Superluminous supernovae: an explosive decade

Revealing the binary origin of Type Ic superluminous supernovae through nebular hydrogen emission

We propose that nebular H-alpha emission as detected in the Type Ic superluminous supernova iPTF13ehe stems from matter which is stripped from a companion star when the supernova ejecta collide with it. The temporal evolution, the line broadening, and the overall blueshift of the emission are consistent with this interpretation. We scale the nebular H-alpha luminosity predicted for Type Ia supernovae in single-degenerate systems to derive the stripped mass required to explain the H-alpha luminosity of iPTF13ehe. We find a stripped mass of 0.1 - 0.9 solar masses, assuming that the supernova lum…

Physics of Superluminous Supernovae

Understanding how massive stars die as supernovae is a crucial question in modern astrophysics. Supernovae are powerful stellar explosions and key drivers in the cosmic baryonic cycles by injecting their explosion energy and heavy elements to the interstellar medium that forms new stars. After decades of effort, astrophysicists have built up a stand model for the explosion mechanism of massive stars. However, this model is challenged by new kinds of stellar explosions discovered in the recent transit surveys. In particular, the new population called superluminous supernovae, which are a hundre…

探索伽马射线暴与超新星的联系：是否存在超亮超新星族群？

Exploring GRBs and supernovae connection: does a superluminous hypernova population exist?

本文回顾了超长伽马射线暴与超亮超新星之间可能存在的联系，重点分析了GRB 111209A/SN 2011kl等关键事件、前身星与宿主星系的作用以及磁星中心引擎等模型，指出需进一步观测和理论研究以确定是否存在超亮超新星族群。

Related progenitor models for long-duration gamma ray bursts and Type Ic superluminous supernovae

We model the late evolution and mass loss history of rapidly rotating Wolf-Rayet stars in the mass range $5\,\rm{M}_{\odot}\dots 100\,\rm{M}_{\odot}$. We find that quasi-chemically homogeneously evolving single stars computed with enhanced mixing retain very little or no helium and are compatible with Type\,Ic supernovae. The more efficient removal of core angular momentum and the expected smaller compact object mass in our lower mass models lead to core spins in the range suggested for magnetar driven superluminous supernovae. Our more massive models retain larger specific core angular moment…

Systematic investigation of the fallback accretion powered model for hydrogen-poor superluminous supernovae

The energy liberated by fallback accretion has been suggested as a possible engine to power hydrogen-poor superluminous supernovae. We systematically investigate this model using the Bayesian light-curve fitting code MOSFiT (Modular Open Source Fitter for Transients), fitting the light curves of 37 hydrogen-poor superluminous supernovae assuming a fallback accretion central engine. We find that this model can yield good fits to their light curves, with a fit quality that rivals the popular magnetar engine models. Examining our derived parameters for the fallback model, we find the total energy…

超亮超新星：多样的上升时间解释多样的光谱

Superluminous supernovae: diverse rise times explain diverse spectra

研究通过分析超亮超新星的光谱多样性，发现其光谱特征与喷射物温度及光曲线上升时间相关，提出新的诊断方法解释其光谱差异。

Magnetar-powered superluminous supernovae must first be exploded by jets

We analyze recent magnetar light-curve modeling of 38 hydrogen-poor superluminous supernovae (SLSNe), and find that the energies of the explosions themselves, that take place before the magnetar energy is released, are more than what the neutrino-driven explosion mechanism can supply for about half of the systems. These SLSNe must have been exploded by a different process than the delayed neutrino mechanism, most likely the jet feedback mechanism (JFM). The conclusion for magnetar modeling of SLSNe is that jets launched at magnetar birth cannot be ignored, not at the explosion itself and not l…

Magnetar-Powered Supernovae in Two Dimensions. I. Superluminous Supernovae

Previous studies have shown that the radiation emitted by a rapidly rotating magnetar embedded in a young supernova can greatly amplify its luminosity. These one-dimensional studies have also revealed the existence of an instability arising from the piling up of radiatively accelerated matter in a thin dense shell deep inside the supernova. Here we examine the problem in two dimensions and find that, while instabilities cause mixing and fracture this shell into filamentary structures that reduce the density contrast, the concentration of matter in a hollow shell persists. The extent of the mix…

