First Cosmology Results using Type Ia Supernovae from the Dark Energy Survey: The Effect of Host Galaxy Properties on Supernova Luminosity

Smith, M

Sullivan, M

Wiseman, P

Kessler, R

Scolnic, D

Brout, D

D'Andrea, CB

Davis, TM

Foley, RJ

Frohmaier, C

Galbany, L

Gupta, RR

Gutiérrez, CP

Hinton, SR

Kelsey, L

Lidman, C

Macaulay, E

Möller, A

Nichol, RC

Nugent, P

Palmese, A

Pursiainen, M

Sako, M

Swann, E

Thomas, RC

Tucker, BE

Vincenzi, M

Carollo, D

Lewis, GF

Sommer, NE

Abbott, TMC

Aguena, M

Allam, S

Avila, S

Bertin, E

Bhargava, S

Brooks, D

Buckley-Geer, E

Burke, DL

Rosell, AC

Kind, MC

Costanzi, M

da Costa, LN

de Vicente, J

Desai, S

Diehl, HT

Doel, P

Eifler, TF

Everett, S

Flaugher, B

Fosalba, P

Frieman, J

García-Bellido, J

Gaztanaga, E

Glazebrook, K

Gruen, D

Gruendl, RA

Gschwend, J

Gutierrez, G

Hartley, WG

Hollowood, DL

Honscheid, K

James, DJ

Krause, E

Kuehn, K

Kuropatkin, N

Lima, M

MacCrann, N

Maia, MAG

Marshall, JL

Martini, P

Melchior, P

Menanteau, F

Miquel, R

Paz-Chinchón, F

Plazas, AA

Romer, AK

Roodman, A

Rykoff, ES

Sanchez, E

Scarpine, V

Schubnell, M

Serrano, S

Sevilla-Noarbe, I

Suchyta, E

Swanson, MEC

Tarle, G

Thomas, D

Tucker, DL

Varga, TN

Walker, AR

2020-04-23T20:37:57Z

2020-04-23T20:37:57Z

2020-04-23T20:37:55Z

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 ($z$, $x_1$, $c$, $\alpha$, $\beta$) bias correction, we find evidence of a Hubble residual `mass step', where SNe Ia in high mass galaxies ($>10^{10} \textrm{M}_{\odot}$) are intrinsically more luminous (after correction) than their low mass counterparts by $\gamma=0.040\pm0.019$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 $\gamma=0.066\pm0.020$mag. The 1D-5D $\gamma$ 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 $\gamma$ 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 $\gamma$ and ensure unbiased precision estimates of the dark energy equation-of-state as we enter the era of LSST.

https://hdl.handle.net/10161/20491

Oxford University Press (OUP)

astro-ph.CO

astro-ph.CO

astro-ph.GA

First Cosmology Results using Type Ia Supernovae from the Dark Energy Survey: The Effect of Host Galaxy Properties on Supernova Luminosity

Journal article

Scolnic, D|0000-0002-4934-5849

Trinity College of Arts & Sciences

Physics

Duke