Wolf-Rayet galaxies in SDSS-IV MaNGA. I. Catalog construction and sample properties

TL;DR

This study constructs a catalog of 267 Wolf-Rayet regions in 90 galaxies using SDSS-IV MaNGA data, revealing their association with star-forming, late-type, and interacting galaxies, and providing insights into their detection rates and properties.

Contribution

The paper presents the first extensive catalog of WR regions identified through spatially resolved spectroscopy in MaNGA, improving detection rates over previous surveys and analyzing their host galaxy characteristics.

Findings

WR regions are found in 90 galaxies, mostly late-type and interacting.

Detection rate of WR galaxies is about 2%, higher than previous single-fiber studies.

WR regions are associated with bluer, high star formation rate galaxies.

Abstract

Wolf-Rayet (WR) galaxies are a rare population of galaxies that host living high-mass stars during their WR phase (i.e. WR stars) and are thus expected to provide interesting constraints on the stellar Initial Mass Function, massive star formation, stellar evolution models, etc. Spatially resolved spectroscopy should in principle provide a more efficient way of identifying WR galaxies than single-fiber surveys of galactic centers such as SDSS-I & II, as WR stars should be more preferentially found in discs. Using IFU data from the ongoing SDSS-IV MaNGA survey, we have performed a thorough search for WR galaxies. We first identify H II regions in each datacube and carry out full spectral fitting to the stacked spectra. We then visually inspect the residual spectrum of each H II region and identify WR regions that present a significant "blue bump" at 4600-4750 A. The resulting WR catalog includes 267 WR regions of ~500pc (radius) sizes, distributed in 90 galaxies from the current sample of MaNGA (MaNGA Product Launch 7). We find WR regions are exclusively found in galaxies that show bluest colors and highest star formation rates for their mass. Most WR galaxies have late-type morphologies and show relatively large asymmetry in their images, implying that WR regions are more preferentially found in interacting/merging galaxies. We estimate the stellar mass function of WR galaxies and the mass-dependent detection rate. The detection rate of WR galaxies is typically ~2%, with weak dependence on stellar mass. This detection rate is about 40 times higher than previous studies with SDSS single fiber data, and by a factor of 2 lower than the CALIFA-based WR catalog. We make comparisons with SDSS and CALIFA studies, and conclude that different detection rates can be explained mainly by three factors: spatial coverage, spectral signal-to-noise ratio, and redshift ranges of the parent sample.