利用中国空间站望远镜的超亮超新星对宇宙学约束的预测

Forecast of cosmological constraints with superluminous supernovae from the Chinese Space Station Telescope

本研究探讨了中国空间站望远镜（CSST）超亮超新星（SLSNe）的宇宙学应用，预测其在2.5年内可观测约360颗SLSNe，并利用峰值-颜色关系严格约束宇宙学参数，揭示高红移暗能量本质。

Pre-collapse Properties of Superluminous Supernovae and Long Gamma-Ray Burst Progenitor Models

We analyze the properties of 42 rapidly rotating, low metallicity, quasi-chemically homogeneously evolving stellar models in the mass range between 4 and 45 $\,\mathrm{M}_\odot$ at the time of core collapse. Such models were proposed as progenitors for both superluminous supernovae (SLSNe) and long duration gamma-ray bursts (lGRBs), and the Type Ic-BL supernovae (SNe) that are associated with them. Our findings suggest that whether these models produce a magnetar driven SLSN explosion or a near-critically rotating black hole (BH) is not a monotonic function of the initial mass. Rather, their e…

Properties of magnetars mimicking 56Ni-powered light curves in Type Ic superluminous supernovae

Many Type Ic superluminous supernovae have light-curve decline rates after their luminosity peak which are close to the nuclear decay rate of 56Co, consistent with the interpretation that they are powered by 56Ni and possibly pair-instability supernovae. However, their rise times are typically shorter than those expected from pair-instability supernovae, and Type Ic superluminous supernovae are often suggested to be powered by magnetar spin-down. If magnetar spin-down is actually a major mechanism to power Type Ic superluminous supernovae, it should be able to produce decline rates similar to …

A possible relation between flare activity in superluminous supernovae and gamma-ray bursts

Significant undulations appear in the light curve of a recently discovered super-luminous supernova (SLSN) SN 2015bn after the first peak, while the underlying profile of the light curve can be well explained by a continuous energy supply from a central engine, possibly the spin-down of a millisecond magnetar. We propose that these undulations are caused by an intermittent pulsed energy supply, indicating an energetic flare activity of the central engine of the SLSN. Many post-burst flares were discovered during X-ray afterglow observations of Gamma-Ray Bursts (GRBs). We find that the SLSN fla…

Constraining the ellipticity of strongly magnetized neutron stars powering superluminous supernovae

Superluminous supernovae (SLSNe) have been suggested to be powered by strongly magnetized, rapidly rotating neutron stars which are often called magnetars. In this process, rotational energy of the magnetar is radiated via magnetic dipole radiation and heats the supernova ejecta. However, if magnetars are highly distorted in their geometric shape, rotational energy is mainly lost as gravitational wave radiation and thus such magnetars cannot power SLSNe. By simply comparing electromagnetic and gravitational wave emission timescales, we constrain upper limits to the ellipticity of magnetars by …

Thermonuclear explosions of rapidly differentially rotating white dwarfs: Candidates for superluminous Type Ia supernovae?

The observed sub-class of "superluminous" Type Ia supernovae lacks a convincing theoretical explanation. If the emission of such objects were powered exclusively by radioactive decay of 56Ni formed in the explosion, a progenitor mass close to or even above the Chandrasekhar limit for a non-rotating white dwarf star would be required. Masses significantly exceeding this limit can be supported by differential rotation. We, therefore, explore explosions and predict observables for various scenarios resulting from differentially rotating carbon-oxygen white dwarfs close to their respective limit o…

Complexity in the light curves and spectra of slow-evolving superluminous supernovae

A small group of the newly discovered superluminous supernovae show broad and slowly evolving light curves. Here we present extensive observational data for the slow-evolving superluminous supernova LSQ14an, which brings this group of transients to four in total in the low redshift Universe (z$<$0.2; SN 2007bi, PTF12dam, SN 2015bn). We particularly focus on the optical and near-infrared evolution during the period from 50 days up to 400 days from peak, showing that they are all fairly similar in their light curve and spectral evolution. LSQ14an shows broad, blue-shifted [O III] $λλ$4959, 5007 …

