Volume 602, June 2017
|Number of page(s)||22|
|Section||Stellar structure and evolution|
|Published online||24 May 2017|
The evolution of superluminous supernova LSQ14mo and its interacting host galaxy system ⋆
1 Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany
2 Argelander Institute for Astronomy, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
4 Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UK
5 Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
6 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching-bei-München, Germany
7 Division of Theoretical Astronomy, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, 181-8588 Tokyo, Japan
8 Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA
9 Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC), 3941 Pittsburgh, USA
10 Physics and Astronomy Department, University of Pittsburgh, Pittsburgh, PA 15260, USA
11 Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 76100 Rehovot, Israel
12 ESO, Karl-Schwarzschild-Strasse 2, 85748 Garching-bei-München, Germany
13 Institut d’Astrophysique de Paris, CNRS, and Université Pierre et Marie Curie, 98bis boulevard Arago, 75014 Paris, France
14 Physics Department, Yale University, 217 Prospect Street, New Haven, CT 06511-8499, USA
15 European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
16 Department of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK
Received: 29 November 2016
Accepted: 25 January 2017
We present and analyse an extensive dataset of the superluminous supernova (SLSN) LSQ14mo (z = 0.256), consisting of a multi-colour light curve from −30 d to +70 d in the rest-frame (relative to maximum light) and a series of six spectra from PESSTO covering −7 d to +50 d. This is among the densest spectroscopic coverage, and best-constrained rising light curve, for a fast-declining hydrogen-poor SLSN. The bolometric light curve can be reproduced with a millisecond magnetar model with ~ 4 M⊙ ejecta mass, and the temperature and velocity evolution is also suggestive of a magnetar as the power source. Spectral modelling indicates that the SN ejected ~ 6 M⊙ of CO-rich material with a kinetic energy of ~7 × 1051 erg, and suggests a partially thermalised additional source of luminosity between −2 d and +22 d. This may be due to interaction with a shell of material originating from pre-explosion mass loss. We further present a detailed analysis of the host galaxy system of LSQ14mo. PESSTO and GROND imaging show three spatially resolved bright regions, and we used the VLT and FORS2 to obtain a deep (five-hour exposure) spectra of the SN position and the three star-forming regions, which are at a similar redshift. The FORS2 spectrum at + 300 days shows no trace of SN emission lines and we place limits on the strength of [O i] from comparisons with other Ic supernovae. The deep spectra provides a unique chance to investigate spatial variations in the host star-formation activity and metallicity. The specific star-formation rate is similar in all three components,as is the presence of a young stellar population. However, the position of LSQ14mo exhibits a lower metallicity, with 12 + log (O/H) = 8.2 in both the R23 and N2 scales (corresponding to ~0.3 Z⊙ ). We propose that the three bright regions in the host system are interacting, which could induce gas flows triggering star formation in low-metallicity regions.
Key words: supernovae: general / supernovae: individual: LSQ14mo / galaxies: abundances / galaxies: dwarf / galaxies: interactions
© ESO, 2017
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