Supernova Remnantsand their Progenitors
Presentation Abstracts
Welcome and Opening Remarks
Some rare elements (e.g., Ti, Cr, Mn, Ni) in supernova remnants hold information about their progenitors and the explosion itself. We expect that some of these elements can be observed by X-rays (in particular, using future X-ray calorimeters). We show our recent results of Cassiopeia A using the Chandra observations related to this topic. First, we introduce a first measurement of the Mn/Cr ratio in this remnant. This ratio could be an indicator of the initial metallicity of its progenitor star. Our result shows that the progenitor of Cassiopeia A supernova had a sub-solar initial metallicity, suggesting a binary progenitor for this remnant. Next, we report a first detection of Ti and Cr at the Fe-rich fingers in this remnant. The amount of these elements is sensitive to entropy during the explosion, which allows us to estimate this important physical parameter for the first time. We expect that the future observations of these rare elements will be a new tool to probe the supernova and stellar physics in the next decades.
The exact mechanism of the core-collapse supernovae (CCSNe) is disputed. The jittering jets explosion mechanism proposes that stochastic convective motion, amplified by instabilities, results in intermittent jets that explode the star. I show that for a wide range of masses, 1D simulations exhibit convective motion in the inner burning layers that when scaled to corresponding 3D simulations, are sufficient to supply the jittering jets explosion mechanism for CCSNe.
SNR 0540-69.3 is an O-rich SNR located in the LMC. I will present a 3D reconstruction of the ejecta based on observations with VLT/MUSE, which gives new insights into the explosion and progenitor. The observations reveal small clumpy rings in the innermost region, a larger ring of [O III] emission, as well as a high-velocity H-rich blob. A clump-finding algorithm was used to analyse the 3D geometry and to obtain an improved age estimate of ~1100 years. The detection of Balmer lines in the innermost ejecta confirms that SNR 0540 was a Type II supernova and that hydrogen was mixed down to low velocities in the explosion. These results highlight the importance of asymmetries in supernova explosions.
In this lightning talk I will quickly overview the difficulties behind 3D modelling of Nebular Phase Supernova and highlight some very first results when compared to their 1D model counterparts. The newly developed code takes some of the new, state-of-the-art 3D hydrodynamical supernova explosion models as basis to create the 3D nebular phase structure, which is then solved fully self-consistent for the optically thin nebula. This NLTE structure is then used to create a viewing-angle dependent spectrum.
It is well known that dust grains form in the ejecta of supernovae. However, due to interactions with the circumstellar and interstellar medium, reverse shocks will traverse the ejecta which could potentially destroy large amounts of the newly formed dust material by sputtering or grain-grain collisions. (Magneto-)hydrodynamic simulations help us to model the temporal evolution of gas density and temperature for the passage of a reverse shock in a clumpy supernova ejecta. Subsequently, dust trajectories and destruction rates can be computed using our dust post-processing code Paperboats, which includes gas drag, grain charging, sputtering, gas accretion, and grain-grain collisions. The oxygen-rich supernova remnant Cassiopeia A provides a unique laboratory to investigate the destruction of dust by the reverse shock. I will present destruction rates as a function of initial grain sizes, clump gas densities and magnetic fields for this unique system. The results show that grain-grain collisions and sputtering are synergistic and that grain-grain collisions can play a crucial role in determining the surviving dust budget in supernova remnants.
Although Type Ia supernovae (SNe Ia) are widely used as cosmic distance indicators, there is still debate about their progenitors and explosion properties. Specifically, late time light curves of SNe Ia remain poorly studied since SNe Ia are very faint at these phases. However, these late phases can be very informative as the SN ejecta has become fully transparent and we can see into the deepest layers of the ejecta, which may shed light on the explosion mechanism or mass of the exploding WD. We present from our investigation the recently discovered NIR plateau in Type Ia supernovae, which extends from 150 d to 500 d. The increased size of the sample of SNe Ia observed in the NIR at these phases allows us to confirm the presence of the plateau in H- and J-bands, whilst no plateau has been found in the K-band. We are able to relate this behaviour to specific spectral features and their evolution, and present comparisons with models of the nebular phase of SNe Ia.
Current analysis of SNe Ia are focused on maximum and post-maximum light. Although, photometric observations displays early features of light curves given the development of large surveys and the cadence that they provided. Spectroscopic observations are missing at those early phases. We can track the evolution of the ejecta throw spectra and compare it with observations at later epochs from the stratification of the elements. We aim to provide a spectroscopic early sample collected from the literature and our own observations within five days after explosion. In order to constrain theoretical spectroscopic models at early epochs and disentangle the nature of type Ia SNe from the spectroscopic point of view.
We present a systematic, global study of Galactic supernova remnants (SNRs) hosting central compact objects (CCOs), aimed at addressing their supernova progenitors and explosion properties. We performed a spatially resolved X-ray spectroscopy study using the Chandra and XMM-Newton telescopes with region selection chosen by an algorithm that chooses pixels based on similar surface brightness. The SNR’s regions were fit by a one- or two-component plasma shock models in order to separate the shocked ISM from the reverse shock-heated ejecta. In order to estimate the progenitor mass, we compared the fitted abundances to the explosion yields from five of the most used progenitor explosion models. We also explored degeneracies in the model fitting, particularly the effect of altering the explosion energy on the progenitor mass estimate. No explosion models match the ejecta yields for any of the SNRs in our sample. By comparing the fitted abundances to the most recent core-collapse nucleosynthesis models, we present our best estimates for the progenitor mass of each SNR and highlight discrepancies between the observed data and the theoretical explosion models.
We analyze and model the infra-red spectrum of the Cassiopeia A supernova remnant, with the aim of determining the masses of various elements in the unshocked ejecta. In this way we complement the survey of the X-ray emitting ejecta of Hwang & Laming (2012), to provide a complete census of the elemental composition of the Cas A ejecta. We calculate photoionization-recombination equilibria to determine the ionization balance of various elements in the ejecta as a function of density, using the X-ray and UV emission from the forward and reverse shocks as the ionizing source. With the assumption that all emission lines are principally excited at the ejecta density that maximizes their emission, we can convert observed line intensities into element masses, and find results that generally support the conclusions of Hwang & Laming (2012). The majority of the ~ 3 Msun ejecta have already been through the reverse shock are are seen today in X-rays. A minority ~ 0.5 Msun is still expanding inside the reverse shock and emits in the infra-red.
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The standard paradigm for normal core-collapse supernovae has converged on the convective engine. But the details of this convection remains poorly understood. This talk reviews the different probes of this convection, their strengths and their limitations. In particular, I will discuss the successes and exciting potential of supernova remnant observations to probe this standard paradigm of supernova engines.