A puzzle solved after two decades: SN 2002gh among the brightest of superluminous supernovae

We present optical photometry and spectroscopy of the superluminous SN 2002gh from maximum light to $+204$ days, obtained as part of the Carnegie Type II Supernova (CATS) project. SN 2002gh is among the most luminous discovered supernovae ever, yet it remained unnoticed for nearly two decades. Using Dark Energy Camera archival images we identify the potential SN host galaxy as a faint dwarf galaxy, presumably having low metallicity, and in an apparent merging process with other nearby dwarf galaxies. We show that SN 2002gh is among the brightest hydrogen-poor SLSNe with $M_{V} = -22.40 \pm 0.0…

超亮Ia型超新星的前身星

The Progenitors of Superluminous Type Ia Supernovae

本研究针对超钱德拉塞卡Ia型超新星的前身星问题，通过一维数值模拟对比磁化白矮星与白矮星并合模型，发现并合模型能更好重现观测的低抛射速度与光变特征，为后续观测和高维建模提供基础。

Analytical Expressions For Light-Curves Of Ordinary And Superluminous Supernovae Type Ia

Supernovae of type Ia (SNeIa) can be produced by the explosion of slowly-rotating carbon-oxygen white dwarfs whose mass increases beyond a critical value by mass accretion. Collision with circumstellar material during their photospheric and early nebular phase can enhance the bolometric luminosity of otherwise ordinary SNeIa to become superluminous. A few simplifying assumptions lead to a simple analytic master formula, which describes quite well the bolometric light-curves of ordinary SNeIa and supeluminous SNeIa in terms of few initial physical parameters. Other main properties of SNeIa, inc…

Spectropolarimetry of superluminous supernovae: insight into their geometry

We present the first spectropolarimetric observations of a hydrogen-free superluminous supernova at z=0.1136, namely SN 2015bn. The transient shows significant polarization at both the observed epochs: one 24 days before maximum light in the rest-frame, and the subsequent at 27 days after peak luminosity. Analysis of the Q-U plane suggests the presence of a dominant axis and no physical departure from the main axis at either epoch. The polarization spectrum along the dominant axis is characterized by a strong wavelength dependence and an increase in the signal from the first to the second epoc…

First release of high-redshift superluminous supernovae from the Subaru HIgh-Z sUpernova CAmpaign (SHIZUCA). II. Spectroscopic properties

We present Keck spectroscopic observations of three probable high redshift superluminous supernovae (SLSNe) from the Subaru HIgh-Z sUpernova CAmpaign (SHIZUCA), confirming redshifts of 1.851, 1.965 and 2.399. The host galaxies were selected for transient monitoring from multi-band photometric redshifts. The supernovae are detected during their rise, and the classically scheduled spectra are collected near maximum light. The restframe far-ultraviolet (FUV;$\sim$1000A-2500A) spectra include a significant host galaxy flux contribution and we compare our host galaxy subtracted spectra to UV-lumino…

On the event rate and luminosity function of superluminous supernovae

We calculate the rate per unit volume of hydrogen-poor superluminous supernovae (SLSNe-I) based on the 17 events discovered with the Pan-STARRS1 Medium Deep Survey (PS1 MDS). Two forms of the luminosity function (LF) are assumed : a log-normal form and a single power-law form, respectively. The rate of SLSNe-I is assumed to be proportional to the cosmic star formation rate with an additional redshift evolution of $(1+z)^α$. Our results show that the single power-low form fits the data better than the log-normal form, and the event rate of SLSNe-I is proportional to the cosmic star formation ra…

The superluminous SN DES13S2cmm as a signature of a Quark-Nova in a He-HMXB system

