# Presentation: 470569

## The Sloan Digital Sky Survey 

- Huan Lin
- Experimental Astrophysics Group
- Fermilab

## Sloan Digital Sky Survey (E885)

- Goal:
- Conduct fundamental research in
-    cosmology, particularly formation
-    & evolution of galaxies and large
-    scale structure
- Approach:
- Digital map of 1⁄4 of sky in 5 bands
- Spectra of 1 million galaxies,
-                  100,000 quasars
- Resources:
- 	2.5 m telescope in New Mexico
- 	Large CCD camera
- 	640 fiber spectrograph
- 	13 partner institutions

## Partner Institutions

- Fermi National Accelerator Laboratory
- Princeton University
- University of Chicago
- Institute for Advanced Study
- Japanese Promotion Group
- US Naval Observatory
- University of Washington
- Johns Hopkins University
- Max Planck Institute for Astronomy, Heidelberg
- Max Planck Institute, Garching
- New Mexico State University
- Los Alamos National Laboratory
- University of Pittsburgh

## Funding Agencies

- Alfred P. Sloan Foundation
- Participating Institutions
- NASA
- NSF
- DOE
- Japanese Monbukagakusho
- Max Planck Society

## FNAL in SDSS

- Role:
- 	Data acquisition
- 	Data processing
- 	Survey Planning
- 	Data distribution
- 	Support telescope and instrument systems
- Science:
- 	Galaxy correlation functions
- 	Weak lensing
- 	Galaxy clusters
- 	Milky Way halo structure
- 	Galaxy evolution
- 	QSO luminosity functions
- 	Near Earth Asteroids
**Of 103 refereed papers, 17 have current or former FNAL scientist or student supervised by FNAL as lead author**

- Participants
- 	**EAG**
- 	TAG
- 	PPD
- 	Comp. Comm. Fab. (CD)

## HOW THE SDSS SURVEY WORKS

## Apache Point Observatory, 

- New Mexico

## 2.5-m Telescope

## The Mosaic Camera

**2.5 degree wide field of view**
**30 photometric CCDs (each 2048 x 2048 pixels)**
**6 columns of 5 filters (ugriz) **

## Survey Layout

- North Galactic Hemisphere

- South Galactic Hemisphere

**Mosaic camera scans along great circles on the sky**

## Color coding:  g  r  i    (3 images taken in succession over 8 minutes)

- Color coding:  *g  **r  **i    *(3 images taken in succession over 8 minutes)

- Two interleaved scans (run 259, 273) taken on successive nights, Nov 1998

## Apache Point

- Obs.

- Fermilab

- Data Tapes

- Plug plate designs

- Plug plates

- U. of Washington

## 3. Identify Galaxies,

-     Quasars

## 4. Design

-     Plates

- 3 deg diameter
- 7 sq deg area

## Tiling

- Survey tile centers and target assignments to tiles are optimized

- Blanton et al. 2003,
- AJ, 125, 2276

- Sampling Rates:
- >92% all targets
- >99% non-colliding

## Plugging the fibers

- 592 science targets
-   16 calibration stars
-   32 skies
- 640 fibers

## 5. Spectroscopy

- Spectra of 100 objects out of 640 Total

- Wavelength

## Elliptical galaxy spectrum  z=0.12

## Spiral galaxy spectrum  z=0.089

## Quasar spectrum  z=4.16

## Imaging

- Sky Coverage

- 74% as of May 30, 2003
- 6255/8452 square degrees

- Spectroscopy
- Sky Coverage

- 47% as of May 27, 2003
- 794/1688 tiles

## Status of data collection (May 2003)

- Imaging
- 6255 sq deg “unique” imaging in hand
- 22 terabytes processed through pipelines (including reprocessing)
- Spectroscopy
- 794 “unique” tiles
- 139 additional special purpose plates
- ~50,000 Quasars
- ~300,000 Galaxies
- (bigger than 2dF survey)

## Access & Distribution of SDSS Data

- I. Early Data Release (EDR)
- June 2001
- Commissioning data + first survey quality data
- 460 sq deg. + 24,000 spectra
- II. Data Release 1 (DR1β)
- April 2003
- 2099 sq. deg. + 150,000 spectra
- 3 Terabytes total

## Slide 24

## Data Access Mechanisms

- http://www.sdss.org/dr1/
- Data Archive Server
- Footprint
- Finding Chart
- Image Query Server
- Spectro Query Server
- rsync or http access to flatfiles
- Volume: 1 square degree = 1 Gbyte.

