Alignment of interacting haloes in the Horizon Run 4 simulation - - PowerPoint PPT Presentation

Alignment of interacting haloes in the Horizon Run 4 simulation

L’Huillier, Park & Kim MNRAS submitted

Benjamin L’Huillier (KIAS → KASI)

with Changbom Park, Juhan Kim (KIAS)

XIIth Rencontres du Vietnam, ICSE, Quy Nhon

Model-independent measurement of H0

L’Huillier & Shafieloo, arXiv:1606.06832

60 65 70 75 80 H0(kms−1Mpc−1) LOWZ 60 65 70 75 80 H0(kms−1Mpc−1) CMASS

H(z)/h(z) c/(1 + z)D(z)/dA(z)

H0 = H(z)

h(z)

H0 =

c 1+z D(z) dA(z)

H(z), dA(z) from BAO (BOSS, Cuesta et al 2016) h(z) = 1/D′(z), D(z): model-independently reconstructed from supernovae (JLA, Betoule et al 2014)

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 2 / 14

Outline

1

Motivations

2

Simulation and Method

3

Alignment of the major axes of interacting pairs

4

Summary and perspectives

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 3 / 14

Motivations

Galaxies form within the cosmic web: properties must be related to their environment The study of the alignment of the spins and shapes of haloes can shed light

• n galaxy formation within their environments

Alignment as a probe of the large-scale structures Intrinsic alignment: source of systematics for weak lensing analysis From simulations: spins aligned with the intermediate axis of the tidal tensor Wang et al (2011) mass dependence: low-mass (massive) haloes have their spin parallel (orthogonal) to filaments Hahn et al (2007), Haloes in sheets have their spin in the plane

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 4 / 14

The Horizon Run 4 simulation

Horizon Run 4 (J. Kim et al 2015, JKAS)

N-body: L = 3.15 h−1Gpc, N = 63003 (¯ d = 0.5 h−1Mpc), WMAP5 cosmology 8000 CPU cores, 2000 timesteps, 50 days at KISTI (Korea).

Catalogues

Haloes detected with OPFOF, and subhaloes with PSB Minimum subhalo mass (20 particles): 1.8 × 1011 h−1M⊙ Target (MT > 5 × 1011 h−1M⊙) and neighbour (MN > 2 × 1011 h−1M⊙) catalogues Hereafter, “haloes” refer to PSB subhaloes (↔ galaxies)

Interactions

A target T is interacting if it is located with the virial radius of its neighbour N MN> 0.4 MT At z = 0: NTarget = 225 406 978; Ninteractions = 14 267 922

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 5 / 14

Large-scale density

• B. L’Huillier, C. Park and J. Kim 2015, MNRAS 451, 527

To quantify the environment: ρ20: density over 20 neighbours ρ20 =

20

• i=1

MiW (ri, h), where ri is the distance to the ith neighbour, Mi its mass, W the SPH spline kernel, and h the smoothing length. Normalisation by ¯ ρ =

N Mi:

1 + δ = ρ20/¯ ρ

50 100 150 x (h−1 Mpc) 50 100 150 y (h−1 Mpc) z =0 50 100 150 x (h−1 Mpc) 50 100 150 y (h−1 Mpc) z =1

All haloes 10 <1 +δ <30 1 +δ >100

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 6 / 14

Method

• B. L’Huillier, C. Park & J. Kim MNRAS submitted

To detect an alignment signal of an angle θ = (u, v) , following Yang et al 2006, we used the normalised pair count: Count the number of pairs N(θ) with angle θ for Nrand ≃ 200, calculate

• NR(θ)
• and σθ the mean and std deviation of

random permutations of u. We look at f (θ) = N(θ)/

• NR(θ)
• If f ≡ 1: No alignment (random)

If f (cos θ ≃ ±1) ≫ 1 : Alignment (parallel/anti parallel) If f (cos θ ≃ 0) ≫ 1: Anti-alignment (orthogonal) the strength of the signal (error bars) is given by σθ/

• NR(θ)
• .

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 7 / 14

Shapes

T N γ ε aT aN r γ = (aT, r): angle between major axis (target) and direction neighbour ε = (aN, r): angle major between the major axis of the neighbour and the direction

• f the target

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 8 / 14

Dependence on mass and environment

0.0 0.2 0.4 0.6 0.8 1.0

cosγ

10-2 10-1 100 101

f(cosγ)

• 5. 00 × 1011h −1M ⊙ < MT
• 1. 53 × 1012h −1M ⊙
• 1. 53 × 1012h −1M ⊙ < MT
• 4. 68 × 1012h −1M ⊙
• 4. 68 × 1012h −1M ⊙ < MT
• 1. 43 × 1013h −1M ⊙
• 1. 43 × 1013h −1M ⊙ < MT
• 4. 39 × 1013h −1M ⊙
• 4. 39 × 1013h −1M ⊙ < MT
• 1. 34 × 1014h −1M ⊙
• 1. 34 × 1014h −1M ⊙ < MT
• 1. 34 × 1014h −1M ⊙