We show that by appealing to a Quark-Nova (the explosive transition of a neutron star to a quark star) occurring in an He-HMXB system we can account for the lightcurve of the first superluminous SN, DES13S2cmm, discovered by the Dark-Energy Survey. The neutron star's explosive conversion is triggered as a result of accretion during the He-HMXB second Common Envelope phase. The dense, relativistic, Quark-Nova ejecta in turn energizes the extended He-rich Common Envelope in an inside-out shock heating process. We find an excellent fit (reduced chi^2 of 1.09) to the bolometric light-curve of SN D…

A Mid-infrared Study of Superluminous Supernovae

We present the mid-infrared (MIR) light curves (LC) of 10 superluminous supernovae (SLSNe) at $z<0.12$ based on WISE data at 3.4 and 4.6 $μ$m. Three of them, including PS15br, SN 2017ens, and SN 2017err show rebrightening which started at 200--400 days and ended at 600--1000 days, indicating the presence of dust. In four of the left seven SLSNe, dust emission was detected with monochromatic luminosities of $10^7\sim10^8\ L_\odot$ at epochs of 100--500 days based on MIR colors $W1-W2\sim1$. Among the three SLSNe which show rebrightening, we further analysed PS15br and SN 2017ens. We modeled the…

Long-duration superluminous supernovae at late times

Nebular-phase observations and spectral models of Type Ic superluminous supernovae are presented. LSQ14an and SN 2015bn both display late-time spectra similar to galaxy-subtracted spectra of SN 2007bi, and the class shows strong similarity with broad-lined Type Ic SNe such as SN 1998bw. Near-infrared observations of SN 2015bn show a strong Ca II triplet, O I 9263, O I 1.13 um and Mg I 1.50 um, but no distinct He, Si, or S emission. The high Ca II NIR/[Ca II] 7291,7323 ratio of ~2 indicates a high electron density of n_e >~ 10^8 cm^{-3}. Spectral models of oxygen-zone emission are investigated …

Luminous Supernovae: Unveiling a Population Between Superluminous and Normal Core-collapse Supernovae

Stripped-envelope core-collapse supernovae can be divided into two broad classes: the common Type Ib/c supernovae (SNe Ib/c), powered by the radioactive decay of $^{56}$Ni, and the rare superluminous supernovae (SLSNe), most likely powered by the spin-down of a magnetar central engine. Up to now, the intermediate regime between these two populations has remained mostly unexplored. Here, we present a comprehensive study of 40 \textit{luminous supernovae} (LSNe), SNe with peak magnitudes of $M_r = -19$ to $-20$ mag, bound by SLSNe on the bright end and by SNe Ib/c on the dim end. Spectroscopical…

Light curves of hydrogen-poor Superluminous Supernovae from the Palomar Transient Factory

We investigate the light-curve properties of a sample of 26 spectroscopically confirmed hydrogen-poor superluminous supernovae (SLSNe-I) in the Palomar Transient Factory (PTF) survey. These events are brighter than SNe Ib/c and SNe Ic-BL, on average, by about 4 and 2~mag, respectively. The peak absolute magnitudes of SLSNe-I in rest-frame $g$ band span $-22\lesssim M_g \lesssim-20$~mag, and these peaks are not powered by radioactive $^{56}$Ni, unless strong asymmetries are at play. The rise timescales are longer for SLSNe than for normal SNe Ib/c, by roughly 10 days, for events with similar de…

Can pair-instability supernova models match the observations of superluminous supernovae?

An increasing number of so-called superluminous supernovae (SLSNe) are discovered. It is believed that at least some of them with slowly fading light curves originate in stellar explosions induced by the pair instability mechanism. Recent stellar evolution models naturally predict pair instability supernovae (PISNe) from very massive stars at wide range of metallicities (up to Z=0.006, Yusof et al. 2013). In the scope of this study we analyse whether PISN models can match the observational properties of SLSNe with various light curve shapes. Specifically, we explore the influence of different …

On the nature of Hydrogen-rich Superluminous Supernovae

We present two hydrogen-rich superluminous supernovae (SLSNe), namely SN2013hx and PS15br. These objects, together with SN2008es are the only SLSNe showing a distinct, broad Halpha feature during the photospheric phase and also do not show any sign of strong interaction between fast-moving ejecta and circumstellar shells in their early spectra. Despite PS15br peak luminosity is fainter than the other two objects, the spectrophotometric evolution is similar to SN2013hx and different than any other supernova in a similar luminosity space. We group all of them as SLSNe II and hence distinct from …

