Collapsars as Sites of r-process Nucleosynthesis: Systematic Photometric Near-infrared Follow-up of Type Ic-BL Supernovae
Shreya Anand, Jennifer Barnes, Sheng Yang, M. M. Kasliwal, M. W. Coughlin, J. Sollerman, Kishalay De, C. Fremling, A. Corsi, Anna Y. Q. Ho, Arvind Balasubramanian, Conor M. B. Omand, Gokul P. Srinivasaragavan, S. B. Cenko, Tomás Ahumada, Igor Andreoni, A. Dahiwale, Kaustav K. Das, J. Jencson, Viraj Karambelkar, Harsh Kumar, Brian D. Metzger, D. A. Perley, Nikhil Sarin, T. Schweyer, S. Schulze, Y. Sharma, Tawny Sit, Robert Stein, L. Tartaglia, Samaporn Tinyanont, Anastasios Tzanidakis, Jan van Roestel, Yuhan Yao, J. S. Bloom, D. Cook, Richard Dekany, M. J. Graham, Steven L. Groom, D. L. Kaplan, Frank J. Masci, Michael S. Medford, Reed Riddle, Chaoran Zhang
Abstract
Abstract One of the open questions following the discovery of GW170817 is whether neutron star (NS) mergers are the only astrophysical sites capable of producing r -process elements. Simulations have shown that 0.01–0.1 M ⊙ of r -process material could be generated in the outflows originating from the accretion disk surrounding the rapidly rotating black hole that forms as a remnant to both NS mergers and collapsing massive stars associated with long-duration gamma-ray bursts (collapsars). The hallmark signature of r -process nucleosynthesis in the binary NS merger GW170817 was its long-lasting near-infrared (NIR) emission, thus motivating a systematic photometric study of the light curves of broad-lined stripped-envelope (Ic-BL) supernovae (SNe) associated with collapsars. We present the first systematic study of 25 SNe Ic-BL—including 18 observed with the Zwicky Transient Facility and 7 from the literature—in the optical/NIR bands to determine what quantity of r -process material, if any, is synthesized in these explosions. Using semi-analytic models designed to account for r -process production in SNe Ic-BL, we perform light curve fitting to derive constraints on the r -process mass for these SNe. We also perform independent light curve fits to models without the r -process. We find that the r -process-free models are a better fit to the light curves of the objects in our sample. Thus, we find no compelling evidence of r -process enrichment in any of our objects. Further high-cadence infrared photometric studies and nebular spectroscopic analysis would be sensitive to smaller quantities of r -process ejecta mass or indicate whether all collapsars are completely devoid of r -process nucleosynthesis.