We consider sputtering of dust grains, believed to be formed in cooling supernovae ejecta, under the influence of reverse shocks. In the regime of self-similar evolution of reverse shocks, we can follow the evolution of ejecta density and temperature analytically as a function of time in different parts of the ejecta, and calculate the sputtering rate of graphite and silicate grains embedded in the ejecta as they encounter the reverse shock. Through analytic (1D) calculations, we find that a fraction of dust mass ($ 1\hbox{--}20$% for silicates and %$\le 5$% for graphites) can be sputtered by reverse shocks, the fraction varying with the grain size distribution and the steepness of the density profile of the ejecta mass. It is expected that many more grains will get sputtered in the region between the forward and reverse shocks, so that our analytical results provide a lower limit to the destroyed fraction of dust mass.
We present first results from an extensive survey of Magellanic Clouds supernova remnants (SNRs) with the Spitzer Space Telescope. We describe IRAC and MIPS imaging observations at 3.6, 4.5, 5.8, 8, 24, and 70 microns of four Balmer-dominated Type Ia SNRs in the Large Magellanic Cloud (LMC): DEM L71 (0505-67.9), 0509--67.5, 0519--69.0, and 0548-70.4. None was detected in the four short-wavelength IRAC bands, but all four were clearly imaged at 24 microns, and two at 70 microns. A comparison of these images to Chandra broadband X-ray images shows a clear association with the blast wave, and not…
We present new mechanisms by which the isotopic compositions of X-type grains of presolar SiC are altered by reverse shocks in Type II supernovae. We address three epochs of reverse shocks: pressure wave from the H envelope near t = 10$^6$s; reverse shock from the presupernova wind near 10$^8-10^9$s; reverse shock from the ISM near 10$^{10}$s. Using 1-D hydrodynamics we show that the first creates a dense shell of Si and C atoms near 10$^6$s in which the SiC surely condenses. The second reverse shock causes precondensed grains to move rapidly forward through decelerated gas of different isotop…
We report observations with the MIPS instrument aboard the {\it Spitzer Space Telescope} (SST) of four supernova remnants (SNRs) believed to be the result of core-collapse SNe: N132D (0525-69.6), N49B (0525-66.0), N23 (0506-68.0), and 0453-68.5. All four of these SNRs were detected in whole at 24 $μ$m and in part at 70 $μ$m. Comparisons with {\it Chandra} broadband X-ray images show an association of infrared (IR) emission with the blast wave. We attribute the observed IR emission to dust that has been collisionally heated by electrons and ions in the hot, X-ray emitting plasma, with grain siz…
Without amplification, magnetic fields in expanding ejecta of young supernova remnants (SNRs) will be orders of magnitude below those required to shock accelerate thermal electrons, or ions, to relativistic energies or to produce radio synchrotron emission at the reverse shock. The reported observations of such emission give support to the idea that diffusive shock acceleration (DSA) can amplify magnetic fields by large factors. Furthermore, the uncertain character of the amplification process leaves open the possibility that ejecta fields, while large enough to support radio emission and DSA,…
Using Chandra X-ray, Spitzer mid-IR, and 1.5 GHz radio data, we examine the spatial structure of SNR 3C391. The X-ray surface brightness is generally anti-correlative with the IR and radio brightness. The multiband data clearly exhibit a heart-shaped morphology and show the multi-shell structure of the remnant. A thin brace-like shell on the south detected at 24 um is projected outside the radio border and confines the southern faint X-ray emission. The leading 24 um knot on the SE boundary appears to be partly surrounded by soft X-ray emitting gas. The mid-IR emission is dominated by the cont…
A spherically symmetric model is presented for the interaction of a pulsar wind with the associated supernova remnant. This results in a pulsar wind nebula whose evolution is coupled to the evolution of the surrounding supernova remnant. This evolution can be divided in three stages. The first stage is characterised by a supersonic expansion of the pulsar wind nebula into the freely expanding ejecta of the progenitor star. In the next stage the pulsar wind nebula is not steady; the pulsar wind nebula oscillates between contraction and expansion due to interaction with the reverse shock of the …
We report the localization of the forward and reversed shock fronts in the young supernova remnant Cas-A using X-ray data obtained with the Chandra Observatory. High resolution X-ray maps resolve a previously unseen X-ray feature encompassing the extremity of the remnant. This feature consists of thin, tangential wisps of emission bordering the outer edge of the thermal X-ray and radio remnant, forming a circular rim, approx. 2.7 in radius. Radio images show a sharp rise in brightness at this X-ray rim, along with a large jump in the synchrotron polarization angle. These characteristics sugges…
The young oxygen-rich supernova remnant E0102-72 in the Small Magellanic Cloud has been observed with the High Energy Transmission Grating Spectrometer of Chandra. The high resolution X-ray spectrum reveals images of the remnant in the light of individual emission lines of oxygen, neon, magnesium and silicon. The peak emission region for hydrogen-like ions lies at larger radial distance from the SNR center than the corresponding helium-like ions, suggesting passage of the ejecta through the "reverse shock". We examine models which test this interpretation, and we discuss the implications.
