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Supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

Optical observations of young supernova remnants can give information on the abundance structure of the supernova ejecta, from which properties of the supernova explosion can be deduced. Young remnants also act as laboratories for fast shock wave phenomena. Observations of X-ray and optical line emission show that while a collisionless shock wave does form, it is far from thermal equilibrium. Some young remnants are promising candidates for particle acceration in shock waves, while in other remnants a central compact object is probably responsible for particle acceleration.

Chevalier, R.A.

1981-01-01

2

Supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

The absolute abundances of elements in the remnant of Tycho's supernova are estimated from the results of the X-ray observation with the satellite Tenma. It is shown that they are in rough agreement with the prediction by a carbon deflagration model for Type I supernovae. The optical emission-line spectra of the fast-moving, oxygen filaments in the Puppis A supernova remnant are not well reproduced by simple shock excitation models.

Itoh, Hiroshi

1987-03-01

3

Supernova remnants  

International Nuclear Information System (INIS)

[en] The absolute abundances of elements in the remnant of Tycho's supernova are estimated from the results of the X-ray observation with the satellite Tenma. It is shown that they are in rough agreement with the prediction by a carbon deflagration model for Type I supernovae. The optical emission-line spectra of the fast-moving, oxygen filaments in the Puppis A supernova remnant are not well reproduced by simple shock excitation models. (author)

1987-01-01

4

Cosmic Ray Spectrum in Supernova Remnant Shocks  

CERN Multimedia

We perform kinetic simulations of diffusive shock acceleration (DSA) in Type Ia supernova remnants (SNRs) expanding into a uniform interstellar medium (ISM). Bohm-like diffusion assumed, and simple models for Alfvenic drift and dissipation are adopted. Phenomenological models for thermal leakage injection are considered as well. We find that the preshock gas temperature is the primary parameter that governs the cosmic ray (CR) acceleration efficiency and energy spectrum, while the CR injection rate is a secondary parameter. For SNRs in the warm ISM, if the injection fraction is larger than 10^{-4}, the DSA is efficient enough to convert more than 20 % of the SN explosion energy into CRs and the accelerated CR spectrum exhibits a concave curvature flattening to E^{-1.6}. Such a flat source spectrum near the knee energy, however, may not be reconciled with the CR spectrum observed at Earth. On the other hand, SNRs in the hot ISM, with an injection fraction smaller than 10^{-4}, are inefficient accelerators with...

Kang, Hyesung

2010-01-01

5

Collisionless shock and supernova remnant simulations on VULCAN  

International Nuclear Information System (INIS)

The VULCAN [C. N. Danson et al., Opt. Commun. 103, 392 (1993)] laser at the UK Central Laser Facility is being used for laboratory-based simulations of collisionless shocks. By ensuring that key dimensionless parameters in the experiments have values similar to those of supernova remnants (SNRs), the hydrodynamics and magnetic field of the experiment are scaled to those of a SNR. This makes it possible to investigate experimentally the physics of collisionless magnetized shocks in such objects. The experiments are providing data against which to test current theory. Collisionless shock formation and the interaction of two counterpropagating colliding plasmas permeated by a strong magnetic field are discussed.

2001-01-01

6

Grain Destruction in a Supernova Remnant Shock Wave  

CERN Multimedia

Dust grains are sputtered away in the hot gas behind shock fronts in supernova remnants, gradually enriching the gas phase with refractory elements. We have measured emission in C IV $\\lambda$1550 from C atoms sputtered from dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock agrees approximately with predictions from model calculations that match the Spitzer 24 micron and the X-ray intensity profiles. Thus these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates used in models. However, there is a discrepancy in that the CIV intensity 10" behind the shock is too high compared to the intensities at the shock and 25" behind it. Variations in the density, hydrogen neutral fraction and the dust properties over parsec scales in the pre-shock medium limit our ability to test dust destruction models in detail.

Raymond, John C; Williams, Brian J; Blair, William P; Borkowski, Kazimierz J; Gaetz, Terrance J; Sankrit, Ravi

2013-01-01

7

Optical emission from shocks. V. The Magellantic Cloud supernova remnants  

International Nuclear Information System (INIS)

[en] High-resolution ?Vapprox. =25 km s-1 velocity data on Magellanic Cloud supernova remnants (SNRs) in the [O II] doublet obtained with the 3.9 m Anglo-Australian telescope combined with absolute H? photometry obtained with the 1 m telescope at Siding Spring have been shown to be inconsistent with any model requiring the interstellar medium to be homogeneous about, or smoothly varying away from, the explosion center. However, the data do give very strong support to the cloudlet shock model put forward by McKee and co-workers. The cloudlets have a mean density around 12 cm-3 and are generally less than a parsec across. The mean kinetic energy deposited by the supernova is 51.3 > or approx. = logE > or approx. = 50.3, with a probable value near 7 x 1050 ergs

1979-01-01

8

Self consistent particle acceleration in 2D supernova remnant shocks  

Science.gov (United States)

We present numerical solutions of a two dimensional, self consistent model of cosmic ray modified, supernova remnant shocks developed by Zakharian (2000). The equations of the model consist of the Parker transport equation for the energetic particle momentum distribution function, f, including convection, anisotropic diffusion, drifts, and adiabatic energy changes. The transport equation is coupled self consistently, with the equations of ideal magnetohydrodynamics (MHD) describing the thermal plasma, but suitably modified to take into account injection at the shock, and with an extra force - pc, exerted by the cosmic ray pressure pc in the momentum equation for the system. The model incorporates anisotropic diffusion of the cosmic rays, including diffusion parallel (? ), and perpendicular (??) to the mean magnetic field, and the role of particle drifts due to the anti-symmetric diffusion coefficient ?A. For the case of an initially uniform background magnetic field, the anisotropic diffusion of the cosmic rays leads to an anisotropic spatial distribution of thermal plasma, cosmic rays and magnetic field. The shock is quasi-parallel over the poles (? = 0° ), and quasi-perpendicular near the equator (? = 90° ), where ? = 0° corresponds to the initial magnetic field direction. The evolution of the SNR shock, and the momentum distribution f(r, p, t) of the energetic particles are investigated. The dependence of the solutions and acceleration rate at the shock on the parameter ? = ??/? and the shock obliquity ? are studied in detail.

Zakharian, A. R.; Webb, G. M.; Brio, M.; Jokipii, J. R.

2001-08-01

9

Supernova remnants  

International Nuclear Information System (INIS)

[en] Supernovae play an essential role for the physical conditions in the interstellar medium, in the chemical evolution of the galaxy, in the formation of pulsars and possibly also of X-ray sources and perhaps also in the production of cosmic rays. Each year several supernovae are discovered in external galaxies, partly as a result of systematic searches. Also, in our own galaxy some supernovae have been seen during historical times (SN 1054; Crab Nebula, SN 1572: Tycho's nova, SN 1604: Kepler's nova; other somewhat less certain supernovae appeared in 1006 and in 185, while additional ones may have been suggested). In all cases the supernovae in our galaxy seem to have left an extended non-thermal radio source. It is now generally believed that virtually all such radio sources in our galaxy are actually supernova remnants. (Auth.)

1975-07-13

10

Postshock turbulence and diffusive shock acceleration in young supernova remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thin X-ray filaments are observed in the vicinity of young supernova remnants (SNR) blast waves. Identifying processes involved in the creation of such filaments would provide a direct insight of particle acceleration occurring within SNR, in particular regarding the cosmic ray yield issue. Aims. Th...

Marcowith, A.; Casse, F.

11

Supernova remnants and the interstellar medium  

Energy Technology Data Exchange (ETDEWEB)

This book focuses on the mutual interaction between supernova and the resultant individual remnant nebula, and the detailed state of the circumstellar and interstellar medium surrounding the supernova. It includes chapter on: The early evolution of supernova remnants; Recent x-ray observations of supernova remnants and their interpretation; Line emission processes in atomic and molecular shocks; Radio studies of supernova remnants: patterns and statistics; and Infrared analysis of supernova remnants.

Roger, R.S.; Landecker, T.L.

1988-01-01

12

Comment on 'Collisionless shock and supernova remnant simulations on VULCAN' [Phys. Plasmas 8, 2439 (2001)  

International Nuclear Information System (INIS)

This recent paper reports some real advances in experimental technique, but is misleading or incorrect in several places. First, the design assumes without discussion that the magnetic field will completely penetrate the plasma, but this is not likely. Second, when the magnetic field is present the surfaces of the converging plasmas will be Rayleigh-Taylor unstable. Third, any shocks produced in experiments like those reported may be collisionless but have no relevance to shocks in supernova remnants. Fourth, the experiment is not a meaningful hydrodynamic simulation of a supernova remnant. Finally, the hydrodynamic simulation results reported are also in error, leading to incorrect values for some scaling parameters.

2002-01-01

13

Existence and interpretation of smooth cosmic-ray dominated shock structures in supernova remnants  

CERN Document Server

Studies of energetic particle acceleration at collisionless shocks by the diffusive shock acceleration process indicate that completely smooth cosmic ray dominated shock structures are possible. The existence of these is discussed and conditions for their existence derived. It is shown that such solutions cannot dominate the evolution of supernova remnants if the particle diffusion coefficient has the expected strong momentum dependence To appear in Astronomy and Astrophysics, July 1995, vol 299 pp 222-224

O'Connor-Drury, L; Berezhko, E G; Drury, L O'C

1995-01-01

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On the plasma temperature in supernova remnants with cosmic-ray modified shocks  

CERN Document Server

Context: Multiwavelength observations of supernova remnants can be explained within the framework of the diffusive shock acceleration theory, which allows effective conversion of the explosion energy into cosmic rays. Although the models of nonlinear shocks describe reasonably well the nonthermal component of emission, certain issues, including the heating of the thermal plasma and the related X-ray emission, remain still open. Aims: To discuss how the evolution and structure of supernova remnants is affected by strong particle acceleration at the forward shock. Methods: Analytical estimates combined with detailed discussion of the physical processes. Results: The overall dynamics is shown to be relatively insensitive to the amount of particle acceleration, but the post-shock gas temperature can be reduced to a relatively small multiple, even as small as six times, the ambient temperature with a very weak dependence on the shock speed. This is in marked contrast to pure gas models where the temperature is ins...

O'Connor-Drury, L; Malyshev, D; Gabici, S

2008-01-01

15

PROGENITORS OF RECOMBINING SUPERNOVA REMNANTS  

Energy Technology Data Exchange (ETDEWEB)

Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with ionization temperature higher than the electron temperature, has been recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the supernova explosion. If the circumstellar medium is dense enough, collisional ionization equilibrium can be established in the early stage of the evolution of the supernova remnant and subsequent adiabatic cooling, which occurs after the shock wave gets out of the dense circumstellar medium, makes the electron temperature lower than the ionization temperature. We study the circumstellar medium around several supernova progenitors and show which supernova progenitors can have a circumstellar medium dense enough to establish collisional ionization equilibrium soon after the explosion. We find that the circumstellar medium around red supergiants (especially massive ones) and the circumstellar medium dense enough to make Type IIn supernovae can establish collisional ionization equilibrium soon after the explosion and can evolve to become recombining supernova remnants. Wolf-Rayet stars and white dwarfs have the possibility to be recombining supernova remnants but the fraction is expected to be very small. As the occurrence rate of the explosions of red supergiants is much higher than that of Type IIn supernovae, the major progenitors of recombining supernova remnants are likely to be red supergiants.

Moriya, Takashi J., E-mail: takashi.moriya@ipmu.jp [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8583 (Japan)

2012-05-01

16

An Integral View of Balmer-dominated Shocks in Supernova Remnants  

CERN Document Server

We present integral-field spectroscopic observations with the VIMOS-IFU at the VLT of fast (2000-3000 km/s) Balmer-dominated shocks surrounding the northwestern rim of the remnant of supernova 1006. The high spatial and spectral resolution of the instrument enable us to show that the physical characteristics of the shocks exhibit a strong spatial variation over few atomic scale lengths across 133 sky locations. Our results point to the presence of a population of non-thermal protons (10-100 keV) which might well be the seed particles for generating high-energy cosmic rays. We also present observations of Tycho's supernova remnant taken with the narrow-band tunable filter imager OSIRIS at the GTC and the Fabry-Perot interferometer GHaFaS at the WHT to resolve respectively the broad and narrow H\\alpha\\ lines across a large part of the remnant.

Nikoli?, Sladjana; Heng, Kevin; Kupko, Daniel; Méndez-Abreu, Jairo; Aguerri, J Alfonso L; Serra, Joan Font; Beckman, John

2013-01-01

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Optical emission from a fast shock wave: The remnants of Tycho's supernova and SN 1006  

International Nuclear Information System (INIS)

[en] The faint optical filaments in Tycho's supernova remnant appear to be emission from a shock front moving at 5600 km s-1. The intensity of the hydrogen lines, the absence of forbidden lines of heavy elements in the spectrum, and the width of the filaments are explained by a model in which a collisionless shock wave is moving into partially neutral gas. The presence of the neutral gas can be used to set an upper limit of approximately 5 x 1047 ergs to the energy in ionizing radiation emitted by a Type I supernova. The patchy neutral gas is probably part of the warm neutral component of the interstellar medium. The existing information on the remnant of SN 1006 indicates that its emission is similar in nature to that from Tycho's remnant

1978-10-01

18

Electron-Ion Temperature Equilibration in Collisionless Shocks: the Supernova Remnant-Solar Wind Connection  

CERN Multimedia

Collisionless shocks are loosely defined as shocks where the transition between pre-and post-shock states happens on a length scale much shorter than the collisional mean free path. In the absence of collision to enforce thermal equilibrium post-shock, electrons and ions need not have the same temperatures. While the acceleration of electrons for injection into shock acceleration processes to produce cosmic rays has received considerable attention, the related problem of the shock heating of quasi-thermal electrons has been relatively neglected. In this paper we review that state of our knowledge of electron heating in astrophysical shocks, mainly associated with supernova remnants (SNRs), shocks in the solar wind associated with the terrestrial and Saturnian bowshocks, and galaxy cluster shocks. The solar wind and SNR samples indicate that the ratio of electron temperature to ion temperature declines with increasing shock speed or Alfvenic Mach number. We discuss the extent to which such behavior can be unde...

Ghavamian, Parviz; Mitchell, Jeremy; Masters, Adam; Laming, J Martin

2013-01-01

19

THE ROLE OF DIFFUSIVE SHOCK ACCELERATION ON NONEQUILIBRIUM IONIZATION IN SUPERNOVA REMNANT SHOCKS. II. EMITTED SPECTRA  

International Nuclear Information System (INIS)

We present a grid of nonequilibrium ionization models for the X-ray spectra from supernova remnants undergoing efficient diffusive shock acceleration. The calculation follows the hydrodynamics of the blast wave as well as the time-dependent ionization of the plasma behind the shock. The ionization state is passed to a plasma emissivity code to compute the thermal X-ray emission, which is combined with the emission from nonthermal synchrotron emission to produce a self-consistent model for the thermal and nonthermal emission from cosmic-ray dominated shocks. We show how plasma diagnostics such as the G'-ratio of He-like ions, defined as the ratio of the sum of the intercombination, forbidden, and satellite lines to the resonance line, can vary with acceleration efficiency, and discuss how the thermal X-ray emission, when the time-dependent ionization is not calculated self-consistently with the hydrodynamics, can differ from the thermal X-ray emission from models which do account for the hydrodynamics. Finally, we compare the thermal X-ray emission from models which show moderate acceleration (?35%) to the thermal X-ray emission from test-particle models.

2010-12-20

20

OH 1720 MHz Masers in Supernova Remnants C-Shock Indicators  

CERN Document Server

Recent observations show that the OH 1720 MHz maser is a powerful probe of the shocked region where a supernova remnant strikes a molecular cloud. We perform a thorough study of the pumping of this maser and find tight constraints on the physical conditions needed for its production. The presence of the maser implies moderate temperatures (50 -- 125 K) and densities ($\\sim 10^5 cm^{-3}$), and OH column densities of order $10^{16} cm^{-2}$. We show that these conditions can exist only if the shocks are of C-type. J-shocks fail by such a wide margin that the presence of this maser could become the most powerful indicator of C-shocks. These conditions also mean that the 1720 MHz maser will be inherently weak compared to the other ground state OH masers. All the model predictions are in good agreement with the observations.

Lockett, P; Elitzur, M; Lockett, Phil; Gauthier, Eric; Elitzur, Moshe

1999-01-01

 
 
 
 
21

Optical emission from a fast shock wave with application to supernova remnants  

International Nuclear Information System (INIS)

[en] We have observed the spectrum of Tycho's supernova remnant and have detected only the H?, H?, and H? lines. The H? line profile can be divided into two components: one with a width consistent with the instrumental resolution and one with a full width at half-maximum (FWHM) of 1800 +- 200 km s-1. The two components have similar intensities. The observations are interpreted in terms of a shock wave model. The shock wave is presumably encountering neutral atoms that have some probability of giving line emission before being ionized by the post-shock gas. Charge exchange can occur in the post-shock region, giving rise to a broad emission component from a population of fast neutral atoms. The ratio of broad to narrow emission components is a sensitive function of shock velocity because the charge-exchange cross section depends strongly on the proton velocity. For Tycho's remnant, both the ratio of broad to narrow emission and the FWHM of the broad emission can be fitted if the shock velocity is 2300 +- 500 km s-1. Combined with the proper motion of the filament as found by Kamper and van den Bergh, the distance to Tycho's remnant is about 2.3 +- 0.5 kpc. The absolute photographic magnitude of Tycho's supernova at maximum is then -18.8 +- 1.3, which is consistent with the absolute magnitudes of extragalactic Type I supernovae at maximum light.The shock model can be applied to some other emission nebulae. We predict that a broad emission component should be present in the H? line profile of the remnant of SN 1006. If the model applies to the high-velocity emission regions in the Cygnus Loop observed by Kirshner and Taylor, we expect the high-velocity components to have a width approximately equal to half their velocity shift and to be unobservable in forbidden emission lines of heavy elements. The model may also apply to the high-velocity emission region observed by Elliott near eta Carinae

1980-01-01

22

Optical emission from a fast shock wave with application to supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

We have observed the spectrum of Tycho's supernova remnant and have detected only the H..cap alpha.., H..beta.., and H..gamma.. lines. The H..cap alpha.. line profile can be divided into two components: one with a width consistent with the instrumental resolution and one with a full width at half-maximum (FWHM) of 1800 +- 200 km s/sup -1/. The two components have similar intensities. The observations are interpreted in terms of a shock wave model. The shock wave is presumably encountering neutral atoms that have some probability of giving line emission before being ionized by the post-shock gas. Charge exchange can occur in the post-shock region, giving rise to a broad emission component from a population of fast neutral atoms. The ratio of broad to narrow emission components is a sensitive function of shock velocity because the charge-exchange cross section depends strongly on the proton velocity. For Tycho's remnant, both the ratio of broad to narrow emission and the FWHM of the broad emission can be fitted if the shock velocity is 2300 +- 500 km s/sup -1/. Combined with the proper motion of the filament as found by Kamper and van den Bergh, the distance to Tycho's remnant is about 2.3 +- 0.5 kpc. The absolute photographic magnitude of Tycho's supernova at maximum is then -18.8 +- 1.3, which is consistent with the absolute magnitudes of extragalactic Type I supernovae at maximum light.The shock model can be applied to some other emission nebulae. We predict that a broad emission component should be present in the H..cap alpha.. line profile of the remnant of SN 1006. If the model applies to the high-velocity emission regions in the Cygnus Loop observed by Kirshner and Taylor, we expect the high-velocity components to have a width approximately equal to half their velocity shift and to be unobservable in forbidden emission lines of heavy elements. The model may also apply to the high-velocity emission region observed by Elliott near eta Carinae.

Chevalier, R.A.; Kirshner, R.P.; Raymond, J.C.

1980-01-01

23

3-D Model of Broadband Emission from Supernova Remnants Undergoing Non-linear Diffusive Shock Acceleration  

Energy Technology Data Exchange (ETDEWEB)

We present a 3-dimensional model of supernova remnants (SNRs) where the hydrodynamical evolution of the remnant is modeled consistently with nonlinear diffusive shock acceleration occurring at the outer blast wave. The model includes particle escape and diffusion outside of the forward shock, and particle interactions with arbitrary distributions of external ambient material, such as molecular clouds. We include synchrotron emission and cooling, bremsstrahlung radiation, neutral pion production, inverse-Compton (IC), and Coulomb energy-loss. Boardband spectra have been calculated for typical parameters including dense regions of gas external to a 1000 year old SNR. In this paper, we describe the details of our model but do not attempt a detailed fit to any specific remnant. We also do not include magnetic field amplification (MFA), even though this effect may be important in some young remnants. In this first presentation of the model we don't attempt a detailed fit to any specific remnant. Our aim is to develop a flexible platform, which can be generalized to include effects such as MFA, and which can be easily adapted to various SNR environments, including Type Ia SNRs, which explode in a constant density medium, and Type II SNRs, which explode in a pre-supernova wind. When applied to a specific SNR, our model will predict cosmic-ray spectra and multi-wavelength morphology in projected images for instruments with varying spatial and spectral resolutions. We show examples of these spectra and images and emphasize the importance of measurements in the hard X-ray, GeV, and TeV gamma-ray bands for investigating key ingredients in the acceleration mechanism, and for deducing whether or not TeV emission is produced by IC from electrons or pion-decay from protons.

Lee, Shiu-Hang; Kamae, Tuneyoshi; Ellison, Donald C.

2008-07-02

24

Electron acceleration due to high frequency instabilities at supernova remnant shocks  

CERN Document Server

Observations of synchrotron radiation across a wide range of wavelengthsprovide clear evidence that electrons are accelerated to relativistic energiesin supernova remnants (SNRs). However, a viable mechanism for thepre-acceleration of such electrons to mildly relativistic energies has not yetbeen established. In this paper an electromagnetic particle-in-cell (PIC) codeis used to simulate acceleration of electrons from background energies to tensof keV at perpendicular collisionless shocks associated with SNRs. Free energyfor electron energization is provided by ions reflected from the shock front,with speeds greater than the upstream electron thermal speed. The PICsimulation results contain several new features, including: the acceleration,rather than heating, of electrons via the Buneman instability; the accelerationof electrons to speeds exceeding those of the shock-reflected ions producingthe instability; and strong acceleration of electrons perpendicular to themagnetic field. Electron energization takes p...

Dieckmann, M E; Chapman, S C; Dendy, R O; O'Connor-Drury, L

2000-01-01

25

A cosmic-ray precursor model for a Balmer-dominated shock in Tycho's supernova remnant  

CERN Multimedia

We present a time-dependent cosmic-ray modified shock model for which the calculated H-alpha emissivity profile agrees well with the H-alpha flux increase ahead of the Balmer-dominated shock at knot g in Tycho's supernova remnant, observed by Lee et al (2007). The backreaction of the cosmic ray component on the thermal component is treated in the two-fluid approximation, and we include thermal particle injection and energy transfer due to the acoustic instability in the precursor. The transient state of our model that describes the current state of the shock at knot g, occurs during the evolution from a thermal gas dominated shock to a smooth cosmic-ray dominated shock. Assuming a distance of 2.3 kpc to Tycho's remnant we obtain values for the cosmic ray diffusion coefficient, the injection parameter, and the time scale for the energy transfer of 10^{24} cm^{2} s^{-1}, 4.2x10^{-3}, and 426 y, respectively. We have also studied the parameter space for fast (300 km s^{-1} - 3000 km s^{-1}), time-asymptotically ...

Wagner, A Y; Raymond, J C; Hartquist, T W; Falle, S A E G

2008-01-01

26

THE ROLE OF DIFFUSIVE SHOCK ACCELERATION ON NONEQUILIBRIUM IONIZATION IN SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

We present results of semianalytic calculations which show clear evidence for changes in the nonequilibrium ionization behind a supernova remnant forward shock undergoing efficient diffusive shock acceleration (DSA). The efficient acceleration of particles (i.e., cosmic rays (CRs)) lowers the shock temperature and raises the density of the shocked gas, thus altering the ionization state of the plasma in comparison to the test-particle (TP) approximation where CRs gain an insignificant fraction of the shock energy. The differences between the TP and efficient acceleration cases are substantial and occur for both slow and fast temperature equilibration rates: in cases of higher acceleration efficiency, particular ion states are more populated at lower electron temperatures. We also present results which show that, in the efficient shock acceleration case, higher ionization fractions are reached noticeably closer to the shock front than in the TP case, clearly indicating that DSA may enhance thermal X-ray production. We attribute this to the higher postshock densities which lead to faster electron temperature equilibration and higher ionization rates. These spatial differences should be resolvable with current and future X-ray missions, and can be used as diagnostics in estimating the acceleration efficiency in CR-modified shocks.

2009-05-10

27

DUST DESTRUCTION IN A NON-RADIATIVE SHOCK IN THE CYGNUS LOOP SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

We present 24 ?m and 70 ?m images of a non-radiative shock in the Cygnus Loop supernova remnant, obtained with the Multiband Imaging Photometer for Spitzer on board the Spitzer Space Telescope. The post-shock region is resolved in these images. The ratio of the 70 ?m to the 24 ?m flux rises from about 14 at a distance 0.'1 behind the shock front to about 22 in a zone 0.'75 further downstream, as grains are destroyed in the hot plasma. Models of dust emission and destruction using post-shock electron temperatures between 0.15 keV and 0.30 keV and post-shock densities, nH? 2.0 cm-3, predict flux ratios that match the observations. Non-thermal sputtering (i.e., sputtering due to bulk motion of the grains relative to the gas) contributes significantly to the dust destruction under these shock conditions. From the model calculations, we infer that about 35% by mass of the grains are destroyed over a 0.14 pc region behind the shock front.

2010-04-01

28

Galactic Cosmic Rays from Supernova Remnants; 2, Shock Acceleration of Gas and Dust  

CERN Document Server

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, (iii) frictional energy losses of the grains colliding with the gas, (iv) sputtering of ions of refractory elements from the accelerated grains and (v) the further shock acceleration of the sputtered ions to cosmic ray energies. The calculated GCR composition and spectra are in good agreement with observations.

Ellison, D C; Meyer, J P; Ellison, Donald C.; Meyer, Jean-Paul

1997-01-01

29

OH Masers and Supernova Remnants  

Science.gov (United States)

OH(1720 MHz) masers are created by the interaction of supernova remnants with molecular clouds. These masers are pumped by collisions in warm, shocked molecular gas with OH column densities in the range 1016-1017, cm-2. Excitation calculations suggest that inversion of the 6049 MHz OH line may occur at the higher column densities that have been inferred from main-line absorption studies of supernova remnants with the Green Bank Telescope. OH(6049 MHz) masers have therefore been proposed as a complementary indicator of remnant-cloud interaction. This motivated searches for 6049 MHz maser emission from supernova remnants using the Parkes 63 m and Effelsberg 100 m telescopes, and the Australia Telescope Compact Array. A total of forty-one remnants have been examined by one or more of these surveys, but without success. To check the accuracy of the OH column densities inferred from the single-dish observations we modelled OH absorption at 1667 MHz observed with the Very Large Array towards three supernova remnants, IC 443, W44 and 3C 391. The results are mixed - the OH column is revised upwards in IC443, downwards in 3C391, and is somewhat reduced in W44. We conclude that OH columns exceeding 1017 cm-2 are indeed present in some supernova remnants and so the lack of any detections is not explained by low OH column density. We discuss the possibility that non-local line overlap is responsible for suppressing the inversion of the 6049 MHz line.

Wardle, Mark; McDonnell, Korinne

2012-07-01

30

Infrared analysis of supernova remnants  

International Nuclear Information System (INIS)

Infrared observations of supernova remnants obtained with the infrared astronomical satellite provide new insights into the dynamics and energetics of the remnants, and into their interaction with the ambient interstellar medium. In most remnants the infrared emission arises from dust that is collisonally heated by the x-ray emitting gas. The infrared observations can therefore be used as a diagnostic for the physical conditions of the shocked gas. In particular, it is shown that all the prominent x-ray remnants in the galaxy and in the LMC cool mainly by dust grain collisions instead of atomic processes.

1988-01-01

31

A Generalized Model of Nonlinear Diffusive Shock Acceleration Coupled to an Evolving Supernova Remnant  

CERN Multimedia

To better model the efficient production of cosmic rays (CRs) in supernova remnants (SNRs) with the associated coupling between CR production and SNR dynamics, we have generalized an existing cr-hydro-NEI code (i.e., Ellison et al. 2012) to include the following processes: (1) an explicit calculation of the upstream precursor structure including the position dependent flow speed, density, temperature, and magnetic field strength; (2) a momentum and space dependent CR diffusion coefficient; (3) an explicit calculation of magnetic field amplification (MFA); (4) calculation of the maximum CR momentum using the amplified magnetic field; (5) a finite Alfven speed for the particle scattering centers; and (6) the ability to accelerate a superthermal seed population of CRs as well as the ambient thermal plasma. While a great deal of work has been done modeling SNRs, most work has concentrated on either the continuum emission from relativistic electrons or ions, or the thermal emission from the shock heated plasma. Ou...

Lee, Shiu-Hang; Nagataki, Shigehiro

2012-01-01

32

Magnetic Turbulence Production by Cosmic Rays Drifting Upstream of Supernova Remnant Shocks  

Science.gov (United States)

We present results of two- and three-dimensional Particle-In-Cell simulations of magnetic turbulence production by isotropic cosmic-ray ions drifting upstream of supernova remnant shocks. The studies aim at testing predictions of a strong amplification of short-wavelength nonresonant wave modes and at studying the subsequent evolution of the magnetic turbulence and its backreaction on cosmic ray trajectories. The detailed knowledge of the upstream turbulence properties is crucial to ascertain all aspects of the shock acceleration process-the transport properties of cosmic rays, the shock structure, thermal particle injection and heating processes. An amplification of magnetic field would also facilitate the acceleration of particles beyond the ``knee'' in the cosmic-ray spectrum. We confirm the generation of the turbulent magnetic field due to the drift of cosmic-ray ions in the upstream plasma but find that the amplitude of the turbulence saturates at about ?B/B~1. The backreaction of the magnetic turbulence on the particles leads to an alignment of the bulk-flow velocities of the cosmic rays and the background medium. This is an essential characteristic of cosmic-ray modified shocks: the upstream flow speed is continuously changed by the cosmic rays. The deceleration of the cosmic-ray drift and the simultaneous bulk acceleration of the background plasma account for the saturation of the instability at moderate amplitudes of the magnetic field. A strong magnetic field amplification to amplitudes ?B>>B0 has not been demonstrated yet.

Niemiec, Jacek; Pohl, Martin; Stromal, Thomas; Nishikawa, Ken-Ichi

2008-12-01

33

SUBARU HDS Observations of a Balmer-Dominated Shock in Tycho's Supernova Remnant  

CERN Document Server

We present an Ha spectral observation of a Balmer-dominated shock on the eastern side of Tycho's supernova remnant using the Subaru Telescope. Utilizing the High Dispersion Spectrograph (HDS), we measure the spatial variation of the line profile between preshock and postshock gas. Our observation clearly shows a broadening and centroid shift of the narrow-component postshock Ha line relative to the Ha emission from the preshock gas. The observation supports the existence of a thin precursor where gas is heated and accelerated ahead of the shock. Furthermore, the spatial profile of the emission ahead of the Balmer filament shows a gradual gradient in the Ha intensity and line width ahead of the shock. We propose that this region (~10^16 cm) is likely to be the spatially resolved precursor. The line width increases from ~30 up to ~45 km/s, and its central velocity shows a redshift of ~5 km/s across the shock front. The characteristics of the precursor are consistent with a cosmic-ray precursor, although the pos...

Lee, Jae-Joon; Raymond, John; Ghavamian, Parviz; Pyo, Tae-Soo; Jitsu, Akito Ta; Hayashi, Masahiko

2007-01-01

34

Supernova remnants and the ISM  

International Nuclear Information System (INIS)

Supernova remnants can reaccelerate cosmic rays and modify their distribution during the cosmic ray propagation in the galaxy. Cosmic ray observations (in particular the boron-to-carbon data) strongly limit the permitted amount of reacceleration, which is used to set an upper limit on the expansion of supernova remnants, and a lower limit on the effective density of the ISM swept up by supernova shocks. The constraint depends on the theory of cosmic ray propagation: the standard Leaky Box model requires a high effective density, > 1 -3, and is probably inconsistent with the present picture of the ISM. Modifying the Leaky Box model to include a moderate amount of weak-shock reacceleration, a self consistent solution is found, where the effective density in this solution is ? 0.1 cm-3.

1988-01-01

35

Kinematics of Shocked Molecular Gas Adjacent to the Supernova Remnant W44  

CERN Multimedia

We mapped molecular gas toward the supernova remnant W44 in the HCO+ J=1-0 line with the Nobeyama Radio Observatory 45 m telescope and in the CO J=3-2 line with the Atacama Submillimeter Telescope Experiment 10 m telescope. High-velocity emission wings were detected in both lines over the area where the radio shell of W44 overlaps the molecular cloud in the plane of the sky. We found that the average velocity distributions of the wing emission can be fitted by a uniform expansion model. The best-fit expansion velocities are 12.2+-0.3 km/s and 13.2+-0.2 km/s in HCO+ and CO, respectively. The non-wing CO J=3-2 component is also fitted by the same model with an expansion velocity of 4.7+-0.1 km/s . This component might be dominated by a post shock higher-density region where the shock velocity had slowed down. The kinetic energy of shocked molecular gas is estimated to be (3.5+-1.3)x10^{49} erg. Adding this and the energy of the previously identified HI shell, we concluded that (1.2+-0.2)x10^{50} erg has been co...

Sashida, Tomoro; Tanaka, Kunihiko; Aono, Kazuya; Matsumura, Shinji; Nagai, Makoto; Seta, Masumichi

2013-01-01

36

KINEMATICS OF SHOCKED MOLECULAR GAS ADJACENT TO THE SUPERNOVA REMNANT W44  

Energy Technology Data Exchange (ETDEWEB)

We mapped molecular gas toward the supernova remnant W44 in the HCO{sup +} J = 1-0 line with the Nobeyama Radio Observatory 45 m telescope and in the CO J = 3-2 line with the Atacama Submillimeter Telescope Experiment 10 m telescope. High-velocity emission wings were detected in both lines over the area where the radio shell of W44 overlaps with the molecular cloud in the plane of the sky. We found that the average velocity distributions of the wing emission can be fit by a uniform expansion model. The best-fit expansion velocities are 12.2 {+-} 0.3 km s{sup -1} and 13.2 {+-} 0.2 km s{sup -1} in HCO{sup +} and CO, respectively. The non-wing CO J = 3-2 component is also fit by the same model with an expansion velocity of 4.7 {+-} 0.1 km s{sup -1}. This component might be dominated by a post-shock higher-density region where the shock velocity had slowed down. The kinetic energy of the shocked molecular gas is estimated to be (3.5 {+-} 1.3) Multiplication-Sign 10{sup 49} erg. Adding this and the energy of the previously identified H I shell, we conclude that (1.2 {+-} 0.2) Multiplication-Sign 10{sup 50} erg has been converted into gas kinetic energy from the initial baryonic energy of the W44 supernova. We also found ultra-high-velocity CO J = 3-2 wing emission with a velocity width of {approx}100 km s{sup -1} at (l, b) = (+34. Degree-Sign 73, -0. Degree-Sign 47). The origin of this extremely high velocity wing is a mystery.

Sashida, Tomoro; Oka, Tomoharu; Tanaka, Kunihiko; Aono, Kazuya; Matsumura, Shinji [Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Nagai, Makoto; Seta, Masumichi [Institute of Physics, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571 (Japan)

2013-09-01

37

Kinematics of Shocked Molecular Gas Adjacent to the Supernova Remnant W44  

Science.gov (United States)

We mapped molecular gas toward the supernova remnant W44 in the HCO+ J = 1-0 line with the Nobeyama Radio Observatory 45 m telescope and in the CO J = 3-2 line with the Atacama Submillimeter Telescope Experiment 10 m telescope. High-velocity emission wings were detected in both lines over the area where the radio shell of W44 overlaps with the molecular cloud in the plane of the sky. We found that the average velocity distributions of the wing emission can be fit by a uniform expansion model. The best-fit expansion velocities are 12.2 ± 0.3 km s–1 and 13.2 ± 0.2 km s–1 in HCO+ and CO, respectively. The non-wing CO J = 3-2 component is also fit by the same model with an expansion velocity of 4.7 ± 0.1 km s–1. This component might be dominated by a post-shock higher-density region where the shock velocity had slowed down. The kinetic energy of the shocked molecular gas is estimated to be (3.5 ± 1.3) × 1049 erg. Adding this and the energy of the previously identified H I shell, we conclude that (1.2 ± 0.2) × 1050 erg has been converted into gas kinetic energy from the initial baryonic energy of the W44 supernova. We also found ultra-high-velocity CO J = 3-2 wing emission with a velocity width of ~100 km s–1 at (l, b) = (+34.°73, –0.°47). The origin of this extremely high velocity wing is a mystery.

Sashida, Tomoro; Oka, Tomoharu; Tanaka, Kunihiko; Aono, Kazuya; Matsumura, Shinji; Nagai, Makoto; Seta, Masumichi

2013-09-01

38

High Resolution Spectroscopy of Balmer-Dominated Shocks in the RCW 86, Kepler and SN 1006 Supernova Remnants  

CERN Multimedia

We report results from high resolution optical spectroscopy of three non-radiative galactic supernova remnants, RCW 86, Kepler's supernova remnant and SN 1006. We have measured the narrow component H-alpha line widths in Balmer-dominated filaments in RCW 86 and SN 1006, as well as the narrow component width in a Balmer-dominated knot in Kepler's SNR. The narrow component line widths measured in RCW 86 and Kepler's SNR show FWHM of 30-40 km/s, similar to what has been seen in other Balmer-dominated remnants. Of the remnants in our sample, SN 1006 is the fastest shock (~3000 km/s). The narrow component H-alpha and H-beta lines in this remnant have a FWHM of merely 21 km/s. Comparing the narrow component widths measured in our sample with those measured in other remnants shows that the width of the narrow component does not correlate in a simple way with the shock velocity. The implications for the pre-heating mechanism responsible for the observed line widths are discussed.

Sollerman, J; Lundqvist, P; Smith, R C; Sollerman, Jesper; Ghavamian, Parviz; Lundqvist, Peter

2003-01-01

39

The blast wave of Tycho's supernova remnant  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We use the Chandra X-ray Observatory to study the region in the Tycho supernova remnant between the blast wave and the shocked ejecta interface or contact discontinuity. This zone contains all the history of the shock-heated gas and cosmic-ray acceleration in the remnant. We present for the first ti...

Cassam-Chenai, Gamil; Hughes, John P.; Ballet, Jean; Decourchelle, Anne

40

A GENERALIZED MODEL OF NONLINEAR DIFFUSIVE SHOCK ACCELERATION COUPLED TO AN EVOLVING SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

To better model the efficient production of cosmic rays (CRs) in supernova remnants (SNRs) with the associated coupling between CR production and SNR dynamics, we have generalized an existing cr-hydro-NEI code to include the following processes: (1) an explicit calculation of the upstream precursor structure including the position-dependent flow speed, density, temperature, and magnetic field strength; (2) a momentum- and space-dependent CR diffusion coefficient; (3) an explicit calculation of magnetic field amplification; (4) calculation of the maximum CR momentum using the amplified magnetic field; (5) a finite Alfvén speed for the particle scattering centers; and (6) the ability to accelerate a superthermal seed population of CRs, as well as the ambient thermal plasma. While a great deal of work has been done modeling SNRs, most work has concentrated on either the continuum emission from relativistic electrons or ions or the thermal emission from the shock heated plasma. Our generalized code combines these elements and describes the interplay between CR production and SNR evolution, including the nonlinear coupling of efficient diffusive shock acceleration, based mainly on the work of P. Blasi and coworkers, and a non-equilibrium ionization (NEI) calculation of thermal X-ray line emission. We believe that our generalized model will provide a consistent modeling platform for SNRs, including those interacting with molecular clouds, and improve the interpretation of current and future observations, including the high-quality spectra expected from Astro-H. SNR RX J1713.7–3946 is modeled as an example.

2012-05-10

 
 
 
 
41

FISICA Integral Field Spectroscopy of the Shocked Iron Gas in the Supernova Remnant G11.2--0.3  

Science.gov (United States)

We have recently discovered strong iron line ([Fe II] (lambda)1.644 (mu)m) emission in the young supernova remnant G11.2-0.3. The iron line emission occurs at the south-eastern shell edge of G11.2-0.3, and positionally overlaps with the very strong X-ray and radio emission of the supernova remnant. The iron line emission is most likely caused by the shock acceleration of G11.2-0.3 interacting with the ambient medium. We propose to carry out JH-band integral-field spectroscopy of the two iron line clumps in G11.2-0.3 with FISICA, an image-slicing integral-field unit for FLAMINGOS, which will give us a uniquely comprehensive view of the strong shock acceleration of a SNR.

Moon, Dae-Sik; Eikenberry, Stephen S.; Koo, Bon-Chul; Raines, S. Nicholas; Gruel, Nicolas

2006-02-01

42

OH Masers and Supernova Remnants  

CERN Document Server

OH(1720 MHz) masers are created by the interaction of supernova remnants with molecular clouds. These masers are pumped by collisions in warm, shocked molecular gas with OH column densities in the range 10^{16}--10^{17} cm^{-2}. Excitation calculations suggest that inversion of the 6049 MHz OH line may occur at the higher column densities that have been inferred from main-line absorption studies of supernova remnants with the Green Bank Telescope. OH(6049 MHz) masers have therefore been proposed as a complementary indicator of remnant-cloud interaction. This motivated searches for 6049 MHz maser emission from supernova remnants using the Parkes 63 m and Effelsberg 100 m telescopes, and the Australia Telescope Compact Array. A total of forty-one remnants have been examined by one or more of these surveys, but without success. To check the accuracy of the OH column densities inferred from the single-dish observations we modelled OH absorption at 1667 MHz observed with the Very Large Array towards three supernov...

Wardle, Mark

2012-01-01

43

TWO-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS OF THE NONRESONANT, COSMIC-RAY-DRIVEN INSTABILITY IN SUPERNOVA REMNANT SHOCKS  

International Nuclear Information System (INIS)

In supernova remnants, the nonlinear amplification of magnetic fields upstream of collisionless shocks is essential for the acceleration of cosmic rays to the energy of the 'knee' at 1015.5 eV. A nonresonant instability driven by the cosmic ray current is thought to be responsible for this effect. We perform two-dimensional, particle-in-cell simulations of this instability. We observe an initial growth of circularly polarized nonpropagating magnetic waves as predicted in linear theory. It is demonstrated that in some cases the magnetic energy density in the growing waves can grow to at least 10 times its initial value. We find no evidence of competing modes, nor of significant modification by thermal effects. At late times, we observe saturation of the instability in the simulation, but the mechanism responsible is an artifact of the periodic boundary conditions and has no counterpart in the supernova-shock scenario.

2009-06-10

44

SPECTRA OF MAGNETIC FLUCTUATIONS AND RELATIVISTIC PARTICLES PRODUCED BY A NONRESONANT WAVE INSTABILITY IN SUPERNOVA REMNANT SHOCKS  

International Nuclear Information System (INIS)

We model strong forward shocks in young supernova remnants with efficient particle acceleration where a nonresonant instability driven by the cosmic ray current amplifies magnetic turbulence in the shock precursor. Particle injection, magnetic field amplification (MFA), and the nonlinear feedback of particles and fields on the bulk flow are derived consistently. The shock structure depends critically on the efficiency of turbulence cascading. If cascading is suppressed, MFA is strong, the shock precursor is stratified, and the turbulence spectrum contains several discrete peaks. These peaks, as well as the amount of MFA, should influence synchrotron X-rays, allowing observational tests of cascading and other assumptions intrinsic to the nonlinear model of nonresonant wave growth.

2009-09-20

45

What Shapes Supernova Remnants?  

CERN Document Server

Evidence has mounted that Type Ia and core-collapse (CC) supernovae (SNe) can have substantial deviations from spherical symmetry; one such piece of evidence is the complex morphologies of supernova remnants (SNRs). However, the relative role of the explosion geometry and the environment in shaping SNRs remains an outstanding question. Recently, we have developed techniques to quantify the morphologies of SNRs, and we have applied these methods to the extensive X-ray and infrared archival images available of Milky Way and Magellanic Cloud SNRs. In this proceeding, we highlight some results from these studies, with particular emphasis on SNR asymmetries and whether they arise from "nature" versus "nurture".

Lopez, Laura A

2013-01-01

46

RESOLVED SHOCK STRUCTURE OF THE BALMER-DOMINATED FILAMENTS IN TYCHO'S SUPERNOVA REMNANT: COSMIC-RAY PRECURSOR?  

International Nuclear Information System (INIS)

[en] We report on the results from H? imaging observations of the eastern limb of Tycho's supernova remnant (SN1572) using the Wide Field Planetary Camera 2 on the Hubble Space Telescope. We resolve the detailed structure of the fast, collisionless shock wave into a delicate structure of nearly edge-on filaments. We find a gradual increase of H? intensity just ahead of the shock front, which we interpret as emission from the thin (?1'') shock precursor. We find that a significant amount of the H? emission comes from the precursor and that this could affect the amount of temperature equilibration derived from the observed flux ratio of the broad and narrow H? components. The observed H? emission profiles are fit using simple precursor models, and we discuss the relevant parameters. We suggest that the precursor is likely due to cosmic rays and discuss the efficiency of cosmic-ray acceleration at this position.

2010-06-01

47

Supernova Remnant and Pulsar Wind Nebula Interactions  

CERN Document Server

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 asymmetric circumstellar medium, or pulsar velocities in the case of pulsar wind nebulae. In older remnants, asymmetric pulsar wind nebulae can result from asymmetric reverse shock flows and/or pulsar velocities.

Chevalier, R A

2003-01-01

48

Observational signatures of particle acceleration in supernova remnants  

CERN Multimedia

We evaluate the current status of supernova remnants as the sources of Galactic cosmic rays. We summarize observations of supernova remnants, covering the whole electromagnetic spectrum and describe what these obser- vations tell us about the acceleration processes by high Mach number shock fronts. We discuss the shock modification by cosmic rays, the shape and maximum energy of the cosmic-ray spectrum and the total energy budget of cosmic rays in and surrounding supernova remnants. Additionally, we discuss problems with supernova remnants as main sources of Galactic cosmic rays, as well as alternative sources.

Helder, E A; Bykov, A M; Ohira, Y; Raymond, J C; Terrier, R

2012-01-01

49

Neutron stars and supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

Recent results on the relationship between radio pulsars and supernova remnants are presented. No clear general picture has as yet emerged from the observations, although some interrelationships between pulsars or neutron stars and supernova remnants are now well documented and understood. The most interesting cases are presented and discussed.

Sieber, W.

1984-11-01

50

DUSTY BLAST WAVES OF TWO YOUNG LARGE MAGELLANIC CLOUD SUPERNOVA REMNANTS: CONSTRAINTS ON POST-SHOCK COMPRESSION  

International Nuclear Information System (INIS)

[en] We present results from mid-IR spectroscopic observations of two young supernova remnants (SNRs) in the Large Magellanic Cloud made with the Spitzer Space Telescope. We imaged SNRs B0509-67.5 and B0519-69.0 with Spitzer in 2005, and follow-up spectroscopy presented here confirms the presence of warm, shock-heated dust, with no lines present in the spectrum. We use model fits to Spitzer Infrared Spectrograph (IRS) data to estimate the density of the post-shock gas. Both remnants show asymmetries in the infrared images, and we interpret bright spots as places where the forward shock is running into material that is several times denser than elsewhere. The densities we infer for these objects depend on the grain composition assumed, and we explore the effects of differing grain porosity on the model fits. We also analyze archival XMM-Newton RGS spectroscopic data, where both SNRs show strong lines of both Fe and Si, coming from ejecta, as well as strong O lines, which may come from ejecta or shocked ambient medium. We use model fits to IRS spectra to predict X-ray O line strengths for various grain models and values of the shock compression ratio. For 0509-67.5, we find that compact (solid) grain models require nearly all O lines in X-ray spectra to originate in reverse-shocked ejecta. Porous dust grains would lower the strength of ejecta lines relative to those arising in the shocked ambient medium. In 0519-69.0, we find significant evidence for a higher than standard compression ratio of 12, implying efficient cosmic-ray acceleration by the blast wave. A compact grain model is favored over porous grain models. We find that the dust-to-gas mass ratio of the ambient medium is significantly lower than what is expected in the interstellar medium.

2011-03-01

51

New Evidence for Efficient Collisionless Heating of Electrons at the Reverse Shock of a Young Supernova Remnant  

CERN Multimedia

Although collisionless shocks are ubiquitous in astrophysics, certain key aspects of them are not well understood. In particular, the process known as collisionless electron heating, whereby electrons are rapidly energized at the shock front, is one of the main open issues in shock physics. Here we present the first clear evidence for efficient collisionless electron heating at the reverse shock of Tycho's supernova remnant (SNR), revealed by Fe-K diagnostics using high-quality X-ray data obtained by the Suzaku satellite. We detect K-beta (3p->1s) fluorescence emission from low-ionization Fe ejecta excited by energetic thermal electrons at the reverse shock front, which peaks at a smaller radius than Fe K-alpha (2p->1s) emission dominated by a relatively highly-ionized component. Comparison with our hydrodynamical simulations implies instantaneous electron heating to a temperature 1000 times higher than expected from Coulomb collisions alone. The unique environment of the reverse shock, which is propagating w...

