# Star-forming Galaxies in Intermediate Redshift Clusters: Stellar vs. Dynamical Masses of Luminous Compact Blue Galaxies

**Authors:** S. M. Randriamampandry, S. M. Crawford, M. A. Bershady, G. D. Wirth, C. M. Cress  
**arXiv:** [1706.04534](https://arxiv.org/abs/1706.04534)  
**Date:** 2017-06-14  
**Summary page:** https://www.summarizepaper.com/en/paper/1706.04534v1/

## Key points

- The study investigates the stellar masses of Luminous Compact Blue Galaxies (LCBGs) in the distant cluster MS$~$0451.6-0305 at a redshift of approximately $z\approx0.54$
- 16 spectroscopically-confirmed cluster LCBGs were analyzed using ground-based multicolor imaging and spectroscopy
- Stellar masses were determined using spectral energy distribution (SED) models fitted to multiband photometry
- Comparison was made between the stellar masses derived from SED models and dynamical masses obtained from emission-line spectra
- Correlations were found between stellar age, extinction, and stellar mass derived from different SED models
- Cluster LCBGs exhibit lower dynamical-to-stellar mass ratios compared to field LCBG counterparts
- Specific star formation rate declines steeply with increasing mass among cluster LCBGs, suggesting vigorous star formation activity

## Summary

In this study, the authors investigate the stellar masses of a specific class of star-forming objects called Luminous Compact Blue Galaxies (LCBGs). They focus on a sample of galaxies in the distant cluster MS$~$0451.6-0305 at a redshift of approximately $z\approx0.54$. The researchers utilize ground-based multicolor imaging and spectroscopy to analyze 16 spectroscopically-confirmed cluster LCBGs that meet certain criteria, including color ($B-V < 0.5$), surface brightness ($\mu_B < 21$ mag arcsec$^{-2}$), and magnitude ($M_B < -18.5$). To determine the stellar masses of these LCBGs, they employ spectral energy distribution (SED) models fitted to multiband photometry. They compare these measurements with dynamical masses previously obtained from emission-line spectra, which were determined based on velocity dispersion between 10 $< \sigma_v (\rm km~ s^{-1}) < 80$. The study compares two different stellar population models that estimate stellar mass in starbursting galaxies. The results reveal correlations between the stellar age, extinction, and stellar mass derived from these two distinct SED models. The analysis shows that the stellar masses of cluster LCBGs are distributed similarly to those of field LCBGs. However, there is an interesting difference: the cluster LCBGs exhibit lower dynamical-to-stellar mass ratios ($\rm M_{dyn}/M_{\ast} = 2.6$) compared to their field LCBG counterparts ($\rm M_{dyn}/M_{\ast}=4.8$). This finding echoes trends observed in low-redshift dwarf elliptical galaxies. Moreover, within this limited sample it is noted that the specific star formation rate declines steeply with increasing mass among the cluster LCBGs; suggesting that these galaxies have undergone vigorous star formation activity. Overall, this study provides valuable insights into the stellar masses of LCBGs in intermediate redshift clusters and contributes to our understanding of the relationship between stellar mass, dynamical mass and star formation activity in these galaxies.