This is the second paper (the first was astro-ph/9704267) of a series analysing the Galactic Cosmic Ray (GCR) composition and origin. In this we present a quantitative model of GCR origin and acceleration based on the acceleration of a mixture of interstellar and/or circumstellar gas and dust by supernova remnant blast waves. We present results from a nonlinear shock model which includes (i) the direct acceleration of interstellar gas-phase ions, (ii) a simplified model for the direct acceleration of weakly charged dust grains to energies of order 100keV/amu simultaneously with the gas ions, (…
We report the discovery of pulsed X-ray emission from the compact object CXOU J112439.1-591620 within the Galactic supernova remnant G292.0+1.8 using the High Resolution Camera on the Chandra X-Ray Observatory. The X-ray period is consistent with the extrapolation of the radio period and spindown rate of PSR J1124-5916. The X-ray pulse is single peaked and broad. There is no optical counterpart to a limit of M_V ~ 26. The pressure in the pulsar wind nebula is considerably less than that in the reverse-shock-heated ejecta and circumstellar medium, indicating that the reverse shock has not yet b…
The young SNR Cassiopeia A was imaged with WFPC-2 through four filters selected to capture the complete velocity range of the remnant's main shell in several important emission lines. Primary lines detected were [O III] 4959,5007, [N II] 6583, [S II] 6716,6731 + [O II] 7319,7330 + [O I] 6300,6364, and [S III] 9069,9532. About 3/4th of the remnant's main shell was imaged in all four filters. Considerable detail is observed in the reverse-shocked ejecta with typical knot scale lengths of 0.2"-0.4" (1 - 2 x 10^16 cm). Both bright and faint emission features appear highly clumped. Large difference…
We examine the evolution of inhomogeneities (fragments) of supernova ejecta in compact supernova remnants by means of hydrodynamical modeling and simplified analytical calculations. Under the influence of intense post-shock cooling the fragments become strongly compressed as they traverse the hot shocked region between the reverse and outer shocks of the remnant. We find that the most likely outcome of the interaction of fragments with the reverse shock and the hot shocked region is their disruption resulting in generation of secondary fragments. Secondary fragments arriving at the thin and de…
We present the global distribution of fine structure infrared line emission in the Cassiopeia A supernova remnant using data from the Spitzer Space Telescope's Infrared Spectrograph. We identify emission from ejecta materials in the interior, prior to their encounter with the reverse shock, as well as from the post-shock bright ring. The global electron density increases by >~100 at the shock to ~10^4 cm^-3, providing evidence for strong radiative cooling. There is also a dramatic change in ionization state at the shock, with the fading of emission from low ionization interior species like [Si…
We employ hydrodynamic simulations to study the effects of high shock compression ratios, as expected for fast shocks with efficient particle acceleration, on the convective instability of driven waves in supernova remnants. We find that the instability itself does not depend significantly on the compression ratio, but because the width of the interaction region between the forward and reverse shocks can shrink significantly with increasing shock compression, we find that convective instabilities can reach all the way to the forward shock front if compression ratios are high enough.