Yamaguchi, Hiroya; Badenes, Carles; Hughes, John P; Brickhouse, Nancy S; Foster, Adam R; Patnaude, Daniel J; Petre, Robert; Slane, Patrick O; Smith, Randall K

2013-01-01

52

First Simulations of Core- Collapse Supernovae to Supernova Remnants with SNSPH  

CERN Multimedia

We present the first 3-dimensional simulations following the evolution of supernova shocks from their inception in the stellar core through the development of a supernova remnant into the Sedov phase. Our set of simulations use two different progenitors and two different conditions for the structure of the circumstellar environment. These calculations demonstrate the role that supernova instabilities (the instabilities that develop as the shock drive through the star) play in defining the structure and long-term development of instabilities in supernova remnants. We also present a first investigation of the mixing between stellar and interstellar matter as the supernova evolves into a young supernova remnant.

Ellinger, Carola I; Fryer, Christopher L; Young, Patrick A; Park, Sangwook

2013-01-01

53

Statistics of Galactic Supernova Remnants (continued)  

CERN Multimedia

Our statistics on Galactic supernova remnants (SNRs) shows that the electrons temperature ($T$) of hard X-ray and the shock waves traveling velocity ($\\upsilon$) decreases with ages ($t$) for all-sort remnants. However, the shock waves swept-up mass ($M_{su}$) of ISM increases with the age. Second, the remnant radio fluxes ($S$) at 1 GHz increase slightly with ISM electrons density ($n_0$). At last, the number distributions illustrate that the supernovae (SNe) initial kinetic energy ($E_0$), hydrogen column density ($N_H$), electrons temperature (kT) of hard X-ray, magnetic field ($B$) and the shock waves swept-up mass ($M_{su}$) of ISM mainly peaked at $(1 \\sim 10) \\times 10^{50}$ ergs, $(1 \\sim 10)\\times 10^{21}$ cm$^{-2}$, a few KeV, 100 $\\mu$G and 10$\\sim$100 $M_{\\odot}$, respectively.

Xu, Jian-Wen

2009-01-01

54

Pulsars and supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

With the recent discovery of the pulsar PSR 1951 + 22 in CTB 80, four pulsars are now known in supernova remnants (SNRs) of the plerion and composite classes. It is argued that this success rate of pulsar detections implies that young fast pulsars have long fan-beams that enable them to be seen from most directions. Based on calculations that use a pulsar luminosity model and allow for selection effects, it is suggested that the best SNRs for future pulsar searches are 3C 58, MSH 11-62, G24.7 + 0.6, and MSH 15-56. It is also concluded that the failure to detect pulsars in shell SNRs implies either that there are no pulsars in these SNRs or that the pulsars are unusually weak, possibly due to slow rotation or weak magnetic fields. 25 references.

Narayan, R.; Schaudt, K.J.

1988-02-01

55

Supernova Remnants And GLAST  

Energy Technology Data Exchange (ETDEWEB)

It has long been speculated that supernova remnants represent a major source of cosmic rays in the Galaxy. Observations over the past decade have ceremoniously unveiled direct evidence of particle acceleration in SNRs to energies approaching the knee of the cosmic ray spectrum. Nonthermal X-ray emission from shell-type SNRs reveals multi-TeV electrons, and the dynamical properties of several SNRs point to efficient acceleration of ions. Observations of TeV gamma-ray emission have confirmed the presence of energetic particles in several remnants as well, but there remains considerable debate as to whether this emission originates with high energy electrons or ions. Equally uncertain are the exact conditions that lead to efficient particle acceleration. Based on the catalog of EGRET sources, we know that there is a large population of Galactic gamma-ray sources whose distribution is similar to that of SNRs.With the increased resolution and sensitivity of GLAST, the gamma-ray SNRs from this population will be identified. Their detailed emission structure, along with their spectra, will provide the link between their environments and their spectra in other wavebands to constrain emission models and to potentially identify direct evidence of ion acceleration in SNRs. Here I summarize recent observational and theoretical work in the area of cosmic ray acceleration by SNRs, and discuss the contributions GLAST will bring to our understanding of this problem.

Slane, Patrick; /Harvard-Smithsonian Ctr. Astrophys.

2011-11-29

56

Gamma-ray Production in Supernova Remnants  

CERN Document Server

Supernova remnants are widely believed to be a principal source of galactic cosmic rays, produced by diffusive shock acceleration in the environs of the remnant's expanding shock. This review discusses recent modelling of how such energetic particles can produce gamma-rays via interactions with the remnants' ambient interstellar medium, specifically via neutral pion decay, bremsstrahlung and inverse Compton emission. Predictions that relate to the handful of associations between EGRET unidentified sources and known radio/optical/X-ray emitting remnants are summarized. The cessation of acceleration above 1 TeV - 10 TeV energies in young shell-type remnants is critical to model consistency with Whipple's TeV upper limits; these observations provide important diagnostics for theoretical models.

Baring, M G

1997-01-01

57

Turbulence and Magnetic Field Amplification in Supernova Remnants: Interactions Between A Strong Shock Wave and Multi-Phase Interstellar Medium  

CERN Document Server

We examine MHD simulations of the propagation of a strong shock wave through the interstellar two-phase medium composed of small-scale cloudlets and diffuse warm neutral medium in two-dimensional geometry. The pre-shock two-phase medium is provided as a natural consequence of the thermal instability that is expected to be ubiquitous in the interstellar medium. We show that the shock-compressed shell becomes turbulent owing to the preshock density inhomogeneity and magnetic field amplification takes place in the shell. The maximum field strength is determined by the condition that plasma beta ~ 1, which gives the field strength on the order of 1 mG in the case of shock velocity ~ 1,000 km/s. The strongly magnetized region shows filamentary and knot-like structures in two-dimensional simulations. The spatial scale of the regions with magnetic field of 1 mG in our simulation is roughly 0.05 pc which is comparable to the spatial scale of the X-ray hot spots recently discovered in supernova remnants where the magn...

Inoue, Tsuyoshi; Inutsuka, Shu-ichiro

2009-01-01

58

Particle acceleration and Tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] Particle acceleration in shock waves may be very efficient at converting bulk kinetic energy into energy density in high-energy particles. The implications for the dynamics and evolution of a Sedov-type blast wave, are investigated with particular reference to determining the energy of the supernova event associated with Tycho's supernova remnant. It is found that X-ray and radio observations favour a low efficiency of conversion of kinetic energy to high-energy particles, a supernova explosion energy of about 8 x 1043 J, and an ambient density of about 4 atom cm-3. (author)

1984-11-01

59

Resolved shock structure of the Balmer-dominated filaments in Tycho's supernova remnant: Cosmic-ray precursor?  

CERN Document Server

We report on the results from H{\\alpha} imaging observations of the eastern limb of Tycho's supernova remnant (SN1572) using the Wide Field Planetary Camera 2 on the Hubble Space Telescope. We resolve the detailed structure of the fast, collisionless shock wave into a delicate structure of nearly edge-on filaments. We find a gradual increase of H{\\alpha} intensity just ahead of the shock front, which we interpret as emission from the thin (~1") shock precursor. We find that a significant amount of the H{\\alpha} emission comes from the precursor and that this could affect the amount of temperature equilibration derived from the observed flux ratio of the broad and narrow H{\\alpha} components. The observed H{\\alpha} emission profiles are fit using simple precursor models, and we discuss the relevant parameters. We suggest that the precursor is likely due to cosmic rays and discuss the efficiency of cosmic-ray acceleration at this position.

Lee, Jae-Joon; Park, Sangwook; Blair, William P; Ghavamian, Parviz; Winkler, P F; Korreck, Kelly; 10.1088/2041-8205/715/2/L146

2010-01-01

60

Neutron stars in supernova remnants  

International Nuclear Information System (INIS)

Present knowledge and recent findings on neutron stars in supernova remnants (SNRs) are reviewed. The physics of the production of neutron stars by supernova explosions is briefly summarized, and the well-known Crab Nebula and Vela X SNRs are described. Three new discoveries of neutron stars associated with SNRs in the Galaxy and the Magellanic Clouds are discussed. These discoveries support a model of Crablike remnants which assumes that the pulsar is surrounded by two envelopes: an outer shell of fast-moving material thrown out by the supernova and a more slowly moving layer of matter from its core.

1986-01-01

 
 
 
 
61

The structure of Tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] A map of Tycho's supernova remnant (3C 10) at 2.7 GHz with a resolution of 12 x 13 arcsec is presented. The remnant shows irregularities down to a scale -3 to the SW, and about 0.1 cm-3 to the NE where there are also discrete clouds at least an order of magnitude denser. The geometrical centre (position of SN 1572) is specified. The outer edge of the radio remnant marks the shock front, and the emissivity profile requires either (a) adiabatic (Sedov) expansion with a uniform distribution of relativistic electrons, or (b) isothermal expansion with relativistic electron density varying as the thermal plasma density: in either case energy arguments show that the interstellar magnetic field is amplified by an order of magnitude over the expected post-shock value. The radio spectral index is constant (to within 0.2) over the remnant, in the frequency range 0.4 to 15 GHz. (author)

1980-01-01

62

Supernova Remnant SNR 0509 Lithograph and In Search of... Supernova Remnants Classroom Activity  

Science.gov (United States)

This Hubble Space Telescope image shows what appears to be a delicate bubble of gas floating in space. In actuality, the bubble is the visible remnant of a powerful supernova explosion called SNR 0509. The bubble was formed from gas being swept up by the expanding shock wave. The accompanying activity is a curriculum support tool designed for use as an introductory inquiry activity. In the activity, students use the images and text on this lithograph to generate questions about supernova explosions and remnants. They will conduct research to answer their questions, and create a presentation to demonstrate their understanding of the material, providing supporting evidence from their research.

2011-01-01

63

Non-linear diffusive acceleration of heavy nuclei in supernova remnant shocks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract We describe a semi-analytical approach to non-linear diffusive shock acceleration in the case in which nuclei other than protons are also accelerated. The structure of the shock is determined by the complex interplay of all nuclei, and in turn this shock structure determines the spe...

64

INFRARED STUDIES OF MOLECULAR SHOCKS IN THE SUPERNOVA REMNANT HB21. I. THERMAL ADMIXTURE OF SHOCKED H2 GAS IN THE NORTH  

International Nuclear Information System (INIS)

We present near- and mid-infrared observations on the shock-cloud interaction region in the northern part of the supernova remnant HB21, performed with the infrared camera (IRC) aboard the AKARI satellite and the wide-field infrared camera (WIRC) at the Palomar 5 m telescope. The IRC 7 ?m (S7), 11 ?m (S11), and 15 ?m (L15) band images and the WIRC H2 ? = 1 ? 0 S(1) 2.12 ?m image show similar shock-cloud interaction features. We chose three representative regions, and analyzed their IRC emissions through comparison with H2 line emissions of several shock models. The IRC colors are well explained by the thermal admixture model of H2 gas-whose infinitesimal H2 column density has a power-law relation with the temperature T, d N ? T -b dT-with n(H2)?103 cm-3, b ? 3, and N(H2; T > 100 K) ?3x1020 cm-2. The derived b value may be understood by a bow shock picture, whose shape is cycloidal (cuspy) rather than paraboloidal. However, this picture raises another issue that the bow shocks must reside within ?0.01 pc size scale, smaller than the theoretically expected. Instead, we conjectured a shocked clumpy interstellar medium picture, which may avoid the size-scale issue while explaining the similar model parameters. The observed H2 ? = 1 ? 0 S(1) intensities are a factor of ?17-33 greater than the prediction from the power-law admixture model. This excess may be attributed to either an extra component of hot H2 gas or to the effects of collisions with hydrogen atoms, omitted in our power-law admixture model, both of which would increase the population in the ? = 1 level of H2.

2009-03-10

65

Bullets in a Core Collapse Supernova Remnant The Vela Remnant  

CERN Multimedia

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 initial density contrast $\\chi \\sim 100$ relative to their surroundings are found to be rapidly fragmented and decelerated. In order to cause a pronounced protrusion on the blast wave, as observed in the Vela remnant, $\\chi \\sim 1000$ may be required. In this case, the clump should be near the inflection point in the ejecta density profile, at an ejecta velocity $\\sim 3000 \\kms $. These results apply to moderately large clumps...

Wang, C Y; Wang, Chih-Yueh; Chevalier, Roger A.

2001-01-01

66

Radioactivity and electron acceleration in supernova remnants  

International Nuclear Information System (INIS)

We argue that the decays of radioactive nuclei related to 44Ti and 56Ni ejected during supernova explosions can provide a vast pool of mildly relativistic positrons and electrons which are further accelerated to ultrarelativistic energies by reverse and forward shocks. This interesting link between two independent processes - the radioactivity and the particle acceleration - can be a clue for solution of the well known theoretical problem of electron injection in supernova remnants. In the case of the brightest radio source Cas A, we demonstrate that the radioactivity can supply adequate number of energetic electrons and positrons for interpretation of observational data provided that they are stochastically preaccelerated in the upstream regions of the forward and reverse shocks.

2011-10-15

67

Identifying Elements in Supernova Remnants  

Science.gov (United States)

This activity has students use X-ray line data to identify elements contained in supernova remnants. In groups of 2 or more, they will be given several X-ray spectra from the ASCA X-ray satellite and will be asked to determine what elements are present, using a chart listing elements and the energies of their emission lines. Following a class discussion of their results, they will be given ASTRO-E spectra of the same sources and asked to determine which elements are present. Finally, they will be given spectra from Constellation-X and asked to determine what elements are present. Students will then compare and contrast Supernova Remnant Spectral Data from the three different X-ray observatories as a class. This site contains links to the simulated spectra, chart, student worksheet, and instructions.

2007-02-02

68

Neutron Stars in Supernova Remnants and Beyond  

CERN Multimedia

We discuss a concept of off-centred cavity supernova explosion as applied to neutron star/supernova remnant associations and show how this concept could be used to preclude the anti-humane decapitating the Duck (G5.4-1.2 + G5.27-0.9) and dismembering the Swan (Cygnus Loop), as well as to search for a stellar remnant associated with the supernova remnant RCW86.

Gvaramadze, V V

2002-01-01

69

Production of Magnetic Turbulence by Cosmic Rays Drifting Upstream of Supernova Remnant Shocks  

CERN Multimedia

We present results of 2D and 3D PIC simulations of magnetic turbulence production by isotropic cosmic-ray ions drifting upstream of SNR shocks. The studies aim at testing recent predictions of a strong amplification of short wavelength non-resonant wave modes and at studying the evolution of the magnetic turbulence and its backreaction on cosmic rays. We confirm the generation of the turbulent magnetic field due to the drift of cosmic rays in the upstream plasma, but show that an oblique filamentary mode grows more rapidly than the non resonant parallel modes found in analytical theory. The growth rate of the field perturbations is much slower than is estimated using a quasi-linear approach, and the amplitude of the turbulence saturates at about dB/B~1. The backreaction of the turbulence on the particles leads to an alignment of the bulk-flow velocities of the cosmic rays and the background medium, which is an essential characteristic of cosmic-ray modified shocks. It accounts for the saturation of the instab...

Niemiec, Jacek; Stroman, Thomas; Nishikawa, and Ken-Ichi

2008-01-01

70

Spectrum of Galactic Cosmic Rays Accelerated in Supernova Remnants  

CERN Multimedia

The spectra of high-energy protons and nuclei accelerated by supernova remnant shocks are calculated taking into account magnetic field amplification and Alfvenic drift both upstream and downstream of the shock for different types of supernova remnants during their evolution. The maximum energy of accelerated particles may reach $5\\cdot10^{18}$ eV for Fe ions in Type IIb SNRs. The calculated energy spectrum of cosmic rays after propagation through the Galaxy is in good agreement with the spectrum measured at the Earth.

Ptuskin, V S; Seo, E S

2010-01-01

71

Evolution of Magnetic Fields in Supernova Remnants  

CERN Document Server

Supernova remnants (SNR) are now widely believed to be a source of cosmic rays (CRs) up to an energy of 1 PeV. The magnetic fields required to accelerate CRs to sufficiently high energies need to be much higher than can result from compression of the circumstellar medium (CSM) by a factor 4, as is the case in strong shocks. Non-thermal synchrotron maps of these regions indicate that indeed the magnetic field is much stronger, and for young SNRs has a dominant radial component while for old SNRs it is mainly toroidal. How these magnetic fields get enhanced, or why the field orientation is mainly radial for young remnants, is not yet fully understood. We use an adaptive mesh refinement MHD code, AMRVAC, to simulate the evolution of supernova remnants and to see if we can reproduce a mainly radial magnetic field in early stages of evolution. We follow the evolution of the SNR with three different configurations of the initial magnetic field in the CSM: an initially mainly toroidal field, a turbulent magnetic fie...

Schure, K M; Achterberg, A; Keppens, R

2008-01-01

72

Modeling the interaction of thermonuclear supernova remnants with circumstellar structures: The case of Tycho's supernova remnant  

CERN Document Server

The well-established Type Ia remnant of Tycho's supernova (SN 1572) reveals discrepant ambient medium density estimates based on either the measured dynamics or on the X-ray emission properties. This discrepancy can potentially be solved by assuming that the supernova remnant (SNR) shock initially moved through a stellar wind bubble, but is currently evolving in the uniform interstellar medium with a relatively low density. We investigate this scenario by combining hydrodynamical simulations of the wind-loss phase and the supernova remnant evolution with a coupled X-ray emission model, which includes non-equilibrium ionization. For the explosion models we use the well-known W7 deflagration model and the delayed detonation model that was previously shown to provide good fits to the X-ray emission of Tycho's SNR. Our simulations confirm that a uniform ambient density cannot simultaneously reproduce the dynamical and X-ray emission properties of Tycho. In contrast, models that considered that the remnant was evo...

Chiotellis, A; Schure, K M; Vink, J; Kaastra, J S

2013-01-01

73

Infrared spectroscopy and imaging of supernova remnants  

International Nuclear Information System (INIS)

We present infrared spectrophotometry and line images of the Crab Nebula and Cygnus Loop supernova remnants. In the Crab the filaments have [Fe II] 1.644 ?m/Br? of 10-50 which is similar to the shock excited [Fe II] emission from other the supernova remnants. But in the Crab the [FE II] emission is due to photoionization by power law synchrotron emission. This is an important result for understanding the infrared [Fe II] emission from galaxies because the non-thermal radiation from an active nucleus may excite the observed [Fe II] emission. H2 emission is found in two filaments, confirming the presence of dense, neutral cores. In the Cygnus Loop Faint molecular hydrogen emission has been detected in a bright optical filament. An image in the H2 line at 2.122 ?m shows that some emission lies beyond (2') the edge of the bright optical emission and is possibly associated with the non-radiative Balmer dominated shocks in this vicinity. There are also locations where H2 and bright optical line emission are coincident.

1989-01-01

74

The Outer Shock of the Oxygen-Rich Supernova Remnant G292.0+1.8: Evidence for the Interaction with the Stellar Winds from its Massive Progenitor  

CERN Document Server

We study the outer-shock structure of the oxygen-rich supernova remnant G292.0+1.8, using a deep observation with the Chandra X-ray Observatory. We measure radial variations of the electron temperature and emission measure that we identify as the outer shock propagating into a medium with a radially decreasing density profile. The inferred ambient density structure is consistent with models for the circumstellar wind of a massive progenitor star rather than for a uniform interstellar medium. The estimated wind density n_H = 0.1 ~ 0.3 cm^-3) at the current outer radius (~7.7 pc) of the remnant is consistent with a slow wind from a red supergiant (RSG) star. The total mass of the wind is estimated to be ~ 15 - 40 solar mass (depending on the estimated density range), assuming that the wind extended down to near the surface of the progenitor. The overall kinematics of G292.0+1.8 are consistent with the remnant expanding through the RSG wind.

Lee, Jae-Joon; Hughes, John P; Slane, Patrick O; Gaensler, B M; Ghavamian, Parviz; Burrows, David N

2010-01-01

75

A simple model for electron plasma heating in supernova remnants  

CERN Document Server

Context: Multiwavelength observations of supernova remnants can be explained within the framework of diffusive shock acceleration theory, which allows effective conversion of the explosion energy into cosmic rays. Although the models of nonlinear shocks describe reasonably well the nonthermal component of emission, certain issues, including the heating of the thermal electron plasma and the related X-ray emission, still remain open. Methods: Numerical solution of the equations of the Chevalier model for supernova remnant evolution, coupled with Coulomb scattering heating of the electrons. Results: The electron temperature and the X-ray thermal Bremsstrahlung emission from supernova remnants have been calculated as functions of the relevant parameters. Since only the Coulomb mechanism was considered for electron heating, the values obtained for the electron temperatures should be treated as lower limits. Results from this work can be useful to constrain model parameters for observed SNRs.

Malyshev, D; Drury, L O'C; Aharonian, F A

2010-01-01

76

Energy of Tycho's Supernova Remnant is increasing with time  

Science.gov (United States)

It is shown, using the Zeldovich integral relations, that the energy of Tycho's Supernova Remnant is strongly growing with time, approximately as t1/3. This growth can be attributed to the exothermic reactions going inside the remnant. The use of the assumption of the adiabaticity of the motion inside of the shock front, and no losses or gain of energy at the front, seems therefore unjustified.

Barenblatt, Grigory Isaakovich

2008-01-01

77

Energy of Tycho's supernova remnant is increasing with time.  

UK PubMed Central (United Kingdom)

It is shown, using the Zeldovich integral relations, that the energy of Tycho's Supernova Remnant is strongly growing with time, approximately as t(1/3). This growth can be attributed to the exothermic reactions going inside the remnant. The use of the assumption of the adiabaticity of the motion inside of the shock front, and no losses or gain of energy at the front, seems therefore unjustified.

Barenblatt GI

2008-01-01

78

Energy of Tycho's supernova remnant is increasing with time.  

Science.gov (United States)

It is shown, using the Zeldovich integral relations, that the energy of Tycho's Supernova Remnant is strongly growing with time, approximately as t(1/3). This growth can be attributed to the exothermic reactions going inside the remnant. The use of the assumption of the adiabaticity of the motion inside of the shock front, and no losses or gain of energy at the front, seems therefore unjustified. PMID:18202174

Barenblatt, Grigory Isaakovich

2008-01-17

79

Cosmic ray acceleration in young supernova remnants  

CERN Document Server

We investigate the appearance of magnetic field amplification resulting from a cosmic ray escape current in the context of supernova remnant shock waves. The current is inversely proportional to the maximum energy of cosmic rays, and is a strong function of the shock velocity. Depending on the evolution of the shock wave, which is drastically different for different circumstellar environments, the maximum energy of cosmic rays as required to generate enough current to trigger the non-resonant hybrid instability that confines the cosmic rays follows a different evolution and reaches different values. We find that the best candidates to accelerate cosmic rays to ~few PeV energies are young remnants in a dense environment, such as a red supergiant wind, as may be applicable to Cassiopeia A. We also find that for a typical background magnetic field strength of 5 microG the instability is quenched in about 1000 years, making SN1006 just at the border of candidates for cosmic ray acceleration to high energies.

Schure, K M

2013-01-01

80

CCD observations of supernova remnants  

International Nuclear Information System (INIS)

[en] The high quantum efficiency of CCD detectors makes it possible to study faint features in supernova remnants that are only barely detectable on the longest photographic exposures. The advantages of the CCD over the photographic plate is particularly striking in the near infrared where photographic emulsions are inefficient and where interstellar absorption is much reduced. The fine seeing in Hawaii allows study of much finer detail than was previously possible at other sites. Observations of the Crab nebula in subarcsecond seeing show that the H-alpha filaments in this object consist of chains of stellar or quasi-stellar knots with diameters less than about 1.0 arcsec (0.01 pc). 10 references

1986-01-01

 
 
 
 
81

Evolution of Tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] The evolution of Tycho's supernova remnant has been modeled with a numerical calculation based on a similarity solution developed by Chevalier in 1982. The new model has one important addition: a shell of matter, presumably a presupernova planetary nebula, is needed around the exploding white dwarf in order to reproduce some features in the observed morphology of the SNR. In particular, a very thin ''rim'' surrounding the main shell of the SNR cannot be reproduced without the planetary nebula. The evolution has been followed from a time of 107 s to the present epoch (1.3 x 1010 s). The results include predictions of the radial distribution of relative brightness in both X-ray and radio wavelengths

1985-01-15

82

Cosmic ray production in Historical Supernova Remnants  

International Nuclear Information System (INIS)

[en] We present the results of observations of two types of Galactic supernova remnants with the SHALON mirror Cherenkov telescope of Tien-Shan high-mountain Observatory: the shell-type supernova remnants Tycho, Cas A and IC 443; plerions Crab Nebula, 3c58(SN1181) and Geminga (probably plerion). The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (800 GeV ? 100 TeV) gamma-rays in Tycho's supernova remnant. The data obtained suggest that the very high energy gamma-ray emission in the objects being discussed is different in origin.

2013-02-01

83

Cosmic ray production in Historical Supernova Remnants  

Science.gov (United States)

We present the results of observations of two types of Galactic supernova remnants with the SHALON mirror Cherenkov telescope of Tien-Shan high-mountain Observatory: the shell-type supernova remnants Tycho, Cas A and IC 443; plerions Crab Nebula, 3c58(SN1181) and Geminga (probably plerion). The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (800 GeV - 100 TeV) gamma-rays in Tycho's supernova remnant. The data obtained suggest that the very high energy gamma-ray emission in the objects being discussed is different in origin.

Sinitsyna, V. G.; Y Sinitsyna, V.

2013-02-01

84

X-ray Observations of the Tycho Supernova Remnant  

Science.gov (United States)

In this presentation I summarize some key new findings from recent Chandra and XMM-Newton data on the remnant of the supernova (SN) observed by Tycho Brahe in 1572, which is widely believed to have been of Type Ia origin. Studies of the Tycho supernova remnant (SNR) at the current epoch address aspects of SN Ia physics, the evolution of young SNRs, and cosmic ray acceleration at high Mach-number shocks.Research on the Tycho SNR at Rutgers has been supported by Chandra grants GO3-4066X and AR5-6010X.

Hughes, John P.

2006-06-01

85

Exosat observations of the Cassiopeia A supernova remnant  

International Nuclear Information System (INIS)

The young supernova remnant Cas A has been observed with the European X-ray observatory satellite Exosat. The remnant was observed with all instruments covering the range from 0.5 to 25 KeV. It is shown here that the emission from the remnant cannot be described by a two-temperature isothermal plasma in collisional ionization equilibrium. A simple Sedov (1959) blast-wave model assuming equilibration between the electron and ion temperature but nonionization equilibrium also does not result in an acceptable fit due to strongly enhanced emission at low energies (not above 2.5 KeV). Observations made with the Exostat imaging proportional counter show that this extra emission comes from the interior regions of the remnant. The source of this low-energy flux is most probably supernova ejecta heated in a reverse shock. No evidence is found for a high temperature (not less than 20 KeV) component. 35 references.

1988-01-01

86

Extended OH(1720 MHz) Maser Emission from Supernova Remnants  

CERN Multimedia

Compact OH(1720 MHz) masers have proven to be excellent signposts for the interaction of supernova remnants with adjacent molecular clouds. Less appreciated has been the weak, extended OH(1720 MHz) emission which accompanies strong compact maser sources. Recent single-dish and interferometric observations reveal the majority of maser-emitting supernova remnants have accompanying regions of extended maser emission. Enhanced OH abundance created by the passing shock is observed both as maser emission and absorption against the strong background of the remnant. Modeling the observed OH profiles gives an estimate of the physical conditions in which weak, extended maser emission arises. I will discuss how we can realize the utility of this extended maser emission, particularly the potential to measure the strength of the post-shock magnetic field via Zeeman splitting over these large-scales.

Hewitt, J W; Wardle, M; Roberts, D A

2007-01-01

87

Evolution of Hsub(infinity)/N II in supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

The line ratio Hsub(infinity)/N II in supernova remnants has been observed to evolve as a function of the expansion velocity. This is explained by assuming that the abundance on nitrogen with respect to hydrogen in the mass ejected by the supernova explosion or, prior to it, by the supernova star, is higher than the average ambient value. The line ratio will increase as the relative abundance of nitrogen evolves towards the normal cosmic value as a result of accretion of interstellar material by the shock wave. The behavior of Hsub(infinity)/N II as a function of the radius of the supernova remnant and as a function of the (S II) line ratio lambda lambda 6717/6731 can also be explained with this model.

Bohigas, J. (Universidad Nacional Autonoma de Mexico, Mexico City)

1982-01-01

88

Particle acceleration and Tycho's supernova remnant  

Energy Technology Data Exchange (ETDEWEB)

Particle acceleration in shock waves may be very efficient at converting bulk kinetic energy into energy density in high-energy particles. The implications for the dynamics and evolution of a Sedov-type blast wave, are investigated with particular reference to determining the energy of the supernova event associated with Tycho's supernova remnant. It is found that X-ray and radio observations favour a low efficiency of conversion of kinetic energy to high-energy particles, a supernova explosion energy of about 8 x 10/sup 43/ J, and an ambient density of about 4 atom cm/sup -3/.

Heavens, A.F. (Mullard Radio Astronomy Observatory, Cambridge (UK). Cavendish Lab.)

1984-11-01

89

Relationship between supernova type and their remnants  

International Nuclear Information System (INIS)

The genetic relationship between supernovae (SNe) and supernova remnants (SNRs) is an important factor in understanding the nature of both phenomena. We present here some new results on SNe and SNRs and discuss their implications in the SN-SNR relationship.

1987-01-01

90

An infrared survey of galactic supernova remnants  

International Nuclear Information System (INIS)

Presented are preliminary results from a survey of supernova remnants (SNRs) in the data base collected by the Infrared Astronomical Satellite (IRAS). About one-third of the known galactic SNRs are visible in the IRAS data. Confusion with other sources in the galactic plane prohibits the detection of many remnants. The objects that are detected have similar spectral characteristics and temperatures, except that the three youngest remnants known, Tycho, Kepler, and Cassiopeia A, are distinctly warmer.

1988-01-01

91

Modelling the interaction of thermonuclear supernova remnants with circumstellar structures: the case of Tycho's supernova remnant  

Science.gov (United States)

The well-established Type Ia remnant of Tycho's supernova (SN 1572) reveals discrepant ambient medium-density estimates based on either the measured dynamics or the X-ray emission properties. This discrepancy can potentially be solved by assuming that the supernova remnant (SNR) shock initially moved through a stellar wind bubble, but is currently evolving in the uniform interstellar medium with a relatively low density. We investigate this scenario by combining hydrodynamical simulations of the wind-loss phase and the SNR evolution with a coupled X-ray emission model, which includes non-equilibrium ionization. For the explosion models we use the well-known W7 deflagration model and the delayed detonation model that was previously shown to provide good fits to the X-ray emission of Tycho's SNR. Our simulations confirm that a uniform ambient density cannot simultaneously reproduce the dynamical and X-ray emission properties of Tycho. In contrast, models that considered that the remnant was evolving in a dense, but small, wind bubble reproduce reasonably well both the measured X-ray emission spectrum and the expansion parameter of Tycho's SNR. Finally, we discuss possible mass-loss scenarios in the context of single- and double-degenerate models which possibly could form such a small dense wind bubble.

Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.; Kaastra, J. S.

2013-09-01

92

Modelling the interaction of thermonuclear supernova remnants with circumstellar structures: the case of Tycho's supernova remnant  

Science.gov (United States)

The well-established Type Ia remnant of Tycho's supernova (SN 1572) reveals discrepant ambient medium-density estimates based on either the measured dynamics or the X-ray emission properties. This discrepancy can potentially be solved by assuming that the supernova remnant (SNR) shock initially moved through a stellar wind bubble, but is currently evolving in the uniform interstellar medium with a relatively low density. We investigate this scenario by combining hydrodynamical simulations of the wind-loss phase and the SNR evolution with a coupled X-ray emission model, which includes non-equilibrium ionization. For the explosion models we use the well-known W7 deflagration model and the delayed detonation model that was previously shown to provide good fits to the X-ray emission of Tycho's SNR. Our simulations confirm that a uniform ambient density cannot simultaneously reproduce the dynamical and X-ray emission properties of Tycho. In contrast, models that considered that the remnant was evolving in a dense, but small, wind bubble reproduce reasonably well both the measured X-ray emission spectrum and the expansion parameter of Tycho's SNR. Finally, we discuss possible mass-loss scenarios in the context of single- and double-degenerate models which possibly could form such a small dense wind bubble.

Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.; Kaastra, J. S.

2013-10-01

93

Progenitor's signatures in Type Ia supernova remnants  

CERN Multimedia

The remnants of Type Ia supernovae can provide important clues about their progenitor-histories. We discuss two well-observed supernova remnants (SNRs) that are believed to result from a Type Ia SN and use various tools to shed light on the possible progenitor history. We find that Kepler's SNR is consistent with a symbiotic binary progenitor consisted of a white dwarf and an AGB star. Our hydrosimulations can reproduce the observed kinematic and morphological properties. For Tycho's remnant we use the characteristics of the X-ray spectrum and the kinematics to show that the ejecta has likely interacted with dense circumstellar gas.

Chiotellis, A; Schure, K M; Vink, J

2011-01-01

94

Progenitor's Signatures in Type Ia Supernova Remnants  

Science.gov (United States)

The remnants of Type Ia supernovae (SNe Ia) can provide important clues about their progenitor histories. We discuss two well-observed supernova remnants (SNRs) that are believed to have resulted from SNe Ia, and use various tools to shed light on the possible progenitor histories. We find that Kepler's SNR is consistent with a symbiotic binary progenitor consisting of a white dwarf and an AGB star. Our hydrosimulations can reproduce the observed kinematic and morphological properties. For Tycho's remnant we use the characteristics of the X-ray spectrum and kinematics to show that the ejecta has likely interacted with dense circumstellar gas.

Chiotellis, A.; Kosenko, D.; Schure, K. M.; Vink, J.

2013-01-01

95

Hydrodynamics of clouds overtaken by supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

The hydrodynamical events resulting from the interaction of a supernova remnant with a high density condensation - a cloudlet, are investigated by means of high resolution two-dimensional hydrodynamical calculations. Spherical and cylindrical cloudlets initially immersed in a constant density medium are considered. The evolution and final fate of the cloudlets is shown to depend not only on their original shape, but also on the distance to the explosion site, i.e., on whether the remnant, prior to the interaction; evolves along its Sedov or its radiative phase. However, none of the performed calculation leads to density enhancements which could clearly be related to the filamentary structure, typical of supernova remnants.

Tenorio-Tagle, G.; Rozyczka, M.

1986-02-01

96

Origin of Radially Aligned Magnetic Fields in Young Supernova Remnants  

CERN Multimedia

It has been suggested by radio observations of polarized synchrotron emissions that downstream magnetic field in some young supernova remnants are oriented radially. We study magnetic field distribution of turbulent supernova remnant driven by the Richtmyer-Meshkov instability -- in other words, the effect of rippled shock -- by using three-dimensional magnetohydrodynamics simulations. We find that the induced turbulence has radially biased anisotropic velocity dispersion that leads to a selective amplification of the radial component of the magnetic field. The Richtmyer-Meshkov instability is induced by the interaction between the shock and upstream density fluctuations. Future high-resolution polarization observation can distinguish the following candidates responsible for the upstream density fluctuations: (i) inhomogeneity caused by the cascade of large-scale turbulence in the ISM so-called the big-power-law-in-the-sky, (ii) structures generated by the Drury instability in the cosmic-ray modified shock, a...

Inoue, Tsuyoshi; Ohira, Yutaka; Yamazaki, Ryo

2013-01-01

97

X-ray emission from supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with the x-ray spectra of supernova remnants (SNRs) and, in particular, the x-ray spectra of the two young Type I SNRs SN1006 and Tycho. An extensive grid of nonequilibrium model spectra of SNRs in the adiabatic blast wave stage of evolution is computed, and numerous diagnostics of the state and composition of the blast wave plasma are plotted over parameter space. It is demonstrated that the spectrum of an adiabatic blast wave is a good approximation to several other model SNR structures in which emission is dominated by gas undergoing quasi steady state ionization near a shock front, including the one-fluid isothermal blast wave similarity solution. None of these structures appears able to account for the observed spectra of SN1006 or Tycho. A new similarity solution for the early time evolution of uniform ejecta moving into an external medium is presented. It is argued that the x-ray spectra of SN1006 and Tycho are consistent with emission mainly from a reverse shock into 1.4 solar masses of initially uniform density SN ejecta consisting of pure heavy elements, moving into a uniform medium. Satisfactory fits to the observed spectra are obtained with a two layer structure of ejecta, an outer layer of unprocessed material, and an inner layer of mixed processed heavy elements. Various salient aspects of the physics of a shock-heated pure heavy element plasma are discussed.

Sackville Hamilton, A.J.

1985-01-01

98

X-ray emission from supernova remnants  

International Nuclear Information System (INIS)

[en] This thesis deals with the x-ray spectra of supernova remnants (SNRs) and, in particular, the x-ray spectra of the two young Type I SNRs SN1006 and Tycho. An extensive grid of nonequilibrium model spectra of SNRs in the adiabatic blast wave stage of evolution is computed, and numerous diagnostics of the state and composition of the blast wave plasma are plotted over parameter space. It is demonstrated that the spectrum of an adiabatic blast wave is a good approximation to several other model SNR structures in which emission is dominated by gas undergoing quasi steady state ionization near a shock front, including the one-fluid isothermal blast wave similarity solution. None of these structures appears able to account for the observed spectra of SN1006 or Tycho. A new similarity solution for the early time evolution of uniform ejecta moving into an external medium is presented. It is argued that the x-ray spectra of SN1006 and Tycho are consistent with emission mainly from a reverse shock into 1.4 solar masses of initially uniform density SN ejecta consisting of pure heavy elements, moving into a uniform medium. Satisfactory fits to the observed spectra are obtained with a two layer structure of ejecta, an outer layer of unprocessed material, and an inner layer of mixed processed heavy elements. Various salient aspects of the physics of a shock-heated pure heavy element plasma are discussed

1985-01-01

99

Interactions between Pulsars, Pulsar Nebulae and Supernova Remnants  

CERN Document Server

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 an indication that normal pulsars avoid the O-rich remnants. In the later phases of a supernova remnant, the pulsar wind nebula is crushed by the reverse shock front. Recent simulations show that this process is unstable, which can lead to mixing of the thermal and relativistic gases, and that the pulsar nebula is easily displaced from the pulsar, which can explain the position of the Vela pulsar relative to the Vela X ...

Chevalier, R A

2002-01-01

100

Molecular clouds near supernova remnants  

International Nuclear Information System (INIS)

[en] A survey of 14 SNR's in the 4.8 GHz absorption line of H2CO shows that two of them, W28 and W44, possibly interact with molecular clouds. The interaction leads to acceleration of a part of the molceular cloud to a velocity of approximately 5 km s-1 without a significant increase in the kinetic temperature or turbulence. The apparent long-term stability of galactic molecular clouds against gravitational collapse and subsequent star formation has stimulated proposals about possible sources of external pressure, such as shocks, which could upset this equilibrium and lead to collapse. The supernova blast wave was considered as such a shock by Herbst and Assousa (1977). This proposal can be tested by observations. The interaction between a SNR and a molecular cloud may result in a disturbance of the cloud such as changing of its geometry, introducing large velocity gradients, heating etc. Spectral line mapping of the molecular clouds toward SNR's might reveal cases of SNR-molecular cloud interactions and give details of the relevant physical processes. The observations presented were aimed at (i) a search for clouds interacting with SNR's; (ii) measuring physical parameters of the disturbed molecular gas. (Auth.)

1979-08-10

 
 
 
 
101

Magnetohydrodynamic Rebound Shocks of Supernovae  

CERN Multimedia

We construct magnetohydrodynamic (MHD) similarity rebound shocks joining `quasi-static' asymptotic solutions around the central degenerate core to explore an MHD model for the evolution of random magnetic field in supernova explosions. This provides a theoretical basis for further studying synchrotron diagnostics, MHD shock acceleration of cosmic rays, and the nature of intense magnetic field in compact objects. The magnetic field strength in space approaches a limiting ratio, that is comparable to the ratio of the ejecta mass driven out versus the progenitor mass, during this self-similar rebound MHD shock evolution. The intense magnetic field of the remnant compact star as compared to that of the progenitor star is mainly attributed to both the gravitational core collapse and the radial distribution of magnetic field.

Lou, Yu-Qing

2007-01-01

102

The Kinematics of Kepler's Supernova Remnant as Revealed by Chandra  

Science.gov (United States)

I have determined the expansion of the supernova remnant of SN 1604 (Kepler's supernova) based on archival Chandra ACIS-S observations made in 2000 and 2006. The measurements were done in several distinct energy bands, and were made for the remnant as a whole, and for six individual sectors. The average expansion parameter indicates that the remnant expands on average as r~t0.5, but there are significant differences in different parts of the remnant: the bright northwestern part expands as r~t0.35, whereas the rest of the remnant's expansion shows an expansion r~t0.6. The latter is consistent with an explosion in which the outer part of the ejecta has a negative power law slope for density (?~v-n) of n=7, or with an exponential density profile [?~exp(-v/ve)]. The expansion parameter in the southern region, in conjunction with the shock radius, indicates a rather low value (speed r~t0.7, corresponding to a shock velocity of v=4200 km s-1, for a distance to SN 1604 of 4 kpc. This is consistent with the idea that X-ray synchrotron emission requires shock velocities in excess of ~2000 km s-1. The X-ray-based expansion measurements reported are consistent with results based on optical and radio measurements but disagree with previous X-ray measurements based on ROSAT and Einstein observations.

Vink, Jacco

2008-12-01

103

OH (1720 MHz) Masers and Mixed-Morphology Supernova Remnants  

CERN Multimedia

Radio surveys of supernova remnants (SNRs) in the Galaxy have uncovered 19 SNRs accompanied by OH maser emission at 1720 MHz. This unusual class of maser sources is suggested to be produced behind a shock front from the expansion of a supernova remnant running into a molecular cloud. An important ingredient of this model is that X-ray emission from the remnant enhances the production of OH molecule. The role of X-ray emission from maser emitting (ME) SNRs is investigated by comparing the X-ray induced ionization rate with theory. One aspect of this model is verified: there is a strong association between maser emitting and mixed-morphology (MM) or thermal composite SNRs --center-filled thermal X-ray emission surrounded by shell-like radio morphology. We also present ROSAT and ASCA observations of two maser emitting SNRs: G21.8--0.6 (Kes 69) and G357.7--0.1 (Tornado).

Yusef-Zadeh, F; Rho, J; Sakano, M

2003-01-01

104

Rayleigh-Taylor Instabilities in Type Ia Supernova Remnants undergoing Cosmic-Ray Particle Acceleration - Low Adiabatic Index Solutions  

CERN Multimedia

This study investigates the evolution of Rayleigh-Taylor (R-T) instabilities in Type Ia supernova remnants owing to a low adiabatic index $\\gamma$, where $\\gamma$=1.2. As a result of the age of the remnant, the unstable gas cannot extend sufficiently far to produce the metal-enriched filaments of ejecta material close to the periphery of Tycho's supernova remnant. The dynamical properties of Tycho's remnant reveal that the injection of cosmic rays is too weak to alter the shock structure. Even if efficient acceleration of cosmic rays at the shock suffice, significantly enhanced mixing is not expected in Type Ia supernova remnants.

Wang, Chih-Yueh

2010-01-01

105

X-ray halos around supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

The results are reported of an Einstein Observatory imaging proportional counter investigation of the X-ray halos of the four brightest young Galactic supernova remnants: the Crab Nebula, Cas A, Tycho's, and Kepler's supernova remnant. It is found that the size, shape, and rough intensity of each of these sources are consistent with the measured properties of the X-ray halos of compact Galactic X-ray sources, and as such are consistent with an origin due solely to the scattering of X-rays by interstellar grains. 45 references.

Mauche, C.W.; Gorenstein, P.

1989-01-01

106

X-ray halos around supernova remnants  

International Nuclear Information System (INIS)

[en] The results are reported of an Einstein Observatory imaging proportional counter investigation of the X-ray halos of the four brightest young Galactic supernova remnants: the Crab Nebula, Cas A, Tycho's, and Kepler's supernova remnant. It is found that the size, shape, and rough intensity of each of these sources are consistent with the measured properties of the X-ray halos of compact Galactic X-ray sources, and as such are consistent with an origin due solely to the scattering of X-rays by interstellar grains. 45 references

1989-01-01

107

Imagery and spectroscopy of supernova remnants and H-2 regions  

Energy Technology Data Exchange (ETDEWEB)

Research activities relating to supernova remnants were summarized. The topics reviewed include: progenitor stars of supernova remnants, UV/optical/radio/X-ray imagery of selected regions in the Cygnus Loop, UV/optical spectroscopy of the Cygnus Loop spur, and extragalactic supernova remnant spectra.

Dufour, R.J.

1984-06-01

108

X-Ray Measured Dynamics of Tycho's Supernova Remnant  

CERN Document Server

We present X-ray proper-motion measurements of the forward shock and reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of archival Chandra data taken in 2000, 2003, and 2007. We find that the proper motion of the edge of the remnant (i.e., the forward shock and protruding ejecta knots) varies from 0".20 yr^{-1} (expansion index m=0.33, where R = t^m) to 0".40 yr^{-1} (m=0.65) with azimuthal angle in 2000-2007 measurements, and 0".14 yr^{-1} (m=0.26) to 0".40 yr^{-1} (m=0.65) in 2003-2007 measurements. The azimuthal variation of the proper motion and the average expansion index of ~0.5 are consistent with those derived from radio observations. We also find proper motion and expansion index of the reverse-shocked ejecta to be 0".21-0".31 yr^{-1} and 0.43-0.64, respectively. From a comparison of the measured m-value with Type Ia supernova evolutionary models, we find a pre-shock ambient density around the remnant of <~0.2 cm^{-3}.

Katsuda, Satoru; Hughes, John P; Hwang, Una; Yamaguchi, Hiroya; Hayato, Asami; Mori, Koji; Tsunemi, Hiroshi

2010-01-01

109

X-RAY MEASURED DYNAMICS OF TYCHO'S SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

[en] We present X-ray proper-motion measurements of the forward shock and reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of archival Chandra data taken in 2000, 2003, and 2007. We find that the proper motion of the edge of the remnant (i.e., the forward shock and protruding ejecta knots) varies from 0.''20 yr-1 (expansion index m = 0.33, where R = tm ) to 0.''40 yr-1 (m = 0.65) with azimuthal angle in 2000-2007 measurements, and 0.''14 yr-1 (m = 0.26) to 0.''40 yr-1 (m = 0.65) in 2003-2007 measurements. The azimuthal variation of the proper motion and the average expansion index of ?0.5 are consistent with those derived from radio observations. We also find proper motion and expansion index of the reverse-shocked ejecta to be 0.''21-0.''31 yr-1 and 0.43-0.64, respectively. From a comparison of the measured m-value with Type Ia supernova evolutionary models, we find a pre-shock ambient density around the remnant of ?-3.

2010-02-01

110

CARBON MONOXIDE IN THE CASSIOPEIA A SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

We report the likely detection of near-infrared 2.29 ?m first overtone carbon monoxide (CO) emission from the young supernova (SN) remnant Cassiopeia A (Cas A). The continuum-subtracted CO filter map reveals CO knots within the ejecta-rich reverse shock. We compare the first overtone CO emission with that found in the well studied supernova SN 1987A and find ?30 times less CO in Cas A. The presence of CO suggests that molecule mixing is small in the SN ejecta and that astrochemical processes and molecule formation may continue at least ?300 yr after the initial explosion.

2009-03-01

111

Supernova Remnants, Cosmic Rays, and GLAST  

Energy Technology Data Exchange (ETDEWEB)

The shock waves of supernova remnants (SNRs) are the traditional sources of Galactic cosmic rays, at least up to about 3000 TeV (the 'knee' energy in the cosmic-ray spectrum). In the last decade or so, X-ray observations have confirmed in a few SNRs the presence of synchrotron-X-ray-emitting electrons with energies of order 100 TeV. TeV photons from SNRs have been observed with ground-based air Cerenkov telescopes as well, but it is still unclear whether they are due to hadronic processes (inelastic p-p scattering of cosmic-ray protons from thermal gas, with secondary neutral pions decaying to gamma rays), or to leptonic processes (inverse-Compton upscattering of cosmic microwave background photons, or bremsstrahlung). The spatial structure of synchrotron X-rays as observed with the Chandra X-ray Observatory suggests the remarkable possibility that magnetic fields are amplified by orders of magnitude in strong shock waves. The electron spectra inferred from X-rays reach 100 TeV, but at that energy are cutting off steeply, well below the 'knee' energy. Are the cutoff processes due only to radiative losses so that ion spectra might continue unsteepened? Can we confirm the presence of energetic ions in SNRs at all? Are typical SNRs capable of supplying the pool of Galactic cosmic rays? Is strong magnetic-field amplification a property of strong astrophysical shocks in general? These major questions require the next generation of observational tools. I shall outline the theoretical and observational framework of particle acceleration to high energies in SNRs, and shall describe how GLAST will advance this field.

Reynolds, Steve (North Carolina State University)

2006-02-13

112

Supernova remnants and the Exosat satellite  

Energy Technology Data Exchange (ETDEWEB)

Exosat was launched on 26 May 1983 and operated for almost three years. A wide variety of X-ray emitting objects were observed, including the remnants of exploded stars. The study of these supernova remnants allows astronomers to examine the operation of scientific laws and theorems under physical conditions that are not reproducible on Earth. Exosat's payload of scientific instruments was well suited to this task and the data obtained have augmented our understanding of supernova remnants themselves, their interaction with the nearby interstellar medium, and the evolution of the Galaxy as well as the physical processes that are important both in very rarified, hot plasmas and the environment of magnetised neutron stars.

Smith, A. (European Space Research and Technology Centre, Noordwijk (NL))

1990-05-01

113

Morphology of synchrotron emission in young supernova remnants  

CERN Multimedia

In the framework of test-particle and cosmic-ray modified hydrodynamics, we calculate synchrotron emission radial profiles in young ejecta-dominated supernova remnants (SNRs) evolving in an ambient medium which is uniform in density and magnetic field. We find that, even without any magnetic field amplification by Raleigh-Taylor instabilities, the radio synchrotron emission peaks at the contact discontinuity because the magnetic field is compressed and is larger there than at the forward shock. The X-ray synchrotron emission sharply drops behind the forward shock as the highest energy electrons suffer severe radiative losses.