We present 3D hydrodynamic simulations of neutrino-driven supernovae (SNe) with the PROMETHEUS -HOTB code, evolving the asymmetrically expanding ejecta from shock breakout until they reach the homologous expansion phase after roughly one year. We focus on the simulations of two red supergiant (RSG) and two blue supergiant (BSG) progenitors and discuss i) the growth of explosion asymmetries produced by hydrodynamic instabilities during the first second of the explosion, ii) their later fragmentation by Rayleigh-Taylor instabilities and iii) the late time acceleration and inflation of the ejecta caused by the radioactive decay of 56Ni to 56 Fe. The last effect, also known as ‘Ni-bubble expansion’, accelerates and causes an inflation of the initially overdense Ni-rich clumps, which evolve into underdense, extended fingers, enveloped by overdense skins of compressed surrounding matter.
Stellar mass loss is one of the crucial elements which determine the fate of progenitors of core-collapse supernovae (SNe). Through the formation of circumstellar medium (CSM), it can also have an influence on the subsequent evolution of the SN or supernova remnant (SNR). Despite its importance, the detailed models for stellar mass loss have not been incorporated with simulations of SNRs. As a first step, we investigate the evolution of an ultra-stripped supernova remnant (USSNR), an SNR hosting a double neutron star binary at its center. By accounting for the mass-loss history of the progenitor binary proposed by the previous simulations of stellar evolution, we construct the large-scale structure of the CSM, and compute the explosion and subsequent evolution of the SN surrounded by such a circumstellar environment. We find that the CSM encompasses an extended region characterized by a hot plasma, and the USSNR blast wave is drastically weakened while penetrating through this hot plasma. Radio continuum emission from a young USSNR is sufficiently bright to be detectable if it inhabits our galaxy but faint compared to the observed Galactic SNRs.
The next Galactic core-collapse supernova (CCSN) has long been lauded our best prospect for observing gravitational waves (GWs), neutrinos, and electromagnetic waves (EM) from a single astrophysical transient. While it is all but guaranteed that we will see neutrinos and EM (in at least some bands) from this event, the same sadly cannot be said for GWs. Despite horizon distance estimates gleaned from matched-filter signal-to-noise ratios suggesting otherwise, we are — at present — more likely to miss GWs from the next Galactic CCSN that detect them. In this talk, I will (1) outline why traditional horizon distance estimates are not appropriate for the CCSN case, (2) present an alternative figure of merit from which far more realistic estimates can be calculated, and (3) suggest ways in which the detection prospects for GWs from CCSNe can be improved in the near future.
Most of the modeling of core-collapse supernovae has been focused on the hundreds of milliseconds around the collapse of the iron core, the birth of the proto-neutron star and the launching of the supernova shockwave. While the physics that occurs in this narrow window is essential to the explosion, most of the observations of these supernovae come hours to weeks to years later as the shockwave lifts the envelope of the star and propels this ejecta into the interstellar medium. To compare our models to the full panoply of observations, and especially to fulfill the promise of multi-messenger astronomy, we need to build comprehensive models of core-collapse supernovae that stretch from the late days of stellar evolution through the explosion and onto the supernova and supernova remnant phases. I will present some preliminary steps toward this objective to illustrate the importance of spanning the entirety of each core-collapse supernova.
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Recent observations across the electromagnetic spectrum have revealed the eventful life of evolved massive stars approaching core collapse. Contrary to expectations, a large fraction of massive stars experience violent eruptions in the centuries leading up to stellar demise. The physical mechanism that regulates the mass ejections is debated, and current proposals include instabilities related to the last nuclear burning stages of the progenitor star. No matter what the physical cause is, the presence of large amount of material in the proximity of the progenitor leaves clear imprints on the appearance of the supernova explosion, as the explosion’s shock encounters a medium enriched by the previous mass-loss activity of the progenitor. In this talk, I will review the status of our understanding of mass loss in evolved massive stars that resulted from late-time X-ray and radio observations of stellar explosions.
The pulsar-driven supernova model, where the spin-down energy of a ~ms rotating highly magnetized neutron star powers the luminosity and/or dynamics of the supernova, can be used to explain a number of transients, most notably Type-I Super-Luminous Supernovae (SLSNe-I). In this model, the energy from the pulsar is injected into the ejecta through broadband emission from the pulsar wind nebula (PWN). There are several models which can explain SLSNe-I light curves, so quasi-thermal optical supernova emission can not differentiate between different models, but other signals, such as the optical spectrum at late times, can.
We have performed spectral synthesis simulations on pure oxygen ejecta with a central PWN to try and reproduce the observed spectra of SN2012au, which was observed at around 1 year and around 6 years post-explosion. We varied the ejecta mass, pulsar luminosity, and pulsar spectrum to find how these parameters affect the line luminosities, and find that while we can reproduce the spectrum at 6 years, the model is too simple and lacks some physics needed to reproduce the spectrum at 1 year.
We investigate the occurrence of rapid rotation induced Chemically Homogeneous Evolution (CHE) caused by strong tides and mass accretion in binary systems. Using MESA we derive a relation for the minimum initial angular frequency required by a single star to experience CHE and extended this to derive a similar relation for accretion induced CHE in binaries by generalising the analytical relation in Packet (1981) and here we present some implications. We conduct population study by evolving stars under the influence of strong tides in short-period binaries and accretion induced rapid rotation. We find accretion CHE (compared to tidal CHE) to be the dominant means of producing homogeneous stars. Unlike tidal CHE, we find that CH stars arising due to accretion can retain a larger fraction of their angular momentum till core-collapse. Thus we show that accretion CHE could be an important formation channel for electromagnetic transients like GRBs/Ic-BL (SLSN-I/Ic-BL) under the collapsar (magnetar) formalism and a single CH star could lead to both the transients under their respective formation scenario.
I will present a recent study of the SNR G292.0+1.8 that aims to constrain the properties of its progenitor star. Hydrodynamic modeling of the SNR evolution and its nucleosynthetic yields indicate that the progenitor was likely a relatively low mass star that experienced significant mass loss through a binary interaction and would have produced a stripped-envelope supernova explosion.
The vast majority of core-collapse are thought to produce a neutron star, whose rotational energy powers a pulsar wind nebula (PWN) which then expands inside the resultant supernova remnant (SNR). As a result, the evolution of this PWN is sensitive to the nature of the progenitor supernova and its environment. In this presentation, I will demonstrate how, by modeling the observed properties of a PWN with a model for its evolution inside a SNR, one can estimate the properties of progenitor supernova and star, and compare these results with those derived from independent methods.
Early-time characterization of supernova light curves is critical for probing the physical characteristics of the progenitor. Blind supernova searches using wide-field, high-cadence photometric surveys such as the Transiting Exoplanet Survey Satellite (TESS) can reveal shock breakout emission from core collapse or excess heating due to a stellar companion during a Type Ia supernova. We present a pipeline that can analyze and model time-series imaging data from the TESS full frames in order to characterize supernovae during the rise. The pipeline performs point-spread function (PSF) photometry on the full-frame images (FFIs) and incorporates auxiliary and complementary light curves collected in other passbands from the ground with the aim of constructing a robust model of the progenitor. Using selected high signal-to-noise supernova detections in the TESS data collected during the first four years of the mission, we illustrate the range of modeling degeneracies between the progenitor properties and red noise (i.e., systematics) modeled via Gaussian Processes (GPs).