We present a model of a pulsar wind nebula evolving inside its associated supernova remnant. The model uses a hydrodynamics code to simulate the evolution of this system when the pulsar has a high velocity. The simulation distinguishes four different stages of pulsar wind nebula evolution: the supersonic expansion stage, the reverse shock interaction stage, the subsonic expansion stage and ultimately the bow shock stage. The simulation bears out that, due to the high velocity of the pulsar, the position of the pulsar is off-centered with respect to its pulsar wind nebula, after the passage of …
We present two-dimensional high-resolution hydrodynamical simulations in spherical polar coordinates of a Type Ia supernova interacting with a constant density interstellar medium. The ejecta are assumed to be freely expanding with an exponential density profile. The interaction gives rise to a double-shocked structure susceptible to hydrodynamic instabilities. The Rayleigh-Taylor instability initially grows, but the Kelvin-Helmholtz instability takes over, producing vortex rings. The nonlinear instability initially evolves toward longer wavelengths and eventually fades away when the reverse s…
A new method to evaluate the dust-to-gas ratios in the Kepler SNR is presented. Dust emission in the infrared and bremsstrahlung are calculated consistently, considering that dust grains are collisionally heated by the gas throughout the front and downstream of both the expanding and the reverse shocks. The dust-to-gas ratios are determined by the ratio of the dust emission bump and bremsstrahlung in the infrared. A maximum dust mass < 0.16 Mo is calculated.
I review several topics in the structure of supernova remnants. Hydrodynamic instabilities in young remnants may give rise to the cellular structure that is sometimes observed, although structure in the ejecta might also play a role. The presence of ejecta close to the forward shock front of a young remnant can be the result of ejecta clumps or the dynamical effects of cosmic rays. Slower moving ejecta clumps can affect the outer shock structure of older remnants such as Vela. Young remnants typically show a circular structure, but often have a one-sided asymmetry; the likely reasons are an as…
We present the observation of the Tycho supernova remnant obtained with the EPIC and RGS instruments onboard the XMM-Newton satellite. We compare images and azimuthally averaged radial profiles in emission lines from different elements (silicon and iron) and different transition lines of iron (Fe L and Fe K). While the Fe XVII L line and Si XIII K line images are globally spatially coincident, the Fe K emission clearly peaks at a smaller radius, indicating a higher temperature toward the reverse shock. This is qualitatively the profile expected when the reverse shock, after travelling through …
We present Chandra ACIS X-ray observations of the Galactic supernova remnant Cassiopeia A taken in December 2007. Combining these data with previous archival Chandra observations taken in 2000, 2002, and 2004, we estimate the remnant's forward shock velocity at various points around the outermost shell to range between 4200 and 5200 +/- 500 km/s. Using these results together with previous analyses of Cas A's X-ray emission, we present a model for the evolution of Cas A and find that it's expansion is well fit by a rho_ej ~ r^{-(7-9)} ejecta profile running into a circumstellar wind. We further…
We investigate the evolution of dust that formed at Population III supernova (SN) explosions and its processing through the collisions with the reverse shocks resulting from the interaction of the SN ejecta with the ambient medium. In particular, we investigate the transport of the shocked dust within the SN remnant (SNR), and its effect on the chemical composition, the size distribution, and the total mass of dust surviving in SNR. We find that the evolution of the reverse shock, and hence its effect on the processing of the dust depends on the thickness of the envelope retained by the progen…
The High Energy Transmission Grating (HETG) Spectrometer aboard the Chandra X-Ray Observatory was used to observe E0102-72, a ~1000 year old, oxygen rich supernova in the Small Magellanic Cloud. The HETG disperses the image of the remnant into a spectrum of images in the light of individual X-ray emission lines. Doppler shifts in the strongest lines of oxygen and neon reveal bulk motions of up to 2000 km/sec with a complex morphology. Comparison of progressive ionization stages of magnesium, neon, oxygen and silicon provide new insights into the mechanism of the `reverse shock' that heats the …
