分类： 天文学 >> 天文学 提交时间： 2023-02-19
Shreya Anand
Jennifer Barnes
Sheng Yang
Mansi M. Kasliwal
Michael W. Coughlin
Jesper Sollerman
Kishalay De
Christoffer Fremling
Alessandra Corsi
Anna Y. Q. Ho
Arvind Balasubramanian
Conor Omand
Gokul P. Srinivasaragavan
S. Bradley Cenko
Tomas Ahumada
Igor Andreoni
Aishwarya Dahiwale
Kaustav Kashyap Das
Jacob Jencson
Viraj Karambelkar
摘要： One of the open questions following the discovery of GW170817 is whether neutron star mergers are the only astrophysical sites capable of producing r-process elements. Simulations have shown that 0.01-0.1M$_\odot$ 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 neutron star mergers and collapsing massive stars associated with long-duration gamma-ray bursts (collapsars). The hallmark signature of r-process nucleosynthesis in the binary neutron star merger GW170817 was its long-lasting near-infrared emission, thus motivating a systematic photometric study of the light curves of broadlined stripped-envelope (Ic-BL) supernovae (SNe) associated with collapsars. We present the first systematic study of 25 SNe Ic-BL -- discovered with the Zwicky Transient Facility and from the literature -- in the optical/near-infrared 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 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 conclude that there is 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.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Erik C. Kool
Joel Johansson
Jesper Sollerman
Javier Moldón
Takashi J. Moriya
Steve Schulze
Laura Chomiuk
Chelsea Harris
Miguel Pérez-Torres
Seppo Mattila
Peter Lundqvist
Matthew Graham
Sheng Yang
Daniel A. Perley
Nora Linn Strotjohann
Christoffer Fremling
Avishay Gal-Yam
Jeremy Lezmy
Kate Maguire
Conor Omand
摘要： Type Ia supernovae are thought to be carbon-oxygen white dwarf stars that explode after accreting material from a companion star, but despite extensive studies the nature of the companion star is still poorly understood, as is the explosion mechanism. In the single degenerate scenario, the companion is a non-degenerate star that loses material through winds and/or binary interaction, and a few Type Ia supernovae have shown evidence for hydrogen-rich circumstellar material. We present here the study of SN 2020eyj, a unique Type Ia supernova showing delayed interaction with helium-rich, but hydrogen-poor, circumstellar material. This material surrounding SN 2020eyj is revealed by its unusual light curve and infrared emission, narrow helium emission lines and, for the first time ever in a Type Ia supernova, also a radio counterpart. The circumstellar material likely originates from the companion star, providing the first direct evidence for a, so far hypothesized, single degenerate progenitor system composed of a white dwarf and a helium donor star.
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