Several explosions of thermonuclear supernovae (SNe Ia) have been found to exhibit deviations from spherical symmetry upon closer inspection. Examples are the gamma-ray lines from SN 2014J as measured by INTEGRAL/SPI, and morphology information from radioactive isotopes in older remnants such as Tycho. A systematic study on the effects of parameters such as ignition geometry and burning morphology in SNe Ia is still missing. We use a 2D hydrodynamics code with post-processing nucleosynthesis and simulate the double detonations in a sub-Chandrasekhar mass carbon-oxygen white dwarf starting from the nuclear runaway in the accumulated He envelope towards disruption of the white dwarf. We explore potential variety through four triggering scenarios that sample main asymmetry drivers. We further investigate their global effects on the aspherical structure of the ejecta based on individual elements. We apply the results to the well observed SN 2014J and other recently observed SN remnants in order to illustrate how these new observational data together with other observed quantities help to constrain the explosion and the progenitors of SNe Ia.
Early light from core-collapse supernovae, now detectable in high-cadence surveys, holds clues to a star and its environment just before it explodes. However, effects that alter the early light have not been fully explored. We highlight the possibility of non-radial flows at the time of shock breakout. These develop in sufficiently non-spherical explosions if the progenitor is not too diffuse. When they do develop, non-radial flows limit ejecta speeds and cause ejecta-ejecta collisions. We explore these phenomena and their observational implications, using global, axisymmetric, non-relativisti…
We investigate explosive nucleosynthesis in a non-rotating 15$M_\odot$ star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with the mass number $\le 70$ employing a large…
The merger of two neutron stars (NSs) or a neutron star and a black hole (BH) produces a radioactively-powered transient known as a kilonova, first observed accompanying the gravitational wave event GW170817. While kilonovae are frequently modeled in spherical symmetry, the dynamical ejecta and disk outflows can be considerably asymmetric. We use Monte Carlo radiative transfer calculations to study the light curves of kilonovae with globally axisymmetric geometries (e.g. an ellipsoid and a torus). We find that the variation in luminosity in these models is most pronounced at early times, and d…
We perform three-dimensional hydrodynamic simulations of aspherical core-collapse supernovae focusing on the matter mixing in SN 1987A. The impacts of four progenitor (pre-supernova) models and parameterized aspherical explosions are investigated. The four pre-supernova models include a blue supergiant (BSG) model based on a slow merger scenario developed recently for the progenitor of SN 1987A (Urushibata et al. 2018). The others are a BSG model based on a single star evolution and two red supergiant (RSG) models. Among the investigated explosion (simulation) models, a model with the binary m…
Massive stars are characterized by a significant loss of mass either via spherically symmetric stellar winds or pre-explosion pulses, or by aspherical forms of circumstellar matter (CSM) such as bipolar lobes or outflowing circumstellar equatorial disks. A significant fraction of most massive stars end their lives by a core collapse; supernovae (SNe) are always located inside circumstellar envelopes created by their progenitors. We study the dynamics and thermal effects of collision between expanding ejecta of SNe and CSM that may be formed during, for example, a sgB[e] star phase, a luminous …
Shock breakout is the earliest, readily-observable emission from a core-collapse supernova explosion. Observing supernova shock breakout may yield information about the nature of the supernova shock prior to exiting the progenitor and, in turn, about the core-collapse supernova mechanism itself. X-ray Outburst 080109, later associated with SN 2008D, is a very well-observed example of shock breakout from a core-collapse supernova. Despite excellent observational coverage and detailed modeling, fundamental information about the shock breakout, such as the radius of breakout and driver of the lig…
The geometric structure of supernova remnants (SNR) provides a clue to unveiling the pre-explosion evolution of their progenitors. Here we present an X-ray study of N103B (0509-68.7), a Type Ia SNR in the Large Magellanic Cloud, that is known to be interacting with dense circumstellar matter (CSM). Applying our novel method for feature extraction to deep Chandra observations, we have successfully resolved the CSM, Fe-rich ejecta, and intermediate-mass element (IME) ejecta components, and revealed each of their spatial distribution. Remarkably, the IME ejecta component exhibits a double-ring st…