The magnetar model for Type I superluminous supernovae I: Bayesian analysis of the full multicolour light curve sample with MOSFiT

We use the new Modular Open Source Fitter for Transients (MOSFiT) to model 38 hydrogen-poor superluminous supernovae (SLSNe). We fit their multicolour light curves with a magnetar spin-down model and present the posterior distributions of magnetar and ejecta parameters. The colour evolution can be well matched with a simple absorbed blackbody. We find the following medians (1$σ$ ranges): spin period 2.4 ms (1.2-4 ms); magnetic field $0.8\times 10^{14}$ G (0.2-1.8 $\times 10^{14}$ G); ejecta mass 4.8 Msun (2.2-12.9 Msun); kinetic energy $3.9\times 10^{51}$ erg (1.9-9.8 $\times 10^{51}$ erg). Th…

The Energy Sources of Superluminous Supernovae

Supernovae (SNe) are the most brilliant optical stellar-class explosions. Over the past two decades, several optical transient survey projects discovered more than $\sim 100$ so-called superluminous supernovae (SLSNe) whose peak luminosities and radiated energy are $\gtrsim 7\times 10^{43}$ erg s$^{-1}$ and $\gtrsim 10^{51}$ erg, at least an order of magnitude larger than that of normal SNe. According to their optical spectra features, SLSNe have been split into two broad categories of type I that are hydrogen-deficient and type II that are hydrogen-rich. Investigating and determining the ener…

Superluminous X-rays from a superluminous supernova

The discovery of a population of superluminous supernovae (SLSNe), with peak luminosities a factor of ~100 brighter than normal SNe (typically SLSNe have M_V <-21), has shown an unexpected diversity in core-collapse supernova properties. Numerous models have been postulated for the nature of these events, including a strong interaction of the shockwave with a dense circumstellar environment, a re-energizing of the outflow via a central engine, or an origin in the catastrophic destruction of the star following a loss of pressure due to pair production in an extremely massive stellar core (so-ca…

Pre-maximum spectroscopic diversity of hydrogen-poor superluminous supernovae

We search for the reasons behind the spectroscopic diversity of hydrogen-poor superluminous supernovae (SLSNe-I) in the pre-maximum phase. Our analysis is a continuation of the paper of \citet{ktr21}, who disclosed two new subtypes of SLSNe-I characterized by the presence/absence of a W-shaped absorption feature in their pre-maximum spectra between 4000 and 5000 Å(called Type~W and Type~15bn, respectively). However, the physical cause of this bimodality is still uncertain. Here we present pre-maximum spectral synthesis of 27 SLSNe-I with special attention to the photospheric temperature ($T_{ …

On the early-time excess emission in hydrogen-poor superluminous supernovae

We present the light curves of the hydrogen-poor superluminous supernovae (SLSNe-I) PTF12dam and iPTF13dcc, discovered by the (intermediate) Palomar Transient Factory. Both show excess emission at early times and a slowly declining light curve at late times. The early bump in PTF12dam is very similar in duration (~10 days) and brightness relative to the main peak (2-3 mag fainter) compared to those observed in other SLSNe-I. In contrast, the long-duration (>30 days) early excess emission in iPTF13dcc, whose brightness competes with that of the main peak, appears to be of a different nature. We…

Hydrogenless Superluminous Supernova PTF12dam in the Model of an Explosion inside an Extended Envelope

A model of a supernova explosion inside a dense extended hydrogenless envelope is proposed to explain the properties of the light curve for one of the superluminous supernovae PTF12dam. It is argued in the literature that the flux of this supernova rises too fast to be explained by the explosion model due to the instability associated with the electron-positron pair production (pair-instability supernova, PISNe), but it is well described by the models with energy input by a magnetar. We show that the PTF12dam-type supernovae can be explained without a magnetar in a model with a radiative shock…

