Near-infrared and Optical Nebular-phase Spectra of Type Ia Supernovae SN 2013aa and SN 2017cbv in NGC 5643

Creators: Kumar, Sahana; Hsiao, Eric Y.; Ashall, C.; Phillips, M. M.; Morrell, N.; Hoeflich, P.; Burns, C. R.; Galbany, L.; Baron, E.; Contreras, C.; Davis, S.; Diamond, T.; Förster, F.; Graham, M. L.; Karamehmetoglu, E.; Kirshner, R. P.; Koribalski, B.; Krisciunas, K.; Lu, J.; Marion, G. H.; Pessi, P. J.; Piro, A. L.; Shahbandeh, M.; Stritzinger, M. D.; Suntzeff, N. B.; Uddin, S. A.

Abstract

We present multiwavelength time-series spectroscopy of SN 2013aa and SN 2017cbv, two Type Ia supernovae (SNe Ia) on the outskirts of the same host galaxy, NGC 5643. This work utilizes new nebular-phase near-infrared (NIR) spectra obtained by the Carnegie Supernova Project-II, in addition to previously published optical and NIR spectra. Using nebular-phase [Fe ii] lines in the optical and NIR, we examine the explosion kinematics and test the efficacy of several common emission-line-fitting techniques. The NIR [Fe ii] 1.644 μm line provides the most robust velocity measurements against variations due to the choice of the fit method and line blending. The resulting effects on velocity measurements due to choosing different fit methods, initial fit parameters, continuum and line profile functions, and fit region boundaries were also investigated. The NIR [Fe ii] velocities yield the same radial shift direction as velocities measured using the optical [Fe ii] λ7155 line, but the sizes of the shifts are consistently and substantially lower, pointing to a potential issue in optical studies. The NIR [Fe ii] 1.644 μm emission profile shows a lack of significant asymmetry in both SNe, and the observed low velocities elevate the importance for correcting for any velocity contribution from the host galaxy's rotation. The low [Fe ii] velocities measured in the NIR at nebular phases disfavor progenitor scenarios in close double-degenerate systems for both SN 2013aa and SN 2017cbv. The time evolution of the NIR [Fe ii] 1.644 μm line also indicates moderately high progenitor white dwarf central density and potentially high magnetic fields.

Additional Information

© 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. We thank the Las Campanas technical staff for their continued support over the years. The CSP-II has been supported by NSF grants AST-1008343, AST-1613426, AST-1613455, and AST-1613472, as well as the Danish Agency for Science and Technology and Innovation through a Sapere Aude Level 2 grant. This research has made use of the services of the ESO Science Archive Facility, based on observations collected at the European Southern Observatory under ESO program 095.B-0532. The Australia Telescope Compact Array is part of the Australia Telescope National Facility, which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. S.K. was supported by the Florida Space Consortium Research Grant. L.G. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033, and the European Social Fund (ESF) "Investing in your future" under the 2019 Ramón y Cajal program RYC2019-027683-I and the PID2020-115253GA-I00 HOSTFLOWS project, from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016, and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M. E.B. was supported in part by NASA grant 80NSSC20K0538. P.H. is supported by the NSF grant AST-1715133. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. Facilities: Magellan:Baade (FIRE) - , Gemini South (GMOS) - , VLT (XShooter) - , ATCA (375 m and 1.5 A arrays) - , Magellan:Clay (LDSS-3). - Software: astropy (Collaboration et al. 2013; Astropy Collaboration et al. 2018), LMFIT (Newville et al. 2014).

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