It is believed that the relativistic jets of gamma-ray bursts (GRBs) should initially propagate through a heavy envelope of the massive progenitor stars or through a merger ejecta formed from the compact binary mergers. The interaction of a jet with a stellar envelope or a merger ejecta can lead to the deceleration of the head material of the jet and simultaneously the formation of a hot cocoon. However, this jet-envelope/ejecta interaction is actually undetectable with electromagnetic radiation and can only be inferred indirectly by the structure of the breakout jet. Therefore, as a solution …
This paper presents a detailed analysis of supernova remnant (SNR) N103B located in the Large Magellanic Cloud (LMC), based on Suzaku and Chandra observations. The spectrum of the entire SNR was reproduced using 3 ISM components with the kT of 0.32, 0.56, and 0.92keV and one ejecta component of 3.96keV, based on spectral analysis of the Suzaku/XIS data. The ejecta was overabundant in heavy elements, such as Mg, Si, S, Ca, Fe, and Ni. The unprecedentedly high quality of data obtained by XIS, allowed us to correctly distinguish between the emissions from the ISM and the ejecta for the first time…
It was recently shown that the bolometric light curves of type II supernovae (SNe) allow an accurate and robust measurement of the product of the radiation energy in the ejecta, $E_r$, and the time since the explosion, $t$, at early phases ($t\lesssim 10d$) of the homologous expansion. This observable, denoted here $ET \equiv E_rt$ is constant during that time and depends only on the progenitor structure and explosion energy. We use a 1D hydrodynamic code to find $ET$ of simulated explosions of 145 red supergiant progenitors obtained using the stellar evolution code MESA, and relate this obser…
We present visible-light and ultraviolet (UV) observations of the supernova PTF12glz. The SN was discovered and monitored in near-UV and R bands as part of a joint GALEX and Palomar Transient Factory campaign. It is among the most energetic Type IIn supernovae observed to date (~10^{51} erg). If the radiated energy mainly came from the thermalization of the shock kinetic energy, we show that PTF12glz was surrounded by ~1 solar mass of circumstellar material (CSM) prior to its explosive death. PTF12glz shows a puzzling peculiarity: at early times, while the freely expanding ejecta are presumabl…
The astrophysical production site of the heaviest elements in the universe remains a mystery. Incorporating heavy element signatures of metal-poor, $r$-process enhanced stars into theoretical studies of $r$-process production can offer crucial constraints on the origin of heavy elements. In this study, we introduce and apply the "Actinide-Dilution with Matching" model to a variety of stellar groups ranging from actinide-deficient to actinide-enhanced to empirically characterize $r$-process ejecta mass as a function of electron fraction. We find that actinide-boost stars do not indicate the nee…
Since the discovery of FRB 200428 associated with the Galactic SGR 1935+2154, magnetars are considered to power fast radio bursts (FRBs). It is widely believed that magnetars could form by core-collapse (CC) explosions and compact binary mergers, such as binary neutron star (BNS), binary white dwarfs (BWD), and neutron star-white dwarf (NSWD) mergers. Therefore, it is important to distinguish the various progenitors. The expansion of the merger ejecta produces a time-evolving dispersion measure (DM) and rotation measure (RM) that can probe the local environments of FRBs. In this paper, we deri…
We present our spectropolarimetric observations of SN 2017egm, a Type I superluminous supernova (SLSN-I) in a nearby galaxy NGC 3191, with Subaru telescope at 185.0 days after the g-band maximum light. This is the first spectropolarimetric observation for SLSNe at late phases. We find that the degree of the polarization in the late phase significantly changes from that measured at the earlier phase. The spectrum at the late phase shows a strong Ca emission line and therefore we reliably estimate the interstellar polarization component assuming that the emission line is intrinsically unpolarize…
We perform a series of two-dimensional radiation-hydrodynamic simulations of the collision between supernova ejecta and circumstellar media (CSM). The hydrodynamic interaction of a fast flow and the surrounding media efficiently dissipates the kinetic energy of the fast flow and considered as a dominant energy source for a specific class of core-collapse supernovae. Despite some observational evidence for aspherical ejecta and/or CSM structure, multi-dimensional effects in the ejecta-CSM interaction are relatively unexplored. Our numerical simulations equipped with an adaptive mesh refinement …