We present 307 early time Type Ia supernova light curves from TESS sectors 1–50. We use this sample to characterize the shapes of the rising light curves and search for signatures of companion star interactions. We use Dynamic Nested Sampling to calculate the Bayesian Evidence for competing models and determine which light curves show evidence for or against the presence of a flux excess. In the majority of cases, the light curves cannot distinguish between models with or without a flux excess. However, we find 6 SNe that statistically disfavor a companion interaction model and 5 SNe that prefer the addition of a companion interaction model. We also calculate 3σ upper limits on the presence of companion signatures, which we use to control for orientation effects that impact the detectability of companions in individual SN light curves. Our results disfavor common progenitor systems with companions having Roche lobe radii > 40 R⊙ (separations > 7.5×1012 cm). These limits are in line with previous results based on stacking, although a unique contribution by TESS is 28 supernova light curves with individual limits on companion Roche lobe radii ≲ 10 R⊙ (separations < 1.9×1012 cm).
We apply smoothed particle inference analysis to characterize the structure, dynamics, morphology, and abundances of supernova remnants (SNRs). We present histograms and maps showing global properties of the remnant, including temperature, abundances of various elements, abundance ratios, and ionization age. For SNR DEM L71, our analysis confirms the high abundance of Fe within the ejecta of the supernova. Our results are generally consistent with a two-dimensional hydrodynamical model of the SNR. Comparing to predicted yields from Type Ia models available in the literature, we find that the abundance of various elements match those predicted by deflagration-to-detonation transition (DDT) models. In the case of the SNR W49B, comparison of the inferred abundance values and individual element masses with a wide selection of SN models also suggests that DDT Type Ia models are the most compatible, with Fe abundance being the major discriminating factor. Finally, although the centroid energy of the Fe Kα line of the entire remnant has been used to identify the progenitors of SNRs, our results show that caution must be used when employing it as the sole diagnostic for typing a remnant.
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I will summarize the evolution of stars towards supernovae, highlighting how the picture has changed in recent years with the role of binary interactions have a significant impact on the evolution, the supernova in it's eventual remnants. I will also discuss the most recent discoveries such as late-stage mass-loss events from binary interactions and other processes with the latest phases of evolution which have an imprint on the supernova itself.
One of the most uncertain aspects related to our understanding of the end points of stellar evolution is the link between the progenitor star and the nature of the supernova explosion that the progenitor will undergo. Even though hundreds of supernovae are discovered each year by optical surveys, these sources are usually too distant to resolve the ejecta and immediate surrounding of the exploded star. However, due to their long lifetimes and close proximity, supernova remnants which are the long lived structures that result from the supernova explosion of either a white dwarf or a massive star, provide us with a unique opportunity to study supernova explosion and dynamics up close and in detail. In this talk, I will highlight some recent advances that have been made in the understanding of supernovae and their progenitors using multi-wavelength studies of supernova remnants.
This is an exciting time for the discovery of SNRs in our and other nearby galaxies. I will report the discovery of J0624-6948, a low-surface brightness radio ring, lying between the Galactic Plane and the Large Magellanic Cloud (LMC). It was first detected at 888 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP), and with a diameter of ~196 arcsec. This source has phenomenological similarities to odd radio circles (ORCs). Significant differences to the known ORCs - a flatter radio spectral index, the lack of a prominent central galaxy as a possible host, and larger apparent size - suggest that J0624-6948 may be a different type of object. We argue that the most plausible explanation for J0624-6948 is an intergalactic supernova remnant due to a star that resided in the LMC outskirts that had undergone a single-degenerate type Ia supernova, and we are seeing its remnant expand into a rarefied, intergalactic environment.
Supernovae (SNe) are among the most powerful events that occur in galaxies, releasing a large amount of energy. They are major sources of nucleosynthesis products and thus contribute significantly to the chemical enrichment of the interstellar medium (ISM). The shock waves in supernova remnants (SNRs) heat and ionize the ambient ISM, evaporate molecular clouds, sweep up and compress colder denser gas, and thus form new interstellar structures. Moreover, particles are accelerated to relativistic energies forming the population of the highest-energy particles in a galaxy. I will give a summary of what we have learned so far about SNe and SNRs using past and current X-ray observatories.
Type Ia supernovae – the violent deaths of compact white dwarfs in close binary systems – are probes of dark energy and likely producers of most of the anti-matter (positrons) in our Galaxy. Despite their importance in different fields of astrophysics, we still argue about how they explode. Do they result from the explosion of a near-Chandrasekhar mass white dwarf via mass transfer from a companion? Or are they explosions of less massive white dwarfs, either mergers of two white dwarfs, perhaps triggered by helium shell detonations? Decades old, this remains the essence of the great debate of the progenitors and explosion mechanism of thermonuclear supernovae. In this talk, I will first summarise a modelling workflow (the “pipeline”) that connects rapid binary evolution progenitor models to supernova observables, via supernova explosion and nucleosynthesis simulations. I will then show how a growing number of remarkable shock-excited optical emission lines detected in the ejecta of young Type Ia supernova remnants can be used to constrain Type Ia explosions in a novel way.
Type Ia supernovae (SNe) are believed to mark the thermonuclear explosion of a white dwarf (WD), but the explosion mechanism is stil unclear. Recently a new theoretical model was proposed, for a binary WD, where the primary WD explodes via a double detonation (despite being of sub-Chandrasekhar mass) while the secondary WD survives and is ejected away. This has been called a "dynamically-driven double-degenerate double-detonation" or D^6. The discovery of hypervelocity stars with GAIA supports this scenario.
As part of our ongoing project of making the connection between the explosion physics and the remnant dynamics, we simulated in 3D the evolution of a D6 SN into the SNR phase, up to thousands of years after the explosion. Assuming a uniform ambient medium, we reveal specific signatures of the progenitor system and explosion mechanism. In particular the companion WD produces a large conical shadow in the ejecta. Our work shows the intrinsic diversity of thermonuclear SNe and their remnants.
Fluid-discontinuities in young supernova remnants (SNRs) offer a unique and clean methodology to constrain the properties of their originating explosion and the surrounding ambient medium. This differs from other theoretical frameworks that model the X-ray emission from SNRs, involving complicated non-equilibrium ionization calculations and uncertainty about the electron heating at their reverse-shocks. Here, we present an analysis of SNR 0509-67.5, a young remnant in the LMC, that only uses the kinematic properties of forward-shock (determined from HST multi-epoch observations) and reverse-shock (obtained from Seitenzahl et al. 2019). Hydrodynamic simulations, re-cast as similarity solutions are used to model the evolution of the SNR. These are then coupled to a Markov Chain Monte Carlo analysis to constrain the remnant’s age, explosion energy, the dynamical center of the explosion, and the density of the surrounding ambient medium. The constraint on the explosion energy is a first, from just the kinematics of the shock. We discuss the implications of our results in the broader context of Type-Ia progenitors and the degree of cosmic-ray acceleration in supernova shocks.