## Show Blanton sample11 animation

## Large Scale Structure:
Galaxy Power Spectrum

- Galaxy Power Spectrum

## Cosmic microwave background (CMB) fluctuations measured by WMAP 

- Cosmic microwave background (CMB) fluctuations measured by WMAP

## Evolution of large scale structure with redshift in a variety of N-body simulations

- The clustering of galaxies observed today evolved from the initial quantum fluctuations in the early universe.

## Sample:  205,443 galaxies    2417 sq deg    mean redshift z = 0.1

- Tegmark et al. 2003

- Sample:  205,443 galaxies    2417 sq deg    mean redshift z = 0.1

- Shown: 66976 galaxies within 5° of equatorial plane, color coded by absolute magnitude

## Calculate 3D galaxy power spectrum by expanding galaxy distribution in pseudo-Karhunen-Loève eigenmodes, accounting for complicated survey geometry

- Tegmark et al. 2003

- Calculate 3D galaxy power spectrum by expanding galaxy distribution in pseudo-Karhunen-Loève eigenmodes, accounting for complicated survey geometry

- Example modes in equatorial plane

- Example angular modes on sky

## Wavenumber

- Tegmark et al. 2003

- 3D Galaxy Power Spectrum

- Relative Clustering Bias

- WMAP fit flat, ΩΛ=0.73 (Spergel et al. 2003)

- Real-space power spectrum of L* SDSS galaxies

## Power Spectrum

- Tegmark et al. 2003

- Wavenumber

- SDSS P(k) fit: Ωm = 0.291 ± 0.023   L* galaxy σ8 = 0.93 ± 0.02

- fixed: h = 0.72, baryon fraction Ωb/Ωm = 0.17, spectral index ns=1

## Debris in the Milky Way Halo(Yanny, Newberg, ...)

## O

**O**
**B**
**A**
**F**
**G**
**K**
**M**
**L**
**T**

**u     g     r     i     z**

- 50000 K
- 20000 K
- 10000 K
-   7500 K
-   5500 K
-   3500 K
-   2000 K
-   1200 K
-     900 K

- 20
- 10
-   5
-   2
-   1
-  0.7
-  0.4
-  0.1
-  0.05

- Mass (Solar)

- Temperature

## m-M = 5log d(pc) + 5

- M = +4.2 (g' band)
- magnitude             distance

- 0.1 < g'-r' < 0.3
- (Color selection)

-    17                      3.6
-    18                      5.7
-    19                      9.1
-    20                     14.4
-    21                     22.9
-    22                     36.3
-    23                     57.5 (kpc)

- As the Milky Way
- disk has a radius
- of about 10 kpc,
- F stars of this
- mag are well suited
- to explore structure.

## Sagittarius

- North stream

- South Stream

- New
- Structure?

- Monoceros
- Structure

- F stars along
- Celestial
- Equator

## Rings around the Galaxy

**Rings around the Galaxy**
- (Yanny & Newberg)

## No  precession in Spherical potential

- In flattened potential, can hit points above
-                                                                  and
-                                                                  below
-                                                                  the
-                                                                  plane
-                                                                  on
-                                                                  side
- of the Galaxy.

- q=1.0

- q=0.7

- unreachable in same orbit

## Summary

- SDSS status: 74% complete imaging, 47% spectroscopy (May 2003)
- Public Data Release 1 (beta) now available
- http://www.sdss.org/dr1
- Science
- Today discussed the galaxy power spectrum and galactic structure
- Many, many other topics, e.g. quasars, galaxy clusters, lensing, luminosity functions, rare stars, GRB counterparts, asteroids, ...
- http://www.sdss.org/publications

## The Supernova Acceleration Probe (SNAP) 

- Huan Lin
- Experimental Astrophysics Group
- Fermilab

## Energy budget of Universe

***Dark***
***Energy:***
***65%***

***Dark***
***Matter:***
***30%***

*Energy budget of Universe*

## Current SN Results

- Two groups, the Supernova Cosmology Project and the Hi-Z Team, find evidence for an accelerating Universe.

