Structure Of Ejecta Research Articles

Simulations of Early Kilonova Emission from Neutron Star Mergers

Abstract We present radiative transfer simulations for blue kilonovae hours after neutron star (NS) mergers by performing detailed opacity calculations for the first time. We calculate atomic structures and opacities of highly ionized elements (up to the 10th ionization) with atomic number Z = 20–56. We find that the bound–bound transitions of heavy elements are the dominant source of the opacities in the early phase (t < 1 day after the merger) and that the ions with a half-closed electron shell provide the highest contributions. The Planck mean opacity for lanthanide-free ejecta (with electron fraction of Y e = 0.30–0.40) can only reach around at t = 0.1 days, whereas that increases up to at t = 1 day. The spherical ejecta model with an ejecta mass of M ej = 0.05 M ⊙ gives the bolometric luminosity of at t ∼ 0.1 days. We confirm that the existing bolometric and multicolor data of GW170817 can be naturally explained by the purely radioactive model. The expected early UV signals reach 20.5 mag at t ∼ 4.3 hr for sources even at 200 Mpc, which is detectable by the facilities such as Swift and the Ultraviolet Transient Astronomy Satellite (ULTRASAT). The early-phase luminosity is sensitive to the structure of the outer ejecta, as also pointed out by Kasen et al. Therefore, the early UV observations give strong constraints on the structure of the outer ejecta and the presence of a heating source besides r-process nuclei.

Comparing Moment-based and Monte Carlo Methods of Radiation Transport Modeling for Type II-Plateau Supernova Light Curves

Abstract Time-dependent electromagnetic signatures from core-collapse supernovae are the result of detailed transport of the shock-deposited and radioactively powered radiation through the stellar ejecta. Due to the complexity of the underlying radiative processes, considerable approximations are made to simplify key aspects of the radiation transport problem. We present a systematic comparison of the moment-based radiation hydrodynamical code STELLA and the Monte Carlo radiation transport code Sedona in the 1D modeling of Type II-Plateau supernovae. Based on explosion models generated from the Modules for Experiments in Stellar Astrophysics instrument, we find remarkable agreements in the modeled light curves and the ejecta structure thermal evolution, affirming the fidelity of both radiation transport modeling approaches. The radiative moments computed directly by the Monte Carlo scheme in Sedona also verify the accuracy of the moment-based scheme. We find that the coarse resolutions of the opacity tables and the numerical approximations in STELLA have an insignificant impact on the resulting bolometric light curves, making it an efficient tool for the specific task of optical light-curve modeling.

Three-dimensional Kinematic Reconstruction of the Optically Emitting, High-velocity, Oxygen-rich Ejecta of Supernova Remnant N132D

Abstract We present a three-dimensional kinematic reconstruction of the optically emitting, oxygen-rich ejecta of supernova remnant N132D in the Large Magellanic Cloud (LMC). Data were obtained with the 6.5 m Magellan telescope in combination with the IMACS+GISMO instrument and survey [O iii] λλ4959, 5007 line emission in a ∼3′ × 3′ region centered on N132D. The spatial and spectral resolutions of our data enable detailed examination of the optical ejecta structure. The majority of N132D’s optically bright oxygen ejecta are arranged in a torus-like geometry tilted approximately 28° with respect to the plane of the sky. The torus has a radius of 4.4 pc (D LMC/50 kpc), exhibits a blueshifted radial velocity asymmetry of −3000 to +2300 km s−1, and has a conspicuous break in its circumference. Assuming homologous expansion from the geometric center of O-rich filaments, the average expansion velocity of 1745 km s−1 translates to an age since explosion of 2450 ± 195 yr. A faint, spatially separated “runaway knot” (RK) with total space velocity of 3650 km s−1 is nearly perpendicular to the torus plane and coincident with X-ray emission that is substantially enhanced in Si relative to the LMC and N132D’s bulk ejecta. These kinematic and chemical signatures suggest that the RK may have had its origin deep within the progenitor star. Overall, the main-shell morphology and high-velocity, Si-enriched components of N132D have remarkable similarity with those of Cassiopeia A, which was the result of a Type IIb supernova explosion. Our results underscore the need for further observations and simulations that can robustly reconcile whether the observed morphology is dominated by explosion dynamics or shaped by interaction with the environment.