0.0 0.2 0.4 0.6 0.8 1.0

cosγ

• 0. 02 < 1 + δ
• 0. 21
• 0. 21 < 1 + δ
• 2. 27
• 2. 27 < 1 + δ
• 24. 13
• 24. 13 < 1 + δ
• 256. 92
• 256. 92 < 1 + δ
• 2735. 15
• 2735. 15 < 1 + δ
• 29118. 66
• 29118. 66 < 1 + δ
• 310000. 00

z = 0

Mass Density γ = (aT, r); qT < 0.8

Alignment increase with mass; little density dependence Major axis aligned with the direction of the neighbour

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 9 / 14

10-1 100 101

f(cosγ) δ < ∆1(z) ∆1(z) < δ < ∆2(z) δ > ∆2(z)

10-1 100 101

f(cosγ)

0.2 0.4 0.6 0.8

cosγ

10-1 100 101

f(cosγ)

z = 4.0 z = 3.1 z = 2.0 0.2 0.4 0.6 0.8

cosγ

z = 1.5 z = 1.0 0.2 0.4 0.6 0.8

cosγ

z = 0.5 z = 0.0 M0(z) < M < M1(z) M1(z) < M < M2(z) M > M2(z)

Higher densities Higher masses

γ = (aT, r); qT < 0.8

Alignment stronger at low-δ and low-z; little mass dependence Major axis aligned with the direction of the neighbour

Alignment of prolate pairs

0° 45° 90° 135° 180° 225° 270° 315° γ

z = 0.0

0° 45° 90° 135° 180° 225° 270° 315° γ

z = 1.0

γ = (aT, r); ε = (aN, r);

Neighbours are drawn at their angular position γ proportionaly to P(γ). Neighbours located in the direction of the major axis Neighbours point toward the Target

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 11 / 14

Alignment of prolate pairs

0° 45° 90° 135° 180° 225° 270° 315° γ

z = 0.0

0° 45° 90° 135° 180° 225° 270° 315° γ

z = 1.0

10-1 100 101 PDF z = 0

0.00 < p < 0.66

γ = 8.1 ◦ γ = 59.3 ◦ γ = 89.4 ◦ z = 0

0.85 < p < 1.00

γ = 8.1 ◦ γ = 59.3 ◦ γ = 89.4 ◦ 0.0 0.2 0.4 0.6 0.8 cosǫ 10-1 100 101 PDF z = 1 0.0 0.2 0.4 0.6 0.8 cosǫ z = 1

γ = (aT, r); ε = (aN, r);

Neighbours are drawn at their angular position γ proportionaly to P(γ). Neighbours located in the direction of the major axis Neighbours point toward the Target

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 11 / 14

Spins

T N φ JT α JN r α = (JT, r): angle between spin target and direction neighbour φ = (JT, JN): angle between target and neighbour neighbour spins

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 12 / 14

0.5 1.0 1.5 2.0 2.5

f(cosφ) δ < ∆1(z) ∆1(z) < δ < ∆2(z) δ > ∆2(z)

0.5 1.0 1.5 2.0 2.5

f(cosφ)

0.5 0.0 0.5

cosφ

0.5 1.0 1.5 2.0 2.5

f(cosφ)

z = 4.0 z = 3.1 z = 2.0 0.5 0.0 0.5

cosφ

z = 1.5 z = 1.0 0.5 0.0 0.5

cosφ

z = 0.5 z = 0.0 M0(z) < M < M1(z) M1(z) < M < M2(z) M > M2(z)

Higher densities Higher masses

φ = (JT, JN)

At high-z: anti-parallel or no alignment At low-z: aligned

Summary and perspective

The unprecedented statistics of HR4 enable us to study the alignment as a function

• f the environment

The angular position neighbour is aligned with the major axis of the target Alignment increases with mass, independent of large-scale density Alignment signal stronger at low redshift Flip in the spin alignemtn at z ≃ 2 Compare with observations: need for hydro simulations

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 14 / 14

Summary and perspective

The unprecedented statistics of HR4 enable us to study the alignment as a function

• f the environment

The angular position neighbour is aligned with the major axis of the target Alignment increases with mass, independent of large-scale density Alignment signal stronger at low redshift Flip in the spin alignemtn at z ≃ 2 Compare with observations: need for hydro simulations

Cảm ơn!

Benjamin L’Huillier (KASI) Halo interactions Quy Nhon, 2016–01-11 14 / 14