Cassam-Chenai, G; Ballet, J; Ellison, D C; Cassam-Chenai, Gamil; Decourchelle, Anne; Ballet, Jean; Ellison, Donald C.

2005-01-01

114

Stochastic Particle Acceleration in Shell-Type Supernova Remnants  

CERN Multimedia

We study the stochastic particle acceleration by fast mode waves in the downstream of weakly magnetized collisionless astrophysical shocks. The particle acceleration is most efficient in a supersonic dissipative layer, and the model characteristics are determined by the shock speed, density, magnetic field, and turbulence decay length. The accelerated electrons in shell-type supernova remnants (SNRs) explain observations of SNRs RX J1713.7-3946 and RX J0852.0-4622. Future observations in the hard X-rays with the HXMT and NuSTAR and gamma-rays with the GLAST can test this model.

Liu, Siming; Fryer, Christopher L; Wang, Jian-Min; Li, Hui

2008-01-01

115

Far Ultraviolet Spectral Images of the Vela Supernova Remnant  

CERN Multimedia

We present far-ultraviolet (FUV) spectral-imaging observations of the Vela supernova remnant (SNR), obtained with the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR) instrument, also known as FIMS. The Vela SNR extends 8 degrees in the FUV and its global spectra are dominated by shock-induced emission lines. We find that the global FUV line luminosities can exceed the 0.1-2.5 keV soft X-ray luminosity by an order of magnitude. The global O VI:C III ratio shows that the Vela SNR has a relatively large fraction of slower shocks compared with the Cygnus Loop.

Nishikida, K; Feuerstein, W M; Jin, H; Korpela, E J; Lee, D H; Min, K W; Sankrit, R; Seon, K I; Shinn, J H; Yuk, I S

2006-01-01

116

Fermi LAT Observations of Supernova Remnants Interacting with Molecular Clouds  

CERN Multimedia

We report the detection of gamma-ray emission coincident with four supernova remnants (SNRs) using data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. G349.7+0.2, CTB 37A, 3C 391 and G8.7-0.1 are supernova remnants known to be interacting with molecular clouds, as evidenced by observations of hydroxyl (OH) maser emission at 1720 MHz in their directions. SNR shocks are expected to be sites of cosmic rays acceleration, and clouds of dense material can provide effective targets for production of gamma-rays from pion-decay. The observations reveal unresolved sources in the direction of G349.7+0.2, CTB 37A and 3C 391, and a possibly extended source coincident with G8.7-0.1, all with significance levels greater than 10 sigma.

Castro, Daniel

2010-01-01

117

NON-MAXWELLIAN H? PROFILES IN TYCHO'S SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

[en] The broad components of the H? lines in most non-radiative shocks can be fit with single-Gaussian components. We have obtained a high-quality spectrum of a position in Tycho's supernova remnant with the MMT and Blue Channel Spectrograph which shows, for the first time, that a single Gaussian does not provide an acceptable fit. This implies that a single temperature Maxwellian particle velocity distribution cannot produce the emission. Possible alternative explanations are explored, including multiple shocks along the line of sight, a pickup ion contribution, a non-thermal tail (Kappa distribution), emission from a precursor in a cosmic ray modified shock, or turbulence. An Hubble Space Telescope image shows a bright knot that might account for a low temperature contribution, and all the possibilities probably contribute at some level. We discuss the implications of each explanation for the shock parameters and physics of collisionless shocks, but cannot conclusively rule out any of them.

2010-04-01

118

Dust in Historical Galactic Type Ia Supernova Remnants with Herschel  

CERN Document Server

The origin of interstellar dust in galaxies is poorly understood, particularly the relative contributions from supernovae and the cool stellar winds of low-intermediate mass stars. Here, we present Herschel PACS and SPIRE photometry at 70-500um of the historical young supernova remnants: Kepler and Tycho; both thought to be the remnants of Type Ia explosion events. We detect a warm dust component in Kepler's remnant with T = 82K and mass 0.0031 M\\odot; this is spatially coincident with thermal X-ray emission optical knots and filaments, consistent with the warm dust originating in the circumstellar material swept up by the primary blast wave of the remnant. Similarly for Tycho's remnant, we detect warm dust at 90K with mass 0.0086 M\\odot. Comparing the spatial distribution of the warm dust with X-rays from the ejecta and swept-up medium, and Ha emission arising from the post-shock edge, we show that the warm dust is swept up interstellar material. We find no evidence of a cool (25-50 K) component of dust with...

Gomez, H L; Nozawa, T; Krause, O; Gomez, E L; Matsuura, M; Barlow, M J; Besel, M -A; Dunne, L; Gear, W K; Hargrave, P; Henning, Th; Ivison, R J; Sibthorpe, B; Swinyard, B M; Wesson, R

2011-01-01

119

Extremely Fast Acceleration of Cosmic Rays in a Supernova Remnant  

Energy Technology Data Exchange (ETDEWEB)

Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays. Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of theSNRRXJ1713.723946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100. The X-ray variability also implies that we have witnessed the ongoing shock-acceleration of electrons in real time. Independently, broadband X-ray spectrometric measurements of RXJ1713.723946 indicate that electron acceleration proceeds in the most effective ('Bohm-diffusion') regime. Taken together, these two results provide a strong argument for acceleration of protons and nuclei to energies of 1 PeV (10{sup 15} eV) and beyond in young supernova remnants.

Uchiyama, Y.; Aharonian, F.A.; Tanaka, T.; Takahashi, T.; Maeda, Y.; /JAERI, Tokai /Dublin Inst. /Heidelberg, Max Planck Inst. /SLAC

2007-10-23

120

A Supernova Remnant Collision with a Stellar Wind  

CERN Multimedia

Numerical simulations of the interaction between supernova ejecta and a stellar wind are presented. We follow the temporal evolution of the shock fronts that are formed through such an interaction and determine the velocities, temperatures and densities. We model the X-ray emission from the SNR-stellar wind collision region and we compare it with recent results from X-ray observations carried out with the Chandra satellite of the SMC supernova remnant SNR 0057-7226 which could be interacting with the wind of the Wolf-Rayet system HD 5980. The simulations predict the presence of shell-like regions of enhanced X-ray emission which are consistent with the presence of X-ray emitting arcs in the Chandra image. Also the observed X-ray luminosity is comparable to the X-ray luminosities we obtain from the simulations for a supernova with an initial energy in the (1-5)E50 erg range.

Velazquez, P F; Raga, A C; Velazquez, Pablo F.; Koenigsberger, Gloria; Raga, Alejandro C.

2003-01-01

 
 
 
 
121

Central Compact Objects in Supernova Remnants  

CERN Document Server

There are point-like sources in central regions of several supernova remnants which have not been detected outside the X-ray range. The X-ray spectra of these Central Compact Objects (CCOs) have thermal components with blackbody temperatures of 0.2-0.5 keV and characteristic sizes of 0.3-3 km. Most likely, the CCOs are neutron stars born in supernova explosions. We overview their observational properties, emphasizing the Chandra data, and compare them with magnetars.

Pavlov, G G; Teter, M A; Pavlov, George G.; Sanwal, Divas; Teter, Marcus A.

2003-01-01

122

Nonuniform abundances in young supernova remnants  

International Nuclear Information System (INIS)

[en] In a young SNR, the possible variation in composition should not be ignored in interpreting observational data. As an example, it is explicitly shown that the Becker et al. observations of Tycho's supernova remnant with HEAO 2 (Einstein) Observatory are consistent with a previously calculated numerical model of a Type I supernova explosion incorporating decay of 56Ni. In young SNRs it may be possible to detect directly the compositions characteristic of the layered structure of the presupernova, not merely the average abundance

1980-08-15

123

Nonuniform abundances in young supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

In a young SNR, the possible variation in composition should not be ignored in interpreting observational data. As an example, it is explicitly shown that the Becker et al. observations of Tycho's supernova remnant with HEAO 2 (Einstein) Observatory are consistent with a previously calculated numerical model of a Type I supernova explosion incorporating decay of /sup 56/Ni. In young SNRs it may be possible to detect directly the compositions characteristic of the layered structure of the presupernova, not merely the average abundance.

Arnett, W.D.

1980-08-15

124

A search for young Galactic supernova remnants  

Science.gov (United States)

A sample of eight small-diameter radio sources has been selected from the Molonglo Galactic Plane Survey (MGPS) as candidates for young Galactic supernova remnants. The sources have been identified in the IRAS and Midcourse Space Experiment infrared data bases and imaged in the H107? radio recombination line (RRL) using the Australia Telescope Compact Array (ATCA). Seven of the sources display high ratios of infrared-to-radio-continuum flux density and/or detectable RRLs and are almost certainly H II regions. One source (G282.8-1.2) is identified as a possible new young Galactic supernova remnant, based on its relatively weak infrared emission, steep radio spectrum, and possible X-ray emission. The adopted method for distinguishing thermal and non-thermal Galactic radio sources seems promising and could be fruitfully applied to more than 100 small-diameter sources listed in the MGPS.

Misanovic, Zdenka; Cram, Lawrence; Green, Anne

2002-09-01

125

X-rays from Supernova Remnants  

CERN Multimedia

A summary of X-ray observations of supernova remnants is presented including the explosion fragment A of the Vela SNR, Tycho, N132D, RX J0852-4622, the Crab Nebula and the 'bulls eye', and SN 1987A, high-lighting the progress made with Chandra and XMM-Newton and touching upon the questions which arise from these observations and which might inspire future research.

Aschenbach, B

2002-01-01

126

AZIMUTHAL DENSITY VARIATIONS AROUND THE RIM OF TYCHO's SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

[en] Spitzer images of Tycho's supernova remnant in the mid-infrared reveal limb-brightened emission from the entire periphery of the shell and faint filamentary structures in the interior. As with other young remnants, this emission is produced by dust grains, warmed to ?100 K in the post-shock environment by collisions with energetic electrons and ions. The ratio of the 70 to 24 ?m fluxes is a diagnostic of the dust temperature, which in turn is a sensitive function of the plasma density. We find significant variations in the 70/24 flux ratio around the periphery of Tycho's forward shock, implying order-of-magnitude variations in density. While some of these are likely localized interactions with dense clumps of the interstellar medium (ISM), we find an overall gradient in the ambient density surrounding Tycho, with densities 3-10 times higher in the northeast than in the southwest. This large density gradient is qualitatively consistent with the variations in the proper motion of the shock observed in radio and X-ray studies. Overall, the mean ISM density around Tycho is quite low (?0.1-0.2 cm–3), consistent with the lack of thermal X-ray emission observed at the forward shock. We perform two-dimensional hydrodynamic simulations of a Type Ia supernova expanding into a density gradient in the ISM, and find that the overall round shape of the remnant is still easily achievable, even for explosions into significant gradients. However, this leads to an offset of the center of the explosion from the geometric center of the remnant of up to 20%, although lower values of 10% are preferred. The best match with hydrodynamical simulations is achieved if Tycho is located at a large (3-4 kpc) distance in a medium with a mean preshock density of ?0.2 cm–3. Such preshock densities are obtained for highly (?> 50%) porous ISM grains.

2013-06-20

127

Azimuthal Density Variations around the Rim of Tycho's Supernova Remnant  

Science.gov (United States)

Spitzer images of Tycho's supernova remnant in the mid-infrared reveal limb-brightened emission from the entire periphery of the shell and faint filamentary structures in the interior. As with other young remnants, this emission is produced by dust grains, warmed to ~100 K in the post-shock environment by collisions with energetic electrons and ions. The ratio of the 70 to 24 ?m fluxes is a diagnostic of the dust temperature, which in turn is a sensitive function of the plasma density. We find significant variations in the 70/24 flux ratio around the periphery of Tycho's forward shock, implying order-of-magnitude variations in density. While some of these are likely localized interactions with dense clumps of the interstellar medium (ISM), we find an overall gradient in the ambient density surrounding Tycho, with densities 3-10 times higher in the northeast than in the southwest. This large density gradient is qualitatively consistent with the variations in the proper motion of the shock observed in radio and X-ray studies. Overall, the mean ISM density around Tycho is quite low (~0.1-0.2 cm-3), consistent with the lack of thermal X-ray emission observed at the forward shock. We perform two-dimensional hydrodynamic simulations of a Type Ia supernova expanding into a density gradient in the ISM, and find that the overall round shape of the remnant is still easily achievable, even for explosions into significant gradients. However, this leads to an offset of the center of the explosion from the geometric center of the remnant of up to 20%, although lower values of 10% are preferred. The best match with hydrodynamical simulations is achieved if Tycho is located at a large (3-4 kpc) distance in a medium with a mean preshock density of ~0.2 cm-3. Such preshock densities are obtained for highly (gsim 50%) porous ISM grains.

Williams, Brian J.; Borkowski, Kazimierz J.; Ghavamian, Parviz; Hewitt, John W.; Mao, S. Alwin; Petre, Robert; Reynolds, Stephen P.; Blondin, John M.

2013-06-01

128

Modelling neutrino and gamma-ray fluxes in supernova remnants  

International Nuclear Information System (INIS)

Supernova remnants (SNRs) are believed to accelerate charged particles by diffusive shock acceleration (DSA) and to produce the majority of galactic cosmic rays, at least up to the 'knee' at 3-1015 electron volts. In the framework of a hydrodynamic self-similar simulation of the evolution of young supernova remnants, its interaction with the ambient matter as well as the microwave and infrared background is studied. The photon spectra resulting from synchrotron and inverse Compton emission as well as from hadronic processes are calculated, as are the accompanying neutrino fluxes. Applying this method to the particular case of the SNR RXJ-1713, 7-3946, we find that its TeV emission can in principle be explained by pion decay if the ambient density is assumed to grow with increasing distance from the centre. The neutrino flux associated with this hadronic model is of a magnitude that may be detectable by a cubic-kilometre sized deep-sea neutrino telescope in the northern hemisphere. In this poster, a description of the supernova remnant simulation is given together with the results concerning RXJ-1713.

2008-11-01

129

Supernova Remnant Relevant Laser-plasma Experiments  

International Nuclear Information System (INIS)

Laboratory astro-plasma physics experiments are being designed to advance both our astrophysics and plasma physics knowledge. With current laser technology, target design and diagnostics, it is now possible to reproduce and measure the conditions of temperature and pressure usually met in extreme stellar environments. Coupled with scaled plasma physics it is possible to simulate certain aspects of astrophysical phenomena in the laser laboratory. The focus is on experiments designed to address key aspects of the plasma physics occurring in supernova remnants. In this approach ideal magneto-hydrodynamics is applied to the supernova remnant and then scaled. Matching dimensionless parameters in a laboratory experiment enables the simulation of complex astro-plasma systems offering the advantage of repeated, detailed measurements and the flexibility to alter the input conditions. Work at York has centered on developing a collisionless plasma experiment. The experiment involves a magnetic field, and two laser-exploded plasmas to make possible a laboratory study of the interaction between a supernova remnant and the interstellar medium. These experiments and the analysis are discussed.

2004-10-20

130

On the relationship between pulsars and supernova remnants  

International Nuclear Information System (INIS)

It is proposed that single stars in the mass range 4-6.5M., that explode as supernovae of Type I, are totally disrupted by the explosion and form shell-type remnants. More massive single stars which explode as supernovae of Type II also give rise to shell-type remnants, but in this case a neutron star or a black hole is left behind. The first supernova explosion in a close binary also gives rise to a shell-type supernova remnant. The Crab-like filled-centre supernova remnants are formed by the second supernova explosion in a close binary. The hybrid supernova remnants, consisting of a filled centre surrounded by a shell, are formed if there is an active neutron star inside the shell. (author).

1981-01-01

131

Future GLAST observations of Supernova remnants and Pulsar Wind Nebulae  

CERN Multimedia

Shell-type Supernova remnants (SNRs) have long been known to harbour a population of ultra-relativistic particles, accelerated in the Supernova shock wave by the mechanism of diffusive shock acceleration. Experimental evidence for the existence of electrons up to energies of ~100 TeV was first provided by the detection of hard X-ray synchrotron emission as e.g. in the shell of the young SNR SN1006. Furthermore using theoretical arguments shell-type Supernova remnants have long been considered as the main accelerator of protons - Cosmic rays - in the Galaxy; definite proof of this process is however still missing. Pulsar Wind Nebulae (PWN) - diffuse structures surrounding young pulsars - are another class of objects known to be a site of particle acceleration in the Galaxy, again through the detection of hard synchrotron X-rays such as in the Crab Nebula. Gamma-rays above 100 MeV provide a direct access to acceleration processes. The GLAST Large Area telescope (LAT) will be operating in the energy range betwee...

Funk, S

2007-01-01

132

Future GLAST Observations of Supernova Remnants And Pulsar Wind Nebulae  

Energy Technology Data Exchange (ETDEWEB)

Shell-type Supernova remnants (SNRs) have long been known to harbour a population of ultra-relativistic particles, accelerated in the Supernova shock wave by the mechanism of diffusive shock acceleration. Experimental evidence for the existence of electrons up to energies of 100 TeV was first provided by the detection of hard X-ray synchrotron emission as e.g. in the shell of the young SNR SN1006. Furthermore using theoretical arguments shell-type Supernova remnants have long been considered as the main accelerator of protons - Cosmic rays - in the Galaxy; definite proof of this process is however still missing. Pulsar Wind Nebulae (PWN) - diffuse structures surrounding young pulsars - are another class of objects known to be a site of particle acceleration in the Galaxy, again through the detection of hard synchrotron X-rays such as in the Crab Nebula. Gamma-rays above 100 MeV provide a direct access to acceleration processes. The GLAST Large Area telescope (LAT) will be operating in the energy range between 30 MeV and 300 GeV and will provide excellent sensitivity, angular and energy resolution in a previously rather poorly explored energy band. We will describe prospects for the investigation of these Galactic particle accelerators with GLAST.

Funk, S.; /KIPAC, Menlo Park

2007-09-26

133

Simulation of the growth of the 3D Rayleigh-Taylor instability in Supernova Remnants using an expanding reference frame  

CERN Multimedia

Context: The Rayleigh-Taylor instabilities generated by the deceleration of a supernova remnant during the ejecta-dominated phase are known to produce finger-like structures in the matter distribution which modify the geometry of the remnant. The morphology of supernova remnants is also expected to be modified when efficient particle acceleration occurs at their shocks. Aims: The impact of the Rayleigh-Taylor instabilities from the ejecta-dominated to the Sedov-Taylor phase is investigated over one octant of the supernova remnant. We also study the effect of efficient particle acceleration at the forward shock on the growth of the Rayleigh-Taylor instabilities. Methods: We modified the Adaptive Mesh Refinement code RAMSES to study with hydrodynamic numerical simulations the evolution of supernova remnants in the framework of an expanding reference frame. The adiabatic index of a relativistic gas between the forward shock and the contact discontinuity mimics the presence of accelerated particles. Results: The ...

Fraschetti, Federico; Ballet, Jean; Decourchelle, Anne

2010-01-01

134

Cosmic ray acceleration and escape from supernova remnants  

CERN Document Server

Galactic cosmic ray (CR) acceleration to the knee in the spectrum at a few PeV is only possible if the magnetic field ahead of a supernova remnant (SNR) shock is strongly amplified by CR escaping the SNR. A model formulated in terms of the electric charge carried by escaping CR predicts the maximum CR energy and the energy spectrum of CR released into the surrounding medium. We find that historical SNR such as Cas A, Tycho and Kepler may be expanding too slowly to accelerate CR to the knee at the present time.

Bell, AR; Reville, B; Giacinti, G

2013-01-01

135

Cosmic-ray acceleration and escape from supernova remnants  

Science.gov (United States)

Galactic cosmic-ray (CR) acceleration to the knee in the spectrum at a few PeV is only possible if the magnetic field ahead of a supernova remnant (SNR) shock is strongly amplified by CRs escaping the SNR. A model formulated in terms of the electric charge carried by escaping CRs predicts the maximum CR energy and the energy spectrum of CRs released into the surrounding medium. We find that historical SNRs such as Cas A, Tycho and Kepler may be expanding too slowly to accelerate CRs to the knee at the present time.

Bell, A. R.; Schure, K. M.; Reville, B.; Giacinti, G.

2013-05-01

136

Nonthermal Emission from a Supernova Remnant in a Molecular Cloud  

CERN Document Server

In evolved supernova remnants (SNRs) interacting with molecular clouds, such as IC 443, W44, and 3C391, a highly inhomogeneous structure consisting of a forward shock of moderate Mach number, a cooling layer, a dense radiative shell and an interior region filled with hot tenuous plasma is expected. We present a kinetic model of nonthermal electron injection, acceleration and propagation in that environment and find that these SNRs are efficient electron accelerators and sources of hard X- and gamma-ray emission. The energy spectrum of the nonthermal electrons is shaped by the joint action of first and second order Fermi acceleration in a turbulent plasma with substantial Coulomb losses. Bremsstrahlung, synchrotron, and inverse Compton radiation of the nonthermal electrons produce multiwavelength photon spectra in quantitative agreement with the radio and the hard emission observed by ASCA and EGRET from IC 443. We distinguish interclump shock wave emission from molecular clump shock wave emission accounting f...

Bykov, A M; Ellison, D C; Uvarov, Yu A; Uvarov, Yu.A.

2000-01-01

137

Kepler's Supernova Remnant: The view at 400 Years  

CERN Document Server

October 2004 marks the 400th anniversary of the sighting of SN 1604, now marked by the presence of an expanding nebulosity known as Kepler's supernova remnant. Of the small number of remnants of historical supernovae, Kepler's remnant remains the most enigmatic. The supernova type, and hence the type of star that exploded, is still a matter of debate, and even the distance to the remnant is uncertain by more than a factor of two. As new and improved multiwavength observations become available, and as the time baseline of observations gets longer, Kepler's supernova remnant is slowly revealing its secrets. I review recent and current observations of Kepler's supernova remnant and what they indicate about this intriguing object.

Blair, W P

2004-01-01

138

Particle acceleration at supernova shocks in young stellar clusters.  

Science.gov (United States)

We briefly discuss models of energetic particle acceleration by supernova shock in active starforming regions at different stages of their evolution. Strong shocks may strongly amplify magnetic fields due to cosmic ray driven instabilities. We discuss the magnetic field amplification emphasizing the role of the long-wavelength instabilities. Supernova shock propagating in the vicinity of a powerful stellar wind in a young stellar cluster is argued to increase the maximal CR energies at a given evolution stage of supernova remnant (SNR) and can convert a sizeable fraction of the kinetic energy release into energetic particles.

Bykov, A. M.; Gladilin, P. E.; Osipov, S. M.

139

Interaction of Rayleigh-Taylor fingers and circumstellar cloudlets in young supernova remnants  

CERN Multimedia

We discover a new dynamical mechanism that significantly enhances the growth of Rayleigh-Taylor fingers developed near the contact interface between the supernova ejecta and swept-up ambient gas in young supernova remnants if the supernova remnant expands into a clumpy (cloudy) circumstellar medium. Our numerical simulation demonstrates that large Rayleigh-Taylor fingers can obtain a sufficient terminal velocity to protrude through the forward shock front by taking extra kinetic energy from vorticies generated by shock-cloud interactions. We suggest this mechanism as a means to generate the aspherical expansion of the supernova ejecta. Ambient magnetic fields are stretched and amplified as the Rayleigh-Taylor fingers protrude, possibly leading to strongly enhanced radio emission. The material in the protrusions originates from the ejected stellar material with greatly enhanced heavy elements. Therefore, it can be a strong X-ray emitter. The timescale for the Rayleigh-Taylor fingers to reach the forward shock ...

Jun, B I; Norman, M L; Jun, Byung Il; Norman, Michael L

1996-01-01

140

Hydrodynamic Simulation of Supernova Remnants Including Efficient Particle Acceleration  

CERN Multimedia

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 report on a technique that couples nonlinear diffusive shock acceleration, including the backreaction of the accelerated particles on the structure of the forward and reverse shocks, with a hydrodynamic simulation of SNR evolution. Compared to models which ignore CRs, the most important hydrodynamical effects of placing a significant fraction of shock energy into CRs are larger shock compression ratios and lower temp...

Ellison, D C; Ballet, J; Ellison, Donald C.; Decourchelle, Anne; Ballet, Jean

2004-01-01

 
 
 
 
141

A Survey of Supernova Remnants detected by Fermi-LAT  

Science.gov (United States)

The Fermi Gamma-ray Space Telescope has firmly identified GeV emission from more than a dozen supernova remnants (SNRs) in its first years of operation. Long thought to be capable of supplying the high energy cosmic rays in the Galaxy, SNR shocks are ideal sites to study cosmic-ray acceleration. Here we review the SNRs detected by Fermi-LAT, and discuss their properties. The population of detected remnants spans a large range of ages and environments, allowing for a comparative study of acceleration efficiency. The inclusion of gamma-ray data in multi-wavelength models improves our general understanding of these SNRs, constraining physical parameters including the magnetic field, gas density and energetics.

Hewitt, John W.; Fermi LAT Collaboration

2012-01-01

142

Thermal X-ray Spectra of Supernova Remnants  

CERN Multimedia

The fast shocks that characterize supernova remnants heat circumstellar and ejecta material to extremely high temperatures, resulting in significant X-ray emission. The X-ray spectrum from an SNR carries a wealth of information about the temperature and ionization state of the plasma, the density distribution of the postshock material, and the composition of the ejecta. This, in turn, places strong constraints on the properties of the progenitor star, the explosive nucleosynthesis that produced the remnant, the properties of the environment into which the SNR expands, and the effects of particle acceleration on its dynamical evolution. Here I present results from X-ray studies SNRs in various evolutionary states, and highlight key results inferred from the thermal emission.

Slane, Patrick

2013-01-01

143

ASYMMETRIES IN THE EXPANSION AND EMISSION FROM YOUNG SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

[en] We present two-dimensional and three-dimensional numerical simulations of asymmetric young supernova remnants (SNRs) carried out with the hydrodynamical code YGUAZU, aiming to quantitatively assess the role of different factors that may give origin to such asymmetries in their expansion. In particular, we are interested in modeling the morphology of Tycho's SNR to address whether the companion star of a Type Ia supernova progenitor has played a role in the subsequent evolution of the remnant. With the results from the numerical simulations, we can not only study the morphology of the SNR but also compute the emission of the remnant in different spectral bands. In particular, we simulate X-ray maps, which can be directly compared to recent and previous observations of Tycho's SNR. Our results suggest that the most likely explanation for Tycho's morphology is that after the supernova (SN) explosion the shock front stripped the envelope of its companion. We represent this effect by adding a conical region with an enhanced density into the initial sphere immediately after the explosion. Assuming that Tycho's companion was a massive red giant star, we explore different values of the angle of aperture and mass excess of the conical region. A good agreement with observational data was found for the model with a mass excess of 0.3 Msun and an aperture of 900. After the collision with the SN shock wave, the companion would become an He-rich star. This scenario would gain observational support if a star with these characteristics is found in the vicinity of the center of the SN explosion.

2011-01-20

144

DA 530: A Supernova Remnant in a Stellar Wind Bubble  

Science.gov (United States)

The high-latitude supernova remnant (SNR) DA 530 (G93.3+6.9), apparently a typical shell remnant, has highly polarized radio continuum emission and a very uniform circumferential magnetic field. We present new radio continuum (408 and 1420 MHz) and H I line observations, made with the Dominion Radio Astrophysical Observatory Synthesis Telescope, and we have made the first detection of X-ray emission from the SNR, using the ROSAT Position-Sensitive Proportional Counter. The SNR lies within a shell of H I, possibly created by an earlier stellar wind, whose kinematic distance is nominally 2.5 kpc but whose actual distance may be larger. The X-ray emission is extremely faint. A Raymond-Smith ionization-equilibrium model fits the data and suggests a very low density, ~0.05 cm-3, consistent with the occurrence of the supernova in a stellar wind cavity, but this model yields an explosion energy 100 times lower than the accepted value. A nonequilibrium shock model, incorporating a range of ionization timescales, is able to give more realistic physical parameters for the supernova remnant. On the balance of the evidence, we place DA 530 at a distance of 3.5 kpc, the largest distance permitted by the H I observations, where it lies 420 pc above the Galactic plane. The explosion, probably a Type Ia supernova, in a low-density cavity has resulted in weak X-ray emission and slow evolution. The explosion energy was 3.9x1050 ergs and the age is ~5000 years. The remnant, having swept up 3.9 Msolar in an ambient density of ~0.01 cm-3, is only now in the adiabatic phase, and this explains the absence of detected optical emission. Despite the low ambient density the efficiency of generation of synchrotron radio emission is ~0.4%, higher than in some historical SNRs. The ratio of radio to X-ray flux is about 100 times that for the remnant of SN 1006, which has comparable radio continuum properties. The very uniform magnetic field is not explained. DA 530 joins a small group of remnants at high Galactic latitude with unusual features, perhaps resulting from low ambient densities. Inhomogeneous nonequilibrium ionization models may be required for the interpretation of the X-ray emission from many other older SNRs.

Landecker, T. L.; Routledge, D.; Reynolds, S. P.; Smegal, R. J.; Borkowski, K. J.; Seward, F. D.

1999-12-01

145

Kinematics of Supernova Remnants: Status of X-Ray Observations  

CERN Document Server

A supernova (SN) explosion drives stellar debris into the circumstellar material (CSM) filling a region on a scale of parsecs with X-ray emitting plasma. The velocities involved in supernova remnants (SNRs), thousands of km/s, can be directly measured with medium and high-resolution X-ray spectrometers and add an important dimension to our understanding of the last stages of the progenitor, the explosion mechanism, and the physics of strong shocks. After touching on the ingredients of SNR kinematics, I present a summary of the still-growing measurement results from SNR X-ray observations. Given the advances in 2D/3D hydrodynamics, data analysis techniques, and especially X-ray instrumentation, it is clear that our view of SNRs will continue to deepen in the decades ahead.

Dewey, Daniel

2010-01-01

146

A new optical supernova remnant in Crux  

International Nuclear Information System (INIS)

Optical nebulosity has been found associated with the radio supernova remnant G296.1 - 0.7. It has a collisionally excited spectrum which indicates electron densities as high as 2 x 103 cm-3. Its distance is estimated at between 3 and 5 kpc from two independent considerations. The full width at half maximum of the internal velocity dispersion in the individual filaments is 42 km/s. This is the only new optical SNR discovered in a search at 70 radio SNR positions south of -180 on SRC Schmidt Survey plates. (author)

1977-01-01

147

VHE Gamma-ray Supernova Remnants  

Energy Technology Data Exchange (ETDEWEB)

Increasing observational evidence gathered especially in X-rays and {gamma}-rays during the course of the last few years support the notion that Supernova remnants (SNRs) are Galactic particle accelerators up to energies close to the ''knee'' in the energy spectrum of Cosmic rays. This review summarizes the current status of {gamma}-ray observations of SNRs. Shell-type as well as plerionic type SNRs are addressed and prospect for observations of these two source classes with the upcoming GLAST satellite in the energy regime above 100 MeV are given.

Funk, Stefan; /KIPAC, Menlo Park

2007-01-22

148

Spitzer Spectral Mapping of Supernova Remnant Cassiopeia A  

CERN Multimedia

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 [SiII], giving way to [SIV] and, at even further distances, high-energy X-rays from hydrogenic silicon. Two compact, crescent-shaped clumps with highly enhanced neon abundance are arranged symmetrically around the central neutron star. These neon crescents are very closely aligned with the "kick" direction of the compact object from the remnant's expansion center, tracing a new axis of explosion asymmetry. They indicate tha...

Smith, J D T; Delaney, Tracey; Rho, Jeonghee; Gomez, Haley; Kozasa, Takashi; Reach, William; Isensee, Karl

2008-01-01

149

SPITZER SPECTRAL MAPPING OF SUPERNOVA REMNANT CASSIOPEIA A  

International Nuclear Information System (INIS)

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 postshock bright ring. The global electron density increases by ?> 100 at the shock to ?104 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 II] giving way to [S IV] and, at even further distances, high-energy X-rays from hydrogenic silicon. Two compact, crescent-shaped clumps with highly enhanced neon abundance are arranged symmetrically around the central neutron star. These neon crescents are very closely aligned with the kick direction of the compact object from the remnant's expansion center, tracing a new axis of explosion asymmetry. They indicate that much of the apparent macroscopic elemental mixing may arise from different compositional layers of ejecta now passing through the reverse shock along different directions.

2009-03-01

150

RADIO POLARIMETRY SIGNATURES OF STRONG MAGNETIC TURBULENCE IN SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

[en] We discuss the emission and transport of polarized radio-band synchrotron radiation near the forward shocks of young shell-type supernova remnants, for which X-ray data indicate a strong amplification of turbulent magnetic field. Modeling the magnetic turbulence through the superposition of waves, we calculate the degree of polarization and the magnetic polarization direction which is at 90 deg. to the conventional electric polarization direction. We find that isotropic strong turbulence will produce weakly polarized radio emission even in the absence of internal Faraday rotation. If anisotropy is imposed on the magnetic-field structure, the degree of polarization can be significantly increased, provided internal Faraday rotation is inefficient. Both for shock compression and a mixture with a homogeneous field, the increase in polarization degree goes along with a fairly precise alignment of the magnetic-polarization angle with the direction of the dominant magnetic-field component, implying tangential magnetic polarization at the rims in the case of shock compression. We compare our model with high-resolution radio polarimetry data of Tycho's remnant. Using the absence of internal Faraday rotation we find a soft limit for the amplitude of magnetic turbulence, ?B ?0. An alternative viable scenario involves anisotropic turbulence with stronger amplitudes in the radial direction, as was observed in recent Magnetohydrodynamics simulations of shocks propagating through a medium with significant density fluctuations.

2009-05-10

151

A Survey of Hydroxyl Toward Supernova Remnants: Evidence for Extended 1720 MHz Maser Emission  

CERN Document Server

We present the results of GBT observations of all four ground-state hydroxyl (OH) transitions toward 16 supernova remnants which show OH(1720 MHz) maser emission. This species of maser is well established as an excellent tracer of an ongoing interaction between the remnant and dense molecular material. For ten remnants we detect a significantly higher flux density with a single dish than has been reported with interferometric observations. We infer that spatially extended, low level maser emission is a common phenomenon that traces the large-scale interaction in maser-emitting supernova remnants. Additionally we use a collisional pumping model to fit the physical conditions under which OH is excited behind the supernova shock front.

Hewitt, J W; Wardle, M

2008-01-01

152

The mass and structure of the remnant of Tycho's supernova  

International Nuclear Information System (INIS)

[en] A high resolution X-ray image of Tycho's supernova remnant obtained from the Einstein Observatory reveals three components of X-ray emission: shocked interstellar material, diffuse ejecta, and clumpy ejecta. This picture is applied to derive the mass of X-ray emitting material. Assuming a distance of 3 kpc, an absorbing column density of 3 x 1021 atoms/cm2, and using an ion-electron non-equilibrium calculation for the emissivity, the average density of the ISM is 0.4 atoms/cm3, and the energy contained in the remnant is 1.4 x 1051 ergs. The total mass of X-ray emitting material in the remnant is approx. 4 solar masses, approx. 2 solar masses ejecta and approx. 2 solar masses swept up, putting the remnant at an intermediate state between a free expansion and the Sedov phase. There is no evidence for neutron star. The upper limit on the surface temperature is in the range 1.1 to 1.8 x 106K. (Auth.)

1982-09-02

153

Eruption of supernova shock waves  

International Nuclear Information System (INIS)

[en] The initial burst of radiation from a supernova occurs as the shock wave which was generated by the explosion in the stellar core propagates into the photosphere. It is shown that the radiative hydrodynamics in the photospheric region should not be very sensitive to whether ordinary diffusion or flux-limited diffusion is used. Examination of the published numerical studies indicates that the radiation from the erupting supernova shock wave accelerates the matter in front of the shock so that the velocity discontinuity vanishes; a gas-viscous shock does not form, and there is no intense burst of hard X-rays above several keV. The published estimates of the softer X-ray emission from supernova shock waves are unaffected by the considerations presented here

1981-03-01

154

Azimuthal Density Variations Around the Rim of Tycho's Supernova Remnant  

CERN Document Server

{\\it Spitzer} images of Tycho's supernova remnant in the mid-infrared reveal limb-brightened emission from the entire periphery of the shell and faint filamentary structures in the interior. As with other young remnants, this emission is produced by dust grains, warmed to $\\sim 100$ K in the post-shock environment by collisions with energetic electrons and ions. The ratio of the 70 to 24 $\\mu$m fluxes is a diagnostic of the dust temperature, which in turn is a sensitive function of the plasma density. We find significant variations in the 70/24 flux ratio around the periphery of Tycho's forward shock, implying order-of-magnitude variations in density. While some of these are likely localized interactions with dense clumps of the interstellar medium, we find an overall gradient in the ambient density surrounding Tycho, with densities 3-10 times higher in the NE than in the SW. This large density gradient is qualitatively consistent with the variations in the proper motion of the shock observed in radio and X-r...

Williams, Brian J; Ghavamian, Parviz; Hewitt, John W; Mao, S Alwin; Petre, Robert; Reynolds, Stephen P; Blondin, John M

2013-01-01

155

Infrared [Fe II] and Dust Emissions from Supernova Remnants  

CERN Multimedia

Supernova remnants (SNRs) are strong thermal emitters of infrared radiation. The most prominent lines in the near-infrared spectra of SNRs are [Fe II] lines. The [Fe II] lines are from shocked dense atomic gases, so they trace SNRs in dense environments. After briefly reviewing the physics of the [Fe II] emission in SNR shocks, I describe the observational results which show that there are two groups of SNRs bright in [Fe II] emission: middle-aged SNRs interacting with molecular clouds and young core-collapse SNRs in dense circumstellar medium. The SNRs belonging to the former group are also bright in near-infrared H$_2$ emission, indicating that both atomic and molecular shocks are pervasive in these SNRs. The SNRs belonging to the latter group have relatively small radii in general, implying that most of them are likely the remnants of SN IIL/b or SN IIn that had strong mass loss before the explosion. I also comment on the "[Fe II]-H$_2$ reversal" in SNRs and on using the [Fe II]-line luminosity as an indic...

Koo, Bon-Chul

2013-01-01

156

Discovery of optical candidate supernova remnants in Sagittarius  

CERN Document Server

During an [O III] survey for planetary nebulae, we identified a region in Sagittarius containing several candidate Supernova Remnants and obtained deep optical narrow-band images and spectra to explore their nature. The images of the unstudied area have been obtained in the light of Halpha+[N II], [S II] and [O III]. The resulting mosaic covers an area of 1.4x1.0 deg^2 where filamentary and diffuse emission was discovered, suggesting the existence of more than one supernova remnants (SNRs) in the area. Deep long slit spectra were also taken of eight different regions. Both the flux calibrated images and the spectra show that the emission from the filamentary structures originates from shock-heated gas, while the photo-ionization mechanism is responsible for the diffuse emission. Part of the optical emission is found to be correlated with the radio at 4850 MHz suggesting their association, while the WISE infrared emission found in the area at 12 and 22 micron marginally correlates with the optical. The presenc...

Alikakos, J; Christopoulou, P E; Goudis, C D

2012-01-01

157

Exploration of Galactic ?-ray supernova remnants  

Science.gov (United States)

New generational very-high-energy telescope arrays have been detecting more than 120 TeV ?-ray sources. Multi-wavelength observations on these ?-ray sources have proven to be robust in shedding light on their nature. The coming radio telescope arrays like ASKAP and FAST may find more faint (extended) radio sources due to their better sensitivities and resolutions, might identify more previously un-identified ?-ray sources and set many new targets for future deep surveys by very-high-energy ground-based telescopes like LHAASO. We in the paper summarize a list of known Galactic ?-ray Supernova Remnants (SNRs) with or without radio emissions so far, which includes some SNRs deserving top priority for future multi-wave-length observations.

Tian, WenWu; Zhang, JianLi

2013-08-01

158

Neutral hydrogen towards Tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] The authors have observed the radio remnant of Tycho's Supernova (AD 1572), 3C10, with the Cambridge Half-Mile-Telescope (HMT). Two complete syntheses, overlapping in velocity coverage, were made in September 1979. In order to derive accurate HI absorption measurements towards the source, it is important to include carefully the contribution from large scale emission. Data containing this large-scale structure, physically unobtainable with the HMT, were derived from the work of Weaver and Williams (1973) and Williams (1973), and added to the synthesis maps. Continuum emission was subtracted from these 'composite' maps to give the final channel maps. A 'pie slice' representation of an RA-velocity plot through the centre of the field is given. Absorption, spin temperature and column density profiles for the HI along the line of sight to 3C10 were derived, and a value for the distance to 3C10 estimated. (Auth.)

1981-06-26

159

Modified equipartition calculation for supernova remnants  

CERN Multimedia

Determination of the magnetic field strength in the interstellar medium is one of the most complex tasks of contemporary astrophysics. We can only estimate the order of magnitude of the magnetic field strength by using a few very limited methods. Besides Zeeman effect and Faraday rotation, the equipartition or the minimum-energy calculation is a widespread method for estimating magnetic field strength and energy contained in the magnetic field and cosmic ray particles by using only the radio synchrotron emission. Despite of its approximate character, it remains a useful tool, especially when there is no other data about the magnetic field in a source. In this paper we give a modified calculation which we think is more appropriate for estimating magnetic field strengths and energetics in supernova remnants (SNRs). Finally, we present calculated estimates of the magnetic field strengths for all Galactic SNRs for which the necessary observational data are available. The web application for calculation of the mag...

Arbutina, B; Andjelic, M M; Pavlovic, M Z; Vukotic, B

2011-01-01

160

Generation of Cosmic rays in Historical Supernova Remnants  

Directory of Open Access Journals (Sweden)

Full Text Available We present the results of observations of two types of Galactic supernova remnants with the SHALON mirror Cherenkov telescope of Tien-Shan high-mountain Observatory: the shell-type supernova remnants Tycho, Cas A and IC 443; plerions Crab Nebula, 3c58(SN1181) and Geminga (probably plerion). The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (800 GeV - 100 TeV) gamma-rays in Tycho's supernova remnant. The data obtainedsuggest that the very high energy gamma-ray emission in the objects being discussedis different in origin.

Sinitsyna V.G.; Sinitsyna V.Y.

2013-01-01

 
 
 
 
161

Generation of Cosmic rays in Historical Supernova Remnants  

Science.gov (United States)

We present the results of observations of two types of Galactic supernova remnants with the SHALON mirror Cherenkov telescope of Tien-Shan high-mountain Observatory: the shell-type supernova remnants Tycho, Cas A and IC 443; plerions Crab Nebula, 3c58(SN1181) and Geminga (probably plerion). The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (800 GeV - 100 TeV) gamma-rays in Tycho's supernova remnant. The data obtainedsuggest that the very high energy gamma-ray emission in the objects being discussedis different in origin.

Sinitsyna, V. G.; Sinitsyna, V. Y.

2013-06-01

162

Generation of cosmic rays in historical supernova remnants  

International Nuclear Information System (INIS)

[en] We present the results of observations of two types of Galactic supernova remnants with the SHALON mirror Cherenkov telescope of Tien-Shan high-mountain Observatory: the shell-type supernova remnants Tycho, Cas A and IC 443; plerions Crab Nebula, 3c58(SN1181) and Geminga (probably plerion). The experimental data have confirmed the prediction of the theory about the hadronic generation mechanism of very high energy (800 GeV - 100 TeV) gamma-rays in Tycho's supernova remnant. The data obtained suggest that the very high energy gamma-ray emission in the objects being discussed is different in origin. (authors)

2013-03-18

163

X-ray surface brightness of Kepler's supernova remnant  

International Nuclear Information System (INIS)

We have observed Kepler's supernova remnant (SNR) with the imaging instruments on board the Einstein Observatory. The 0.15-4.5 keV flux incident on the Earth is 1.2 x 10-10 ergs cm-2 s-1; the flux corrected for interstellar absorption is 3.4 x 10-10 ergs cm-2 s-1 (L/sub x/ = 1.0 x 1036 ergs s-1 at D = 5 kpc) if the absorbing column density is N/sub H/ = 2.8 x 1021 cm-2. The remnant is circular and shows a strong shell which is at least 5 times brighter in the north than in the south. The X-ray observations do not unambiguously determine whether the remnant is in the adiabatic or the free expansion phase. If the remnant is in the adiabatic phase, the density of the interstellar medium (ISM) (2/sub e/>/sup 1/2/) surrounding Kepler's SNR must be about 5 cm-3. If the remnant is in the free expansion phase, where most of the emission arises from shock-heated ejecta, the ISM density must still be relatively high, n/sub i/> or approx. =0.1 cm-3. Even if the ISM is very inhomogeneous, with very many small, dense clouds, we show that the mean density of the ISM must be greater than approx.0.1 cm-3. In any case, the density of the x-ray emitting gas must be high (2/sub e/>/sup 1/2/ > or approx. =10 cm-3), and the temperature must be fairly low (T/sub e/7 K). The relatively high ISM density which is required is surprising in view of Kepler's distance above the galactic plane, approx.600 pc. Possibly the ISM around Kepler's SNR and around other type i SNRs is dominated by the mass lost from the presupernova star

1983-01-01

164

Simulating Supernovae Remnants in Gas Clouds  

CERN Document Server

The Hydra $N$-body hydrodynamics code has been modified to model, from the end of the Sedov phase, the effects of supernovae on the surrounding medium. The motivation is to investigate the feedback of energy into the interstellar/intergalactic medium. We compare our results for supernova remnants (SNRs) in a uniform medium to previous detailed work on the late evolution of SNRs. The code is found to reproduce the bulk characteristics of SNRs well. Results on the effects of a single central SNR on Plummer clouds are presented. The feedback of kinetic energy and the percentage mass loss can be parameterised in terms of the cloud mass and characteristic radius in a simple way. The kinetic energy fraction returned to the ISM from a SNR is $<3$ per cent. The removal of gas from the cold, dense phase and the addition of energy due to the lowering of the potential energy of a cloud is at least as significant, if not much more so, than the kinetic energy leaving a cloud.

Goodwin, S; Thomas, P; Goodwin, Simon; Pearce, Frazer; Thomas, Peter

2000-01-01

165

The Hot and Energetic Universe: The astrophysics of supernova remnants and the interstellar medium  

CERN Multimedia

The study of both supernova remnants and the hot and cold phases of the interstellar medium are essential for understanding the final stages of stellar evolution and their feedback on the evolution of galaxies through injection of energy and heavy elements. These studies are also crucial for understanding the physics of supernovae, their cosmological implication, and the origin of galactic cosmic rays. The unique capabilities of Athena+ will allow us to explore a new parameter space. Spatially-resolved high-resolution spectroscopy using Athena+ X-IFU of young remnants will allow to characterize individual parcels of ejected material in the line of sight in terms of kinematics, ionization and composition, providing access to the three dimensional geometry of the explosion. Athena+ will also allow studying shock physics and particle acceleration in supernova remnants, as well as their interaction with their environment. Athena+ X-IFU will also characterize the ionization mechanisms competing in forming the comp...

Decourchelle, A; Badenes, C; Ballet, J; Bamba, A; Bocchino, F; Kaastra, J; Kosenko, D; Lallement, R; Lee, J; Lemoine-Goumard, M; Miceli, M; Paerels, F; Petre, R; Pinto, C; Plucinsky, P; Renaud, M; Sasaki, M; Smith, R; Tatischeff, V; Tiengo, A; Valencic, L; Vink, J; Wang, D; Wilms, J

2013-01-01

166

Spallative Nucleosynthesis in Supernova Remnants; 1, Analytical Estimates  

CERN Document Server

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, focusing on the first stages of Galactic chemical evolution (i.e. when metallicity Z < 0.01 Z_odot) We show that dynamical aspects must be taken into account carefully, and present analytical calculations of the spallation reactions induced by the EPs accelerated at both the forward and the reverse shocks following the SN explosion. Our results show that the production of Be in the early Galaxy is still poorly under...

Parizot, E; Parizot, Etienne; Drury, Luke

1999-01-01

167

X-Ray Studies of Supernova Remnants: A Different View of Supernova Explosions  

CERN Multimedia

The unprecedented spatial and spectral resolutions of Chandra have revolutionized our view of the X-ray emission from supernova remnants. The excellent data sets accumulated on young, ejecta dominated objects like Cas A or Tycho present a unique opportunity to study at the same time the chemical and physical structure of the explosion debris and the characteristics of the circumstellar medium sculpted by the progenitor before the explosion. Supernova remnants can thus put strong constraints on fundamental aspects of both supernova explosion physics and stellar evolution scenarios for supernova progenitors. This view of the supernova phenomenon is completely independent of, and complementary to, the study of distant extragalactic supernovae at optical wavelengths. The calibration of these two techniques has recently become possible thanks to the detection and spectroscopic follow-up of supernova light echoes. In this paper, I will review the most relevant results on supernova remnants obtained during the first...

Badenes, Carles

2010-01-01

168

DUST IN A TYPE Ia SUPERNOVA PROGENITOR: SPITZER SPECTROSCOPY OF KEPLER'S SUPERNOVA REMNANT  

Energy Technology Data Exchange (ETDEWEB)

Characterization of the relatively poorly understood progenitor systems of Type Ia supernovae is of great importance in astrophysics, particularly given the important cosmological role that these supernovae play. Kepler's supernova remnant, the result of a Type Ia supernova, shows evidence for an interaction with a dense circumstellar medium (CSM), suggesting a single-degenerate progenitor system. We present 7.5-38 {mu}m infrared (IR) spectra of the remnant, obtained with the Spitzer Space Telescope, dominated by emission from warm dust. Broad spectral features at 10 and 18 {mu}m, consistent with various silicate particles, are seen throughout. These silicates were likely formed in the stellar outflow from the progenitor system during the asymptotic giant branch stage of evolution, and imply an oxygen-rich chemistry. In addition to silicate dust, a second component, possibly carbonaceous dust, is necessary to account for the short-wavelength Infrared Spectrograph and Infrared Array Camera data. This could imply a mixed chemistry in the atmosphere of the progenitor system. However, non-spherical metallic iron inclusions within silicate grains provide an alternative solution. Models of collisionally heated dust emission from fast shocks (>1000 km s{sup -1}) propagating into the CSM can reproduce the majority of the emission associated with non-radiative filaments, where dust temperatures are {approx}80-100 K, but fail to account for the highest temperatures detected, in excess of 150 K. We find that slower shocks (a few hundred km s{sup -1}) into moderate density material (n{sub 0} {approx} 50-250 cm{sup -3}) are the only viable source of heating for this hottest dust. We confirm the finding of an overall density gradient, with densities in the north being an order of magnitude greater than those in the south.

