Core-collapse supernovae and host galaxy stellar populations

Abstract

We have used images and spectra of the Sloan Digital Sky Survey to examine the host galaxies of 519 nearby supernovae (SN). The colors at the sites of the explosions, as well as chemical abundances, and specific star formation rates (SFRs) of the host galaxies provide circumstantial evidence on the origin of each SNtype. We examine separately SNII, SNIIn, SNIIb, SNIb, SNIc, and SNIc with broad lines (SNIc-BL). For host galaxies that have multiple spectroscopic fibers, we select the fiber with host radial offset most similar to that of the SN. TypeIc SN explode at small host offsets, and their hosts have exceptionally strongly star-forming, metal-rich, and dusty stellar populations near their centers. The SNIc-BL and SNIIb explode in exceptionally blue locations, and, in our sample, we find that the host spectra for SNIc-BL show lower average oxygen abundances than those for SNIc. SNIIb host fiber spectra are also more metal-poor than those for SNIb, although a significant difference exists for only one of two strong-line diagnostics. SNIc-BL host galaxy emission lines show strong central specific SFRs. In contrast, we find no strong evidence for different environments for SNIIn compared to the sites of SNII. Because our SNsample is constructed from a variety of sources, there is always a risk that sampling methods can produce misleading results. We have separated the SN discovered by targeted surveys from those discovered by galaxy-impartial searches to examine these questions and show that our results do not depend sensitively on the discovery technique. © 2012. The American Astronomical Society. All rights reserved.