The evolution of superluminous supernova LSQ14mo and its interacting host galaxy system

T. W. Chen, M. Nicholl, S. J. Smartt, P. A. Mazzali, R. M. Yates, T. J. Moriya, C. Inserra, N. Langer, T. Krühler, R. Kotak, L. Galbany, P. Schady, P. Wiseman, J. Greiner, S. Schulze, A. W.S. Man, A. Jerkstrand, K. W. Smith, M. Dennefeld, C. BaltayJ. Bolmer, E. Kankare, F. Knust, D. Rabinowitz, S. Rostami, M. Sullivan, D. R. Young

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)

Abstract

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.

Original languageEnglish
Article numberA9
JournalAstronomy and Astrophysics
Volume602
DOIs
Publication statusPublished - 01 Jun 2017

Keywords

  • Galaxies: Abundances
  • Galaxies: dwarf
  • Galaxies: interactions
  • Supernovae: general
  • Supernovae: individual: LSQ14mo

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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