A1 Refereed original research article in a scientific journal
The carbon-rich type Ic supernova 2016adj in the iconic dust lane of Centaurus A: Potential signatures of an interaction with circumstellar hydrogen
Authors: Stritzinger, M. D.; Baron, E.; Taddia, F.; Burns, C. R.; Fraser, M.; Galbany, L.; Holmbo, S.; Hoeflich, P.; Morrell, N.; Arndt, L. S.; Hsiao, E. Y.; Johansson, J. P.; Karamehmetoglu, E.; Kuncarayakti, H.; Lyman, J.; Moriya, T. J.; Phan, K.; Phillips, M. M.; Anderson, J. P.; Ashall, C.; Brown, P. J.; Castellon, S.; Della Valle, M.; Gonzalez-Gaitan, S.; Gromadzki, M.; Handberg, R.; Lu, J.; Nicholl, M.; Shahbandeh, M.
Publisher: EDP SCIENCES S A
Publishing place: LES ULIS CEDEX A
Publication year: 2024
Journal: Astronomy and Astrophysics
Journal name in source: ASTRONOMY & ASTROPHYSICS
Journal acronym: ASTRON ASTROPHYS
Article number: A79
Volume: 686
Number of pages: 30
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202347883
Web address : https://doi.org/10.1051/0004-6361/202347883
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/457180626
We present a comprehensive data set of supernova (SN) 2016adj located within the central dust lane of Centaurus A. SN 2016adj is significantly reddened and after correcting the peak apparent B-band magnitude (m(B) = 17.48 +/- 0.05) for Milky Way reddening and our inferred host-galaxy reddening parameters(i.e.,R-V(host)=5.7 +/- 0.7 and A(V)(host)=6.3 +/- 0.2 mag), we estimated it reached a peak absolute magnitude of M-B similar to -18. A detailed inspection of the optical and near-infrared (NIR) spectroscopic time series reveals a carbon-rich SN Ic and not a SN Ib/IIb as previously suggested in the literature. The NIR spectra show prevalent carbon-monoxide formation occurring already by +41 days past B-band maximum, which is approximate to 11 days earlier than previously reported in the literature for this object. Interestingly, around two months past maximum, the NIR spectrum of SN 2016adj begins to exhibit H features, with a +97 days medium resolution spectrum revealing both Paschen and Bracket lines with absorption minima of similar to 2000 km s(-1), full-width-half-maximum emission velocities of similar to 1000 km s(-1), and emission line ratios consistent with a dense emission region. We speculate that these attributes are due to a circumstellar interaction (CSI) between the rapidly expanding SN ejecta and a H-rich shell of material that formed during the pre-SN phase. A bolometric light curve was constructed and a semi-analytical model fit suggests the SN synthesized 0.5 M-circle dot of Ni-56 and ejected 4.7 M-circle dot of material, though these values should be approached with caution given the large uncertainties associated with the adopted reddening parameters and known light echo emission. Finally, inspection of the Hubble Space Telescope archival data yielded no progenitor detection.
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Funding information in the publication:
We appreciate constructive discussions with S. Bose and N. B. Suntzeff. The work of the CSP-II has been generously supported by the National Science Foundation under grants AST-1008343, AST-1613426, AST-1613455, and AST-1613472, and by the Danish Research Foundation via a Sapere Aude Fellowship. M.D.S. is supported by grants from the Independent Research Fund Denmark (IRFD; 8021-00170B and 10.46540/2032-00022B). 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. This work was funded in part by ANID, Millennium Science Initiative, ICN12_009. MN is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948381) and by UK Space Agency Grant No. ST/Y000692/1. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Facilities. Based on observations made with facilities at the Las Campanas Observatory including the Swope telescope, the du Pont telescope, and the Magellan telescopes. Data was also obtained with the ESO-La Silla NTT observatory (ESO programme IDs 191.D-0935 and 197.D-1075), the ESO-Paranal VLT (Programme IDs 094.B-0298 and 098.D-0540), and the ESO-Paranal VST (Program ID 60.A-9800). Finally, some data presented were obtained with the Swift Space Telescope. Software: This research made use of Astropy (Price-Whelan et al. 2018) and Photutils (Bradley et al. 2020). Photometry of SN 2016adj was computing using the Aarhus-Barcelona FLOWS projects automated photometry pipeline available for download on https://github.com/SNflows. HYDRA has been used to calculate the CO model spectra, and the gamma-ray transport (Höflich 1990, 2003, 2009; Hristov et al. 2021).