We investigate the possible effects of the supernova ejecta hitting the companion star in iPTF 13bvn, focusing on the observable features when it becomes visible. iPTF 13bvn is a type Ib supernova that may become the first case that its progenitor is identified as a binary by near future observations. According to calculations by Bersten et al. (2014), the progenitor should have a mass $\approx3.5M_\odot$ to reproduce the supernova light curve, and such compact stars could only be produced via binary evolution. This is one of the reasons that we expect the progenitor to be a binary, but it sho…
The physical process whereby a carbon--oxygen white dwarf explodes as a Type Ia supernova (SN Ia) remains highly uncertain. The degree of neutronization in SN Ia ejecta holds clues to this process because it depends on the mass and the metallicity of the stellar progenitor, and on the thermodynamic history prior to the explosion. We report on a new method to determine ejecta neutronization using Ca and S lines in the X-ray spectra of Type Ia supernova remnants (SNRs). Applying this method to \textit{Suzaku} data of Tycho, Kepler, 3C 397 and G337.2$-$0.7 in the Milky Way, and N103B in the Large…
Supernova remnants (SNRs) that contain pulsar wind nebulae (PWNe) are characterized by distinct evolutionary stages. In very young systems, the PWN drives a shock into the innermost supernova (SN) material, giving rise to low-excitation lines and an infrared (IR) continuum from heated dust grains. These observational signatures make it possible to cleanly measure the properties of the deepest SN ejecta layers that can, in turn, provide constraints on the SN progenitor. We present Herschel Space Observatory far-IR observations of the PWN in the Galactic SNR Kes 75, containing the youngest known…
The origin of the diverse light-curve shapes of Type II supernovae (SNe), and whether they come from similar or distinct progenitors, has been actively discussed for decades. Here we report spectropolarimetry of two fast declining Type II (Type IIL) SNe: SN 2013ej and SN 2017ahn. SN 2013ej exhibited high continuum polarization from very soon after the explosion to the radioactive tail phase with time-variable polarization angles. The origin of this polarimetric behavior can be interpreted as the combination of two different aspherical structures, namely an aspherical interaction of the SN ejec…
The remnants of core-collapse supernovae (SNe) have complex morphologies that may reflect asymmetries and structures developed during the progenitor SN explosion. Here we investigate how the morphology of the SNR Cassiopeia A (Cas A) reflects the characteristics of the progenitor SN with the aim to derive the energies and masses of the post-explosion anisotropies responsible for the observed spatial distribution of Fe and Si/S. We model the evolution of Cas A from the immediate aftermath of the progenitor SN to the three-dimensional interaction of the remnant with the surrounding medium. The p…
Core-collapse supernovae (CCSNe) are the explosions of massive stars following the collapse of the stars' iron cores. Poznanski (2013) has recently suggested an observational correlation between the ejecta velocities and the inferred masses of the red supergiant progenitors of type II-P explosions, which implies that the kinetic energy of the ejecta ($E_{\textrm{kin}}$) increases with the mass of the progenitor. I point out that the same conclusion can be reached from the model-free observed correlation between the ejected $^{56}$Ni masses ($M_{\textrm{Ni}}$) and the luminosities of the progen…
The Vela supernova remnant (SNR) shows several ejecta fragments protruding beyond the forward shock (shrapnel). Recent studies have revealed high Si abundance in two shrapnel (A and G), located in opposite directions with respect to the SNR center. This suggests the possible existence of a Si-rich jet-counterjet structure. We analyzed an XMM-Newton observation of a bright clump, behind shrapnel G, which lies along the direction connecting A and G. The aim is to study the physical and chemical properties of this clump to ascertain whether it is part of this putative jet-like structure. We produ…
The progenitors of SNe Ia are not yet fully understood. The two leading progenitor scenarios are the single-degenerate (SD) scenario and the double-degenerate scenario. In the SD scenario, the collision of the SN Ia ejecta with its companion star is expected to produce detectable ultraviolet (UV) emission in the first few days after the SN explosion within certain viewing angles. A strong UV flash has recently been detected in an SN 2002es-like peculiar SN Ia iPTF14atg by Cao et al., which is interpreted as evidence of an early-time UV signature due to SN ejecta interacting with its companion …
