Transcript Lick Survey 1 million galaxies!

ONE MILLION
GALAXIES
Cosmography and Cosmology
Michael S. Vogeley
Department of Physics
Drexel University
XXXVth Recontres de Moriond, Energy Densities in the Universe
Quantitative Large-Scale Structure: Lick Survey
1 million galaxies!
Lick observatory plates
Counts by eye (ShaneWirtanen), map by
Seldner et al. 1977
Analyses by Peebles,
Groth, and Fry, et al.
Angular correlation
functions: 2, 3, 4-pt
Groth & Peebles (1977)
Michael S. Vogeley, Drexel University
Hints of Greatness: The Shift to 3D
The Photon-Counting Cowboys
Kirshner et al. (1981)
KOSS (1981):
50 Mpc/h Void in Bootes
Anomalous?
Truly empty?
Formation mechanism?
Center for Astrophysics (1982):
Power-law 3D correlations
Pairwise velocity dispersion
Predict gravity field
Comparison with N-body sim’s
“Frothy…filamentary superclusters”
Davis & Peebles (1983)
Michael S. Vogeley, Drexel University
Voids, Walls, and Peaks: Death to CDM?
CfA slice(1986), CfA2, SSRS:
Structures as large as survey
Voids fill space
P(k) rules out SCDM
Geller & Huchra (1988)
APM galaxy catalog (1990):
Too much large-scale power
for SCDM
BEKS pencil-beams (1990):
128 Mpc/h Peaks in 1D P(k)
Characteristic scales in LSS?
Maddox et al. (1990)
Michael S. Vogeley, Drexel University
All-Sky: The IRAS z Surveys
IRAS 2Jy (1989), 1.2Jy (1993)
QDOT (1991), PSCz 0.6Jy (1999)
Selection of galaxies independent
of photo plates, Galactic extinction
IR-selected trace same structures
with lower density in clusters
Similar statistics, but
lower clustering amplitude
Clear evidence for biasing on
all scales
All-sky benefits:
spherical window
density-velocity study
Michael S. Vogeley, Drexel University
Saunders et al. (2000)
CCD-Based Surveys and the Era of Multiplexing
Shectman et al.
(1996)
Las Campanas Redshift Survey:
R-band CCD driftscan photometry
100 Fiber-fed spectrograph
Ubiquitous voids and walls
- the end of “greatness”?
Peak in the 2D power spectrum near
same scale as BEKS
Limited by geometry
What if we survey the whole sky?
Landy et al. (1996)
Michael S. Vogeley, Drexel University
Current Status on Large-Scale Structure
• What drives structure formation?
– Gravity!
• Cosmological parameters?
matter  0.2  0.4,   1  matter, h  0.7
• Components of mass-energy density?
– Baryon fraction (?), CDM, HDM?, what else?
– Is the cosmological “constant” constant?
• Galaxy formation: connecting mass to light
– Gastrophysics and biasing
Michael S. Vogeley, Drexel University
Critical Issues for Large-Scale Structure
• Features in P(k) at peak scale
and beyond
– Is the peak too sharp?
– Wiggles in the spectrum?
– Structure on Gpc scales?
Vogeley (1999)
• Messy details about galaxies
– Galaxy segregation (“biasing”)
– Galaxy evolution (purely
local?)
– Voids: Are they too empty?
Michael S. Vogeley, Drexel University
Blanton et al. (1999)
Features in the 3D Power Spectrum
Baryonic Wiggles
Eisenstein & Hu (1998)
LSS+CMB
Gawiser & Silk (1998)
Slope agreement at small scale
Linear to non-linear transition
Feature at 0.1-0.2h/Mpc
Peak at 0.03-0.04h/Mpc
Slope, ampl <0.03?
Physics on peak scale?
LSS vs. CMB
Michael S. Vogeley, Drexel University
Voids and Void Galaxies
De Lapparent, Geller, & Huchra (1986)
Cen & Ostriker (1998)
Data vs. N-body+hydro:
sim voids too empty?
Data vs. N-body+SAMs:
sim void edges not sharp?
