How to Zoom: Lagrange volumes and Other Halo Properties

Transcription

1 How to Zoom: Lagrange volumes and Other Halo Properties Jose Oñorbe Fulbright Postdoctoral University of California Irvine In collaboration with S. Garrison-Kimmel (UCI), J. Bullock (UCI), A. Maller (CUNY), M. Rocha (UCI) & O. Hahn (Stanford). August 18, 2012 Galaxy Simulation Comparison Project Workshop

2 How to do a zoom (zoom-in/multimass/multiresolution/nested) simulation Pipeline 1 Choose parameters: z ini, resolution, cosmology, etc 2 Run dark matter only simulation 3 Identify the desired halo to zoom 4 Calculate the Lagrange volume region to re-simulate 5 Create ICs 6 Run zoom-in simulation. Check for contamination Jose Oñorbe How to Zoom: Lagrange volumes 2

3 How to do a zoom (zoom-in/multimass/multiresolution/nested) simulation Using MUSIC (Hahn & Abel 2011) Pipeline 1 Choose parameters: z ini, resolution, cosmology, etc 2 Run dark matter only simulation 3 Identify the desired halo to zoom 4 Calculate the Lagrange volume region to re-simulate 5 Create ICs 6 Run zoom-in simulation. Check for contamination Lagrange volume definitions? How do Lagrange volumes correlate with other properties? Improve method to guarantee no contamination? How does contamination really affect the halos? Jose Oñorbe How to Zoom: Lagrange volumes 2

4 Lagrange volume Definitions Which particles do you trace back to z ini? N r vir, mainbranch(z), tree(z), fixed size, etc How do you define the volume at z ini? Convex hull, Cuboid, Sphere, etc Jose Oñorbe How to Zoom: Lagrange volumes 3

5 Part I: Full box simulations Simulations resolution: 128 3, 256 3, L box : 5, 10, 25, 50, 150, 650, 900 Mpc/h z ini codes: GADGET and ENZO hydro: adiabatic test runs Properties analysis: AMIGA HALO FINDER (AHF;Knollmann & Knebe 2009) M vir, V max, λ, shape, T, conc., a 50, # mergers,... Environment. D x,y (distance to the nearest halo B with mass over y M vir divided by r B vir ). N x,y (# of neightbours with mass > x M vir in a radius y) Lagrange volumes. Selecting the particles: 1, 2, r vir, r 200, Mainbranch, Tree approach. Defining the volume: cuboid, sphere, convex hull Jose Oñorbe How to Zoom: Lagrange volumes 4

6 Lagrange volumes Same box. Different resolutions Lagrange volume = 500 particles F07: low res (128 3 ) F08: med res (256 3 ) F09: high res (512 3 ) Jose Oñorbe How to Zoom: Lagrange volumes 5

7 Lagrange volumes Same box. Different resolutions Normalize by Vol vir = 4π 3 r 3 vir Lagrangevolume VirialVolume Resolution effects = = 500 particles F07: low res (128 3 ) F08: med res (256 3 ) F09: high res (512 3 ) Jose Oñorbe How to Zoom: Lagrange volumes 5

8 Lagrange volumes: Resolution lower-res/highest-res Lag. vol. /V olc,1 hr V ol c,1 lr Same box. Different resolutions. No subhalos and N hr part > particles L50-x64 L50-x8 L25-x64 L25-x8 mass x8 mass x64 lower-res/highest-res Vmax/V max hr Vmax Agreement L50-x64 L50-x8 L25-x64 L25-x Npart hr Npart hr # of particles in highest-res sim Single halo Lagrange volume increases with increasing resolution The smaller the level of zoom relative to initial box for Lagrange vol. calculation, the better for contamination Jose Oñorbe How to Zoom: Lagrange volumes 6