- (from A. Kim)

## SNAP Science Goals and Project Design

- Discover large numbers of supernovae (2000)
- Look back 3 - 10 billion years (z=0.5 - 1.7, light is redshifted up to 1.7 um)
- Measure each supernova in detail (light curve, spectrum)

- Large 2 meter class telescope, large field of view (0.7 sq degree)
- Dedicated space-based mission
- Visible to near-infrared camera
- Space-based to avoid absorption in earth’s atmosphere
- Detailed spectrum at maximum light to characterize supernovae
- Observing program of repeated images in visible to near-infrared

- (from S. Perlmutter)

## SPACECRAFT CONFIGURATION

- Main Baffle Assembly

- Door Assembly

- Primary Solar Array

- Secondary Mirror Hexapod
- and “Lampshade” Light Baffle

- Secondary Metering Structure

- Primary Mirror

- Optical Bench

- Instrument Metering Structure

- Tertiary Mirror

- Fold-Flat Mirror

- Spacecraft

- Shutter

- Instrument Bay

- Instrument Radiator

- Solar Array, ‘Dark-Side’

## SNAP Telescope

- 2-m primary aperture, 3-mirror anastigmatic design.
- Provides a wide-field flat focal plane.

- (from A. Kim)

## Instrumentation: Imager

**A large solid-angle camera (****0.7 square degrees****) provides multiplexed supernova discovery and followup.**
**Covers wavelength region of interest, ****0.35- 1.7 microns****.**
**Fixed filter mosaic on top of the imager sensors.**
**3 NIR bandpasses****.**
**6 visible bandpasses****.**
**Coalesce all sensors at one focal plane.**
**36 2k x 2k HgCdTe NIR sensors covering 0.9-1.7 ****μ****m****.**
**36 3.5k x 3.5k CCDs covering 0.35-1.0 ****μ****m****.**

- rin=6.0 mrad;  rout=13.0 mrad
- 	rin=129.120 mm;  rout=283.564 mm

**CCDs**
- Guider
**HgCdTe**

- Spectr. port

**Spectrograph**

- (from A. Kim)

## Detailed Imaging and Spectral Data for SNAP Supernovae

*Images*

*Spectra*

*Redshift & SN Properties*

*Lightcurve & Peak Brightness*

- At every moment in the explosion event, each individual supernova is “sending” us a rich stream of information about its internal physical state.

- (from S. Perlmutter)

## Simulated SNAP data

- Each SNAP point
- represents ~50-supernova bin

- (from S. Perlmutter)

- Redshift

- Relative Magnitude Difference

## Dark Energy Equation of State

## SNAP@Fermilab Science Interests

- Supernova Survey: 15 deg2, deep but narrow
- Wide Area Survey
- Unprecedented combination of area, imaging and redshift depth, optical/near-IR coverage, and spatial resolution
- Default 300 deg2, Fermilab investigating optimization, in particular wider 1000 deg2 survey
- Complementary, powerful constraints on dark energy from weak lensing and cluster abundances
- Also many non-dark energy science applications (e.g., galaxy clustering and evolution) because 106 times Hubble Deep Field area

## Galaxy Cluster Abell 1689

- SDSS (ground)

- HST (NASA, Benitez et al.) Comparable depth and resolution as SNAP

## Weak Lensing Angular Power Spectrum 

- Weak Lensing Angular Power Spectrum
- from SNAP Wide Area Survey

- Refregier et al. (2003)

## Cosmological Parameter Constraints from Supernovae vs.Weak Lensing

- Equation of State

- Matter Density

- Refregier et al. (2003)

## Cosmological Parameter Constraints from Supernovae vs. Cluster Counts

- Levine et al. (2002)

- Equation of State

- Matter Density

- 1000 deg2 cluster survey (z < 1.2)

- 400 supernovae from space

## SNAP@Fermilab Status

- Web page http://snap.fnal.gov/
- SNAP Wide Area Survey white paper submitted to PAC
- Working Groups
- Photometric Calibrations
- Electronics
- Radiation Shields
- Simulations and Science
- Software and Data Processing
- SNAP collaboration membership application pending
- Fermilab approval pending