Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 1, 2015 | Published + Submitted + Supplemental Material
Journal Article Open

Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 μm


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 RV = 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.

Additional Information

© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 July 6. Received 2015 June 30; in original form 2015 April 8. First published online September 7, 2015. We would like to thank Denise Taylor at Space Telescope Science Institute for advising and assisting us in carrying out this programme. We would also like to thank Livia Vallini for carrying out observations of SN 2012cg during the Nordic Millimetre and Optical/NIR Astronomy Summer School 2012. We are grateful to the anonymous referee for thoroughly going through the manuscript and providing us with many useful comments. RA and AG acknowledge support from the Swedish Research Council and the Swedish Space Board. PJB and the Swift Optical/Ultraviolet Supernova Archive (SOUSA) are supported by NASA's Astrophysics Data Analysis Program through grant NNX13AF35G. The work of PS is sponsored by FCT – Fundação para a Ciência e Tecnologia, under the grant SFRH/BD/62075/2009. VS acknowledges support from Fundação para a Ciência e a Tecnologia (Ciência 2008) and grant PTDC/CTE-AST/112582/2009. NER acknowledges the support from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 267251 'Astronomy Fellowships in Italy' (AstroFIt). The Oskar Klein Centre is funded by the Swedish Research Council. EYH acknowledge the generous support provided by the Danish Agency for Science and Technology and Innovation through a Sapere Aude Level 2 grant. The Dark Cosmology Centre is funded by the DNRF. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement no. EGGS-278202. Observations were made with the Hubble Space Telescope; the NOT, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. STSDAS and PyRAF is a product of the Space Telescope Science Institute, which is operated by AURA for NASA. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Attached Files

Submitted - 1504.02101v2.pdf

Published - MNRAS-2015-Amanullah-3300-28.pdf

Supplemental Material - suppl_data.zip


Files (14.9 MB)
Name Size Download all
6.8 MB Preview Download
8.0 MB Preview Download
5.9 kB Preview Download

Additional details

August 20, 2023
August 20, 2023