Collisonless shocks are observed in various environments in space. After the passage of collisionless shocks, charged particles are heated to different temperatures and then relax to the equilibrium state. However, this heating mechanism is not yet understood well.
Shockwaves formed by supernovae are one of the best systems for this study. The spatial variation of the electron temperatures behind the shocks provides us with the electron heating timescale. The excellent angular resolution of Chandra enables us to track this time variation of the electron temperature.
We observed the northwestern region of SN1006 with Chandra, which has filaments with thermal-dominated X-ray emission. We divide this region into several regions along the shock normal with a thickness of 15 arcsec or 0.16 pc each, and fit the extracted spectra with a non-equilibrium collisional ionization plasma model. As a result, the electron temperature is found to increase from 0.52-0.62 keV just behind the shock to 0.82-0.95 keV at the 60 arcsec (or 0.64 pc) distance from the shock front. In this presentation, we will discuss the electron heating mechanism working in this region.
Electron heating mechanisms are crucial to understanding the shock physics in supernova remnants (SNRs). Although the time variabilities of thermalized electrons provide direct information on the energy change, there are few observations of such variabilities (e.g., Patnaude & Fesen 2007). We present the discovery of gradually-brightening thermal X-ray emission found in Tycho's SNR obtained with Chandra within 2000-2015. The emission exhibits a knot-like feature associated with Hα filaments. The knot spectra can be reproduced by a non-equilibrium ionization model with the solar abundance, indicating that the knot originates from a forward-shocked interstellar medium. Our spectral analysis also reveals a significant increase in electron temperature over 15 yr. Comparing the calculation of equilibration timescales of electron temperatures for various cases, the electron-to-proton temperature ratio (i.e., β) immediately downstream of the shock is required to be smaller than 0.15 to reproduce the observed change in the electron temperature. Our result suggests collisionless heating with efficiency consistent with or higher than previous Hα observations (e.g., Ghavamian et al. 2001).
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Young supernovae remnants (SNR) are believed to be the main sites of galactic cosmic ray production, with X-ray synchrotron dominated spectra in the vicinity of their shock wave. While a faint signature left by shocked interstellar medium (ISM) should be found in these spectra, proofs for such an emission in Tycho's SNR have been lacking. We try to detect it by performing an extended spectral analysis of five regions behind the blast wave of Tycho's SNR using Chandra archival data. We use Bayesian inference to perform extended parameter space exploration and sample the posterior distribution of a variety of models of interest. We use the marginalized likelihood as our main metric to compare and evaluate the models that best describe the spectra. According to our analysis, composite models with one non-thermal component modelling synchrotron emission and two thermal models modelling respectively ejecta emission and shocked ISM are the most adequate at reproducing the spectral features in all regions. The properties of the shocked ISM we detect this way are consistent with values found previously in the literature.
Among Ia's supernova remnants (SNRs), Tycho's SNR (Tycho) is considered to be a typical remnant from the viewpoints of almost spherical shape and unique density for ambient medium. However, recent results of Tycho’s radio and X-ray observations show azimuthal variability of shock motion and CO observation suggest Tycho is surrounded by cloud swept by wind-like cavity. Moreover reanalysis of Tycho's Chandra data show that since around 2007 Tycho's shock is experiencing substantial deceleration that infer interaction with molecular cloud. From these information, knowing Tycho's age, we can strictly give a constraint on Tycho's environment.
In this study, from the angular size of forward shock we use the correspondent values for low-density in cavity and distance (to the earth) which is necessary to convert proper motions to physical values. Using the correspondent values, we calculate the evolution of Tycho's shock using hydro simulation with a range of parameters for environments, compare the results with observation data and search for best-fit parameters using chi squared for each region. In this talk, I will present the background of Tycho, and preliminary results.
Observations with HST/WFC3 and with the Binospec spectrograph on the MMT have provided far more detailed information about the physical parameters of radiative shock waves in the Cygnus Loop than was previously available, including shock speeds, ram pressures, pre- and post-shock densities and magnetic fields. It has long been thought that such shocks adiabatically compress the pre-existing cosmic ray electrons to produce radio emission. We compare that picture with shock reacceleration theory and with the observed radio emission, extending that to gamma-ray emission from compressed cosmic ray protons.
Radio synchrotron emission of supernova remnants (SNRs) is usually analyzed assuming homogeneous environment in order to obtain the surface brightness-to-diameter (Σ−D) dependence. The Milky Way (MW) SNR samples have a high data scatter and the main challenge is to explain their observed Σ−D slopes. We examine the Σ−D evolutionary paths, considering they might be highly affected by clumpy environment. In order to investigate the SNR evolution through the clumpy medium (CM), we utilized a model of synchrotron emission in hydrodynamic (HD) simulations of the SNRs. The simulations are carried out in environments of different density, including a variety of clumpy media. From these simulations, we developed a semi-analytical 3D spherically-symmetric model of the SNRs HD evolution in CM. The results show that after entering the CM, SNR brightness initially enhances, but afterwards the Σ−D slope steepens, shortening the lifetime of SNR synchrotron evolution. The comparison of the simulated and the MW SNR samples imply that the significant flattening and scatter of the Σ−D relation at D ≈ 13–50 pc originates in sporadic emission jumps of individual SNRs.
Some extended sources, among which we find the supernovae remnants, present an outstanding diversity of morphologies that the current generation of spectro-imaging telescopes can detect with an unprecedented level of details. However, the data analysis tools currently in use in the high energy astrophysics community fail to take full advantage of these data : most of them only focus on the spectral information without using the many spatial specificities or the correlation between the spectral and spatial dimensions. For that reason, the physical parameters that are retrieved are often widely contaminated by other components. In this talk, we will explore a new blind source separation method exploiting fully both spatial and spectral information with X-ray data, and their correlations. We will begin with a presentation of the method, then we will present its application to the search for thermal emission in the Crab nebula, where it has never been observed with certainty in X-rays.
We construct a turbulent model of the Crab Nebula's nonthermal emission. The present model resolves a number of long-standing problems of the Kennel-Coroniti model: (I) the sigma problem, (II) the hard spectrum of radio electrons, (III) the high peak energy of gamma-ray flares, (IV) and the spatial evolution of the infrared (IR) emission.
