Virgo Filaments VI: H$\alpha$ clumps in the filaments around the Virgo galaxy cluster

TL;DR

This study analyzes H-alpha emission in 685 Virgo cluster galaxies to understand environmental effects on star formation, revealing a fractal pattern in clump distribution and slight peripheral differences in filament galaxies.

Contribution

It introduces a pipeline for decomposing H-alpha images into star-forming clumps and compares filament and non-filament galaxies accounting for observational biases.

Findings

Clump number and size depend on galaxy distance and resolution.

Star-forming regions follow a fractal distribution pattern.

Filament galaxies have marginally more peripheral clumps.

Abstract

It is still not clear which environmental processes operate in filaments. Given the ubiquity of filaments and their importance in feeding clusters, a proper understanding of these mechanisms is crucial to a more complete picture of galaxy evolution. To investigate them, we need large galaxy samples with spatially resolved information. As part of this effort, we analyse resolved H$\alpha$ maps of 685 galaxies inside and outside the filaments around the Virgo cluster in addition to extensive measurements of integrated physical properties. We create a pipeline to decompose the H$\alpha$ images into individual clumps that trace star forming regions. We find that the number and average size of clumps in a galaxy are well-defined functions of distance and angular resolution. In particular, the power-law relation between the number of clumps and the distance of a galaxy is consistent with a fractal structure of star forming regions. We formulate an algorithm to compare filament and non-filament galaxies after removing observational differences. Although we do not have any conclusive evidence for a difference in clump size distributions between filament and non-filament galaxies, we do find that filament galaxies have slightly more peripheral clumps than their non-filament counterparts.