Star Formation Properties of Isolated Blue Compact Galaxies

TL;DR

This study investigates the star formation properties of isolated blue compact galaxies in cosmic voids using multi-wavelength data, revealing their star formation rates, histories, and comparison with other dwarf galaxy populations.

Contribution

It provides new insights into the star formation rates and histories of isolated BCGs, combining Hα, SDSS, and 2MASS data with evolutionary models.

Findings

Star formation rates range from 0.1 to 1.0 M_sun/yr, median 0.6.

Colors are best explained by continuous SF plus recent burst.

BCGs have stronger SFRs than Virgo cluster dwarf galaxies.

Abstract

We report H$\alpha$ observations of a sample of very isolated blue compact galaxies (BCGs) located in the direction of large cosmic voids obtained to understand their stellar population compositions, the present star formation (SF) properties, and their star formation histories (SFHs). Our observations were combined with photometric data from the Sloan Digital Sky Survey (SDSS) and near-infrared data from the Two Micron All Sky Survey (2MASS), wherever such data were available. The combined data sets were compared with predictions of evolutionary synthesis models by Bruzual & Charlot (2003a, 2003b). Current star formation rates (SFRs) were determined from the H$\alpha$ measurements, and simplified star formation histories were derived from broad-band and H$\alpha$ photometry and comparisons with the models. We found that the star formation rates range within 0.1--1.0 M$_{\odot}$ yr$^{-1}$, with a median rate of 0.6 M$_{\odot}$ yr$^{-1}$. The observed galaxy colours are better explained by the combination of a continuous SF process with a recent instantaneous SF burst, than by a combination of several instantaneous bursts, as has been suggested previously. We compare our results for the star formation rate of the sample galaxies with that of samples of dwarf galaxies in the Virgo cluster and find that the BCGs have significantly stronger SFRs. The BCGs follow the correlation between H$\alpha$ emission and starlight found for dwarf galaxies in the Virgo Cluster and for other BCGs.