The fast shocks in supernova remnants are known to accelerate particles to extremely high energies. The acceleration process is closely tied to the magnetic field structure in the shock region. This, in turn, can be modified considerably by the shock. Synchrotron emission from the shock regions provides crucial details about the magnetic field strength and orientation through its polarization. Radio polarization studies of several SNRs have provided important maps of the field orientation, and these provide clues about the connection with particle acceleration. Due to the rapid losses of the highest-energy particles, however, X-ray polarization measurements yield magnetic field information from particles much closer to the acceleration sites, allowing us address questions about acceleration efficiency dependence on shock obliquity, levels of turbulence in the fields, and acceleration of particles at the reverse shock. Here I discuss IXPE studies of SNRs, including results from an early investigation of Cas A and plans for upcoming studies of other young SNRs.
TBD
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Supernova SN 1987A is often considered the poster child of core-collapse supernova, whose blue supergiant progenitor was born from a stellar merger. Recent studies also showed that other peculiar Type II SNe like 87A, may also have been explosions of massive blue supergiants born from stellar mergers. While these studies were specifically geared for 87A-like SNe, the vast parameter space of binary systems that experience post-main sequence mergers is still to be investigated. Using MESA, we evolve stellar models across a range of initial binary parameters through the merger phase, until near Fe core-collapse. For this we build a 1D merger scheme based on 3D hydrodynamic simulations, which mimics the mixing of the secondary main-sequence star in the common envelope. Such post-merger stars may also leave tell-tale signatures in the surface abundance patterns and HR diagram positions in observed stellar populations. The final structure of the star before explosion will also be radically different from other hydrogen-rich SNe progenitors. In this talk, I will present the first results of this exploratory study on massive binary-merger progenitors and their SNe.
We propose that WD mergers produce highly-magnetized, uniformly-rotating WDs, of which many have near-Chandrasekhar masses. We simulated multidimensional hydrodynamical explosions of a hydrostatic model of a cold C/O WD with a hot envelope, generated nucleosynthetic yields, and calculated synthetic optical spectra. The spectra correlate to type Ia events and lack observable companion signatures.
Jets!
Intermediate Luminosity Optical Transients (ILOTs) are a group of stellar outbursts in the energy gap between novae and supernovae. Luminous Red Novae (LRN) are a subgroup of ILOTs that are suspected to be stars that erupt as a result of a merger event (“merger-burst”). V838 Mon is a well known object in this class and its 2002 outburst is considered as a LRN prototype. It was modeled as a merger of 8 solar mass main sequence star with a 0.3-1 solar mass secondary young stellar object. In this study we assume that the late stage of a merger results in a thick accretion belt of shredded matter. We simulate this belt as a Keplerian thick accretion disk surrounding the primary. This disk is unstable and undergoes collapse and depletion. We investigate the details of such a process and compare it to common ILOTs observations. We find that for the first ~60 days the accretion rate, light curve and temperature of such a process are in good agreement with observations of V838 Mon and other ILOTs. We suggest that this model can be used to gain insights into the late stages of LRN and other ILOTS.
We build a bipolar explosion by three numerical phases (Hydrodynamical simulations). These might result from a common envelope evolution (CEE). However, for the present study the only important phase are the general bipolar explosion with dense equatorial gas and fast bipolar outflows. We obtain the light curve of core collapse supernave and compare to observations. we calculate the light curve for different angels and different opacities.
Mixed Morphology supernova remnants are characterized by their shell-type radio emission whereas their X-ray emission is center-filled. These remnants are often associated with molecular clouds producing gamma rays. Two main models have been proposed to reproduce the X-ray emission: 1) Thermal conduction in the remnant interior or 2) Ambient dense cloudlets surviving the passage of the main blast wave allowing for evaporation of the dense cloudlets which fill the interior. In what concerns their optical emission, there are no general studies on that emission for this type of remnants even if the presence of dense cloudlets (Model 2) predict the optical emission of those cloudlets as well as the presence of induced shocks in them.
We have undergone the task of studying the radio, archival X-ray emission and optical emission and derived kinematics of the cloudlets for Galactic and LMC Mixed Morphology remnants. We show our results on two cases . By using a freely available Python code developed by Leahy & Williams (2017), we can model the remnant evolution. In both cases, Model 2 explain quite well the characteristics of those remnants.
Finding the unbound, runaway companions to supernova remnants is key to understanding the binary progenitors of supernovae. We present population synthesis predictions for the kinematic and photometric properties of unbound companions, and describe how these predictions can be applied to companion searches in precise proper motion surveys such as Gaia.
We present UV imaging (in 3 bands, over 1800-1300 Ang) and soft x-ray (0.35-5.0 keV) spectroscopy of several segments of the Cygnus loop, each ~30' in diameter, covering a part of NGC6995 (the eastern veil), and the southern break-away region, using Astrosat/UVIT and SXT instruments. Wherever available, we compared the UVIT/FUV images with archival FUV images from the Ultraviolet Imaging Telescope, with NUV images from GALEX, and with IUE spectroscopic data. The x-ray spectra for some of the southern segments is well fitted by multicomponent models comprising shocked, heated gases with non-equilibrium ionization, coupled with emission via charge exchange reactions, although the contribution of the latter seems to vary across the loop. We discuss our findings in the context of the progenitor of the SNR, the nature of the ISM, and the various models of shock/CSM/ISM interaction.
We present and discuss two new radio-faint supernova remnants, G116.6-26.1 and G121.1-1.9, discovered in the course of the SRG/eROSITA All-Sky Survey. Both of them feature large size, close to circular shape and soft thermal X-ray spectrum. While the first one is probably located in the hot and tenuous gas of the Galactic halo, which would naturally explain faintness of the observed radio emission, the latter one is located in the Galactic disc, so that the lack of radio and optical counterparts appears to be more puzzling. Both objects are likely associated with SN Ia explosions, because of the off-disc location of G116.6-26.1 and hints of an iron-rich core for G121.1-1.9. Thanks to the conjectured low density of their environments, these objects offer great opportunities to study thermal and ionization equilibration processes in spatially resolved manner. G121.1-1.9 might be a rare Galactic example of the population of supernova remnants with the iron-rich core observed in Magellanic Clouds. We discuss how these objects can be used to probe non-equilibrium processes and physical conditions in the hot phase of the Galactic disc and Galactic halo.
We would like to talk about our recent studies of X-rays and shocked molecular clouds traced by radio-line emission (CO) in supernova remnants. Multiwavelength studies using Chandra and ALMA allow us to reveal the efficient acceleration mechanism of cosmic-rays and the shock-ionization processes in Galactic/Magellanic supernova remnants at a fine resolution of ~1-6 arcsecond for the first time. The shock-cloud interaction enhances turbulent magnetic up to mG that causes the synchrotron X-ray limb-brightening on the surface of the shocked cloud, as well as the short-time flux variation of the X-rays. The hard X-rays from high-temperature plasma will be also efficiently produced by the reflected shocks. The spatially resolved X-ray spectroscopy following the CO cloud distribution holds a key to understanding the spatial variation of thermal plasma conditions. Moreover, an expanding shell of neutral gas in Type Ia supernova remnants provides alternative evidence for the single-degenerate origin of the Type supernovae. In the presentation, we also discuss future perspective for combining studies of X-ray and radio-line observations.
