Photometric redshifts for deep large surveys

1
Photometric redshifts for deep large surveys

• PAU- A new point of view

Pol Martí Sanahuja IFAE Thursday Meeting April,
23th of 2009
2
New cosmology, new observables

• The shape of the universe
• Space-time metric

Space-time Metric
Space-time line element
Distance between two separated points
Space-time metric depends on
- Coordinate system
Minkowski metric
- Space-time curvature
3
New cosmology, new observables

• The shape of the universe
• Cosmological principle
• We does not occupy a privileged location in the
  universe.
• Universe has the same appearance independently
  of where you are looking from.

Homogeneity and Isotropy of the universe
4
New cosmology, new observables

• The shape of the universe
• Friedman-Robertson-Walker (FRW) metric

Cosmological principle

5
New cosmology, new observables

• The shape of the universe
• Friedman-Robertson-Walker (FRW) metric

FRW
Minkowski
Diferences
Scale factor
Curvature factor
k 1 -1 0
6
New cosmology, new observables

• Cosmological redshift
• Photons trip across the FRW metric

Eq. of motion
Geodesic equation
Christoffel symbols
Geodesic equation

FRW metric

De Broglie hypothesis
7
New cosmology, new observables

• Cosmological redshift
• Definition

8
New cosmology, new observables

• Cosmological redshift
• Consequences on the spectra

9
New cosmology, new observables

• The evolution of the universe
• Einstein equations

Energy-moment. tensor
Einstein tensor
10
New cosmology, new observables

• The evolution of the universe
• Perfect fluid

Energy density
Caracterized by its rest frame
Pressure

• Properties
• No shear stresses
• No viscosity
• No heat conduction

Energy-momentum tensor
State equation
Dust
Radiation
Curvature
11
New cosmology, new observables

• The evolution of the universe
• Friedman-Lematier equation

Einstein equations (with perfect fluid)

FRW Metric
Solution
Hubble parameter
Density parameter
Critical density
12
New cosmology, new observables

• Observables
• Angular distance

13
New cosmology, new observables

• Observables
• Hubble diagram

High-z terms only depend on the universe
multicomponent content
14
New cosmology, new observables

• Observables
• Hubble diagram
• 1998 Perlmutter et al.
• said Universe
• expansion is
• accelerating

Dark Energy
Negative Pressure!
15
New cosmology, new observables
What Dark Energy is made of ?
More precise measures are required to determine ?
accurately and answer this question
Deep surveys
16
Measures

• BAO scale as standard ruler
• When t lt trec 240.000 yr

Universe components were
Relativistic
Highly coupled gas

Cold Dark Matter
Initial over-density of components
Sound wave
Overpressure in highly coupled gas
17
Measures

• BAO scale as standard ruler

D. Eisenstein, http//cmb.as.arizona.edu/eisenste
/acousticpeak/
18
Measures

• BAO scale as standard ruler
• When t trec 240.000 yr

Hydrogen atoms are formed
Strong interaction in the gas disappears
Overpressure vanishes
Wave stalls at a radius of 150Mpc
19
Measures

• BAO scale as standard ruler

D. Eisenstein, http//cmb.as.arizona.edu/eisenste
/acousticpeak/
20
Measures

• BAO scale as standard ruler
• When t gt trec 240.000 yr

150Mpc away over-density in gas attracts Dark
Matter
Galaxies are preferably separated 150Mpc

Dark Matter halos seeds the formation of galaxies
Standard Ruler
21
Measures

• BAO scale as standard ruler

Standard Ruler
D. Eisenstein, http//cmb.as.arizona.edu/eisenste
/acousticpeak/
22
Measures

• BAO scale as standard ruler

23
Measures

• BAO scale as standard ruler

24
Measures

• BAO scale as standard ruler

D. Eisenstein, http//cmb.as.arizona.edu/eisenste
/acousticpeak/
25
Measures

• BAO scale as standard ruler
• Galaxy-Galaxy correlation function

D. Eisenstein, http//cmb.as.arizona.edu/eisenste
/acousticpeak/
BAO shape
D. Eisenstein, http//cmb.as.arizona.edu/eisenste
/acousticpeak/
26
Measures

• BAO scale as standard ruler
• Galaxy-Galaxy correlation function

We need enough amount of galaxies to determine
accurately galaxy-galaxy correlation function
Large surveys
27
Measures

• LRG as a mass tracer

Luminous Red
Galaxies
Most-luminous galaxies in Universe
Universe is full of them
Old stellar systems
Uniform caracterized spectrum
Accurated photometric redshift measures!
Prove large cosmological volumes!
Prove deep cosmological distances!
28
Measures

• Photometric redshift
• What do we need?
• What do we obtain?

29
Measures

• Photometric redshift
• How do we measure it?

30
Measures

• Photometric redshift
• How do we measure it?

31
Measures

• Photometric redshift
• How do we measure it?

32
Measures

• Photometric redshift
• How do we measure it?

33
Measures

• Comparison between Photo. and Spectr. redshift
• Uncertains
• Exposure times

sPhoto gtgt sSpectro
tSpectro gtgt tPhoto
Big amount of exposures
Photometric redshift are more optimum for
large surveys!
Large surveys
Big statistics
34
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• Features
• 14106 LRGs
• 8000 deg2
• 0.1ltzlt0.9
• 9 h-3 Gpc3
• 42 filters
• szlt0.003(1z)

High redshift precision
(szlt0.03(1z) SDSS filters)
35
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• How do we get this high precision?

36
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• How do we get this high precision?

37
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• How do we get this high precision?

Low resolution spectrum
38
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• Why do we need this high precision?

PAU survey will detect BAO using
Angular power spectrum Cl
A new point of view!

Radial power spectrum PK
39
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• Why do we need this high precision?

sZlt0.003(1z) is required to measure BAO scale in
the line-of-sigth
Benitez et al. 2009
40
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• Expected results

Benitez et al. 2009
Benitez et al. 2009
41
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• Expected results

Benitez et al. 2009
42
Deep and Large Survey

• PAU (Physics of the Accelerating Universe)
• Comparison with other proposed BAO surveys

Benitez et al. 2009
43
Conclusions

• General Relativity discovery and Cosmological
  Principle formulation
• give us New Cosmology theory and New Observables
• New observables like Redshift require Deep
  Surveys to parametrize our univers and to study
  Dark Energy nature
• BAO Scale is a good Standar Ruler but its
  detection requires Large Surveys

44
Conclusions

• Luminous Red Galaxies are good mass tracers to
  detect BAO
• Photometric Redshift is the most optimum method
  to measure LRG redshifts
• The PAU survey is relevant because it uses 42
  filters that provide less than 0.003 redshift
  errors so, it can detect BAO in the
  line-of-sigth.