Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at $1.5 < z < 6.4$

TL;DR

This study analyzes a large sample of 2052 galaxies at redshifts 1.5 to 6.4 using MUSE data, focusing on rest-frame UV emission lines to understand galaxy properties and their evolution in the early universe.

Contribution

It provides a comprehensive catalog of UV emission lines in high-redshift galaxies and explores their connection to galaxy physical parameters, including ionization and metallicity.

Findings

Detection efficiency of UV lines increases with survey depth.

UV line strength correlates with Ciii] emission.

UV emitters have ionization parameter log10(U) ≈ -2.5 and metallicity around 0.66 Z⊙.

Abstract

[Abbreviated] Rest-frame UV emission lines probe physical parameters of the emitting star-forming galaxies and their environments. The strongest main UV line, Ly$\alpha$, has been instrumental in advancing the general knowledge of galaxy formation in the early universe. However, observing Ly$\alpha$ emission becomes increasingly challenging at $z \gtrsim 6$ when the neutral hydrogen fraction of the CGM and IGM increases. Secondary weaker UV emission lines provide important alternative methods for studying galaxy properties at high redshift. We present a large sample of rest-frame UV emission line sources at intermediate redshift for calibrating and exploring the connection between secondary UV lines and the emitting galaxies' physical properties and their Ly$\alpha$ emission. The sample of 2052 emission line sources with $1.5 < z < 6.4$ was selected through untargeted source detection in three-dimensional MUSE data cubes. We searched optimally extracted 1D spectra of the full sample for UV emission features via emission line template matching, resulting in a sample of more than 100 rest-frame UV emission line detections. We show that the detection efficiency of (non-Ly$\alpha$) UV emission lines increases with survey depth, and that the UV emission line strength often correlate with the strength of Ciii]. We measured the velocity offsets of resonant emission lines with respect to systemic tracers as well as the electron density and the gas-phase abundance. Lastly, using "PhotoIonization Model Probability Density Functions" we find that the UV line emitters generally have ionization parameter log10(U) $\approx$ -2.5 and metal mass fractions that scatter around Z $\approx$ 10$^{-2}$, that is Z $\approx$ 0.66Z$\odot$. Value-added catalogs of the full sample of MUSE objects studied in this work and a collection of UV line emitters from the literature are provided with this paper.