Luminosity evolution of some stripped-envelope supernovae such as Type I superluminous supernovae is difficult to be explained by the canonical 56Ni nuclear decay heating. A popular alternative heating source is rapid spin down of strongly-magnetized rapidly-rotating neutron stars (magnetars). Recent observations have indicated that Type I superluminous supernovae often have bumpy light curves with multiple luminosity peaks. The cause of bumpy light curves is unknown. In this study, we investigate the possibility that the light-curve bumps are caused by variations of the thermal energy injection from magnetar spin down. We find that a temporal increase in the thermal energy injection can lead to multiple luminosity peaks. The multiple luminosity peaks caused by the variable thermal energy injection is found to be accompanied by significant increase in photospheric temperature, and photospheric radii are not significantly changed. We show that the bumpy light curves of SN 2015bn and SN 2019stc can be reproduced by temporarily increasing magnetar spin-down energy input by a factor of 2-3 for 5-20 days. However, not all the light-curve bumps are accompanied by the clear photospheric temperature increase as predicted by our synthetic models. In particular, the secondary light-curve bump of SN 2019stc is accompanied by a temporal increase in photospheric radii rather than temperature, which is not seen in our synthetic models. We, therefore, conclude that not all the light-curve bumps observed in luminous supernovae are caused by the variable thermal energy injection from magnetar spin down and some bumps are likely caused by a different mechanism.
The central engines of some superluminous supernovae (SLSNe) are generally suggested to be newly born fast rotating magnetars, which spin down mainly through magnetic dipole radiation and gravitational wave emission. We calculate the magnetar-powered SLSNe light curves (LCs) with the tilt angle evolution of newly born magnetars involved. We show that, depending on the internal toroidal magnetic fields ${\bar B}_{\rm t}$, the initial spin periods $P_{\rm i}$, and the radii $R_{\rm DU}$ of direct Urca (DU) cores of newly born magnetars, as well as the critical temperature $T_{\rm c}$ for $^3P_2$…
Both the long-duration gamma-ray bursts (LGRBs) and the Type I superluminous supernovae (SLSNe~I) have been proposed to be primarily powered by central magnetars. A correlation, proposed between the initial spin period ($P_0$) and the surface magnetic field ($B$) of the magnetars powering the X-ray plateaus in LGRB afterglows, indicates a possibility that the magnetars have reached an equilibrium spin period due to the fallback accretion. The corresponding accretion rates are inferred as $\dot{M}\approx10^{-4}-10^{-1}$ M$_\odot$ s$^{-1}$, and this result holds for the cases of both isotropic a…
The discovery of early bumps in some type-I superluminous supernovae (SLSNe-I) before the main peaks offers an important clue to their energy source mechanisms. In this paper, we updated an analytic magnetar-powered model for fitting the multi-band light curves of double-peaked SLSNe-I: the early bump is powered by magnetar-driven shock breakout thermal emission, and the main peak is powered by a radiative diffusion through the SN ejecta as in the standard magnetar-powered model. Generally, the diffusive luminosity is greater than the shock breakout luminosity at the early time, which makes th…
We address the issue of the postmaximum bump observed in the light curve of some superluminous supernovae. We rule out the popular mechanism of a circumstellar interaction suggested for the bump explanation. Instead we propose that the postmaximum bump is caused by the magnetar dipole field enhancement several months after the explosion. The modeling of SN 2019stc light curve based on the thin shell approximation implies that at the age of $\sim 90$ days the initial dipole magnetic field should be amplified by a factor of 2.8 to account for the postmaximum bump. The specific mechanism for the …
