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1

Particle acceleration by shocks in supernova remnants  

CERN Document Server

Particle acceleration occurs on a range of scales from AU in the heliosphere to Mpc in clusters of galaxies and to energies ranging from MeV to EeV. A number of acceleration processes have been proposed, but diffusive shock acceleration (DSA) is widely invoked as the predominant mechanism. DSA operates on all these scales and probably to the highest energies. DSA is simple, robust and predicts a universal spectrum. However there are still many unknowns regarding particle acceleration. This paper focuses on the particular question of whether supernova remnants (SNR) can produce the Galactic CR spectrum up to the knee at a few PeV. The answer depends in large part on the detailed physics of diffusive shock acceleration.

Bell, A R

2013-01-01

2

Grain Destruction in a Supernova Remnant Shock Wave  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 profile...

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

2013-01-01

3

Shocks and Particle Acceleration in Supernova Remnants: Observational Features  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The last ten years a number of observational advances have substantially increased our knowledge of shock phenomena in supernova remnants. This progress has mainly been made possible by the recent improvements in X-ray and Gamma-ray instrumentation. It has become clear that some shell-type supernova remnants, e.g. SN 1006, have X-ray emission dominated by synchrotron radiation, proving that electrons are accelerated up to 100 TeV. This is still an order of magnitude below 3E...

Vink, Jacco

2003-01-01

4

Supernova remnant shocks in an inhomogenous interstellar medium  

International Nuclear Information System (INIS)

This paper discusses how the inhomogeneity of the interstellar medium (ISM) has a profound effect on the propagation of the interstellar shock generated by a supernova and on the appearance of the resulting supernova remnant (SNR). Low mass supernovae produce remnants that interact with the pristine ISM, which has density inhomogeneities (clouds) on a wide range of scales. The shock compresses and accelerates the clouds it encounters; inside the blast wave, the clouds are hydrodynamically unstable, and mass is injected from the clouds into the intercloud medium. Embedded clouds interact thermally with the shock also, adding mass to the hot intercloud medium via thermal evaporation or subtracting it via condensation and thermal instability. Mass injection into the hot intercloud medium, whether dynamical or thermal, leads to infrared emission as dust mixes with the hot gas and is thermally sputtered. The remnants of massive supernovae interact primarily with circumstellar matter and with interstellar material which has been processed by the ionizing radiation and wind of the progenitor star

1987-06-08

5

Collisionless shock and supernova remnant simulations on VULCAN  

Science.gov (United States)

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.

Woolsey, N. C.; Ali, Y. Abou; Evans, R. G.; Grundy, R. A. D.; Pestehe, S. J.; Carolan, P. G.; Conway, N. J.; Dendy, R. O.; Helander, P.; McClements, K. G.; Kirk, J. G.; Norreys, P. A.; Notley, M. M.; Rose, S. J.

2001-05-01

6

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

2001-05-01

7

Grain Destruction in a Supernova Remnant Shock Wave  

CERN Document Server

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

8

Cosmic ray acceleration at perpendicular shocks in supernova remnants  

CERN Document Server

Supernova remnants (SNRs) are believed to accelerate particles up to high energies through the mechanism of diffusive shock acceleration (DSA). Except for direct plasma simulations, all modeling efforts must rely on a given form of the diffusion coefficient, a key parameter that embodies the interactions of energetic charged particles with the magnetic turbulence. The so-called Bohm limit is commonly employed. In this paper we revisit the question of acceleration at perpendicular shocks, by employing a realistic model of perpendicular diffusion. Our coefficient reduces to a power-law in momentum for low momenta (of index $\\alpha$), but becomes independent of the particle momentum at high momenta (reaching a constant value $\\kappa_{\\infty}$ above some characteristic momentum $p_{\\rm c}$). We first provide simple analytical expressions of the maximum momentum that can be reached at a given time with this coefficient. Then we perform time-dependent numerical simulations to investigate the shape of the particle d...

Ferrand, Gilles; Shalchi, Andreas; Safi-Harb, Samar; Edmon, Paul; Mendygral, Peter

2014-01-01

9

ICPP: Collisionless shock and supernova remnant simulation experiments on VULCAN.  

