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Carnegie Supernova Project-II: Near-infrared Spectroscopic Diversity of Type II Supernovae

Davis, S. and Hsiao, E. Y. and Ashall, C. and Hoeflich, P. and Phillips, M. M. and Marion, G. H. and Kirshner, R. P. and Morrell, N. and Sand, D. J. and Burns, C. and Contreras, C. and Stritzinger, M. and Anderson, J. P. and Baron, E. and Diamond, T. and Gutierrez, C. P. and Hamuy, M. and Holmbo, S. and Kasliwal, M. M. and Krisciunas, K. and Kumar, S. and Lu, J. and Pessi, P. J. and Piro, A. L. and Prieto, J. L. and Shahbandeh, M. and Suntzeff, N. B. (2019) Carnegie Supernova Project-II: Near-infrared Spectroscopic Diversity of Type II Supernovae. Astrophysical Journal, 887 (1). Art. No. 4. ISSN 1538-4357. doi:10.3847/1538-4357/ab4c40.

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We present 81 near-infrared (NIR) spectra of 30 Type II supernovae (SNe II) from the Carnegie Supernova Project-II (CSP-II), the largest such data set published to date. We identify a number of NIR features and characterize their evolution over time. The NIR spectroscopic properties of SNe II fall into two distinct groups. This classification is first based on the strength of the He i λ1.083 μm absorption during the plateau phase; SNe II are either significantly above (spectroscopically strong) or below 50 Å (spectroscopically weak) in pseudo equivalent width. However, between the two groups other properties, such as the timing of CO formation and the presence of Sr ii, are also observed. Most surprisingly, the distinct weak and strong NIR spectroscopic classes correspond to SNe II with slow and fast declining light curves, respectively. These two photometric groups match the modern nomenclature of SNe IIP, which show a long duration plateau, and IIL, which have a linear declining light curve. Including NIR spectra previously published, 18 out of 19 SNe II follow this slow declining-spectroscopically weak and fast declining-spectroscopically strong correspondence. This is in apparent contradiction to the recent findings in the optical that slow and fast decliners show a continuous distribution of properties. The weak SNe II show a high-velocity component of helium that may be caused by a thermal excitation from a reverse shock created by the outer ejecta interacting with the red supergiant wind, but the origin of the observed dichotomy is not understood. Further studies are crucial in determining whether the apparent differences in the NIR are due to distinct physical processes or a gap in the current data set.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hsiao, E. Y.0000-0003-1039-2928
Phillips, M. M.0000-0003-2734-0796
Kasliwal, M. M.0000-0002-5619-4938
Piro, A. L.0000-0001-6806-0673
Prieto, J. L.0000-0003-1072-2712
Additional Information:© 2019 The American Astronomical Society. Received 2019 July 25; revised 2019 October 4; accepted 2019 October 7; published 2019 December 4. The authors would like to thank the anonymous referee for their comments. The work of the CSP-II has been generously supported by the National Science Foundation (NSF) under grants AST-1008343, AST-1613426, AST-1613455, and AST-1613472. The CSP-II was also supported in part by the Danish Agency for Science and Technology and Innovation through a Sapere Aude Level 2 grant. We would like to thank Michael Cushing for his work on Spextool in processing low-resolution data. P.H. acknowledges support by the NSF grant 1715133. Research by D.J.S. is supported by NSF grants AST-1821987, AST-1821967, AST-1813708, and AST-1813466. CPG acknowledges support from EU/FP7-ERC grant no. [615929]. Support for J.L.P. is provided in part by FONDECYT through the grant 1191038 and by the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS. Software: firehose (Simcoe et al. 2013), xtellcor (Vacca et al. 2003), Spextool (Cushing et al. 2004), SNID (Blondin & Tonry 2007).
Group:Astronomy Department
Funding AgencyGrant Number
Danish Agency for Science and Technology and InnovationUNSPECIFIED
European Research Council (ERC)615929
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1191038
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
Subject Keywords:Core-collapse supernovae; Near infrared astronomy; Spectroscopy
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Core-collapse supernovae (304); Near infrared astronomy (1093); Spectroscopy (1558)
Record Number:CaltechAUTHORS:20191121-111931871
Persistent URL:
Official Citation:S. Davis et al 2019 ApJ 887 4
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99987
Deposited By: Tony Diaz
Deposited On:21 Nov 2019 19:29
Last Modified:16 Nov 2021 17:50

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