arXiv subjects

Gilles Ferrand

Publications and source records attributed to Gilles Ferrand.

At least 19 recordsLinked to original sources

arXiv2026

Ejecta clumps revealed by study of reverse-shocked ejecta through MUSE integral field spectroscopy of SNR 0509-67.5

We report the discovery of a spatially resolved clumpy ejecta structure in the reverse-shocked ejecta of SNR 0509-67.5, revealed through multiple faint and broad forbidden coronal emission lines in deep MUSE observations. We also identify two new broad coronal emission lines not reported before in this remnant, [Fe xi] 7894 A and [Fe x] 6374.5 A , which extend the set of previously reported [Fe xv] 7059.59 A, [Fe xiv] 5302.86 A , [Fe ix] 8236.55 A , [Ca xv] 5695 A, and [S xii] 7611.0 A. Near-continuous ionisation states of Fe allow us to follow the ionisation progression behind the reverse shock. We use a 1D analytical model to evolve Fe charge states following reverse shock interaction to compare with observations, indicating the need for preshock clumping or over-density in order to reproduce the observed surface brightness of the [Fe xiv] line. Additionally, we report the spatially resolved distribution of ejecta clumps and show that reverse-shock interaction drives their compression and fragmentation. We also find a clear trend of decreasing velocity width with increasing Fe ionisation state, from the broadest [Fe ix] emission to the narrowest [Fe xv], with intermediate-ionisation species ([Fe x], [Fe xi], [Fe xiv]) showing intermediate widths. Finally, we compare our observations to a dynamically driven double-degenerate double detonation (D6) 3D remnant model at similar Fe and S ionisation states and conclude that the observed clumps are predominantly due to Rayleigh-Taylor instabilities.

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arXiv2026

Deep MUSE observations of SNR 0509-67.5 reveal a double degenerate merger progenitor

Deep MUSE observations of SNR 0509-67.5 reveal that the coronal [Fe\,\textsc{xiv}] $\mathrm{\lambda}$5303 emission line appears with either one or two velocity components across the entire remnant, arising from reverse-shocked ejecta moving toward and away from the observer. A supervised dense neural network classifies each spaxel and fits Gaussian profiles plus a linear function to the observed line emission. We measure a bulk Doppler velocity of $-1000\pm60~~\mathrm{km~s^{-1}}$, interpreted as the line-of-sight component of the primary white dwarf's orbital velocity in a double-degenerate merger. The red- and blue-shifted ejecta map shows a flattened edge along the north-eastern rim, consistent with the companion's shadow, indicating a binary companion was present at explosion. Modelling this feature as a cone anchored at the explosion centre and applying Bayesian inference, we recover the cone's orientation and half-opening angle. We then use the Eggleton Roche-lobe relation to infer properties of the companion. The companion was likely a ${\sim}0.6~\mathrm{M_\odot}$ white dwarf with radius ${\sim}9800$~km and orbital velocity ${\sim}1700~\mathrm{km~s^{-1}}$ at the time of explosion. Together, these results provide a complete dynamical picture of a Type Ia supernova progenitor system whose maximum-light spectrum is independently constrained by light echo observations.

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arXiv2026

A Systematic Study of Type Ia Supernova Remnants: Using Nucleosynthesis to Probe their Supernova Progenitors

We present the first systematic, spatially resolved X-ray spectroscopic study of a largely thermonuclear (Type Ia) sample of supernova remnants (SNRs), aimed at probing the explosion properties and progenitors through a comparison to a suite of nucleosynthesis models available in the literature. Our sample focuses on Galactic and LMC ejecta-dominated SNRs believed to be, or otherwise assumed to be, of thermonuclear origin. Using archival XMM-Newton observations (and Chandra for G1.9+0.3), we extract spectra from adaptively binned regions across each remnant and model the emission to constrain the plasma temperature, ionization timescale, and ejecta abundances. We then compare abundance ratios (relative to Si) to a library of 335 individual models spanning 11 commonly-used supernova nucleosynthesis simulation sets from the literature including seven thermonuclear and four core-collapse sets. Across the sample, we find that individual remnants can be well matched by subsets of models, but no single model reproduces all measured elemental ratios at once. As a result, the best fit model for a given object is typically set by a selection of well-fitted abundance ratios, highlighting both the strength and limitations in yield-based model determination. For some SNRs, the abundance comparisons show better agreement with particular families of Type Ia SN explosions, including near-Chandrasekhar-mass delayed detonations, sub-Chandrasekhar-mass explosions, and dynamically driven double detonations, although these interpretations are not unique. Finally, we outline the need for model improvements, including refined nuclear reaction rates, higher dimensional treatment of mixing and turbulence, expanded metallicity coverage, and the exploration of non-standard supernova explosion energies.

