Physical Dust Models for the Extinction toward Supernova 2014J in M82

TL;DR

This study models the dust extinction toward supernova SN 2014J in M82 using dust models, revealing a steep ultraviolet extinction law, small dust grains, and specific extinction parameters, enhancing understanding of dust effects on supernova observations.

Contribution

The paper introduces detailed dust extinction models for SN 2014J, providing new insights into dust grain size distributions and extinction laws in a starburst galaxy environment.

Findings

Extinction law rises steeply toward ultraviolet wavelengths.

Dust grain sizes are smaller than those in the Milky Way and SMC.

Derived extinction parameters: A_V ≈ 1.9 mag, R_V ≈ 1.7.

Abstract

Type Ia supernovae (SNe Ia) are powerful cosmological "standardizable candles" and the most precise distance indicators. However, a limiting factor in their use for precision cosmology rests on our ability to correct for the dust extinction toward them. SN 2014J in the starburst galaxy M82, the closest detected SN~Ia in three decades, provides unparalleled opportunities to study the dust extinction toward an SN Ia. In order to derive the extinction as a function of wavelength, we model the color excesses toward SN 2014J, which are observationally derived over a wide wavelength range in terms of dust models consisting of a mixture of silicate and graphite. The resulting extinction laws steeply rise toward the far ultraviolet, even steeper than that of the Small Magellanic Cloud (SMC). We infer a visual extinction of $A_V \approx 1.9~\rm mag$, a reddening of $E(B-V)\approx1.1~ \rm mag$, and a total-to-selective extinction ratio of $R_V \approx 1.7$, consistent with that previously derived from photometric, spectroscopic, and polarimetric observations. The size distributions of the dust in the interstellar medium toward SN 2014J are skewed toward substantially smaller grains than that of the Milky Way and the SMC.