Williams, Brian J.; Borkowski, Kazimierz J.; Reynolds, Stephen P. [Physics Department, North Carolina State University, Raleigh, NC 27695-8202 (United States); Ghavamian, Parviz [Department of Physics, Astronomy, and Geosciences, Towson University, Towson, MD 21252 (United States); Blair, William P. [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Long, Knox S. [STScI, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Sankrit, Ravi, E-mail: brian.j.williams@nasa.gov [SOFIA/USRA, NASA Ames Research Center, M/S N211-3, Moffett Field, CA 94035 (United States)

2012-08-10

169

The acceleration of cosmic rays in supernova remnants  

International Nuclear Information System (INIS)

[en] A prerequisite of any model of cosmic-ray acceleration is that it should predict time variations in the terrestrial and near-Earth cosmic-ray intensity which are not inconsistent with observations. The supernova remnant (SNR) acceleration model has been used here to predict such variations for a variety of parameters. It is shown that the results are rather similar to those inferred from studies of the 10Be/9Be abundance ratio in marine sediment cores as well as from measurements of cosmogenic nuclides in extraterrestrial samples. The implication is that the SNR model is allowable. Turning the argument round, if the SNR model is accepted by virtue of other arguments, then the more sensitive sediment core results, which are presently becoming available, may well be close to giving useful evidence for cosmic-ray intensity variations associated with the time of crossing of SNR shocks by the Earth. (author)

1987-01-01

170

Tycho's Remnant Provides Shocking Evidence for Cosmic Rays  

Science.gov (United States)

Astronomers have found compelling evidence that a supernova shock wave has produced a large amount of cosmic rays, particles of mysterious origin that constantly bombard the Earth. This discovery, made with NASA's Chandra X-ray Observatory, supports theoretical arguments that shock waves from stellar explosions may be a primary source of cosmic rays. This finding is important for understanding the origin of cosmic rays, which are atomic nuclei that strike the Earth's atmosphere with very high energies. Scientists believe that some are produced by flares on the Sun, and others by similar events on other stars, or pulsars or black hole accretion disks. But, one of the prime suspects has been supernova shock waves. Now, a team of astronomers has used Chandra observations of Tycho's supernova remnant to strengthen the case for this explanation. "With only a single object involved we can't state with confidence that supernova shock waves are the primary source of cosmic rays," said John P. Hughes of Rutgers University in Piscataway, New Jersey, and coauthor of a report to be published in an upcoming issue of The Astrophysical Journal. "What we have done is present solid evidence that the shock wave in at least one supernova remnant has accelerated nuclei to cosmic ray energies." In the year 1572, the Danish astronomer Tycho Brahe observed and studied the sudden appearance of a bright "new star" in the constellation Cassiopeia. Now known as Tycho's supernova remnant, the event created a sensation in Tycho's time because it exploded the myth that stars never change. Four centuries later, the Chandra results on Tycho's remnant show that some modern ideas of the aftermath of supernova explosions may have to be revised. The report by Hughes and colleagues demonstrates that the shock wave produced by the explosive disruption of the star behaves in a way that cannot be explained by the standard theory. The supernova debris is observed to expand at a speed of about six million miles per hour. This rapid expansion has created two X-ray emitting shock waves - one moving outward into the interstellar gas, and another moving inward into the stellar debris. These shock waves, analogous to the sonic boom produced by supersonic motion of an airplanes, produce sudden, large changes in pressure, and temperature behind the wave. According to the standard theory, the outward-moving shock should be about two light-years ahead of the stellar debris (that's half the distance from our sun to the nearest star). What Chandra found instead is that the stellar debris has kept pace with the outer shock and is only about half a light-year behind. "The most likely explanation for this behavior is that a large fraction of the energy of the outward-moving shock wave is going into the acceleration of atomic nuclei to speeds approaching the speed of light," said Jessica Warren, also of Rutgers University, and the lead author of the report in the Astrophysical Journal. Previous observations with radio and X-ray telescopes had established that the shock wave in Tycho's remnant was accelerating electrons to high energies. However, since high-speed atomic nuclei produce very weak radio and X-ray emission also, it was not known whether the shock wave was accelerating nuclei as well. The Chandra observations provide the strongest evidence yet that nuclei are indeed accelerated, and that the energy contained in high-speed nuclei is about 100 times that in the electrons. Hughes also pointed out that the Chandra result for Tycho's remnant significantly changes astronomers' view of the evolution of supernova remnants. A large component of cosmic ray nuclei alters the dynamics of the shock wave, and may require changing the way that astronomers estimate the explosive energy of a supernova from the properties of its remnant. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations

2005-09-01

171

Supernova remnant evolution in uniform and non-uniform media  

Science.gov (United States)

Aims:In this work numerical simulations showing the time evolution of supernova remnants (SNRs) in uniform and non-uniform interstellar medium (ISM) are presented. Methods: We use a hydrodynamic model including a kinematic calculation of the interstellar magnetic field. Important parameters influencing SNR evolution include the ejecta mass and energy of the remnant, as well as the ISM density and adiabatic index. Results: By varying these parameters we constructed an analytical expression giving the return time of the SNR reverse shock to the origin, in terms of these parameters. We also found that the reverse shock spends half of its time moving outward and the other half returning to the origin. Also computed is SNR evolution in non-uniform media where the blast wave moves from one medium into either a less or more dense medium. As the SNR moves into a medium of higher density a reflection wave is created at the interface between the two media which is driven back toward the center. This drives mass via a nonspherical flow away from the discontinuity. As this wave moves inward it also drags some of the ISM field lines (if the field is parallel with the interface) with it and heats the inside of the SNR resulting in larger temperatures in this region. When a SNR explodes in a medium with a high density and the blast wave propagates into a medium with a lower density, a cavity is being blown away changing the geometry of the high density region. Also, once the forward shock moves into the medium of less density a second reverse shock will start to evolve in this region.

Ferreira, S. E. S.; de Jager, O. C.

2008-01-01

172

Understanding particle acceleration at supernova shocks  

Science.gov (United States)

One century after the pioneering discovery of cosmic rays by V. Hess, the present generation of X- and gamma-ray telescopes is finally unravelling the origin of such an extraterrestrial radiation, at least for what concerns particles with energies below ˜10^8 GeV, which are thought to be accelerated at the forward shocks of Galactic supernova remnants (SNRs). I discuss the present theoretical understanding of efficient particle acceleration at non-relativistic, collisionless shocks, addressing with both analytical and numerical (particle-in-cell) techniques the crucial interplay between accelerated ions and magnetic turbulence. In SNRs, in fact, magnetic fields turn out to be a factor of 10-100 larger than in the interstellar medium, because of plasma instabilities triggered by energetic particles. In particular, I show 2D and 3D hybrid (fluid electrons - kinetic ions) simulations of non-relativistic collisionless shocks, pointing out the efficiency of Fermi acceleration and the role of the cosmic-ray-induced filamentation instability in amplifying the magnetic field up to the levels inferred at the blast waves of young Galactic remnants. Finally, I outline the observational counterparts of such a theory of particle acceleration at strong shocks in terms of SNR multi-wavelength emission, with a special attention to Tycho's SNR, arguably the best laboratory where to test hadron acceleration.

Caprioli, Damiano

2013-04-01

173

Three New Supernova Remnant OH Masers Near the Galactic Center Evidence for Large Scale Maser Emission from Supernova Remnants  

CERN Multimedia

A survey of the inner 8$^\\circ \\times 1^\\circ$ of the Galactic plane toward the Galactic center has been carried out at the 1720 MHz transition of OH molecule using the VLA in its D configuration with a resolution of with three supernova remnants G357.7+0.3, G1.13--0.1 (Sgr D) and G1.4--0.1 as well as new extended maser line emission from G357.7+0.3 and G357.7--0.1 (the Tornado Nebula) were then followed up by A-array observations with spectral and spatial resolutions of 0.3 \\kms and $\\approx3''\\times2''$, respectively. The 1720 MHz OH maser line emission is considered to be a powerful shock diagnostic and is collisionally pumped by H$_2$ molecules at the site where C-type supernova shocks drive into adjacent molecular clouds. The new observations show clear evidence of extended features coincident with compact and bright masers, the best example of which is a coherent feature over a scale of about 20 pc surrounding the shell of the SNR G357.7+0.3. We argue that this remarkable feature is an OH maser and is p...

Yusef-Zadeh, F; Roberts, D A; Robinson, B; Frail, D A

1999-01-01

174

Energy of Tycho's Supernova Remnant is increasing with time  

Digital Repository Infrastructure Vision for European Research (DRIVER)

It is shown, using the Zeldovich integral relations, that the energy of Tycho's Supernova Remnant is strongly growing with time, approximately as t1/3. This growth can be attributed to the exothermic reactions going inside the remnant. The use of the assumption of the adiabaticity of the motion insi...

Barenblatt, Grigory Isaakovich

175

Long slit echelle spectroscopy of supernova remnants IN M33  

International Nuclear Information System (INIS)

The authors have obtained long slit echelle spectroscopy for 10 of the brightest supernova remnants in M33 using the KPNO 4 m telescope. The profiles at II? indicate bulk motions in the range 100--350 km s-1 in these remnants. Nearly all of the objects show signs of contamination by low velocity II II emission at some level. This affects the line intensities measured from low resolution data and may affect diameter measurements of these remnants.

1988-01-01

176

Particle acceleration in supernova remnants, the Bell-Lucek hypothesis and the cosmic ray "knee"  

CERN Document Server

Young supernova remnants are thought to be the sites where cosmic ray acceleration occurs by the mechanism of diffusive shock acceleration. The maximum energy gained in this process is conventionally extimated to have a value close to, but distinctly below, the ``knee'' ($\\sim 10^{15}$ eV) of the cosmic-ray spectrum. Bell & Lucek (2001) have suggested that the generated cosmic rays simultaneously amplify the magnetic field around the supernova remnant shock to many times its pre-shock value. In this case the acceleration rate may be significantly increased and protons can easily reach energies up to $10^{17}$ eV. We use a ``simplified'' box model incorporating the magnetic field amplification suggested by Bell & Lucek to investigate the resulting modifications of the cosmic-ray spectrum. The model predicts a spectral break at high energies, close to the ``knee'' region, and in good accordance with observations.

O'Connor-Drury, L; Carroll, O

2003-01-01

177

Measuring the cosmic-ray acceleration efficiency of a supernova remnant.  

UK PubMed Central (United Kingdom)

Cosmic rays are the most energetic particles arriving at Earth. Although most of them are thought to be accelerated by supernova remnants, the details of the acceleration process and its efficiency are not well determined. Here we show that the pressure induced by cosmic rays exceeds the thermal pressure behind the northeast shock of the supernova remnant RCW 86, where the x-ray emission is dominated by synchrotron radiation from ultrarelativistic electrons. We determined the cosmic-ray content from the thermal Doppler broadening measured with optical spectroscopy, combined with a proper-motion study in x-rays. The measured postshock proton temperature, in combination with the shock velocity, does not agree with standard shock heating, implying that >50% of the postshock pressure is produced by cosmic rays.

Helder EA; Vink J; Bassa CG; Bamba A; Bleeker JA; Funk S; Ghavamian P; van der Heyden KJ; Verbunt F; Yamazaki R

2009-08-01

178

Suzaku Observations of Tycho's Supernova Remnant  

CERN Multimedia

Tycho's supernova remnant was observed by the XIS and HXD instruments onboard the Suzaku satellite on 2006 June 26-29 for 92 ks. The spectrum up to 30 keV was well fitted with a two-component model, consisting of a power-law with photon index of 2.7 and a thermal bremsstrahlung model with temperature of 4.7 keV. The former component can alternatively be modeled as synchrotron emission from a population of relativistic electrons with an estimated roll-off energy of around 1 keV. In the XIS spectra, in addition to the prominent Fe K_alpha line (6.445 keV), we observe for the first time significant K_alpha line emission from the trace species Cr and Mn at energies of 5.48 keV and 5.95 keV, respectively. Faint K_beta lines from Ca (4.56 keV) and Fe (7.11 keV) are also seen. The ionization states of Cr and Mn, based on their line centroids, are estimated to be similar to that of Fe K_alpha (Fe XV or XVI).

Tamagawa, T; Nakamura, S; Terada, Y; Bamba, A; Hiraga, J S; Hughes, J P; Hwang, U; Kataoka, J; Kinugasa, K; Kunieda, H; Tanaka, T; Tsunemi, H; Ueno, M; Holt, S S; Kokubun, M; Miyata, E; Szymkowiak, A; Takahashi, T; Tamura, K; Ueno, D; Makishima, K

2008-01-01

179

The spectrum of tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] The optical spectrum of filaments in Tycho's supernova remnant shows only H? and H? emission over the wavelength range 4700-8000 A. We suggest that the optical filaments producing this emission may be density enhancements at a temperature near 105 K. Even though we consider non-equilibrium processes which can lead to much lower electron temperatures than equilibrium models, it does not seem possible to reconcile the 21 cm absorption data, the optical proper motions, and the optical surface brightness. (orig.)[de] Das optische Spektrum der Filiamente des Supernovaueberrestes Tycho zeigt im Wellenlaengenbereich zwischen 4700-8000 A nur H? und H?-Emission. Es wird vorgeschlagen, die optischen Filiamente, die fuer diese Emission verantwortlich sind, als Dichtezunahmen bei einer Temperatur nahe 105 K zu interpretieren. Obwohl Nichtgleichgewichtsprozesse betrachtet werden, die zu weitaus geringeren Elektronentemperaturen fuehren als Gleichgewichtsmodelle, scheint es unmoeglich zu sein, die 21 cm-Absorptionsdaten, die optischen Eigenbewegungen und die optische Oberflaechenhelligkeit miteinander in Einklag zu bringen. (orig.)

1978-01-01

180

IRAS observations of supernova remnants - a comparison between their infrared and X-ray cooling rates  

Energy Technology Data Exchange (ETDEWEB)

A comparison is presented between the total IR and X-ray cooling rates of nine selected Galactic supernova remnants. The observed IR-to-X-ray cooling ratio (IRX ratio) values are larger than unity for most remnants, ranging from five for the adiabatic remnant Puppis A, to about 1000 for RCW 86. Most of the observed IR emission from the remnants can be attributed to thermal emission from dust collisionally heated by the shocked plasma. A comparison between the theoretical and observed IRX ratio shows that only two of the nine remnants have IRX ratios within a factor of about three of the expected value. Puppis A, Kepler, Tycho, and SN 1006 have IRX ratios that are significantly smaller than the theoretically predicted value, suggesting that the dust is significantly depleted in the ambient medium into which they are expanding. 41 references.

Dwek, E.; Petre, R.; Szymkowiak, A.; Rice, W.L.

1987-09-01

 
 
 
 
181

On the hadronic ?-ray emission from Tycho's supernova remnant  

Science.gov (United States)

Hadronic ?-ray emission from supernova remnants (SNRs) is an important tool to test shock acceleration of cosmic-ray protons. Tycho is one of nearly a dozen Galactic SNRs which are suggested to emit hadronic ?-ray emission. Among them, however, it is the only one in which the hadronic emission is proposed to arise from the interaction with a low-density (˜0.3 cm-3) ambient medium. Here we present an alternative hadronic explanation with a modest energy conversion efficiency (of the order of 1 per cent) for this young remnant. With such an efficiency, a normal electron-to-proton ratio (of the order of 10-2) is derived from the radio and X-ray synchrotron spectra, and an average ambient density that is at least one order of magnitude higher is derived from the hadronic ?-ray flux. This result is consistent with the multiband evidence of the presence of a dense medium from the north to the east of the Tycho SNR. The SNR-cloud association, in combination with the H i absorption data, helps to constrain the so-far controversial distance to Tycho and leads to an estimate of 2.5 kpc.

Zhang, Xiao; Chen, Yang; Li, Hui; Zhou, Xin

2013-02-01

182

Neutral Hydrogen in the Direction of the VELA Supernova Remnant  

Science.gov (United States)

We have carried out a study of the distribution and kinematics of the neutral hydrogen in the direction of the Vela supernova remnant (SNR). A field of 6.8d x 5.4d centered at l = 264.1d, b = -1.6d was surveyed using the Parkes 64 m radio telescope (half-power beamwidth 14.7? at 21 cm). Nearly 2300 H i profiles were obtained with a grid spacing of 7.5?. The presence of a thin, almost circular H i shell, centered at v = 1.6 +/- 0.8 km s^-1, is revealed. This shell delineates the outer border of the X-ray emission as shown in the ROSAT observations of Aschenbach, Egger, & Trümper and wraps around the receding part of the remnant. In addition, two higher velocity features possibly associated with Vela are observed at about -30 and 30 km s^-1. These features are interpreted as gas accelerated by the expansion of the supernova shock. The low systemic velocity observed suggests a distance shorter than 500 pc for the Vela SNR. The H i shell is ~7 deg in diameter and expands at v ~ 30 km s^-1. By assuming a distance of 350 pc, we calculate for this shell a linear radius of 22 pc, a swept-up mass of ~1200-2300 M_?, and an atomic preshock density of ~1-2 cm^-3. The kinetic energy transferred by the supernova shock into the interstellar medium is ~(1-2) x 10^49 ergs, while the initial energy of the explosion is estimated to be ~(1-2.5) x 10^51 ergs. We present the distribution of the column density of the neutral material absorbing the X-radiation, an essential parameter in the analysis of X-ray data. A comparison between the H i and H? emission suggests that the H i shell contains embedded dust that might be responsible for increased optical absorption in this region. On the other hand, the brightest arc-shaped optical filaments associated with the western side of Vela show good correspondence with the H i features. From a comparison between the H i and Molonglo Observatory Synthesis Telescope 843 MHz radio continuum emission, we find that the outermost arched radio filaments correlate well with the main ridge of the H i shell. No strong inhomogeneities were found in the ambient H i medium in the direction of Vela X (the central nebula, powered by the pulsar PSR B0833-45).

Dubner, G. M.; Green, A. J.; Goss, W. M.; Bock, D. C.-J.; Giacani, E.

1998-08-01

183

PHYSICAL STRUCTURE AND NATURE OF SUPERNOVA REMNANTS IN M101  

International Nuclear Information System (INIS)

Supernova remnant (SNR) candidates in the giant spiral galaxy M101 have been previously identified from ground-based H? and [S II] images. We have used archival Hubble Space Telescope (HST) H? and broadband images as well as stellar photometry of 55 SNR candidates to examine their physical structure, interstellar environment, and underlying stellar population. We have also obtained high-dispersion echelle spectra to search for shocked high-velocity gas in 18 SNR candidates, and identified X-ray counterparts to SNR candidates using data from archival observations made by the Chandra X-Ray Observatory. Twenty-one of these 55 SNR candidates studied have X-ray counterparts, although one of them is a known ultraluminous X-ray source. The multi-wavelength information has been used to assess the nature of each SNR candidate. We find that within this limited sample, ?16% are likely remnants of Type Ia SNe and ?45% are remnants of core-collapse SNe. In addition, about ?36% are large candidates which we suggest are either superbubbles or OB/H II complexes. Existing radio observations are not sensitive enough to detect the non-thermal emission from these SNR candidates. Several radio sources are coincident with X-ray sources, but they are associated with either giant H II regions in M101 or background galaxies. The archival HST H? images do not cover the entire galaxy and thus prevents a complete study of M101. Furthermore, the lack of HST [S II] images precludes searches for small SNR candidates which could not be identified by ground-based observations. Such high-resolution images are needed in order to obtain a complete census of SNRs in M101 for a comprehensive investigation of the distribution, population, and rates of SNe in this galaxy.

2012-01-01

184

TeV Gamma-Rays from Old Supernova Remnants  

CERN Multimedia

We study the emission from an old supernova remnant (SNR) with an age of around 10^5 yrs and that from a giant molecular cloud (GMC) encountered by the SNR. When the SNR age is around 10^5 yrs, hadron acceleration is efficient enough to emit TeV gamma-rays both at the shock of the SNR and that in the GMC. The maximum energy of primarily accelerated electrons is so small that TeV gamma-rays and X-rays are dominated by hadronic processes, pi^0-decay and synchrotron radiation from secondary electrons, respectively. However, if the SNR is older than several 10^5 yrs, there are few high-energy particles emitting TeV gamma-rays because of the energy loss effect and/or the wave damping effect occurring at low-velocity isothermal shocks. It is found that the ratio of TeV gamma-ray (1-10 TeV) to X-ray (2-10 keV) energy flux can be more than ~10^2. Such a source showing large flux ratio may be a possible origin of recently discovered unidentified TeV sources.

Yamazaki, R; Bamba, A; Yoshida, T; Tsuribe, T; Takahara, F; Yamazaki, Ryo; Kohri, Kazunori; Bamba, Aya; Yoshida, Tatsuo; Tsuribe, Toru; Takahara, Fumio

2006-01-01

185

X-Ray Emission from Strongly Asymmetric Circumstellar Material in the Remnant of Kepler's Supernova  

Science.gov (United States)

Kepler's supernova remnant resulted from a thermonuclear explosion, but is interacting with circumstellar material (CSM) lost from the progenitor system. We describe a statistical technique for isolating X-ray emission due to CSM from that due to shocked ejecta. Shocked CSM coincides well in position with 24 ?m emission seen by Spitzer. We find most CSM to be distributed along the bright north rim, but substantial concentrations are also found projected against the center of the remnant, roughly along a diameter with position angle ~100°. We interpret this as evidence for a disk distribution of CSM before the supernova, with the line of sight to the observer roughly in the disk plane. We present two-dimensional hydrodynamic simulations of this scenario in qualitative agreement with the observed CSM morphology. Our observations require Kepler to have originated in a close binary system with an asymptotic giant branch star companion.

Burkey, Mary T.; Reynolds, Stephen P.; Borkowski, Kazimierz J.; Blondin, John M.

2013-02-01

186

Supernova Remnants as the Sources of Galactic Cosmic Rays  

CERN Multimedia

The origin of cosmic rays holds still many mysteries hundred years after they were first discovered. Supernova remnants have for long been the most likely sources of Galactic cosmic rays. I discuss here some recent evidence that suggests that supernova remnants can indeed efficiently accelerate cosmic rays. For this conference devoted to the Astronomical Institute Utrecht I put the emphasis on work that was done in my group, but placed in a broader context: efficient cosmic-ray acceleration and the im- plications for cosmic-ray escape, synchrotron radiation and the evidence for magnetic- field amplification, potential X-ray synchrotron emission from cosmic-ray precursors, and I conclude with the implications of cosmic-ray escape for a Type Ia remnant like Tycho and a core-collapse remnant like Cas A.

Vink, Jacco

2012-01-01

187

Supernova Remnants as the Sources of Galactic Cosmic Rays  

Science.gov (United States)

The origin of cosmic rays holds still many mysteries hundred years after they were first discovered. Supernova remnants have for long been the most likely sources of Galactic cosmic rays. I discuss here some recent evidence that suggests that supernova remnants can indeed efficiently accelerate cosmic rays. For this conference devoted to the Astronomical Institute Utrecht I put the emphasis on work that was done in my group, but placed in a broader context: efficient cosmic-ray acceleration and the implications for cosmic-ray escape, synchrotron radiation and the evidence for magnetic-field amplification, potential X-ray synchrotron emission from cosmic-ray precursors, and I conclude with the implications of cosmic-ray escape for a Type Ia remnant like Tycho and a core-collapse remnant like Cas A.

Vink, J.

2013-01-01

188

Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant  

CERN Document Server

We present far-ultraviolet observations of the Antlia supernova remnant obtained with Far-ultraviolet IMaging Spectrograph (FIMS, also called SPEAR). The strongest lines observed are C IV 1548,1551 and C III 977. The C IV emission of this mixed-morphology supernova remnant shows a clumpy distribution, and the line intensity is nearly constant with radius. The C III 977 line, though too weak to be mapped over the whole remnant, is shown to vary radially. The line intensity peaks at about half the radius, and drops at the edge of the remnant. Both the clumpy distribution of C IV and the rise in the C IV to C III ratio towards the edge suggest that central emission is from evaporating cloudlets rather than thermal conduction in a more uniform, dense medium.

Shinn, Jong-Ho; Sankrit, Ravi; Ryu, Kwang-Sun; Kim, Il-Joong; Han, Wonyong; Nam, Uk-Won; Park, Jang-Hyun; Edelstein, Jerry; Korpela, Eric J

2007-01-01

189

Cygnus Superbubble as the remnant of a peculiar supernova  

Energy Technology Data Exchange (ETDEWEB)

An analytic solution is obtained for the evolution of a supernova remnant during the radiative-cooling phase. The Cygnus Superbubble x-ray source could have been formed by the explosion of a single supernova releasing an energy of 10/sup 52/--10/sup 53/ erg. Analysis of the light curve of the NGC 1058 supernova 1961v demonstrates that it represents a roughly-equal2 x 10/sup 52/ erg outburst of a supermassive (roughly-equal10/sup 3/ M/sub sun/) star. Giant shell sources may form an evolutionary sequence, exemplified by R136a as the presupernova, supernova 1961v, and the Superbubble as the remnant.

Blinnikov, S.I.; Imshennik, V.S.; Utrobin, V.P.

1982-11-01

190

Radio polarization and magnetic fields in six supernova remnants  

International Nuclear Information System (INIS)

8.4 GHz linear polarization maps, obtained with the Parkes radio telescope, are presented for six southern supernova remnants. These results are compared with published and unpublished polarization maps at 5 GHz to derive the magnetic field direction and Faraday rotation measure distribution. These results are part of a program to map the magnetic fields in galactic supernova remnants and complement our program to obtain high-resolution maps of galactic SNRs using the Molonglo Observatory Synthesis Telescope; five new Molonglo maps are presented here. 26 refs., figs.

1989-01-01

191

Onion-shell model for cosmic ray electrons and radio synchrotron emission in supernova remnants  

International Nuclear Information System (INIS)

The spectrum of cosmic ray electrons, accelerated in the shock front of a supernova remnant (SNR), is calculated in the test-particle approximation using an onion-shell model. Particle diffusion within the evolving remnant is explicity taken into account. The particle spectrum becomes steeper with increasing radius as well as SNR age. Simple models of the magnetic field distribution allow a prediction of the intensity and spectrum of radio synchrotron emission and their radial variation. The agreement with existing observations is satisfactory in several SNR's but fails in other cases. Radiative cooling may be an important effect, especially in SNR's exploding in a dense interstellar medium

1985-01-01

192

Self-consistent models for the X-ray emission from supernova remnants  

International Nuclear Information System (INIS)

A novel solution to the problem of time dependent ionization in shock heated plasmas has been developed and incorporated into a standard, spherically symmetric hydrodynamic shock code. The approach to the ionization calculation is to use the eigenvalue method of solution for the matrix formed from the coupled system of rate equations expressing the time development of the ionization structure. An important tool for studying the evolution of supernova remnants has been developed. As a first application all of the available observations of the remnant of Kepler's supernova (SN 1604) obtained with the imaging and spectral instruments of the Einstein Observatory have been fitted. Two classes of models adequately describe the data: (1) a Sedov model, requiring near solar abundances, and (2) a reverse-shock model, which requires significant heavy element overabundances. The implications of this result are discussed. The distributions of luminosity, spectrum, and diameter were examined for an X-ray selected sample of supernovae remnants in the Large Magellanic Cloud.

1984-01-01

193

X-ray studies of supernova remnants: a different view of supernova explosions.  

Science.gov (United States)

The unprecedented spatial and spectral resolutions of Chandra have revolutionized our view of the X-ray emission from supernova remnants. The excellent datasets accumulated on young, ejecta-dominated objects like Cas A or Tycho present a unique opportunity to study at the same time the chemical and physical structure of the explosion debris and the characteristics of the circumstellar medium sculpted by the progenitor before the explosion. Supernova remnants can thus put strong constraints on fundamental aspects of both supernova explosion physics and stellar evolution scenarios for supernova progenitors. This view of the supernova phenomenon is completely independent of, and complementary to, the study of distant extragalactic supernovae at optical wavelengths. The calibration of these two techniques has recently become possible thanks to the detection and spectroscopic follow-up of supernova light echoes. In this paper, I review the most relevant results on supernova remnants obtained during the first decade of Chandra and the impact that these results have had on open issues in supernova research. PMID:20404206

Badenes, Carles

2010-04-19

194

X-ray studies of supernova remnants: a different view of supernova explosions.  

UK PubMed Central (United Kingdom)

The unprecedented spatial and spectral resolutions of Chandra have revolutionized our view of the X-ray emission from supernova remnants. The excellent datasets accumulated on young, ejecta-dominated objects like Cas A or Tycho present a unique opportunity to study at the same time the chemical and physical structure of the explosion debris and the characteristics of the circumstellar medium sculpted by the progenitor before the explosion. Supernova remnants can thus put strong constraints on fundamental aspects of both supernova explosion physics and stellar evolution scenarios for supernova progenitors. This view of the supernova phenomenon is completely independent of, and complementary to, the study of distant extragalactic supernovae at optical wavelengths. The calibration of these two techniques has recently become possible thanks to the detection and spectroscopic follow-up of supernova light echoes. In this paper, I review the most relevant results on supernova remnants obtained during the first decade of Chandra and the impact that these results have had on open issues in supernova research.

Badenes C

2010-04-01

195

Morphology of synchrotron emission in young supernova remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the framework of test-particle and cosmic-ray modified hydrodynamics, we calculate synchrotron emission radial profiles in young ejecta-dominated supernova remnants (SNRs) evolving in an ambient medium which is uniform in density and magnetic field. We find that, even without any magnetic field a...

Cassam-Chenai, Gamil; Decourchelle, Anne; Ballet, Jean; C. Ellison, Donald

196

Multiwavelength comparison of Cassiopeia A and Tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] A comparison of high resolution radio, optical, and X-ray images of two young supernova remnants (SNR), Cas A and Tycho, shows significant differences between them, Cas A probably broke into many small knots at the time of the initial explosion, whereas Tycho's SNR appears to be a more uniformly expanding blast wave

1982-06-01

197

An integral view of fast shocks around supernova 1006.  

Science.gov (United States)

Supernova remnants are among the most spectacular examples of astrophysical pistons in our cosmic neighborhood. The gas expelled by the supernova explosion is launched with velocities ~1000 kilometers per second into the ambient, tenuous interstellar medium, producing shocks that excite hydrogen lines. We have used an optical integral-field spectrograph to obtain high-resolution spatial-spectral maps that allow us to study in detail the shocks in the northwestern rim of supernova 1006. The two-component H? line is detected at 133 sky locations. Variations in the broad line widths and the broad-to-narrow line intensity ratios across tens of atomic mean free paths suggest the presence of suprathermal protons, the potential seed particles for generating high-energy cosmic rays. PMID:23413189

Nikoli?, Sladjana; van de Ven, Glenn; Heng, Kevin; Kupko, Daniel; Husemann, Bernd; Raymond, John C; Hughes, John P; Falcón-Barroso, Jesús

2013-02-14

198

New evidence for strong nonthermal effects in Tycho's supernova remnant  

CERN Document Server

We present for the case of Tycho's supernova remnant (SNR) the relation between the blast wave and contact discontinuity sizes calculated within the nonlinear kinetic theory of cosmic ray (CR) acceleration in SNRs. It is demonstrated that they are very well confirmed by recently published Chandra measurements, which show that the observed contact discontinuity radius is so close to the shock radius, that it can only be explained by the efficient CR acceleration which in turn makes the medium more compressible. Together with the recently determined new value E_{sn}=1.2x10^{51} erg of the SN explosion energy this gives an additional important confirmation that the predicted gamma-ray flux at TeV-energies (2-5)x10^{-13} erg/(cm^2 s), produced by accelerated nuclear CRs, is indeed expected from Tycho's SNR. Chandra measurements and the HEGRA upper limit of the TeV gamma-ray flux together limit the source distance d to 3.3 < d < 4 kpc.

Völk, H J; Ksenofontov, L T

2005-01-01

199

Observations of the remnants of three historical supernovae  

International Nuclear Information System (INIS)

[en] Radio maps are presented of the supernova remnants G11.2-0.3, G348.5+0.1 and G348.7+0.3, all three of which have been suggested as candidates for the remnants of supernovae in the 4th century AD. An HRI X-ray image of G11.2-0.3 is also shown. G11.2-0.3 is a bright, symmetric shell remnant which looks very like Tycho's or Kepler's SNRs. Its parameters are consistent with an (undetected) supernovae explosion 300-500 yr ago, but an alternative interpretation, that it is the remnant of the explosion of a massive star in AD 386, cannot be excluded. G348.5+0.1 and G348.7+0.3 have weaker, more ragged shells than does G11.2-0.3 and are probably much older. This would be consistent with one of these two remnants being the relic of the AD 393 explosion. (author)

1984-10-15

200

Observations of the remnants of three historical supernovae  

Energy Technology Data Exchange (ETDEWEB)

Radio maps are presented of the supernova remnants G11.2-0.3, G348.5+0.1 and G348.7+0.3, all three of which have been suggested as candidates for the remnants of supernovae in the 4th century AD. An HRI X-ray image of G11.2-0.3 is also shown. G11.2-0.3 is a bright, symmetric shell remnant which looks very like Tycho's or Kepler's SNRs. Its parameters are consistent with an (undetected) supernovae explosion 300-500 yr ago, but an alternative interpretation, that it is the remnant of the explosion of a massive star in AD 386, cannot be excluded. G348.5+0.1 and G348.7+0.3 have weaker, more ragged shells than does G11.2-0.3 and are probably much older. This would be consistent with one of these two remnants being the relic of the AD 393 explosion.

Downes, A. (Mullard Radio Astronomy Observatory, Cambridge (UK). Cavendish Lab.)

1984-10-15

 
 
 
 
201

X-ray spectra of supernova remnants  

International Nuclear Information System (INIS)

[en] High quality X-ray spectra for the brightest remnants are now available from several satellites. The data for Tycho's remnant, Cas A, and Kepler's remnant have been used to derive elemental abundances which appear mostly larger than average interstellar values and increase with respect to those values as one progresses from Mg to Ca. Iron appears low. All the abundances appear particularly high in Tycho. Spectral observations above 20 keV for Cas A and Tycho show that electron-ion equilibration proceeds faster than the Coulomb rate. Ionization-recombination equilibration, however, is almost certainly not attained in these young remnants, and this may account for the two temperature components found to fit the spectra best by most X-ray observers. Spectral evidence, coupled with optical evidence that Tycho's remnant is in the Sedov phase of evolution, indicate that the ejecta were not primarily iron. The older remnant in Puppis has been well studied by a crystal spectrometer and shows many informative line features. (Auth.)

1980-01-30

202

A Possible Site of Cosmic Ray Acceleration in the Supernova Remnant IC 443  

CERN Document Server

We present evidence for shock acceleration of cosmic rays to high energies (about 10 TeV) in the supernova remnant IC 443. X-ray imaging spectroscopy with ASCA reveals two regions of particularly hard emission: an unresolved source embedded in an extended emission region, and a ridge of emission coincident with the southeastern rim. Both features are located on part of the radio shell where the shock wave is interacting with molecular gas, and together they account for a majority of the emission at 7 keV. Though we would not have noticed it a priori, the unresolved feature is coincident with one resolved by the ROSAT HRI. Because this feature overlaps a unique region of flat radio spectral index (alpha 5,000 km/s). We conclude that the anomalous feature is most likely tracing enhanced particle acceleration by shocks that are formed as the supernova blast wave impacts the ring of molecular clouds.

Keohane, J W; Gotthelf, E V; Ozaki, M; Koyama, K; Keohane, Jonathan W.

1997-01-01

203

No cold dust within the supernova remnant Cassiopeia A.  

UK PubMed Central (United Kingdom)

A large amount (about three solar masses) of cold (18 K) dust in the prototypical type II supernova remnant Cassiopeia A was recently reported. It was concluded that dust production in type II supernovae can explain how the large quantities (approximately 10(8) solar masses) of dust observed in the most distant quasars could have been produced within only 700 million years after the Big Bang. Foreground clouds of interstellar material, however, complicate the interpretation of the earlier submillimetre observations of Cas A. Here we report far-infrared and molecular line observations that demonstrate that most of the detected submillimetre emission originates from interstellar dust in a molecular cloud complex located in the line of sight between the Earth and Cas A, and is therefore not associated with the remnant. The argument that type II supernovae produce copious amounts of dust is not supported by the case of Cas A, which previously appeared to provide the best evidence for this possibility.

Krause O; Birkmann SM; Rieke GH; Lemke D; Klaas U; Hines DC; Gordon KD

2004-12-01

204

New upper limit on intensity of forbidden Fe XIV 5303 in Tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] Analysis of a CCD image of the remnant of Tycho's supernova made in the forbidden coronal green line fails to reveal emission at a limit of 3.1 x 10 to the -8th ergs/sq cm s sr at the location of the reverse shock into the ejecta. The nondetection may imply that the reverse shock has not yet reached Fe-enriched ejecta or that the known clumpiness of the ejecta prevents production of observable amounts of Fe(+13). 19 refs

1990-01-01

205

First optical detection from the supernova remnant G 15.1-1.6  

CERN Multimedia

Deep optical CCD images of the supernova remnant G 15.1-1.6 were obtained and filamentary and diffuse emission has been discovered. The images, taken in the emission lines of Halpha+[N II], [S II] and [O III], reveal filamentary and diffuse structures all around the remnant. The radio emission at 4850 MHz in the same area is found to be well correlated with the brightest optical filaments. The IRAS 60 micron emission may also be correlated with the optical emission but to a lesser extent. The flux calibrated images suggest that the optical emission originates from shock-heated gas ([S II]/Halpha > 0.4), while there is a possible HII region ([S II]/Halpha ~0.3) contaminating the supernova remnant's emission to the east. Furthermore, deep long-slit spectra were taken at two bright filaments and also show that the emission originates from shock heated gas. An [O III] filamentary structure has also been detected further to the west but it lies outside the remnant's boundaries and possibly is not associated to it....

Boumis, P; Christopoulou, P E; Mavromatakis, F; Xilouris, E M; Goudis, C D

2008-01-01

206

Constraints on the Physics of Type Ia Supernovae from the X-Ray Spectrum of the Tycho Supernova Remnant  

CERN Document Server

In this paper we use high quality X-ray observations from XMM-Newton and Chandra to gain new insights into the explosion that originated Tycho's supernova 433 years ago. We perform a detailed comparison between the ejecta emission from the spatially integrated X-ray spectrum of the supernova remnant and current models for Type Ia supernova explosions. We use a grid of synthetic X-ray spectra based on hydrodynamic models of the evolution of the supernova remnant and self-consistent nonequilibrium ionization calculations for the state of the shocked plasma. We find that the fundamental properties of the X-ray emission in Tycho are well reproduced by a one-dimensional delayed detonation model with a kinetic energy of 1.2e51 erg. All the other paradigms for Type Ia explosions that we have tested fail to provide a good approximation to the observed ejecta emission, including one-dimensional deflagrations, pulsating delayed detonations and sub-Chandrasekhar explosions, as well as deflagration models calculated in t...

Badenes, C; Hughes, J P; Hwang, U; Bravo, E; Badenes, Carles; Borkowski, Kazimierz J.; Hughes, John P.; Hwang, Una; Bravo, Eduardo

2005-01-01

207

Supernova Remnants in the Magellanic Clouds. VI. The DEML316 Supernova Remnants  

CERN Multimedia

The DEML316 system contains two shells, both with the characteristic signatures of supernova remnants (SNRs). We analyze Chandra and XMM-Newton data for DEML316, investigating its spatial and spectral X-ray features. Our Chandra observations resolve the structure of the northeastern SNR (Shell A) as a bright inner ring and a set of "arcs" surrounded by fainter diffuse emission. The spectrum is well fit by a thermal plasma model with temperature ~1.4 keV; we do not find significant spectral differences for different regions of this SNR. The southwestern SNR (Shell B) exhibits an irregular X-ray outline, with a brighter interior ring of emission including a bright knot of emission. Overall the emission of the SNR is well described by a thermal plasma of temperature ~0.6 keV. The Bright Knot, however, is spectrally distinct from the rest of the SNR, requiring the addition of a high-energy spectral component consistent with a power-law spectrum of photon index 1.6--1.8. We confirm the findings of Nishiuchi et al....

Williams, R M

2005-01-01

208

The Expansion of the X-ray Remnant of Tycho's Supernova (SN1572)  

CERN Document Server

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 wave as compared to the reverse-shocked ejecta, an effect that has not been seen previously. The expansion parameter varies from $m=0.71\\pm0.06$ at the outermost edge of Tycho's supernova remnant (SNR) to a value of $m=0.34\\pm0.10$ on the inside edge of the bright rim of emission. These values are consistent with the rates expected for a remnant with constant density ejecta evolving into a uniform interstellar medium durin...

Hughes, J P

2000-01-01

209

Optical and Far-UV Spectroscopy of Knot D in the Vela Supernova Remnant  

CERN Document Server

We present spectra of optical filaments associated with the X-ray knot D in the Vela supernova remnant. It has been suggested that Knot D is formed by a bullet of supernova ejecta, that it is a break-out of the shock front of the Vela SNR, and also that it is an outflow from the recently discovered remnant RXJ0852.0-4622. We find that Knot D is a bow shock propagating into an interstellar cloud with normal abundances and typical cloud densities (n_H ~ 4-11 cm^-3). Optical longslit spectra show that the [S II] 6716,6731 to Halpha line ratio is greater than unity, proving that the optical filaments are shock excited. The analysis of far-ultraviolet spectra obtained with the Hopkins Ultraviolet Telescope and with the Far Ultraviolet Spectroscopic Explorer (FUSE) LWRS aperture show that slower shocks (~100 km s^-1) produce most of the low ionization lines such as O III] 1662, while faster shocks (~180 km s^-1) produce the O VI 1032,1038 and other high ionization lines. C III and O VI lines are also detected in th...

Sankrit, R; Raymond, J C; Sankrit, Ravi; Blair, William P.; Raymond, John C.

2003-01-01

210

The hydrodynamics of a supernova shock in the interstellar medium  

Science.gov (United States)

The interactions of a supernova blast wave with the inhomogeneities of the interstellar medium have been observed both in the young supernova remnants, with ages ˜; 102 yr, and in the middle-aged supernova remnants older than ˜ 104 yr. Low mass supernovae produce remnants interacting with an interstellar medium unaffected by the progenitor star, in which the density inhomogeneities mainly appear in the form of clouds. The encounter of the supernova shock with a cloud affects the propagation of the main shock and compresses and accelerates the cloud itself. In the adiabatic approximation, the cloud embedded by the blast wave becomes hydrodynamically unstable under the action of Rayleigh-Taylor and Kelvin-Helmoltz instabilities, adding mass to the intercloud medium. The thermal evaporation and radiative cooling further contribute to the energy and mass exchange between the cloud and the interstellar medium. Massive stars, such as progenitors of the supernovae, reprocess the interstellar medium, either ionizing the interstellar gas or by adding mass and kinetic energy via stellar winds. The supernova shock will move in a stratified medium and the remnant may be "muffled" by the circumstellar material disposed around the progenitor. Here we shall review the results of two-dimensional numerical hydrodynamics both in a cloudy and in a stratified medium comparing them with the observations in optical and X-ray bands for young (CAS-A) and evolved remnants (Cygnus Loop). Les interactions d'une onde de choc [blast wave] de supernova avec les inhomogénéité du milieu interstellaire ont été observées à la fois dans les résidus récents de supernova, d'environ 102 ans, et dans les résidus d'âge moyen, datant de plus de ˜104 ans. Les supernovae de petite masse générent des résidus qui interagissent avec un milieu interstellaire qui n'est pas affecté par l'étoile génératrice, dans laquelle les inhomogénéités en densité apparaissent principalement sous forme de nuages. La rencontre du choc d'une supernova avec un nuage affecte la propagation du choc principal, comprime et accélère le nuage lui-même. Dans l'approximation adiabatique, le nuage enveloppé par l'onde de choc devient hydrodynamiquement instable sous l'action des instabilités de Rayleigh-Thylor et Kelvin-Helmoltz, en ajoutant de la masse au milieu internuage. L'évaporation thermique et le refroidissement radiatif donnent une contribution ultérieure à l'échange d'énergie et de masse entre le nuage et le milieu interstellaire. Les étoiles massives, comme les générateurs de supernovae, régénèrent le milieu interstellaire, en ionisant le gaz interstellaire ou en ajoutant de la masse et de l'énergie cinétique par l'intermédiaire des vents stellaires. Le choc de supernova se propagera dans un milieu stratifié et le résidu peut être "emmitouflé" dans la matière circumstellaire disposée autour du générateur. Ici nous passerons en revue les résultats de l'hydrodynamique numérique à deux dimensions, dans un milieu soit nuageux soit stratifié, en les comparant avec les observations dans les bandes optiques et X pour les résidus jeunes (CAS-A) et évolués (Cygnus Loop).

Bedogni, R.

211

G306.3-0.9: A newly discovered young galactic supernova remnant  

CERN Multimedia

We present X-ray and radio observations of the new Galactic supernova remnant (SNR) G306.3-0.9, recently discovered by Swift. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array (ATCA) imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of ~ 160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24microns, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

Reynolds, Mark; Murphy, Tara; Miller, Jon; Maitra, Dipankar; Gultekin, Kayhan; Gehrels, Neil; Kennea, Jamie; Siegel, Michael; Gelbord, Jonathan; Kuin, Paul; Moss, Vanessa; Reeves, Sarah; Robbins, William; Gaensler, Bryan; Reis, Rubens; Petre, Robert

2013-01-01

212

Infrared echoes near the supernova remnant Cassiopeia A.  

Science.gov (United States)

Two images of Cassiopeia A obtained at 24 micrometers with the Spitzer Space Telescope over a 1-year time interval show moving structures outside the shell of the supernova remnant to a distance of more than 20 arc minutes. Individual features exhibit apparent motions of 10 to 20 arc seconds per year, independently confirmed by near-infrared observations. The observed tangential velocities are at roughly the speed of light. It is likely that the moving structures are infrared echoes, in which interstellar dust is heated by the explosion and by flares from the compact object near the center of the remnant. PMID:15947181

Krause, Oliver; Rieke, George H; Birkmann, Stephan M; Le Floc'h, Emeric; Gordon, Karl D; Egami, Eiichi; Bieging, John; Hughes, John P; Young, Erick T; Hinz, Joannah L; Quanz, Sascha P; Hines, Dean C

2005-06-10

213

Infrared echoes near the supernova remnant Cassiopeia A.  

UK PubMed Central (United Kingdom)

Two images of Cassiopeia A obtained at 24 micrometers with the Spitzer Space Telescope over a 1-year time interval show moving structures outside the shell of the supernova remnant to a distance of more than 20 arc minutes. Individual features exhibit apparent motions of 10 to 20 arc seconds per year, independently confirmed by near-infrared observations. The observed tangential velocities are at roughly the speed of light. It is likely that the moving structures are infrared echoes, in which interstellar dust is heated by the explosion and by flares from the compact object near the center of the remnant.

Krause O; Rieke GH; Birkmann SM; Le Floc'h E; Gordon KD; Egami E; Bieging J; Hughes JP; Young ET; Hinz JL; Quanz SP; Hines DC

2005-06-01

214

Simulation of the growth of the 3D Rayleigh-Taylor instability in supernova remnants using an expanding reference frame  

Science.gov (United States)

Context. The Rayleigh-Taylor instabilities that are generated by the deceleration of a supernova remnant during the ejecta-dominated phase are known to produce finger-like structures in the matter distribution that modify the geometry of the remnant. The morphology of supernova remnants is also expected to be modified when efficient particle acceleration occurs at their shocks. Aims: The impact of the Rayleigh-Taylor instabilities from the ejecta-dominated to the Sedov-Taylor phase is investigated over one octant of the supernova remnant. We also study the effect of efficient particle acceleration at the forward shock on the growth of the Rayleigh-Taylor instabilities. Methods: We modified the Adaptive Mesh Refinement code RAMSES to study with hydrodynamic numerical simulations the evolution of supernova remnants in the framework of an expanding reference frame. The adiabatic index of a relativistic gas between the forward shock and the contact discontinuity mimics the presence of accelerated particles. Results: The great advantage of the super-comoving coordinate system adopted here is that it minimizes numerical diffusion at the contact discontinuity, since it is stationary with respect to the grid. We propose an accurate expression for the growth of the Rayleigh-Taylor structures that smoothly connects the early growth to the asymptotic self-similar behaviour. Conclusions: The development of the Rayleigh-Taylor structures is affected, although not drastically, if the blast wave is dominated by cosmic rays. The amount of ejecta that reaches the shocked interstellar medium is smaller in this case. If acceleration were to occur at both shocks, the extent of the Rayleigh-Taylor structures would be similar but the reverse shock would be strongly perturbed.

Fraschetti, F.; Teyssier, R.; Ballet, J.; Decourchelle, A.