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arXiv2026

Three-Dimensional Simulations of Type Ia Supernova Remnants I: Effects of a Main-Sequence Companion Star

Type Ia supernovae (SNe Ia) serve as one of cosmic standard candles, but their exact progenitor channel is still an open question. SNe Ia commonly come from binary star evolution. Therefore, one of the major differences among the proposed progenitor channels is whether there is a more-or-less intact companion star remaining at the time of explosion, which causes the SN ejecta to be more asymmetrical. As the SN ejecta evolved into supernovae remnants (SNR), the imprint formed by the companion interaction may affect the morphology of the SNR. In addition, the progenitor systems may have experienced different mass transfer histories and therefore led to formation of different circumstellar material (CSM) environments, which may also affect the early evolution of SNR. In this study, we use GADGET and RAMSES codes to simulate these physical effects and follow the evolution into early-phases of SNRs. In our simulations, we consider different ejecta models and track the element distribution. We compare our simulation with actual observations and conclude that despite some SNRs having morphology resemblance to our simulation results, their highly asymmetric expansion rates are hard to explain by interaction between SN ejecta and a companion star alone.

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arXiv2026

A MUSE View of the Optical Torus within the Supernova Remnant 1E 0102.2-7219

We present new MUSE Narrow Field Mode with Adaptive Optics observations of the optical torus surrounding a Central Compact Object (CCO) candidate within the oxygen-rich supernova remnant 1E 0102.2-7219 (E0102) located in the Small Magellanic Cloud. These data provide nearly an order-of-magnitude improvement in spatial resolution over previous MUSE Wide Field Mode observations. The improved spatial resolution resolved the previously identified torus into a cavity-like structure with a sharply defined inner edge and diffuse, outer filamentary substructure. The emission shows continuous velocity connectivity, broad intrinsic line widths, and co-spatial contributions from neutral and partially ionized species, including O I, Ne I, [O I], [O II], and [O III]. Spatially resolved line-ratio maps indicate that the emission arises from a multiphase, non-equilibrium medium rather than a single homogeneous component. Comparison with photoionization and shock models shows that no single-component model within the explored parameter space can simultaneously reproduce both the strong neutral and high-ionization diagnostics, indicating that multiple physical conditions must coexist. We favor an interpretation in which shocks propagating through density inhomogeneities in the ejecta shape the observed morphology and excitation, while also considering alternative mechanisms linked to the central source, binary evolution, or interaction with an embedded object within the remnant.

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arXiv2026

Probing the Diversity of Type Ia Supernova Remnants in 3-D Hydrodynamic Simulations with X-ray Spectral Synthesis

Type Ia supernovae (SNe), thermonuclear explosions of white dwarfs in binary systems, are widely used as standard candles owing to the empirical width-luminosity relation of their light curves. Recent theoretical and observational studies indicate a diversity of progenitor systems and explosion mechanisms. In the supernova remnant (SNR) phase, the diversity in Fe-K$\alpha$ centroid energies and line luminosities suggests variations in the underlying explosion mechanisms. X-ray spectra of SNRs, which trace shocked ejecta and the surrounding medium, are crucial diagnostics of progenitor systems and explosion physics. Thanks to recent advances in spectroscopy with XRISM, high-resolution X-ray spectroscopy enables 3-D diagnostics, including line-of-sight velocities. In this study, we perform 3-D hydrodynamic simulations of SNRs from six Type Ia explosion models: two each of pure deflagration, delayed detonation, and double detonation. Each model is evolved for 1000 years in a uniform medium, consistently accounting for non-equilibrium ionization. Our efficient numerical scheme enables systematic parameter surveys in full 3-D. From these models, we synthesize X-ray spectra with $\sim$1 eV resolution, exceeding XRISM/Resolve's spectral resolution. This work presents the first calculation of X-ray spectra for Type Ia SNRs derived from 3-D hydrodynamic simulations that follow the evolution self-consistently from the SN phase into the SNR phase. Our results show inter-model diversity in the X-ray spectra. Asymmetric, red- and blueshifted line profiles arise from the 3-D ejecta distributions. These findings demonstrate that 3-D SNR modeling can reproduce the observed diversity of Type Ia SNRs and provide qualitative constraints on progenitor systems and explosion mechanisms.