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Supernova remnants play a key role in galaxy evolution and regulation of the birth of new generation of stars. Massive X-ray binaries are young stellar systems that provide important tracers of star formation in distant galaxies, and are the progenitors of some classes of gravitational sources. By the time a neutron star (NS) in a massive X-ray binary begins to accrete material from its companion, evidence of the supernova that formed the neutron star usually disappears (as the visibility time of SNR is only a few 10^4yr, much less than the life-times of high-mass XRBs). Finding such rare systems provide insights into the birth properties and early evolution of NSs. Especially, these objects are ideal probes for the physics of accretion onto a NS at early evolutionary stages, and can probe NS birth spins and magnetic fields. A handful of such peculiar systems have been found where the massive neutron star X-ray binary is found near the geometrical centre of its natal supernova remnant. I will summarise recent results in this regard obtained with the help of X-ray, radio and optical observations and discuss future directions.
Symbiotic systems belong to an important group of wind-interacting binaries in which a compact object, e.g., a white dwarf (WD), accretes mass from a powerful wind of an evolved red giant companion. These systems have been invoked as being potential progenitors of a fraction of SN Ia. I will highlight results from high-angular resolution multi-wavelength observations, and of 3-D hydrodynamical models of focused wind-accretion showing that understanding of the characteristics of the accretion onto the WD, and of the surrounding environment including sporadic mass-loss events (e.g., outbursts and jet activity), is a crucial first step for determining the precursor conditions potentially leading to SN Ia explosions.
The Large Magellanic Cloud (LMC), at a distance of 50 kpc, is so nearby that its SNRs can be studied with high resolution and their underlying stellar population can be resolved to investigate their relationship with the SNRs' progenitors. The Type Ia SNRs in the LMC have been identified by their Balmer-dominated shells, SN ejecta abundances derived from X-ray spectra, spectra of their SN light echoes, and Pop II stellar environments. The core-collapse SNRs can be identified by their pulsars and pulsar-wind nebulae, and their star-forming stellar and interstellar environments. We find recently that small dense nebular knots are frequently seen in young Type Ia SNRs in the LMC. Are these knots of circumstellar or interstellar origin? To answer this question, we examined archival Hubble Space Telescope images of SNRs in the LMC. We compare the characteristics of nebular knots in core-collapse SNRs with those in Type Ia SNRs and present the results in this talk.
In this talk, I will discuss the use of supernova remnant and stellar population surveys in the Local Group galaxies to constrain progenitor scenarios of supernovae. Many key details about supernova progenitors remain unknown, such as the precise mass range of massive stars that lead to core-collapse supernovae, and the threshold mass and binary companion of CO white dwarfs that trigger Type Ia supernovae. A key information that can validate specific theoretical progenitor models is the rate at which stars explode at a given progenitor timescale, known as the delay-time distribution (DTD), which is directly related to the binary evolution physics of supernova progenitors. This DTD can be accurately measured with supernova remnant surveys and observations of their host galaxy's stellar population and interstellar medium environments. Related to this, I will also introduce the ongoing Local Group L-Band Legacy Survey (LGLBS) -- poised to be the most sensitive radio survey of the northern Local Group galaxies, and expected to yield a highly complete catalog of supernova remnants, HII regions and their cloud-scale atomic ISM environments.
Neutron stars and black holes – the compact objects left over from supernova explosions – exhibit a wide range of properties, and their analysis can provide many insights into the explosive mechanisms in and progenitors of supernova explosions. Associations between SNRs and compact objects are incredibly useful as they can constrain the properties of both classes of objects, and over the past few decades astronomers have identified and studied dozens of compact objects in SNRs. Although most of these objects are neutron stars (many that power extended PWNe), the mechanisms responsible for the formation and the birth frequency of different types of neutron stars -- pulsars, magnetars, and central compact objects—remain uncertain. In this talk, I will summarize our knowledge about these young (<30 kyr) compact objects, highlighting recent research that has provided useful insights about the observational properties and theories behind the formation of these objects, as well as their relationships with the SNRs they are embedded in.
Since the day of its explosion, supernova (SN) 1987A was closely monitored to study its evolution and to detect its central compact relic. The detection of neutrinos from the SN strongly supports the formation of a neutron star. Besides the detection in the ALMA data of a feature that is somehow compatible with the emission arising from a proto-pulsar wind nebula (PWN), the only hint for the existence of this elusive compact object is provided by the detection of hard X-ray emission in NuSTAR spectra. I present new results of the simultaneous analysis of multi-epoch observations of SN 1987A performed by Chandra, XMM-Newton and NuSTAR. I compare actual data with a 3D MHD simulation of SN 1987A. Both the phenomenological analysis and the comparison with the MHD model provide strong arguments against either a thermal origin for the hard X-ray emission. I show that a heavily absorbed power-law, perfectly consistent with the emission from a PWN embedded in the heart of SN 1987A, is needed to properly describe the observed X-ray spectra. Thanks to the results obtained, I also infer some physical characteristics of the pulsar and the broad-band spectrum of its nebula.
SNR 0540-69.3 is the second youngest supernova remnant (SNR) in the Large Magellanic Cloud (LMC), older than only SN1987A, and it is often called a “twin” of the Crab nebula because of its pulsar wind nebula (PWN). Spitzer and Herschel fluxes of SNR 0540-69.3 indicate the presence of dust emission at the center of this SNR, but their angular resolutions are insufficient to resolve the dust clumps and PWN structures. To investigate the dust content and to resolve it from the PWN, we obtained a high-resolution ALMA Band 3 (100 GHz) observation of the PWN, and compared it with Chandra, HST, Spitzer, and ATCA images. The ALMA image shows extended filaments, and also several bright clumps around the projected position of the pulsar. These structures are resolved for the first time.
Circumstellar material (CSM) around supernova remnants (SNR) is important for studying their progenitors since CSM contains elements produced in stars and blown out by stellar winds. While abundances of lighter elements such as nitrogen and oxygen critically reflect the history of massive stars (Maeder et al. 2014), the detection of their fluorescence lines in X-ray has been limited so far due to the lack of effective areas in the soft band. In this talk, we will report on a high-resolution spectral analysis of the magnetar-hosting SNR, RCW 103 with the reflection grating spectrometer onboard XMM-Newton. We detect the nitrogen line for the first time in this SNR and obtain a high abundance ratio of nitrogen to oxygen (N/O~4) from the CSM component. By comparing the results to stellar evolution models (Ekstrom et al. 2012; Luo et al. 2022), we constrain the progenitor of RCW 103 to be a low mass (~12M⊙) and medium rotating-velocity (~100km/s) star. The results play an important role in estimating the origin of magnetars: the dynamo effect (Thompson & Duncan 1993), which is the most popular magnetar-formation hypothesis, is less plausible and another mechanism might be required.
