The Growth of LSS in a Dark Energy Dominated Universe A Century of Cosmology

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The Growth of LSS in a Dark Energy Dominated
UniverseA Century of Cosmology
Marc Davis UC Berkeley
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The DEEP2 Collaboration
The DEEP2 Galaxy Redshift Survey used the DEIMOS
spectrograph at the Keck II telescope to study
both galaxy properties and large-scale structure
at z1.

• Other Institutions
• J. Newman (LBNL)
• A. Coil (Arizona)
• C. Willmer (Arizona)
• B. Weiner (Arizona)
• R. Schiavon (UVA)
• C. Conroy (Princeton)
• N. Kaiser (Hawaii)
• D. Finkbeiner
• (Harvard)
• A. Connolly (Pitt.)

• U.C. Berkeley
• M. Davis (PI)
• D. Croton
• M. Cooper
• B. Gerke
• R. Yan
• U.C. Santa Cruz
• S. Faber (Co-PI)
• D. Koo
• P. Guhathakurta

U.C. Santa Cruz D. Phillips S. Kassin K. Noeske
A. Metevier L. Lin N. Konidaris G. Graves J.
Harker
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DEEP2 has been made possible by DEIMOS, a new
instrument on Keck II

• DEIMOS
• PI Faber
• wide-field multiplexing (up to 160 slitlets over
  a 16x4 field)
• high resolution (R5000)
• spectral range (2600 Å at highest resolution)
• CCD array of 8k x 8k

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DEEP2 pre-selects high-z galaxies using observed
colors
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DEEP2 mask selection

• Targeted galaxies are enclosed with white curves
• Solid slits are objects selected on a given mask.
  
• dotted and dashed lines are galaxies from
  neighboring masks.

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DEEP2 slitmask spectroscopy
l
position
Using custom-milled slitmasks with DEIMOS we
obtained spectra of 150 targets at a time. A
total of 400 slitmasks was required for the
survey we tilted slits up to 30 degrees to
obtain rotation curves.
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AEGIS the All-wavelength Extended Groth Strip
International Survey
Spitzer MIPS, IRAC
DEEP2 spectra and Caltech/JPL Ks imaging
HST/ACS V,I (Cycle 13)
Plus VLA (6 21 cm), SCUBA, etc.
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X-ray analysis - detection and photometry

• P.Nandra et al.
• Each square has integration time of 200 ksec
• Source selection and photometry by own method
• Elliptical shaped PSFs
• All data will be released in August, 2007

1.6 Ms
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Comparison with Other Surveys

• DEEP2 -- comparable in size and density to
  previous generation local redshift surveys
• gt50 times larger than previous surveys at
  z0.3-1.

DEEP2 is similar to LCRS in sample size but at
z1 - with a very different geometry
20?80?1000 h-3 Mpc3 per field (LCDM)
SDSS
2dF
LCRS
z0 z1
DEEP2
PSCZ
CFA SSRS
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A Redshift Survey at z1

• 3 sq. degrees
• 4 fields (0.5o x lt2o)
• 80 Keck nights, one-hour exposures to RAB24.1
• primarily z0.75-1.4 (pre-selected using BRI
  photometry)
• 46,585 unique redshifts, error 30 km/s
• 5106 h-3 Mpc3
• 1200 l/mm 6500-9200 Å
• 1.0 slit FWHM? 68 km/s
• z0.7-1.4 spans lookback time 6.0 - 8.0 Gyr ago
• Within DEEP2 we are surveying 2.5 Gyr or 20
  of the history of the Universe, and SDSS/2dF
  comparisons give 3x this baseline

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Redshift Distribution of DEEP2 Survey
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DEEP2 Status Update

• DEEP2 began observations in July 2002.
• Observations are now gt95 finished, with gt49k
  spectra in hand and 3 of 4 fields completed.
• Follow-up observations have begun.
• ALL the data is already public
• http//deep.berkeley.edu/DR3
• The catalog and 2d spectra is all available, and
  others are releasing Chandra, Spitzer, HST, .

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Cluster abundance depends on cosmology
Evrard et al. 02
Hubble volume simulations
Brian F. Gerke
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z1.0
z0.75
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Redshift Maps in 4 Fields z0.7-1.3
Cone diagram of 1/12 of the full DEEP2 sample
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Galaxy groups in DEEP2

• Overdensities identified in redshift space.
• Use the VDM algorithm of Marinoni et al. (2002).