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arXiv2025

Revisiting the Supernova Engines in the 3C 397 and W49B Supernova Remnants

The nature of the supernova remnants (SNRs) 3C 397 and W49B has long been a subject of debate, with prior studies offering conflicting interpretations between thermonuclear and core-collapse scenarios. To help settle this debate, we present a systematic, spatially resolved, spectroscopic analysis of both remnants using XMM-Newton. By applying multi-component thermal models, we derive key physical properties including elemental abundances, ejecta temperatures, ambient densities, and explosion energetics. We compare the inferred metal abundance ratios to a wide range of core-collapse and thermonuclear nucleosynthesis models, including new models whose explosion energies differ from the canonical value of $10^{51}$ ergs. We find that the observed Fe/Si and Ca/Si ratios in both SNRs are best matched by certain thermonuclear models. However, no model fully reproduces the complete set of observed abundance patterns. In 3C 397, high Fe enrichment and spatial abundance variations suggest interaction with a dense progenitor environment, and W49B's composition is overall consistent with a thermonuclear origin; however both require a low energy ($\sim 10^{50}$ erg) supernova explosion. We additionally map the Fe K$\alpha$ line centroid energies and find a spread, with W49B falling within the core-collapse region -- highlighting both environmental complexity and the limitations of this diagnostic for supernova classification. Our results highlight the need for caution in relying on any single diagnostic or nucleosynthesis model for supernova typing, underscore the need for improved nucleosynthesis models, and motivate future high-resolution, high-throughput observations.

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arXiv2025

The role of the secondary white dwarf in a double-degenerate double-detonation explosion, in the supernova remnant phase

Type Ia supernovae (SNe) are believed to be thermonuclear explosions of white dwarf (WD) stars, but their progenitor systems and explosion mechanisms are still unclear. Here we focus on double degenerate systems, where two WDs are interacting, and on the double detonation mechanism, where a detonation of a helium shell triggers a detonation of the carbon-oxygen core of the primary WD. We take the results from three-dimensional SN simulations of Pakmor et al 2022 (arXiv:2203.14990) and carry them into the supernova remnant (SNR) phase, until 1500 yr after the explosion. We reveal signatures of the SN imprinted in the SNR morphology. We confirm the impact of a companion on the SNR: its presence induces a conical shadow in the ejecta, that is long lived. Its intersection with the shocked shell is visible in projection as a ring, an ellipse, or a bar, depending on the orientation. New, we test the case of a nested explosion model, in which the explosion of the primary induces the secondary to also explode. As the explosion of the secondary WD is weaker only the primary outer ejecta interact with the ambient medium and form the main SNR shell. The secondary inner ejecta collide with the reverse shock, which enhances the density and thus the X-ray emissivity. The composition at the points of impact is peculiar, since what is revealed are the outer layers from the inner ejecta. This effect can be probed with spatially-resolved X-ray spectroscopy of young SNRs.

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arXiv2023

Potential of the Cherenkov Telescope Array for studying the young nearby supernova remnants

Modern imaging atmospheric Cherenkov telescopes have extensively observed young nearby supernova remnants (SNRs), with ages of about 1000 years or less, in the very-high-energy (VHE) gamma-ray band. These efforts resulted in the detection of VHE emission from three young SNRs - Cassiopeia A, Tycho, and SN 1006 - and provided significant evidence for emission from the more distant Kepler's SNR. However, many questions on the production of VHE gamma rays in these remnants remain unanswered. Using detailed physical models for Tycho's SNR based on the CR-hydro-NEI code and physically motivated models for the other young nearby remnants, we simulated observations with the Cherenkov Telescope Array (CTA) of these gamma-ray sources. We highlight properties of these remnants accessible for investigation with future CTA observations and discuss which questions are expected to be answered.