Transitional events in the spectrophotometric regime between stripped envelope and superluminous supernovae

The division between stripped-envelope supernovae (SE-SNe) and superluminous supernovae (SLSNe) is not well defined in either photometric or spectroscopic space. While a sharp luminosity threshold has been suggested, there remains an increasing number of transitional objects that reach this threshold without the spectroscopic signatures common to SLSNe. In this work we present data and analysis on four SNe transitional between SE-SNe and SLSNe; the He-poor SNe 2019dwa and 2019cri, and the He-rich SNe 2019hge and 2019unb. Each object displays long-lived and variable photometric evolution with l…

Magnetar Models of Superluminous Supernovae from the Dark Energy Survey: Exploring Redshift Evolution

Superluminous supernovae (SLSNe) are luminous transients that can be detected to high redshifts with upcoming optical time-domain surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). An interesting open question is whether the properties of SLSNe evolve through cosmic time. To address this question, in this paper we model the multi-color light curves of all 21 Type I SLSNe from the Dark Energy Survey (DES) with a magnetar spin-down engine, implemented in the Modular Open Source Fitter for Transients (MOSFiT). With redshifts up to $z\approx 2$, this sample inclu…

The restframe ultraviolet of superluminous supernovae -- I. Potential as cosmological probes

Superluminous supernovae (SLSNe) have been detected to $z\sim4$ and can be detected to $z\gtrsim15$ using current and upcoming facilities. SLSNe are extremely UV luminous, and hence objects at $z\gtrsim7$ are detected exclusively via their rest-frame UV using optical and infrared facilities. SLSNe have great utility in multiple areas of stellar and galactic evolution. Here, we explore the potential use of SLSNe type-I as high-redshift cosmological distance indicators in their rest-frame UV. Using a SLSNe-I sample in the redshift range $1\lesssim z\lesssim 3$, we investigate correlations betwee…

A statistical approach to identify superluminous supernovae and probe their diversity

We investigate the identification of hydrogen-poor superluminous supernovae (SLSNe I) using a photometric analysis, without including an arbitrary magnitude threshold. We assemble a homogeneous sample of previously classified SLSNe I from the literature, and fit their light curves using Gaussian processes. From the fits, we identify four photometric parameters that have a high statistical significance when correlated, and combine them in a parameter space that conveys information on their luminosity and color evolution. This parameter space presents a new definition for SLSNe I, which can be u…

磁星驱动的超亮超新星光变特征：结合引力波发射与高能泄漏

Lightcurve Features of Magnetar-Powered Superluminous Supernovae with Gravitational-Wave Emission and High-Energy Leakage

本研究探讨了引力波发射和高能泄漏对超亮超新星光变曲线的影响，发现毫秒磁星的联合作用会抑制早期亮度并增强晚期发射。

Nebular-phase spectra of superluminous supernovae: physical insights from observational and statistical properties

We study the spectroscopic evolution of superluminous supernovae (SLSNe) later than 100 days after maximum light. We present new data for Gaia16apd and SN2017egm, and analyse these with a larger sample comprising 41 spectra of 12 events. The spectra become nebular within 2-4 $e$-folding times after light curve peak, with the rate of spectroscopic evolution correlated to the light curve timescale. Emission lines are identified with well-known transitions of oxygen, calcium, magnesium, sodium and iron. SLSNe are differentiated from other Type Ic SNe by a prominent O I $λ$7774 line and higher-ion…

The Volumetric Rate of Superluminous Supernovae at z~1

We present a measurement of the volumetric rate of superluminous supernovae (SLSNe) at z~1, measured using archival data from the first four years of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We develop a method for the photometric classification of SLSNe to construct our sample. Our sample includes two previously spectroscopically-identified objects, and a further new candidate selected using our classification technique. We use the point-source recovery efficiencies from Perrett et.al. (2010) and a Monte Carlo approach to calculate the rate based on our SLSN sample. …

The Zwicky Transient Facility phase I sample of hydrogen-rich superluminous supernovae without strong narrow emission lines

