Swift Ultraviolet Observations of Supernova 2014J in M82: Large Extinction from Interstellar Dust

Abstract

We present optical and ultraviolet (UV) photometry and spectra of the very nearby and highly reddened supernova (SN) 2014J in M82 obtained with the Swift Ultra-Violet/Optical Telescope (UVOT). Comparison of the UVOT grism spectra of SN~2014J with Hubble Space Telescope observations of SN2011fe or UVOT grism spectra of SN~2012fr are consistent with an extinction law with a low value of R_V~1.4. The high reddening causes the detected photon distribution in the broadband UV filters to have a much longer effective wavelength than for an unreddened SN. The light curve evolution is consistent with this shift and does not show a flattening due to photons being scattered back into the line of sight. The light curve shapes and color evolution are inconsistent with a contribution scattered into the line of sight by circumstellar dust. We conclude that most or all of the high reddening must come from interstellar dust. We show that even for a single dust composition, there is not a unique reddening law caused by circumstellar scattering. Rather, when considering scattering from a time-variable source, we confirm earlier studies that the reddening law is a function of the dust geometry, column density, and epoch. We also show how an assumed geometry of dust as a foreground sheet in mixed stellar/dust systems will lead to a higher inferred R_V. Rather than assuming the dust around SNe is peculiar, SNe may be useful probes of the interstellar reddening laws in other galaxies.

14 pages including 8 figures

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Cited by in corpus (11)

• Interpreting Flux from Broadband Photometry
• Physical Dust Models for the Extinction toward Supernova 2014J in M82
• Interstellar-Medium Mapping in M82 Through Light Echoes Around Supernova 2014J
• Estimating dust distances to Type Ia supernovae from colour excess time-evolution
• The Extinction Properties of and Distance to the Highly Reddened Type Ia Supernova SN 2012cu
• Properties of interstellar dust responsible for extinction laws with unusually low total-to-selective extinction ratios of Rv=1-2
• Exploration of Aspherical Ejecta Properties in Type Ia Supernova: Progenitor Dependence and Applications to Progenitor Classification
• Optical photometry and spectroscopy of the low-luminosity, broad-lined Ic supernova iPTF15dld
• Dust Extinction towards the Type Ia Supernova 2012cu in NGC 4772
• On the Time Variation of Dust Extinction and Gas Absorption for Type~Ia Supernovae Observed Through Non-uniform Interstellar Medium
• Extract cleaned Swift/UVOT UV grism spectra with uvotpy package