The Dark Energy Survey Supernova Program results: Type Ia Supernova brightness correlates with host galaxy dust

This is an electronic version of an article published in Monthly Notices of the Royal Astronomical Society. C. Meldorf et al. in “The Dark Energy Survey Supernova Program results: Type Ia Supernova brightness correlates with host galaxy dust”. Monthly Notices of the Royal Astronomical Society 518.2 (2023): 1985-2004Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, los autores pertenecientes a la UAM y el nombre del grupo de colaboración, si lo hubiereCosmological analyses with type Ia supernovae (SNe Ia) often assume a single empirical relation between color and luminosity (β) and do not account for varying host-galaxy dust properties. However, from studies of dust in large samples of galaxies, it is known that dust attenuation can vary significantly. Here we take advantage of state-of-the-art modeling of galaxy properties to characterize dust parameters (dust attenuation AV , and a parameter describing the dust law slope RV ) for the Dark Energy Survey (DES) SN Ia host galaxies using the publicly available BAGPIPES code. Utilizing optical and infrared data of the hosts alone, we find three key aspects of host dust that impact SN Ia cosmology: 1) there exists a large range (∼ 1 − 6) of host RV 2) high stellar mass hosts have RV on average ∼ 0.7 lower than that of low-mass hosts 3) there is a significant (> 3σ) correlation between the Hubble diagram residuals of red SNe Ia that when corrected for reduces scatter by ∼ 13% and the significance of the “mass step” to ∼ 1σ. These represent independent confirmations of recent predictions based on dust that attempted to explain the puzzling “mass step” and intrinsic scatter (σint) in SN Ia analyses. We also find that red-sequence galaxies have both lower and more peaked dust law slope distributions on average in comparison to non red-sequence galaxies. We find that the SN Ia β and σint both differ by > 3σ when determined separately for red-sequence galaxy and all other galaxy hosts. The agreement between fitted host-RV and SN Ia β & σint suggests that host dust properties play a major role in SN Ia color-luminosity standardization and supports the claim that SN Ia intrinsic scatter is driven by RV variatio

The Dark Energy Survey Supernova Program results: Type Ia Supernova brightness correlates with host galaxy dust

Cosmological analyses with type Ia supernovae (SNe Ia) often assume a single empirical relation between color and luminosity ($\beta$) and do not account for varying host-galaxy dust properties. However, from studies of dust in large samples of galaxies, it is known that dust attenuation can vary significantly. Here we take advantage of state-of-the-art modeling of galaxy properties to characterize dust parameters (dust attenuation $A_V$, and a parameter describing the dust law slope $R_V$) for the Dark Energy Survey (DES) SN Ia host galaxies using the publicly available \texttt{BAGPIPES} code. Utilizing optical and infrared data of the hosts alone, we find three key aspects of host dust that impact SN Ia cosmology: 1) there exists a large range ($\sim1-6$) of host $R_V$ 2) high stellar mass hosts have $R_V$ on average $\sim0.7$ lower than that of low-mass hosts 3) there is a significant ($>3\sigma$) correlation between the Hubble diagram residuals of red SNe Ia that when corrected for reduces scatter by $\sim13\%$ and the significance of the ``mass step'' to $\sim1\sigma$. These represent independent confirmations of recent predictions based on dust that attempted to explain the puzzling ``mass step'' and intrinsic scatter ($\sigma_{\rm int}$) in SN Ia analyses. We also find that red-sequence galaxies have both lower and more peaked dust law slope distributions on average in comparison to non red-sequence galaxies. We find that the SN Ia $\beta$ and $\sigma_{\rm int}$ both differ by $>3\sigma$ when determined separately for red-sequence galaxy and all other galaxy hosts. The agreement between fitted host-$R_V$ and SN Ia $\beta$ \& $\sigma_{\rm int}$ suggests that host dust properties play a major role in SN Ia color-luminosity standardization and supports the claim that SN Ia intrinsic scatter is driven by $R_V$ variation.Comment: 22 pages. Submitted to MNRA

The Dark Energy Survey Supernova Program results: Type Ia Supernova brightness correlates with host galaxy dust

International audienceCosmological analyses with type Ia supernovae (SNe Ia) often assume a single empirical relation between colour and luminosity (β) and do not account for varying host-galaxy dust properties. However, from studies of dust in large samples of galaxies, it is known that dust attenuation can vary significantly. Here we take advantage of state-of-the-art modeling of galaxy properties to characterize dust parameters (dust attenuation AV, and a parameter describing the dust law slope RV) for 1100 Dark Energy Survey (DES) SN host galaxies. Utilizing optical and infrared data of the hosts alone, we find three key aspects of host dust that impact SN cosmology: 1) there exists a large range (~1 - 6) of host RV 2) high stellar mass hosts have RV on average ~0.7 lower than that of low-mass hosts 3) for a subsample of 81 spectroscopically classified SNe there is a significant (>3σ) correlation between the Hubble diagram residuals of red SNe Ia and the host RV that when corrected for reduces scatter by $\sim 13{{\%}}$ and the significance of the 'mass step' to ~1σ. These represent independent confirmations of recent predictions based on dust that attempted to explain the puzzling 'mass step' and intrinsic scatter (σint) in SN Ia analyses