Cosmic noise absorption signature of particle precipitation during interplanetary coronal mass ejection sheaths and ejecta

Abstract. We study here energetic-electron (E>30 keV) precipitation using cosmic noise absorption (CNA) during the sheath and ejecta structures of 61 interplanetary coronal mass ejections (ICMEs) observed in the near-Earth solar wind between 1997 and 2012. The data come from the Finnish riometer (relative ionospheric opacity meter) chain from stations extending from auroral (IVA, 65.2∘ N geomagnetic latitude; MLAT) to subauroral (JYV, 59.0∘ N MLAT) latitudes. We find that sheaths and ejecta lead frequently to enhanced CNA (>0.5 dB) both at auroral and subauroral latitudes, although the CNA magnitudes stay relatively low (medians around 1 dB). Due to their longer duration, ejecta typically lead to more sustained enhanced CNA periods (on average 6–7 h), but the sheaths and ejecta were found to be equally effective in inducing enhanced CNA when relative-occurrence frequency and CNA magnitude were considered. Only at the lowest-MLAT station, JYV, ejecta were more effective in causing enhanced CNA. Some clear trends of magnetic local time (MLT) and differences between the ejecta and sheaths were found. The occurrence frequency and magnitude of CNA activity was lowest close to midnight, while it peaked for the sheaths in the morning and afternoon/evening sectors and for the ejecta in the morning and noon sectors. These differences may reflect differences in typical MLT distributions of wave modes that precipitate substorm-injected and trapped radiation belt electrons during the sheaths and ejecta. Our study also emphasizes the importance of substorms and magnetospheric ultra-low-frequency (ULF) waves for enhanced CNA.

Properties of gamma-ray decay lines in 3D core-collapse supernova models, with application to SN 1987A and Cas A

ABSTRACT Comparison of theoretical line profiles to observations provides important tests for supernova explosion models. We study the shapes of radioactive decay lines predicted by current 3D core-collapse explosion simulations, and compare these to observations of SN 1987A and Cas A. Both the widths and shifts of decay lines vary by several thousand kilometres per second depending on viewing angle. The line profiles can be complex with multiple peaks. By combining observational constraints from 56Co decay lines, 44Ti decay lines, and Fe IR lines, we delineate a picture of the morphology of the explosive burning ashes in SN 1987A. For MZAMS = 15−20 M⊙ progenitors exploding with ∼1.5 × 1051 erg, ejecta structures suitable to reproduce the observations involve a bulk asymmetry of the 56Ni of at least ∼400 km s−1 and a bulk velocity of at least 1500 km s−1. By adding constraints to reproduce the UVOIR bolometric light curve of SN 1987A up to 600 d, an ejecta mass around 14 M⊙ is favoured. We also investigate whether observed decay lines can constrain the neutron star (NS) kick velocity. The model grid provides a constraint VNS > Vredshift, and applying this to SN 1987A gives a NS kick of at least 500 km s−1. For Cas A, our single model provides a satisfactory fit to the NuSTAR observations and reinforces the result that current neutrino-driven core-collapse SN models achieve enough bulk asymmetry in the explosive burning material. Finally, we investigate the internal gamma-ray field and energy deposition, and compare the 3D models to 1D approximations.

The ambiguous transient ASASSN-17hx

Aims. Some transients, although classified as novae based on their maximum and early decline optical spectra, cast doubts on their true nature, and raise the question of whether nova impostors might exist. Methods. We monitored a candidate nova that displayed a distinctly unusual light curve at maximum and early decline through optical spectroscopy (3000–10 000 Å, 500 < R < 100 000) complemented with Swift UV and AAVSO optical photometry. We use the spectral line series to characterize the ejecta dynamics, structure, and mass. Results. We find that the ejecta are in free ballistic expansion and have a typical classical nova structure. However, their derived mass is at least an order of magnitude higher than the typical ejecta masses obtained for classical novae. Specifically, we find Mej ≃9 × 10−3 M⊙ independent of the distance for a filling factor ε = 1. By constraining the distance we derived ε in the range 0.08–0.10, giving a mass 7 × 10−4 ≲ Mej ≲ 9 × 10−4 M⊙. The nebular spectrum, characterized by unusually strong coronal emission lines, confines the ionizing source energy to the range 20–250 eV, possibly peaking in the range 75–100 or 75–150 eV. Conclusions. We link this source to other slow novae that show similar behavior, and we suggest that they might form a distinct physical subgroup. The sources may result from a classical nova explosion occurring on a very low-mass white dwarf or they may be impostors for an entirely different type of transient.