We continue our analysis of the Galactic oxygen-rich supernova remnant (SNR) G292.0+1.8, which was observed with the {\it Chandra X-ray Observatory}. The high angular resolution {\it Chandra} data resolve metal-rich ejecta knots as well as the shocked circumstellar medium. X-ray emission from the ejecta material in G292.0+1.8 is dominated by highly ionized O, Ne and Mg. Measured abundance ratios suggest that this material was produced during the hydrostatic evolution of the massive progenitor star. In contrast to Cassiopeia A, there is little evidence for X-ray-emitting ejecta from explosive n…
We present Spitzer Space Telescope and Chandra X-ray Observatory observations of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the detected flux at 24 microns and hot gas parameters from fitting spectra from new, deep X-ray observations to constrain models of dust emission, obtaining a dust-to-gas mass ratio M_dust/M_gas ~0.001. We find that a two-component thermal model, nominally representing shocked swept-up interstellar or circumstellar material and reverse-shocked ejecta, adequately fits the X-ray spectrum, albeit with somewhat high implied densities for both compone…
The Crab Nebula is likely to be expanding into freely expanding supernova ejecta, although the energy in the ejecta may be less than is typical for a Type II supernova. Pulsar nebulae much younger than the Crab have not been found and could have different properties. The search for such nebulae through ultraviolet/optical line emission in core collapse supernovae, or through their X-ray emission (which could show strong absorption) is warranted. Neutron stars have now been found in many young supernova remnants. There is not a clear link between neutron star and remnant type, although there is…
We present 3.6 - 160 micron infrared images of Kepler's supernova remnant (SN1604) obtained with the IRAC and MIPS instruments on the Spitzer Space Telescope. We also present MIPS SED low resolution spectra in the 55 - 95 micron region. The observed emission in the MIPS 24 micron band shows the entire shell. Emission in the MIPS 70 micron and IRAC 8 micron bands is seen only from the brightest regions of 24 micron emission, which also correspond to the regions seen in optical Halpha images. Shorter wavelength IRAC images are increasingly dominated by stars, although faint filaments are discern…
(Abridged) We present a detailed radio study of the young supernova remnant (SNR) G292.0+1.8 and its associated pulsar PSR J1124-5916, using the Australia Telescope Compact Array at observing wavelengths of 20, 13 and 6 cm. We find that the radio morphology of the source consists of three main components: a polarized flat-spectrum central core coincident with the pulsar J1124-5916, a surrounding circular steep-spectrum plateau with sharp outer edges and, superimposed on the plateau, a series of radial filaments with spectra significantly flatter than their surroundings. HI absorption argues fo…
We investigate the evolution of dust formed in Population III supernovae (SNe) by considering its transport and processing by sputtering within the SN remnants (SNRs). We find that the fates of dust grains within SNRs heavily depend on their initial radii $a_{\rm ini}$. For Type II SNRs expanding into the ambient medium with density of $n_{\rm H,0} = 1$ cm$^{-3}$, grains of $a_{\rm ini} < 0.05$ $μ$m are detained in the shocked hot gas and are completely destroyed, while grains of $a_{\rm ini} > 0.2$ $μ$m are injected into the surrounding medium without being destroyed significantly. Grains wit…
The reverse shock of supernova remnant (SNR) 1987A emits in H-alpha and Ly-alpha, and comes in two flavors: surface and interior. The former is due to direct, impact excitation of hydrogen atoms crossing the shock, while the latter is the result of charge transfer reactions between these atoms and slower, post-shock ions. Interior and surface emission are analogous to the broad- and narrow-line components observed in Balmer-dominated SNRs. I summarize a formalism to derive line intensities and ratios in these SNRs, as well as a study of the transition zone in supernova shocks; I include an app…
We use two-dimensional hydrodynamical simulations to investigate the properties of dense ejecta clumps (bullets) in a core collapse supernova remnant, motivated by the observation of protrusions probably caused by clumps in the Vela supernova remnant. The ejecta, with an inner flat and an outer steep power law density distribution, were assumed to freely expand into an ambient medium with a constant density, $\sim 0.1$ H atoms cm$^{-3}$ for the case of Vela. At an age of $10^4$ yr, the reverse shock front is expected to have moved back to the center of the remnant. Ejecta clumps with an initia…