We present a sample of 14 hydrogen-rich superluminous supernovae (SLSNe II) from the Zwicky Transient Facility (ZTF) between 2018 and 2020. We include all classified SLSNe with peaks $M_{g}<-20$ mag and with observed \emph{broad} but not narrow Balmer emission, corresponding to roughly 20 per cent of all hydrogen-rich SLSNe in ZTF phase I. We examine the light curves and spectra of SLSNe II and attempt to constrain their power source using light-curve models. The brightest events are photometrically and spectroscopically similar to the prototypical SN 2008es, while others are found spectroscop…

Bumpy Declining Light Curves Are Common in Hydrogen-poor Superluminous Supernovae

Recent work has revealed that the light curves of hydrogen-poor (Type I) superluminous supernovae (SLSNe), thought to be powered by magnetar central engines, do not always follow the smooth decline predicted by a simple magnetar spin-down model. Here we present the first systematic study of the prevalence and properties of "bumps" in the post-peak light curves of 34 SLSNe. We find that the majority (44-76%) of events cannot be explained by a smooth magnetar model alone. We do not find any difference in supernova properties between events with and without bumps. By fitting a simple Gaussian mod…

I型超新星的伽马射线效率：潜在探测和群体层面的限制

On the Gamma-ray Efficiency of Superluminous Supernovae: Potential Detections and Population-Level Constraints

研究通过分析17年费米-拉特数据，发现I型超新星的伽马射线效率显著低于预测，SN 2017egm显示可能的超额，但SN 2018bsz的未探测结果排除了简单统一效率模型，提示潜在的多样性。

Stellar Core-Merger-Induced Collapse: New Formation Pathways for Black Holes, Thorne-$\dot{\rm Z}$ytkow objects, Magnetars and Superluminous Supernovae

Most neutron stars (NSs) and black holes (BHs) are believed to be the final remnants in the evolution of massive stars. In this study, we propose a new formation channel for the formation of BHs and peculiar NSs (specifically, magnetars and Thorne-$\dot{\rm Z}$ytkow objects [T$\dot{\rm Z}$Os]), which we refer to as the core merger-induced collapse (CMIC) model. This model involves the merger at the end of a common-envelope phase of an oxygen/neon/magnesium composition white dwarf and the core of a hydrogen-rich or helium-rich non-degenerate star, leading to the creation of peculiar new types o…

I型超亮超新星光谱中W形O II线的形成机制研究

On the Formation of the W-shaped O II Lines in Spectra of Type I Superluminous Supernovae

本文通过系统计算八颗I型超亮超新星的合成光谱，发现W形O II线的形成无需强烈偏离星云近似，且其出现对温度敏感（约14,000–16,000 K），并据此约束了非热电离率，为SLSNe-I能量来源提供了独立限制。

Millisecond Magnetar Birth Connects FRB 121102 to Superluminous Supernovae and Long Duration Gamma-ray Bursts

Sub-arcsecond localization of the repeating fast radio burst FRB 121102 revealed its coincidence with a dwarf host galaxy and a steady (`quiescent') non-thermal radio source. We show that the properties of the host galaxy are consistent with those of long-duration gamma-ray bursts (LGRB) and hydrogen-poor superluminous supernovae (SLSNe-I). Both LGRBs and SLSNe-I were previously hypothesized to be powered by the electromagnetic spin-down of newly-formed, strongly-magnetized neutron stars with millisecond birth rotation periods (`millisecond magnetars'). This motivates considering a scenario wh…

Testing the magnetar scenario for superluminous supernovae with circular polarimetry

Superluminous supernovae (SLSNe) are at least $\sim$5 times more luminous than common supernovae (SNe). Especially hydrogen-poor SLSN-I are difficult to explain with conventional powering mechanisms. One possible scenario that might explain such luminosities is that SLSNe-I are powered by an internal engine, such as a magnetar or an accreting black hole. Strong magnetic fields or collimated jets can circularly polarize light. In this work, we measured circular polarization of two SLSNe-I with the FOcal Reducer and low dispersion Spectrograph (FORS2) mounted at the ESO's Very Large Telescope (V…