Multi-dimensional simulations of advanced nuclear burning stages of massive stars suggest that the Si/O layers of presupernova stars harbor large deviations from the spherical symmetry typically assumed for presupernova stellar structure. We carry out three-dimensional core-collapse supernova simulations with and without aspherical velocity perturbations to assess their potential impact on the supernova hydrodynamics in the stalled shock phase. Our results show that realistic perturbations can qualitatively alter the postbounce evolution, triggering an explosion in a model that fails to explod…
We investigate the effect of the circumstellar medium density profile on the X-ray emission from outer ejecta knots in the Cassiopeia A supernova remnant using the 1 Ms Chandra observation. The spectra of a number of radial series of ejecta knots at various positions around the remnant are analyzed using techniques similar to those devised in previous papers. We can obtain a reasonable match to our data for a circumstellar density profile proportional to r^-2 as would arise from the steady dense wind of a red supergiant, but the agreement is improved if we introduce a small (0.2-0.3 pc) centra…
Matter mixing is one important topic in the study of core-collapse supernova (CCSN) explosions. In this paper, we perform two-dimensional hydrodynamic simulations to reproduce the high velocity $^{56}$Ni clumps observed in SN 1987A. This is the first time that large density perturbation is proposed in the CCSN progenitor to generate Rayleigh-Taylor (RT) instability and make the effective matter mixing. In the case of a spherical explosion, RT instability is efficient at both C+O/He and He/H interfaces of the SN progenitor. Radial coherent structures shown in perturbation patterns are important…
We analyze three Chandra observations, with a combined exposure time of 99 ks, of the Galactic supernova remnant RCW 103, a young supernova remnant, previously with no clear detection of metal-rich ejecta. Based on our imaging and spectral analyses of these deep Chandra data, we find evidence for metal-rich ejecta emission scattered throughout the remnant. X-ray emission from the shocked ejecta is generally weak, and the shocked circumstellar medium (CSM) is a largely dominant component across the entire remnant. The CSM component shows abundances of ~0.5 solar, while Ne, Mg, Si, S, and Fe abu…
We present a comprehensive X-ray spectroscopy and imaging study of supernova remnant W49B using archival XMM-Newton observations. The overionization state of the shocked ejecta in W49B is clearly indicated by the radiative recombination continua of Si XIV, S XV, and Fe XXV, combined with the Ly$α$ lines of Ca and Fe. The line flux images of W49B indicate high emission measures of the central bar-like region for almost all the emission lines, while the equivalent width maps reveal a stratified structure for the metal abundance distributions. The global spectrum of W49B is well reproduced by a m…
The breakout of a supernova shock wave through the progenitor star's outer envelope is expected to appear as an X-ray flash. However, if the supernova explodes inside an optically-thick wind, the breakout flash is delayed. We present a simple model for estimating the conditions at shock breakout in a wind based on the general observable quantities in the X-ray flash lightcurve: the total energy E_X, and the diffusion time after the peak, t_diff. We base the derivation on the self-similar solution for the forward-reverse shock structure expected for an ejecta plowing through a pre-existing wind…
Some supernova (SN) explosions show evidence for interaction with pre-existing non-spherically symmetric circumstellar medium (CSM) in their light curves, spectral line profiles, and polarization signatures. To better understand the connection with binary stars and to aid in the interpretation of observations, we perform two-dimensional axisymmetric hydrodynamic simulations where an expanding spherical SN ejecta initialized with realistic density and velocity profiles collide with various aspherical CSM distributions. We consider CSM in the form of a circumstellar disk, colliding wind shells i…
The recent discovery that the Fe-K line luminosities and energy centroids observed in nearby SNRs are a strong discriminant of both progenitor type and circumstellar environment has implications for our understanding of supernova progenitor evolution. Using models for the chemical composition of core-collapse supernova ejecta, we model the dynamics and thermal X-ray emission from shocked ejecta and circumstellar material, modeled as an $r^{-2}$ wind, to ages of 3000 years. We compare the X-ray spectra expected from these models to observations made with the Suzaku satellite. We also model the …