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…
A subset of short gamma-ray bursts (sGRBs) have been found to be characterized by near-infrared/optical bumps at $\sim 1$ days, some of which exhibit almost concurrent X-ray flares. Although the near-infrared/optical bumps may be a signature of kilonovae, the X-ray flares are not consistent with kilonovae. It is widely believed that sGRBs are produced by the mergers of double compact objects, during which sub-relativistic ejecta are launched. In this paper we propose that the above optical/X-ray features are indicative of the formation of long-lived magnetars following the mergers of double ne…
Magnetar Engines in Broad-lined Type Ic Supernovae and a Unified Picture for Magnetar-powered Stripped-envelope Supernovae
The Hong Kong Institute for Astronomy and Astrophysics, The University of Hong Kong（香港天文台及天体物理研究所，香港大学）；Department of Physics, The University of Hong Kong（香港大学物理系）；School of Physics and Astronomy, Monash University（蒙纳士大学物理与天文学院）；OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery（OzGrav：ARC引力波发现卓越中心）；The Nevada Center for Astrophysics and Department of Physics and Astronomy, University of Nevada, Las Vegas（内华达天体物理中心及内华达大学拉斯维加斯分校物理与天文系）
Ultra-long gamma-ray bursts (ulGRBs) are a new population of GRBs with extreme durations of $\sim 10^{4}$ s. Leading candidates for their origin are blue supergiant collapsars, magnetars, and white dwarf tidal disruption events (WD-TDEs) caused by massive black holes (BHs). Recent observations of supernova-like (SN-like) bumps associated with ulGRBs challenged both the WD-TDE and the blue supergiant models because of the detection of SNe and the absence of hydrogen lines, respectively. We propose that WD-TDEs can accommodate the observed SN-like bumps if the fallback WD matter releases energy …
We study 31 luminous, rapidly evolving optical transients (REOTs), and use the magnetar model and the ejecta--circumstellar-matter (CSM) interaction (CSI) model to fit their multiband light curves. We find that 28 events can be fitted by the magnetar model. and the derived masses ($\sim0.05$--5.58\,M$_\odot$) are consistent with that of stripped and ultrastripped core-collapse supernovae (CCSNe). On the other hand, the CSI model can fit 25 events; the derived ejecta masses are $\sim 3$--30\,M$_\odot$, consistent with that of SNe~Ibn. The results, together with the fact that many luminous REOTs…
Ultra-long-duration gamma-ray burst GRB 111209A was found to be associated with a very luminous supernovae (SNe) SN 2011kl. The physics of GRB 111209A/SN 2011kl has been extensively studied in the literures, but does not settle down yet. By investigating in detail the characteristics of the X-ray light curve of GRB 111209A, coupled with the temporal and spectral features observed in SN 2011kl, we argue that a short-living supramassive magnetar can be responsible for the initial shallow X-ray emission. Then the electromagnetic extraction of spin energy from a black hole results in the steeply d…
We present and discuss the optical spectro-photometric observations of the nearby (z=0.087) Type I superluminous supernova (SLSN I) SN 2017gci, whose peak K-corrected absolute magnitude reaches Mg=-21.5 mag. Its photometric and spectroscopic evolution includes features of both slow and of fast evolving SLSN I, thus favoring a continuum distribution between the two SLSN-I subclasses. In particular, similarly to other SLSNe I, the multi-band light curves of SN 2017gci show two rebrightenings at about 103 and 142 days after the maximum light. Interestingly, this broadly agrees with a broad emissi…
