Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 μm
Apr 8, 201529 pages
Published in:
- Mon.Not.Roy.Astron.Soc. 453 (2015) 3, 3300-3328
- Published: Nov 1, 2015
e-Print:
- 1504.02101 [astro-ph.HE]
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Abstract: (Oxford University Press)
We present ultraviolet (UV) observations of six nearby Type Ia supernovae (SNe Ia) obtained with the Hubble Space Telescope, three of which were also observed in the near-IR (NIR) with Wide-Field Camera 3. UV observations with the Swift satellite, as well as ground-based optical and NIR data provide complementary information. The combined data set covers the wavelength range 0.2–2 μm. By also including archival data of SN 2014J, we analyse a sample spanning observed colour excesses up to E(B − V) = 1.4 mag. We study the wavelength-dependent extinction of each individual SN and find a diversity of reddening laws when characterized by the total-to-selective extinction R_V. In particular, we note that for the two SNe with E(B − V) ≳ 1 mag, for which the colour excess is dominated by dust extinction, we find R_V = 1.4 ± 0.1 and R_V = 2.8 ± 0.1. Adding UV photometry reduces the uncertainty of fitted R_V by ∼50 per cent allowing us to also measure R_V of individual low-extinction objects which point to a similar diversity, currently not accounted for in the analyses when SNe Ia are used for studying the expansion history of the Universe.Note:
- 31 pages, 28 figures, accepted for publication in MNRAS
- circumstellar matter
- supernovae: general
- supernovae: individual: SNe 2012cg
- supernovae: individual: 2012cu
- dust, extinction
References(208)
Figures(25)