Modeling Galaxy-Galaxy Weak Lensing with SDSS Groups

TL;DR

This study models galaxy-galaxy weak lensing signals using SDSS data and compares predictions with observations, confirming consistency with a specific cosmological model and exploring various galaxy and halo properties.

Contribution

It provides a detailed model of galaxy-galaxy lensing signals incorporating galaxy types and halo characteristics, validated against SDSS observations.

Findings

Model predictions align with SDSS data under WMAP 3-year cosmology.

Higher sigma_8 models over-predict lensing signals.

Different galaxy and halo properties significantly affect lensing predictions.

Abstract

We use galaxy groups selected from the Sloan Digital Sky Survey (SDSS) together with mass models for individual groups to study the galaxy-galaxy lensing signals expected from galaxies of different luminosities and morphological types. We compare our model predictions with the observational results obtained from the SDSS by Mandelbaum et al. (2006) for the same samples of galaxies. The observational results are well reproduced in a $\Lambda$CDM model based on the WMAP 3-year data, but a $\Lambda$CDM model with higher $\sigma_8$, such as the one based on the WMAP 1-year data,significantly over-predicts the galaxy-galaxy lensing signal. We model, separately, the contributions to the galaxy-galaxy lensing signals from different galaxies: central versus satellite, early-type versus late-type, and galaxies in halos of different masses. We also examine how the predicted galaxy-galaxy lensing signal depends on the shape, density profile, and the location of the central galaxy with respect to its host halo.