A Nucleosynthetic Origin for the Southwestern Fe-rich Structure in Kepler’s Supernova Remnant

Abstract Chandra X-ray observations of Kepler’s supernova remnant indicate the existence of a high-speed Fe-rich ejecta structure in the southwestern region. We report strong K-shell emission from Fe-peak elements (Cr, Mn, Fe, Ni), as well as Ca, in this Fe-rich structure, implying that those elements could be produced in the inner area of the exploding white dwarf. We found Ca/Fe, Cr/Fe, Mn/Fe, and Ni/Fe mass ratios of 1.0%–4.1%, 1.0%–4.6%, 1%–11%, and 2%–30%, respectively. In order to constrain the burning regime that could produce this structure, we compared these observed mass ratios with those in 18 one-dimensional Type Ia nucleosynthesis models (including both near-M Ch and sub-M Ch explosion models). The observed mass ratios agree well with those around the middle layer of incomplete Si burning in Type Ia nucleosynthesis models with a peak temperature of ∼(5.0–5.3) × 109 K and a high metallicity, Z > 0.0225. Based on our results, we infer the necessity for some mechanism to produce protruding Fe-rich clumps dominated by incomplete Si-burning products during the explosion. We also discuss the future perspectives of X-ray observations of Fe-rich structures in other Type Ia supernova remnants.

Supernova Ejecta Interacting with a Circumstellar Disk. I. Two-dimensional Radiation-hydrodynamic Simulations

Abstract We perform a series of two-dimensional radiation-hydrodynamic simulations of the collision between supernova ejecta and circumstellar media (CSMs). The hydrodynamic interaction of a fast flow and the surrounding media efficiently dissipates the kinetic energy of the fast flow and is considered as a dominant energy source for a specific class of core-collapse supernovae. Despite some observational evidence for aspherical ejecta and/or CSM structure, multidimensional effects in the ejecta–CSM interaction are relatively unexplored. Our numerical simulations equipped with an adaptive mesh refinement technique successfully reproduce hydrodynamic instabilities developing around the ejecta–CSM interface. We also investigate effects of disklike CSMs on the dynamical evolution of supernova ejecta and bolometric light curves. We find that emission powered by ejecta–disk interaction exhibits significant viewing angle dependence. For a line of sight close to the symmetry axis, the observer directly sees the supernova ejecta, leading to a short brightening timescale. For an observer seeing the emission through the CSM disk, thermal photons diffuse throughout the CSM, and thus the light curve is severely smeared out.

E0102-VR: Exploring the scientific potential of Virtual Reality for observational astrophysics

Virtual Reality (VR) technology has been subject to a rapid democratization in recent years, driven in large by the entertainment industry, and epitomized by the emergence of consumer-grade, plug-and-play, room-scale VR devices. To explore the scientific potential of this technology for the field of observational astrophysics, we have created an experimental VR application: E0102-VR. The specific scientific goal of this application is to facilitate the characterization of the 3D structure of the oxygen-rich ejecta in the young supernova remnant 1E 0102.2-7219 in the Small Magellanic Cloud. Using E0102-VR, we measure the physical size of two large cavities in the system, including a (7.0$\pm$0.5) pc-long funnel structure on the far-side of the remnant. The E0102-VR application, albeit experimental, demonstrates the benefits of using human depth perception for a rapid and accurate characterization of complex 3D structures. Given the implementation costs (time-wise) of a dedicated VR application like E0102-VR, we conclude that the future of VR for scientific purposes in astrophysics most likely resides in the development of a robust, generic application dedicated to the exploration and visualization of 3D observational datasets, akin to a ``ds9-VR''.

High-energy X-ray radiography investigation on the ejecta physics of laser shock-loaded tin

This study is devoted to the high-energy X-ray radiography investigation on the ejecta physics of laser shock-loaded tin. The ejecta were generated via laser shock loaded tin under sequential shock-breakout pressures by high-power nanosecond lasers. A high-energy X-ray (50∼200keV) source was created to radiograph the high dense ejecta. Due to its strong penetration, high-quality radiograph images were obtained with detailed inner information and topology structure of ejecta. The areal density distribution and total mass of ejecta were further inferred. It was found that the ejecta from laser shock-loaded tin under sequential pressures show obvious difference in density distribution between the samples in a solid state and in a melt-on-release state. In addition, the total mass of ejecta was demonstrated to increase sharply when the breakout pressure is larger than the onset of melt-on-release for tin. Such increase inferred a solid-liquid phase transition of ejecta production mechanism.

