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

Nicholl, M.; Smartt, S. J.; Jerkstrand, A.; Inserra, C.; Sim, Stuart; Chen, Ting-Wan; Benetti, S.; Fraser, M.; Gal‐Yam, A.; Kankare, E.; Maguire, K.; Smith, Kenneth; Sullivan, M.; Valenti, S.; Young, D. R.; Baltay, C.; Bauer, F. E.; Baumont, S.; Bersier, D.; Botticella, M. T.; Childress, M.; Dennefeld, M.; Valle, M. Della; Elias‐Rosa, N.; Feindt, U.; Galbany, L.; Hadjiyska, E.; Guillou, L. Le; Leloudas, G.; Mazzali, P. A.; McKinnon, R.; Polshaw, J.; Rabinowitz, D.; Rostami, S.; Scalzo, R.; Schmidt, B.; Schulze, S.; Sollerman, J.; Taddia, F.; Yuan, F.

doi:10.1093/mnras/stv1522

Cited by 184 publications

(272 citation statements)

References 108 publications

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“…Determining the mass of the inner region has to rely on parametrised fits of the light curve, as we do not have nebular spectra. This has been done in many papers (e.g., Nicholl et al 2015). Considering the uncertainties (risetime, structure of the inner ejecta), results are in general agreement with ours.…”

Section: Discussionsupporting

confidence: 91%

Spectrum formation in superluminous supernovae (Type I)

Mazzali

Sullivan

Pian

et al. 2016

Mon. Not. R. Astron. Soc.

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The near-maximum spectra of most superluminous supernovae that are not dominated by interaction with a H-rich CSM (SLSN-I) are characterised by a blue spectral peak and a series of absorption lines which have been identified as O II. SN 2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/UV spectrum. Radiation transport methods are used to show that the spectra (not including SN 2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ∼ 10000 − 15000 km s −1 several lines form in the UV. O II lines, however, arise from very highly excited lower levels, which require significant departures from Local Thermodynamic Equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56 Ni decay. An appealing scenario is that they are energised by X-rays from the shock driven by a magnetar wind into the SN ejecta. The apparent lack of evolution of line velocity with time that characterises SLSNe up to about maximum is another argument in favour of the magnetar scenario. The smooth UV continuum of SN 2011kl requires higher ejecta velocities (∼ 20000 km s −1 ): line blanketing leads to an almost featureless spectrum. Helium is observed in some SLSNe after maximum. The high ionization near maximum implies that both He and H may be present but not observed at early times. The spectroscopic classification of SLSNe should probably reflect that of SNe Ib/c. Extensive time coverage is required for an accurate classification.

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Section: Discussionsupporting

confidence: 91%

Spectrum formation in superluminous supernovae (Type I)

Mazzali

Sullivan

Pian

et al. 2016

Mon. Not. R. Astron. Soc.

Self Cite

139

242

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“…SLSNI spectra with a conspicuous 6250 Å feature, i.e., similar to those observed for SN2007bi, LSQ12dlf, and iPTF13ehe, are frequently declared to be without a hydrogen feature or even so far as "hydrogen-free" (Gal-Yam et al 2009;Nicholl et al 2015;Yan et al 2015).…”

Section: Super-luminous Supernovaementioning

confidence: 87%

“…Without sufficient improvements from stripped-envelope models that produce signatures of Si IIλ6355, Nicholl et al (2014Nicholl et al ( , 2015 recently utilized SYNAPPS to identify Si II in the spectrum of another SLSNI, LSQ12dlf (shown near the top of Figure 9). The interpretation of Si II as the 6250 Å feature in LSQ12dlf is clearly inconsistent with the data from the redmost side of the emission component, through the absorption trough, and near the blue-most wing.…”

Section: Si Iiλ6355 As a Candidate Identificationmentioning

confidence: 99%

LINE IDENTIFICATIONS OF TYPE I SUPERNOVAE: ON THE DETECTION OF Si II FOR THESE HYDROGEN-POOR EVENTS

Parrent

Milisavljević

Söderberg

et al. 2016

ApJ

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Here we revisit line identifications of type I supernovae (SNe I) and highlight trace amounts of unburned hydrogen as an important free parameter for the composition of the progenitor. Most one-dimensional stripped-envelope models of supernovae indicate that observed features near 6000-6400 Å in typeI spectra are due to more than Si IIλ6355. However, while an interpretation of conspicuous Si IIλ6355 can approximate 6150 Å absorption features for all SNe Ia during the first month of free expansion, similar identifications applied to 6250 Å features of SNe Ib and Ic have not been as successful. When the corresponding synthetic spectra are compared with highquality timeseries observations, the computed spectra are frequently too blue in wavelength. Some improvement can be achieved with Fe II lines that contribute redward of 6150 Å; however, the computed spectra either remain too blue or the spectrum only reaches a fair agreement when the rise-time to peak brightness of the model conflicts with observations by a factor of two. This degree of disagreement brings into question the proposed explosion scenario. Similarly, a detection of strong Si IIλ6355 in the spectra of broadlined Ic and super-luminous events of type I/R is less convincing despite numerous model spectra used to show otherwise. Alternatively, we suggest 6000-6400 Å features are possibly influenced by either trace amounts of hydrogen or blueshifted absorption and emission in Hα, the latter being an effect which is frequently observed in the spectra of hydrogen-rich, SNe II.

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“…The lightcurves of SLSNe type I span a wide range of rise (∼ 15-40 d) and decline timescales (∼ 30-100 d). These may form two separate subclasses of slowly-and fast-declining objects (with a paucity of events at the midpoints of these ranges), but, with the current small sample size, they are also consistent with a continuous distribution (see Nicholl et al 2015a). The second group is that of hydrogen-rich SLSNe (SLSNe II).…”

Section: Introductionmentioning

confidence: 94%

“…2.3). Observations of LSQ14mo were first presented by Nicholl et al (2015a), who included the r-band and pseudo bolometric lightcurve in their statistical sample of SLSNe. Furthermore, in Leloudas et al (2015a), as part of the first polarimetric study of a SLSN, they found there is no evidence for significant deviations from spherical symmetry of LSQ14mo.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

Nicholl

Smartt

et al. 2017

A&A

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We present and analyse an extensive dataset of the superluminous supernova (SLSN) LSQ14mo (z = 0.256), consisting of a multicolour lightcurve 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 lightcurve, for a fast-declining hydrogenpoor SLSN. The bolometric lightcurve 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 × 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 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 R 23 and N2 scales (corresponding to ∼ 0.3 Z ). We propose that the three bright regions in the host system are interacting, which thus triggers star formation and forms young stellar populations.

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

Cited by 184 publications

References 108 publications

Spectrum formation in superluminous supernovae (Type I)

Spectrum formation in superluminous supernovae (Type I)

LINE IDENTIFICATIONS OF TYPE I SUPERNOVAE: ON THE DETECTION OF Si II FOR THESE HYDROGEN-POOR EVENTS

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

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