• Group in early DEEP2 data s250 km/sec

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DEEP2 Group Catalog
Groups with ?gt350 km/s
Shown are groups for 3 fields --length of
ellipse proportional to velocity dispersion
Gerke et al. 2005, astro-ph/0410721
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Looking for DEEP2 groups in the X-ray

• 200 ks Chandra observation in the Extended Groth
  Strip (1/8 of total coverage), with positions of
  7 DEEP2 groups superimposed (2 lt N lt 7, ? gt 300
  km/s)
• T. Fang et al, 2006, in press

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Real Groups/Mock Groups
galaxies shown in 3 projections
x-r redshift plot
y-r redshift plot
Real or Mock???
X-y projected on sky
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Why search for groups in DEEP2?

• Apparent abundance of groups dN(s,z)/dzds?
• Provides a useful test of dark energy eq. of
  state (Newman et al, 2002)

• differences in the volume element varies by 3x
  between w0 and w-1
• For groups of modest-mass, the evolution of
  dispersion is 2nd order

• Heavy black curve is ?T.3 DEIMOS took 7 years
  to build at time of designing science expt. ?T
  was still undetermined, and DE was not discussed.

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Size of the Universe versus w
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Abundance versus Redshift
Gerke etal 2008
Simulated Data!!
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Measured dispersion with galaxies compared to
reality-- tremendous scatter!
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Dispersion with galaxies
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We can reconstruct the quantity we need with the
VDM

• We want to measure N(s, z) to constrain
  cosmology.
• Tests on the mock catalogs indicate that we can
  measure N(s,z) in DEEP2 accurately for sgt350
  km/s.

Brian F. Gerke
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Projected constraints
Computed with DM halos in simulated DEEP2 and 2dF
light cones, constructed from the Millennium
Run. In each panel, the suppressed parameter is
held fixed.
input cosmology
Brian F. Gerke
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DEEP2 Cluster Counts

• DEEP2 survey counted 300 groups
• Velocity dispersion measured in each case
• Counts of N(?, z) is a strong test of w
• Have not got mock catalogs with the evolving
  color selection, making it difficult to proceed
• B. Gerke will have results out soon

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Measuring Kaiser infall in ?(rp,?)
Coil et al, 2008

• The blue galaxies show fully developed coherent
  infall pattern on scales gt5 Mpc, as expected.
• The red galaxies have very extended fingers of
  god, as expected.

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Kaiser infall, MOCKS
Coil et al, 2008
Millenium mocks, not a bad approximation
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Conclusions on DEEP2

• DEEP2 observations are gt99 done
• Work not yet published is study of galaxy
  clustering
• DR3 has occurred this August
  http//deep.berkeley.edu/DR3
• AEGIS ApJL special issue
• Way too many new results to cover in one talk!

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We are beginning to measure w
Constraints of 314 groups Plot does not use
redshift information Furthermore, we are still
checking systematics!!
Gerke et al. 2005
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Velocity bias and N(s)

• A degenerate parameter is the velocity bias,
  bv. (factor by which the velocity dispersion of
  galaxies in a cluster differs from the dark
  matter dispersion. Some simulations currently
  favor bv1.1, others 0.9.)
• Degeneracy between
• bv1.1
• ?M 0.4
• ?81
• w -1.25.

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Dependence on systematics
Systematic errors predominantly affect the
constraints in the w direction, which is
primarily driven by DEEP2 group abundances. SDSS
groups can still provide strong constraints in
the ?m direction (assuming s8 is known), as there
errors are small enough that the shape of the
velocity function is providing significant
constraints.
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What if we had 20x as much area?
Future baryonic-oscillation surveys could be used
to make this same measurement if they are densely
sampled. A 60 square degree survey could yield
tight constraints on w - IF systematics are
well-constrained.
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By combining area with depth, AEGIS allows us to
study rare objects in detail
B. Gerke, JN et al. 2006, AEGIS ApJL, Accepted
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Like a spectroscopically identified, dual AGN at
z0.7
Hb
OIII 4959
OIII 5007
position
l/ z
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HST reveals a fairly-normal early-type host
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AEGIS gives its SED over 9 decades in n