Clustering of K-band selected local galaxies

TL;DR

This study analyzes the clustering properties of a large local galaxy sample selected in the K-band, revealing a power-law correlation function, higher pairwise velocity dispersion than optical samples, and limitations of semi-analytical models in reproducing observed velocities.

Contribution

It provides a detailed clustering analysis of K-band selected galaxies, including measurements of correlation functions and velocity dispersions, and compares observations with semi-analytical models.

Findings

Correlation function follows a power law with specific parameters.

Pairwise velocity dispersion is larger than in optical samples.

Semi-analytical models do not fully reproduce observed velocity dispersions.

Abstract

We present detailed clustering analysis of a large K-band selected local galaxy sample, which is constructed from the 2MASS and the SDSS and consists of $82,486$ galaxies with $10 < K < 13.5$ and $0.01 < z < 0.1$. The two-point correlation function of the magnitude-limited sample in real space at small scales is well described by a power law $\xi(r)=(r/6.44\pm0.23)^{-1.81\pm0.02}$. The pairwise velocity dispersion is derived from the anisotropic two-point correlation function and find the dispersion $\sigma_{12}=685\pm 17\kms$ if its scale invariance is assumed, which is larger than values measured in optical bands selected galaxy samples. We further investigate the dependence of the two-point correlation function and the $\sigma_{12}$ on the $g-r$ color and the $K$-band luminosity, obtain similar results to previous works in optical bands. Comparing a mock galaxy sample with our real data indicates that the semi-analytical model can not mimic the $\sigma_{12}$ in observation albeit it can approximate the two-point correlation function within measurement uncertainties.