Concerning Colour: The Effect of Environment on Type Ia Supernova Colour in the Dark Energy Survey

Kelsey, L.; Sullivan, M.; Wiseman, P.; Armstrong, P.; Chen, R.; Brout, D.; Davis, T. M.; Dixon, M.; Frohmaier, C.; Galbany, L.; Graur, O.; Kessler, R.; Lidman, C.; Möller, A.; Popovic, B.; Rose, B.; Scolnic, D.; Smith, M.; Vincenzi, M.; Abbott, T. M. C.; Aguena, M.; Allam, S.; Alves, O.; Annis, J.; Bacon, D.; Bertin, E.; Bocquet, S.; Brooks, D.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Costanzi, M.; Da Costa, L. N.; Pereira, M. E. S.; Desai, S.; Diehl, H. T.; Everett, S.; Ferrero, I.; Frieman, J.; García-Bellido, J.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Hinton, S. R.; Hollowood, D. L.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lewis, G. F.; Mena-Fernández, J.; Miquel, R.; Palmese, A.; Paz-Chinchón, F.; Pieres, A.; Plazas Malagón, A. A.; Raveri, M.; Rodriguez-Monroy, M.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Tucker, D. L.; Weaverdyck, N.

doi:10.1093/mnras/stac3711

Recent analyses have found intriguing correlations between the colour (c) of type Ia supernovae (SNe Ia) and the size of their 'mass-step', the relationship between SN Ia host galaxy stellar mass (Mstellar) and SN Ia Hubble residual, and suggest that the cause of this relationship is dust. Using 675 photometrically-classified SNe Ia from the Dark Energy Survey 5-year sample, we study the differences in Hubble residual for a variety of global host galaxy and local environmental properties for SN Ia subsamples split by their colour. We find a 3σ difference in the mass-step when comparing blue (c < 0) and red (c > 0) SNe. We observe the lowest r.m.s. scatter (~0.14 mag) in the Hubble residual for blue SNe in low mass/blue environments, suggesting that this is the most homogeneous sample for cosmological analyses. By fitting for c-dependent relationships between Hubble residuals and Mstellar, approximating existing dust models, we remove the mass-step from the data and find tentative ~2σ residual steps in rest-frame galaxy U - R colour. This indicates that dust modelling based on Mstellar may not fully explain the remaining dispersion in SN Ia luminosity. Instead, accounting for a c-dependent relationship between Hubble residuals and global U - R, results in ≤1σ residual steps in Mstellar and local U - R, suggesting that U - R provides different information about the environment of SNe Ia compared to Mstellar, and motivating the inclusion of galaxy U - R colour in SN Ia distance bias correction....

Concerning Colour: The Effect of Environment on Type Ia Supernova Colour in the Dark Energy Survey / Kelsey, L.; Sullivan, M.; Wiseman, P.; Armstrong, P.; Chen, R.; Brout, D.; Davis, T. M.; Dixon, M.; Frohmaier, C.; Galbany, L.; Graur, O.; Kessler, R.; Lidman, C.; Möller, A.; Popovic, B.; Rose, B.; Scolnic, D.; Smith, M.; Vincenzi, M.; Abbott, T. M. C.; Aguena, M.; Allam, S.; Alves, O.; Annis, J.; Bacon, D.; Bertin, E.; Bocquet, S.; Brooks, D.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Costanzi, M.; da Costa, L. N.; Pereira, M. E. S.; Desai, S.; Diehl, H. T.; Everett, S.; Ferrero, I.; Frieman, J.; García-Bellido, J.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Hinton, S. R.; Hollowood, D. L.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lewis, G. F.; Mena-Fernández, J.; Miquel, R.; Palmese, A.; Paz-Chinchón, F.; Pieres, A.; Plazas Malagón, A. A.; Raveri, M.; Rodriguez-Monroy, M.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Tucker, D. L.; Weaverdyck, N.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 519:2(2023), pp. 3046-3063. [10.1093/mnras/stac3711]