Nebular spectroscopy of SN 2014J: Detection of stable nickel in near-infrared spectra

¹ Oskar Klein Centre, Department of Physics, Stockholm University, 106 91 Stockholm, Sweden
e-mail: suhail.dhawan@fysik.su.se
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
³ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching bei München, Germany
⁴ Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching bei München, Germany
⁵ Excellence Cluster Universe, Technische Universität München, Boltzmannstraße 2, 85748 Garching, Germany
⁶ Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UK
⁷ Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto ON M5S 3H4, Canada

Received: 20 April 2018
Accepted: 24 July 2018

Abstract

We present near-infrared (NIR) spectroscopy of the nearby supernova 2014J obtained ∼450 d after explosion. We detect the [Ni II] 1.939 μm line in the spectra indicating the presence of stable ⁵⁸Ni in the ejecta. The stable nickel is not centrally concentrated but rather distributed as the iron. The spectra are dominated by forbidden [Fe II] and [Co II] lines. We used lines, in the NIR spectra, arising from the same upper energy levels to place constraints on the extinction from host galaxy dust. We find that that our data are in agreement with the high A_V and low R_V found in earlier studies from data near maximum light. Using a ⁵⁶Ni mass prior from near maximum light γ-ray observations, we find 0.053 ± 0.018 M_⊙ of stable nickel to be present in the ejecta. We find that the iron group features are redshifted from the host galaxy rest frame by ∼600 km s⁻¹.