2010-06-01

215

Evolution of nonthermal supernova remnants. II. Can radio supernovae become plerions  

International Nuclear Information System (INIS)

[en] We discuss the evolution of pulsar-driven supernova remnants. It is shown that the early stages closely resemble the phenomenon of radio supernovae and that one can establish a direct evolutionary link between the two classes of objects. Light curves are obtained in the radio and the X-ray ranges under simple assumptions about the injected spectrum. The derived relations between surface brightness and diameter, both at low and at high frequencies, are compared with the observational data

1984-10-01

216

Evolution of nonthermal supernova remnants. II. Can radio supernovae become plerions  

Energy Technology Data Exchange (ETDEWEB)

We discuss the evolution of pulsar-driven supernova remnants. It is shown that the early stages closely resemble the phenomenon of radio supernovae and that one can establish a direct evolutionary link between the two classes of objects. Light curves are obtained in the radio and the X-ray ranges under simple assumptions about the injected spectrum. The derived relations between surface brightness and diameter, both at low and at high frequencies, are compared with the observational data.

Bandiera, R.; Pacini, F.; Salvati, M.

1984-10-01

217

Filamentary structure in Crab-like supernova remnants  

International Nuclear Information System (INIS)

It is shown that the most reasonable origin for filamentary structure in Crab-like supernova remnants is the Rayleigh-Taylor instability operating on thermal gas accelerated by the pulsar. The nonthermal filaments result from the interaction of the pulse-generated magnetic flux and relativistic particles with the thermal structures. This implies that 3C 58 should contain much as yet undetected gas. 44 references.

1988-01-01

218

GAMMA-RAY EMISSION OF ACCELERATED PARTICLES ESCAPING A SUPERNOVA REMNANT IN A MOLECULAR CLOUD  

International Nuclear Information System (INIS)

We present a model of gamma-ray emission from core-collapse supernovae (SNe) originating from the explosions of massive young stars. The fast forward shock of the supernova remnant (SNR) can accelerate particles by diffusive shock acceleration (DSA) in a cavern blown by a strong, pre-SN stellar wind. As a fundamental part of nonlinear DSA, some fraction of the accelerated particles escape the shock and interact with a surrounding massive dense shell producing hard photon emission. To calculate this emission, we have developed a new Monte Carlo technique for propagating the cosmic rays (CRs) produced by the forward shock of the SNR, into the dense, external material. This technique is incorporated in a hydrodynamic model of an evolving SNR which includes the nonlinear feedback of CRs on the SNR evolution, the production of escaping CRs along with those that remain trapped within the remnant, and the broadband emission of radiation from trapped and escaping CRs. While our combined CR-hydro-escape model is quite general and applies to both core collapse and thermonuclear SNe, the parameters we choose for our discussion here are more typical of SNRs from very massive stars whose emission spectra differ somewhat from those produced by lower mass progenitors directly interacting with a molecular cloud.

2011-04-20

219

Acceleration of cosmic rays by young core-collapse supernova remnants  

CERN Document Server

Context. Supernova Remnants (SNRs) are thought to be the primary candidates for the sources of Galactic cosmic rays. According to Diffusive Shock Acceleration theory, SNR shocks produce a power-law spectrum with index s = 2, perhaps non-linearly modified to harder spectra at high energy. Observations of SNRs often indicate particle spectra that are softer than that and show features not expected from classical theory. Known drawbacks of the standard approach are the assumption that SNRs evolve in a uniform environment, and that the reverse shock does not accelerate particles. Relaxing those assumptions increases the complexity of the problem, because one needs reliable hydrodynamical data for the plasma flow as well as good estimates for the magnetic field at the reverse shock. Aims. We show that these two factors are especially important when modeling young core-collapse SNRs that evolve in a complicated circumstellar medium shaped by the winds of progenitor stars. Methods. We use high-resolution numerical s...

Telezhinsky, I; Pohl, M

2012-01-01

220

High-Velocity Gas in the VELA Supernova Remnant  

Science.gov (United States)

We present high-resolution, high signal-to-noise spectra of the interstellar Na I and Ca II lines toward seven stars in the direction of the Vela supernova remnant. We show that high-velocity gas having a complex velocity structure exists toward these stars. A plot of the Log N(Ca II)/N(Na i) ratio as a function of velocity shows that the ratio increases monotonically as seen for local and low-density ISM sight lines, but there appears to be a decrease of about 0.5 dex in the ratio near ?100 km s-1 in the direction of the Vela SNR and other high-velocity gas regions. Several of the highest-velocity components toward the Vela stars have unusually small values of N(Ca II)/N (Na I) compared to moderate velocity components and provide interesting counterexamples to the "Roulty-Spitzer" effect. We suggest that these components are sites of post-shocked recombining gas in which pre-existing dust grains have not yet been completely destroyed. For several components, we detect time variability in the Na I and Ca II absorption line strengths, and for the high-velocity (?LSR?+190 km s-1) component toward RD 72997 we also see systematic velocity shifts in both the Na I and Ca II lines that imply the gas is being accelerated at the rate of ?1-2 km s-1 yr-1. Similarities in the structure, strength, and velocities of the high-velocity gas absorption toward three stars separated by less than 6' in IC 2395 suggest that some of the high-velocity gas in the Vela region may be accelerated by events other than the initial explosion that resulted in pulsar PSR 0833-045.

Danks, Anthony C.; Sembach, Kenneth R.

1995-06-01

 
 
 
 
221

Modelling Hard $\\gamma$-Ray Emission From Supernova Remnants  

CERN Document Server

The observation by the CANGAROO experiment of TeV emission from SN 1006, in conjunction with several instances of non-thermal X-ray emission from supernova remnants, has led to inferences of super-TeV electrons in these extended sources. While this is sufficient to propel the theoretical community in their modelling of particle acceleration and associated radiation, the anticipated emergence in the next decade of a number of new experiments probing the TeV and sub-TeV bands provides further substantial motivation for modellers. In particular, the quest for obtaining unambiguous gamma-ray signatures of cosmic ray ion acceleration defines a ``Holy Grail'' for observers and theorists alike. This review summarizes theoretical developments in the prediction of MeV-TeV gamma-rays from supernova remnants over the last five years, focusing on how global properties of models can impact, and be impacted by, hard gamma-ray observational programs, thereby probing the supernova remnant environment. Properties of central c...

Baring, M G

1999-01-01

222

Correlation of Supernova Remnant Masers and Gamma-Ray Sources  

CERN Multimedia

Supernova remnants interacting with molecular clouds are potentially exciting systems in which to detect evidence of cosmic ray acceleration. Prominent gamma-ray emission is produced via the decay of neutral pions when cosmic rays encounter the nearby dense clouds. In many of the supernova remnants coincident with gamma-ray sources, the presence of OH(1720 MHz) masers is used to identify interaction with dense gas and to provide a kinematic distance to the system. In this paper we use statistical tests to demonstrate that there is a correlation between these masers and a class of GeV- to TeV-energy gamma-ray sources coincident with interacting remnants. For pion decay, the gamma-ray luminosity provides a direct estimate of the local cosmic ray density. We find the cosmic ray density is enhanced by one to two orders of magnitude over the local solar value, comparable to X-ray-induced ionization in these remnants. The inferred ionization rates are sufficient to explain non-equilibrium chemistry in the post-shoc...

Hewitt, John W; Wardle, Mark

2009-01-01

223

Supernova Remnants and Plerions in the Compton Gamma-Ray Observatory Era  

CERN Document Server

Due to observations made by the Compton Gamma-Ray Observatory over the last six years, it appears that a number of galactic supernova remnants may be candidates for sources of cosmic gamma-rays. These include shell-type remnants such as IC443 and $\\gamma$ Cygni, which have no known parent pulsars, but have significant associations with unidentified EGRET sources, and others that appear to be composite, where a pulsar is embedded in a shell (e.g. W44 and Vela), or are purely pulsar-driven, such as the Crab Nebula. This review discusses our present understanding of gamma-ray production in plerionic and non-plerionic supernova remnants, and explores the relationship between such emission and that in other wavebands. Focuses include models of the Crab and Vela nebulae, the composite nature of W44, the relationship of shell-type remnants to cosmic ray production, the relative importance of shock-accelerated protons and electrons, constraints on models placed by TeV, X-ray and radio observations, and the role of el...

De Jager, O C; Jager, Ocker C. de; Baring, Matthew G.

1997-01-01

224

The Neutron Star Born in the Antlia Supernova Remnant  

CERN Multimedia

Among all known young nearby neutron stars, we search for the neutron star that was born in the same supernova event that formed the Antlia supernova remnant (SNR). We also look for a runaway star that could have been the former companion to the neutron star (if it exists) and then got ejected due to the same supernova. We find the pulsar PSR J0630-2834 to be the best candidate for a common origin with the Antlia SNR. In that scenario the SNR is ~1.2 Myr old and is presently located at a distance of ~138 pc. We consider the runaway star HIP 47155 a former companion candidate to PSR J0630-2834. The encounter time and place is consistent with both stars being ejected from the Antlia SNR. We measured the radial velocity of HIP 47155 as 32.42 +/- 0.70km/s.

Tetzlaff, Nina; Neuhaeuser, Ralph; Hohle, Markus Matthias

2013-01-01

225

EVIDENCE FOR PARTICLE ACCELERATION TO THE KNEE OF THE COSMIC RAY SPECTRUM IN TYCHO'S SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

[en] Supernova remnants (SNRs) have long been assumed to be the source of cosmic rays (CRs) up to the 'knee' of the CR spectrum at 1015 eV, accelerating particles to relativistic energies in their blast waves by the process of diffusive shock acceleration (DSA). Since CR nuclei do not radiate efficiently, their presence must be inferred indirectly. Previous theoretical calculations and X-ray observations show that CR acceleration significantly modifies the structure of the SNR and greatly amplifies the interstellar magnetic field. We present new, deep X-ray observations of the remnant of Tycho's supernova (SN 1572, henceforth Tycho), which reveal a previously unknown, strikingly ordered pattern of non-thermal high-emissivity stripes in the projected interior of the remnant, with spacing that corresponds to the gyroradii of 1014-1015 eV protons. Spectroscopy of the stripes shows the plasma to be highly turbulent on the (smaller) scale of the Larmor radii of TeV energy electrons. Models of the shock amplification of magnetic fields produce structure on the scale of the gyroradius of the highest energy CRs present, but they do not predict the highly ordered pattern we observe. We interpret the stripes as evidence for acceleration of particles to near the knee of the CR spectrum in regions of enhanced magnetic turbulence, while the observed highly ordered pattern of these features provides a new challenge to models of DSA.

2011-02-20

226

Evidence For Particle Acceleration to the Knee of the Cosmic Ray Spectrum in Tycho's Supernova Remnant  

CERN Document Server

Supernova remnants (SNRs) have long been assumed to be the source of cosmic rays (CRs) up to the "knee" of the CR spectrum at 10^15 eV, accelerating particles to relativistic energies in their blast waves by the process of diffusive shock acceleration (DSA). Since cosmic ray nuclei do not radiate efficiently, their presence must be inferred indirectly. Previous theoretical calculations and X-ray observations show that CR acceleration modifies significantly the structure of the SNR and greatly amplifies the interstellar magnetic field. We present new, deep X-ray observations of the remnant of Tycho's supernova (SN 1572, henceforth Tycho), which reveal a previously unknown, strikingly ordered pattern of non-thermal high-emissivity stripes in the projected interior of the remnant, with spacing that corresponds to the gyroradii of 10^14 - 10^15 eV} protons. Spectroscopy of the stripes shows the plasma to be highly turbulent on the (smaller) scale of the Larmor radii of TeV energy electrons. Models of the shock am...

Eriksen, Kristoffer A; Badenes, Carles; Fesen, Robert; Ghavamian, Parviz; Moffett, David; Plucinsky, Paul P; Rakowski, Cara E; Reynoso, Estela M; Slane, Patrick

2011-01-01

227

Spitzer observations of the N157B supernova remnant and its surroundings  

Science.gov (United States)

Aims: We study the LMC interstellar medium in the field of the nebula N157B, which contains a supernova remnant, an OB association, ionized gas, and high-density dusty filaments in close proximity. We investigate the relative importance of shock excitation by the SNR and photo-ionization by the OB stars, as well as possible interactions between the supernova remnant and its environment. Methods: We apply multiwavelength mapping and photometry, along with spatially resolved infrared spectroscopy, to identifying the nature of the ISM using new infrared data from the Spitzer space observatory and X-ray, optical, and radio data from the literature. Results: The N157B SNR has no infrared counterpart. Infrared emission from the region is dominated by the compact blister-type HII region associated with 2MASS J05375027-6911071 and excited by an O8-O9 star. This object is part of an extended infrared emission region that is associated with a molecular cloud. We find only weak emission from the shock-indicator [FeII], and both the excitation and the heating of the extended cloud are dominated by photo-ionization by the early O stars of LH 99. Conclusions: Any possible impact by the expanding SNR does not now affect the extended cloud of molecules and dust, despite the apparent overlap of SNR X-ray emission with infrared and H? emission from the cloud. This implies that the supernova progenitor cannot have been more massive than about 25 M?.

Micelotta, E. R.; Brandl, B. R.; Israel, F. P.

2009-06-01

228

Nonthermal radiation from supernova remnants in the adiabatic stage of evolution  

Energy Technology Data Exchange (ETDEWEB)

We develop a physically self-consistent model for nonthermal radiation from supernova remnants in the adiabatic blast-wave (Sedov) phase of evolution, assuming relativistic electrons are accelerated in the shock to an energy density proportional to the postshock pressure, and that the magnetic field is either compressed ambient field or turbulently amplified. We have compared the resulting synchrotron profiles with observations of Tycho's remnant and find the amplified magnetic field model gives an adequate fit if there is a small radially ordered component of the magnetic field at the shock wave. The model predicts that surface brightness of Tycho declines as (diameter)/sup -4.4/ and that the flux declines by 0.25% per year. We explain the featureless power-law X-ray spectrum of the SN 1006 remnant as the extension of the radio emission: the entire spectrum can be fitted when synchrotron losses are included. The model implies that while several percent of the shock energy goes into The magnetic field, only 2 x 10/sup -5/ of the shock energy goes into relativistic electrons.

Reynolds, S.P.; Chevalier, R.A.

1981-05-01

229

Nonthermal radiation from supernova remnants in the adiabatic stage of evolution  

International Nuclear Information System (INIS)

[en] We develop a physically self-consistent model for nonthermal radiation from supernova remnants in the adiabatic blast-wave (Sedov) phase of evolution, assuming relativistic electrons are accelerated in the shock to an energy density proportional to the postshock pressure, and that the magnetic field is either compressed ambient field or turbulently amplified. We have compared the resulting synchrotron profiles with observations of Tycho's remnant and find the amplified magnetic field model gives an adequate fit if there is a small radially ordered component of the magnetic field at the shock wave. The model predicts that surface brightness of Tycho declines as (diameter)/sup -4.4/ and that the flux declines by 0.25% per year. We explain the featureless power-law X-ray spectrum of the SN 1006 remnant as the extension of the radio emission: the entire spectrum can be fitted when synchrotron losses are included. The model implies that while several percent of the shock energy goes into The magnetic field, only 2 x 10-5 of the shock energy goes into relativistic electrons

1981-05-01

230

X-ray studies of supernova remnants: A different view of supernova explosions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The unprecedented spatial and spectral resolutions of Chandra have revolutionized our view of the X-ray emission from supernova remnants. The excellent datasets accumulated on young, ejecta-dominated objects like Cas A or Tycho present a unique opportunity to study at the same time the chemical and ...

Badenes, Carles

231

X-ray spectra of young type I supernova remnants: Exploded white dwarfs  

Energy Technology Data Exchange (ETDEWEB)

We argue that the X-ray spectra of young Type I supernova remnants can be understood consistently in terms of thermal emission mainly from a reverse shock into initially uniform density ejecta. The inferred mass of ejecta is then consistent with 1.4 M/sub sun/ in SN 1006, Tycho, and Kepler. A substantial mass of iron, perhaps approx.0.8 M/sub sun/, may be present provided that the ejecta are chemically inhomogeneous, with iron confined to inner layers of ejecta. The marked difference between the X-ray spectra of SN 1006 and Tycho is explained by the lower interstellar density around SN 1006.

Hamilton, A.J.S.; Sarazin, C.L.; Szymkowiak, A.E.; Vartanian, M.H.

1985-10-01

232

X-ray spectra of young type I supernova remnants: Exploded white dwarfs  

International Nuclear Information System (INIS)

[en] We argue that the X-ray spectra of young Type I supernova remnants can be understood consistently in terms of thermal emission mainly from a reverse shock into initially uniform density ejecta. The inferred mass of ejecta is then consistent with 1.4 M/sub sun/ in SN 1006, Tycho, and Kepler. A substantial mass of iron, perhaps approx.0.8 M/sub sun/, may be present provided that the ejecta are chemically inhomogeneous, with iron confined to inner layers of ejecta. The marked difference between the X-ray spectra of SN 1006 and Tycho is explained by the lower interstellar density around SN 1006

1985-10-01

233

Supernova remnants interacting with molecular clouds as seen with H.E.S.S  

CERN Document Server

About 30 Galactic supernova remnants (SNRs) are thought to be physically associated with molecular clouds (MCs). These systems are prime \\g-ray source candidates as the accelerated particles from shock fronts collide with the surrounding high-density medium thus emitting gamma-rays through hadronic interactions. However only a handful of such interacting SNRs are detected at TeV energies. We report the current status of the High Energy Stereoscopic System (H.E.S.S.) observations towards these SNR-MC systems, with a particular emphasis on the latest results.

Fernandez, D; Eger, P; Laffon, H; Mehault, J; Ohm, S; Oya, I

2013-01-01

234

X-ray Observations of Vela Supernova Remnant Ejecta Fragments  

Science.gov (United States)

As one of the nearest SNRs, the Vela Supernova Remnant (SNR) subtends more than 8 degrees on the sky, making it ideal for spatially resolved spectral studies. Its environment is complex, and the remnant shows marked variations: the remnant is bright, soft, and sharply defined to the east and north, but much fainter and less well ordered in the west and south. Age estimates for the associated pulsar range from $\\sim11400$ years to as much as 18000 years, making the the SNR a moderately old remnant. The remnant shows curious protrusions beyond the projected rim (Aschenbach et al. 1995, Nature 373, 587). Many have subsequently been investigated in X-rays and in each case, enhanced abundances have been detected, confirming that these fragments include ejecta. Here, we present analyses of several ejecta fragments based on Suzaku and XMM-Newton X-ray observations. This work was supported by NASA grants NNX06AE40G, NNX07AF67G, NNX08AZ74G, and by NASA contract NAS8-03060.

Gaetz, Terrance J.

2012-05-01

235

Very high resolution calculations of very young supernova remnants  

International Nuclear Information System (INIS)

After the supernova shock wave has swepted up about 8 to 10 stellar masses of interstellar material, the SNR structure is well described by blast wave theory. In fact, both numerical calculations of the early phases and small scale, laboratory simulations show transition to blast wave at 8 to 10 masses. In hindsight, we now know that the transition region between the photosphere (roughly 10-9 g/cm3) and the circumstellar medium (10-24 g/cm3) plays a crucial role. The shock wave is strongly accelerated down the density gradient, putting the shocked material behind into free expansion. When the shock encounters circumstellar material, it begins to decelerate. A second, reverse shock propagates into the stellar material that plows into the shocked circumstellar gas. All this happens on a timescale of days. The first attempts to include a description of the outer stellar envelop were aimed at analysis of the uv and X-Ray bursts produced when the shock wave reaches the photosphere. Falk and Arnett terminated their calculations before the shock reached the circumstellar gas. Chevalier mentions a reverse shock forming early but did not go into any details. We noticed and described the double-shock structure but, in hindsight, lacked sufficient resolution to produce the detailed structure between the shocks. Chevalier derived a similarity solution for the intershock region. In this paper we describe very high resolution calculations which reproduce and confirm the Chevalier similarity solution.

1982-09-02

236

On the Nonthermal Emission from the Supernova Remnant W51C  

CERN Multimedia

The middle-aged supernova remnant (SNR) W51C is an interesting source for the interaction of the shell with a molecular cloud. The shell emits intense radio synchrotron photons, and high-energy gamma-rays from the remnant have been detected using the {\\it Fermi} Large Area Telescope (LAT), the H.E.S.S. telescope, and the Milagro gamma-ray observatory. Based on a semi-analytical approach to the nonlinear shock acceleration process, we investigate the multiband nonthermal emission from W51C. The result shows that the radio emission from the remnant can be explained as synchrotron radiation of the electrons accelerated by a part of the shock flowing into the ambient medium. On the other hand, the high-energy gamma-rays detected by the {\\it Fermi} LAT are mainly produced via proton-proton collisions of the high-energy protons with the ambient matter in the molecular cloud overtaken by the other part of the shock. We propose a possible explanation of the multiband nonthermal emission from W51C, and it can be concl...

Fang, Jun

2010-01-01

237

A CHANDRA X-RAY SURVEY OF EJECTA IN THE CASSIOPEIA A SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

We present a survey of the X-ray-emitting ejecta in the Cassiopeia A supernova remnant (SNR) based on an extensive analysis of over 6000 spectral regions extracted on 2.''5-10'' angular scales using the Chandra 1 Ms observation. We interpret these results in the context of hydrodynamical models for the evolution of the remnant. The distributions of fitted temperature and ionization age, and the implied mass coordinates, are highly peaked and suggest that the ejecta were subjected to multiple secondary shocks following reverse shock interaction with ejecta inhomogeneities. Based on the fitted emission measure and element abundances, and an estimate of the emitting volume, we derive masses for the X-ray-emitting ejecta and also show the distribution of the mass of various elements over the remnant. An upper limit to the total shocked Fe mass visible in X-rays appears to be roughly 0.13 M?, which accounts for nearly all of the mass expected in Fe ejecta. We find two populations of Fe ejecta, that associated with normal Si burning and that possibly associated with ?-rich freezeout, with a mass ratio of approximately 2:1. Essentially all of the observed Fe (both components) lies well outside the central regions of the SNR, possibly having been ejected by hydrodynamic instabilities during the explosion. We discuss this and its implications for the neutron star kick.

2012-02-20

238

Evolution of Supernova Remnants Expanding out of the Dense Circumstellar Matter into the Rarefied Interstellar Medium  

CERN Document Server

We carry out 3D-hydrodynamical calculations for the interaction of expanding supernova ejecta with the dense circumstellar matter (CSM) and the rarefied interstellar medium (ISM) outside. The CSM is composed of the stellar wind matter from the progenitor in its pre-supernova phase, and assumed to be axially symmetric: more matter around the equator than in the polar direction driven by rotation of the progenitor. Because of high density of the CSM, the ionization state of the shock-heated ejecta quickly becomes equilibrium with the electron temperature. When the blast wave breaks out of the CSM into the rarefied ISM, the shocked ejecta cools rapidly due to adiabatic expansion, and hence an over-ionized/recombining plasma would be left. The ejecta is reheated by the second reverse shock due to the interaction with the ISM. We calculate the emission measure of the supernova remnant (SNR) along the line of sight, and find that the over-ionized plasma appears to be bar-like with wings in the edge-on (equatorial v...

Shimizu, Takafumi; Koyama, Katsuji

2011-01-01

239

EXPANSION OF THE YOUNGEST GALACTIC SUPERNOVA REMNANT G1.9+0.3  

International Nuclear Information System (INIS)

We present a measurement of the expansion and brightening of G1.9 + 0.3, the youngest Galactic supernova remnant (SNR), comparing Chandra X-ray images obtained in 2007 and 2009. A simple uniform-expansion model describes the data well, giving an expansion rate of 0.642% ± 0.049% yr-1 and a flux increase of 1.7% ± 1.0% yr-1. Without deceleration, the remnant age would then be 156 ± 11 yr, consistent with earlier results. Since deceleration must have occurred, this age is an upper limit; we estimate an age of about 110 yr or an explosion date of about 1900. The flux increase is comparable to reported increases at radio wavelengths. G1.9+0.3 is the only Galactic SNR increasing in flux, with implications for the physics of electron acceleration in shock waves.

240

COSMIC-RAY ELECTRON EVOLUTION IN THE SUPERNOVA REMNANT RX J1713.7-3946  

Energy Technology Data Exchange (ETDEWEB)

A simple formalism to describe nonthermal electron acceleration, evolution, and radiation in supernova remnants (SNRs) is presented. The electron continuity equation is analytically solved assuming that the nonthermal electron injection power is proportional to the rate at which the kinetic energy of matter is swept up in an adiabatically expanding SNR shell. We apply this model to Fermi and HESS data from the SNR RX J1713.7-3946 and find that a one-zone leptonic model with Compton-scattered cosmic microwave background and interstellar infrared photons has difficulty providing a good fit to its spectral energy distribution, provided the source is at a distance {approx}1 kpc from the Earth. However, the inclusion of multiple zones, as hinted at by recent Chandra observations, does provide a good fit, but requires a second zone of compact knots with magnetic fields B {approx} 16 {mu}G, comparable to shock-compressed fields found in the bulk of the remnant.

Finke, Justin D.; Dermer, Charles D., E-mail: justin.finke@nrl.navy.mil [U.S. Naval Research Laboratory, Code 7653, 4555 Overlook Ave. SW, Washington, DC 20375-5352 (United States)

2012-05-20

 
 
 
 
241

The population of supernova remnants in the Magellanic Clouds  

CERN Multimedia

The detection of SNRs in the Magellanic Clouds is reviewed with emphasis on its limits. A sample of SNRs is then used to derive the mean interval between SN explosions, tau . After the maximum constraints have been put on all the other parameters, the distribution of diameters of remnants with diameter less than 30 pc in the LMC is shown to agree well with theoretical predictions. In adopting a mean value of E/sub 0//n/sub 0/ (energy at explosion over surrounding density) of 5*10/sup 51/ ergs cm/sup 3/, the best value of tau is 300+or-100 years in good agreement with predictions from statistics of supernovae in external galaxies. The small number of remnants in the SMC prevents a similar approach being used with any statistical significance. (20 refs).

Dennefeld, M

1978-01-01

242

Radio structure of the remnant of Tycho's supernova (SN 1572)  

International Nuclear Information System (INIS)

[en] The radio emission from the remnant of Tycho's supernova of 1572 arises in a nearly circular, clumpy shell. A very distinct, thin bright rim just outside the main shell can be seen around most of the periphery of the remnant. The outer edge of radio emission, usually defined by this bright rim, coincides perfectly with the outer X-ray boundary. Most of the emission is polarized by a modest amount, with the outer rim particularly prominent. Observations at several wavelengths are used to map out the rotation measure at high angular resolution, and determine the intrinsic magnetic field direction. The magnetic field shows a somewhat cellular pattern but with a net radial orientation and a generally fairly low degree of polarization. 44 refs

1991-01-01

243

EVOLUTION OF SYNCHROTRON X-RAYS IN SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

A systematic study of the synchrotron X-ray emission from supernova remnants (SNRs) has been conducted. We selected a total of 12 SNRs whose synchrotron X-ray spectral parameters are available in the literature with reasonable accuracy and studied how their luminosities change as a function of radius. It is found that the synchrotron X-ray luminosity tends to drop especially when the SNRs become larger than ?5 pc, despite large scatter. This may be explained by the change of spectral shape caused by the decrease of the synchrotron roll-off energy. A simple evolutionary model of the X-ray luminosity is proposed and is found to reproduce the observed data approximately, with reasonable model parameters. According to the model, the total energy of accelerated electrons is estimated to be 1047-48 erg, which is well below the supernova explosion energy. The maximum energies of accelerated electrons and protons are also discussed.

2012-02-20

244

Evolution of Synchrotron X-rays in Supernova Remnants  

CERN Document Server

A systematic study of the synchrotron X-ray emission from supernova remnants (SNRs) has been conducted. We selected a total of 12 SNRs whose synchrotron X-ray spectral parameters are available in the literature with reasonable accuracy, and studied how their luminosities change as a function of radius. It is found that the synchrotron X-ray luminosity tends to drop especially when the SNRs become larger than ~5 pc, despite large scatter. This may be explained by the change of spectral shape caused by the decrease of the synchrotron roll-off energy. A simple evolutionary model of the X-ray luminosity is proposed and is found to reproduce the observed data approximately, with reasonable model parameters. According to the model, the total energy of accelerated electrons is estimated to be 10^(47-48) ergs, which is well below the supernova explosion energy. The maximum energies of accelerated electrons and protons are also discussed.

Nakamura, Ryoko; Dotani, Tadayasu; Ishida, Manabu; Yamazaki, Ryo; Kohri, Kazunori

2011-01-01

245

EVOLUTION OF SYNCHROTRON X-RAYS IN SUPERNOVA REMNANTS  

Energy Technology Data Exchange (ETDEWEB)

A systematic study of the synchrotron X-ray emission from supernova remnants (SNRs) has been conducted. We selected a total of 12 SNRs whose synchrotron X-ray spectral parameters are available in the literature with reasonable accuracy and studied how their luminosities change as a function of radius. It is found that the synchrotron X-ray luminosity tends to drop especially when the SNRs become larger than {approx}5 pc, despite large scatter. This may be explained by the change of spectral shape caused by the decrease of the synchrotron roll-off energy. A simple evolutionary model of the X-ray luminosity is proposed and is found to reproduce the observed data approximately, with reasonable model parameters. According to the model, the total energy of accelerated electrons is estimated to be 10{sup 47-48} erg, which is well below the supernova explosion energy. The maximum energies of accelerated electrons and protons are also discussed.

Nakamura, Ryoko; Bamba, Aya; Dotani, Tadayasu; Ishida, Manabu [ISAS/JAXA Department of High Energy Astrophysics, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Yamazaki, Ryo [Department of Physics and Mathematics, Aoyama-Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 252-5258 (Japan); Kohri, Kazunori [Theory Center, Institute of Particle and Nuclear Studies, KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba 305-0801 (Japan)

2012-02-20

246

High-energy antiprotons from old supernova remnants.  

Science.gov (United States)

A recently proposed model explains the rise in energy of the positron fraction measured by the PAMELA satellite in terms of hadronic production of positrons in aged supernova remnants, and acceleration therein. Here we present a preliminary calculation of the antiproton flux produced by the same mechanism. While the model is consistent with present data, a rise of the antiproton to proton ratio is predicted at high energy, which strikingly distinguishes this scenario from other astrophysical explanations of the positron fraction (such as pulsars). We briefly discuss important implications for dark matter searches via antimatter. PMID:19792708

Blasi, Pasquale; Serpico, Pasquale D

2009-08-21

247

High-energy antiprotons from old supernova remnants.  

UK PubMed Central (United Kingdom)

A recently proposed model explains the rise in energy of the positron fraction measured by the PAMELA satellite in terms of hadronic production of positrons in aged supernova remnants, and acceleration therein. Here we present a preliminary calculation of the antiproton flux produced by the same mechanism. While the model is consistent with present data, a rise of the antiproton to proton ratio is predicted at high energy, which strikingly distinguishes this scenario from other astrophysical explanations of the positron fraction (such as pulsars). We briefly discuss important implications for dark matter searches via antimatter.

Blasi P; Serpico PD

2009-08-01

248

High-energy antiprotons from old supernova remnants  

CERN Multimedia

A recently proposed model (arXiv:0903.2794) explains the rise in energy of the positron fraction measured by the PAMELA satellite in terms of hadronic production of positrons in aged supernova remnants, and acceleration therein. Here we present a preliminary calculation of the anti-proton flux produced by the same mechanism. While the model is consistent with present data, a rise of the antiproton to proton ratio is predicted at high energy, which strikingly distinguishes this scenario from other astrophysical explanations of the positron fraction (like pulsars). We briefly discuss important implications for Dark Matter searches via antimatter.

Blasi, Pasquale

2009-01-01

249

Observations of the supernova remnant W28 at TeV energies  

CERN Document Server

The atmospheric Cerenkov imaging technique has been used to search for point-like and diffuse TeV gamma-ray emission from the southern supernova remnant, W28, and surrounding region. The search, made with the CANGAROO 3.8m telescope, encompasses a number of interesting features, the supernova remnant itself, the EGRET source 3EG J1800-2338, the pulsar PSR J1801-23, strong 1720 MHz OH masers and molecular clouds on the north and east boundaries of the remnant. An analysis tailored to extended and off-axis point sources was used, and no evidence for TeV gamma-ray emission from any of the features described above was found in data taken over the 1994 and 1995 seasons. Our upper limit (E>1.5 TeV) for a diffuse source of radius 0.25deg encompassing both molecular clouds was calculated at 6.64e-12 photons cm^-2 s^-1 (from 1994 data), and interpreted within the framework of a model predicting TeV gamma-rays from shocked-accelerated hadrons. Our upper limit suggests the need for some cutoff in the parent spectrum of ...

Rowell, G P; Dazeley, S A; Edwards, P G; Gunji, S; Hara, T; Holder, J; Kawachi, A; Kifune, T; Matsubara, Y; Mizumoto, Y; Mori, M; Muraishi, H; Muraki, Y; Nishijima, K; Ogio, S; Patterson, J R; Roberts, M D; Sako, T; Sakurazawa, K; Susukita, R; Tamura, T; Tanimori, T; Thornton, G J; Yanagita, S; Yoshida, T; Yoshikoshi, T

2000-01-01

250

Spitzer observations of the N157B supernova remnant and its surroundings  

CERN Multimedia

(Aims): We study the LMC interstellar medium in the field of the nebula N157B, which contains a supernova remnant, an OB association, ionized gas, and high-density dusty filaments in close proximity. We investigate the relative importance of shock excitation by the SNR and photo-ionization by the OB stars, as well as possible interactions between the supernova remnant and its environment. (Methods): We apply multiwavelength mapping and photometry, along with spatially resolved infrared spectroscopy, to identifying the nature of the ISM using new infrared data from the Spitzer space observatory and X-ray, optical, and radio data from the literature. (Results): The N157B SNR has no infrared counterpart. Infrared emission from the region is dominated by the compact blister-type HII region associated with 2MASS J05375027-6911071 and excited by an O8-O9 star. This object is part of an extended infrared emission region that is associated with a molecular cloud. We find only weak emission from the shock-indicator [F...

Micelotta, E R; Israel, F P; 10.1051/0004-6361/200809849

2009-01-01

251

High-Energy Emission from the Composite Supernova Remnant MSH 15-56  

CERN Document Server

MSH 15-56 (G326.3-1.8) is a composite supernova remnant (SNR) that consists of an SNR shell and a displaced pulsar wind nebula (PWN) in the radio. We present XMM-Newton and Chandra X-ray observations of the remnant that reveal a compact source at the tip of the radio PWN and complex structures that provide evidence for mixing of the supernova (SN) ejecta with PWN material following a reverse shock interaction. The X-ray spectra are well fitted by a non-thermal power-law model whose photon index steepens with distance from the presumed pulsar, and a thermal component with an average temperature of 0.55 keV. The enhanced abundances of silicon and sulfur in some regions, and the similar temperature and ionization timescale, suggest that much of the X-ray emission can be attributed to SN ejecta that have either been heated by the reverse shock or swept up by the PWN. We find one region with a lower temperature of 0.3 keV that appears to be in ionization equilibrium. Assuming the Sedov model, we derive a number of...

Temim, Tea; Castro, Daniel; Plucinsky, Paul; Gelfand, Joseph; Dickel, John R

2013-01-01

252

Optical observations of the morphology and kinematics of the compact core of the peculiar supernova remnant CTB 80  

Energy Technology Data Exchange (ETDEWEB)

Optical observations of the 1-arcmin core of the complex supernova remnant CTB 80 have been made with the Manchester echelle spectrometer, in both its imaging and spectral modes, on the Isaac Newton and William Herschel telescopes. Four 'shells' (A-D) are found in the light of H/alpha/ but only the central two of these (A and B) are bright at (N II). Ionization by shocks of shells with different velocities is implied. (author).

Whitehead, M.J.; Meaburn, J.; Clayton, C.A.

1989-04-15

253

SPITZER OBSERVATIONS OF DUST DESTRUCTION IN THE PUPPIS A SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

The interaction of the Puppis A supernova remnant (SNR) with a neighboring molecular cloud provides a unique opportunity to measure the amount of grain destruction in an SNR shock. Spitzer Space Telescope MIPS imaging of the entire SNR at 24, 70, and 160 ?m shows an extremely good correlation with X-ray emission, indicating that the SNR's IR radiation is dominated by the thermal emission of swept-up interstellar dust, collisionally heated by the hot shocked gas. Spitzer IRS spectral observations targeted both the Bright Eastern Knot (BEK) of the SNR where a small cloud has been engulfed by the supernova blast wave and outlying portions of the associated molecular cloud that are yet to be hit by the shock front. Modeling the spectra from both regions reveals the composition and the grain size distribution of the interstellar dust, both in front of and behind the SNR shock front. The comparison shows that the ubiquitous polycyclic aromatic hydrocarbons of the interstellar medium are destroyed within the BEK, along with nearly 25% of the mass of graphite and silicate dust grains.

2010-12-10

254

Neutrino signatures of supernova shock and reverse shock propagation  

CERN Document Server

A few seconds after bounce in a core-collapse supernova, the shock wave passes the density region corresponding to resonant neutrino oscillations with the ``atmospheric'' neutrino mass difference. The transient violation of the adiabaticity condition manifests itself in an observable modulation of the neutrino signal from a future galactic supernova. In addition to the shock wave propagation effects that were previously studied, a reverse shock forms when the supersonically expanding neutrino-driven wind collides with the slower earlier supernova ejecta. This implies that for some period the neutrinos pass two subsequent density discontinuities, giving rise to a ``double dip'' feature in the average neutrino energy as a function of time. We study this effect both analytically and numerically and find that it allows one to trace the positions of the forward and reverse shocks. We show that the energy dependent neutrino conversion probabilities allow one to detect oscillations even if the energy spectra of diff...

Tomás, R; Raffelt, Georg G; Dighe, Amol S; Janka, H T; Scheck, L

2004-01-01

255

Far Ultraviolet Spectroscopic Explorer Survey of Magellanic Cloud Supernova Remnants  

CERN Document Server

We report the progress to date from an ongoing unbiased ultraviolet survey of supernova remnants in the Magellanic Clouds using the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. This survey is obtaining spectra of a random large sample of Magellanic Cloud supernova remnants with a broad range of radio, optical, and X-ray properties. To date, 39 objects have been observed in the survey (38 in the LMC and one in the SMC) and 15 have been detected, a detection rate of nearly 40%. Our survey has nearly tripled the number of UV-detected SNRs in the Magellanic Clouds (from 8 to 22). Because of the diffuse source sensitivity of FUSE, upper limits on non-detected objects are quite sensitive in many cases. Estimated total luminosities in O~VI span a broad range from considerably brighter to many times fainter than the inferred soft X-ray luminosities, indicating that O~VI can be an important and largely unrecognized coolant in certain objects. We compare the optical and X-ray properties of the detected and ...

Blair, W P; Sankrit, R; Danforth, C W; Blair, William P.; Ghavamian, Parviz; Sankrit, Ravi; Danforth, Charles W.

2006-01-01

256

Alfven Wave Amplification and Self-Containment of Cosmic-Rays Escaping from a Supernova Remnant  

CERN Multimedia

We study the escape of cosmic-ray (CR) protons accelerated at a supernova remnant (SNR) by numerically solving a diffusion-convection equation from the vicinity of the shock front to the region far away from the front. We consider the amplifications of Alfven waves generated by the escaping CR particles and their effects on CR escape into interstellar medium (ISM). We find that the amplification of the waves significantly delays the escape of the particles even far away from the shock front (on a scale of the SNR). This means that the energy spectrum of CR particles measured through gamma-ray observations at molecular clouds around SNRs is seriously affected by the particle scattering by the waves.

Fujita, Yutaka; Ohira, Yutaka; Iwasaki, Kazunari

2011-01-01

257

Antimatter spectra from a time-dependent modeling of supernova remnants  

International Nuclear Information System (INIS)

We calculate the energy spectra of cosmic rays (CR) and their secondaries produced in a supernova remnant (SNR), taking into account the time-dependence of the SNR shock. We model the trajectories of charged particles as a random walk with a prescribed diffusion coefficient, accelerating the particles at each shock crossing. Secondary production by CRs colliding with gas is included as a Monte Carlo process. We find that SNRs produce less antimatter than suggested previously: The positron/electron ratio Fe+ Fe++e- and the antiproton/proton ratio F p-bar /Fp-bar+p are a few percent and few x10-5, respectively. Both ratios do not rise with energy.

2010-11-01

258

An extended source of GeV gamma rays coincident with the supernova remnant HB 21  

CERN Multimedia

We analyse 3.5 years of public Fermi/LAT data around the position of the supernova remnant HB 21, where four point-like sources from the 2nd Fermi/LAT catalog are found. We detect an extended gamma-ray source coincident with the shell observed at radio wavelengths. The morphological modelling favours a uniform circle as best template for the observed emission. The spectral energy distribution is best described by a curved power law, with a maximum at $0.413\\pm0.019$\\,GeV. Dividing the circle in three regions coincident with previously identified shocked molecular clouds, we find indications that one of this regions has a softer spectrum. Combining this information with the morphology above 3\\,GeV, we suggest that the gamma-ray emission from HB 21 can be understood as a combination of emission from the shell itself plus emission from shocked/illuminated molecular clouds.

Reichardt, Ignasi; Rico, Javier; Yang, Ruizhi

2012-01-01

259

The Chemical Abundances of Tycho G in Supernova Remnant 1572  

CERN Multimedia

We present an analysis of the chemical abundances of the star Tycho G in the direction of the remnant of supernova (SN) 1572, based on Keck high-resolution optical spectra. The stellar parameters of this star are found to be those of a G-type subgiant with $T_{\\mathrm{eff}} = 5900 \\pm 100$ K, \\loggl $ = 3.85 \\pm 0.30$ dex, and $\\mathrm{[Fe/H]} = -0.05 \\pm 0.09$. This determination agrees with the stellar parameters derived for the star in a previous survey for the possible companion star of SN 1572 (Ruiz-Lapuente et al. 2004). The chemical abundances follow the Galactic trends, except for Ni, which is overabundant relative to Fe, $[{\\rm Ni/Fe}] $ $=$ 0.16 $\\pm$ 0.04. Co is slightly overabundant (at a low significance level). These enhancements in Fe-peak elements could have originated from pollution by the supernova ejecta. We find a surprisingly high Li abundance for a star that has evolved away from the main sequence. We discuss these findings in the context of companion stars of supernovae.

Hernández, Jonay I González; Filippenko, Alexei V; Foley, Ryan J; Gal-Yam, Avishay; Simon, Joshua D

2008-01-01

260

Neutrino emission from a supernova shock  

International Nuclear Information System (INIS)

[en] In the shock resulting from the ''bounce'' of a supernova, the neutrinos are prevented from leaving by the high neutrino opacity of the material just outside the shock, until the density of that material has decreased to less than 1011 g cm-3. The number of neutrinos then emitted is moderate. Neutrino pairs are formed, mainly from electron pairs, and their emission again is limited by the opacity. The energy lost from the shock by neutrino pairs is estimated, and is from 20 to 50% for reasonable initial shock energies

1980-10-01

 
 
 
 
261

Expansion of the supernova remnant 3C 10 (Tycho) and its implications for models of young remnants  

International Nuclear Information System (INIS)

The remnant of Tycho Brahe's supernova (3C 10) was observed with the Westerbork telescope at 21 cm in 1971 and 1979, and these measurements have been used to determine the radial expansion rate. The average value obtained is 0.256 +- 0.026 arcsec yr-1. Although this seems to be higher than that found optically, the individual radio and optical data points agree well within the errors. The apparent discrepancy is primarily the result of a low expansion speed at the position of the most prominent nebulosity, and this is attributed to deceleration caused by the higher density of material. While the expansion speed only marginally exceeds that predicted by the Sedov solution, the confirmation lent by the optical data suggests a possible real effect. Two plausible explanations are considered: the remnant is not yet fully in the adiabatic phase; or the dynamics are being modified by the evaporation of neutral material behind the shock front. Whether either of these is the correct explanation, it is clear that swept-up material now dominates the dynamics of 3C 10. No significant change in flux density was detected at a level which favours models where particle acceleration/field amplification are occurring over that of simple adiabatic expansion. (author).

1982-01-01

262

Expansion of the supernova remnant 3C 10 (Tycho) and its implications for models of young remnants  

Energy Technology Data Exchange (ETDEWEB)

The remnant of Tycho Brahe's supernova (3C 10) was observed with the Westerbork telescope at 21 cm in 1971 and 1979, and these measurements have been used to determine the radial expansion rate. The average value obtained is 0.256 +- 0.026 arcsec yr/sup -1/. Although this seems to be higher than that found optically, the individual radio and optical data points agree well within the errors. The apparent discrepancy is primarily the result of a low expansion speed at the position of the most prominent nebulosity, and this is attributed to deceleration caused by the higher density of material. While the expansion speed only marginally exceeds that predicted by the Sedov solution, the confirmation lent by the optical data suggests a possible real effect. Two plausible explanations are considered: the remnant is not yet fully in the adiabatic phase; or the dynamics are being modified by the evaporation of neutral material behind the shock front. Whether either of these is the correct explanation, it is clear that swept-up material now dominates the dynamics of 3C 10. No significant change in flux density was detected at a level which favours models where particle acceleration/field amplification are occurring over that of simple adiabatic expansion.

Strom, R.G. (Netherlands Foundation for Radio Astronomy, Dwingeloo); Goss, W.M. (Rijksuniversiteit Groningen (Netherlands). Kapteyn Sterrewacht); Shaver, P.A. (European Southern Observatory, Garching (Germany, F.R.))

1982-08-01

263

Supernova Remnants and the Interstellar Medium of M83: Imaging & Photometry with WFC3 on HST  

CERN Document Server

We present Wide Field Camera 3 images taken with the Hubble Space Telescope within a single field in the southern grand design star-forming galaxy M83. Based on their size, morphology and photometry in continuum-subtracted H$\\alpha$, [\\SII], H$\\beta$, [\\OIII] and [\\OII] filters, we have identified 60 supernova remnant candidates, as well as a handful of young ejecta-dominated candidates. A catalog of these remnants, their sizes and, where possible their H$\\alpha$ fluxes are given. Radiative ages and pre-shock densities are derived from those SNR which have good photometry. The ages lie in the range $2.62 < log(\\tau_{\\rm rad}/{\\rm yr}) < 5.0$, and the pre-shock densities at the blast wave range over $0.56 < n_0/{\\rm cm^{-3}} < 1680$. Two populations of SNR have been discovered. These divide into a nuclear and spiral arm group and an inter-arm population. We infer an arm to inter-arm density contrast of 4. The surface flux in diffuse X-rays is correlated with the inferred pre-shock density, indicati...

Dopita, Michael A; Long, Knox S; Mutchler, Max; Whitmore, Bradley C; Kuntz, Kip D; Balick, Bruce; Bond, Howard E; Calzetti, Daniela; Carollo, Marcella; Disney, Michael; Frogel, Jay A; O'Connell, Robert; Hall, Donald; Holtzman, Jon A; Kimble, Randy A; MacKenty, John; McCarthy, Patrick; Paresce, Francesco; Saha, Abhijit; Silk, Joe; Sirianni, Marco; Trauger, John; Walker, Alistair R; Windhorst, Rogier; Young, Erick

2010-01-01

264

3D simulations of supernova remnants evolution including non-linear particle acceleration  

CERN Document Server

If a sizeable fraction of the energy of supernova remnant shocks is channeled into energetic particles (commonly identified with Galactic cosmic rays), then the morphological evolution of the remnants must be distinctly modified. Evidence of such modifications has been recently obtained with the Chandra and XMM-Newton X-ray satellites. To investigate these effects, we coupled a semi-analytical kinetic model of shock acceleration with a 3D hydrodynamic code (by means of an effective adiabatic index). This enables us to study the time-dependent compression of the region between the forward and reverse shocks due to the back reaction of accelerated particles, concomitantly with the development of the Rayleigh-Taylor hydrodynamic instability at the contact discontinuity. Density profiles depend critically on the injection level eta of particles: for eta up to about 10^-4 modifications are weak and progressive, for eta of the order of 10^-3 modifications are strong and immediate. Nevertheless, the extension of the...

Ferrand, Gilles; Ballet, Jean; Teyssier, Romain; Fraschetti, Federico

2009-01-01

265

Discovery of optical emission from the supernova remnant G 32.8-0.1 (Kes 78)  

CERN Multimedia

Deep optical CCD images of the supernova remnant G 32.8-0.1 were obtained where filamentary and diffuse emission was discovered. The images were acquired in the emission lines of Halpha+[N II] and [S II]. Filamentary and diffuse structures are detected in most areas of the remnant, while no significant [O III] emission is present. The flux-calibrated images suggest that the optical emission originates from shock-heated gas since the [S II]/Halpha ratio is greater than 1.2. The Spitzer images at 8 micron and 24 micron show a few filamentary structures to be correlated with the optical filaments, while the radio emission at 1.4 GHz in the same area is found to be very well correlated with the brightest optical filaments. Furthermore, the results from deep long-slit spectra also support the origin of the emission to be from shock-heated gas ([S II]/Halpha > 1.5). The absence of [O III] emission indicates slow shocks velocities into the interstellar "clouds" (< 100 km/s), while the [S II] 6716/6731 ratio indic...