In the late 1960s the discovery of the Crab pulsar in its associated supernova remnant, launched a new field in supernova remnant research: the study of pulsar-driven or plerionic supernova remnants. In these type of remnants, the relativistic wind emitted by the pulsar, blows a pulsar wind nebula into the interior of its supernova remnant. Now, more then forty years after the discovery of the Crab pulsar, there are more then fifty plerionic supernova remnants known, due to the ever-increasing capacity of observational facilities. I will review our current understanding of the different evolut…
The presence of dust at high redshift requires efficient condensation of grains in SN ejecta, in accordance with current theoretical models. Yet, observations of the few well studied SNe and SN remnants imply condensation efficiencies which are about two orders of magnitude smaller. Motivated by this tension, we have (i) revisited the model of Todini & Ferrara (2001) for dust formation in the ejecta of core collapse SNe and (ii) followed, for the first time, the evolution of newly condensed grains from the time of formation to their survival - through the passage of the reverse shock - in the …
We have obtained a second epoch observation of the Cassiopeia A supernova remnant (SNR) with the Chandra X-ray Observatory to measure detailed X-ray proper motions for the first time. Both epoch observations are 50 ks exposures of the ACIS-S3 chip and they are separated by 2 years. Measurements of the thin X-ray continuum dominated filaments located around the edge of the remnant (that are identified with the forward shock) show expansion rates from 0.02%/yr to 0.33%/yr. Many of these filaments are therefore significantly decelerated. Their median value of 0.21%/yr is equal to the median expan…
The supernova remnants left behind by Type Ia supernovae provide an excellent opportunity for the study of these enigmatic objects. In a previous work, we showed that it is possible to use the X-ray spectra of young Type Ia supernova remnants to explore the physics of Type Ia supernovae and identify the relevant mechanism underlying these explosions. Our simulation technique is based on hydrodynamic and nonequilibrium ionization calculations of the interaction of a grid of Type Ia explosion models with the surrounding ambient medium, coupled to an X-ray spectral code. In this work we explore t…
We calculate the spallative production of light elements associated with the explosion of an isolated supernova in the interstellar medium, using a time-dependent model taking into account the dilution of the ejected enriched material and the adiabatic energy losses. We first derive the injection function of energetic particles (EPs) accelerated at both the forward and the reverse shock, as a function of time. Then we calculate the Be yields obtained in both cases and compare them to the value implied by the observational data for metal-poor stars in the halo of our Galaxy, using both O and Fe…
Pulsars, formed during supernova explosions, are known to be sources of relativistic magnetized winds whose interaction with the expanding supernova remnants (SNRs) gives rise to a pulsar wind nebula (PWN). We present spherically symmetric relativistic magnetohydrodynamics (RMHD) simulations of the interaction of a pulsar wind with the surrounding SNR, both in particle and magnetically dominated regimes. As shown by previous simulations, the evolution can be divided in three phases: free expansion, a transient phase characterized by the compression and reverberation of the reverse shock, and a…
We report on our analysis of the 1 Ms Chandra observation of the supernova remnant Cas A in order to localize, characterize and quantify its non-thermal X-ray emission. More specifically, we investigated whether the X-ray synchrotron emission from the inside of the remnant is from the outward shock, but projected toward the inner ring, or from the inner shell. We tackle this problem by employing a Lucy-Richardson deconvolution technique and measuring spectral indices in the 4.2-6 keV band. We show that most of the continuum emission is coming from an inner ring that coincides with the location…
