Exploring star formation using the filaments in the Sloan Digital Sky Survey Data Release Five (SDSS DR5)

TL;DR

This study quantifies the filamentary distribution of galaxies in SDSS DR5, revealing that star-forming galaxies are more filamentary than red galaxies, with high SFR galaxies being more filamentary and associated with dense regions.

Contribution

It provides a detailed analysis of the filamentarity of different galaxy types in SDSS DR5, highlighting the relationship between star formation rates and galaxy distribution structures.

Findings

Star-forming galaxies are more filamentary than red galaxies.

High SFR galaxies are more filamentary than low SFR galaxies.

No significant difference in filamentarity between SF galaxies and AGNs.

Abstract

We have quantified the average filamentarity of the galaxy distribution in seven nearly two dimensional strips from the SDSS DR5 using a volume limited sample in the absolute magnitude range -21 < M_r < -20. The average filamentarity of star forming (SF) galaxies, which are predominantly blue, is found to be more than that of other galaxies which are predominantly red. This difference is possibly an outcome of the fact that blue galaxies have a more filamentary distribution. Comparing the SF galaxies with only the blue other galaxies, we find that the two show nearly equal filamentarity. Separately analyzing the galaxies with high star formation rates (SFR) and low SFR, we find that the latter has a more filamentary distribution. We interpret this in terms of two effects (1.) A correlation between the SFR and individual galaxy properties like luminosity with the high SFR galaxies being more luminous (2.) A relation between the SFR and environmental effects like the density with the high SFR galaxies preferentially occurring in high density regions. These two effects are possibly not independent and are operating simultaneously. We do not find any difference in the filamentarity of SF galaxies and AGNs.