Central Compact Objects (CCOs) represent an enigmatic class of isolated neutron stars. Sitting near the centres of young core-collapse supernova remnants (SNRs), they are exclusively visible and studied in the X-ray regime. So far, there has been no firmly identified CCO counterparts at any other wavelengths. However, ground-based observations detected an optical structure around the location of CXOU J085201.4-461753, the CCO in the heart of Vela Jr. SNR. This object is the only Galactic member of the CCOs class around which optical nebular emission has been detected to date. Originally thought to be Hα emission, the nebulosity was not detected in dedicated narrow-band HST observations. Using the new high-resolution data obtained using the Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT), we aim to address the big question on whether the nebula is associated with the CCO in Vela Jr. or just a positional coincidence.
SNe Ia may originate from (1) white dwarfs accreting from binary companion stars or (2) mergers of two white dwarfs. If a surviving companion or a dense circumstellar medium (CSM) from the progenitor’s mass loss is detected, the origin of accreting white dwarf can be affirmed.
To date, no surviving companion has been unambiguously confirmed in the Milky Way. We have thus turned to the five young Type Ia SNRs in the Large Magellanic Cloud (LMC). To search for surviving companions in these SNRs, we have used HST images to produce color-magnitude diagrams for their underlying stellar population to compare with the post-impact evolutionary tracks of surviving companions. We have also used archival VLT MUSE spectra to search for stars with high radial velocities. From these analyses, we identified possible surviving companions of SN progenitors within SNRs Ia outside the Milky Way for the first time. We have also used VLT MUSE spectra of these SNRs to discover forbidden-line emission regions and used HST Hα images to resolve them into dense nebular knots that most likely belong to a CSM. The origin of accreting white dwarf for SNe Ia could be more prevalent than previously thought.
We present the first direct measurement of the proper motion of pulsar J1124--5916 in the young, oxygen-rich supernova remnant G292.0+1.8. Using deep {\it Chandra} ACIS-I observations from 2006 and 2016, we measure a positional change of 0$\farcs$21 $\pm$ $0\farcs05$ over the $\sim$ 10 year baseline, or $\sim$ $0 \farcs 02$ yr$^{-1}$. At a distance of 6.2 $\pm$ 0.9 kpc, this corresponds to a kick velocity in the plane of the sky of $\mathrm{612\pm 152\,km \, s^{-1}}$. We compare this direct measurement against the velocity inferred from estimates based on the center of mass of the ejecta. Additionally, we use this new proper motion measurement to compare the motion of the neutron star to the center of expansion of the optically emitting ejecta. We derive an age estimate for the supernova remnant of $\gtrsim$ 2000 years. The high measured kick velocity is in line with recent studies of high proper motion neutron stars in other Galactic supernova remnants, and consistent with a hydrodynamic origin to the neutron star kick.
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Over the last 30 years we have made great strides in identifying the type of supernovae from their remnants. To do this we have now a number of tools at our disposal, such as composition as probed by X-ray spectroscopy, morphology, the presence or absence of non-radiative Halpha emission, and in a number of cases light echoes associated with SNRs, which (luckily!) directly confirmed our long held suspicions. I will briefly review these tools, but would like to also like to point out a few flies in the ointment. I would like to close off with recent results on the expansion of Cas A, and put it in the context of its circumstellar medium, and what this may tell us about its progenitor.
Studies of SNRs in different galaxies provide a more representative picture of their populations and their dependence on their environment. This is important for understanding their evolution and addressing their role in feedback in a wide variety of galactic environments. We present our results from a systematic study on the SNRs populations in nearby spiral galaxies, focusing on NGC7793, based on Hα and [S II] images. Having accounted for incompleteness effects, we derive their Hα and the joint Hα-[S II] luminosity functions. We also present new X-ray SNRs in NGC 7793 and we examine their environment using IFU data. Prompted by the limitations of the standard [S II]/Hα diagnostic, we have developed new diagnostics for identifying SNRs based on combinations of optical emission-line ratios and machine learning methods. We discuss how these diagnostics can be used to mitigate biases in [S II]/Ha-selected SNRs. In addition, we introduce a formalism for the derivation of theoretical Hα and Hα-[S II] luminosity functions. This is the first step for the construction of population synthesis models of optical SNRs.
SN 1987A provides us with a unique opportunity to study in great detail the birth and the early evolution of the supernova remnant. The 14-year XMM-Newton monitoring of SN 1987A reveals a steady increase in the 3-8 keV flux, but a recent decrease in the 0.5-2 keV flux. Along with the decreasing emission measure of the low-temperature plasma, this indicates the blast wave has now left the main equatorial ring, and is still propagating into the high-latitude gas. The Fe K lines are clearly detected in SN 1987A. The high centroid energy (≥ 6.65 keV) corresponds to a high plasma temperature ~ 3 keV, and a recent decrease in the centroid energy could be related to the newly shocked Fe-rich ejecta clumps. The high energy resolution of RGS and the wide energy coverage of EPIC-pn allow us to investigate the continuous temperature distribution of the X-ray gas in SN 1987A, which shows great consistency with the MHD simulation results. The NuSTAR observations reveal an excess of the 10-20 keV flux with respect to the pure-thermal spectral model, which is best reproduced by a heavily absorbed power law. This provides evidences for a pulsar wind nebula embedded in the heart of SN 1987A.
Based on our Chandra HETG and ACIS imaging-spectroscopic observations, we present the latest evolution of the X-ray remnant of SN 1987A. Recent changes in electron temperatures and volume emission measures suggest that the shocks moving through the inner ring have started interacting with less dense circumstellar material, probably beyond the inner ring. We find significant changes in the X-ray line flux ratios (among H- and He-like Si and Mg ions) in 2018, consistent with changes in the thermal conditions of the X-ray emitting plasma that we infer based on the broadband spectral analysis. Post-shock electron temperatures suggested by line flux ratios are in the range ~0.8 - 2.5 keV as of 2018. The soft-band X-ray flux has been on a slight declining trend (~10%) between 2018 - 2021, while the hard-band counterpart has been linearly increasing by ~10% / yr. We do not yet observe any evidence of substantial abundance enhancement, suggesting that the X-ray emission component from the reverse-shocked metal-rich ejecta is not yet significant in the observed X-ray spectrum. We also do not yet detect X-ray radiation from the compact source at the center in the 0.5 - 8.0 keV energy range.
Interpreting observations of supernova remnants from radio to gamma-rays requires a detailed understanding of how shocks accelerate particles over the course of their evolution. We present a fast, multi-zone model of particle acceleration that self consistently accounts for magnetic field amplification and shock modification due to the presence of non-thermal particles. By incorporating results from state-of-the-art simulations, we use this model to reproduce key features in the multi-wavelength emission from a variety of astrophysical explosions. These features include the the complex radio and X-ray emission from extragalactic supernovae (“radio supernovae”), the gamma rays detected from the recent outburst of recurrent nova RS Ophiuchi, and the steep radio and gamma-ray spectra inferred from Galactic supernova remnants.
