Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium


Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia show evidence of strong interaction with their circumstellar medium (CSM), and in particular, a hydrogen-rich CSM; we refer to them as SNe Ia-CSM. In the first systematic search for such systems, we have identified 16 SNe Ia-CSM, and here we present new spectra of 13 of them. Six SNe Ia-CSM have been well-studied previously, three were previously known but are analyzed in-depth for the first time here, and seven are new discoveries from the Palomar Transient Factory. The spectra of all SNe Ia-CSM are dominated by Hα emission (with widths of ∼2000 km s−1) and exhibit large Hα/Hβ intensity ratios (perhaps due to collisional excitation of hydrogen via the SN ejecta overtaking slower-moving CSM shells); moreover, they have an almost complete lack of He I emission. They also show possible evidence of dust formation through a decrease in the red wing of Hα 75–100 d past maximum brightness, and nearly all SNe Ia-CSM exhibit strong Na I D absorption from the host galaxy. The absolute magnitudes (uncorrected for host-galaxy extinction) of SNe Ia-CSM are found to be −21.3 ≤ MR ≤ −19 mag, and they also seem to show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM are all late-type spirals similar to the Milky Way, or dwarf irregulars like the Large Magellanic Cloud, which implies that these objects come from a relatively young stellar population. This work represents the most detailed analysis of the SN Ia-CSM class to date. Subject headings: supernovae: general — supernovae: individual (SN 1997cy, SN 1999E, SN 2002ic, SN 2005gj, SN 2008J, SN 2008cg, SN 2011jb, CSS120327:110520–015205, PTF11kx, PTF10htz, PTF10iuf, PTF10yni, PTF11dsb, PTF11hzx, PTF12efc, PTF12hnr) — stars: circumstellar matter 1 Department of Astronomy, University of Texas, Austin, TX 78712-0259, USA. 2 Department of Astronomy, University of California, Berkeley, CA 94720-3411, USA. 3 email: jsilverman@astro.as.utexas.edu. 4 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. 5 Benoziyo Center for Astrophysics, The Weizmann Institute of Science, Rehovot 76100, Israel. 6 School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK. 7 Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117, USA. 8 Department of Physics, University of California, Santa Barbara, CA 93106, USA. 9 Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA. 10 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA. 11 Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA. 12 Clay Fellow. 13 Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA. 14 Observatories of the Carnegie Institution of Science, Pasadena, CA 91101, USA. 15 Department of Astronomy, San Diego State University, San Diego, CA 92182-1221, USA. 16 Deceased 12 December 2011. 17 National Optical Astronomy Observatory, Tucson, AZ 857194933, USA. 18 New York University, Center for Cosmology and Particle

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@inproceedings{Silverman2013TypeIS, title={Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium}, author={Jeffrey M. Silverman and Peter Nugent and Avishay Gal-Yam and M. K. Sullivan and D. Andrew Howell and Alexei V . Filippenko and Iair Arcavi and Sagi Ben-Ami and Joshua S. Bloom and S. Bradley Cenko and Yi Cao and Ryan Chornock and Kelsey I. Clubb and Alison L. Coil and Ryan J. Foley and Melissa L. Graham and Christopher V. Griffith and Assaf Horesh and Mansi Kasliwal and Shrinivas R. Kulkarni and D. C. Leonard and Weidong Li and Thomas Matheson and Adam A. Miller and Maryam Modjaz and Eran Ofek and Yen-Chen Pan and Daniel A. Perley and Dovi Poznanski and Robert M. Quimby and Thea N. Steele and Assaf Sternberg and Dong Xu and Ofer Yaron}, year={2013} }