We present a model of a pulsar-driven supernova remnant, by using a hydrodynamics code, which simulates the evolution of a pulsar wind nebula when the pulsar is moving at a high velocity through its expanding supernova remnant. The simulation shows four different stages of the pulsar wind nebula: the supersonic expansion stage, the reverse shock interaction stage, the subsonic expansion stage and ultimately the bow shock stage. Due to the high velocity of the pulsar, the position of the pulsar is located at the head of the pulsar wind bubble, after the passage of the reverse shock. The resulti…
Observations of the radio remnant of Supernova 1987A using the Australia Telescope Compact Array in the 12-mm band on 2003 July 31 (day 6002.7 after the explosion) give the first fully resolved radio image of the supernova remnant. The diffraction-limited image has a resolution of about 0.45 arcsec, a factor of two better than that of the 3-cm images previously obtained. There is excellent agreement between the 12-mm image and a contemporaneous super-resolved 3-cm image. Super-resolution of the 12-mm image gives a further factor of two improvement in resolution, to 0.25 arcsec, albeit with lim…
Spallative nucleosynthesis is thought to be the only process capable of producing significant amount of Beryllium (Be) in the universe. Therefore, both energetic particles (EPs) and nuclei to be spalled (most efficiently C, N and O nuclei in this case) are required, which indicates that supernovae (SNe) may be directly involved in the synthesis of the Be nuclei observed in the halo stars of the Galaxy. We apply current knowledge relating to supernova remnant (SNR) evolution and particle shock acceleration to calculate the total Be yield associated with a SN explosion in the interstellar medium…
We report the discovery of a new SNR in the \ros All-Sky-Survey data. The SNR has a nearly circular shape with a diameter of about 15 arcmin. The surface brightness is rather uniform over the remnant. The observed interstellar absorption suggests a distance of about 1.8$^{+1.4}_{-0.8}$ kpc. The X-ray emission appears to be of thermal origin with a plasma temperature of about 10$^7$ K. The Sedov model leads to an age of only 1800 years. We find no spectral evidence of non-thermal emission in the center of the remnant. The two most likely explanations for the centrally filled structure are evapo…
Radioactive isotopes such as 44Ti offer probably the most direct probe into nucleosynthesis environments in the interior of exploding stars, when the associated gamma-ray activities in the explosion remnant are detected and translated back to the isotopic abundances at the time of the explosion. In this paper, we assert that the procedure may not necessarily be straightforward, at least in the case of 44Ti, an orbital-electron capture decay isotope. Using the analytic model of McKee and Truelove (1995) for young supernova remnants, and assuming the existence of overdense 56Fe-dominated clumps …
We use low-dispersion spectra obtained at the Magellan Observatory to study the broad H-alpha emission from the reverse shock of the infant supernova remnant SNR1987A. These spectra demonstrate that the spatio-kinematic structure of the reverse shock can be distinguished from that of the circumstellar ring and hotspots, even at ground-based spatial resolution. We measure a total dereddened H-alpha flux of 1.99(pm0.22)e-13 ergs/s/cm2 at an epoch 18.00 years after outburst. At 50 kpc, the total reverse shock luminosity in H-alpha is roughly 15 Lsun, which implies a total flux of neutral hydrogen…
Recent discovery of the year-scale variability in the synchrotron X-ray emission of the supernova remnant (SNR) RX J1713.7-3946 has initiated our study of multi-epoch X-ray images and spectra of the young SNR Cassiopeia A based on the Chandra archive data taken in 2000, 2002, and 2004. We have found year-scale time variations in the X-ray intensity for a number of X-ray filaments or knots associated with the reverse-shocked regions. The X-ray spectra of the variable filaments are characterized by a featureless continuum, and described by a power law with a photon index within 1.9-2.3. The uppe…
We report on X-ray observations of the supernova remnant 0509-67.5 in the Large Magellanic Cloud with XMM-Newton X-ray observatory. We use the imaging spectroscopy (EPIC) and Reflective Grating Spectrometer (RGS) data to investigate properties of the remnant and its environment. The X-ray spectra were analyzed with SPEX software package. In addition to this we performed a numerical hydrodynamic simulation of the remnant. The EPIC data show prominent Fe K line emission, but the deduced overall amount of iron in the shocked ejecta is low. The data also show that the remnant has an asymmetric eje…
