Galaxy Rest-Frame UV Colors at z ~ 2-4 with HST UVCANDELS

• Published in: arXiv.org 2024-05
• Main Authors: Morales, Alexa, Finkelstein, Steven, Bagley, Micaela, Alavi, Anahita, Grogin, Norman, Hathi, Nimish, Koekemoer, Anton, Kalina Nedkova, Prichard, Laura, Rafelski, Marc, Sunnquist, Ben, Taamoli, Sina, Teplitz, Harry, Wang, Xin, Windhorst, Rogier, Yung, L Y Aaron
• Format: Article
• Language: English
• Subjects: Correlation; Cosmic dust; Galaxy distribution; Parameters; Photometry; Red shift; Spectral energy distribution; Star & galaxy formation; Star formation rate; Stars & galaxies; Stellar mass
• ISSN: 2331-8422

We present an analysis of rest-frame UV colors of 17,243 galaxies at \(z\sim2-4\) in the HST UVCANDELS fields: GOODS-N, GOODS-S, COSMOS, and EGS. Here, we study the rest-frame UV spectral slope, \(\beta\), measured via model spectra obtained via spectral energy distribution (SED) fitting, \(\beta_{SED}\), and explore its correlation with various galaxy parameters (photometric redshift, UV magnitude, stellar mass, dust attenuation, star formation rate [SFR], and specific SFR) obtained via SED fitting with Dense Basis. We also obtain measurements for \(\beta\) via photometric power-law fitting and compare them to our SED-fit-based results, finding good agreement on average. While we find little evolution in \(\beta\) with redshift from \(z=2-4\) for the full population, there are clear correlations between \(\beta\) (and related parameters) when binned by stellar mass. For this sample, lower stellar mass galaxies (log[\(M_*\)] = 7.5-8.5 \(M_\odot\)) are typically bluer (\(\beta_{SED}=-2.0\pm 0.2\) / \(\beta_{PL} = -2.1\pm0.4\)), fainter (\(MUV = -17.8^{+0.7}_{-0.6}\)) less dusty (\(A{v}=0.4\pm0.1\) mag), exhibit lower rates of star formation (log[SFR]=\(0.1\pm0.2 M_\odot/\) yr) and higher specific star formation rates (log[sSFR]=\(-8.2\pm0.2 \ \mathrm{yr}^{-1}\)) than their high-mass counterparts. Higher-mass galaxies (log[\(M_*\)] \(=10.0-12.0 \ M_\odot\)) are on average redder (\(\beta_{SED}=-0.9^{+0.8}_{-0.5}\) / \(\beta_{PL}=-1.0^{+0.8}_{-0.5}\)), brighter (\(MUV=-19.6^{+1.0}_{-1.2}\)), dustier (\(Av = 0.9^{+0.5}_{-0.4}\) mag), have higher SFRs (log[SFR]=\(1.2^{+0.6}_{-1.1} M_\odot\) yr), and lower sSFRs (log[sSFR]=\(-9.1^{+0.5}_{-1.1} {yr}^{-1}\)). This study's substantial sample size provides a benchmark for demonstrating that the rest-frame UV spectral slope correlates with stellar mass-dependent galaxy characteristics at \(z\sim2-4\), a relationship less discernible with smaller datasets typically available at higher redshifts.