Boumis, P; Alikakos, J; Christopoulou, P E; Mavromatakis, F; Katsiyannis, A C; Goudis, C D

2009-01-01

266

AZIMUTHAL DENSITY VARIATIONS AROUND THE RIM OF TYCHO's SUPERNOVA REMNANT  

Energy Technology Data Exchange (ETDEWEB)

Spitzer images of Tycho's supernova remnant in the mid-infrared reveal limb-brightened emission from the entire periphery of the shell and faint filamentary structures in the interior. As with other young remnants, this emission is produced by dust grains, warmed to {approx}100 K in the post-shock environment by collisions with energetic electrons and ions. The ratio of the 70 to 24 {mu}m fluxes is a diagnostic of the dust temperature, which in turn is a sensitive function of the plasma density. We find significant variations in the 70/24 flux ratio around the periphery of Tycho's forward shock, implying order-of-magnitude variations in density. While some of these are likely localized interactions with dense clumps of the interstellar medium (ISM), we find an overall gradient in the ambient density surrounding Tycho, with densities 3-10 times higher in the northeast than in the southwest. This large density gradient is qualitatively consistent with the variations in the proper motion of the shock observed in radio and X-ray studies. Overall, the mean ISM density around Tycho is quite low ({approx}0.1-0.2 cm{sup -3}), consistent with the lack of thermal X-ray emission observed at the forward shock. We perform two-dimensional hydrodynamic simulations of a Type Ia supernova expanding into a density gradient in the ISM, and find that the overall round shape of the remnant is still easily achievable, even for explosions into significant gradients. However, this leads to an offset of the center of the explosion from the geometric center of the remnant of up to 20%, although lower values of 10% are preferred. The best match with hydrodynamical simulations is achieved if Tycho is located at a large (3-4 kpc) distance in a medium with a mean preshock density of {approx}0.2 cm{sup -3}. Such preshock densities are obtained for highly ({approx}> 50%) porous ISM grains.

Williams, Brian J.; Hewitt, John W.; Petre, Robert [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Borkowski, Kazimierz J.; Alwin Mao, S.; Reynolds, Stephen P.; Blondin, John M. [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Ghavamian, Parviz, E-mail: brian.j.williams@nasa.gov [Department of Physics, Astronomy, and Geosciences, Towson University, Towson, MD 21252 (United States)

2013-06-20

267

AN EXTREME PULSAR TAIL PROTRUDING FROM THE FRYING PAN SUPERNOVA REMNANT  

Energy Technology Data Exchange (ETDEWEB)

The Frying Pan (G315.9-0.0) is a radio supernova remnant with a peculiar linear feature (G315.78-0.23) extending 10' radially outward from the rim of the shell. We present radio imaging and polarization observations obtained from the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array, confirming G315.78-0.23 as a bow-shock pulsar wind nebula (PWN) powered by the young pulsar J1437-5959. This is one of the longest pulsar tails observed in radio and it has a physical extent over 20 pc. We found a bow-shock standoff distance of 0.002 pc, smallest among similar systems, suggesting a large pulsar velocity over 1000 km s{sup -1} and a high Mach number {approx}200. The magnetic field geometry inferred from radio polarimetry shows a good alignment with the tail orientation, which could be a result of high flow speed. There are also hints that the postshock wind has a low magnetization and is dominated by electrons and positrons in energy. This study shows that PWNe can offer a powerful probe of their local environment, particularly for the case of a bow shock where the parent supernova shell is also detected.

Ng, C.-Y.; Bouchard, A. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Bucciantini, N. [NORDITA, Albanova Research Center, 106 91 Stockholm (Sweden); Gaensler, B. M. [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia); Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Chatterjee, S., E-mail: ncy@physics.mcgill.ca [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States)

2012-02-10

268

An Extreme Pulsar Tail Protruding from the Frying Pan Supernova Remnant  

Science.gov (United States)

The Frying Pan (G315.9-0.0) is a radio supernova remnant with a peculiar linear feature (G315.78-0.23) extending 10' radially outward from the rim of the shell. We present radio imaging and polarization observations obtained from the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array, confirming G315.78-0.23 as a bow-shock pulsar wind nebula (PWN) powered by the young pulsar J1437-5959. This is one of the longest pulsar tails observed in radio and it has a physical extent over 20 pc. We found a bow-shock standoff distance of 0.002 pc, smallest among similar systems, suggesting a large pulsar velocity over 1000 km s-1 and a high Mach number ~200. The magnetic field geometry inferred from radio polarimetry shows a good alignment with the tail orientation, which could be a result of high flow speed. There are also hints that the postshock wind has a low magnetization and is dominated by electrons and positrons in energy. This study shows that PWNe can offer a powerful probe of their local environment, particularly for the case of a bow shock where the parent supernova shell is also detected.

Ng, C.-Y.; Bucciantini, N.; Gaensler, B. M.; Camilo, F.; Chatterjee, S.; Bouchard, A.

2012-02-01

269

AN EXTREME PULSAR TAIL PROTRUDING FROM THE FRYING PAN SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

The Frying Pan (G315.9–0.0) is a radio supernova remnant with a peculiar linear feature (G315.78–0.23) extending 10' radially outward from the rim of the shell. We present radio imaging and polarization observations obtained from the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array, confirming G315.78–0.23 as a bow-shock pulsar wind nebula (PWN) powered by the young pulsar J1437–5959. This is one of the longest pulsar tails observed in radio and it has a physical extent over 20 pc. We found a bow-shock standoff distance of 0.002 pc, smallest among similar systems, suggesting a large pulsar velocity over 1000 km s–1 and a high Mach number ?200. The magnetic field geometry inferred from radio polarimetry shows a good alignment with the tail orientation, which could be a result of high flow speed. There are also hints that the postshock wind has a low magnetization and is dominated by electrons and positrons in energy. This study shows that PWNe can offer a powerful probe of their local environment, particularly for the case of a bow shock where the parent supernova shell is also detected.

2012-02-10

270

The contribution of supernova remnants to the galactic cosmic ray spectrum  

CERN Multimedia

The supernova paradigm for the origin of galactic cosmic rays has been deeply affected by the development of the non-linear theory of particle acceleration at shock waves. Here we discuss the implications of applying such theory to the calculation of the spectrum of cosmic rays at Earth as accelerated in supernova remnants and propagating in the Galaxy. The spectrum is calculated taking into account the dynamical reaction of the accelerated particles on the shock, the generation of magnetic turbulence which enhances the scattering near the shock, and the dynamical reaction of the amplified field on the plasma. Most important, the spectrum of cosmic rays at Earth is calculated taking into account the flux of particles escaping from upstream during the Sedov-Taylor phase and the adiabatically decompressed particles confined in the expanding shell and escaping at later times. We show how the spectrum obtained in this way is well described by a power law in momentum with spectral index close to -4, despite the co...

Caprioli, D; Blasi, P

2009-01-01

271

Asymmetric Circumstellar Matter in Type Ia Supernova Remnants  

Science.gov (United States)

The progenitors of Type Ia supernovae (SNe) are not well understood, but are likely to be of diverse origin, including single- and double-degenerate binary systems. Among single-degenerate progenitors, substantial amounts of circumstellar material (CSM) are expelled prior to the SN explosions by asymptotic giant branch (AGB) companions to the accreting white dwarfs. A subsequent collision of SN ejecta with the dense AGB wind has been detected among several distant SNe such as SN 2002ic, SN 2008J, and more recently PTF11kx. Dense CSM ejected by an AGB companion is present in the remnant of Kepler's SN of 1604, a Type Ia event. Observations of distant SNe hint at strongly asymmetric CSM distributions. A recent study of the CSM in Kepler's SNR by Burkey et al. indicates a large (factor of 10) density contrast between the dense, disk-like equatorial outflow and the more tenuous AGB wind above the orbital plane. A significant fraction of mature Type Ia SNRs in the Large Magellanic Cloud (LMC) shows the presence of dense Fe-rich ejecta in their interiors that cannot be explained by standard models of Type Ia explosions in a uniform ambient interstellar medium. We explore the hypothesis that these remnants originated in Type Ia explosions with strongly asymmetric CSM distributions such as found in Kepler's SNR. We present results of 2-D hydrodynamical simulations of the interaction of SN ejecta with asymmetric, disk-like AGB winds throughout the whole adiabatic stage of SNR evolution. Dense, asymmetric, and highly-ionized Fe-rich ejecta are indeed present in the simulated remnants, while the blast wave assumes a spherical shape shortly after passage through the ambient CSM. We also present simulated X-ray images and spectra and compare them with X-ray observations of selected remnants in the LMC. These remnants include DEM L238 and L249, recently observed by Suzaku, whose X-ray emission is strongly dominated by dense Fe-rich ejecta in their interiors. We contrast these remnants to more typical mature Type Ia SNRs such as 0534-69.9 and 0548-70.4 whose Suzaku spectra can be satisfactorily modeled with standard (without any CSM) X-ray models for Type Ia SNRs.

Borkowski, Kazimierz J.; Reynolds, S. P.; Blondin, J. M.

2013-01-01

272

Aspherical Supernova Shock Breakout and the Observations of Supernova 2008D  

CERN Document Server

Shock breakout is the earliest, readily-observable emission from a core-collapse supernova explosion. Observing supernova shock breakout may yield information about the nature of the supernova shock prior to exiting the progenitor and, in turn, about the core-collapse supernova mechanism itself. X-ray Outburst 080109, later associated with SN 2008D, is a very well-observed example of shock breakout from a core-collapse supernova. Despite excellent observational coverage and detailed modeling, fundamental information about the shock breakout, such as the radius of breakout and driver of the light curve time scale, is still uncertain. The models constructed for explaining the shock breakout emission from SN 2008D all assume spherical symmetry. We present a study of the observational characteristics of {\\it aspherical} shock breakout from stripped-envelope core-collapse supernovae. We conduct two-dimensional, jet-driven supernova simulations from stripped-envelope progenitors and calculate the resulting shock br...

Couch, Sean M; Wheeler, J Craig; Milosavljevic, Milos

2010-01-01

273

Evolution of Supernova Remnants Expanding out of the Dense Circumstellar Matter into the Rarefied Interstellar Medium  

Science.gov (United States)

We carried out 3D-hydrodynamical calculations for the interaction of expanding supernova ejecta with the dense circumstellar matter (CSM) and the rarefied interstellar medium (ISM) outside. The CSM is composed of stellar-wind matter from the progenitor in its pre-supernova phase, and assumed to be axially symmetric: more matter around the equator than in the polar direction driven by rotation of the progenitor. Because of the high density of the CSM, the ionization state of the shock-heated ejecta quickly becomes equilibrium with the electron temperature. When the blast wave breaks out of the CSM into the rarefied ISM, the shocked ejecta cools rapidly due to adiabatic expansion, and hence an over-ionized/recombining plasma would be left. The ejecta is reheated by the second reverse shock due to the interaction with the ISM. We calculated the emission measure of the supernova remnant (SNR) along the line of sight, and found that the over-ionized plasma appears to be bar-like with wings in the edge-on (equatorial view), while shell-like in the face-on (polar view) geometry with respect to the rotation axis. Hot gas heated by the blast wave exists in the outermost region of the SNR with a nearly complete shell, but the X-rays therefrom are too faint to be observable. Thus, depending on the viewing angle, the SNR of the over-ionized plasma would exhibit a center-filled morphology in X-rays, like W 49 B, a mixed-morphology SNR. The bar-like structure is swept out by the second reverse shock and disappears eventually, and then the SNR becomes shell-like in both the equatorial and polar views in the later phase of evolution.

Shimizu, Takafumi; Masai, Kuniaki; Koyama, Katsuji

2012-04-01

274

Supernova Shock Breakout from a Red Supergiant  

CERN Multimedia

Massive stars undergo a violent death when the supply of nuclear fuel in their cores is exhausted, resulting in a catastrophic `core-collapse' supernova. Such events are usually detected long after the star has exploded. Here we report the first detection of the radiative precursor from a supernova shock before it has reached the surface of a star followed by the initial expansion of the star at the beginning of the explosion. Theoretical models of the ultraviolet light curve show that the progenitor was a red supergiant, as expected for this type of supernova. These observations provide a promising and novel way to probe the physics of core-collapse supernovae and the internal structures of their progenitors.

Schawinski, Kevin; Wolf, Christian; Podsiadlowski, Philipp; Sullivan, Mark; Steenbrugge, Katrien C; Bell, Tony; Roeser, Hermann-Josef; Walker, Emma; Astier, Pierre; Balam, Dave; Balland, Christophe; Basa, Stephane; Carlberg, Ray; Conley, Alex; Fouchez, Dominque; Guy, Julien; Hardin, Delphine; Hook, Isobel; Howell, Andy; Pain, Reynald; Perrett, Kathy; Pritchet, Chris; Regnault, Nicolas; Yi, Sukyoung K

2008-01-01

275

New upper limit on intensity of forbidden Fe XIV 5303 in Tycho's supernova remnant  

Energy Technology Data Exchange (ETDEWEB)

Analysis of a CCD image of the remnant of Tycho's supernova made in the forbidden coronal green line fails to reveal emission at a limit of 3.1 x 10 to the -8th ergs/sq cm s sr at the location of the reverse shock into the ejecta. The nondetection may imply that the reverse shock has not yet reached Fe-enriched ejecta or that the known clumpiness of the ejecta prevents production of observable amounts of Fe(+13). 19 refs.

Teske, R.G. (Michigan Univ., Ann Arbor (USA))

1990-10-01

276

Fermi LAT gamma-ray observations of the supernova remnant HB21  

CERN Document Server

We present the analysis of Fermi Large Area Telescope (LAT) \\g-ray observations of HB 21, a mixed-morphology supernova remnant. Such supernova remnants are characterized by an interior thermal X-ray plasma, surrounded by a wider nonthermal shell emitting at radio frequencies. HB 21 has a large angular size, making it a good candidate for detailed morphological and spectral studies with the LAT. The radio extension is $2^\\circ\\times1^\\circ$, compared to the LAT 68% containment angle of $\\sim1^\\circ$ at 1 GeV. To understand the origin of \\g-ray emission, we compare LAT observations with other wavelengths that trace non-thermal radio synchrotron, nearby molecular clouds, shocked molecular clumps, and the central X-ray plasma. Finally, we model possible hadronic and leptonic emission mechanisms. We conclude that \\g-rays from HB 21 are likely the result of electron bremsstrahlung or proton-proton collisions with dense material due to interaction with the nearby clouds.

Pivato, G; Tibaldo, L

2013-01-01

277

Radioactive Scandium in the Youngest Galactic Supernova Remnant G1.9+0.3  

CERN Document Server

We report the discovery of thermal X-ray emission from the youngest Galactic supernova remnant (SNR) G1.9+0.3, from a 237-ks Chandra observation. We detect strong K-shell lines of Si, S, Ar, Ca, and Fe. In addition, we detect a 4.1 keV line with 99.971% confidence which we attribute to 44Sc, produced by electron capture from 44Ti. Combining the data with our earlier Chandra observation allows us to detect the line in two regions independently. For a remnant age of 100 yr, our measured total line strength indicates synthesis of $(1 - 7) \\times 10^{-5}$ solar masses of 44Ti, in the range predicted for both Type Ia and core-collapse (CC) supernovae, but somewhat smaller than the $2 \\times 10^{-4}$ solar masses reported for Cas A. The line spectrum indicates supersolar abundances. The Fe emission has a width of about 26,000 km/s, consistent with an age of about 100 yr and with the inferred mean shock velocity of 14,000 km/s deduced assuming a distance of 8.5 kpc. Most thermal emission comes from regions of lower ...

Borkowski, Kazimierz J; Green, David A; Hwang, Una; Petre, Robert; Krishnamurthy, Kalyani; Willett, Rebecca

2010-01-01

278

The NuSTAR Program for Supernova Remnants  

Science.gov (United States)

The Nuclear Spectroscopic Telescope Array (NuSTAR), successfully launched in June 2012, is the first telescope to bring the the hard X-ray (3 to 79 keV) sky into focus. One of NuSTAR's prime science goals is to study the morphology of the previously unresolved hard X-ray emission from supernova remnants (SNRs). Spatial and spectral characterization of the hard X-ray synchrotron emission is essential to understanding the physics of particle acceleration in SNR and has implications for origin of galactic cosmic rays. Young (NuSTAR plans for observing SNRs as well as early results from SNRs observed in the first six months since launch, including preliminary results for Cassiopeia A. Discussions of Pulsar Wind Nebulae (PWNe) and G21.5-0.9 are presented in a companion posters by K. Madsen and M. Nynka, respectively.

Grefenstette, Brian; An, H.; Boggs, S. E.; Christensen, F.; Craig, W. W.; Freyer, C.; Hailey, C. J.; Harrison, F.; Humensky, B.; Jakobsen, S.; Kaspi, V.; Kitaguchi, T.; Lopez, L. A.; Madsen, K.; Miyasaka, H.; Mori, K.; Nynka, M.; Pivovaroff, M.; Reynolds, S. P.; Stern, D.; Westergaard, N. J.; Wik, D. R.; Zhang, W.; Zoglauer, A.; NuSTAR Team

2013-01-01

279

Gamma Rays from the Tycho Supernova Remnant: Leptonic or Hadronic?  

CERN Document Server

Recent Fermi and VERITAS observations of the prototypical Type Ia supernova remnant (SNR) Tycho have discovered gamma-rays with energies E in the range from ~0.4 GeV to 10 TeV. Crucial for the theory of Galactic cosmic-ray origin is whether the gamma-rays from SNRs are produced by accelerated hadrons (protons and ions), or by relativistic electrons. Here we show that the broadband radiation spectrum of Tycho can be explained within the framework of a two-zone leptonic model, which is likely to apply to every SNR. A model with hadrons can also fit the radiation spectrum. The hadronic origin of gamma-rays can be confirmed by Fermi spectral measurements of Tycho and other SNRs at energies below ~300 MeV.

Atoyan, Armen

2011-01-01

280

Evolution of Tycho's supernova remnant  

Energy Technology Data Exchange (ETDEWEB)

The evolution of Tycho's supernova remnant has been modeled with a numerical calculation based on a similarity solution developed by Chevalier in 1982. The new model has one important addition: a shell of matter, presumably a presupernova planetary nebula, is needed around the exploding white dwarf in order to reproduce some features in the observed morphology of the SNR. In particular, a very thin ''rim'' surrounding the main shell of the SNR cannot be reproduced without the planetary nebula. The evolution has been followed from a time of 10/sup 7/ s to the present epoch (1.3 x 10/sup 10/ s). The results include predictions of the radial distribution of relative brightness in both X-ray and radio wavelengths.

Dickel, J.R.; Jones, E.M.

1985-01-15

 
 
 
 
281

Galactic Gamma-Ray Background Radiation from Supernova Remnants  

CERN Document Server

The contribution of the Source Cosmic Rays (SCRs), confined in Supernova Remnants, to the diffuse high energy \\gr emission above 1 GeV from the Galactic disk is studied. \\grs produced by the SCRs have a much harder spectrum compared with those generated by the Galactic Cosmic Rays which occupy a much larger residence volume uniformly. SCRs contribute less than 10% at GeV energies and become dominant at \\gr energies above 100 GeV. The contributions from $\\pi^0$-decay and Inverse Compton \\grs have comparable magnitude and spectral shape, whereas the Bremsstrahlung component is negligible. At TeV energies the contribution from SCRs increases the expected diffuse \\gr flux almost by an order of magnitude. It is shown that for the inner Galaxy the discrepancy between the observed diffuse intensity and previous model predictions at energies above a few GeV can be attributed to the SCR contribution.

Berezhko, E G; Berezhko, Evgeny G.; Völk, Heinrich J.

2000-01-01

282

Nonstationary phenomena in the radiation of young supernova remnants  

International Nuclear Information System (INIS)

The time variation of the radio emission from the supernova remnants Cassiopeia A, The Crab Nebula and Tycho Brahe (SN 1572) is investigated. There is a frequency dependence on the rate of decrease in the flux density of Cassiopeia A for the period 1957 to 1984. The (positive) spectral index has a secular decrease and also, for frequencies above 320 MHz, slight oscillations with a six-year period. The radio emission from the Crab Nebula was constant from 1953 to 1975 but has since decrease accompanied by a change in spectral index. The average decrease of the flux density of SN 1572 from 1963 to 1983 was 0.52% per year, close to the value predicted for adiabatic expansion.

283

4C 21. 53: a possible supernova remnant in Vulpecula  

Energy Technology Data Exchange (ETDEWEB)

A compact radio source which exhibits strong interplanetary scintillation lies close to the extended source 4C 21.53 in the galactic plane. The compact source is found to have an angular size of 0.27 arcsec and a flux density of 15 Jy at 81.5 MHz. Synthesis observations at 2.7 GHz of 4C 21.53 reveal it to be 1 arcmin in extent and coincident with the scintillating source to within the limits of error. This paper provides support for the claim that 4C 21.53 may be a Crab-like supernova remnant, although an upper limit of 2 Jy may be set on pulsed emission in the period range 10-200 ms at 81.5 MHz.

Purvis, A. (Mullard Radio Astronomy Observatory, Cambridge (UK). Cavendish Lab.)

1983-02-01

284

Multiwavelength observations of the supernova remnant G349.7+02 interacting with a molecular cloud  

CERN Document Server

We present molecular-line observations at millimetre, centimetre and infrared wavelengths of the region containing OH(1720 MHz) masers in the supernova remnant (SNR) G349.7+0.2. Several molecular transitions were observed between 1.6 and 3 mm to constrain the physical parameters of the molecular cloud interacting with the SNR and to investigate the effects of the SNR shock on the gas chemistry. The observed molecular-line profiles imply the presence of shocked gas with a density around 10^5 cm^{-3} and temperature around 30 K. Our measurements indicate that the abundances of molecular species such as CS, HCN and H2CO are unaffected by the shocks, while HCO+, SO and SiO could be enhanced. We detected shock-excited near-infrared H2 emission towards the centre of the SNR, revealing highly clumped molecular gas. Furthermore, we detected OH absorption at 1665 and 1667 MHz which shows a good correlation with the shocked H2 emission and the masers. We also found maser emission at 1665 MHz near the OH(1720 MHz) maser...

Lazendic, J S; Whiteoak, J B; Burton, M G; Green, A J

2004-01-01

285

Effect of a circumstellar medium on the X-ray emission of young remnants of Type II supernovae  

Energy Technology Data Exchange (ETDEWEB)

Many Type II supernovae explode in dense circumstellar media (CSM). We have investigated the subsequent dynamical evolution and non-equilibrium X-ray emission of the supernova remnant (SNR), using a spherically symmetric hydrodynamic code. The interaction of the supernova ejecta with the dense CSM leads to strong X-ray emission. An extraordinarily high X-ray luminosity of an SNR in NGC 4449 may be interpreted in terms of such an interaction. The interaction leads also to hardening of the X-ray spectrum, if electrons are not heated substantially at the collisionless shock front. After the blast shock breaks out of the CSM into the rarefied ambient medium, the SNR undergoes nearly unimpeded expansion, and the X-ray emission declines drastically. At this stage, the recombination exceeds the ionization, and the X-ray spectrum is characterized by strong recombination lines and continua. However, such spectra have not been observed in young SNRs. The CSM of those supernovae may be considerably less dense or more extended than the CSM of Type II-L supernovae such as SN 1979C and SN 1980K. Alternatively, the CSM of Type II supernovae may be highly inhomogeneous or asymmetric.

Itoh, Hiroshi; Masai, Kuniaki

1989-02-15

286

The effect of a circumstellar medium on the X-ray emission of young remnants of Type II supernovae  

International Nuclear Information System (INIS)

Many Type II supernovae explode in dense circumstellar media (CSM). We have investigated the subsequent dynamical evolution and non-equilibrium X-ray emission of the supernova remnant (SNR), using a spherically symmetric hydrodynamic code. The interaction of the supernova ejecta with the dense CSM leads to strong X-ray emission. An extraordinarily high X-ray luminosity of an SNR in NGC 4449 may be interpreted in terms of such an interaction. The interaction leads also to hardening of the X-ray spectrum, if electrons are not heated substantially at the collisionless shock front. After the blast shock breaks out of the CSM into the rarefied ambient medium, the SNR undergoes nearly unimpeded expansion, and the X-ray emission declines drastically. At this stage, the recombination exceeds the ionization, and the X-ray spectrum is characterized by strong recombination lines and continua. However, such spectra have not been observed in young SNRs. The CSM of those supernovae may be considerably less dense or more extended than the CSM of Type II-L supernovae such as SN 1979C and SN 1980K. Alternatively, the CSM of Type II supernovae may be highly inhomogeneous or asymmetric. (author).

1989-01-01

287

FERMI-LAT DISCOVERY OF GeV GAMMA-RAY EMISSION FROM THE YOUNG SUPERNOVA REMNANT CASSIOPEIA A  

International Nuclear Information System (INIS)

[en] We report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant (SNR) with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. These observations reveal a source with no discernible spatial extension detected at a significance level of 12.2? above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation-Cassiopeia A (Cas A). The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W CR ? (1-4) x 1049 erg thanks to the well-known density in the remnant assuming that the observed gamma ray originates in the SNR shell(s). The magnetic field in the radio-emitting plasma can be robustly constrained as B ? 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.

2010-02-10

288

Fermi-LAT Discovery of GeV Gamma-ray Emission from the Young Supernova Remnant Cassiopeia A  

Energy Technology Data Exchange (ETDEWEB)

We report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. These observations reveal a source with no discernible spatial extension detected at a significance level of 12.2{sigma} above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation - Cassiopeia A. The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W{sub CR} {approx_equal} (1-4) x 10{sup 49} erg thanks to the well-known density in the remnant assuming that the observed gamma-ray originates in the SNR shell(s). The magnetic field in the radio-emitting plasma can be robustly constrained as B {ge} 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.

Abdo, A.A.

2011-08-19

289

Structural changes in Cas A, Tycho and other young supernova remnants  

International Nuclear Information System (INIS)

[en] Structural changes have been found and investigated in a handful of young supernova remnants (SNR). The author considers young shell remnants of which the best studied is Cas A. It is, like the Crab nebula, undergoing an overall radial expansion, although other forms of motion have also been observed. Simple expansion has been found in Tycho (3C10) and the remnant of SN 1006. Optical measurements of the remnant of Kepler's supernova (SN 1604), however, have failed to show motion of the magnitude expected from this relatively young SNR. (Auth.)

1982-09-02

290

The Mipsgal View of Supernova Remnants in the Galactic Plane  

CERN Document Server

We report the detection of Galactic supernova remnants (SNRs) in the mid-infrared (at 24 and 70 {\\mu}m), in the coordinate ranges 10 < l < 65 deg and 285 < l < 350 deg, |b| < 1 deg, using the Multiband Imaging Photometer (MIPS) aboard the Spitzer Space Telescope. We search for infrared counterparts to SNRs in Green's catalog and identify 39 out of 121, i.e., a detection rate of about 32%. Such a relatively low detection fraction is mainly due to confusion with nearby foreground/background sources and diffuse emission. The SNRs in our sample show a linear trend in [F8/F24] versus [F70/F24]. We compare their infrared fluxes with their corresponding radio flux at 1.4 GHz and find that most remnants have ratios of 70 {\\mu}m to 1.4 GHz characteristic of SNRs (with the exception of a few which have ratios closer to those of H II regions). Furthermore, we retrieve a slope close to unity when correlating infrared (24 and 70 {\\mu}m) with 1.4 GHz emission. Our survey is more successful in detecting remna...

Goncalves, D Pinheiro; Paladini, R; Martin, P G; Carey, S J

2011-01-01

291

Infrared Supernova Remnants in the Spitzer GLIMPSE Field  

CERN Multimedia

We have searched for infrared emission of supernova remnants (SNRs) included in the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) field. At the positions of 100 known SNRs, we made 3.6, 4.5, 5.8, and 8.0 um band images covering the radio continuum emitting area of each remnant. The in-depth examinations of four band images based on the radio continuum images of SNRs result in the identification of sixteen infrared SNRs in the GLIMPSE field. Eight SNRs show distinct infrared emissions in nearly all the four bands, and the other eight SNRs are visible in more than one band. We present four band images for all identified SNRs, and RGB-color images for the first eight SNRs. These images are the first high resolution (<2") images with comparative resolution of radio continuum for SNRs detected in the mid-infrared region. The images show typically show filamentary emission along the radio enhanced SNR boundaries. Most SNRs are well identified in the 4.5 and 5.8 um bands. We give a br...

Lee, H G

2005-01-01

292

DISCOVERY OF NEW INTERACTING SUPERNOVA REMNANTS IN THE INNER GALAXY  

International Nuclear Information System (INIS)

OH(1720 MHz) masers are excellent signposts of interaction between supernova remnants (SNRs) and molecular clouds. Using the Green Bank Telescope and Very Large Array we have surveyed 75 SNRs and six candidates for masers. Four SNRs are detected with OH masers: G5.4-1.2, G5.7-0.0, G8.7-0.1, and G9.7-0.0. Two SNRs, G5.7-0.0 and G8.7-0.1, have TeV ?-ray counterparts which may indicate a local cosmic ray enhancement. It has been noted that maser-emitting (ME) SNRs are preferentially distributed in the molecular ring and nuclear disk. We use the present and existing surveys to demonstrate that masers are strongly confined to within |l| ? 50 deg. at a rate of 15% of the total SNR population. All new detections are within 10 deg. Galactic longitude emphasizing this trend. Additionally, a substantial number of SNR masers have peak fluxes at or below the detection threshold of existing surveys. This calls into question whether maser surveys of Galactic SNRs can be considered complete and how many ME remnants remain to be detected in the Galaxy.

2009-03-20

293

Rejuvenating the shells of supernova remnants by pulsar winds  

CERN Document Server

We reconsider the rejuvenation mechanism as proposed by Shull, Fesen, & Saken (1989). These authors suggest that an active pulsar can catch up with, and rejuvenate the shell of the associated supernova remnant. The morphology of the SNRs G5.4-1.2 and CTB80 seem to confirm this rejuvenation mechanism. The spindown energy is deposited by the pulsar as a relativistic pulsar wind, and has a sufficient power to explain the observed radio emission observed in these remnants. Shull et al. (1989) did {\\it not} explain the observed lengthscales of the rejuvenated parts of the SNR shell. therefore one needs to consider the diffusive transport of the injected electrons by the pulsar wind. We propose to apply a diffusion mechanism as introduced by Jokipii (1987), which makes a distinction between diffusion along the magnetic field lines and perpendicular to the magnetic field lines, parameterised by the gyro factor $\\eta$. We show that one has to assume a high value for the gyro factor, $\\eta\\simeq 10^3-10^4$, i.e. d...

Van der Swaluw, E; Gallant, Y A; Swaluw, Eric van der; Achterberg, Abraham; Gallant, Yves A.

2001-01-01

294

A Possible Supernova Remnant high above the Galactic Disk  

CERN Multimedia

We present the analysis of three Suzaku observations of a bright arc in the ROSAT All-Sky Survey 1/4 keV maps at $l \\approx 247\\degr$, $b \\approx -64\\degr$. In particular, we have tested the hypothesis that the arc is the edge of a bubble blown by an extraplanar supernova. One pointing direction is near the brightest part of the arc, one is toward the interior of the hypothesized bubble, and one is toward the bubble exterior. We fit spectral models generated from 1-D hydrodynamical simulations of extraplanar supernova remnants (SNRs) to the spectra. The spectra and the size of the arc ($\\mathrm{radius} \\approx 5\\degr$) are reasonably well explained by a model in which the arc is the bright edge of a $\\sim$100,000-yr old SNR located $\\sim$1--2 kpc above the disk. The agreement between the model and the observations can be improved if the metallicity of the X-ray--emitting gas is $\\sim$1/3 solar, which is plausible, as the dust which sequesters some metals is unlikely to have been destroyed in the lifetime of t...

Henley, David B

2009-01-01

295

Supernova remnants with magnetars: clues to magnetar formation  

CERN Multimedia

I discuss the lack of observational evidence that magnetars are formed as rapidly rotating neutron stars. Supernova remnants containing magnetars do not show the excess of kinetic energy expected for such a formation scenario, nor is there any evidence for a relic pulsar wind nebula. However, it could be that magnetars are formed with somewhat slower rotation periods, or that not all excess rotational energy was used to boost the explosion energy, for example as a result of gravitational radiation. Another observational tests for the rapid initial period hypothesis is to look for statistical evidence that about 1% of the observed supernovae have an additional 1E40-1E44 erg/s excess energy during the first year, caused by the spin down luminosity of a magnetar. An alternative scenario for the high magnetic fields of magnetars is the fossil field hypothesis, in which the magnetic field is inherited from the progenitor star. Direct observational tests for this hypothesis are harder to formulate, unless the neutr...

Vink, Jacco

2007-01-01

296

Mechanism for spectral break in cosmic ray proton spectrum of supernova remnant W44.  

UK PubMed Central (United Kingdom)

Recent observations of supernova remnant W44 by the Fermi spacecraft observatory support the idea that the bulk of galactic cosmic rays is accelerated in such remnants by a Fermi mechanism, also known as diffusive shock acceleration. However, the W44 expands into weakly ionized dense gas, and so a significant revision of the mechanism is required. Here, we provide the necessary modifications and demonstrate that strong ion-neutral collisions in the remnant surrounding lead to the steepening of the energy spectrum of accelerated particles by exactly one power. The spectral break is caused by Alfven wave evanescence leading to the fractional particle losses. The gamma-ray spectrum generated in collisions of the accelerated protons with the ambient gas is calculated and successfully fitted to the Fermi Observatory data. The parent proton spectrum is best represented by a classical test particle power law ?E(-2), steepening to E(-3) at E(br)?7?GeV due to deteriorated particle confinement.

Malkov MA; Diamond PH; Sagdeev RZ

2011-01-01

297

Mechanism for spectral break in cosmic ray proton spectrum of supernova remnant W44.  

Science.gov (United States)

Recent observations of supernova remnant W44 by the Fermi spacecraft observatory support the idea that the bulk of galactic cosmic rays is accelerated in such remnants by a Fermi mechanism, also known as diffusive shock acceleration. However, the W44 expands into weakly ionized dense gas, and so a significant revision of the mechanism is required. Here, we provide the necessary modifications and demonstrate that strong ion-neutral collisions in the remnant surrounding lead to the steepening of the energy spectrum of accelerated particles by exactly one power. The spectral break is caused by Alfven wave evanescence leading to the fractional particle losses. The gamma-ray spectrum generated in collisions of the accelerated protons with the ambient gas is calculated and successfully fitted to the Fermi Observatory data. The parent proton spectrum is best represented by a classical test particle power law ?E(-2), steepening to E(-3) at E(br)?7?GeV due to deteriorated particle confinement. PMID:21326226

Malkov, M A; Diamond, P H; Sagdeev, R Z

2011-02-15

298

Evolution of the Radio Remnant of Supernova 1987A: Morphological Changes from Day 7000  

CERN Multimedia

We present radio imaging observations of supernova remnant 1987A at 9 GHz, taken with the Australia Telescope Compact Array over 21 years from 1992 to 2013. By employing a Fourier modeling technique to fit the visibility data, we show that the remnant structure has evolved significantly since day 7000 (mid-2006): the emission latitude has gradually decreased, such that the overall geometry has become more similar to a ring structure. Around the same time, we find a decreasing trend in the east-west asymmetry of the surface emissivity. These results could reflect the increasing interaction of the forward shock with material around the circumstellar ring, and the relative weakening of the interaction with the lower-density material at higher latitudes. The morphological evolution caused an apparent break in the remnant expansion measured with a torus model, from a velocity of 4600+150-200 km/s between day 4000 and 7000 to 2400+100-200 km/s after day 7000. However, we emphasize that there is no conclusive eviden...

Ng, C -Y; Potter, T M; Staveley-Smith, L; Gaensler, B M; Manchester, R N; Tzioumis, A K

2013-01-01

299

A POSSIBLE SUPERNOVA REMNANT HIGH ABOVE THE GALACTIC DISK  

International Nuclear Information System (INIS)

We present the analysis of three Suzaku observations of a bright arc in the ROSAT All-Sky Survey 1/4 keV maps at l ? 247 deg., b ? -64 deg. In particular, we have tested the hypothesis that the arc is the edge of a bubble blown by an extraplanar supernova. One pointing direction is near the brightest part of the arc, one is toward the interior of the hypothesized bubble, and one is toward the bubble exterior. We fit spectral models generated from one-dimensional hydrodynamical simulations of extraplanar supernova remnants (SNRs) to the spectra. The spectra and the size of the arc (radius ? 5 deg.) are reasonably well explained by a model in which the arc is the bright edge of a ?100,000 yr old SNR located ?1-2 kpc above the disk. The agreement between the model and the observations can be improved if the metallicity of the X-ray-emitting gas is ?1/3 solar, which is plausible, as the dust which sequesters some metals is unlikely to have been destroyed in the lifetime of the SNR. The width of the arc is larger than that predicted by our SNR model; this discrepancy is also seen with the Vela SNR, and may be due to the one-dimensional nature of our simulations. If the arc is indeed the edge of an extraplanar SNR, this work supports the idea that extraplanar supernovae contribute to the heating of the ?million degree gas in the halo.

2009-08-20

300

Observations of the supernova remnants Cas-A and Tycho with the HEGRA stereoscopic IACT system  

UK PubMed Central (United Kingdom)

Recently, young supernova remnants (SNR) from type Ia Supernovae (SNe) have become targets of interestfor TeV gamma-ray astronomy. This prompted the HEGRA collaboration to extensively observe Tycho's SNRin 1997 and 1998 with its stereoscopic IACT system. The HEGRA IACT system was also used to observethe young SNR Cas-A. Although considered to be the result of a SN type Ib, the detected strong nonthermalX-ray emission makes this SNR a promising candidate for TeV gamma-ray emission. Given the 0:1ffispatialresolution of the system, both sources are still nearly pointlike. Therefore, the data samples yield an emissionsensitivity close to a few percent of the Crab flux. The Cas-A observations reveal evidence for a TeV signal.1 IntroductionTycho's SNR is currently considered to be one of the best 'laboratories' to see Cosmic Ray acceleration inSupernova shock waves by the detection of nucleonic induced TeV gamma-rays (V olk, 1997). It is a shell-typeremnant of a SN explosion ...

G. P Uhlhofer; H. V Olk; C. A. Wiedner

 
 
 
 
301

Observations of the supernova remnants Cas-A and Tycho with the HEGRA stereoscopic IACT system  

UK PubMed Central (United Kingdom)

Recently, young supernova remnants (SNR) from type Ia Supernovae (SNe) have become targets of interestfor TeV gamma-ray astronomy. This prompted the HEGRA collaboration to extensively observe Tycho's SNRin 1997 and 1998 with its stereoscopic IACT system. The HEGRA IACT system was also used to observethe young SNR Cas-A. Although considered to be the result of a SN type Ib, the detected strong nonthermalX-ray emission makes this SNR a promising candidate for TeV gamma-ray emission. Given the spatialresolution of the system, both sources are still nearly pointlike. Therefore, the data samples yield an emissionsensitivity close to a few percent of the Crab flux. The Cas-A observations reveal evidence for a TeV signal.1 IntroductionTycho's SNR is currently considered to be one of the best 'laboratories' to see Cosmic Ray acceleration inSupernova shock waves by the detection of nucleonic induced TeV gamma-rays (V olk, 1997). It is a shell-typeremnant of a SN explosion of...

G. P Uhlhofer; C. A. Wiedner; For The Hegra Collaboration

302

EXPECTED GAMMA-RAY EMISSION OF SUPERNOVA REMNANT SN 1987A  

International Nuclear Information System (INIS)

A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) is employed to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5-100 yr. It is shown that an efficient production of nuclear CRs leads to a strong modification of the outer SNR shock and to a large downstream magnetic field Bd ? 20 mG. The shock modification and the strong field are required to yield the steep radio emission spectrum observed, as well as the considerable synchrotron cooling of high-energy electrons which diminishes their X-ray synchrotron flux. These features are also consistent with the existing X-ray observations. The expected ?-ray energy flux at TeV energies at the current epoch is nearly ?? F? ? 4 x 10-13 erg cm2 s-1 under reasonable assumptions about the overall magnetic field topology and the turbulent perturbations of this field. The general nonthermal strength of the source is expected to increase roughly by a factor of two over the next 15-20 years; thereafter, it should decrease with time in a secular form.

2011-05-01

303

Escaping the accelerator: how, when and in what numbers do cosmic rays get out of supernova remnants?  

Science.gov (United States)

The escape of charged particles accelerated by diffusive shock acceleration from supernova remnants is shown to be a more complex process than normally appreciated. Using a box model it is shown that the high-energy end of the spectrum can exhibit spectral breaks even with no formal escape as a result of geometrical dilution and changing time-scales. It is pointed out that the bulk of the cosmic ray particles at lower energies must be produced and released in the late stages of the remnant's evolution, whereas the high-energy particles are produced early on; this may explain recent observations of slight compositional variations with energy. Escape resulting from ion-neutral friction in dense and partially ionized media is discussed briefly and some comments made on the use of the so-called ‘free-escape boundary conditions’. Finally, estimates are made of the total production spectrum integrated over the life of the remnant.

Drury, L. O'c.

2011-08-01

304

Escaping the accelerator; how, when and in what numbers do cosmic rays get out of supernova remnants?  

CERN Document Server

The escape of charged particles accelerated by diffusive shock acceleration from supernova remnants is shown to be a more complex process than normally appreciated. Using a box model it is shown that the high-energy end of the spectrum can exhibit spectral breaks even with no formal escape as a result of geometrical dilution and changing time-scales. It is pointed out that the bulk of the cosmic ray particles at lower energies must be produced and released in the late stages of the remnant's evolution whereas the high energy particles are produced early on; this may explain recent observations of slight compositional variations with energy. Escape resulting from ion-neutral friction in dense and partially ionized media is discussed briefly and some comments made on the use of so-called "free escape boundary conditions". Finally estimates are made of the total production spectrum integrated over the life of the remnant.

Drury, Luke O'C

2010-01-01

305

X-ray observations of the supernova remnant MSH 11-54  

Energy Technology Data Exchange (ETDEWEB)

Soft X-ray observations of the X-ray source H1122--59 in the 0.4--2 keV band made with the low-energy detector 1 of the HEAO A-2 experiment are described. Based on positional coincidence, the source is identified with the supernova remnant MSH 11-54, thus confirming the report of Share et al. (1978). The object is a bright source in the 0.4--2 keV band with an X-ray flux of approx.9 x 10/sup -11/ ergs cm/sup -2/ s/sup -1/ near the Earth. The measured source spectrum implies a plasma temperature of approx.4 x 10/sup 6/ K and X-ray luminosity in the 0.4--2 keV band of approx.10/sup 37/ ergs s/sup -1/ using a distance of 10 kpc for MSH 11-54. The X-ray observations, interpreted in terms of an adiabatic shock wave model, give a shock velocity of approx.560 km s/sup -1/ and a supernova age of approx.2300 yr, in good agreement with the age derived from the radio observations.

Agrawal, P.C.; Riegler, G.R.

1980-04-15

306

A Deep Chandra Observation of Kepler's Supernova Remnant: A Type Ia Event with Circumstellar Interaction  

CERN Document Server

We present initial results of a 750 ks Chandra observation of the remnant of Kepler's supernova of AD 1604. The strength and prominence of iron emission, together with the absence of O-rich ejecta, demonstrate that Kepler resulted from a thermonuclear supernova, even though evidence for circumstellar interaction is also strong. We have analyzed spectra of over 100 small regions, and find that they fall into three classes. (1) The vast majority show Fe L emission between 0.7 and 1 keV and Si and S K alpha emission; we associate these with shocked ejecta. A few of these are found at or beyond the mean blast wave radius. (2) A very few regions show solar O/Fe abundance rations; these we associate with shocked circumstellar medium (CSM). Otherwise O is scarce. (3) A few regions are dominated by continuum, probably synchrotron radiation. Finally, we find no central point source, with a limit about 100 times fainter than the central object in Cas A. The evidence that the blast wave is interacting with CSM may indic...

Reynolds, S P; Hwang, U; Hughes, J P; Badenes, C; Laming, J M; Blondin, J M

2007-01-01

307

Cosmic Ray Acceleration by Supernova Shocks  

CERN Multimedia

We analyse the results of recent measurements of nonthermal emission from individual supernova remnants (SNRs) and their correspondence to the nonlinear kinetic theory of cosmic ray (CR) acceleration in SNRs. It is shown that the theory fits these data in a satisfactory way and provides the strong evidences for the efficient CR production in SNRs accompanied by significant magnetic field amplification. Magnetic field amplification leads to considerable increase of CR maximum energy so that the spectrum of CRs accelerated in SNRs is consistent with the requirements for the formation of Galactic CR spectrum up to the energy ~10^17 eV.

Berezhko, E G

2008-01-01

308

Cosmic-ray-induced ionization in molecular clouds adjacent to supernova remnants  

CERN Document Server

Energetic gamma rays (GeV to TeV photon energy) have been detected toward several supernova remnants (SNR) that are associated with molecular clouds. If the gamma rays are produced mainly by hadronic processes rather than leptonic processes like bremsstrahlung, then the flux of energetic cosmic ray nuclei (>1 GeV) required to produce the gamma rays can be inferred at the site where the particles are accelerated in SNR shocks. It is of great interest to understand the acceleration of the cosmic rays of lower energy (1 GeV, and careful extrapolation of the spectrum to lower energies offers a method to calculate the ionization rate of the molecular cloud.

Schuppan, F; Black, J H; Casanova, S; Mandelartz, M

2012-01-01

309

Determination of Acceleration Mechanism Characteristics Directly and Non-Parametrically from Observations: Application to Supernova Remnants  

CERN Multimedia

We have developed an inversion method for determination of the characteristics of the acceleration mechanism directly and non-parametrically from the observations, in contrast to the usual forward fitting of parametric model variables to observations. In two recent papers (Petrosian & Chen 2010, Chen & Petrosian 2013), we demonstrate the efficacy of this inversion method by its application to acceleration of electrons in solar flares based on stochastic acceleration by turbulence. Here we explore its application for determining the characteristics of shock acceleration in supernova remnants (SNRs) based on the observed nonthermal radiation from SNRs and the spectrum of the cosmic ray electrons observed near the Earth. The spectra in these sources are related by the process of escape of the electrons from SNRs and energy loss during their transport in the galaxy. Thus, these observations allow us to determine spectral characteristics of the momentum and pitch angle diffusion coefficients, which play cr...

Petrosian, Vahé

2013-01-01

310

Radio polarization of the semicircular supernova remnant G109.1 - 1.0  

International Nuclear Information System (INIS)

The first detection of linear polarization of the semicircular supernova remnant G109.1 - 1.0 is reported. The observations were made at 10 GHz with the Nobeyama 45-m telescope. The degree of polarization typically ranges from several to 30 %. The distribution of the projected magnetic field cannot be simply explained as tangential to the shall of the supernova remnant, but is rather consistent with the general galactic magnetic field. (author).

1987-01-01

311

Numerical Code for Fitting Radial Emission Profile of a Shell Supernova Remnant  

CERN Document Server

Expressions for surface brightness distribution and for flux density have been theoretically derived in the case of two simple models of a shell supernova remnant. The models are: a homogenous optically thin emitting shell with constant emissivity and a synchrotron shell source with radial magnetic field. Interactive Data Language (IDL) codes for fitting theoretically derived emission profiles assuming these two models to mean profiles of shell supernova remnants obtained from radio observations have been written.

Arbutina, Bojan

2012-01-01

312

Evidence for quasi-parallel and quasi-perpendicular acceleration in supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

An attempt is made to determine whether or not the structure of supernova remnant shells is dependent on the angle between the line of sight and the Galactic magnetic field and if this structure can be explained either by quasi-parallel or quasi-perpendicular acceleration. The method used to determine the line of sight angles to the magnetic field is described. A model for the emissivity of a supernova remnant is developed. 46 references.

Leckband, J.A.; Spangler, S.R.; Cairns, I.H.

1989-03-01

313

G70.68+1.20: a thermal source, not a supernova remnant  

International Nuclear Information System (INIS)

[en] G70.68+1.20 is a small shell source, approx.20 arcsec in extent, which has recently been proposed as a very young galactic supernova remnant. 5-GHz observations with the 5-km telescope at a resolution of approx. 2x4 arcsec2 (RAxDec) are presented, and discussed together with other radio, optical and IR data. These favour the interpretation that the source is thermal, rather than a young supernova remnant. (author)

1986-04-01

314

Simulation of the growth of the 3D Rayleigh-Taylor instability in supernova remnants using an expanding reference frame  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Context. The Rayleigh-Taylor instabilities that are generated by the deceleration of a supernova remnant during the ejecta-dominated phase are known to produce finger-like structures in the matter distribution that modify the geometry of the remnant. The morphology of supernova remnants is also expe...

Fraschetti, F; Teyssier, R; Ballet, J; Decourchelle, A

315

Development of an x-ray imaging proportional counter and an analysis of Tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] A soft X-ray imaging proportional counter was developed for use in X-ray astronomy. The detector, a drift multiwire proportional counter, determines the position of the site of X-ray absorption in the detector in two orthogonal directions using the center-of-gravity centroid determination technique. Spatial resolutions of 0.2 millimeters full width at half maximum and 0.5 millimeters full width at half maximum have been obtained at X-ray energies of 0.94 and 0.28 kiloelectron volts, respectively. Energy resolutions of 65 percent full width at half maximum and 110 percent full width at half maximum have been obtained at these energies. The detector and processing electronics were integrated into a rocket-borne X-ray telescope payload capable of providing angular resolutions of 1.0 arcminutes full width at half maximum and 1.3 arcminutes full width at half maximum at X-ray energies of 0.94 and 0.28 kiloelectron volts, respectively. X-ray imaging observations of Tycho's supernova remnant were obtained with the Einstein Observatory imaging proportional counter. The remnant appears as an incomplete shell of radius 3.5 parsecs in the adiabatic phase of evolution. The X-ray and radio shells are spatially coincident, although uncorrelated in intensity. The luminosity at a distance of 3 kiloparsecs is (5.3 +- 1.3) x 1036 ergs per second. The current shock velocity is 3400 +- 140 kilometers per second. An initial blast energy is found of 2.5 x 1051 ergs and an average ambient density is found in the vicinity of Tycho of approximately 3 atoms per cubic centimeter. The mass swept up by the expanding shock wave is estimated at about 20 solar masses. A range of 0.3 to 3 solar masses has been placed on the supernova ejected mass

1982-01-01

316

Proper motions of H? filaments in the supernova remnant RCW 86  

Science.gov (United States)

We present a proper motion study of the eastern shock-region of the supernova remnant RCW 86 (MSH 14-63, G315.4-2.3), based on optical observations carried out with Very Large Telescope/FOcal Reducer and low dispersion Spectrograph 2 in 2007 and 2010. For both the north-eastern and south-eastern regions, we measure an average proper motion of H? filaments of 0.10 ± 0.02 arcsec yr-1, corresponding to 1200 ± 200 km s-1 at 2.5 kpc. There is substantial variation in the derived proper motions, indicating shock velocities ranging from just below 700 km s-1 to above 2200 km s-1. The optical proper motion is lower than the previously measured X-ray proper motion of north-eastern region. The new measurements are consistent with the previously measured proton temperature of 2.3 ± 0.3 keV, assuming no cosmic ray acceleration. However, within the uncertainties, moderately efficient (<27 per cent) shock acceleration is still possible. The combination of optical proper motion and proton temperature rule out the possibility that RCW 86 has a distance less than 1.5 kpc. The similarity of the proper motions in the north-east and south-east is peculiar, given the different densities and X-ray emission properties of the regions. The north-eastern region has lower densities and the X-ray emission is synchrotron dominated, suggesting that the shock velocities should be higher than in the south-eastern, thermal X-ray dominated, region. A possible solution is that the H? emitting filaments are biased towards denser regions, with lower shock velocities. Alternatively, in the north-east the shock velocity may have decreased rapidly during the past 200 yr, and the X-ray synchrotron emission is an afterglow from a period when the shock velocity was higher.

