The Growth of LSS
in a Dark Energy Dominated Universe
A Century of Cosmology
Marc Davis
UC Berkeley
Venice, August 2007
DEEP2 pre-selects high-z
galaxies using observed
colors
Venice, August 2007
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.
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.
Venice, August 2007
A Redshift Survey at z=1:
• 3 sq. degrees
• 4 fields (0.5o x <2o)
• 80 Keck nights, one-hour exposures to RAB=24.1
• primarily z~0.75-1.4 (pre-selected using BRI photometry)
• 46,585 unique redshifts, error ~30 km/s
• ~5·106 h-3 Mpc3
• 1200 l/mm: ~6500-9200 Å
• 1.0” slit: FWHM 68 km/s
• z=0.7-1.4 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
Venice, August 2007
Redshift Distribution of DEEP2
Survey
Venice, August 2007
DEEP2 Status Update
• DEEP2 began observations in July 2002.
• Observations are now >95% finished, with >49k 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, ….
Venice, August 2007
Cluster abundance depends on
cosmology
CDM
CDM
=1
=0.3, =0.7
o 1015 Mo
* 10 14.5-15Mo
. 1014-14.5 Mo
Hubble volume simulations
Brian F. Gerke
Evrard et al. 02
13
2PIGG:Ek
e et al
2004
Redshift Maps in 4 Fields: z=0.7-1.3
Cone diagram of 1/12 of the full DEEP2 sample
Venice, August 2007
Galaxy groups in DEEP2
•Overdensities identified in redshift space.
•Use the VDM algorithm of Marinoni et al. (2002).
position
l, z
•Group in early DEEP2 data s~250 km/sec
Venice, August 2007
DEEP2 Group Catalog
Groups with >350 km/s
Shown are groups for 3 fields
--length of ellipse proportional to velocity dispersion
Venice, August 2007
Gerke et al. 2005, astro-ph/0410721
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
Venice, August 2007
Why search for groups in DEEP2?
•Apparent abundance of groups: dN(,z)/dzd
Provides a useful test of dark energy eq. of state (Newman et al, 2002)
•differences in the volume
element varies by 3x between
w=0 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.
Size of the Universe versus w
Abundance versus Redshift
Gerke etal 2008
Simulated Data!!
Measured dispersion
with galaxies
compared to reality
-- tremendous scatter!
Dispersion with galaxies
Venice, August 2007
We can reconstruct the quantity we
need with the VDM
Successful above ~350 km/s
• We want to measure
N(σ, z) to constrain
cosmology.
• Tests on the mock
catalogs indicate that we
can measure N(σ,z) in
DEEP2 accurately for
σ>350 km/s.
Venice, August 2007
Brian F. Gerke
Projected constraints
Computed with DM
halos in simulated
DEEP2 and 2dF
light cones,
constructed from
the Millennium Run.
input cosmology
Venice, August 2007
Brian F. Gerke
In each panel, the
suppressed
parameter is held
fixed.
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”
Measuring Kaiser infall in (rp,)
et al, 2008
•The blue galaxies show fully developed coherentCoil
infall
pattern on scales >5 Mpc, as expected.
•The red galaxies have very extended fingers of god, as
expected.
Kaiser infall, MOCKS
Coil et al, 2008
Millenium mocks, not a bad approximation
Conclusions on DEEP2
• DEEP2 observations are >99% 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!
Venice, August 2007
By combining area with depth, AEGIS
allows us to study rare objects in detail…
B. Gerke, JN et al. 2006, AEGIS ApJL, Accepted
Venice, August 2007
Like a spectroscopically
identified, dual AGN at z=0.7
Hb
[OIII]
5007
position
[OIII]
4959
Venice, August 2007
l/ z
HST reveals a fairly-normal early-type
host
Venice, August 2007