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On the diversity of superluminous supernovae: ejected mass as the dominant factor

Nicholl, M and Smartt, SJ and Jerkstrand, A and Inserra, C and Sim, SA and Chen, T-W and Benetti, S and Fraser, M and Gal-Yam, A and Kankare, E and Maguire, K and Smith, K and Sullivan, M and Valenti, S and Young, DR and Baltay, C and Bauer, FE and Baumont, S and Bersier, D and Botticella, M-T and Childress, M and Dennefeld, M and Della Valle, M and Elias-Rosa, N and Feindt, U and Galbany, L and Hadjiyska, E and Le Guillou, L and Leloudas, G and Mazzali, PA and McKinnon, R and Polshaw, J and Rabinowitz, D and Rostami, S and Scalzo, R and Schmidt, BP and Schulze, S and Sollerman, J and Taddia, F and Yuan, F (2015) On the diversity of superluminous supernovae: ejected mass as the dominant factor. Monthly Notices of the Royal Astronomical Society, 452 (4). pp. 3869-3893. ISSN 0035-8711

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Abstract

We assemble a sample of 24 hydrogen-poor superluminous supernovae (SLSNe). Parameterizing the light-curve shape through rise and decline time-scales shows that the two are highly correlated. Magnetar-powered models can reproduce the correlation, with the diversity in rise and decline rates driven by the diffusion time-scale. Circumstellar interaction models can exhibit a similar rise–decline relation, but only for a narrow range of densities, which may be problematic for these models. We find that SLSNe are approximately 3.5 mag brighter and have light curves three times broader than SNe Ibc, but that the intrinsic shapes are similar. There are a number of SLSNe with particularly broad light curves, possibly indicating two progenitor channels, but statistical tests do not cleanly separate two populations. The general spectral evolution is also presented. Velocities measured from Fe II are similar for SLSNe and SNe Ibc, suggesting that diffusion time differences are dominated by mass or opacity. Flat velocity evolution in most SLSNe suggests a dense shell of ejecta. If opacities in SLSNe are similar to other SNe Ibc, the average ejected mass is higher by a factor 2–3. Assuming κ = 0.1 cm2 g−1, we estimate a mean (median) SLSN ejecta mass of 10 M⊙ (6 M⊙), with a range of 3–30 M⊙. Doubling the assumed opacity brings the masses closer to normal SNe Ibc, but with a high-mass tail. The most probable mechanism for generating SLSNe seems to be the core collapse of a very massive hydrogen-poor star, forming a millisecond magnetar.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record MNRAS (October 01, 2015) 452 (4): 3869-3893. is available online at: http://dx.doi.org/10.1093/mnras/stv1522
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 09 Feb 2016 09:55
Last Modified: 09 Feb 2016 09:55
DOI or Identification number: 10.1093/mnras/stv1522
URI: http://researchonline.ljmu.ac.uk/id/eprint/2873

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