Guilhem Lavaux

Workshop "Deciphering the Dynamic Universe"

Statistical reconstruction and simulation of the initial conditions of our Local Universe

(PLUS project)

November 27th 2014

Institut d'Astrophysique de Paris / CNRS

Collaboration: J. Jasche, S. Peirani, PLUS collaboration

Motivation

● Galaxy catalogues static picture of the Universe

● Large scale structurenon-trivial statistical properties

● Initial conditions trivial (and a test is interesting per se)

● Foreground/selection effects must be taken care of

complementary observationsConstrained simulations

A static picture of Local Universe

2M++, Lavaux & Hudson (2011)

Completeness at K=11.5 Completeness at K=12.5

Galaxy distribution

The 2M++ galaxy redshift catalogLavaux & Hudson (2011, MNRAS)

Local Universe simulation (PLUS)

Aim: Biggest and most accurate simulation of the Local Universe

Current observational base: 2M++ (Lavaux & Hudson 2012)

BORG(Jasche & Wandelt 2013)

2M++ dataset SFI++/Taipan/6dFLarger surveys (2MPZ...)

SuperVelMod(Lavaux 2014)

Small scale improvements (10-15 Mpc/h subbox, enforce distances)

Local Group + Local Sheet simulation

Large scale Initial conditions(600 Mpc/h, 2563 phases, extended to 10243)

Dark MatterBaryon physics

Fine bias calibration

DONE TO DO NEW TECHNOLOGY

The BORG data model

−logP (δ ,α ,~n )=A+∑i

~n R i(1+δNL ,i [δ ])α−N iα log (1+δNL, i [δ ])+∑k

| δ̂k |2

2 Pk

Field derived from Cloud-In-Cell + 2LPT dynamicsδNL [δ]

Linear response operator (mask, radial selection)

« Mean » density of tracers

NGP binned data

Poisson probabilityGaussian prior

bias

sampled using Hamiltonian Monte Carlo algorithmδ

Parameter exploration using HMC

Evolve system with Hamiltonian dynamics

Pump and dump energy in the system by varying

Create an Hamiltonian :

Assimilate the posterior to a potential energy :

Compute acceptance :

Generate a MC sample dropping the state of

Parameter exploration using HMC

Evolve system with Hamiltonian dynamics

Pump and dump energy in the system by varying

Create an Hamiltonian :

Assimilate the posterior to a potential energy :

Compute acceptance :

Generate a MC sample dropping the state of

INVOLVE GRADIENT COMPUTATIONS !INVOLVE GRADIENT COMPUTATIONS !

Power spectrum / Phase convergence

0.1 1

10-6

10-5

10-4

10-3

10-2

10-1

Large scale structure detection and caracterization

Binned distribution of galaxies

Sloan Wall

Final dark matter density distribution

Sloan Wall

Dark matter density distribution (ARES view)

Sloan Wall Mpc/h

Mpc/h

Supergalactic plane

Shapley concentration

Coma

Pisces-Cetus

Perseus-Pisces

?

Another example: Tully's void

Thick 2M++ slice (± 20 Mpc/h), Density field in the galactic plane

Another example: Tully's void

Thin HIPASS slice (± 20 Mpc/h), Density field in the galactic plane

BORG/DIVA structure classification

Dynamically based structure classifier (DIVA, Lavaux & Wandelt 2010)

Only possible when displacement field is available

BORG !

MC Sample Displacement +Shear field

DIVA classification (Watershed + Eigenvalues)

Initial condition voxel marking

Lagrangian transport

Eulerian classification MC Map

Lavaux & Jasche (in prep.), Leclercq et al. (arxiv : 1410.0355)

Another example: Tully's void

Thin HIPASS slice (± 20 Mpc/h), Density field in the galactic plane

Void probability density in the galactic plane (DIVA criterion), HIPASS slice (± 10 Mpc/h)

Structure finding with BORG/DIVA

Full resimulation

Initial conditions

Sloan Wall

Local Universe Simulation

600 Mpc/h, 60 Mpc/h projection, 5123 dark matter PLUS collaboration

OTHER MOVIE

2M++ galaxy catalogue (Lavaux & Hudson 2012)

Local Universe Simulation

Large scales: BORG (Jasche & Wandelt)

600 Mpc/h, 200 Mpc/h projection, 10243 dark matter PLUS collaboration

2M++ galaxy catalogue (Lavaux & Hudson 2012)

Local Universe Simulation

Large scales: BORG (Jasche & Wandelt)

600 Mpc/h, 60 Mpc/h projection, 20483 dark matter, z=1 PLUS collaboration

Conclusion

Full resimulationStructure prediction

and/or classification

BORG

Galaxy surveys + Data model (selection, bias, completeness, ...)

Final density Initial density

Preliminary results 5123, 10243 (20483 to come)

Stable large scale structuration

PLUS project - redshift space distortion - Local Group dynamics - hydrodynamics

Available ensemble final density fields

Showcases for Tully's void and Sloan Wall