Supernova remnants (SNRs) are diffuse extended sources characterized by a complex morphology and a non-uniform distribution of ejecta. Such a morphology reflects pristine structures and features of the progenitor supernova (SN) and the early interaction of the SN blast wave with the inhomogeneous circumstellar medium (CSM). Deciphering the observations of SNRs might open the possibility to investigate the physical properties of both the interacting ejecta and the shocked CSM. This requires accurate numerical models which describe the evolution from the SN explosion to the remnant development a…
Spherical and aspherical models are presented for two outbursts in 2012 of supernova 2009ip. Models are based on a scenario which suggests that the August 2012 outburst is caused by the explosive shell ejection from LBV-presupernova. The model predicts an emergence of an unobserved outburst in late July 2012 related to a shock breakout and a subsequent diffusive radiative cooling of the ejected envelope. The luminosity of the first observed outburst in August 2012 was presumably powered by the central source, whereas the second, more powerful outburst in late September 2012, was caused by the …
Recently, a hydrogen-poor superluminous supernova (SLSN) iPTF15esb at redshift $z=0.224$ was reported, whose light curve (LC) and spectrum show several unusual characteristics. Its late-time spectrum shows a strong, broad H$α$ emission line and the bolometric LC exhibits two peaks and a post-peak plateau. Here we propose an ejecta-circumstellar medium (CSM) interaction model involving multiple shells and winds to explain this double-peak SN. We find that the theoretical LC reproduced by this model can well match the observations of iPTF15esb. Based on this result, we infer that the progenitor …
We investigate the impact of asymmetric neutrino-emissions on explosive nucleosynthesis in core-collapse supernovae (CCSNe) of progenitors with a mass range of 9.5 to 25$M_{\odot}$. We perform axisymmetric, hydrodynamic simulations of the CCSN explosion with a simplified neutrino-transport, in which anti-correlated dipolar emissions of $ν_{\rm e}$ and ${\bar ν}_{\rm e}$ are imposed. We then evaluate abundances and masses of the CCSN ejecta in a post-processing manner. We find that the asymmetric $ν$-emission leads to the abundant ejection of $p$- and $n$-rich matter in the high-$ν_{\rm e}$ and…
(Abridged) We aim at linking the dynamical and radiative properties of the remnant of SN 1987A to the geometrical and physical characteristics of the parent aspherical SN explosion and to the internal structure of its progenitor star. We performed 3D hydrodynamic simulations which describe the long-term evolution of SN 1987A from the onset of the SN to the full-fledged remnant at the age of 50 years, accounting for the pre-SN structure of the progenitor star. The simulations include all physical processes relevant for the complex phases of SN evolution and for the interaction of the SNR with t…
In the single degenerate (SD) scenario of type Ia supernovae (SNe Ia), the collision of the ejecta with its companion results in stripping hydrogen rich matter from the companion star. This hydrogen rich matter might leave its trace in the light curves and/or spectra. In this paper, we perform radiation hydrodynamical simulations of this collision for three binary systems. As a result, we find that the emission from the shock-heated region is not as strong as in the previous study. This weak emission, however, may be a result of our underestimate of the coupling between the gas and radiation i…
The power of binaries on stripped-envelope supernovae across metallicity: uniform progenitor parameter space and persistently low ejecta masses, but subtype diversity
Supernova remnants (SNRs) retain crucial information about both their parent explosion and circumstellar material left behind by their progenitor. However, the complexity of the interaction between supernova ejecta and ambient medium often blurs this information, and it is not uncommon for the basic progenitor type (Ia or core-collapse) of well-studied remnants to remain uncertain. Here we present a powerful new observational diagnostic to discriminate between progenitor types and constrain the ambient medium density of SNRs solely using Fe K-shell X-ray emission. We analyze all extant Suzaku …
The remnants of Type Ia supernovae can provide important clues about their progenitor-histories. We discuss two well-observed supernova remnants (SNRs) that are believed to result from a Type Ia SN and use various tools to shed light on the possible progenitor history. We find that Kepler's SNR is consistent with a symbiotic binary progenitor consisted of a white dwarf and an AGB star. Our hydrosimulations can reproduce the observed kinematic and morphological properties. For Tycho's remnant we use the characteristics of the X-ray spectrum and the kinematics to show that the ejecta has likely …
