The VIRUS-P Exploration of Nearby Galaxies (VENGA): Survey Design, Data Processing, and Spectral Analysis Methods

TL;DR

VENGA is an integral field spectroscopic survey of 30 nearby spiral galaxies, providing detailed 2D maps of various physical properties to study galaxy evolution.

Contribution

This paper introduces the survey design, data reduction, and spectral analysis methods for VENGA, including a new inclination measurement technique for face-on galaxies.

Findings

High-quality data-cubes for 30 galaxies with detailed spectral information.

Successful application of spectral fitting to derive stellar and gas kinematics.

Demonstration of a new inclination measurement method for face-on systems.

Abstract

We present the survey design, data reduction, and spectral fitting pipeline for the VIRUS-P Exploration of Nearby Galaxies (VENGA). VENGA is an integral field spectroscopic survey, which maps the disks of 30 nearby spiral galaxies. Targets span a wide range in Hubble type, star formation activity, morphology, and inclination. The VENGA data-cubes have 5.6'' FWHM spatial resolution, ~5A FWHM spectral resolution, sample the 3600A-6800A range, and cover large areas typically sampling galaxies out to ~0.7 R_25. These data-cubes can be used to produce 2D maps of the star formation rate, dust extinction, electron density, stellar population parameters, the kinematics and chemical abundances of both stars and ionized gas, and other physical quantities derived from the fitting of the stellar spectrum and the measurement of nebular emission lines. To exemplify our methods and the quality of the data, we present the VENGA data-cube on the face-on Sc galaxy NGC 628 (a.k.a. M 74). The VENGA observations of NGC 628 are described, as well as the construction of the data-cube, our spectral fitting method, and the fitting of the stellar and ionized gas velocity fields. We also propose a new method to measure the inclination of nearly face-on systems based on the matching of the stellar and gas rotation curves using asymmetric drift corrections. VENGA will measure relevant physical parameters across different environments within these galaxies, allowing a series of studies on star formation, structure assembly, stellar populations, chemical evolution, galactic feedback, nuclear activity, and the properties of the interstellar medium in massive disk galaxies.