The Effect of Environment on Type Ia Supernovae in the Dark Energy Survey Three-Year Cosmological Sample
Creators: name: Kelsey, L.
name: Sullivan, M.
name: Smith, M.
name: Wiseman, P.
name: Brout, D.
name: Davis, T. M.
name: Frohmaier, C.
name: Galbany, L.
name: Grayling, M.
name: Gutiérrez, C. P.
name: Hinton, S. R.
name: Kessler, R.
name: Lidman, C.
name: Möller, A.
name: Sako, M.
name: Scolnic, D.
name: Uddin, S. A.
name: Vincenzi, M.
name: Abbott, T. M. C.
name: Aguena, M.
name: Allam, S.
name: Annis, J.
name: Avila, S.
name: Bacon, D.
name: Bertin, E.
name: Brooks, D.
name: Burke, D. L.
name: Rosell, A. Carnero
name: Kind, M. Carrasco
name: Carretero, J.
name: Castander, F. J.
name: Costanzi, M.
name: da Costa, L. N.
name: Desai, S.
name: Diehl, H. T.
name: Doel, P.
name: Everett, S.
name: Ferrero, I.
name: Ferté, A.
name: Flaugher, B.
name: Fosalba, P.
name: García-Bellido, J.
name: Gerdes, D. W.
name: Gruen, D.
name: Gruendl, R. A.
name: Gschwend, J.
name: Gutierrez, G.
name: Hollowood, D. L.
name: Honscheid, K.
name: James, D. J.
name: Kim, A. G.
name: Kuehn, K.
name: Kuropatkin, N.
name: Lahav, O.
name: Lima, M.
name: Marshall, J. L.
name: Martini, P.
name: Menanteau, F.
name: Miquel, R.
name: Morgan, R.
name: Ogando, R. L. C.
name: Palmese, A.
name: Paz-Chinchón, F.
name: Plazas, A. A.
name: Romer, A. K.
name: Sánchez, C.
name: Sanchez, E.
name: Serrano, S.
name: Sevilla-Noarbe, I.
name: Suchyta, E.
name: Tarle, G.
name: Thomas, D.
name: To, C.
name: Varga, T. N.
name: Walker, A. R.
name: Wilkinson, R. D.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Analyses of type Ia supernovae (SNe Ia) have found puzzling correlations between their standardised luminosities and host galaxy properties: SNe Ia in high-mass, passive hosts appear brighter than those in lower-mass, star-forming hosts. We examine the host galaxies of SNe Ia in the Dark Energy Survey three-year spectroscopically-confirmed cosmological sample, obtaining photometry in a series of "local" apertures centred on the SN, and for the global host galaxy. We study the differences in these host galaxy properties, such as stellar mass and rest-frame $U-R$ colours, and their correlations with SN Ia parameters including Hubble residuals. We find all Hubble residual steps to be $&gt;3σ$ in significance, both for splitting at the traditional environmental property sample median and for the step of maximum significance. For stellar mass, we find a maximal local step of $0.098\pm0.018$ mag; $\sim 0.03$ mag greater than the largest global stellar mass step in our sample ($0.070 \pm 0.017$ mag). When splitting at the sample median, differences between local and global $U-R$ steps are small, both $\sim 0.08$ mag, but are more significant than the global stellar mass step ($0.057\pm0.017$ mag). We split the data into sub-samples based on SN Ia light curve parameters: stretch ($x_1$) and colour ($c$), finding that redder objects ($c &gt; 0$) have larger Hubble residual steps, for both stellar mass and $U-R$, for both local and global measurements, of $\sim0.14$ mag. Additionally, the bluer (star-forming) local environments host a more homogeneous SN Ia sample, with local $U-R$ r.m.s. scatter as low as $0.084 \pm 0.017$ mag for blue ($c &lt; 0$) SNe Ia in locally blue $U-R$ environments.
description: 18 pages, 11 figures. Accepted for publication in MNRAS