# Presentation: 923528

**Dark Energy**
**with**** SNAP**
**and other**** Next Generation Probes**

**Eric Linder **
**Berkeley Lab**

## Dark Energy to z > 1

***New***** ****parametrization**** **
***w(a)=w******0******+w******a ******(1-a)***

** ****Model independent, 2D phase space **
** ****Well behaved at high *****z***
** ****More accurate reconstruction **
** ****More sensitive to data!**

- Linder 2002
- PRL; astro-ph/0208512

**Time variation w**** ́ is a critical clue to fundamental physics.**

** ****Deep surveys of galaxies and SN to *****z>1***
** ****Large scale structure formation**
** ****CMB constraints from *****z******lss******=1100***** **

## Evolving Equation of State

- Linder 2002, astro-ph/0210217
- following
- Corasaniti & Copeland 2002

***w(a) = w******0******+w******a******(1-a)***
**Accurate to 3% in EOS back to *****z=1.7***** (vs. 27% for *****w******1*****). **
**Accurate to 0.2% in distance back to *****z******lss******=1100*****!**

## SN + CMB Complementarity

**SNAP tightly constrains dark energy models. **
**SNAP+Planck have excellent  complementarity, equal to a prior ********(********M****)********0.01.  **
- Frieman, Huterer, Linder, & Turner 2002
**SNAP+Planck  can detect       time variation w**** ́ at 99% cl           ****(e.g. SUGRA)****. **

## Large Scale Structure 

**Pilot Study with KAOS**

**KAOS: Kilo-Aperture Optical Spectrometer**
**Next generation 2dF survey **
**Gemini South front end (8 meter)**
**4000 fibers, 1.5 sq.deg. FOV **
**400 sq.deg. area, 10****6**** galaxies**

**Linder, Colless**

**Next generation galaxy survey:**** **
**2dF ******** 400dF !**

## Cosmic Shear Test 

**Alcock & Paczy****ń****ski 1979**

- Transverse and radial distances 					  are not equal, *even for a sphere*, 				     because they are measured 					     at different a(t).
- z /  = H(z) dz ́/H(z ́)

**SNAP still offers the best hope to detect w**** ́.**

**Linder astro-ph/0212301**

## KAOS+SNAP: Baryon Oscillations 

**Standard ruler: **
**  ****ratio of wiggle scale to sound horizon ****	****	****	******** ****H(z) / (********m****h****2****)****1/2**
**Just like CMB – simple, linear physics**

- Eisenstein astro-ph/0301623

- Linder astro-ph/0304001

## Growth of Structure 

**Growth in linear perturbation theory with *****w****** ́***

** ****vs. cosmological constant**
** ****vs. constant *****w***
** ****vs. constant *****w***** degenerate in CMB**

**Linder 2002**

## Large Scale Structure 

***running!***

**Growth predicted to be very sensitive to***** ******w****** ́***
**Running blind: SZ, cluster/halo counts, lensing**
**Need full scale LSS simulations with *****w, w****** ́***
**None exist!**** **

**but in planning with C. Frenk, A. Jenkins**
** ****vs. cosmological constant**
** ****vs. constant *****w***
** ****vs. constant *****w***** degenerate in CMB**

## First Simulation Results

** ****10****7**** particles**
** ****L****box****=648 Mpc/h**
** ********M****=0.3 + SUGRA DE**
** ****Linear P****k**** as Hubble LCDM**
** ****Fits Jenkins mass function**
** ****Agrees with Hubble FOF(b0.2) to 5%**

**Jenkins & Linder 2003**

## Expansion History of the Universe

**SNAP will map the expansion  history, uncovering physics just like the thermal history revealed early universe physics. **

## Present Day Inflation

**SNAP will map the expansion history precisely and see the transition from acceleration to**** ****deceleration.**** **

## Beyond Dark Energy

**SNAP can not only determine dark energy parameters, but test the cosmology framework – alternative gravitation, higher dimensions, etc. **

## History constrains Fate

**SNAP will bound the possible fate of the universe. **
**Axion, supergravity, decaying dark energy models leading to collapse of universe have detectable w**** ́****. **

**Collapsing universe (e.g. axion DE)**

**Work in progress, ****	****              with Kallosh, Kratochvil, Linde**

## SNAP Complements SNAP

**SNAP Complements SNAP**

**SN Ia**

**Weak Lensing**

**SN II**

**Clusters**

**Baryon Oscillations**

**Strong Lensing**

**Wide, Deep and Colorful**
** ****9000 times the area of Hubble Deep Field**
** ****15 sq.deg. to AB mag R=30 ; 120 epochs**
** ****300 sq.deg. to AB mag R=28**

## Next Generation Resource

**For Astronomers***** ***
** ****SNAP main survey will be 5000x larger (and as deep) **
**   ****than the biggest HST deep survey, the ACS survey **
** ****Complementary to NGST: target selection for rare objects**
** ****Can survey 300 sq. deg. in a year to J=28 (AB mag)**
** ****Archive data distributed **
** *****Guest Survey Program***** **

**For Cosmologists**
** ****Mapping the expansion history of the universe through the  **
**   ****accelerating phase back into the decelerating epoch **
** ****Precision determination of cosmological parameters**

**For Fundamental Physicists**
** ****Exploring the nature of dark energy **
** ****Testing higher dimension theories **
** ****Testing alternate theories of gravitation**