WFPC2
imaging Keck/LRIS, 625 galaxy redshifts in Groth
Strip DEEP 2 large scale survey targeting
galaxy properties and clustering at z
1 Keck/DEIMOS, goal 50,000 galaxy redshifts
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DEEP 2 a redshift survey at z 1
1 Hour Survey 1 hour exposures 4 fields, 3.5
square degrees magnitude limit R(AB) lt
24.1 65,000 targets, 50,000 galaxy
redshifts most at 0.7ltzlt1.5 90 Keck nights
over 3 years 3 Hour Survey deeper
exposures red (elliptical) galaxies probable
zgt1.5 galaxies - redshift failures from 1HS
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Redshift surveys background
Surveys probe distribution of galaxies Also
provide samples to study galaxy properties
Las Campanas Redshift Survey (Shectman et al 1996)
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DEEP2 compared to low- z surveys
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Studying galaxies at z1
Universe half its current age, Galaxies are
younger but still recognizable Spectral features
accessible to optical telescopes HST IR/optical
imaging corresponds to restframe red/blue
from HST WFPC2 Groth Strip
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DEEP2 target selection
Galaxies selected from CFHT 12K imaging,
R(AB)lt24.1 4 fields, each 0.5 x 2.0 deg (Groth
Strip 0.25 x 2.0 deg) Color- cut selection in 3
fields selects zgt0.7 galaxies in Groth Strip we
take everything. 2- pass and 4- pass mask
coverage
200 x 200 from BRI CFHT images
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DEEP2 spectroscopy
DEIMOS with 1200- line grating. 6500- 9200 A,
covers O II 3727 doublet at 0.7ltzlt1.5 Distinct
ive feature high resolution 1.0 slit,
resolution 1.5 A FWHM, O II well resolved 60
km/sec FW at z1, dispersion s 25 km/sec Can
measure internal kinematics rotation/dispersion,
galaxy masses
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DEIMOS spectrograph atKeck II Nasmyth focus
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Inside DEIMOS
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Spectra from DEIMOS lots of slits!
One-half of one mask. Each has 120- 150 slits,
average 5 long
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Reduced data through pipeline
cleaned, combined, sky subtracted
Pipeline developed from SDSS code (of Schlegel,
Finkbeiner, Burles) by UC Berkeley group
galaxy group, s 250 km/sec, at z1
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Redshift measurement and verification
Find candidate redshifts by automated chi-sq fit
to a set of templates Need to be checked by
humans GUI shows 1- D and 2- D data
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Progress so far
Instrument working well, pipeline in operation
Both in use by other Keck users 190/480 masks
observed, 40 complete 8,200 galaxy redshifts
checked and in catalog
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Redshift, color and magnitude
2700 galaxies in Groth Strip Large scale
structure walls Color bimodality - red/blue
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Photo- z color cut
Redshifts from Groth Strip verify color cut works
cleanly
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Redshift success and failure
Most of failures are faint blue galaxies Most of
these are presumably high z, z gt 1.5
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Space distribution
z0.4
z1.3
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Galaxy restframe color and luminosity
Blue/red separation No faint red Brighter blue
galaxies at high z Lose red galaxies to mag
cutoff
Extended Groth Strip
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Galaxy restframe color and luminosity
All fields lots more galaxies at zgt0.7
All fields (8000 galaxies)
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Blue luminosity function
Simplistic 1/Vmax on EGS data Evolution in blue
galaxies at bright end? Real calculations forthco
ming (Christopher Willmer et al)
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Red galaxies are the ones with bulges
DEEP 1 galaxies with HST imaging (fits by L.
Simard) Blue galaxies mostly exponential Red
galaxies more concentrated
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Red bulges are bright at z lt 1
DEEP 1 galaxies with HST imaging (fits by L.
Simard) Blue galaxies starforming, disky Red
galaxies brighter bulges
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COMBO- 17 photometric survey
Bell et al. 2003
Large area, 17 filters, photo- z Color
evolution in red sequence Mass buildup in red
galaxies?
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Color bimodality and evolution?
L model
Z model
Which is consistent with color and luminosity
evolution?
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Galaxy correlation functions
Alison Coil et al. 2003 submitted Clustering
measure quantified Red galaxies more
clustered Starforming galaxies less clustered
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Rotation curves
Michael Cooper (UC Berkeley)
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Integrated emission linewidths
Fit lines to 1- D extracted spectrum Kinematic
measurement even when spatially unresolved
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Linewidth- magnitude relation
3200 galaxies, z gt 0.65 0.65ltzlt0.8 slope
same as low- z, ZP offset Higher
redshifts zeropoint offset increases slope
flattens Bright galaxies with low dispersions
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Color- magnitude relation
At high z, bright galaxies had low
dispersions relative to low z TF rel Yet bright
galaxies are still redder - not pure
starbursts Note selection limit in high z bin
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Color- linewidth residual
Pretty flat but for highest z bin Redder
objects are brighter, and/or have lower
dispersion than predicted from TF
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O II line strength relations
Absolute strength
Equivalent width
Both increase with redshift
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O II luminosity function
Simple 1/Vmax weighting Signature of evolution
at bright end
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Velocity function (baby steps)
Like a luminosity function but counts number of
objects of given dispersion Simple 1/Vmax
weighting Suggestion of evolution at high mass
end - fewer high dispersion galaxies at high
redshift?
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Where we're going
Catching up to current data, and more data
coming including Palomar K-band photometry More
studies of galaxy properties and
environment Galaxy groups Cosmological models
and tests - counting halos, groups Confronting
galaxy evolution models Extended Groth Strip -
SIRTF, Galex, X- ray and radio data
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