Of the 30 or so Galactic magnetars, about 8 are in supernova remnants (SNRs). One of the most extreme magnetars, 1E 1841-045, is at the center of the SNR Kes 73 (G27.4+0.0), whose age is uncertain. We measure its expansion using three Chandra observations over 15 yr, obtaining a mean rate of 0.023% +/- 0.002% per yr. For a distance of 8.5 kpc, we obtain a shell velocity of 1100 km/s and infer a blast-wave speed of 1400 km/s. For Sedov expansion into a uniform medium, this gives an age of 1800 yr. Derived emission measures imply an ambient density of about 2 cm$^{-3}$ and an upper limit on the …
The light curves of some luminous supernovae are suspected to be powered by the spindown energy of a rapidly rotating magnetar. Here we describe a possible signature of the central engine: a burst of shock breakout emission occurring several days after the supernova explosion. The energy input from the magnetar inflates a high-pressure bubble that drives a shock through the pre-exploded supernova ejecta. If the magnetar is powerful enough, that shock will near the ejecta surface and become radiative. At the time of shock breakout, the ejecta will have expanded to a large radius (~10^{14} cm) s…
Fast-spinning strongly magnetized newborn neutron stars, including nascent magnetars, are popularly implemented as the engine of luminous stellar explosions. Here, we consider the scenario that they power various stripped-envelope supernovae, not only super-luminous supernovae Ic but also broad-line supernovae Ibc and possibly some ordinary supernovae Ibc. This scenario is also motivated by the hypothesis that Galactic magnetars largely originate from fast-spinning neutron stars as remnants of stripped-envelope supernovae. By consistently modeling the energy injection from magnetized wind and …
Unveiling the nature of SN 2022jli: The first double-peaked stripped-envelope supernova showing periodic undulations and dust emission at late times
Gemini Observatory, NSF’s National Optical-Infrared Astronomy Research Laboratory（吉米尼天文台，美国国家光学红外天文研究实验室）；Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales（迭戈·波塔莱斯大学工程与科学学院天体物理研究所）；Centro de Astronomía (CITEVA), Universidad de Antofagasta（安托法加斯塔大学天文学中心）；Las Campanas Observatory, Carnegie Observatories（卡内基观测台拉斯坎帕纳斯天文台）；Department of Physics and Astronomy, Aarhus University（奥胡斯大学物理与天文学系）；Fundación Chilena de Astronomía（智利天文学基金会）；Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas（西班牙高等科学研究中心基础物理研究所）；Institut de Ciències del Cosmos (UB-IEEC)（宇宙科学研究所）；Millennium Institute of Astrophysics MAS（天体物理学千年研究所）；European Southern Observatory（欧洲南方天文台）
SN 2022jli是首个双峰剥离包层超新星，表现出周期性波动和尘埃发射，研究其二次峰值可能由磁星驱动，揭示SE超亮超新星的物理机制。
The favored progenitor model for Gamma-ray Bursts (GRBs) with Supernova (SN) association is the core collapse of massive stars. One possible outcome of such a collapse is a rapidly spinning, strongly magnetized neutron star ("magnetar"). We systematically analyze the multi-wavelength data of GRB/SN associations detected by several instruments before 2017 June. Twenty GRB/SN systems have been confirmed via direct spectroscopic evidence or a clear light curve bump, as well as some spectroscopic evidence resembling a GRB-SN. We derive/collect the basic physical parameters of the GRBs and the SNe,…
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…
In this paper, we present the study for the energy reservoir powering the light curves (LCs) of PS1-12cil and SN 2012aa which are superluminous and luminous supernovae (SNe), respectively. The multi-band and bolometric LCs of these two SNe show unusual secondary bumps after the main peaks. The two-peaked LCs cannot be explained by any simple energy-source models (e.g., the $^{56}$Ni cascade decay model, the magnetar spin-down model, and the ejecta-circumstellar medium interaction model). Therefore, we employ the $^{56}$Ni plus ejecta-circumstellar medium (CSM) interaction (CSI) model, the magn…