Genus Statistic Applied to the X-Ray Remnant of SN 1572: Clues to the Clumpy Ejecta Structure of Type Ia Supernovae

Abstract Clumpy structures are a common feature in X-ray images of young Type Ia supernova remnants (SNRs). Although the precise origin of such clumps remains unclear, there are three generic possibilities: clumpiness imposed during the explosion, hydrodynamic instabilities that act during the remnant’s evolution, and preexisting structures in the ambient medium. In this article we focus on discriminating between clumping distributions that arise from the explosion and those from the remnant’s evolution using existing 3D hydrodynamical simulations. We utilize the genus statistic for this discrimination, applying it to the simulations and to Chandra X-ray observations of the well-known SN Ia remnant of SN 1572 (Tycho’s SNR). The genus curve of Tycho’s SNR strongly indicates a skewed non-Gaussian distribution of the ejecta clumps and is similar to the genus curve for the simulation with initially clumped ejecta. In contrast, the simulation of perfectly smooth ejecta where clumping arises from the action of hydrodynamic instabilities produced a genus curve that is similar to a random Gaussian field, but disagrees strongly with the genus curve of the observed image. Our results support a scenario in which the observed structure of SN Ia remnants arises from initial clumpiness in the explosion.

Constraining Type Ia supernova asymmetry with the gamma-ray escape time-scale

We calculate the effects of an asymmetric $^{56}\mathrm{Ni}$ distribution in Type Ia supernova (SN Ia) ejecta on the gamma-ray escape timescale ($t_0$) that characterizes the late light curve ($>40$ days after peak) and find the effect is modest compared to other possible variations in ejecta structure. We parameterize asymmetry in the $^{56}\mathrm{Ni}$ distribution and calculate $t_0$ for a grid of SN ejecta models spanning a large volume of the asymmetry parameter space. The models have spherical density profiles while the $^{56}\mathrm{Ni}$ distribution in them has various levels of asymmetry. By placing constraints based on the observational measurement of $t_0$ and other general properties of SN Ia ejecta, we find the range of allowed asymmetry in the $^{56}\mathrm{Ni}$ distribution. Considering these constraints we find that some level of asymmetry in the distribution is not ruled out. However, models with a single ejecta mass and varying $^{56}\mathrm{Ni}$ distributions cannot explain the full range of observed $t_0$ values. This strengthens the claim that both Chandrasekhar mass and sub-Chandrasekhar mass explosions are required to explain the diversity of SN Ia observations.

Ionization age of iron ejecta in the Galactic Type Ia supernova remnant G306.3−0.9

Abstract We present a 190 ks observation of the Galactic supernova remnant (SNR) G306.3−0.9 with Suzaku. To study ejecta properties of this possible Type Ia SNR, the absolute energy-scale at the Fe-K band was calibrated to a level of uncertainty less than 10 eV by a cross-calibration with the Hitomi microcalorimeter using the Perseus cluster spectra. This enabled us for the first time to determine the ionization state of the Fe Kα line of this SNR accurately. The ionization time-scale (τ) of the Fe ejecta was measured to be log10τ (cm−3 s) $= 10.24\, \pm \, 0.03$, significantly smaller than previous measurements. Marginally detected Kα lines of Cr and Mn have ionization time-scales consistent with that of Fe. The global spectrum was well-fitted with shocked interstellar matter (ISM) and at least two ejecta components with different ionization time-scales for Fe and intermediate mass elements (IME) such as S and Ar. One plausible interpretation of the one-order-of-magnitude shorter time-scale of Fe than that of IME ($\log _{10} \tau = 11.17\, \pm \, 0.07$) is a chemically stratified structure of ejecta. By comparing the X-ray absorption column to the H i distribution decomposed along the line of sight, we refined the distance to ∼20 kpc. The large ISM-to-ejecta shocked mass ratio of ∼100 and dynamical time-scale of ∼6 kyr place the SNR in the late Sedov phase. These properties are consistent with a stratified ejecta structure that has survived the mixing processes expected in an evolved SNR.