Diaferio et al. (1999)
Galaxy evolution at   0.8
Need color, spectra, low SB, mag range
Michael S. Vogeley, Drexel University
Desiderata for New Galaxy Surveys
Observational Systematics
Measured Galaxy Properties
Photometry
• Large area
• Consistent, accurate
calibration
• Galactic extinction
Spectroscopy
• Large depth
• Complete sampling
• Careful target selection
• Multi-wavelength
• Surface-brightness
• Resolve features
• Wavelength range
Michael S. Vogeley, Drexel University
A Survey of Surveys
Colless (1999)
Vogeley (1999)
Michael S. Vogeley, Drexel University
Volume and Number Surveyed
1.00E+09
SDSS
photo-z
1.00E+08
No of objects
1.00E+07
SDSS
main
SDSS
abs line
1.00E+06
SDSS
red
1.00E+05
CfA+
SSRS
2dF
LCRS
1.00E+04
SAPM
1.00E+03
1.00E+04
2dFR
1.00E+05
1.00E+06
QDOT
1.00E+07
1.00E+08
1.00E+09
Volume in M pc 3
Michael S. Vogeley, Drexel University
1.00E+10
1.00E+11
www.sdss.org
Michael S. Vogeley, Drexel University
Features of the SDSS
Unique 2.5m telescope, located at Apache Point, NM
3 degree diameter field of view
Two surveys in one:
Photometric survey in 5 bands
Spectroscopic redshift survey
CCD Mosaic Camera
30 CCDs 2K x 2K (imaging)
22 CCDs 2K x 400 (astrometry)
Two double spectrographs
2 x 320 fibers (3 arcsec diameter)
resolution  / =2000
Spectral coverage from 3900Å to 9200Å
Automated data reduction
Over 70 man-years of development effort
(Fermilab + collaboration scientists)
Very high data volume
40 TB of raw data
About 1 TB of catalog data
Data made available to the public
Michael S. Vogeley, Drexel University
SDSS: The Photometric Survey
Northern Galactic Cap
drift-scan imaging of 10,000 square degrees
5 broad-band filters
pixel size is 0.4 arcsec
> 800 billion pixels x 5 filters
20 TB raw imaging data  pipeline
100,000,000 galaxies
50,000,000 stars
Southern Galactic Cap
multiple scans (> 30 times) of one stripe
another 20 TB of raw imaging data
detect fainter, variable, and
moving objects
Continuous data rate of 8 Mbytes/sec
Michael S. Vogeley, Drexel University
The First Stripes: 600 sq.deg. done, 9400 to go!
Camera:
5 color imaging of 600 square degrees
Multiple scans across the same fields
Photometric limits as expected
PSF variations taken out in software
Michael S. Vogeley, Drexel University
SDSS: The Spectroscopic Survey
Spectroscopic targets:
1 million galaxies (main + BRG)
100,000 quasars
100,000 stars
selected objects from other catalogs
Two high-throughput spectrographs
spectral range 3900-9200 Å
640 spectra simultaneously
resolution  / =2000
Automated reduction of spectra
redshift
spectral features
classification
The result: A redshift map to z=0.2 and beyond
Michael S. Vogeley, Drexel University
Status Report on SDSS Spectroscopy
12 plug-plate fields
r’=18
galaxy
z=0.19
Both spectrographs fully operational
>7,000 test spectra at survey spec.
Measured throughput: 15%, 20%
Redshift completeness: 98%
Michael S. Vogeley, Drexel University
Discovery of the Highest-Redshift Quasars
Eight of the ten highest redshift
quasars have been found in the
first SDSS test data
Michael S. Vogeley, Drexel University
Finding Rare Objects
Distant QSO’s are outliers
in color-color space
The SDSS analysis pipeline automatically
discovers candidate objects for
spectroscopic followup
Michael S. Vogeley, Drexel University
SDSS Commissioning-Data Science
High-z quasars
Methane, L dwarfs
Structure of Galactic halo with RR Lyrae
Galaxy-galaxy weak lensing
Galaxy-galaxy lensing detected in 1/44 of SDSS
Magnification bias from lensing
Clusters of galaxies, X-ray sources
Compact groups of galaxies and correlations
Angular correlations of galaxies
IR, FIRST sources
Quasar-galaxy cross-correlations
Carbon stars
QSO absorption line systems
Michael S. Vogeley, Drexel University
Fischer et al. (1999)
SDSS 2.5m Observation Schedule
May 1998 - March 1999
First light imaging - equatorial only
Camera and software commissioning
April 1999
Telescope pointing model
Great circle scan tests
Spectrograph flexure tests
May 1999
Spectrograph testing
Great circle driftscan imaging
June 1999
First astronomical spectroscopy
Fall 1999
Spectroscopic commissioning
Target selection tests
March 2000
Survey proper begins
Michael S. Vogeley, Drexel University
Outlook: A Golden Age for Structure Formation*
Independent probes of structure out to 1Gpc
High-resolution power spectra
Sampling the same wavelength scales at z=0, 1000
Multi-variate distribution of galaxies
Photometric, spectroscopic properties
Evolution of populations
Segregation and “biasing”
Multi-wavelength data bases
Integration of X-ray, UV, Optical, IR, Radio surveys
On-line digital data access
Data mining methods
* “You fool, there were no good old days. You’ve simply romanticized
the agony of freezing all night in the prime-focus cage.” - F. Zwicky (perhaps)
Michael S. Vogeley, Drexel University