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arXiv2022

The double detonation of a double degenerate system, from Type Ia supernova explosion to its supernova remnant

Type Ia supernovae (SNe) are believed to be caused by the thermonuclear explosion of a white dwarf (WD), but the nature of the progenitor system(s) is still unclear. Recent theoretical and observational developments have led to renewed interest in double degenerate models, in particular the "helium-ignited violent merger" or "dynamically-driven double-degenerate double-detonation" (D$^6$). In this paper we take the output of an existing D$^6$ SN model and carry it into the supernova remnant (SNR) phase up to 4000 years after the explosion, past the time when all the ejecta have been shocked. Assuming a uniform ambient medium, we reveal specific signatures of the explosion mechanism and spatial variations intrinsic to the ejecta. The first detonation produces an ejecta tail visible at early times, while the second detonation leaves a central density peak in the ejecta that is visible at late times. The SNR shell is off-centre at all times, because of an initial velocity shift due to binary motion. The companion WD produces a large conical shadow in the ejecta, visible in projection as a dark patch surrounded by a bright ring. This is a clear and long-lasting feature that is localized, and its impact on the observed morphology is dependent on the viewing angle of the SNR. These results offer a new way to diagnose the explosion mechanism and progenitor system using observations of a Type Ia SNR.

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arXiv2020

From supernova to supernova remnant: comparison of thermonuclear explosion models

Progress in the three-dimensional modeling of supernovae (SN) prompts us to revisit the supernova remnant (SNR) phase. We continue our study of the imprint of a thermonuclear explosion on the SNR it produces, that we started with a delayed-detonation model of a Chandrasekhar-mass white dwarf. Here we compare two different types of explosion models, each with two variants: two delayed detonation models (N100ddt, N5ddt) and two pure deflagration models (N100def, N5def), where the N number parametrizes the ignition. The output of each SN simulation is used as input of a SNR simulation carried on until 500 yr after the explosion. While all SNR models become more spherical over time and overall display the theoretical structure expected for a young SNR, clear differences are visible amongst the models, depending on the geometry of the ignition and on the presence or not of detonation fronts. Compared to N100 models, N5 models have a strong dipole component, and produce asymmetric remnants. N5def produces a regular-looking, but offset remnant, while N5ddt produces a two-sided remnant. Pure deflagration models exhibit specific traits: a central over-density, because of the incomplete explosion, and a network of seam lines across the surface, boundaries between burning cells. Signatures from the SN dominate the morphology of the SNR up to 100 yr to 300 yr after the explosion, depending on the model, and are still measurable at 500 yr, which may provide a way of testing explosion models.

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arXiv2020

3D modeling from the onset of the SN to the full-fledged SNR: Role of an initial ejecta anisotropy on matter mixing

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 investigated how a post-explosion large-scale anisotropy in the SN affects the ejecta distribution and the matter mixing of heavy elements in the remnant, during the first 5000 years of evolution. In the case of a spherically symmetric SN explosion without large-scale anisotropies, the remnant roughly keeps memory of the original onion-like layering of ejecta soon after the SN event. Nevertheless, as the reverse shock hits the ejecta, the element distribution departs from a homologous expansion, because of the slowing down of the outermost ejecta layers due to interaction with the reverse shock. In the case of a large-scale anisotropy developed after the SN, we found that the chemical stratification in the ejecta can be strongly modified and the original onion-like layering is not preserved. The anisotropy may cause spatial inversion of ejecta layers, for instance leading to Fe/Si-rich ejecta outside the O shell, and may determine the formation of Fe/Si-rich jet-like features that may protrude the remnant outline. The level of matter mixing and the properties of the jet-like feature are sensitive to the initial physical (density and velocity) and geometrical (size and position) initial characteristics of the anisotropy.

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arXiv2020

Modelling and simulations of supernova remnants: a short review focused on recent progress in morphological studies

Supernova remnants (SNRs) are the outcome of supernovae (SNe, either core-collapse or thermonuclear). The remnant results from the interaction between the stellar ejecta and the ambient medium around the progenitor star. Young SNRs are characterized by strong shocks that heat and ionize the gas, generate magneto-hydrodynamic turbulence, and accelerate particles to relativistic energies. They radiate at all wavelengths, especially in the X-ray domain, where spectro-imaging observations can provide a wealth of information. This paper presents recent progress in the modelling of SNRs, particularly by the means of numerical simulations, and with a focus on three-dimensional aspects. In the first part we will consider SNRs as producers of cosmic rays (CRs). If SNRs are accelerators efficient enough to power the Galactic component of CRs, this must have a visible impact on their dynamics, and therefore on the thermal emission from the plasma, as well as on their non-thermal emission. In the second part we will consider SNRs as probes of the explosion mechanism. The time has come to connect multi-dimensional simulations of SNe and simulations of SNRs, opening the possibility to study the explosion mechanism via the dynamics and morphology of SNRs.