A comparison of X-ray observations of the Cassiopeia A supernova remnant taken in 2000, 2002, and 2004 with the Chandra ACIS-S3 reveals the presence of several small scale features (<= 10 arcsec) which exhibit significant intensity changes over a 4 year time frame. Here we report on the variability of six features, four of which show count rate increases from ~ 10% to over 90%, and two which show decreases of ~ 30% -- 40%. While extracted 1-4.5 keV X-ray spectra do not reveal gross changes in emission line strengths, spectral fits using non-equilibrium ionization, metal-rich plasma models indi…
0103$-$72.6, the second brightest X-ray supernova remnant (SNR) in the Small Magellanic Cloud (SMC), has been observed with the {\it Chandra X-Ray Observatory}. Our {\it Chandra} observation unambiguously resolves the X-ray emission into a nearly complete, remarkably circular shell surrounding bright clumpy emission in the center of the remnant. The observed X-ray spectrum for the central region is evidently dominated by emission from reverse shock-heated metal-rich ejecta. Elemental abundances in this ejecta material are particularly enhanced in oxygen and neon, while less prominent in the he…
Two ROSAT high resolution images separated by nearly five years have been used to determine the expansion of the X-ray remnant of Tycho's supernova (SN1572). The current expansion rate averaged over the entire remnant is $0.124\pm0.011$ % per yr, which, when combined with the known age of the remnant, determines the mean expansion parameter $m$, defined as $R\propto t^m$, to be $0.54\pm0.05$. There are significant radial and azimuthal variations of the X-ray expansion rate. The radial expansion in particular shows highly significant evidence for the more rapid expansion of the forward blast wa…
We report on the discovery of X-ray emission from SN 1970G in M101, 35 years after its outburst, using deep X-ray imaging with the Chandra X-ray observatory. The Chandra ACIS spectrum shows that the emission is soft (<2 keV) and characteristic for the reverse shock region. The X-ray luminosity (1 x 10^37 ergs/s) is likely caused by the interaction of the supernova (SN) shock with dense circumstellar matter. If the material was deposited by the stellar wind from the progenitor, a mass-loss rate of (2.6+/-0.4) x 10^-5 M_sun/year is inferred. Utilizing the high-resolution Chandra ACIS data of SN …
We examine the hypothesis that some supernova remnants (SNRs) may be responsible for some unidentified gamma-ray sources detected by EGRET instrument aboard the Compton Gamma Ray Observatory. If this is the case, gamma-rays are produced via pion production and decay from direct inelastic collisions of accelerated by SNR shock wave ultrarelativistic protons with target protons of the interstellar medium. We develop a 3-D hydrodynamical model of SNR IC 443 as a possible cosmic gamma-ray source 2EG J0618+2234. The derived parameters of IC 443: the explosion energy E_o=2.7*10^{50} erg, the initial…
Chandra High Energy Transmission Grating Spectrometer observations of the supernova remnant 1E0102.2-7219 in the Small Magellanic Cloud reveal a spectrum dominated by X-ray emission lines from hydrogen-like and helium-like ions of oxygen, neon, magnesium and silicon, with little iron. The dispersed spectrum shows a series of monochromatic images of the source in the light of individual spectral lines. Detailed examination of these dispersed images reveals Doppler shifts within the supernova remnant, indicating bulk matter velocities on the order of 1000 km/s. These bulk velocities suggest an e…
We present new X-ray imaging and spectroscopy of a composite supernova remnant G327.1-1.1 using the Chandra and XMM-Newton X-ray observatories. G327.1-1.1 has an unusual morphology consisting of a symmetric radio shell and an off center nonthermal component that indicates the presence of a pulsar wind nebula (PWN). Radio observations show a narrow finger of emission extending from the PWN structure towards the northwest. X-ray studies with ASCA, ROSAT, and BeppoSAX revealed elongated extended emission and a compact source at the tip of the finger that may be coincident with the actual pulsar. …
