Loading in 5 sec....

Measuring dark energy from galaxy surveysPowerPoint Presentation

Measuring dark energy from galaxy surveys

- By
**ricky** - Follow User

- 76 Views
- Uploaded on

Download Presentation
## PowerPoint Slideshow about ' Measuring dark energy from galaxy surveys' - ricky

**An Image/Link below is provided (as is) to download presentation**

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Connecting dark matter to linear theory

Linear perturbation theory

Evolved matter distribution: MXXL

Angulo et al. 2012

Bias and nonlinear effects

Angulo et al. 2008

Scale dependent RSD

Jennings et al. 2011

The need for improved RSD models

Using linear theory leads to systematic errors similar to difference in signal

Jennings et al. 2011

Measuring DE using galaxy pairs

Marinoni & Buzzi 2010

Peculiar motions distort apparent

distribution of pair angles:

Jennings et al. 2012

A probe of dark energy

- Peculiar velocities give distortion in pair angle distribution
- Probe of Hubble expansion
- Distortion sensitive to nature of dark energy
- Distinguish models with same BAO and halo mass function
- Requires simulations
Jennings et al. 2012

Why build a mock catalogue?

A synthetic galaxy can catalogue be used to:

- Test estimators: e.g. Galaxy clustering, photo-z, group-finders
- Devise new statistics: e.g. pair distortions
- Uncover systematic effects (we already know the right answer)
- Estimate errors
- Generate predictions for different dark energy cosmologies

What is a mock catalogue?

STEP 2

STEP 1

Combine with galaxy

formation model

N-body simulation

A priori calculation

of baryon physics

Millennium, Horizon, MICE, MXXL

e.g. GALFORM; GALICS, LGALAXIES; MORGANA

Springel et al. 2005, Teyssier et al. 2009;

Fosalba et al 2008; Angulo et al. 2012

Cole et al. ;Hatton etal; de Lucia et al; Monaco +

Constructing observer’s past lightcone

STEP 3

Build galaxy catalogue on observer’s past

lightcone.

redshift

e.g. Blaizot et al 2005; Fosalba et al.

Kitzbichler & White; Merson et al.

Apply survey “window function”

- Apply angular footprint
- Apply scanning mask
- Incorporate sampling
- Redshift completeness (synergy with OU-SIM)
- Steps 1, 2, 3 generic
- Step 4 is survey specific

Merson et al. 2012

Merson et al. 2012

Merson et al. 2012

Summary

- Hybrid tool: N-body and galaxy formation sims
- Linear theory not accurate enough for Euclid on large-scales
- Scale dependent: nonlinearities, bias, RSD
- Mock catalogues will help refine estimators
- Devise new tests

Download Presentation

Connecting to Server..