First Cosmology Results using Type Ia Supernovae from the Dark Energy Survey: The Effect of Host Galaxy Properties on Supernova Luminosity
Creators: name: Smith, M.
name: Sullivan, M.
name: Wiseman, P.
name: Kessler, R.
name: Scolnic, D.
name: Brout, D.
name: D'Andrea, C. B.
name: Davis, T. M.
name: Foley, R. J.
name: Frohmaier, C.
name: Galbany, L.
name: Gupta, R. R.
name: Gutiérrez, C. P.
name: Hinton, S. R.
name: Kelsey, L.
name: Lidman, C.
name: Macaulay, E.
name: Möller, A.
name: Nichol, R. C.
name: Nugent, P.
name: Palmese, A.
name: Pursiainen, M.
name: Sako, M.
name: Thomas, R. C.
name: Tucker, B. E.
name: Carollo, D.
name: Lewis, G. F.
name: Sommer, N. E.
name: Abbott, T. M. C.
name: Aguena, M.
name: Allam, S.
name: Avila, S.
name: Bertin, E.
name: Bhargava, S.
name: Brooks, D.
name: Buckley-Geer, E.
name: Burke, D. L.
name: Rosell, A. Carnero
name: Kind, M. Carrasco
name: Costanzi, M.
name: da Costa, L. N.
name: De Vicente, J.
name: Desai, S.
name: Diehl, H. T.
name: Doel, P.
name: Eifler, T. F.
name: Everett, S.
name: Flaugher, B.
name: Fosalba, P.
name: Frieman, J.
name: García-Bellido, J.
name: Gaztanaga, E.
name: Glazebrook, K.
name: Gruen, D.
name: Gruendl, R. A.
name: Gschwend, J.
name: Gutierrez, G.
name: Hartley, W. G.
name: Hollowood, D. L.
name: Honscheid, K.
name: James, D. J.
name: Krause, E.
name: Kuehn, K.
name: Kuropatkin, N.
name: Lima, M.
name: MacCrann, N.
name: Maia, M. A. G.
name: Marshall, J. L.
name: Martini, P.
name: Melchior, P.
name: Menanteau, F.
name: Miquel, R.
name: Paz-Chinchón, F.
name: Plazas, A. A.
name: Romer, A. K.
name: Roodman, A.
name: Rykoff, E. S.
name: Sanchez, E.
name: Scarpine, V.
name: Schubnell, M.
name: Serrano, S.
name: Sevilla-Noarbe, I.
name: Suchyta, E.
name: Swanson, M. E. C.
name: Tarle, G.
name: Thomas, D.
name: Tucker, D. L.
name: Varga, T. N.
name: Walker, A. R.
name: :
name: Collaboration, The Dark Energy Survey
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: We present improved photometric measurements for the host galaxies of 206 spectroscopically confirmed type Ia supernovae discovered by the Dark Energy Survey Supernova Program (DES-SN) and used in the first DES-SN cosmological analysis. Fitting spectral energy distributions to the $griz$ photometric measurements of the DES-SN host galaxies, we derive stellar masses and star-formation rates. For the DES-SN sample, when considering a 5D ($z$, $x_1$, $c$, $α$, $β$) bias correction, we find evidence of a Hubble residual `mass step', where SNe Ia in high mass galaxies ($&gt;10^{10} \textrm{M}_{\odot}$) are intrinsically more luminous (after correction) than their low mass counterparts by $γ=0.040\pm0.019$mag. This value is larger by $0.031$mag than the value found in the first DES-SN cosmological analysis. This difference is due to a combination of updated photometric measurements and improved star formation histories and is not from host-galaxy misidentification. When using a 1D (redshift-only) bias correction the inferred mass step is larger, with $γ=0.066\pm0.020$mag. The 1D-5D $γ$ difference for DES-SN is $0.026\pm0.009$mag. We show that this difference is due to a strong correlation between host galaxy stellar mass and the $x_1$ component of the 5D distance-bias correction. To better understand this effect, we include an intrinsic correlation between light-curve width and stellar mass in simulated SN Ia samples. We show that a 5D fit recovers $γ$ with $-9$mmag bias compared to a $+2$mmag bias for a 1D fit. This difference can explain part of the discrepancy seen in the data. Improvements in modeling correlations between galaxy properties and SN is necessary to determine the implications for $γ$ and ensure unbiased precision estimates of the dark energy equation-of-state as we enter the era of LSST.
description: 27 pages, 13 figures; Submitted to MNRAS