An Atlas of Star-Forming Galaxy Equivalent Widths

TL;DR

This paper provides a comprehensive atlas of emission line equivalent widths for starburst galaxies, combining models from Starburst99 and Cloudy to aid in interpreting starburst galaxy spectra, especially for JWST observations.

Contribution

It introduces a detailed grid of photoionization models covering a wide range of physical conditions, linking spectral energy distributions with emission line diagnostics.

Findings

C IV λ1549 predicted as a key diagnostic line for star formation.

Atlas covers 96 emission lines across diverse galaxy conditions.

Models useful for analyzing local and high-redshift starburst galaxies.

Abstract

We present an atlas of starburst galaxy emission lines spanning 10 orders of magnitude in ionizing flux and 7 orders of magnitude in hydrogen number density. Coupling SEDs from Starburst99 with photoionization calculations from Cloudy, we track 96 emission lines from 977 {\AA} to 205 m which are common to nebular regions, have been observed in H II regions, and serve as useful diagnostic lines. Each simulation grid displays equivalent widths and contains ~1.5x10$^4$ photoionization models calculated by supplying a spectral energy distribution, chemical abundances, dust content, and gas metallicity (ranging from 0.2 Z$\odot$ to 5.0 Z$\odot$). Our simulations will prove useful in starburst emission line data analysis, especially regarding local starburst galaxies that show high ionization emission lines. One sample application of our atlas predicts that C IV $\lambda$1549 will serve as a useful diagnostic emission line of vigorous star formation for coming James Webb Space Telescope observations predicting a peak equivalent width of approximately 316 {\AA}.