Evolution of the Progenitors of SNe 1993J and 2011dh Revealed through Late-time Radio and X-Ray Studies

Abstract We perform hydrodynamical simulations of the interaction between supernova (SN) ejecta and circumstellar medium (CSM) for SN 1993J and SN 2011dh, and calculate the radio and X-ray emissions expected from the shocked gas at late epochs (t). Considering the ejecta structure from multi-group radiation hydrodynamics simulation, we find that the observed rapid drop in radio and X-ray light curves of SN 1993J at t > 3000 days may be due to a change in the mass-loss rate ( ) ∼6500 yr prior to the explosion of the SN. The exact epoch scales inversely with the assumed wind velocity of v w = 10 . The progenitor of this SN very likely belonged to a binary system, where, during its evolution, the primary had transferred material to the secondary. It is argued in this paper that the change in can happen because of a change in the mass accretion efficiency (η) of the companion star. It is possible that before ∼6500 (v w/10 )−1 yr prior to the explosion, η was high, and thus the CSM was tenuous, which causes the late-time downturn in fluxes. In the case of SN 2011dh, the late-time evolution is found to be consistent with a wind medium with /v w = 4 × 10−6 /10 . It is difficult from our analysis to predict whether the progenitor of this SN had a binary companion; however, if future observations show a similar decrease in radio and X-ray fluxes, then this would give strong support to a scenario where both SNe had undergone a similar kind of binary evolution before explosion.

Optical spectroscopic and polarization properties of 2011 outburst of the recurrent nova T Pyxidis

Aims. We aim to study the spectroscopic and ionized structural evolution of T Pyx during its 2011 outburst, and also study the variation in degree of polarization during its early phase. Methods. Optical spectroscopic data of this system obtained from day 1.28–2415.62 since discovery, and optical, broadband imaging polarimetric observations obtained from day 1.36–29.33 during the early phases of the outburst were used in the study. The physical conditions and the geometry of the ionized structure of the nova ejecta was modelled for a few epochs using the photo-ionization code, CLOUDY in 1D and pyCloudy in 3D. Results. The spectral evolution of the nova ejecta during its 2011 outburst is similar to that of the previous outbursts. The variation in the line profiles is seen very clearly in the early stages due to good coverage during this period. The line profiles vary from P Cygni (narrower, deeper, and sharper) to emission profiles that are broader and structured, which later become narrower and sharper in the late post-outburst phase. The average ejected mass is estimated to be 7.03 × 10−6 M⊙. The ionized structure of the ejecta is found to be a bipolar conical structure with equatorial rings, with a low inclination angle of 14.75 ° ±0.65°.

Discovery of a jet-like structure with overionized plasma in the SNR IC 443

Context. IC 443 is a supernova remnant (SNR) located in a quite complex environment since it interacts with nearby clouds. Indications for the presence of overionized plasma have been found though the possible physical causes of overionization are still debated. Moreover, because of its peculiar position and proper motion, it is not clear if the pulsar wind nebula (PWN) within the remnant is the relic of the IC 443 progenitor star or just a rambling one seen in projection on the remnant. Aims. Here we address the study of IC 443 plasma in order to clarify the relationship PWN-remnant, the presence of overionization and the origin of the latter. Methods. We analyzed two XMM-Newton observations producing background-subtracted, vignetting-corrected and mosaicked images in two different energy bands and we performed a spatially resolved spectral analysis of the X-ray emission. Results. We identified an elongated (jet-like) structure with Mg-rich plasma in overionization. The head of the jet is interacting with a molecular cloud and the jet is aligned with the position of the PWN at the instant of the supernova explosion. Interestingly, the direction of the jet of ejecta is somehow consistent with the direction of the PWN jet. Conclusions. Our discovery of a jet of ejecta in IC 443 enlarge the sample of core-collapse SNRs with collimated ejecta structures. IC 443’s jet is the first one which shows overionized plasma, possibly associated with the adiabatic expansion of ejecta. The match between the jet’s direction and the original position of the PWN strongly supports the association between the neutron star and IC 443.