We present the photometric and spectroscopic studies of a Type Ib SN 2015ap and a Type Ic SN 2016P. SN 2015ap is one of the bright (M$_{V}$ = $-$18.04 mag) Type Ib while SN 2016P lies at an average value among the Type Ic SNe (M$_{V}$ = $-$17.53 mag). Bolometric light curve modelling of SNe 2015ap and 2016P indicates that both the SNe are powered by $^{56}$Ni + magnetar model with $^{56}$Ni masses of 0.01 M$_{\odot}$ and 0.002 M$_{\odot}$, ejecta masses of 3.75 M$_{\odot}$ and 4.66 M$_{\odot}$, spin period P$_{0}$ of 25.8 ms and 36.5 ms and magnetic field B$_{p}$ of 28.39 $\times$ 10$^{14}$ Ga…
We perform a systematic study of the $^{56}$Ni mass ($M_{\rm Ni}$) of 27 stripped envelope supernovae (SESNe) by modeling their light-curve tails, highlighting that use of ``Arnett's rule'' overestimates $M_{\rm Ni}$ for SESN by a factor of $\sim$2. Recently, \citet{Khatami2019} presented a new model relating the peak time ($t_{\rm p}$) and luminosity ($L_{\rm p}$) of a radioactive-powered SN to its $M_{\rm Ni}$ that addresses several limitations of Arnett-like models, but depends on a dimensionless parameter, $β$. Using observed $t_{\rm p}$, $L_{\rm p}$, and tail-measured $M_{\rm Ni}$ values …
Magnetar power is believed to be at the origin of numerous super-luminous supernovae (SNe) of Type Ic, arising from compact, hydrogen-deficient, Wolf-Rayet type stars. Here, we investigate the properties that magnetar power would have on standard-energy SNe associated with 15-20Msun blue or red supergiant (BSG/RSG) stars. We use a combination of Eulerian grey radiation-hydrodynamics and non-LTE steady-state radiative transfer to study their dynamical, photometric, and spectroscopic properties. Adopting magnetar fields of 1, 3.5, 7 x 10^14G and rotational energies of 0.4, 1, and 3 x 10^51erg, w…
iPTF15dtg is a Type Ic supernova (SN) showing a broad light curve around maximum light, consistent with massive ejecta if we assume a radioactive-powering scenario. We study the late-time light curve of iPTF15dtg, which turned out to be extraordinarily luminous for a stripped-envelope (SE) SN. We compare the observed light curves to those of other SE SNe and also with models for the $^{56}$Co decay. We analyze and compare the spectra to nebular spectra of other SE SNe. We build a bolometric light curve and fit it with different models, including powering by radioactivity, magnetar powering, as…
GRB 111209A, one of the longest Gamma-Ray Bursts (GRBs) ever observed, is linked to SN 2011kl, the most luminous GRB-Supernova (SN) detected so far, which shows evidence for being powered by a magnetar central engine. We place SN 2011kl into the context of large samples of SNe, addressing in more detail the question of whether it could be radioactively powered, and whether it represents an extreme version of a GRB-SN or an underluminous Superluminous SN (SLSN). We model SN 2011kl using SN 1998bw as a template and derive a bolometric light curve including near-infrared data. We compare the prop…
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…
Two plateaus and one following bump in the X-ray light curve of GRB 170714A have been detected by the \textit{Swift}/X-Ray Telescope, which could be very meaningful for the central engine of gamma-ray bursts (GRBs), implying that the origin of this burst might be different from that of other ultra-long GRBs. We propose that merging two neutron stars into a hyper-massive quark star (QS) and then collapsing into a black hole (BH), with a delay time around $10^4$~s, could be responsible for those X-ray components. The hyper-massive QS is initially in a fluid state, being turbulent and differentia…
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…
SN 2021lwz: Another Exotic Luminous and Fast Evolving Optical Stripped Envelope Supernova ?
