Charla FoF2023 - VPF

Void probability function inside TNg300-1 voids

Friends of Friends Meeting April 2023

Dr. Federico Dávila Kurbán

Is clustering special within voids?

Cosmic

void

void

probability function (VPF)

EMPTY VOLUME in the counts-in-cells statistics

UNDERDENSE REGION in the Cosmic Web

White (1979)

• Most widely used clustering statistic: the 2PCF ξ2
• There is more information encoded in the higher orders ξp; p>=2. But they are difficult to compute.

A pathway to every order of correlation?

void probability function (VPF)

• Count Probability Distribution Function (CPDF), PN(V)
• Void Probability Function: VPF:=P0.

• Why is this interesting?

Sp ≠ Sp(R)

Sp ≠ Sp(t)

Self-similarity

Stable Clustering

White (1979)

VPF

Sp: scaling coefficients

A pathway to every order of correlation?

void probability function (VPF)

• Hierarchical Scaling:

Lognormal

Thermodynamical

Negative Binomial

void probability function (VPF)

Croton et al. (2004)

Fry (1986)

• Reduced VPF (RVPF):

(Basically recepies for Sp)

Hierarchical models

void probability function (VPF)

• Negative Binomial model:

• Thermodynamical model:

Croton et al. (2004): VPF in 2dF survey

Previous Results

vpf

Previous Results

vpf

Croton et al. (2004)

Previous Results

vpf

Croton et al. (2004)

REDSHIFT

REAL

Vogeley et al. (1994): VPF in simulated surveys in real (left) and redshift space (right)

previous results

vpf

There is hierarchical scaling in z-space but not in real space Why?

LDM: Ωm=0.4; h=0.6; b=1.3; σ8=1; λ=0.6

ODM: Ωm=0.4; h=0.5; b=1; σ8=1

CDM1: Ωm=1; h=0.5; b=1.5; σ8=1

previous results

vpf

REDSHIFT Space

REAL Space

S5

S4

S3

Bernardeau et al. (2002)

Review

vpf

• The VPF is a particular case of the distribution of the counts-in-cells
• Hierarchical scaling stems from assuming stable clustering and self-similarity. It is not obvious that it should hold in non-linear scales
• Hierarchical scaling is found in z-space (e.g., Vogeley et al. 1994, Croton et al. 2004, 2006, Conroy et al. 2005)
• This behaviour is not found in real space (e.g., Lahav et al. 1993, Vogeley et al. 1994, Bernardeau et al. 2002)
• The success of the negative binomial model in fitting the distribution of galaxies in z-space is not understood

What do I want to do?

Calculate the VPF inside and outside voids (i.e. randomly throughout the simulation box)

Do the galaxies follow different clustering models in different environments?

Would these behaviours break in real space?

results

Confirms previous results

RVPF throughout tNG300-1

More scatter in Real Space

Dilution test

RVPF throughout tng300-1

results

Real and Z-space VPFs are much more similar inside voids!

RVPF in voids

RVPF in voids

dilution test

results

RVPF

RVPF

Hierarchical scaling inside voids in real space?!

final comparisons

This behavior breaks down in real space, in agreement with previous studies.

VPF in voids

findings

In the redshift space we find hierarchical scaling corresponding to the negative binomial model

In real space we recover the hierarchical scaling (expected for redshift space) within the voids!

Could voids indicate non-gaussianities in the primordial overdensities?

VPF in voids

Implications?

Stable clustering and self-similarity could be valid assumptions inside voids in real space and within the probed ranges?

Maybe clustering is special inside voids?

Wassily Kandinsky (1923)

(Some) References:

• Croton D. J., et al., 2006, Monthly Notices of the Royal Astronomical Society, 379, 1562
• Vogeley M. S., et al., 1994, The Astronomical Journal, 108, 745
• Colombi S., et al., 1994, The Astrophysical Journal Supplement Series, 96, 401
• Conroy C., et al., 2005, The Astrophysical Journal, 635, 990
• Croton D. J., et al., 2004, Monthly Notices of the Royal Astronomical Society, 352, 828

Contact

Thank you!

Dr. Federico Dávila Kurbán

fdavilakurban@unc.edu.ar