A Systematic Study of Ia-CSM Supernovae from the ZTF Bright Transient Survey

May 2023 • 2023ApJ...948...52S

Authors • Sharma, Yashvi • Sollerman, Jesper • Fremling, Christoffer • Kulkarni, Shrinivas R. • De, Kishalay • Irani, Ido • Schulze, Steve • Strotjohann, Nora Linn • Gal-Yam, Avishay • Maguire, Kate • Perley, Daniel A. • Bellm, Eric C. • Kool, Erik C. • Brink, Thomas G. • Bruch, Rachel • Deckers, Maxime • Dekany, Richard • Dugas, Alison • Filippenko, Alexei V. • Goldwasser, Samantha • Graham, Matthew J. • Graham, Melissa L. • Groom, Steven L. • Hankins, Matt • Jencson, Jacob • Johansson, Joel P. • Karambelkar, Viraj • Kasliwal, Mansi M. • Masci, Frank J. • Medford, Michael S. • Neill, James D. • Nir, Guy • Riddle, Reed L. • Rigault, Mickael • Schweyer, Tassilo • Terwel, Jacco H. • Yan, Lin • Yang, Yi • Yao, Yuhan

Abstract • Among the supernovae (SNe) that show strong interaction with a circumstellar medium (CSM), there is a rare subclass of Type Ia supernovae, SNe Ia-CSM, which show strong narrow hydrogen emission lines much like SNe IIn but on top of a diluted Type Ia spectrum. The only previous systematic study of this class identified 16 SNe Ia-CSM, eight historic and eight from the Palomar Transient Factory (PTF). Now using the successor survey to PTF, the Zwicky Transient Facility (ZTF), we have classified 12 additional SNe Ia-CSM through the systematic Bright Transient Survey (BTS). Consistent with previous studies, we find these SNe to have slowly evolving optical light curves with peak absolute magnitudes between -19.1 and -21, spectra having weak Hβ and large Balmer decrements of ~7. Out of the 10 SNe from our sample observed by NEOWISE, nine have 3σ detections, with some SNe showing a reduction in the red wing of Hα, indicative of newly formed dust. We do not find our SN Ia-CSM sample to have a significantly different distribution of equivalent widths of He I λ5876 than SNe IIn as observed in Silverman et al. The hosts tend to be late-type galaxies with recent star formation. We derive a rate estimate of ${29}_{-21}^{+27}$ Gpc-3 yr-1 for SNe Ia-CSM, which is ~0.02%-0.2% of the SN Ia rate. We also identify six ambiguous SNe IIn/Ia-CSM in the BTS sample and including them gives an upper limit rate of 0.07%-0.8%. This work nearly doubles the sample of well-studied Ia-CSM objects in Silverman et al., increasing the total number to 28.


IPAC Authors

Jacob Jencson

Assistant Scientist

Frank Masci

Senior Scientist