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arXiv2019

Matter Mixing in Aspherical Core-collapse Supernovae: Three-dimensional Simulations with Single Star and Binary Merger Progenitor Models for SN 1987A

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 merger progenitor model and with an asymmetric bipolar-like explosion, which invokes a jetlike explosion, best reproduces constraints on the mass of high velocity $^{56}$Ni, as inferred from the observed [Fe II] line profiles. The advantage of the binary merger progenitor model for the matter mixing is the flat and less extended $ρ\,r^3$ profile of the C+O core and the helium layer, which may be characterized by the small helium core mass. From the best explosion model, the direction of the bipolar explosion axis (the strongest explosion direction), the neutron star (NS) kick velocity, and its direction are predicted. Other related implications and future prospects are also given.

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arXiv2019

From the supernova to the supernova remnant: the three-dimensional imprint of a thermonuclear explosion

Recent progress in the three-dimensional modeling of supernovae (SN) has shown the importance of asymmetries for the explosion. This calls for a reconsideration of the modeling of the subsequent phase, the supernova remnant (SNR), which has commonly relied on simplified ejecta models. In this paper we bridge SN and SNR studies by using the output of a SN simulation as the input of a SNR simulation carried on until 500~yr. We consider the case of a thermonuclear explosion of a carbon-oxygen white dwarf star as a model for a Type Ia SN; specifically we use the N100 delayed detonation model of Seitenzahl et al 2013. In order to analyze the morphology of the SNR, we locate the three discontinuities that delineate the shell of shocked matter: the forward shock, the contact discontinuity, and the reverse shock, and we decompose their radial variations as a function of angular scale and time. Assuming a uniform ambient medium, we find that the impact of the SN on the SNR may still be visible after hundreds of years. Previous 3D simulations aiming at reproducing Tycho's SNR, that started out from spherically symmetric initial conditions, failed to reproduce structures at the largest angular scales observed in X-rays. Our new simulations strongly suggest that the missing ingredient was the initial asymmetries from the SN itself. With this work we establish a way of assessing the viability of SN models based on the resulting morphology of the SNR.

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arXiv2018

Engaging the Public with Supernova and Supernova Remnant Research Using Virtual Reality

On 21 April 2018, the citizens of Wako, Japan, interacted in a novel way with research being carried out at the Astrophysical Big Bang Laboratory (ABBL) at RIKEN. They were able to explore a model of a supernova and its remnant in an immersive three-dimentional format by using virtual reality (VR) technology. In this article, we explain how this experience was developed and delivered to the public, providing practical tips for and reflecting on the successful organisation of an event of this kind.

astro-ph.IM↗

arXiv2016

3D simulations of young core-collapse supernova remnants undergoing efficient particle acceleration

Within our Galaxy, supernova remnants are believed to be the major sources of cosmic rays up to the "knee". However important questions remain regarding the share of the hadronic and leptonic components, and the fraction of the supernova energy channelled into these components. We address such question by the means of numerical simulations that combine a hydrodynamic treatment of the shock wave with a kinetic treatment of particle acceleration. Performing 3D simulations allows us to produce synthetic projected maps and spectra of the thermal and non-thermal emission, that can be compared with multi-wavelength observations (in radio, X-rays, and gamma-rays). Supernovae come in different types, and although their energy budget is of the same order, their remnants have different properties, and so may contribute in different ways to the pool of Galactic cosmic-rays. Our first simulations were focused on thermonuclear supernovae, like Tycho's SNR, that usually occur in a mostly undisturbed medium. Here we present our 3D simulations of core-collapse supernovae, like the Cas A SNR, that occur in a more complex medium bearing the imprint of the wind of the progenitor star.

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arXiv2016

3D visualization of astronomy data cubes using immersive displays

We report on an exploratory project aimed at performing immersive 3D visualization of astronomical data, starting with spectral-line radio data cubes from galaxies. This work is done as a collaboration between the Department of Physics and Astronomy and the Department of Computer Science at the University of Manitoba. We are building our prototype using the 3D engine Unity, because of its ease of use for integration with advanced displays such as a CAVE environment, a zSpace tabletop, or virtual reality headsets. We address general issues regarding 3D visualization, such as: load and convert astronomy data, perform volume rendering on the GPU, and produce physically meaningful visualizations using principles of visual literacy. We discuss some challenges to be met when designing a user interface that allows us to take advantage of this new way of exploring data. We hope to lay the foundations for an innovative framework useful for all astronomers who use spectral line data cubes, and encourage interested parties to join our efforts. This pilot project addresses the challenges presented by frontier astronomy experiments, such as the Square Kilometre Array and its precursors.

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