The Ultraviolet Deep Imaging Survey of Galaxies in the Bootes Void I: catalog, color-magnitude relations and star formation

TL;DR

This study presents a deep ultraviolet imaging survey of galaxies in the Bootes Void, cataloging six star-forming galaxies, analyzing their properties, and exploring their star formation rates and color-magnitude relations.

Contribution

It provides the first detailed UV survey of Bootes Void galaxies, including new detections and analysis of their star formation and color-magnitude relations.

Findings

Six star-forming galaxies identified in the void.

Most galaxies are fainter and less massive than L* galaxies.

Star formation rates range from 0.05 to 51.01 M_sun/yr, median 3.96.

Abstract

We present a deep far and near-ultraviolet (FUV and NUV) wide-field imaging survey of galaxies in the Bootes Void using Ultra-Violet Imaging Telescope onboard {\em AstroSat}. Our data reach $5\sigma$ limiting magnitudes for point sources at 23.0 and 24.0 AB mag in FUV and NUV respectively. We report a total of six star-forming galaxies residing in the Bootes Void alongside the full catalog, and of these, three are newly detected in our FUV observation. Our void galaxy sample spans a range of UV colors $(-0.35\, \leq$ FUV$-$NUV $\leq\, 0.68)$ and absolute magnitudes $(-14.16\, \leq\, \mathrm{M_{NUV}}\, \leq\, -18.65)$. In addition, {\em Sloan Digital Sky Survey} and {\em Two-micron All Sky Survey} archival data are being used to study UV, optical, and infrared color-magnitude relations for our galaxies in the void. We investigate the nature of bi-modal color distribution, morphologies, and star formation of the void galaxies. Most of the galaxies in our sample are fainter and less massive than L$^{\ast}$ galaxies, with M$_\mathrm{r} > -20$. Our analysis reveals a dominant fraction of bluer galaxies over the red ones in the void region probed. The internal and Galactic extinction corrected FUV star formation rates (SFRs) in our void galaxy catalog varies in a large range of $0.05$ to $51.01$ M$_{\odot} yr^{-1}$, with a median $3.96$ M$_{\odot} yr^{-1}$. We find a weak effect of the environment on the SFRs of galaxies. Implications of our findings are discussed.