Young supernova remnants such as Tycho generally exhibit a bright circular clumpy shell in both radio and X-ray emission. For several young remnants, various arguments suggest that the magnetic field is larger than can be explained by compression of a few $μG$ ambient magnetic field by the shock wave. Radio polarization studies reveal a net radial orientation of magnetic fields in the shell which cannot be explained by the simple compression either. We model Rayleigh-Taylor instability at the interface of the ejecta and the shocked ambient medium to explain these observations. We have performe…
We present new (2004 July) G750L and G140L Space Telescope Imaging Spectrograph (STIS) data of the H-alpha and Ly-alpha emission from supernova remnant (SNR) 1987A. With the aid of earlier data, from Oct 1997 to Oct 2002, we track the local evolution of Ly-alpha emission and both the local and global evolution of H-alpha emission. In addition to emission which we can clearly attribute to the surface of the reverse shock, we also measure comparable emission, in both H-alpha and Ly-alpha, which appears to emerge from supernova debris interior to the surface. New observations taken through slits …
We present observations of the young, Oxygen-rich supernova remnant 1E0102.2-7219 taken by the Chandra X-ray Observatory during Chandra's Orbital Activation and Checkout phase. The boundary of the blast wave shock is clearly seen for the first time, allowing the diameter of the remnant and the mean blast wave velocity to be determined accurately. The prominent X-ray bright ring of material may be the result of the reverse shock encountering ejecta; the radial variation of O VII vs. O VIII emission indicates an ionizing shock propagating inwards, possibly through a strong density gradient in th…
A new epoch of VLA measurements of Kepler's supernova remnant was obtained to make accurate measurements of the radio spectral index variations and polarization. We have compared these new radio images with Halpha, infrared, and X-ray data to better understand the three dimensional structure and dynamics of Kepler, and to better understand the physical relationships between the various nonthermal and thermal plasmas. Spatial variations in the radio spectral index from -0.85 to -0.6 are observed between 6 cm and 20 cm. There is a strong correspondence between the radial and azimuthal profiles o…
Chandra X-ray observations of DEM L71, a supernova remnant (SNR) in the Large Magellanic Cloud (LMC), reveal a clear double shock morphology consisting of an outer blast wave shock surrounding a central bright region of reverse-shock heated ejecta. The abundances of the outer shock are consistent with LMC values, while the ejecta region shows enhanced abundances of Si, Fe, and other species. However, oxygen is not enhanced in the ejecta; the Fe/O abundance ratio there is more than 5 times the solar ratio. Based on the relative positions of the blast wave shock and the contact discontinuity in …
A number of supernova remnants (SNRs) show nonthermal X-rays assumed to be synchrotron emission from shock accelerated TeV electrons. The existence of these TeV electrons strongly suggests that the shocks in SNRs are sources of galactic cosmic rays (CRs). In addition, there is convincing evidence from broad-band studies of individual SNRs and elsewhere that the particle acceleration process in SNRs can be efficient and nonlinear. If SNR shocks are efficient particle accelerators, the production of CRs impacts the thermal properties of the shock heated, X-ray emitting gas and the SNR evolution.…
We present the deepest optical spectrum acquired to date of Balmer-dominated shocks in the NW rim of SN 1006. We detect the broad and narrow components of H-alpha, H-beta and H-gamma and report the first detection of the He I 6678 emission line in this supernova remnant. We may have detected, at the 1.5-sigma level, faint He II 4686 emission. We measure a full width half maximum of 2290 +/- 80 km/s in the broad component H-alpha line, with broad-to-narrow flux ratios of 0.84^+(0.03)_(-0.01) and 0.93^(+0.18)_(-0.16) in H-alpha and H-beta, respectively. To match these observations, our nonradiat…
We report an up-turn in the soft X-ray light curve of supernova remnant (SNR) 1987A in late 2003 (~6200 days after the explosion), as observed with the Chandra X-ray Observatory. Since early 2004, the rapid increase of the 0.5-2 keV band X-ray light curve can no longer be described by the exponential density distribution model with which we successfully fitted the data between 1990 and 2003. Around day ~6200, we also find that the fractional contribution to the observed soft X-ray flux from the decelerated shock begins to exceed that of the fast shock and that the X-ray brightening becomes "gl…