Early gray dust formation in the type IIn SN 2005ip

The physical characteristics of dust formed in supernovae is poorly known. In this paper, we investigate the extinction properties of dust formed in the type IIn SN 2005ip. The observed light curves of SN 2005ip all exhibit a sudden drop around 50 days after discovery. This has been attributed to dust formation in the dense circumstellar medium. We modeled the intrinsic light curves in six optical bands, adopting a theoretical model for the luminosity evolution of supernovae interacting with their circumstellar material. From the difference between the observed and intrinsic light curves, we calculated extinction curves as a function of time. The total-to-selective extinction ratio, RV, was determined from the extinction in the B and V bands. The resulting extinction, AV , increases monotonically up to about 1 mag, 150 days after discovery. The inferred RV value also increases slightly with time, but appears constant in the range 4.5–8, beyond 100 days after discovery. The analysis confirms that dust is likely formed in SN 2005ip, starting about two months after explosion. The high value of RV, that is, gray dust, suggests dust properties different from the Milky Way. While this result hinges on the assumed theoretical intrinsic light curve evolution, it is encouraging that the fitted light curves are as expected for standard ejecta and circumstellar medium density structures.

Spectral Sequences of Type Ia Supernovae. I. Connecting Normal and Subluminous SNe Ia and the Presence of Unburned Carbon

Abstract Type Ia supernovae (SNe Ia) are generally agreed to arise from thermonuclear explosions of carbon–oxygen white dwarfs. The actual path to explosion, however, remains elusive, with numerous plausible parent systems and explosion mechanisms suggested. Observationally, SNe Ia have multiple subclasses, distinguished by their light curves and spectra. This raises the question of whether these indicate that multiple mechanisms occur in nature or that explosions have a large but continuous range of physical properties. We revisit the idea that normal and 91bg-like SNe can be understood as part of a spectral sequence in which changes in temperature dominate. Specifically, we find that a single ejecta structure is sufficient to provide reasonable fits of both the normal SN Ia SN 2011fe and the 91bg-like SN 2005bl, provided that the luminosity and thus temperature of the ejecta are adjusted appropriately. This suggests that the outer layers of the ejecta are similar, thus providing some support for a common explosion mechanism. Our spectral sequence also helps to shed light on the conditions under which carbon can be detected in premaximum SN Ia spectra—we find that emission from iron can “fill in” the carbon trough in cool SNe Ia. This may indicate that the outer layers of the ejecta of events in which carbon is detected are relatively metal-poor compared to events in which carbon is not detected.

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

A small group of the newly discovered superluminous supernovae show broad and slowly evolving light curves. Here we present extensive observational data for the slow-evolving superluminous supernova LSQ14an, which brings this group of transients to four in total in the low redshift Universe (z$<$0.2; SN 2007bi, PTF12dam, SN 2015bn). We particularly focus on the optical and near-infrared evolution during the period from 50 days up to 400 days from peak, showing that they are all fairly similar in their light curve and spectral evolution. LSQ14an shows broad, blue-shifted [O III] $\lambda\lambda$4959, 5007 lines, as well as a blue-shifted [O II] $\lambda\lambda$7320, 7330 and [Ca II] $\lambda\lambda$7291, 7323. Furthermore, the sample of these four objects shows common features. Semi-forbidden and forbidden emission lines appear surprisingly early at 50-70 days and remain visible with almost no variation up to 400 days. The spectra remain blue out to 400 days. There are small, but discernible light curve fluctuations in all of them. The light curve of each shows a faster decline than $^{56}$Co after 150 days and it further steepens after 300 days. We also expand our analysis presenting X-ray limits for LSQ14an and SN2015bn and discuss their diagnostic power in interpreting their common features. These features are quite distinct from the faster evolving superluminous supernovae and are not easily explained in terms of only a variation in ejecta mass. While a central engine is still the most likely luminosity source, it appears that the ejecta structure is complex, with multiple emitting zones and at least some interaction between the expanding ejecta and surrounding material.

Bridging the gap between supernovae and their remnants through multi-dimensional hydrodynamic modeling

AbstractSupernova remnants (SNRs) are diffuse extended sources characterized by a complex morphology and a non-uniform distribution of ejecta. Such a morphology reflects pristine structures and features of the progenitor supernova (SN) and the early interaction of the SN blast wave with the inhomogeneous circumstellar medium (CSM). Deciphering the observations of SNRs might open the possibility to investigate the physical properties of both the interacting ejecta and the shocked CSM. This requires accurate numerical models which describe the evolution from the SN explosion to the remnant development and which connect the emission properties of the remnants to the progenitor SNe. Here we show how multi-dimensional SN-SNR hydrodynamic models have been very effective in deciphering observations of SNR Cassiopeia A and SN 1987A, thus unveiling the structure of ejecta in the immediate aftermath of the SN explosion and constraining the 3D pre-supernova structure and geometry of the environment surrounding the progenitor SN.