[Paper Review] Environmental dependence of galaxy age in the Main galaxy sample of SDSS DR10

Xin‐Fa Deng|arXiv (Cornell University)|Jun 1, 2014

Galaxies: Formation, Evolution, Phenomena3 citations

TL;DR

This study analyzes the environmental dependence of galaxy age using two volume-limited Main galaxy samples from SDSS DR10, revealing that older galaxies preferentially reside in dense regions, while younger galaxies are found in low-density environments. The age-density relation is primarily driven by the combined effects of the age-stellar mass and stellar mass-density relations.

ABSTRACT

Using two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10), I investigate the environmental dependence of galaxy age, and get the same conclusions in two volume-limited Main galaxy samples: old galaxies exist preferentially in the densest regions of the universe, while young galaxies are located preferentially in low density regions. Such an age-density relation is likely a combination of a strong age-stellar mass relation and the stellar mass-density relation.

Motivation & Objective

• To investigate how galaxy age correlates with large-scale environmental density in the local universe.
• To determine whether the observed age-environment relation is driven by intrinsic galaxy properties or environmental effects.
• To assess the role of stellar mass in mediating the age-density relation in galaxy populations.
• To validate the robustness of the age-environment trend across independent, volume-limited samples.

Proposed method

• Construction of two volume-limited Main galaxy samples from SDSS DR10 to minimize selection biases.
• Measurement of galaxy ages using stellar population synthesis models applied to photometric and spectroscopic data.
• Quantification of local environmental density via the local galaxy number density around each galaxy.
• Statistical analysis of the age-density relation, controlling for stellar mass to isolate environmental effects.
• Comparison of results across two independent volume-limited samples to ensure consistency.

Experimental results

Research questions

• RQ1 Is there a significant correlation between galaxy age and local environmental density in the local universe?
• RQ2 To what extent is the age-density relation driven by the stellar mass of galaxies?
• RQ3 How does the age-density relation compare across different volume-limited samples of the same survey?
• RQ4 What is the relative contribution of the age-stellar mass and stellar mass-density relations to the observed environmental dependence of galaxy age?

Key findings

• Older galaxies are found preferentially in the densest regions of the universe, while younger galaxies are located in low-density environments.
• The age-density relation is strongly correlated with the stellar mass-density relation, indicating environmental effects are mediated through mass.
• The age-stellar mass relation plays a dominant role in shaping the observed age-environment trend.
• The same environmental dependence of galaxy age is consistently observed across two independent volume-limited Main galaxy samples from SDSS DR10.