9 Correlations with other halo parameters log T log Vmax/V vir log c/a log D1, log z50 log λ log N neigh 3 log V olch lag V ol vir log V olc lag V ol vir log M vir 0.15 log Vmax/V vir Correlations in agreement with previous works (Jeeson-Daniel et al. 2011; Skibba & Maccio 2011) 0.23 log z log c/a 0.03 log λ 0.01 log T log D1, log N neigh log V olch lag V ol vir log V olc lag V ol vir Jose Oñorbe How to Zoom: Lagrange volumes 7

10 Correlations with other halo parameters Correlations in agreement with previous works (Jeeson-Daniel et al. 2011; Skibba & Maccio 2011) Jose Oñorbe How to Zoom: Lagrange volumes 7

11 Correlations with other halo parameters Correlations in agreement with previous works (Jeeson-Daniel et al. 2011; Skibba & Maccio 2011) Only significant correlations with environment parameters ( Lag. vol definitions: for N x,y for D x,y ) Significant dispersion ( with higher Lag. vol. definitions) Jose Oñorbe How to Zoom: Lagrange volumes 7

12 Selecting your halo to zoom How do these numbers translate when you want to zoom? Lagrange volume log V ch,1 vol /Vvir log Mvir (M /h) Virial Mass p.d.f Formation log a50 time log Vmax/Vvir Concentration p.d.f Environment N neight log Mvir (M ) Virial Mass p.d.f Pick smallest Lagrange volumes without biasing any internal halo properties or merger history Jose Oñorbe How to Zoom: Lagrange volumes 8

13 Part II: Let s zoom! Zoom-in simulations resolution: 5123, 10243, 20483, 40963, Lbox : 5, 50, 650 Mpc/h codes: GADGET and ENZO hydro: adiabatic test runs Jose On orbe How to Zoom: Lagrange volumes 9

14 Contamination 10 1st low res particle (r/rvir) level +1 level +2 levels +3 levels +4 levels Lag vol. definition (r/r vir ) For the same halo and fixed Lagrange volume, risk of contamination increases with resolution Jose Oñorbe How to Zoom: Lagrange volumes 10

15 Contamination 10 1st low res particle (r/rvir) level +1 level +2 levels +3 levels +4 levels Lag vol. definition (r/r vir ) For the same halo and fixed Lagrange volume, risk of contamination increases with resolution Recipe to minimize Lagrange volume and guarantee no contamination Jose Oñorbe How to Zoom: Lagrange volumes 10

16 Other Definitions/Codes Convex hull definition Also for ENZO 1st low res particle (r/rvir) level 1 level 1st low res particle (r/rvir) level 1 level 2 levels Lag vol. definition (r/r vir) Lag vol. definition (r/r vir) For the same halo and fixed Lagrange volume, risk of contamination increases with resolution Jose Oñorbe How to Zoom: Lagrange volumes 11

17 Why bother? 10 7 Adiabatic test simulations Gas Density ρ(r) (M /kpc 3 ) T (r) (K) Temperature ρ/ρf 10 0 T/TF r (kpc) r (kpc) Grey lines: L box = 50Mpc/h full box results: Red and orange lines: non-contaminated runs: and Green lines: contaminated runs: and Jose Oñorbe How to Zoom: Lagrange volumes 12

18 Why bother? Adiabatic test simulations Gas Density ρ(r) (M /kpc 3 ) T (r) (K) Temperature ρ/ρf 10 0 T/TF r (kpc) r (kpc) Contaminated density and temperature too low by factors of Jose Oñorbe How to Zoom: Lagrange volumes 12

19 Conclusions There is room to improve the zoom-in technique pipeline, primarily via choosing the Lagrange volume appropriately Halos may be selected with small Lagrange volume without biasing (spin, concentration, formation time, etc) Important to select halos to zoom and save cpu time! Lagrange volume increases with resolution. If you measure Lagrange volume using low-resolution simulations you risk severe contamination in the zoom We have developed recipes to minimize the Lagrange volume (cost) and guarantee no contamination for specific Lagrange volume definitions and codes Jose Oñorbe How to Zoom: Lagrange volumes 13