Simulations of light curves and spectra for superluminous Type Ic supernovae powered by magnetars

Numerous superluminous supernovae (SLSNe) of Type Ic have been discovered and monitored in the last decade. The favored mechanism at their origin is a sustained power injection from a magnetar. This study presents non-local thermodynamic equilibrium time-dependent radiative transfer simulations of various single carbon-rich Wolf-Rayet star explosions influenced by magnetars of diverse properties and covering from a few days to one or two years after explosion. Nonthermal processes are treated; the magnetar-power deposition profile is prescribed; dynamical effects are ignored. In this context, …

Spectra of Hydrogen-Poor Superluminous Supernovae from the Palomar Transient Factory

Most Type I superluminous supernovae (SLSNe-I) reported to date have been identified by their high peak luminosities and spectra lacking obvious signs of hydrogen. We demonstrate that these events can be distinguished from normal-luminosity SNe (including Type Ic events) solely from their spectra over a wide range of light-curve phases. We use this distinction to select 19 SLSNe-I and 4 possible SLSNe-I from the Palomar Transient Factory archive (including 7 previously published objects). We present 127 new spectra of these objects and combine these with 39 previously published spectra, and we…

Selecting superluminous supernovae in faint galaxies from the first year of the Pan-STARRS1 Medium Deep Survey

The Pan-STARRS1 (PS1) survey has obtained imaging in 5 bands (grizy_P1) over 10 Medium Deep Survey (MDS) fields covering a total of 70 square degrees. This paper describes the search for apparently hostless supernovae (SNe) within the first year of PS1 MDS data with an aim of discovering new superluminous supernovae (SLSNe). A total of 249 hostless transients were discovered down to a limiting magnitude of M_AB ~ 23.5, of which 76 were classified as Type Ia SNe. There were 57 SNe with complete light curves that are likely core-collapse SNe (CCSNe) or SLSNe and 12 of these have had spectra take…

A Search for Late-Time Radio Emission and Fast Radio Bursts from Superluminous Supernovae

We present results of a search for late-time radio emission and Fast Radio Bursts (FRBs) from a sample of type-I superluminous supernovae (SLSNe-I). We used the Karl G. Jansky Very Large Array to observe ten SLSN-I more than 5 years old at a frequency of 3 GHz. We searched fast-sampled visibilities for FRBs and used the same data to perform a deep imaging search for late-time radio emission expected in models of magnetar-powered supernovae. No FRBs were found. One SLSN-I, PTF10hgi, is detected in deep imaging, corresponding to a luminosity of $1.2\times10^{28}$ erg s$^{-1}$. This luminosity, c…

A Multiple Ejecta-Circumstellar Medium Interaction Model and Its Implications for Superluminous Supernovae iPTF15esb and iPTF13dcc

In this paper, we investigate two hydrogen-poor superluminous supernovae (SLSNe) iPTF15esb and iPTF13dcc whose light curves (LCs) show significant deviation from the smooth rise and fall. The LC of iPTF15esb exhibits two peaks and a post-peak plateau, and furthermore the late-time spectrum of iPTF15esb shows a strong, broad H$α$ emission line. The early-time LC of iPTF13dcc shows a long duration bump followed by the second peak. Here we propose an ejecta-circumstellar medium (CSM) interaction model involving multiple shells/winds and use it to explain the LCs of iPTF15esb and iPTF13dcc. We fin…

Predictions for signatures of the quark-nova in superluminous supernovae

[Abridged] Superluminous Supernovae (SN2006gy, SN2005gj, SN2005ap, SN2008fz, SN2003ma) have been a challenge to explain by standard models. We present an alternative scenario involving a quark-nova (QN), an explosive transition of the newly born neutron star to a quark star in which a second explosion (delayed) occurs inside the already expanding ejecta of a normal SN. The reheated SN ejecta can radiate at higher levels for longer periods of time primarily due to reduced adiabatic expansion losses, unlike the standard SN case. Our model is successfully applied to SN2006gy, SN2005gj, SN2005ap, …