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Type Ia supernovae (SNe) are among the most common astrophysical transients, yet their progenitors are still unknown. While we generally agree that SNe Ia arise from the thermonuclear explosion of a white dwarf (WD), that is where the current consensus ceases. Exactly what type of WD is exploding, how it explodes, and in what environment are all still matters of active research. I will discuss the current status of the field from a theory perspective and focus on what observations (in what wavelengths and at which epochs) are needed to distinguish between leading models.
Cataclysmic Variables (CVs) and Symbiotic Binaries are close (or not so close) binary star systems which contain both a white dwarf (WD) primary and a larger cooler secondary star that typically fills its Roche Lobe. The cooler star is losing mass through the inner Lagrangian point of the binary and a fraction of this material is accreted by the WD. We report on the evolution of thermonuclear runaways (TNRs) in the accreted material. We have followed the TNRs on both carbon-oxygen (CO) and oxygen-neon (ONe) WDs. We accrete solar matter until the TNR is ongoing and then switch the composition in the accreted layers to a mixed composition: either 25% WD and 75% solar or 50% WD and 50% Solar matter. We find that the amount of accreted material is inversely proportional to the initial 12C abundance. Thus, accreting solar matter results in a larger amount of accreted material to fuel the outburst; much larger than in earlier studies where a mixed composition was assumed from the beginning of the simulation. Our most important result is that these simulations eject significantly less mass than accreted and, therefore, the WD is growing in mass toward the Chandrasekhar Limit.
For the 450th anniversary of the Tycho SNR, we propose a new analysis of the three dimensional ejectas dynamics with Chandra's X-ray data. New methods are used to study the velocity in the plane of sky and in the line of sight, in order to reconstruct 3D vectors field and study the asymmetries of the expansion. In the plane of sky, we developed a new tool to measure the shift of two dimensional small features matching their morphology using a Poisson likelihood. This new method allows to generate hundreds velocity measures instead of the usual tens. For the line of sight velocity, a blind source component analysis (GMCA) is used. This method separates the cube on various components, each with an image and associated spectrum, based on the spectro-morphological differences. For the Tycho SNR, blue and redshifted components are obtained. This allows us to finally reconstruct a map of dynamics based on Doppler line shift. The measurement of hundreds of velocity vectors allows us to put better constraints on the progenitor system, explosion model and compare the impact of the explosion asymmetries with respect to an inhomogeneous CSM.
Despite intense scrutiny, the SN Ia progenitor scenario remains uncertain. Recently, the dynamically driven double-degenerate double-detonation (D6) scenario has been looked to as one of the most promising progenitor scenarios for SNe Ia. The scenario predicts the existence of a fast moving, over-luminous white dwarf residing within the remnant of the explosion. We present a high precision astrometric survey of the SN 1006 galactic supernova remnant, the only remnant in which a surviving D6 companion star would likely be observable. In this talk we confront the D6 scenario with our findings, focusing on the constraints posed by these results as well as the limitations of our search.
Type Ia supernova remnants allow a unique perspective into the interaction between ejecta and circumstellar medium. Remnant properties such as radius and centroid energy of Fe Kα in the X-ray spectrum are determined by this process. We model the interaction between Chandrasekhar and sub-Chandrasekhar Type Ia supernova ejecta in circumstellar ejecta profiles up to an age of 5000 years. We generate synthetic X-Ray spectra from these supernova remnant models and compare their bulk properties at different expansion ages with observations from Chandra and Suzaku. We attempt to establish quantitative limits on circumstellar environments in which Type Ia supernova can occur to exclude potential progenitor scenarios.
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Puppis A is a 4000 year-old core-collapse supernova remnant (SNR), visible as one of the brightest extended X-ray sources on the sky. The eROSITA instrument onboard the SRG satellite is ideal for the investigation of such extended objects on degree scales thanks to its large effective area, its good spectral resolution, and its quasi-unlimited field of view in survey or scanning mode. Using data acquired by eROSITA during its initial calibration and performance verification phase, we have conducted the most sensitive spatially resolved spectroscopic study of the entirety of the X-ray emission of Puppis A.
In this talk, we will present the spatially resolved properties of hot X-ray emitting plasma throughout Puppis A which we have constrained using our eROSITA data set. Our findings include the observation of large-scale gradients in foreground absorption and plasma temperature, and the identification of several regions that have recently interacted with the forward or reverse shock. Furthermore, we have used abundance maps of typical ejecta elements to identify all prominent X-ray emitting ejecta clumps in the SNR.
We present first results from the Chandra Large Project observation of the Large Magellanic Cloud (LMC) supernova remnant N132D. N132D was observed in 28 separate observations during 2019 and 2020 totaling more than 878 ks. We compare the new data to archival data acquired in 2006 to measure the expansion of the forward shock in the bright southern rim to be 110 +/- 23 over the 14.15 yr baseline which corresponds to a velocity of 1850 +\- 386 km/s. We measure a shock velocity of 3435 +\- 374 km/s for a feature in an apparent blowout region in the north-east and use this value to estimate the deceleration of the shock wave in the molecular cloud interaction region. The average temperature inferred from X-ray spectral fits to regions in the southern rim is 0.99 keV which corresponds to a shock velocity of 855 +/- 100 km/s assuming full equilibration between electrons and ions. Our measured shock velocity suggests that the ratio of T_e/T_{ion} is closer to 0.12.
The set of Small Magellanic Cloud (SMC) supernova remnants (SNRs) is small (20 SNRs) but this is observationally the most complete set of SNRs in the local group of galaxies. These SNRs have been surveyed in X-rays by XMM-Newton, yielding a set of temperatures and emission measures for the shocked gas. Spherically symmetric supernova remnant evolution models have been developed based on hydrodynamic simulations, and which include the evolution of the reverse shock. These models are applied to the SMC SNRs to estimate ages, explosion energies, and circumstellar medium densities. The results will be discussed and compared to similar studies for Galactic and LMC SNRs.
The X-Ray Imaging and Spectroscopy Mission (XRISM), an international collaboration led by JAXA and involving major participation from NASA and ESA, will employ an advanced X-ray observatory with capabilities to carry out a science program to address some of the important questions of present-day astrophysics. XRISM's Resolve instrument is a high-resolution, non-dispersive X-ray spectrometer operating between 0.3-12 keV. It is the core instrument on XRISM, providing high-resolution spectroscopic capability (~ 5 eV). The Xtend instrument will provide complementary CCD observations over a 38'x38' field of view. In this talk, I will provide a brief mission status update and highlight some of the supernova remnant science that XRISM will do. I will discuss the SNR targets that have been chosen for the Performance Verification (PV) phase of the mission, as well as discuss the policies governing the General Observer (GO) phase of the mission.
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