Helder, E. A.; Vink, J.; Bamba, A.; Bleeker, J. A. M.; Burrows, D. N.; Ghavamian, P.; Yamazaki, R.

2013-10-01

317

Supernova Remnants in the Large Magellanic Clouds IX: Multiwavelength Analysis of the Physical Structure of N49  

CERN Document Server

We present a multiwavelength analysis of the supernova remnant N49 in the Large Magellanic Cloud. Using high-resolution Hubble Space Telescope WFPC2 images of H-alpha, [S II] and [O III] emission, we study the morphology of the remnant and calculate the rms electron densities in different regions. We detect an offset of [O III] and H-alpha emission of about 0.5 arcsec, and discuss possible scenarios that could give rise to such high values. The kinematics of the remnant is analyzed by matching individual filaments to the echelle spectra obtained at CTIO. We detect narrow H-alpha emission component which we identify as the diffuse post-shock recombination radiation, and discrete broad emission features that correspond to the shocked gas in filaments. The overall expansion of the remnant is about 250 km/s. The dense clouds are shocked up to line-of-sight velocities of 250 km/s and the less dense gas up to 300 km/s. A few cloudlets have even higher radial velocities, reaching up to 350 km/s. We confirm the prese...

Bilikova, J; Chu, Y -H; Gruendl, R A; Lundgren, B F

2007-01-01

318

The unequivocal evidence of hadron acceleration in Tycho's Supernova Remnant  

CERN Multimedia

We apply the non-linear diffusive shock acceleration theory in order to describe the properties of SN 1572 (G120.1+1.4, hereafter simply Tycho). By analyzing its multi-wavelength spectrum, we show how Tycho's forward shock is accelerating protons up to ~500 TeV, channelling into cosmic rays more than 10% of its kinetic energy. Our model allows us to take into account self-consistently the dynamical reaction of the accelerated particles, the generation of magnetic fields in the shock proximity and the dynamical reaction of the magnetic field as well. We find that the streaming instability induced by cosmic rays is consistent with all the observational evidences indicating a very efficient magnetic field amplification (up to ~300 uG, in particular the radio and X-ray morphology of the remnant. In such a strong magnetic field, the velocity of the scattering centers in the upstream may be enhanced and make accelerated particles feel an effective compression factor lower than 4, in turn leading to an energy spectr...

Morlino, G

2011-01-01

319

Optical observations of supernova remnants; the nebula near ?Cyg  

International Nuclear Information System (INIS)

Detailed optical observations of the nebula near ?Oygz identified with the remnant of the DRU supernova flare have been carried out with the help of the 125-cm reflector. Filter photographs of the object in H?1[N11],[S11], [O111] lines have been obtained; a number of interferometric observations of the nebula and the near H11 region in H? and 6584 A lines with the high-contrast Fabry-Perot etalon and the contact EOC have been carried out. Nebula spectrograms with dispersions 25,60,160A/mm in the range 6000-7000A have been obtained with the help of a diffraction spectrograph. The observations gave the following results: Isub(H?) approximately 10-3 erg cm2 see ster (interstellar absorption has been taken into consideration); Isub(H?):Isub[N11]=2.4; Isub(H?): Isub[S11]=7; I673:I6717=0.7; Vsub(LSR)+9+-3km/sec; the nebula average the H? and 6584 A lines equals 49+-5 and 39+-5 km/sec, respectively; the velocity of the nebula expansion does not exceed 15sub(km)sup(sec). It has been shown that the nebula near ?Cyr cannot be a typical shell created as a result of a supernova flare as in Cygnus, IO443, W28 etc. The nebula parameters are Te=1/2x104K, Ne approximately 102 cm-3, ME approximately 104 cm-6 ps, M approximately 30Mo Usp approximately 25 ps cm -2, if the nebula is the H11 zone. The exciting star has not yet been found. The RF recombination radiation is conditioned by the nebula near ?Cyg and not by a diffuse background

1975-01-01

320

The composite form of the supernova remnant 3C 400.2: two interacting supernova remnants or a single supernova remnant with a blow-out?  

Directory of Open Access Journals (Sweden)

Full Text Available 3C 400.2 es un remanente de supernova galáctico que presenta una morfología que asemeja dos cascarones de diámetros diferentes que se traslapan. Estudiamos la cinemática de ambos cascarones para saber si esta morfología especial es debida al resultado de dos explosiones de supernova diferentes, o bien, a la explosión de una única supernova en un medio que tenga un gradiente de densidad abrupto. Los datos cinemáticos concuerdan mejor con la segunda hipótesis.

Patricia Ambrocio-Cruz; Margarita Rosado; Eduardo de la Fuente

2006-01-01

 
 
 
 
321

Numerical code for fitting radial emission profile of a shell supernova remnant: Application  

Directory of Open Access Journals (Sweden)

Full Text Available We present IDL (Interactive Data Language) codes for fitting a theoretical emission profile of a shell supernova remnant (SNR) to the mean profile of an SNR obtained from radio observations. Two considered theoretical models are: 1) a shell with constant emissivity and 2) a synchrotron shell with radially aligned magnetic field. The codes were applied to several observed supernova remnants. Good results are obtained in five considered cases, which justify the use of our code for remnants that are bright (so that observational errors are not large) and spherically symmetric enough.

Opsenica Slobodan; Arbutina Bojan

2011-01-01

322

Acceleration of cosmic rays by young core-collapse supernova remnants  

Science.gov (United States)

Context. Supernova remnants (SNRs) are thought to be the primary candidates for the sources of Galactic cosmic rays. According to the diffusive shock acceleration theory, SNR shocks produce a power-law spectrum with an index of s = 2, perhaps nonlinearly modified to harder spectra at high energy. Observations of SNRs often indicate particle spectra that are softer than that and show features not expected from classical theory. Known drawbacks of the standard approach are the assumption that SNRs evolve in a uniform environment, and that the reverse shock does not accelerate particles. Relaxing these assumptions increases the complexity of the problem, because one needs reliable hydrodynamical data for the plasma flow as well as good estimates for the magnetic field (MF) at the reverse shock. Aims: We show that these two factors are especially important when modeling young core-collapse SNRs that evolve in a complicated circumstellar medium shaped by the winds of progenitor stars. Methods: We used high-resolution numerical simulations for the hydrodynamical evolution of the SNR. Instead of parametrizations of the MF profiles inside the SNR, we followed the advection of the frozen-in MF inside the SNR, and thus obtained the B-field value at all locations, in particular at the reverse shock. To model cosmic-ray acceleration we solved the cosmic-ray transport equation in test-particle approximation. Results: We find that the complex plasma-flow profiles of core-collapse SNRs significantly modify the particle spectra. Additionally, the reverse shock strongly affects the emission spectra and the surface brightness.

Telezhinsky, I.; Dwarkadas, V. V.; Pohl, M.

2013-04-01

323

Supernova Remnants and Star Formation in the Large Magellanic Cloud  

CERN Multimedia

It has often been suggested that supernova remnants (SNRs) can trigger star formation. To investigate the relationship between SNRs and star formation, we have examined the known sample of 45 SNRs in the Large Magellanic Cloud to search for associated young stellar objects (YSOs) and molecular clouds. We find seven SNRs associated with both YSOs and molecular clouds, three SNRs associated with YSOs but not molecular clouds, and eight SNRs near molecular clouds but not associated with YSOs. Among the 10 SNRs associated with YSOs, the association between the YSOs and SNRs can be either rejected or cannot be convincingly established for eight cases. Only two SNRs have YSOs closely aligned along their rims; however, the time elapsed since the SNR began to interact with the YSOs' natal clouds is much shorter than the contraction timescales of the YSOs, and thus we do not see any evidence of SNR-triggered star formation in the LMC. The 15 SNRs that are near molecular clouds may trigger star formation in the future ...

Desai, K M; Gruendl, R A; Dluger, W; Katz, M; Wong, T; Chen, C -H R; Looney, L W; Hughes, A; Muller, E; Ott, J; Pineda, J L

2010-01-01

324

Discovery of New Interacting Supernova Remnants in the Inner Galaxy  

CERN Document Server

OH(1720 MHz) masers are excellent signposts of interaction between supernova remnants(SNRs) and molecular clouds. Using the GBT and VLA we have surveyed 75 SNRs and six candidates for maser emission. Four new interacting SNRs are detected with OH masers: G5.4-1.2, G5.7-0.0, G8.7-0.1 and G9.7-0.0. The newly detected interacting SNRs G5.7-0.0 and G8.7-0.1 have TeV gamma-ray counterparts which may indicate a local cosmic ray enhancement. It has been noted that maser-emitting SNRs are preferentially distributed in the Molecular Ring and Nuclear Disk. We use the present and existing surveys to demonstrate that masers are strongly confined to within 50 degrees Galactic longitude at a rate of 15 percent of the total SNR population. All new detections are within 10 degrees Galactic longitude emphasizing this trend. Additionally, a substantial number of SNR masers have peak fluxes at or below the detection threshold of existing surveys. This calls into question whether maser surveys of Galactic SNRs can be considered ...

Hewitt, John W

2009-01-01

325

XMM-Newton Observations of Two Candidate Supernova Remnants  

CERN Multimedia

Candidate supernova remnants G23.5+0.1 and G25.5+0.0 were observed by XMM-Newton in the course of a snap-shot survey of plerionic and composite SNRs in the Galactic plane. In the field of G23.5+0.1, we detected an extended source, ~3' in diameter, which we tentatively interpret as a pulsar-wind nebula (PWN) of the middle-aged radio pulsar B1830-08. Our analysis suggests an association between PSR B1830-08 and the surrounding diffuse radio emission. If the radio emission is due to the SNR, then the pulsar must be significantly younger than its characteristic age. Alternatively, the radio emission may come from a relic PWN. In the field of G25.5+0.0, which contains the extended TeV source HESS J1837-069, we detected the recently discovered young high-energy pulsar J1838-0655 embedded in a PWN with extent of 1.3'. We also detected another PWN candidate (AX J1837.3-0652) with an extent of 2' and unabsorbed luminosity L_(2-10 keV) ~ 4 x 10^33 erg/s at d=7 kpc. The third X-ray source, located within the extent of t...

Kargaltsev, O; Pavlov, G G; Misanovic, Z

2011-01-01

326

Non-thermal emission from old supernova remnants  

CERN Document Server

We study the non-thermal emission from old shell-type supernova remnants (SNRs) on the frame of a time-dependent model. In this model, the time-dependent non-thermal spectra of both primary electrons and protons as well as secondary electron/positron ($e^{\\pm}$) pairs can be calculated numerically by taking into account the evolution of the secondary $e^{\\pm}$ pairs produced from proton-proton (p-p) interactions due to the accelerated protons collide with the ambient matter in an SNR. The multi-wavelength photon spectrum for a given SNR can be produced through leptonic processes such as electron/positron synchrotron radiation, bremsstrahlung and inverse Compton scattering as well as hadronic interaction. Our results indicate that the non-thermal emission of the secondary $e^{\\pm}$ pairs is becoming more and more prominent when the SNR ages in the radiative phase because the source of the primary electrons has been cut off and the electron synchrotron energy loss is significant for a radiative SNR, whereas the...

Fang, Jun

2007-01-01

327

Proper Motions of H-alpha filaments in the Supernova Remnant RCW 86  

CERN Multimedia

We present a proper motion study of the eastern shock-region of the supernova remnant RCW 86 (MSH 14-63, G315.4-2.3), based on optical observations carried out with VLT/FORS2 in 2007 and 2010. For both the northeastern and southeastern regions, we measure an average proper motion of H-alpha filaments of 0.10 +/- 0.02 arcsec/yr, corresponding to 1200 +/- 200 km/s at 2.5kpc. There is substantial variation in the derived proper motions, indicating shock velocities ranging from just below 700 km/s to above 2200 km/s. The optical proper motion is lower than the previously measured X-ray proper motion of northeastern region. The new measurements are consistent with the previously measured proton temperature of 2.3 +/- 0.3 keV, assuming no cosmic-ray acceleration. However, within the uncertainties, moderately efficient (< 27 per cent) shock acceleration is still possible. The combination of optical proper motion and proton temperature rule out the possibility that RCW 86 has a distance less than 1.5kpc. The simil...

Helder, E A; Bamba, A; Bleeker, J A M; Burrows, D N; Ghavamian, P; Yamazaki, R

2013-01-01

328

The Origin of Radially Aligned Magnetic Fields in Young Supernova Remnants  

Science.gov (United States)

It has been suggested by radio observations of polarized synchrotron emissions that downstream magnetic fields in some young supernova remnants (SNRs) are oriented radially. We study the magnetic field distribution of turbulent SNRs driven by the Richtmyer-Meshkov instability (RMI)—in other words, the effect of rippled shock—by using three-dimensional magnetohydrodynamics simulations. We find that the induced turbulence has radially biased anisotropic velocity dispersion that leads to a selective amplification of the radial component of the magnetic field. The RMI is induced by the interaction between the shock and upstream density fluctuations. Future high-resolution polarization observations can distinguish the following candidates responsible for the upstream density fluctuations: (1) inhomogeneity caused by the cascade of large-scale turbulence in the interstellar medium, the so-called big power-law in the sky; (2) structures generated by the Drury instability in the cosmic-ray modified shock; and (3) fluctuations induced by the nonlinear feedback of the cosmic-ray streaming instability.

Inoue, Tsuyoshi; Shimoda, Jiro; Ohira, Yutaka; Yamazaki, Ryo

2013-08-01

329

From E. Fermi to Fermi-LAT: watching particle acceleration in supernova remnants  

CERN Multimedia

Supernova remnants (SNRs) have been regarded for many decades as the sources of Galactic cosmic rays (CRs) up to a few PeV. However, only with the advent of Fermi-LAT it has been possible to detect - at least in some SNRs - \\gamma-rays whose origin is unequivocally hadronic, namely due to the decay of neutral pions produced by collisions between relativistic nuclei and the background plasma. When coupled with observations in other bands (from radio to TeV \\gamma-rays), Fermi-LAT data present evidence for CR spectra significantly steeper than the standard prediction of diffusive shock acceleration, forcing us to rethink our theoretical understanding of efficient particle energization at strong shocks. We outline how, by including the effects of CR-triggered magnetic field amplification, it is possible to reconcile non-linear models of diffusive shock acceleration with \\gamma-ray observations, in particular providing a successful application of such a theory to Tycho's SNR. Finally, we show how kinetic simulati...

Caprioli, Damiano

2013-01-01

330

Evolution of Magnetic Fields and Cosmic Ray Acceleration in Supernova Remnants  

CERN Document Server

Observations show that the magnetic field in young supernova remnants (SNRs) is significantly stronger than can be expected from the compression of the circumstellar medium (CSM) by a factor of four expected for strong blast waves. Additionally, the polarization is mainly radial, which is also contrary to expectation from compression of the CSM magnetic field. Cosmic rays (CRs) may help to explain these two observed features. They can increase the compression ratio to factors well over those of regular strong shocks by adding a relativistic plasma component to the pressure, and by draining the shock of energy when CRs escape from the region. The higher compression ratio will also allow for the contact discontinuity, which is subject to the Rayleigh-Taylor (R-T) instability, to reach much further out to the forward shock. This could create a preferred radial polarization of the magnetic field. With an adaptive mesh refinement MHD code (AMRVAC), we simulate the evolution of SNRs with three different configurati...

Schure, K M; Achterberg, A; Keppens, R

2009-01-01

331

DIRECT EVIDENCE FOR HADRONIC COSMIC-RAY ACCELERATION IN THE SUPERNOVA REMNANT IC 443  

International Nuclear Information System (INIS)

The supernova remnant (SNR) IC 443 is an intermediate-age remnant well known for its radio, optical, X-ray, and gamma-ray energy emissions. In this Letter, we study the gamma-ray emission above 100 MeV from IC 443 as obtained by the AGILE satellite. A distinct pattern of diffuse emission in the energy range 100 MeV-3 GeV is detected across the SNR with its prominent maximum (source 'A') localized in the northeastern shell with a flux F=(47±10)x10-8 photons cm-2s-1 above 100 MeV. This location is the site of the strongest shock interaction between the SNR blast wave and the dense circumstellar medium. Source 'A' is not coincident with the TeV source located 0.4 deg. away and associated with a dense molecular cloud complex in the SNR central region. From our observations, and from the lack of detectable diffuse TeV emission from its northeastern rim, we demonstrate that electrons cannot be the main emitters of gamma rays in the range 0.1-10 GeV at the site of the strongest SNR shock. The intensity, spectral characteristics, and location of the most prominent gamma-ray emission together with the absence of cospatial detectable TeV emission are consistent only with a hadronic model of cosmic-ray acceleration in the SNR. A high-density molecular cloud (cloud 'E') provides a remarkable 'target' for nucleonic interactions of accelerated hadrons; our results show enhanced gamma-ray production near the molecular cloud/shocked shell interaction site. IC 443 provides the first unambiguous evidence of cosmic-ray acceleration by SNRs.

2010-02-20

332

AKARI INFRARED OBSERVATIONS OF THE SUPERNOVA REMNANT G292.0+1.8: UNVEILING CIRCUMSTELLAR MEDIUM AND SUPERNOVA EJECTA  

International Nuclear Information System (INIS)

[en] We present the results of AKARI observations of the O-rich supernova remnant (SNR) G292.0+1.8 using six Infrared Camera (IRC) and four Far-Infrared Surveyor bands covering 2.7-26.5 ?m and 50-180 ?m, respectively. The AKARI images show two prominent structures; a bright equatorial ring (ER) structure along the east-west direction and an outer elliptical shell structure surrounding the remnant. The ER structure is clumpy and incomplete with its western end opened. The outer shell is almost complete and slightly squeezed along the north-south direction. The central position of the outer shell is ?1' northwest from the embedded pulsar and coincides with the center of the ER structure. In the northern and southwestern regions, there is also faint emission with a sharp boundary beyond the bright shell structure. The ER and the elliptical shell structures were partly visible in optical and/or X-rays, but they are much more clearly revealed in our AKARI images. There is no evident difference in infrared colors of the two prominent structures, which is consistent with the previous proposition that both structures are of circumstellar origin. However, we have detected faint infrared emission of a considerably high 15/24 ?m ratio associated with the supernova (SN) ejecta in the southeastern and northwestern areas. Our IRC spectra show that the high ratio is at least partly due to the emission lines from Ne ions in the SN ejecta material. In addition, we detect a narrow, elongated feature outside the SNR shell. We derive the physical parameters of the infrared-emitting dust grains in the shocked circumstellar medium (CSM) and compare the result with model calculations of dust destruction by an SN shock. The AKARI results suggest that the progenitor was at the center of the infrared circumstellar shell in the red supergiant stage and that the observed asymmetry in the SN ejecta could be a result of either a dense CSM in the equatorial plane and/or an asymmetric explosion.

2009-11-20

333

Nonthermal emission properties of the northwestern rim of supernova remnant RX J0852-4622  

CERN Document Server

The supernova remnant (SNR) RX J0852-4622 (Vela Jr., G266.6-1.2) is one of the most important SNRs for investigating the acceleration of multi-TeV particles and the origin of Galactic cosmic rays because of its strong synchrotron X-ray and TeV gamma-ray emission, which show a shell-like morphology similar to each other. Using the XMM-Newton archival data consisting of multiple pointing observations of the northwestern rim of the remnant, we investigate the spatial properties of the nonthermal X-ray emission as a function of distance from an outer shock wave. All X-ray spectra are well reproduced by an absorbed power-law model above 2 keV. It is found that the spectra show gradual softening from a photon index 2.56 in the rim region to 2.96 in the interior region. We show that this radial profile can be interpreted as a gradual decrease of the cutoff energy of the electron spectrum due to synchrotron cooling. By using a simple spectral evolution model that includes continuous synchrotron losses, the spectral s...

Kishishita, Tetsuichi; Uchiyama, Yasunobu

2013-01-01

334

THE BROADBAND EMISSION FROM SUPERNOVA REMNANT RX J0852.0-4622  

International Nuclear Information System (INIS)

We study the nonthermal emission from SNR RX J0852.0-4622 based on a self-consistent kinetic method that describes the nonlinear shock acceleration of cosmic rays in supernova remnants (SNRs). In this method, the spectrum of accelerated protons in the SNR can be self-consistently calculated, where a proton's maximum momentum is determined by equating the SNR's age with the acceleration time of the proton. At the same time, the spectrum of accelerated electrons is similar to the proton's spectrum if the electron's momentum is much less than the electron's maximum momentum (pe,max), which is estimated by equating the synchrotron loss time to the acceleration time of the electrons, but the cutoff shapes around pe,max are assumed to be exponential. Using the accelerated particle's spectra, we calculate nonthermal photon spectra for different values of some main model parameters such as the SNR's age, an injection parameter, and a background magnetic field. Moreover, we study possible (hadronic or leptonic) origins of very high energy (VHE) ?-ray emission from SNR RX J0852.0-4622. Our results indicate that a hadronic origin of VHE ?-rays from SNR RX J0852.0-4622 seems to be more reasonable although a leptonic origin cannot be ruled out. We suggest that the observations of Fermi LAT for this remnant will help us find the evidence to determine the main emission mechanism.

2010-09-20

335

Secondary Cosmic Ray Nuclei from Supernova Remnants and Constraints to the Propagation Parameters  

CERN Multimedia

The secondary-to-primary B/C ratio is widely used to study the cosmic ray (CR) propagation processes in the Galaxy. It is usually assumed that secondary nuclei such as Li-Be-B are entirely generated by collisions of heavier CR nuclei with the interstellar medium (ISM). We study the CR propagation under a scenario where secondary nuclei can also be produced or accelerated from galactic sources. We consider the processes of hadronic interactions inside supernova remnants (SNRs) and re-acceleration of background CRs in strong shocks. Thus, we investigate their impact in the propagation parameter determination within present and future data. The spectra of Li-Be-B nuclei emitted from SNRs are harder than those due to CR collisions with the ISM. The secondary-to-primary ratios flatten significantly at \\simTeV/n energies, both from spallation and re-acceleration in the sources. The two mechanisms are complementary to each other and depend on the properties of the local ISM around the expanding remnants. The seconda...

Tomassetti, N

2012-01-01

336

MOLECULAR CLOUDS AS A PROBE OF COSMIC-RAY ACCELERATION IN A SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

We study cosmic-ray acceleration in a supernova remnant (SNR) and the escape from it. We model nonthermal particle and photon spectra for the hidden SNR in the open cluster Westerlund 2, and the old-age mixed-morphology SNR W 28. We assume that the SNR shock propagates in a low-density cavity, which is created and heated through the activities of the progenitor stars and/or previous supernova explosions. We indicate that the diffusion coefficient for cosmic rays around the SNRs is less than ?1% of that away from them. We compare our predictions with the gamma-ray spectra of molecular clouds illuminated by the cosmic rays (Fermi and H.E.S.S.). We found that the spectral indices of the particles are ?2.3. This may be because the particles were accelerated at the end of the Sedov phase, and because energy-dependent escape and propagation of particles did not much affect the spectrum.

2009-12-20

337

A Chandra View Of Nonthermal Emission In The Northwestern Region Of Supernova Remnant RCW 86: Particle Acceleration And Magnetic Fields  

CERN Document Server

The shocks of supernova remnants (SNRs) are believed to accelerate particles to cosmic ray (CR) energies. The amplification of the magnetic field due to CRs propagating in the shock region is expected to have an impact on both the emission from the accelerated particle population, as well as the acceleration process itself. Using a 95 ks observation with the Advanced CCD Imaging Spectrometer (ACIS) onboard the Chandra X-ray Observatory, we map and characterize the synchrotron emitting material in the northwestern region of RCW 86. We model spectra from several different regions, filamentary and diffuse alike, where emission appears dominated by synchrotron radiation. The fine spatial resolution of Chandra allows us to obtain accurate emission profiles across 3 different non-thermal rims in this region. The narrow width (l = 10''-30'') of these filaments constrains the minimum magnetic field strength at the post-shock region to be approximately 80 {\\mu}G.

Castro, Daniel; Slane, Patrick O; Yamaguchi, Hiroya; Ramirez-Ruiz, Enrico; Figueroa-Feliciano, Enectali

2013-01-01

338

SUPERNOVA REMNANTS AND THE INTERSTELLAR MEDIUM OF M83: IMAGING AND PHOTOMETRY WITH THE WIDE FIELD CAMERA 3 ON THE HUBBLE SPACE TELESCOPE  

International Nuclear Information System (INIS)

We present Wide Field Camera 3 images taken with the Hubble Space Telescope within a single field in the southern grand design star-forming galaxy M83. Based on their size, morphology, and photometry in continuum-subtracted H?, [S II], H?, [O III], and [O II] filters, we have identified 60 supernova remnant (SNR) candidates, as well as a handful of young ejecta-dominated candidates. A catalog of these remnants, their sizes and, where possible, their H? fluxes are given. Radiative ages and pre-shock densities are derived from those SNRs that have good photometry. The ages lie in the range 2.62 rad/yr) 0/cm-3 min = 16+7-5 Msun. Finally, we give evidence for the likely detection of the remnant of the historical supernova, SN1968L.

2010-02-20

339

A method to identify the companion stars of type Ia supernovae in young supernova remnants  

CERN Document Server

We propose a method to identify the companion stars of type Ia supernovae (SNe Ia) in young supernova remnants (SNRs) by recognizing distinct features of absorption lines due to Fe I appearing in the spectrum. If a sufficient amount of Fe I remains in the ejecta, Fe I atoms moving toward us absorb photons by transitions from the ground state to imprint broad absorption lines exclusively with the blue-shifted components in the spectrum of the companion star. To investigate the time evolution of column depth of Fe I in the ejecta, we have performed hydrodynamical calculations for SNRs expanding into the uniform ambient media, taking into account collisional ionizations, excitations, and photo-ionizations of heavy elements. As a result, it is found that the companion star in Tycho's SNR will exhibit observable features in absorption lines due to Fe I at $\\lambda\\lambda = 371.9935$ nm and 385.9911 nm if a carbon deflagration SN model is taken. However, these features may disappear by taking another model that emi...

Shigeyama, J O T

2006-01-01

340

A New X-Ray View of the Supernova Remnant G272.2–3.2 and Its Environment  

Science.gov (United States)

We present an analysis of Chandra X-Ray Observatory data detailing a Galactic supernova remnant, G272.2–3.2. A clear shell of emission is resolved as a series of filaments and knots around the entire rim of the remnant. Spectral analysis of these features show that they are consistent with shock heating of interstellar material in a clumpy medium. We contrast these X-ray images with 22 ?m Wide-field Infrared Survey Explorer (WISE) data to verify this interaction. Spatially separated from the shell we see a central diffuse region dominated by harder, hotter emission. Spatial spectroscopy shows a clear enhancement of metals consistent with a Type Ia explosion, namely S, Si, and Fe. We find no clear evidence for a compact object or pulsar wind nebula and argue for a Type Ia origin. Consideration of the ionization timescales suggest an age of 11,000 yr for G272.2–3.2.

McEntaffer, R. L.; Grieves, N.; DeRoo, C.; Brantseg, T.

2013-09-01

 
 
 
 
341

A NEW X-RAY VIEW OF THE SUPERNOVA REMNANT G272.2-3.2 AND ITS ENVIRONMENT  

Energy Technology Data Exchange (ETDEWEB)

We present an analysis of Chandra X-Ray Observatory data detailing a Galactic supernova remnant, G272.2-3.2. A clear shell of emission is resolved as a series of filaments and knots around the entire rim of the remnant. Spectral analysis of these features show that they are consistent with shock heating of interstellar material in a clumpy medium. We contrast these X-ray images with 22 {mu}m Wide-field Infrared Survey Explorer (WISE) data to verify this interaction. Spatially separated from the shell we see a central diffuse region dominated by harder, hotter emission. Spatial spectroscopy shows a clear enhancement of metals consistent with a Type Ia explosion, namely S, Si, and Fe. We find no clear evidence for a compact object or pulsar wind nebula and argue for a Type Ia origin. Consideration of the ionization timescales suggest an age of 11,000 yr for G272.2-3.2.

McEntaffer, R. L.; Grieves, N.; DeRoo, C.; Brantseg, T., E-mail: randall-mcentaffer@uiowa.edu [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)

2013-09-10

342

X-ray surface brightness of Kepler's supernova remnant  

Energy Technology Data Exchange (ETDEWEB)

We have observed Kepler's supernova remnant (SNR) with the imaging instruments on board the Einstein Observatory. The 0.15-4.5 keV flux incident on the Earth is 1.2 x 10/sup -10/ ergs cm/sup -2/ s/sup -1/; the flux corrected for interstellar absorption is 3.4 x 10/sup -10/ ergs cm/sup -2/ s/sup -1/ (L/sub x/ = 1.0 x 10/sup 36/ ergs s/sup -1/ at D = 5 kpc) if the absorbing column density is N/sub H/ = 2.8 x 10/sup 21/ cm/sup -2/. The remnant is circular and shows a strong shell which is at least 5 times brighter in the north than in the south. The X-ray observations do not unambiguously determine whether the remnant is in the adiabatic or the free expansion phase. If the remnant is in the adiabatic phase, the density of the interstellar medium (ISM) (/sup 1/2/) surrounding Kepler's SNR must be about 5 cm/sup -3/. If the remnant is in the free expansion phase, where most of the emission arises from shock-heated ejecta, the ISM density must still be relatively high, n/sub i/> or approx. =0.1 cm/sup -3/. Even if the ISM is very inhomogeneous, with very many small, dense clouds, we show that the mean density of the ISM must be greater than approx.0.1 cm/sup -3/. In any case, the density of the x-ray emitting gas must be high (/sup 1/2/ > or approx. =10 cm/sup -3/), and the temperature must be fairly low (T/sub e/< or approx. =2 x 10/sup 7/ K). The relatively high ISM density which is required is surprising in view of Kepler's distance above the galactic plane, approx.600 pc. Possibly the ISM around Kepler's SNR and around other type i SNRs is dominated by the mass lost from the presupernova star.

White, R.L.; Long, K.S.

1983-01-01

343

Nonthermal emission properties of the northwestern rim of supernova remnant RX J0852.0-4622  

Science.gov (United States)

The supernova remnant (SNR) RX J0852.0-4622 (Vela Jr., G266.6-1.2) is one of the most important SNRs for investigating the acceleration of multi-TeV particles and the origin of Galactic cosmic rays because of its strong synchrotron X-ray and TeV ?-ray emission, which show a shell-like morphology similar to each other. Using the XMM-Newton archival data consisting of multiple pointing observations of the northwestern rim of the remnant, we investigate the spatial properties of the nonthermal X-ray emission as a function of distance from an outer shock wave. All X-ray spectra are well reproduced by an absorbed power-law model above 2 keV. It is found that the spectra show gradual softening from a photon index ? = 2.56 in the rim region to ? = 2.96 in the interior region. We show that this radial profile can be interpreted as a gradual decrease of the cutoff energy of the electron spectrum due to synchrotron cooling. By using a simple spectral evolution model that includes continuous synchrotron losses, the spectral softening can be reproduced with the magnetic field strength in the post-shock flow to less than several tens of ?G. If this is a typical magnetic field in the SNR shell, ?-ray emission would be accounted for by inverse Compton scattering of high-energy electrons that also produce the synchrotron X-ray emission. Future hard X-ray imaging observations with Nustar and ASTRO-H and TeV ?-ray observations with the Cherenkov Telescope Array (CTA) will allow us to explore other possible explanations of the systematic softening of the X-ray spectra.

Kishishita, T.; Hiraga, J.; Uchiyama, Y.

2013-03-01

344

Cosmic-ray acceleration in supernova remnants: non-linear theory revised  

CERN Multimedia

A rapidly growing amount of evidences, mostly coming from the recent gamma-ray observations of Galactic supernova remnants (SNRs), is seriously challenging our understanding of how particles are accelerated at fast shocks. The cosmic-ray (CR) spectra required to account for the observed phenomenology are in fact as steep as $E^{-2.2}--E^{-2.4}$, i.e., steeper than the test-particle prediction of first-order Fermi acceleration, and significantly steeper than what expected in a more refined non-linear theory of diffusive shock acceleration. By accounting for the dynamical back-reaction of the non-thermal particles, such a theory in fact predicts that the more efficient the particle acceleration, the flatter the CR spectrum. In this work we put forward a self-consistent scenario in which the account for the magnetic field amplification induced by CR streaming produces the conditions for reversing such a trend, allowing --- at the same time --- for rather steep spectra and CR acceleration efficiencies (about 20%)...

Caprioli, Damiano

2012-01-01

345

An Extreme Pulsar Tail Protruding from the Frying Pan Supernova Remnant  

CERN Document Server

The Frying Pan (G315.9-0.0) is a radio supernova remnant with a peculiar linear feature extending 10' radially outward from the rim of the shell. We present radio imaging and polarization observations with the Molonglo Observatory Synthesis Telescope and the Australia Telescope Compact Array, confirming the linear structure as a bow-shock pulsar wind nebula powered by the young pulsar J1437-5959. Extending over 20pc, this is the longest pulsar tail observed. We found a stand-off distance of 0.002pc, smallest among any bow-shock systems, suggesting a large pulsar velocity over 1000km/s and a high Mach number ~200. The magnetic field geometry inferred from radio polarimetry shows a good alignment with the tail orientation, which could be a result of high flow speed. There are also hints that the postshock wind has a low magnetization and is dominated by electrons and positrons in energy. This study shows that pulsar wind nebulae can offer a powerful probe of the pulsar environment, particularly for the case of ...

Ng, C -Y; Gaensler, B M; Camilo, F; Chatterjee, S; Bouchard, A

2011-01-01

346

Submillimeter/millimeter observations of the molecular clouds associated with Tycho's supernova remnant  

International Nuclear Information System (INIS)

We have carried out CO J = 2 - 1 and CO J = 3 - 2 observations toward Tycho's supernova remnant (SNR) using the KOSMA 3m-telescope. From these observations, we identified three molecular clouds (MCs) around the SNR. The small cloud in the southwest was discovered for the first time. In the north and east, two MCs (Cloud A and Cloud B) adjacent in space display a bow-shaped morphology, and have broad emission lines, which provide some direct evidences of the SNR-MCs interaction. The MCs are revealed at -69? -59 km s-1, coincident with Tycho's SNR. The MCs associated with Tycho's SNR have a mass of ? 2.13 x 103 Mcircleddot. Position-velocity diagrams show the two clouds to be adjacent in velocity, which means cloud-cloud collision could occur in this region. The maximum value (0.66 ± 0.10) of the integrated CO line intensity ratio (ICOJ=3-2/ICOJ=2-1) for the three MCs agrees well with the previous measurement of individual Galactic MCs, implying that the SNR shock drove into the MCs. The two MCs have a line intensity ratio gradient. The distribution of the ratio appears to indicate that the shock propagates from the southwest to the northeast.

1000-01-00

347

The multi-band nonthermal emission from the supernova remnant RX J1713.7-3946  

CERN Multimedia

Nonthermal X-rays and very high-energy (VHE) $\\gamma$-rays have been detected from the supernova remnant (SNR) RX J1713.7-3946, and especially the recent observations with the \\textit{Suzaku} satellite clearly reveal a spectral cutoff in the X-ray spectrum, which directly relates to the cutoff of the energy spectrum of the parent electrons. However, whether the origin of the VHE $\\gamma$-rays from the SNR is hadronic or leptonic is still in debate. We studied the multi-band nonthermal emission from RX J1713.7-3946 based on a semi-analytical approach to the nonlinear shock acceleration process by including the contribution of the accelerated electrons to the nonthermal radiation. The results show that the multi-band observations on RX J1713.7-3946 can be well explained in the model with appropriate parameters and the TeV $\\gamma$-rays have hadronic origin, i.e., they are produced via proton-proton (p-p) interactions as the relativistic protons accelerated at the shock collide with the ambient matter.

Fang, J; Zhang, J F; Tang, Y Y; Yu, H; 10.1111/j.1365-2966.2008.14128.x

2009-01-01

348

The X-ray spectrum of Kepler's supernova remnant  

International Nuclear Information System (INIS)

[en] Kepler's SNR was observed with the Large Area Counter on board the Ginga satellite in the energy range 1-12 keV. A strong iron K? emission line has been found at 6.48±0.07 keV. This value is too low if the plasma has reached the collisional ionization equilibrium (CIE) condition and, therefore, indicates that the plasma is still in a non-equilibrium ionization (NEI) condition. Using a NEI model, we determined the electron temperature, Te, to be 4.5±0.3 keV, and the plasma parameter, ? (the product of the electron number density n and the elapsed time t after the shock heating), to be 1010.24±0.03 cm-3 s. We also determined the abundances of heavy elements, and found that iron is overabundant by a factor of 15±2 compared to the cosmic value. The iron mass within the remnant was estimated to be about 0.01 (solar mass), which is less than one tenth of that predicted by the theory for Type ISN. We also discuss the differences between Kepler's and Tycho's SNRs. (author)

1990-01-01

349

The acceleration of cosmic-ray protons in the supernova remnant RX J1713.7-3946  

CERN Document Server

Protons with energies up to 10^15 eV are the main component[1] of cosmic rays, but evidence for the specific locations where they could have been accelerated to these energies has been lacking[2]. Electrons are known to be accelerated to cosmic-ray energies in supernova remnants[3, 4], and the shock waves associated with such remnants, when they hit the surrounding interstellar medium, could also provide the energy to accelerate protons. The signature of such a process would be the decay of pions (pi0), which are generated when the protons collide with atoms and molecules in an interstellar cloud: pion decay results in g-rays with a particular spectral-energy distribution[5, 6]. Here we report the observation of cascade showers of optical photons resulting fromg-rays at energies of 10^12 eV hitting Earth's upper atmosphere, in the direction of the supernova remnant RX J1713.7-3946. The spectrum is a good match to that predicted by pion decay, and cannot be explained by other mechanisms.

Enomoto, R

2002-01-01

350

The interaction of a supernova remnant with interstellar clouds using high order local adaptive mesh refinement methods  

International Nuclear Information System (INIS)

The interaction between supernova remnants (SNR) and interstellar clouds in the galaxy is known to play a major role in determining the structure of the interstellar medium (ISM). We know that the ISM is highly inhomogeneous, consisting of both diffuse atomic clouds (T?100K) and dense molecular clouds (T?10K) surrounded by a low density warm ionized gas (T?104K) and by a very hot coronal gas (T?106K). Next to radiation directly from stars, supernova explosions represent the most important form of energy injection into the ISM; they determine the velocity of interstellar clouds, accelerate cosmic rays, and can compress clouds to gravitational instability, possibly spawning a new generation of star formation. The shock waves from supernova remnants can compress, accelerate, disrupt and render hydrodynamically unstable interstellar clouds, thereby ejecting mass back into the intercloud medium. Thus, while the interaction of the SNR blast wave with cloud inhomogeneities can clearly alter the appearance of the ISM, the cloud inhomogeneities can similarly have a profound effect on the structure of the SNR.

1992-01-01

351

The Fermi Bubbles as a Scaled-up Version of Supernova Remnants  

Science.gov (United States)

In this study, we treat Fermi bubbles as a scaled-up version of supernova remnants (SNRs). The bubbles are created through activities of the super-massive black hole (SMBH) or starbursts at the Galactic center (GC). Cosmic-rays (CRs) are accelerated at the forward shocks of the bubbles like SNRs, which means that we cannot decide whether the bubbles were created by the SMBH or starbursts from the radiation from the CRs. We follow the evolution of CR distribution by solving a diffusion-advection equation, considering the reduction of the diffusion coefficient by CR streaming. In this model, gamma rays are created through hadronic interaction between CR protons and the gas in the Galactic halo. In the GeV band, we can well reproduce the observed flat distribution of gamma-ray surface brightness because some amount of gas is left behind the shock. The edge of the bubbles is fairly sharp owing to the high gas density behind the shock and the reduction of the diffusion coefficient there. The latter also contributes the hard gamma-ray spectrum of the bubbles. We find that the CR acceleration at the shock began when the bubbles were small, and the time scale of the energy injection at the GC was much smaller than the age of the bubbles. We predict that if CRs are accelerated to the TeV regime, the apparent bubble size should be larger in the TeV band, which could be used to discriminate our hadronic model from other leptonic models. We also present neutrino fluxes.

Fujita, Yutaka; Ohira, Yutaka; Yamazaki, Ryo

2013-09-01

352

Distribution of interstellar matter toward Tycho's Supernova Remnant and its relation to distance estimates  

International Nuclear Information System (INIS)

[en] Observations of interstellar absorption lines in the spectra of five stars in the direction of Tycho's Supernova Remnant are presented. The profiles show significant absorption at large negative velocities, -50 to -60 km s-1 (LSR). This information, together with the distances of the background stars, permits limiting distances to be assigned to the corresponding velocity components in the H I 21-cm line absorption spectrum of the supernova remnant itself. The 21-cm absorption line data for Tycho's Supernova Remnant are entirely consistent with a distance as small as 2 kpc. Distances based upon simple kinematic models of galactic rotation can be confused by well-known noncircular motions in this direction. The interstellar line data also reveal a relatively high column density of CO toward HD 108

1984-01-01

353

Multifrequency study of SNR J0533-7202, a new supernova remnant in the LMC  

CERN Multimedia

We present a detailed study of Australia Telescope Compact Array (ATCA) observations of a newly discovered Large Magellanic Cloud (LMC) supernova remnant (SNR), SNR J0533-7202. This object follows a horseshoe morphology, with a size 37 pc x 28 pc (1-pc uncertainty in each direction). It exhibits a radio spectrum with the intrinsic synchrotron spectral index of alpha= -0.47+-0.06 between 73 and 6 cm. We report detections of regions showing moderately high fractional polarisation at 6 cm, with a peak value of 36+-6% and a mean fractional polarisation of 12+-7%. We also estimate an average rotation measure across the remnant of -591 rad m^-2. The current lack of deep X-ray observation precludes any conclusion about high-energy emission from the remnant. The association with an old stellar population favours a thermonuclear supernova origin of the remnant.

Bozzetto, L M; Crawford, E J; Sasaki, M; Maggi, P; Haberl, F; Uroševi?, D; Payne, J L; De Horta, A Y; Stupar, M; Gruendl, R; Dickel, J

2013-01-01

354

Fermi-LAT Discovery of Extended Gamma-ray Emission in the Direction of Supernova Remnant W51C  

CERN Multimedia

The discovery of bright gamma-ray emission coincident with supernova remnant (SNR) W51C is reported using the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. W51C is a middle-aged remnant (~10^4 yr) with intense radio synchrotron emission in its shell and known to be interacting with a molecular cloud. The gamma-ray emission is spatially extended, broadly consistent with the radio and X-ray extent of SNR W51C. The energy spectrum in the 0.2-50 GeV band exhibits steepening toward high energies. The luminosity is greater than 1x10^{36} erg/s given the distance constraint of D>5.5 kpc, which makes this object one of the most luminous gamma-ray sources in our Galaxy. The observed gamma-rays can be explained reasonably by a combination of efficient acceleration of nuclear cosmic rays at supernova shocks and shock-cloud interactions. The decay of neutral pi-mesons produced in hadronic collisions provides a plausible explanation for the gamma-ray emission. The product of the average gas dens...

,

2009-01-01

355

Search for cosmic ray origins by the study of supernova remnants associated with molecular clouds with HESS and test of HESS II sampling system  

International Nuclear Information System (INIS)

The H.E.S.S. telescope (High energy Stereoscopic System), located in Namibia, is currently the most efficient for the observation of very high energy (VHE) gamma-ray sources. It is composed of 4 large diameter telescopes working in stereoscopic mode and allows an unequaled survey of the galactic plane at these extreme wavelengths. The H.E.S.S. experiment showed the presence of high energy particles up to 100 TeV within supernova remnant. This astrophysical objects are believed to be the main particle accelerator within the Galaxy. However, the particle nature remains unclear. This thesis presents a new observational approach in order to show hadronic particles acceleration through diffusive shock within supernova remnant. A search of supernova remnant associated with molecular cloud have been led within the HESS source catalog and the H.E.S.S. observations. An analysis of the new VHE gamma-ray source in Monoceros and its interpretation are presented. As well, the analysis and interpretation of new observations of the unidentified source HESS J1745-303 are presented. The multi-wavelength analysis of the new source HESS J1714-385, coincident with the supernova remnant CTB37A is presented. A contribution to the H.E.S.S. phase II building is also presented. This second phase consists in the building of a fifth telescope at the center of the existing system. The series tests of the new camera sampling system are reported. (author)

2008-01-01

356

Chandra View of DA 530: A Sub-Energetic Supernova Remnant with a Pulsar Wind Nebula?  

CERN Document Server

DA 530 (G93.3+6.9) is a high Galactic latitude supernova remnant with a well-defined shell-like radio morphology and an exceptionally low X-ray to radio luminosity ratio. Based on a Chandra ACIS observation, we report the detection of an extended X-ray feature close to the center of the remnant with 5.3 sigma above the background within a circle of 20''

Jiang, Bing; Wang, Q Daniel

2007-01-01

357

Infrared spectroscopy of young supernova remnants heavily interacting with the interstellar medium. I. Ionizes species in RCW 103  

CERN Document Server

ISO spectral observations of the supernova remnant RCW103 are presented. This object is the prototype of relatively young remnants with fast shocks interacting with dense interstellar medium. The spectrum is dominated by prominent lines of [NeII], [SiII], [FeII] and other low excitation species which provide, for the first time, a simple and reliable estimate of the gas abundances of refractory (Si, Fe, Ni) and non-refractory (Ne, P, S, Cl, Ar) species. Apart from nickel, all the derived abundances are close to solar, confirming that the shock has destroyed all dust grains. Like the optical nickel lines, [NiII] 6.64micron yields Ni abundances a factor ~10 solar which we propose results from a large underestimation of the computed Ni+ collision strengths. The observed intensities and velocity widths of ionic lines are compatible with emission from the post-shock region alone with only a very small (if any) contribution from the photoionized precursor. This result does not agree with shock models which predict ...

Oliva, E; Drapatz, S; Lutz, D; Sturm, E

1999-01-01

358

Fast radiation mediated shocks and supernova shock breakouts  

CERN Multimedia

We present a simple analytic model for the structure of non-relativistic and relativistic radiation mediated shocks. At shock velocities \\beta_s\\equiv v_s/c\\gtrsim 0.1, the shock transition region is far from thermal equilibrium, since the transition crossing time is too short for the production of a black-body photon density (by Bremsstrahlung emission). In this region, electrons and photons (and positrons) are in Compton (pair) equilibrium at temperatures T_s significantly exceeding the far downstream temperature, T_s\\gg T_d\\approx 2(\\varepsilon n_u \\hbar^3c^3)^{1/4}. T_s\\gtrsim 10 keV is reached at shock velocities \\beta_s\\approx 0.2. At higher velocities, \\beta_s\\gtrsim0.6, the plasma is dominated in the transition region by e^\\pm pairs and 60 keV\\lesssim T_s \\lesssim 200 keV. We argue that the spectrum emitted during the breaking out of supernova shocks from the stellar envelopes (or the surrounding winds) of Blue Super Giants and Wolf-Rayet stars, which reach \\beta_s>0.1 for reasonable stellar parameter...

Katz, Boaz; Waxman, Eli

2009-01-01

359

AKARI Detection of the Infrared-Bright Supernova Remnant B0104-72.3 in the Small Magellanic Cloud  

CERN Multimedia

We present a serendipitous detection of the infrared-bright supernova remnant (SNR) B0104-72.3 in the Small Magellanic Cloud by the Infrared Camera (IRC) onboard AKARI. An elongated, partially complete shell is detected in all four observed IRC bands covering 2.6-15 um. The infrared shell surrounds radio, optical, and X-ray emission associated with the SNR and is probably a radiative SNR shell. This is the first detection of a SNR shell in this near/mid-infrared waveband in the Small Magellanic Cloud. The IRC color indicates that the infrared emission might be from shocked H2 molecules with some possible contributions from ionic lines. We conclude that B0104-72.3 is a middle-aged SNR interacting with molecular clouds, similar to the Galactic SNR IC 443. Our results highlight the potential of AKARI IRC observations in studying SNRs, especially for diagnosing SNR shocks.