Instituto de Astrofísica de Canarias（加那利天体物理学研究所）；Universidad de La Laguna（拉古纳大学）；Konkoly Observatory, CSFK（孔科利天文台，匈牙利科学院研究网络）；Department of Optics & Quantum Electronics, University of Szeged（塞格德大学光学与量子电子学系）；ELTE Eötvös Loránd University, Gothard Astrophysical Observatory（厄特沃什·洛兰大学戈塔德天体物理观测站）；Graduate Institute of Astronomy, National Central University（国立中央大学天文学研究所）；GRANTECAN（格兰特卡南望远镜）；The Oskar Klein Centre, Department of Astronomy, Stockholm University（斯德哥尔摩大学奥斯特云中心天文学系）；Institute of Astronomy, University of Cambridge（剑桥大学天文学研究所）；Department of Astronomy, University of California, Berkeley（加州大学伯克利分校天文学系）
Type Ibn supernovae (SNe Ibn) are thought to be the core-collapse explosions of massive stars whose ejecta interact with He-rich circumstellar material (CSM). We report the discovery of a SN Ibn, with the longest rise-time ever observed, OGLE-2014-SN-131. We discuss the potential powering mechanisms and the progenitor nature of this peculiar stripped-envelope (SE), circumstellar-interacting SN. Optical photometry and spectroscopy were obtained with multiple telescopes including VLT, NTT, and GROND. We compare light curves and spectra with those of other known SNe Ibn and Ibc. CSM velocities ar…
We present a radio light curve of supernova (SN) 2014C taken with the Arcminute Microkelvin Imager (AMI) Large Array at 15.7 GHz. Optical observations presented by Milisavljevic et al. demonstrated that SN 2014C metamorphosed from a stripped-envelope Type Ib SN into a strongly interacting Type IIn SN within 1 year. The AMI light curve clearly shows two distinct radio peaks, the second being a factor of 4 times more luminous than the first peak. This double bump morphology indicates two distinct phases of mass-loss from the progenitor star with the transition between density regimes occurring a…
The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) is widely believed to be associated with the later activation of central engine. Some models of energy injection involve with a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving with a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time $\sim t_{\rm fb}$. Thus we propose a delayed energy injection model, the delayed energy would cause a notable rise to the Lorentz fact…
Prompt and Afterglow Constraints on the Central Engine of GRB 240825A
State Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理国家重点实验室）；University of Chinese Academy of Sciences, Chinese Academy of Sciences（中国科学院大学）；ICRANet（国际相对论天体物理中心网络）；ICRA, Dip. di Fisica, Sapienza Università di Roma（罗马大学物理系ICRA小组）；Università di Camerino（卡梅里诺大学）；Al-Farabi Kazakh National University（阿里-法拉比哈萨克国立大学）
本研究通过分析 GRB 240825A 的瞬时辐射三成分光谱、X 射线余辉衰减及 6.37 Hz 准周期振荡，对比磁星与黑洞两种中心引擎模型，发现六极磁星自转减慢模型能定量解释余辉，且磁星内部动力学可解释 QPO，综合观测支持长寿命磁星作为中心引擎。
At redshift z=0.03, the recently-discovered SN 2017egm is the nearest Type I superluminous supernova (SLSN) to date, and first near the center of a massive spiral galaxy (NGC 3191). Using SDSS spectra of NGC 3191, we find a metallicity ~2 Z$_\odot$ at the nucleus and ~1.3 Z$_\odot$ for a star forming region at a radial offset similar to SN 2017egm. Archival radio-to-UV photometry reveals a star-formation rate ~15 M$_\odot$ yr$^{-1}$ (with ~70% dust-obscured), which can account for a Swift X-ray detection, and stellar mass ~$10^{10.7}$ M$_\odot$. We model the early UV-optical light curves with …
Wide-field surveys are discovering a growing number of rare transients whose physical origin is not yet well understood. Here, we present optical and UV data and analysis of iPTF16asu, a luminous, rapidly-evolving, high velocity, stripped-envelope supernova. With a rest-frame rise-time of just 4 days and a peak absolute magnitude of $M_{\rm g}=-20.4$ mag, the light curve of iPTF16asu is faster and more luminous than previous rapid transients. The spectra of iPTF16asu show a featureless, blue continuum near peak that develops into a Type Ic-BL spectrum on the decline. We show that while the lat…
We present DES14X3taz, a new hydrogen-poor super luminous supernova (SLSN-I) discovered by the Dark Energy Survey (DES) supernova program, with additional photometric data provided by the Survey Using DECam for Superluminous Supernovae (SUDSS). Spectra obtained using OSIRIS on the Gran Telescopio CANARIAS (GTC) show DES14X3taz is a SLSN-I at z=0.608. Multi-color photometry reveals a double-peaked light curve: a blue and relatively bright initial peak that fades rapidly prior to the slower rise of the main light curve. Our multi-color photometry allows us, for the first time, to show that the i…
