Optical polarization from colliding stellar stream shocks in a tidal disruption event

• 成果类型: Article
• 署名作者: Liodakis, I.; Koljonen, K. I. I.; Blinov, D.; Lindfors, E.; Alexander, K. D.; Hovatta, T.; Berton, M.; Hajela, A.; Jormanainen, J.; Kouroumpatzakis, K.; Mandarakas, N.; Nilsson, K.
• 署名单位: University of Turku; Aalto University; Norwegian University of Science & Technology (NTNU); Foundation for Research & Technology - Hellas (FORTH); University of Crete; Northwestern University; University of Arizona; European Southern Observatory; University of Copenhagen; Niels Bohr Institute; University of Turku; Czech Academy of Sciences; Astronomical Institute of the Czech Academy of Sciences
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-12742
• DOI: 10.1126/science.abj9570
• 发表日期: 2023-05-11
• 页码: 656-658
• 关键词: disk formation; polarimetry; afterglow; candidate; POWERS; nearby; masses; light

摘要

A tidal disruption event (TDE) occurs when a supermassive black hole rips apart a passing star. Part of the stellar material falls toward the black hole, forming an accretion disk that in some cases launches a relativistic jet. We performed optical polarimetry observations of a TDE, AT 2020mot. We find a peak linear polarization degree of 25 +/- 4%, consistent with highly polarized synchrotron radiation, as is typically observed from relativistic jets. However, our radio observations, taken up to 8 months after the optical peak, do not detect the corresponding radio emission expected from a relativistic jet. We suggest that the linearly polarized optical emission instead arises from shocks that occur during accretion disk formation, as the stream of stellar material collides with itself.