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. Kruehler, Y. -C. Pan, R. Kotak, L. Galbany, P. Schady, P. Wiseman, J. Greiner, S. Schulze, A. W. S. Man, A. Jerkstrand, K. W. Smith, M. DennefeldC. Baltay, J. Bolmer, E. Kankare, F. Knust, K. Maguire, D. Rabinowitz, S. Rostami, M. Sullivan, D. R. Young

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We present and analyse an extensive dataset of the superluminous supernova (SLSN) LSQ14mo (z = 0.256), consisting of a multi-colour lightcurve from -30 d to +70 d in the rest-frame and a series of 6 spectra from PESSTO covering -7 d to +50 d. This is among the densest spectroscopic coverage, and best-constrained rising lightcurve, for a fast-declining hydrogen-poor SLSN. The bolometric lightcurve can be reproduced with a millisecond magnetar model with ~ 4 M_sol 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_sol of CO-rich material with a kinetic energy of ~ 7 x 10^51 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 FORS 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 SNe. 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_sol). We propose that the three bright regions in the host system are interacting, which thus triggers star-formation and forms young stellar populations.
Original languageUndefined/Unknown
JournalAstronomy & Astrophysics
Publication statusPublished - Jun 2017


  • astro-ph.SR
  • astro-ph.GA
  • astro-ph.HE

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