Herschel limits on far-infrared emission from circumstellar dust around nearby Type Ia supernovae

TL;DR

This study used Herschel Space Observatory data to set upper limits on circumstellar dust emission around three nearby Type Ia supernovae, constraining the amount of pre-existing dust in their environments.

Contribution

First constraints on circumstellar dust around nearby Type Ia supernovae using far-infrared observations from Herschel.

Findings

SN 2011fe has a dust mass upper limit of 7 x 10^-3 M_sun.

No far-infrared detection was made for the three supernovae.

Constraints are less stringent for SNe 2011by and 2012cg.

Abstract

We report upper limits on dust emission at far-infrared (IR) wavelengths from three nearby Type Ia supernovae: SNe 2011by, 2011fe and 2012cg. Observations were carried out at 70 um and 160 um with the Photodetector Array Camera and Spectrometer (PACS) on board the Herschel Space Observatory. None of the supernovae were detected in the far-IR, allowing us to place upper limits on the amount of pre-existing dust in the circumstellar environment. Due to its proximity, SN 2011fe provides the tightest constraints, M_dust < 7 * 10^-3 M_sun at a 3 sigma-level for dust temperatures T_dust ~500 K assuming silicate or graphite dust grains of size a = 0.1 um. For SNe 2011by and 2012cg the corresponding upper limits are less stringent, with M_dust < 0.1 M_sun for the same assumptions.