Luminous Supernovae

Gal‐Yam, A.

doi:10.1126/science.1203601

Cited by 557 publications

(432 citation statements)

References 81 publications

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“…Expanding upon this and a number of authors have suggested that magnetars may power superluminous type II and Ibc SNe (Thompson et al 2004;Woosley 2010;Kasen & Bildsten 2010;Gal-Yam 2012;Quimby et al 2011); indeed the 7.29 M progenitor model of Woosley (2010) is directly motivated by the presence of J1647-45 within Wd1. Moreover, Inserra et al (2013) studied the late-time lightcurves of five superluminous type Ic SNe, finding that the data are indeed consistent with these events being powered by the rapid spin-down of newly born magnetars (see also McCrum et al 2013;Nicholl et al 2013) Additionally, magnetars have also been proposed as the central engines of some gamma-ray bursts (GRBs; e.g.…”

Section: Discussionmentioning

confidence: 99%

A VLT/FLAMES survey for massive binaries in Westerlund 1

Clark

Ritchie

Najarro

et al. 2014

A&A

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Context. The first soft gamma-ray repeater was discovered over three decades ago, and was subsequently identified as a magnetar, a class of highly magnetised neutron star. It has been hypothesised that these stars power some of the brightest supernovae known, and that they may form the central engines of some long duration gamma-ray bursts. However there is currently no consenus on the formation channel(s) of these objects. Aims. The presence of a magnetar in the starburst cluster Westerlund 1 implies a progenitor with a mass ≥40 M , which favours its formation in a binary that was disrupted at supernova. To test this hypothesis we conducted a search for the putative pre-SN companion.Methods. This was accomplished via a radial velocity survey to identify high-velocity runaways, with subsequent non-LTE model atmosphere analysis of the resultant candidate, Wd1-5. Results. Wd1-5 closely resembles the primaries in the short-period binaries, Wd1-13 and 44, suggesting a similar evolutionary history, although it currently appears single. It is overluminous for its spectroscopic mass and we find evidence of He-and N-enrichement, O-depletion, and critically C-enrichment, a combination of properties that is difficult to explain under single star evolutionary paradigms. We infer a pre-SN history for Wd1-5 which supposes an initial close binary comprising two stars of comparable (∼41 M + 35 M ) masses. Efficient mass transfer from the initially more massive component leads to the mass-gainer evolving more rapidly, initiating luminous blue variable/common envelope evolution. Reverse, wind-driven mass transfer during its subsequent WC Wolf-Rayet phase leads to the carbon pollution of Wd1-5, before a type Ibc supernova disrupts the binary system. Under the assumption of a physical association between Wd1-5 and J1647-45, the secondary is identified as the magnetar progenitor; its common envelope evolutionary phase prevents spin-down of its core prior to SN and the seed magnetic field for the magnetar forms either in this phase or during the earlier episode of mass transfer in which it was spun-up. Conclusions. Our results suggest that binarity is a key ingredient in the formation of at least a subset of magnetars by preventing spin-down via core-coupling and potentially generating a seed magnetic field. The apparent formation of a magnetar in a Type Ibc supernova is consistent with recent suggestions that superluminous Type Ibc supernovae are powered by the rapid spin-down of these objects.

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Section: Discussionmentioning

confidence: 99%

A VLT/FLAMES survey for massive binaries in Westerlund 1

Clark

Ritchie

Najarro

et al. 2014

A&A

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“…SLSNe are very luminous (M R < −21 mag) transients, probably arising from the explosion of very massive star (Quimby et al 2011;Gal-Yam 2012). In this case, it has been proposed that the first peak is powered by the post-shock cooling of extended stellar material (Nicholl et al 2015a;Piro 2015), whereas the main peak could be powered by a magnetar.…”

Section: Introductionmentioning

confidence: 99%

iPTF15dtg: a double-peaked Type Ic supernova from a massive progenitor

Taddia

Fremling

Sollerman

et al. 2016

A&A

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Context. Type Ic supernovae (SNe Ic) arise from the core-collapse of H-(and He-) poor stars, which could either be single Wolf-Rayet (WR) stars or lower-mass stars stripped of their envelope by a companion. Their light curves are radioactively powered and usually show a fast rise to peak (∼10−15 d), without any early (in the first few days) emission bumps (with the exception of broad-lined SNe Ic) as sometimes seen for other types of stripped-envelope SNe (e.g., Type IIb SN 1993J and Type Ib SN 2008D). Aims. We have studied iPTF15dtg, a spectroscopically normal SN Ic with an early excess in the optical light curves followed by a long (∼30 d) rise to the main peak. It is the first spectroscopically-normal double-peaked SN Ic to be observed. Our aim is to determine the properties of this explosion and of its progenitor star. Methods. Optical photometry and spectroscopy of iPTF15dtg was obtained with multiple telescopes. The resulting light curves and spectral sequence are analyzed and modeled with hydrodynamical and analytical models, with particular focus on the early emission. Results. iPTF15dtg is a slow rising SN Ic, similar to SN 2011bm. Hydrodynamical modeling of the bolometric properties reveals a large ejecta mass (∼10 M ) and strong 56 Ni mixing. The luminous early emission can be reproduced if we account for the presence of an extended ( 500 R ), low-mass ( 0.045 M ) envelope around the progenitor star. Alternative scenarios for the early peak, such as the interaction with a companion, a shock-breakout (SBO) cooling tail from the progenitor surface, or a magnetar-driven SBO are not favored. Conclusions. The large ejecta mass and the presence of H-and He-free extended material around the star suggest that the progenitor of iPTF15dtg was a massive ( 35 M ) WR star that experienced strong mass loss.

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“…Supernovae are defined as superluminous (SLSN) when they reach M V < −21 Gal-Yam 2012). The most luminous SLSNe observed have M V ∼ −22.5 (Gal-Yam 2012).…”

Section: Superluminous Supernovaementioning

confidence: 99%

Understanding extreme quasar optical variability with CRTS – I. Major AGN flares

Graham¹,

Djorgovski²,

Drake³

et al. 2017

Monthly Notices of the Royal Astronomical Society

119

133

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There is a large degree of variety in the optical variability of quasars and it is unclear whether this is all attributable to a single (set of) physical mechanism(s). We present the results of a systematic search for major flares in active galactic nucleus (AGN) in the Catalina Real-time Transient Survey as part of a broader study into extreme quasar variability. Such flares are defined in a quantitative manner as being atop of the normal, stochastic variability of quasars. We have identified 51 events from over 900 000 known quasars and high-probability quasar candidates, typically lasting 900 d and with a median peak amplitude of m = 1.25 mag. Characterizing the flare profile with a Weibull distribution, we find that nine of the sources are well described by a single-point single-lens model. This supports the proposal by Lawrence et al. that microlensing is a plausible physical mechanism for extreme variability. However, we attribute the majority of our events to explosive stellar-related activity in the accretion disc: superluminous supernovae, tidal disruption events and mergers of stellar mass black holes.

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Luminous Supernovae

Cited by 557 publications

References 81 publications

A VLT/FLAMES survey for massive binaries in Westerlund 1

A VLT/FLAMES survey for massive binaries in Westerlund 1

iPTF15dtg: a double-peaked Type Ic supernova from a massive progenitor

Understanding extreme quasar optical variability with CRTS – I. Major AGN flares

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