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

Costanzi, M.;
2023-01-01

Abstract

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....
2023
2022
Pubblicato
https://academic.oup.com/mnras/article/519/2/3046/6939845
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/3037675
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