THE VIRUS-P EXPLORATION OF NEARBY GALAXIES (VENGA): SURVEY DESIGN, DATA PROCESSING, AND SPECTRAL ANALYSIS METHODS

Abstract

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