The aim of this work is to bridge the gap between CC SNe and their remnants by investigating how post-explosion anisotropies in the ejecta influence the structure and chemical properties of the remnant at later times. We performed three-dimensional magneto-hydrodynamical simulations starting soon after the SN event and following the evolution of the system in the circumstellar medium (consisting of the wind of the stellar progenitor), for 5000 years, obtaining the physical scenario of a SNR. Here we focused the analysis on the case of a progenitor red supergiant of 19.8 M_sun. We also investig…
One of the key observables for determining the progenitor nature of Type Ia supernovae is provided by their immediate circumstellar medium, which according to several models should be shaped by the progenitor binary system. So far, X-ray and radio observations indicate that the surroundings are very tenuous, producing severe upper-limits on the mass loss from winds of the progenitors. In this study, we perform numerical hydro-dynamical simulations of the interaction of the SN ejecta with circumstellar structures formed by possible mass outflows from the progenitor systems and we estimate numer…
We present neutrino-transport hydrodynamic simulations of electron-capture supernovae (ECSNe) in \texttt{FLASH} with new two-dimensional (2D) collapsing progenitor models. These progenitor models feature the 2D modelling of oxygen-flame propagation until the onset of core collapse. We perform axisymmetric simulations with 6 progenitor models that, at the time of collapse, span a range of propagating flame front radii. For comparison, we also perform a simulation with the same setup using the canonical, spherically-symmetrical progenitor model n8.8. We found that the variations in the progenito…
We report the early discovery and multi-color ($BVI$) high-cadence light curve analyses of a rapidly-declining sub-Chandrasekhar Type Ia supernova KSP-OT-201509b (= AT2015cx) from the KMTNet Supernova Program. The Phillips parameter and color stretch parameter of KSP-OT-201509b (= AT2015cx) are $Δ$$M_{B,15}$ $\simeq$ 1.62 mag and $s_{BV}$ $\simeq$ 0.54, respectively, at an inferred redshift of 0.072. These, together with other measured parameters (such as the strength of the secondary $I$-band peak, colors and luminosity), identify the source to be a rapidly-declining Type Ia of transitional n…
We present extensive optical observations of the normal Type Ic supernova (SN) 2007gr, spanning from about one week before maximum light to more than one year thereafter. The optical light and color curves of SN 2007gr are very similar to those of the broad-lined Type Ic SN 2002ap, but the spectra show remarkable differences. The optical spectra of SN 2007gr are characterized by unusually narrow lines, prominent carbon lines, and slow evolution of the line velocity after maximum light. The earliest spectrum (taken at t=-8 days) shows a possible signature of helium (He~I 5876 at a velocity of ~…
The bright long-lived Type II SN 2021irp powered by aspherical circumstellar material interaction (II): Estimating the CSM mass and geometry with polarimetry and light curve modeling
PS15dpn is a luminous rapidly rising Type Ibn supernova (SN) discovered by Pan-STARRS1 (PS1). Previous study showed that its bolometric light curve (LC) cannot be explained by the $^{56}$Ni model. In this paper, we used the $^{56}$Ni model, the magnetar model, the circumstellar interaction (CSI) model, and the CSI plus $^{56}$Ni model to fit the bolometric LC of PS15dpn. We found that the $^{56}$Ni model can fit the bolometric LC but the parameters are unrealistic, and that the magnetar model, the CSI model, and the CSI plus $^{56}$Ni model can match the data with reasonable parameters. Consid…
I propose a scenario according to which the dense compact circumstellar matter (CSM) that the ejecta of many core collapse supernovae (CCSNe) collide with within several days after explosion results from a dense zone where in addition to the stellar wind there is gas that does not reach the escape velocity. In this effervescent zone around red supergiant (RSG) stars, there are dense clumps that are ejected from the vicinity of the RSG surface, rise to radii of tens of astronomical units, and then fall back. I consider two simple velocity distributions of the ejected clumps. I find that the den…
The Double-Peaked Calcium-Strong SN 2025coe: Progenitor Constraints from Early Interaction and Ejecta Asymmetries
University of California, Davis（加州大学戴维斯分校）；University of Virginia（弗吉尼亚大学）；National Radio Astronomy Observatory（国家射电天文台）；Stockholm University（斯德哥尔摩大学）；Center for Astrophysics | Harvard & Smithsonian（哈佛-史密森天体物理中心）