Koo, Bon-Chul; Moon, Dae-Sik; Lee, Jae-Joon; Seok, Ji Yeon; Lee, Hyung Mok; Hong, Seung Soo; Lee, Myung Gyoon; Kaneda, Hidehiro; Ita, Yoshifusa; Jeong, Woong-Seob; Onaka, Takashi; Sakon, Itsuki; Nakagawa, Takao; Murakami, Hiroshi

2007-01-01

360

XMM-Newton detection of the supernova remnant G304.6+0.1 (Kes 17)  

Science.gov (United States)

Aims: We report the first detailed X-ray study of the supernova remnant (SNR) G304.6+0.1, achieved with the XMM-Newton mission. Methods: The powerful imaging capability of XMM-Newton was used to study the X-ray characteristics of the remnant at different energy ranges. The X-ray morphology and spectral properties were analyzed. In addittion, radio and mid-infrared data obtained with the Molonglo Observatory Synthesis Telescope and the Spitzer Space Telescope were used to study the association with the detected X-ray emission and to understand the structure of the SNR at differents wavelengths. Results: The SNR shows an extended and arc-like internal structure in the X-ray band without a compact point-like source inside the remnant. We find a high column density of NH in the range 2.5-3.5 × 1022 cm-2, which supports a relatively distant location (d ? 9.7 kpc). The X-ray spectrum exhibits at least three emission lines, indicating that the X-ray emission has a thin thermal plasma origin, although a non-thermal contribution cannot be discarded. The spectra of three different regions (north, center and south) are well represented by a combination of a non-equilibrium ionization (PSHOCK) and a power-law (PL) model. The mid-infrared observations show a bright filamentary structure along the north-south direction coincident with the NW radio shell. This suggests that Kes 17 is propagating in a non-uniform environment with high density and that the shock front is interacting with several adjacent massive molecular clouds. The good correspondence of radio and mid-infrared emissions suggests that the filamentary features are caused by shock compression. The X-ray characteristics and well-known radio parameters indicate that G304.6+0.1 is a middle-aged SNR (2.8-6.4) × 104 yr old and a new member of the recently proposed group of mixed-morphology SNRs.

Combi, J. A.; Albacete Colombo, J. F.; Sánchez-Ayaso, E.; Romero, G. E.; Martí, J.; Luque-Escamilla, P. L.; Muñoz-Arjonilla, A. J.; Sánchez-Sutil, J. R.; López-Santiago, J.

2010-11-01

 
 
 
 
361

DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY  

International Nuclear Information System (INIS)

A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M ?

2012-11-10

362

DEM L241, a Supernova Remnant containing a High-Mass X-ray Binary  

CERN Document Server

A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a High-Mass X-ray Binary (HMXB) with orbital period likely to be of order tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass > 25 solar masses

Seward, F D; Foster, D L; Dickel, J R; Romero, P S; Edwards, Z I; Perry, M; Williams, R M

2012-01-01

363

DEM L241, A SUPERNOVA REMNANT CONTAINING A HIGH-MASS X-RAY BINARY  

Energy Technology Data Exchange (ETDEWEB)

A Chandra observation of the Large Magellanic Cloud supernova remnant DEM L241 reveals an interior unresolved source which is probably an accretion-powered binary. The optical counterpart is an O5III(f) star making this a high-mass X-ray binary with an orbital period likely to be of the order of tens of days. Emission from the remnant interior is thermal and spectral information is used to derive density and mass of the hot material. Elongation of the remnant is unusual and possible causes of this are discussed. The precursor star probably had mass >25 M {sub Sun}.

Seward, F. D. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Charles, P. A. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Foster, D. L. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa); Dickel, J. R.; Romero, P. S. [Department of Physics and Astronomy, University of New Mexico, 1919 Lomas Boulevard NE, Albuquerque, NM 87131 (United States); Edwards, Z. I.; Perry, M.; Williams, R. M. [Department of Earth and Space Sciences, Columbus State University, Coca Cola Space Science Center, 701 Front Avenue, Columbus, GA 31901 (United States)

2012-11-10

364

Modelling of X-ray emission supernova remnants observed by the European satellite XMM-Newton  

International Nuclear Information System (INIS)

This thesis deals with the X-ray emission of supernova remnants (SNRs) observed by the European satellite XMM-Newton. In SNRs, the matter heated to millions of degrees shines brightly in X-rays. This emission depends on the hydrodynamical evolution of the SNR, on the chemical composition of the ejected matter and on the ambient medium. Moreover, the blast-wave is considered to be the prime site of the production and the acceleration of cosmic-rays in our Galaxy. XMM-Newton is one of the first to allow the investigation of these different aspects thanks to its spatially-resolved spectroscopy and its very good sensitivity. l first studied Kepler's SNR (SN 1604) whose X-ray emission is dominated by the ejecta. Its observation has allowed to obtain information on the nucleosynthesis products, on their spatial distribution and on the temperature structure in the shocked ejecta. This gives strong constraints on the physics of the explosion and on the progenitor's type. l have shown also that the X-ray emission at the shock is likely to be non-thermal. Then, l studied the SNR G347.3-0.5 whose X-ray emission is entirely due to the synchrotron radiation of relativistic (TeV) electrons accelerated at the shock. From five pointing, l made a full mapping of the X-ray emission characteristics (brightness, absorption and spectral index) at small scale. Combined to radio observations, these results have indicated a clear interaction between the SNR and molecular clouds located at 1 kpc and not at 6 kpc as previously estimated. Lastly, in the framework of a self-similar hydrodynamical model coupled with non-linear particle acceleration, l have obtained the synchrotron emission profile in SNRs, including the adiabatic and radiative losses of the accelerated electrons. (author)

2004-01-01

365

X-ray emission from the remnant of a carbon deflagration supernova - SN 1572 (Tycho)  

International Nuclear Information System (INIS)

[en] A spherically symmetric hydrodynamic code is used to study the evolution of a young supernova remnant on the basis of a carbon deflagration model for type Ia supernovae. The nonequilibrium X-ray emission has been determined for the elemental composition of the model. The discrepancy between the derived intensity of the Fe D-alpha line blend and the observed value is eliminated by assuming that the stratification of the elemental composition in the supernova ejecta is partially removed by mixing. 59 references

1988-01-01

366

X-ray emission from the remnant of a carbon deflagration supernova - SN 1572 (Tycho)  

Energy Technology Data Exchange (ETDEWEB)

A spherically symmetric hydrodynamic code is used to study the evolution of a young supernova remnant on the basis of a carbon deflagration model for type Ia supernovae. The nonequilibrium X-ray emission has been determined for the elemental composition of the model. The discrepancy between the derived intensity of the Fe D-alpha line blend and the observed value is eliminated by assuming that the stratification of the elemental composition in the supernova ejecta is partially removed by mixing. 59 references.

Itoh, H.; Masai, K.; Nomoto, K.

1988-11-01

367

Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006  

Science.gov (United States)

A joint spectral analysis of some Chandra ACIS X-ray data and Molonglo Observatory Synthesis Telescope radio data was performed for 13 small regions along the bright northeastern rim of the supernova remnant SN 1006. These data were fitted with a synchrotron radiation model. The nonthermal electron spectrum used to compute the photon emission spectra is the traditional exponentially cut off power law, with one notable difference: The power-law index is not a constant. It is a linear function of the logarithm of the momentum. This functional form enables us to show, for the first time, that the synchrotron spectrum of SN 1006 seems to flatten with increasing energy. The effective power-law index of the electron spectrum is 2.2 at 1 GeV (i.e., radio synchrotron-emitting momenta) and 2.0 at about 10 TeV (i.e., X-ray synchrotron-emitting momenta). This amount of change in the index is qualitatively consistent with theoretical models of the amount of curvature in the proton spectrum of the remnant. The evidence of spectral curvature implies that cosmic rays are dynamically important instead of being ``test'' particles. The spectral analysis also provides a means of determining the critical frequency of the synchrotron spectrum associated with the highest-energy electrons. The critical frequency seems to vary along the northeastern rim, with a maximum value of 1.1+1.0-0.5×1017 Hz. This value implies that the electron diffusion coefficient can be no larger than a factor of ~4.5-21 times the Bohm diffusion coefficient if the velocity of the forward shock is in the range 2300-5000 km s-1. Since the coefficient is close to the Bohm limit, electrons are accelerated nearly as fast as possible in the regions where the critical frequency is about 1017 Hz.

Allen, G. E.; Houck, J. C.; Sturner, S. J.

2008-08-01

368

THE MAGELLAN/IMACS CATALOG OF OPTICAL SUPERNOVA REMNANT CANDIDATES IN M83  

Energy Technology Data Exchange (ETDEWEB)

We present a new optical imaging survey of supernova remnants (SNRs) in M83, using data obtained with the Magellan I 6.5 m telescope and IMACS instrument under conditions of excellent seeing. Using the criterion of strong [S II] emission relative to H{alpha}, we confirm all but three of the 71 SNR candidates listed in our previous survey, and expand the SNR candidate list to 225 objects, more than tripling the earlier sample. Comparing the optical survey with a new deep X-ray survey of M83 with Chandra, we find that 61 of these SNR candidates have X-ray counterparts. We also identify an additional list of 46 [O III]-selected nebulae for follow-up as potential ejecta-dominated remnants, seven of which have associated X-ray emission that makes them strong candidates. Some of the other [O III]-bright objects could also be normal interstellar medium (ISM) dominated SNRs with shocks fast enough to doubly ionize oxygen, but with H{alpha} and [S II] emission faint enough to have been missed. A few of these objects may also be H II regions with abnormally high [O III] emission compared with the majority of M83 H II regions, compact nebulae excited by young Wolf-Rayet stars, or even background active galactic nuclei. The SNR H{alpha} luminosity function in M83 is shifted by a factor of {approx}4.5 times higher than for M33 SNRs, indicative of a higher mean ISM density in M83. We describe the search technique used to identify the SNR candidates and provide basic information and finder charts for the objects.

Blair, William P. [Henry A. Rowland Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Winkler, P. Frank [Department of Physics, Middlebury College, Middlebury, VT 05753 (United States); Long, Knox S., E-mail: wpb@pha.jhu.edu, E-mail: winkler@middlebury.edu, E-mail: long@stsci.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2012-11-15

369

THE MAGELLAN/IMACS CATALOG OF OPTICAL SUPERNOVA REMNANT CANDIDATES IN M83  

International Nuclear Information System (INIS)

We present a new optical imaging survey of supernova remnants (SNRs) in M83, using data obtained with the Magellan I 6.5 m telescope and IMACS instrument under conditions of excellent seeing. Using the criterion of strong [S II] emission relative to H?, we confirm all but three of the 71 SNR candidates listed in our previous survey, and expand the SNR candidate list to 225 objects, more than tripling the earlier sample. Comparing the optical survey with a new deep X-ray survey of M83 with Chandra, we find that 61 of these SNR candidates have X-ray counterparts. We also identify an additional list of 46 [O III]-selected nebulae for follow-up as potential ejecta-dominated remnants, seven of which have associated X-ray emission that makes them strong candidates. Some of the other [O III]-bright objects could also be normal interstellar medium (ISM) dominated SNRs with shocks fast enough to doubly ionize oxygen, but with H? and [S II] emission faint enough to have been missed. A few of these objects may also be H II regions with abnormally high [O III] emission compared with the majority of M83 H II regions, compact nebulae excited by young Wolf-Rayet stars, or even background active galactic nuclei. The SNR H? luminosity function in M83 is shifted by a factor of ?4.5 times higher than for M33 SNRs, indicative of a higher mean ISM density in M83. We describe the search technique used to identify the SNR candidates and provide basic information and finder charts for the objects.

2012-01-01

370

A statistical study of the correlation of galactic supernova remnants and spiral arms  

International Nuclear Information System (INIS)

A statistical study of the correlation of galactic supernova remnants with spiral arms and the disk is presented. SNR apparently have a larger radial scale length than disk stars. The authors estimate that only about 10 percent of the galactic SNR have been detected.

1988-01-01

371

Numerical code for fitting radial emission profile of a shell supernova remnant: Application  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present IDL (Interactive Data Language) codes for fitting a theoretical emission profile of a shell supernova remnant (SNR) to the mean profile of an SNR obtained from radio observations. Two considered theoretical models are: 1) a shell with constant emissivity and 2) a synchrotron shell with...

Opsenica Slobodan; Arbutina Bojan

372

A study of optical observing techniques for extra-galactic supernova remnants: Case of NGC300  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the results of a study of observational and identification techniques used for surveys and spectroscopy of candidate supernova remnants (SNRs) in the Sculptor Group galaxy NGC300. The goal of this study was to investigate the reliability of using [Sii]:H? ? 0.4 in optical SNR surveys ...

Millar W.C.; White G.L.; Filipovi? M.D.

373

High-resolution radial velocity mapping of optical filaments in evolved supernova remnants  

International Nuclear Information System (INIS)

The authors report on observations of the kinematical structure of optical filaments in evolved supernova remnants, using an imaging Fabry--Perot interferometer. The radial velocity characteristics as seen in [OIII] ?5007 emission in one area in the Cygnus Loop are described, where four kinematically different components contributing to the emission can be recognized.

1988-01-01

374

Multiwavelength comparison of Cassiopeia A and Tycho's supernova remnant  

Energy Technology Data Exchange (ETDEWEB)

A comparison of high resolution radio, optical, and X-ray images of two young supernova remnants (SNR), Cas A and Tycho, shows significant differences between them, Cas A probably broke into many small knots at the time of the initial explosion, whereas Tycho's SNR appears to be a more uniformly expanding blast wave.

Dickel, J.R.; Murray, S.S.; Morris, J.; Wells, D.C.

1982-06-01

375

Neutral pion emission from accelerated protons in the supernova remnant W44  

CERN Document Server

We present the AGILE gamma-ray observations in the energy range 50 MeV - 10 GeV of the supernova remnant (SNR) W44, one of the most interesting systems for studying cosmic-ray production. W44 is an intermediate-age SNR (20, 000 years) and its ejecta expand in a dense medium as shown by a prominent radio shell, nearby molecular clouds, and bright [SII] emitting regions. We extend our gamma-ray analysis to energies substantially lower than previous measurements which could not conclusively establish the nature of the radiation. We find that gamma-ray emission matches remarkably well both the position and shape of the inner SNR shocked plasma. Furthermore, the gamma-ray spectrum shows a prominent peak near 1 GeV with a clear decrement at energies below a few hundreds of MeV as expected from neutral pion decay. Here we demonstrate that: (1) hadron-dominated models are consistent with all W44 multiwavelength constraints derived from radio, optical, X-ray, and gamma-ray observations; (2) ad hoc lepton-dominated mod...

Giuliani, A; Tavani, M; Fukui, Y; Yoshiike, S; Torii, K; Dubner, G; Castelletti, G; Barbiellini, G; Bulgarelli, A; Caraveo, P; Costa, E; Cattaneo, P W; Chen, A; Contessi, T; Del Monte, E; Donnarumma, I; Evangelista, Y; Feroci, M; Gianotti, F; Lazzarotto, F; Lucarelli, F; Longo, F; Marisaldi, M; Mereghetti, S; Pacciani, L; Pellizzoni, A; Piano, G; Picozza, P; Pittori, C; Pucella, G; Rapisarda, M; Rappoldi, A; Sabatini, S; Soffitta, P; Striani, E; Trifoglio, M; Trois, A; Vercellone, S; Verrecchia, F; Vittorini, V; Colafrancesco, S; Giommi, P; Bignami, G

2011-01-01

376

Suzaku Observation of 30Dor C: A Supernova Remnant with the Largest Non-Thermal Shell  

CERN Multimedia

This paper reports on the Suzaku results of thermal and non-thermal features of 30 Dor C, a supernova remnant (SNR) in a superbubble of the Large Magellanic Cloud (LMC). The west rim exhibits a non-thermal X-ray spectrum with no thermal component. A single power-law model is rejected but a power-law model with spectral cutoff is accepted. The cutoff frequency of $(3-7)\\times 10^{17}$ Hz is the highest among the shell type SNRs like SN 1006 ($\\sim 6\\times 10^{16}$ Hz), and hence 30 Dor C would be the site of the highest energy accelerator of the SNR shock. The southeast (SE) and northeast (NE) rims have both the thermal and non-thermal components. The thin-thermal plasmas in the both rims are in collisional ionization equilibrium state. The electron temperature of the plasma in the SE rim ($kT_e \\sim 0.7$ keV) is found to be higher than the previously reported value. The power-law index from SE is nearly the same as, while that from the NE is larger than that of the West rim. The SNR age would be in the range ...

Yamaguchi, Hiroya; Koyama, Katsuji

2008-01-01

377

Fermi Large Area Telescope Observations of the Cygnus Loop Supernova Remnant  

International Nuclear Information System (INIS)

We present an analysis of the gamma-ray measurements by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region of the supernova remnant (SNR) Cygnus Loop (G74.0-8.5). We detect significant gamma-ray emission associated with the SNR in the energy band 0.2-100 GeV. The gamma-ray spectrum shows a break in the range 2-3 GeV. The gamma-ray luminosity is ? 1 x 1033 erg s-1 between 1-100 GeV, much lower than those of other GeV-emitting SNRs. The morphology is best represented by a ring shape, with inner/outer radii 0o.7 ± 0o.1 and 1o.6 ± 0o.1. Given the association among X-ray rims, H? filaments and gamma-ray emission, we argue that gamma rays originate in interactions between particles accelerated in the SNR and interstellar gas or radiation fields adjacent to the shock regions. The decay of neutral pions produced in nucleon-nucleon interactions between accelerated hadrons and interstellar gas provides a reasonable explanation for the gamma-ray spectrum.

2011-11-01

378

FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE CYGNUS LOOP SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

We present an analysis of the gamma-ray measurements by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope in the region of the supernova remnant (SNR) Cygnus Loop (G74.0–8.5). We detect significant gamma-ray emission associated with the SNR in the energy band 0.2-100 GeV. The gamma-ray spectrum shows a break in the range 2-3 GeV. The gamma-ray luminosity is ?1 × 1033 erg s–1 between 1 and 100 GeV, much lower than those of other GeV-emitting SNRs. The morphology is best represented by a ring shape, with inner/outer radii 0.07 ± 0.01 and 1.06 ± 0.01. Given the association among X-ray rims, H? filaments, and gamma-ray emission, we argue that gamma rays originate in interactions between particles accelerated in the SNR and interstellar gas or radiation fields adjacent to the shock regions. The decay of neutral pions produced in nucleon-nucleon interactions between accelerated hadrons and interstellar gas provides a reasonable explanation for the gamma-ray spectrum.

2011-11-01

379

Magnetic Field Amplification in Tycho and other Shell-type Supernova Remnants  

CERN Multimedia

It is shown that amplification of the magnetic field in supernova remnants (SNRs) occurs in all six objects where morphological measurements are presently available in the hard X-ray continuum at several keV. For the three archetypical objects (SN 1006, Cas A and Tycho's SNR) to which nonlinear time-dependent acceleration theory has been successfully applied up to now, the global theoretical and the local observational field strengths agree very well, suggesting in addition that all young SNRs exhibit the amplification effect as a result of very efficient acceleration of nuclear cosmic rays (CRs) at the outer shock. Since this appears to be empirically the case, we may reverse the argument and consider field amplification as a measure of nuclear CR acceleration and it has indeed been argued that acceleration in the amplified fields allows the CR spectrum from SNRs to reach the knee in the spectrum or, in special objects, even beyond. The above results are furthermore used to investigate the time evolution of ...

Völk, H J; Ksenofontov, L T

2004-01-01

380

Submillimeter/millimeter observations of the molecular clouds associated with the Tycho' Supernova Remnant  

CERN Document Server

We have carried out CO J=2-1 and CO J=3-2 observations toward Tycho's supernova remnant (SNR) using the KOSMA 3m-Telescope. From these observations we identified three molecular clouds (MCs) around the SNR. The small cloud in the southwest was discovered for the first time. In the north and east, two MCs (cloud A and cloud B) adjacent in space display a bow-shaped morphology, and have broad emission lines, which provide some direct evidences of the SNR-MCs interaction. The MCs is revealed at -69~-59 km \\s, well coincident with the Tycho's SNR. The MCs associated with Tycho's SNR have a mass of ~2130 sun masses. Position-velocity diagrams show the two clouds adjacent in velocity which means possible cloud-cloud collision in this region. The maximum value (0.66) of integrated CO line intensity ratio I(CO J=3-2/CO J=2-1) for the three MCs agrees well with the previous measurement of individual Galactic MCs, implying that the SNR shock just drove into the MCs. The two MCs have a line intensity ratio gradient. The...

Xu, Jin-Long; Miller, Martin

2010-01-01

 
 
 
 
381

Dust processing in Supernova Remnants: Spitzer MIPS SED and IRS Observations  

CERN Multimedia

We present Spitzer MIPS SED and IRS observations of 14 Galactic Supernova Remnants previously identified in the GLIMPSE survey. We find evidence for SNR/molecular cloud interaction through detection of [OI] emission, ionic lines, and emission from molecular hydrogen. Through black-body fitting of the MIPS SEDs we find the large grains to be warm, 29-66 K. The dust emission is modeled using the DUSTEM code and a three component dust model composed of populations of big grains, very small grains, and polycyclic aromatic hydrocarbons. We find the dust to be moderately heated, typically by 30-100 times the interstellar radiation field. The source of the radiation is likely hydrogen recombination, where the excitation of hydrogen occurred in the shock front. The ratio of very small grains to big grains is found for most of the molecular interacting SNRs to be higher than that found in the plane of the Milky Way, typically by a factor of 2--3. We suggest that dust shattering is responsible for the relative over-abu...

Andersen, M; Reach, W T; Hewitt, J W; Bernard, J P

2011-01-01

382

Evolution Of Post-Impact Remnant Helium Stars In Type Ia Supernova Remnants Within The Single-Degenerate Scenario  

CERN Document Server

The progenitor systems of Type Ia supernovae (SNe Ia) are still under debate. Based on recent hydrodynamics simulations, non-degenerate companions in the single-degenerate scenario (SDS) should survive the supernova impact. One way to distinguish between the SDS and the double-degenerate scenario is to search for the post-impact remnant stars (PIRSs) in SN Ia remnants. Using a technique that combines multi-dimensional hydrodynamics simulations with one-dimensional stellar evolution simulations, we have examined the post-impact evolution of helium-rich binary companions in the SDS. It is found that these helium-rich PIRSs (He PIRSs) dramatically expand and evolve to a luminous phase ($L\\sim 10^4 L_\\odot$) about 10 years after a supernova explosion. Subsequently, they contract and evolve to become hot blue-subdwarf-like (sdO-like) stars by releasing gravitational energy, persisting as sdO-like stars for several million years before evolving to the helium red-giant phase. We therefore predict that an sdO-like st...

Pan, Kuo-Chuan; Taam, Ronald

2013-01-01

383

Hard X-ray Emission Clumps in the gamma-Cygni Supernova Remnant: an INTEGRAL-ISGRI View  

CERN Multimedia

Spatially resolved images of the galactic supernova remnant G78.2+2.1 (gamma-Cygni) in hard X-ray energy bands from 25 keV to 120 keV are obtained with the IBIS-ISGRI imager aboard the International Gamma-Ray Astrophysics Laboratory INTEGRAL. The images are dominated by localized clumps of about ten arcmin in size. The flux of the most prominent North-Western (NW) clump is (1.7 +/- 0.4) 10^{-11} erg/cm^2/s in the 25-40 keV band. The observed X-ray fluxes are in agreement with extrapolations of soft X-ray imaging observations of gamma-Cygni by ASCA GIS and spatially unresolved RXTE PCA data. The positions of the hard X-ray clumps correlate with bright patches of optical line emission, possibly indicating the presence of radiative shock waves in a shocked cloud. The observed spatial structure and spectra are consistent with model predictions of hard X-ray emission from nonthermal electrons accelerated by a radiative shock in a supernova interacting with an interstellar cloud, but the powerful stellar wind of th...

Bykov, A M; Uvarov, Y A; Blömen, H; Chevalier, R A; Gustov, M Y; Hermsen, W; Lebrun, F; Lozinskaya, T A; Rauw, G; Smirnova, T V; Sturner, S J; Swings, J P; Terrier, R; Toptygin, I N; Uvarov, Yu.A.

2004-01-01

384

A search for OH 6 GHz maser emission towards southern supernova remnants  

CERN Document Server

OH masers at 1720 MHz have proven to be excellent indicators of interactions between supernova remnants and molecular clouds. Recent calculations suggest that the 6049 MHz OH maser line is excited for higher column densities than for the 1720 MHz line. It is therefore a potentially valuable indicator of remnant-cloud interaction. We present preliminary results of a survey using the Parkes Methanol Multibeam receiver for 6049 MHz and 6035/6030 MHz OH masers towards 36 supernova remnants and 4 fields in the Large and Small Magellanic Clouds. While no 6049 MHz masers have been found, three new sites of 6035 and 6030 MHz OH maser emission have been discovered in star-forming regions.

McDonnell, Korinne E; Wardle, Mark

2007-01-01

385

X-ray emission from young supernova remnants: nonionization equilibrium abundances and emissivities  

Energy Technology Data Exchange (ETDEWEB)

X-ray line emission from hot, low-density plasma in young supernova remnants is strongly enhanced by departures from ionization equilibrium. We have calculated the X-ray emission from a Sedov blast wave, a nonequilibrium evolutionary treatment of the ionization structure, and have fitted the resulting spectrum to HEAO 2 SSS data for Tycho's remnant. These models yield dramatically different elemental abundances for heavy elements (Ne, Mg, Si, S, Ar, Ca, and Fe), compared with two-temperature component equilibrium models of Becker et al. Nonequilibrium broad-band X-ray emissivities result in lower mass determinations for the supernova ejecta. Areas of further improvement of remnant X-ray modeling are suggested.

Shull, J.M.

1982-11-01

386

sup 4 sup 4 Ti decay gamma-ray emission from young galactic supernova remnants  

CERN Multimedia

The discovery by COMPTEL of the sup 4 sup 4 Ti line emission at 1.16 MeV from the youngest known Galactic supernova remnant (SNR) Cas A has opened a new window for the investigation of SNR properties. This discovery also shows a way that could help to uncover missing young remnants of Galactic SNe that might have occurred some hundred years ago. Contrary to the situation at other wavelengths, in the gamma-ray band the Galaxy is almost transparent, so that otherwise obscured supernova remnants may be detectable up to A sub v approx 10 sup 3 in gamma-ray line emission. This is one of the direct ways to complement historical observations of Galactic SNe. Here we present preliminary results of the 6 year sup 4 sup 4 Ti line emission survey performed by COMPTEL on-board the Compton Gamma-Ray Observatory (CGRO).

Iyudin, A F

1999-01-01

387

Nuclear lines revealing the injection of cosmic rays in supernova remnants  

CERN Multimedia

At high energies, the hadronic origin of gamma rays from supernova remnants is still debated. Assuming the observed gamma-rays from the Wolf-Rayet supernova remnant Cas A are due to accelerated protons and ions, we predict the nuclear de-excitation line emission arising from interactions with the heavy elements in the supernova ejecta. This illustrative example highlights the importance of MeV gamma ray observations of the hadronic fingerprint of cosmic rays. The lines could be observed in the MeV band with a future space mission such as GRIPS which has been proposed to ESA as an all-sky survey mission with gamma-ray, X-ray and near-infrared telescopes. In MeV gamma rays, its sensitivity will improve by a factor of 40 compared with previous missions.

Tibolla, O; Summa, A; Paravac, A; Greiner, J; Kanbach, G

2011-01-01

388

Suzaku Results of SN 1006: Chemical Abundances of the ''youngest'' Galactic Type Ia Supernova Remnant  

International Nuclear Information System (INIS)

SN 1006 is one of the supernova remnants (SNR) recorded in the Japanese diary 'Meigetsuki'. From the historical records including Meigetsuki, we conclude that SN 1006 was the brightest type Ia supernova remnant. We report on the observations of SN 1006 with the X-ray Imaging Spectrometers (XIS) on board the 5-th Japanese X-ray satellite Suzaku. We found that the ionization age of SN 1006 is the youngest among any Galactic SNRs, hence is the best SNR to study early phase of type Ia. In the X-ray spectrum, we found the K-shell emission lines from heavy elements, in particular that from iron, for the first time. The X-ray emitting plasma is highly overabundant in heavy elements, hence are likely due to ejecta. The abundance pattern agrees well to the theoretical prediction of type Ia supernova.

2008-05-21

389

X-ray emission from supernova remnants with particular reference to the Cygnus Loop  

International Nuclear Information System (INIS)

Observational or theoretical results related to the study of supernova remnants (SNRs) are described. Some background information is given by reviewing the present status of our knowledge of supernovae and supernova remnants, both from theory and observations. Also the distribution of all known radio, optical, and X-ray SNRs in the Galaxy is shown and a comparison is made. The X-ray observations of the well-known X-ray SNR the Cygnus Loop are discussed in detail and the discovery of a new X-ray emitting SNR W44 is described. Other radio sources are investigated, and the observed X-ray emission of SNRs are analysed using thermal spectra like exponential or bremsstrahlung spectra. The X-ray line spectrum that emerges from SNRs is described in detail. (Auth.)

1979-01-01

390

FORMATION AND EVOLUTION OF DUST IN TYPE IIb SUPERNOVAE WITH APPLICATION TO THE CASSIOPEIA A SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

The amount and size of dust formed in the ejecta of core-collapse supernovae (CCSNe) and injected into the interstellar medium (ISM) depend on the type of CCSNe through the varying thicknesses of their outer envelopes. Recently Cas A was identified as a Type IIb SN (SN IIb) that is characterized by a small-mass hydrogen envelope. In order to clarify how the amount of dust formed in the ejecta and supplied into the ISM depends on the type of CCSNe, we investigate the formation of dust grains in the ejecta of an SN IIb and their evolution in the shocked gas in the SN remnant (SNR) by considering two sets of density structures (uniform and power-law profiles) for the circumstellar medium (CSM). Based on these calculations, we also simulate the time evolution of thermal emission from the shock-heated dust in the SNR and compare the results with the observations of Cas A SNR. We find that the total mass of dust formed in the ejecta of an SN IIb is as large as 0.167 Msun but the average radius of dust is smaller than 0.01 ?m and is significantly different from those in SNe II-P with massive hydrogen envelopes; in the explosion with the small-mass hydrogen envelope, the expanding He core undergoes little deceleration, so that the gas density in the He core is too low for large-sized grains to form. In addition, the low-mass hydrogen envelope of the SN IIb leads to the early arrival of the reverse shock at the dust-forming region. If the CSM is more or less spherical, then the newly formed small grains would be completely destroyed in the relatively dense shocked gas for the CSM hydrogen density of nH>0.1 cm-3 without being injected into the ISM. However, the actual CSM is likely to be non-spherical, so a portion of the dust grains could be ejected into the ISM without being shocked. We demonstrate that the temporal evolution of the spectral energy distribution (SED) by thermal emission from dust is sensitive to the ambient gas density and structure that affects the passage of the reverse shock into the ejecta. Thus, the SED evolution reflects the evolution of dust through erosion by sputtering and stochastic heating. For Cas A, we consider the CSM produced by the steady mass loss of M-dot?8x10-5 Msun yr-1 during the supergiant phase. Then we find that the observed infrared SED of Cas A is reasonably reproduced by thermal emission from the newly formed dust of 0.08 Msun, which consists of the 0.008 Msun shock-heated warm dust and 0.072 Msun unshocked cold dust.

2010-04-10

391

The Chandra ACIS Survey of M33: X-ray, Optical and Radio Properties of the Supernova Remnants  

CERN Document Server

M33 contains a large number of emission nebulae identified as supernova remnants (SNRs) based on the high [S II]:Ha ratios characteristic of shocked gas. Using Chandra data from the ChASeM33 survey with a 0.35-2 keV sensitivity of about 2 x 10**34 ergs/s, we have detected 82 of 137 SNR candidates, yielding confirmation of (or at least strongly support for) their SNR identifications. This provides the largest sample of remnants detected at optical and X-ray wavelengths in any galaxy, including the Milky Way. A spectral analysis of the seven X-ray brightest SNRs reveals that two, G98-31 and G98-35, have spectra that appear to indicate enrichment by ejecta from core-collapse supernova explosions. In general, the X-ray detected SNRs have soft X-ray spectra compared to the vast majority of sources detected along the line of sight to M33. It is unlikely that there are any other undiscovered thermally dominated X-ray SNRs with luminosities in excess of about 4 x 10**35 ergs/s in the portions of M33 covered by the Ch...

Long, Knox S; Winkler, P Frank; Becker, Robert H; Gaetz, Terrance J; Ghavamian, Parviz; Helfand, David J; Hughes, John P; Kirshner, Robert P; Kuntz, Kip D; McNeil, Emily K; Pannuti, Thomas G; Plucinsky, Paul P; Saul, Destry; Tuellmann, Ralph; Williams, Benjamin

2010-01-01

392

Infrared and X-Ray Spectroscopy of the Kes 75 Supernova Remnant Shell: Characterizing the Dust and Gas Properties  

CERN Multimedia

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modeled by either a single thermal component with a temperature of ~ 1.5 keV, or with two thermal components with temperatures of 1.5 and 0.2 keV. Previous studies suggest that the hot component may originate from reverse-shocked SN ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from supernova (SN) ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favoring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and IR emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the ...

Temim, Tea; Arendt, Richard G; Dwek, Eli

2011-01-01

393

Resonant neutrino spin-flavor precession and supernova shock revival  

International Nuclear Information System (INIS)

A new mechanism of supernova shock revival is proposed which involves the resonant spin-flavor precession of neutrinos with a transition magnetic moment in the magnetic field of the supernova. The mechanism can be operative in supernovae for transition magnetic moments as small as 10-14?B provided the neutrino mass squared difference is in the range ?m2?(3 eV)2-(600eV)2. It is shown that this mechanism can increase the neutrino-induced shock reheating energy by about 60%. copyright 1997 The American Physical Society.

1997-01-01

394

A High-Resolution Radio Survey of the VELA Supernova Remnant  

Science.gov (United States)

This paper presents a high-resolution radio continuum (843 MHz) survey of the Vela supernova remnant. The contrast between the structures in the central pulsar-powered nebula of the remnant and the synchrotron radiation shell allows the remnant to be identified morphologically as a member of the composite class. The data are the first of a composite remnant at spatial scales comparable with those available for the Cygnus Loop and the Crab Nebula, and make possible a comparison of radio, optical, and soft X-ray emission from the resolved shell filaments. The survey, made with the Molonglo Observatory Synthesis Telescope, covers an area of 50 deg^2 at a resolution of 43" x 60", while imaging structures on scales up to 30'.

Bock, D. C.-J.; Turtle, A. J.; Green, A. J.

1998-10-01

395

A Chandra ACIS view of the Thermal Composite Supernova Remnant 3C391  

CERN Document Server

We present a 60 ks Chandra ACIS-S observation of the thermal composite supernova remnant 3C391. The southeast-northwest elongated morphology is similar to that previously found in radio and X-ray studies. This observation unveils a highly clumpy structure of the remnant. Detailed spatially resolved spectral analysis for the small-scale features reveals that the interior gas is generally of normal metal abundance and has approached or basically reached ionization equilibrium. The hydrogen column density increases from southeast to northwest. Three mechanisms, radiative rim, thermal conduction, and cloudlet evaporation, may all play roles in the X-ray appearance of 3C391 as a "thermal composite" remnant, but there are difficulties with each of them in explaining some physical properties. Comparatively, the cloudlet evaporation model is favored by the main characteristics such as the highly clumpy structure and the uniform temperature and density distribution over most of the remnant. The directly measured posts...

Chen, Y; Slane, P O; Wang, Q D; Chen, Yang; Su, Yang; Slane, Patrick O.

2004-01-01

396

On the Amplification of Magnetic Field by a Supernova Blast Shock Wave in a Turbulent Medium  

Science.gov (United States)

We have performed extensive two-dimensional magnetohydrodynamic simulations to study the amplification of magnetic fields when a supernova blast wave propagates into a turbulent interstellar plasma. The blast wave is driven by injecting high pressure in the simulation domain. The interstellar magnetic field can be amplified by two different processes, occurring in different regions. One is facilitated by the fluid vorticity generated by the "rippled" shock front interacting with the background turbulence. The resulting turbulent flow keeps amplifying the magnetic field, consistent with earlier work. The other process is facilitated by the growth of the Rayleigh-Taylor instability at the contact discontinuity between the ejecta and the shocked medium. This can efficiently amplify the magnetic field and tends to produce the highest magnetic field. We investigate the dependence of the amplification on numerical parameters such as grid-cell size and on various physical parameters. We show that the magnetic field has a characteristic radial profile such that the downstream magnetic field gets progressively stronger away from the shock. This is because the downstream magnetic field needs a finite time to reach the efficient amplification, and will get further amplified in the Rayleigh-Taylor region. In our simulation, we do not observe a systematic strong magnetic field within a small distance to the shock. This indicates that if the magnetic-field amplification in supernova remnants indeed occurs near the shock front, other processes such as three-dimensional instabilities, plasma kinetics, and/or cosmic ray effect may need to be considered to explain the strong magnetic field in supernova remnants.

Guo, Fan; Li, Shengtai; Li, Hui; Giacalone, Joe; Jokipii, J. R.; Li, David

2012-03-01

397

ON THE AMPLIFICATION OF MAGNETIC FIELD BY A SUPERNOVA BLAST SHOCK WAVE IN A TURBULENT MEDIUM  

Energy Technology Data Exchange (ETDEWEB)

We have performed extensive two-dimensional magnetohydrodynamic simulations to study the amplification of magnetic fields when a supernova blast wave propagates into a turbulent interstellar plasma. The blast wave is driven by injecting high pressure in the simulation domain. The interstellar magnetic field can be amplified by two different processes, occurring in different regions. One is facilitated by the fluid vorticity generated by the 'rippled' shock front interacting with the background turbulence. The resulting turbulent flow keeps amplifying the magnetic field, consistent with earlier work. The other process is facilitated by the growth of the Rayleigh-Taylor instability at the contact discontinuity between the ejecta and the shocked medium. This can efficiently amplify the magnetic field and tends to produce the highest magnetic field. We investigate the dependence of the amplification on numerical parameters such as grid-cell size and on various physical parameters. We show that the magnetic field has a characteristic radial profile such that the downstream magnetic field gets progressively stronger away from the shock. This is because the downstream magnetic field needs a finite time to reach the efficient amplification, and will get further amplified in the Rayleigh-Taylor region. In our simulation, we do not observe a systematic strong magnetic field within a small distance to the shock. This indicates that if the magnetic-field amplification in supernova remnants indeed occurs near the shock front, other processes such as three-dimensional instabilities, plasma kinetics, and/or cosmic ray effect may need to be considered to explain the strong magnetic field in supernova remnants.

Guo Fan; Li Shengtai; Li Hui; Li, David [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Giacalone, Joe; Jokipii, J. R. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 (United States)

2012-03-10

398

The complex relations between Supernova Remnants and Neutron Stars  

Directory of Open Access Journals (Sweden)

Full Text Available Se espera que la mayor a de las supernovas (SN) produzca una estrella de neutrones (EN) observable como pulsar en ondas de radio. Las observaciones, sin embargo, muestran escasas coincidencias entre restos de supernovas (RSN) y EN. Se presenta una puesta al d a de resultados de observaciones multiespectrales llevadas a cabo para investigar este aspecto. El trabajo se focaliza en la comprensi on actual de las nebulosas de viento de pulsares, as como en las diferentes formas en que puede manifestarse una estrella de neutrones, tales como pulsares an omalos en rayos X, estrellas de neutrones radio-quietas y repetidores en rayos blandos.

G. Dubner

2002-01-01

399

A search for OH 6 GHz maser emission towards supernova remnants  

CERN Multimedia

OH masers at 1720 MHz have proven to be excellent indicators of interactions between supernova remnants and molecular clouds. OH excitation calculations suggest that the 6049 MHz OH maser line is excited for higher column densities than for the 1720 MHz line. Previous observations and modelling of 1612, 1665 and 1667 MHz OH absorption and 1720 MHz OH masers indicated that the column densities in some supernova remnants, ~10e17 cm^-2, may be high enough for 6049 MHz OH masers to exist. It is therefore a potentially valuable indicator of remnant-cloud interaction. We present excitation calculations predicting the formation of 6049 MHz OH masers and results of a survey using the Parkes Methanol Multibeam receiver for 6049, 6035 and 6030 MHz OH masers towards 35 supernova remnants, a star-forming region and 4 fields in the Large and Small Magellanic Clouds. Two new sites of 6035 and 6030 MHz OH maser emission associated with star-forming regions have been discovered. No 6049 MHz masers were detected to a brightne...

McDonnell, Korinne E; Vaughan, Alan E

2008-01-01

400

The Fast and the Furious: Energetic Phenomena in Isolated Neutron Stars, Pulsar Wind Nebulae and Supernova Remnants  

Science.gov (United States)

Online Presentations of 'The Fast and the Furious: Energetic Phenomena in Isolated Neutron Stars, Pulsar Wind Nebulae and Supernova Remnants', a workshop organized by the XMM-Newton Science Operations Centre of the European Space Agency (ESA)

Ness, J.-U.

2013-07-01

 
 
 
 
401

Tools for Dissecting Supernova Remnants Observed with Chandra: Methods and Application to the Galactic Remnant W49B  

CERN Multimedia

We introduce methods to quantify the X-ray morphologies of supernova remnants observed with the Chandra X-ray Telescope. These include a power-ratio technique to measure morphological asymmetries, correlation-length analysis to probe chemical segregation and distribution, and wavelet-transform analysis to quantify X-ray substructure. We demonstrate the utility and accuracy of these techniques on relevant synthetic data. Additionally, we show the methods' capabilities by applying them to the 55-ks Chandra ACIS observation of the galactic supernova remnant W49B. We analyze the images of prominent emission lines in W49B and use the results to discern physical properties. We find that the iron morphology is very distinct from the other elements: it is statistically more asymmetric, more segregated, and has 25% larger emitting substructures than the lighter ions. Comparatively, the silicon, sulfur, argon, and calcium are well-mixed, more isotropic, and have smaller, equally-sized emitting substructures. Based on f...

Lopez, Laura A; Pooley, David A; Jeltema, Tesla E

2008-01-01

402

The hydrodynamics of the supernova remnant Cas A: The influence of the progenitor evolution on the velocity structure and clumping  

CERN Multimedia

There are large differences in the proposed progenitor models for the Cas A SNR. One of these differences is the presence or absence of a Wolf-Rayet (WR) phase of the progenitor star. The mass loss history of the progenitor star strongly affects the shape of the Supernova remnant (SNR). In this paper we investigate whether the progenitor star of Cas A had a WR phase or not and how long it may have lasted. We performed two-dimensional multi-species hydrodynamical simulations of the CSM around the progenitor star for several WR life times, each followed by the interaction of the supernova ejecta with the CSM. We then looked at the influence of the length of the WR phase and compared the results of the simulations with the observations of Cas A. The difference in the structure of the CSM, for models with different WR life times, has a strong impact on the resulting SNR. With an increasing WR life time the reverse shock velocity of the SNR decreases and the range of observed velocities in the shocked material inc...

van Veelen, B; Vink, J; García-Segura, G; van Marle, A J

2009-01-01

403

The Progenitor of the New COMPTEL/ROSAT Supernova Remnant in Vela  

CERN Multimedia

We propose that (1) the newly discovered supernova remnant (SNR), GRO J0852--4642/RX J0852.0--4622, was probably created by a core-collapse supernova of a massive star, and (2) the same supernova event which produced the $^{44}$Ti detected by COMPTEL from this source is probably also responsible for a large fraction of the observed $^{26}$Al emission in the Vela region detected by the same instrument. We show that the remnant is currently expanding too slowly for its young age to be due to a Type Ia supernova (SNIa). Even for a massive star progenitor, the SNR is required to be $\\sim250$ pc away in a dense environment at the edge of the Gum nebula. The progenitor has a preferred ejecta mass of $\\le10M_\\odot$ and a large kinetic energy of $\\ge 2\\times 10^{51}$ ergs, and therefore, it is probably a Type Ib or Type Ic supernova. The required high ambient density of $n_H > 300$ cm$^{-3}$, however, has yet to be confirmed by observations. An SNIa progenitor at the same distance may still be possible but it would n...

Chen, W; Chen, Wan

1998-01-01

404

SEARCH FOR GAMMA-RAY EMISSION FROM THE SUPERNOVA REMNANT IC 443 WITH THE MAGIC TELESCOPE  

Directory of Open Access Journals (Sweden)

Full Text Available TeV observations of Supernova remnants (SNRs) and, in particular, of SNRs which appear to be physically related to EGRET sources are a prime target for the MAGIC telescope. MAGIC's spatial resolution and sensi- tivity can probe the main mechanism responsible for producing high energy photons in the SNR neighbourhood. Based on a recent systematical analysis of the molecular environment of the vicinity of all SNR-EGRET source pairs, the IC 443 remnant was chosen for observations with MAGIC. We brie y describe the observational strategy which provided the detection of a new very-high energy gamma-ray source: MAGIC 0616+225.

R. J. Garcu00EDa Lu00F3pez; the MAGIC Collaboration

2009-01-01

405

The soft x-ray spectra of Cassiopeia A and Tycho's supernova remnant  

International Nuclear Information System (INIS)

[en] The x-ray spectra of Tycho's supernova remnant and Cas A have been measured with good statistics. Both spectra show evidence for silicon line emission. The thermal model of Tucker and Koren has been used to fit both spectra. To obtain a satisfactory fit to the data with this model, the silicon abundance must be increased about 10 times from the usual cosmic abundance values. Neither spectrum can be fitted with exponential or power-law models without the addition of line emission. Tycho's remnant shows very little soft X-ray absorption

1975-08-15

406

Gamma-ray emission from the shell of supernova remnant W44 revealed by the Fermi LAT.  

Science.gov (United States)

Recent observations of supernova remnants (SNRs) hint that they accelerate cosmic rays to energies close to ~10(15) electron volts. However, the nature of the particles that produce the emission remains ambiguous. We report observations of SNR W44 with the Fermi Large Area Telescope at energies between 2 x 10(8) electron volts and 3 x10(11) electron volts. The detection of a source with a morphology corresponding to the SNR shell implies that the emission is produced by particles accelerated there. The gamma-ray spectrum is well modeled with emission from protons and nuclei. Its steepening above approximately 10(9) electron volts provides a probe with which to study how particle acceleration responds to environmental effects such as shock propagation in dense clouds and how accelerated particles are released into interstellar space. PMID:20056857

Abdo, A A; Ackermann, M; Ajello, M; Baldini, L; Ballet, J; Barbiellini, G; Baring, M G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Celik, O; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cognard, I; Cohen-Tanugi, J; Cominsky, L R; Conrad, J; Cutini, S; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Espinoza, C; Farnier, C; Favuzzi, C; Fegan, S J; Focke, W B; Fortin, P; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giavitto, G; Giebels, B; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hughes, R E; Jackson, M S; Jóhannesson, G; Johnson, A S; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Katsuta, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kramer, M; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Lyne, A G; Madejski, G M; Makeev, A; Mazziotta, M N; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Nolan, P L; Norris, J P; Noutsos, A; Nuss, E; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Rochester, L S; Rodriguez, A Y; Romani, R W; Roth, M; Ryde, F; Sadrozinski, H F-W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Stappers, B W; Stecker, F W; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thayer, J G; Theureau, G; Thompson, D J; Tibaldo, L; Tibolla, O; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Venter, C; Vilchez, N; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Yamazaki, R; Ylinen, T; Ziegler, M

2010-01-07

407

Discovery of Radio/X-ray/Optical Resolved Supernova Remnants in the Center of the Andromeda Galaxy  

CERN Multimedia

We have detected a spatially resolved supernova remnant (SNR) in the center of the Andromeda Galaxy, in radio, X-ray, and optical wavelengths. These observations provide the highest spatial resolution imaging of a radio/X-ray/optical SNR in that galaxy to date. The multi-wavelength morphology, radio spectral index, X-ray colors, and narrow-band optical imaging are consistent with a shell-type SNR. A second SNR is also seen resolved in both radio and X-ray. By comparing the morphological sturcture of the SNRs in different wavelengths and with that in our own Galaxy, we can study the shock morphologies of SNRs in the Andromeda Galaxy. The proximity of the SNRs to the core suggests high interstellar medium density in the vicinity of the SNRs in the center of the Andromeda Galaxy.

Kong, A K H; Williams, B F; García, M R; Dickel, J R

2003-01-01

408

Gamma-ray emission from the shell of supernova remnant W44 revealed by the Fermi LAT.  

UK PubMed Central (United Kingdom)

Recent observations of supernova remnants (SNRs) hint that they accelerate cosmic rays to energies close to ~10(15) electron volts. However, the nature of the particles that produce the emission remains ambiguous. We report observations of SNR W44 with the Fermi Large Area Telescope at energies between 2 x 10(8) electron volts and 3 x10(11) electron volts. The detection of a source with a morphology corresponding to the SNR shell implies that the emission is produced by particles accelerated there. The gamma-ray spectrum is well modeled with emission from protons and nuclei. Its steepening above approximately 10(9) electron volts provides a probe with which to study how particle acceleration responds to environmental effects such as shock propagation in dense clouds and how accelerated particles are released into interstellar space.

Abdo AA; Ackermann M; Ajello M; Baldini L; Ballet J; Barbiellini G; Baring MG; Bastieri D; Baughman BM; Bechtol K; Bellazzini R; Berenji B; Blandford RD; Bloom ED; Bonamente E; Borgland AW; Bregeon J; Brez A; Brigida M; Bruel P; Burnett TH; Buson S; Caliandro GA; Cameron RA; Caraveo PA; Casandjian JM; Cecchi C; Celik O; Chekhtman A; Cheung CC; Chiang J; Ciprini S; Claus R; Cognard I; Cohen-Tanugi J; Cominsky LR; Conrad J; Cutini S; Dermer CD; de Angelis A; de Palma F; Digel SW; do Couto e Silva E; Drell PS; Dubois R; Dumora D; Espinoza C; Farnier C; Favuzzi C; Fegan SJ; Focke WB; Fortin P; Frailis M; Fukazawa Y; Funk S; Fusco P; Gargano F; Gasparrini D; Gehrels N; Germani S; Giavitto G; Giebels B; Giglietto N; Giordano F; Glanzman T; Godfrey G; Grenier IA; Grond