Science.gov (United States)

The VULCAN laser at the Central Laser Facility is used for laboratory-based simulations of collisionless shocks. One of the most difficult aspects of collisionless shock behaviour, the role of the magnetic field, is to be tested directly against experiment. Preliminary experiments to generate strong magnetic fields using a laser-driven mm-scale Helmholtz coil, and the formation of collisionless colliding plasmas using two counter-streaming exploding foil plasmas will be discussed. We consider the scaling of the hydrodynamics and magnetic field of the these experiments to those in supernova remnants (SNR) impacting the interstellar medium (ISM). This is achieved by ensuring the experiment and the SNR-ISM exhibit similar values of key dimensionless parameters. Work supported in part by EPSRC, CLF Direct Access, CEC-ERB FMR XCT 980168, Euratom and the UK DTI.

Woolsey, Nigel C.

2000-10-01

10

Dust sputtering by Reverse Shocks in Supernova Remnants  

CERN Document Server

We consider sputtering of dust grains, believed to be formed in cooling supernovae ejecta, under the influence of reverse shocks. In the regime of self-similar evolution of reverse shocks, we can follow the evolution of ejecta density and temperature analytically as a function of time in different parts of the ejecta, and calculate the sputtering rate of graphite and silicate grains embedded in the ejecta as they encounter the reverse shock. Through analytic (1D) calculations, we find that a fraction of dust mass ($ 1\\hbox{--}20$% for silicates and %$\\le 5$% for graphites) can be sputtered by reverse shocks, the fraction varying with the grain size distribution and the steepness of the density profile of the ejecta mass. It is expected that many more grains will get sputtered in the region between the forward and reverse shocks, so that our analytical results provide a lower limit to the destroyed fraction of dust mass.

nath, Biman B; Shull, J Michael

2008-01-01

11

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

Science.gov (United States)

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.

Drake, R. P.

2002-02-01

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

2002-02-01

13

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

CERN Multimedia

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

14

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

International Nuclear Information System (INIS)

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

15

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

16

Chandra Observations of Shock Kinematics in Supernova Remnant 1987A  

CERN Document Server

We report the first results from deep X-ray observations of the SNR 1987A with the Chandra LETG. Temperatures inferred from line ratios range from 0.1 - 2 keV and increase with ionization potential. Expansion velocities inferred from X-ray line profiles range from 300 - 1700 km/s, much less than the velocities inferred from the radial expansion of the radio and X-ray images. We can account for these observations with a scenario in which the X-rays are emitted by shocks produced where the supernova blast wave strikes dense protrusions of the inner circumstellar ring, which are also responsible for the optical hot spots.

Zhekov, S A; Borkowski, K J; Burrows, D N; Park, S

2005-01-01

17

Electron Heating, Magnetic Field Amplification, and Cosmic-Ray Precursor Length at Supernova Remnant Shocks  

Science.gov (United States)

We investigate the observability, by direct and indirect means, of a shock precursor arising from magnetic field amplification by cosmic rays. We estimate the depth of such a precursor under conditions of nonresonant amplification, which can provide magnetic field strengths comparable to those inferred for supernova remnants. Magnetic field generation occurs as the streaming cosmic rays induce a plasma return current, and it may be quenched by either nonresonant or resonant channels. In the case of nonresonant saturation, the cosmic rays become magnetized and amplification saturates at higher magnetic fields. The precursor can extend out to 1017-1018 cm and is potentially detectable. If resonant saturation occurs, the cosmic rays are scattered by turbulence and the precursor length will likely be much smaller. The dependence of precursor length on shock velocity has implications for electron heating. In the case of resonant saturation, this dependence is similar to that in the more familiar resonantly generated shock precursor, which when expressed in terms of the cosmic-ray diffusion coefficient kappav and shock velocity vs is kappav/vs . In the nonresonantly saturated case, the precursor length declines less quickly with increasing vs . Where precursor length proportional to 1/vs gives constant electron heating, this increased precursor length could be expected to lead to higher electron temperatures for nonresonant amplification. This should be expected at faster supernova remnant shocks than studied by previous works. Existing results and new data analysis of SN 1006 and Cas A suggest some observational support for this idea.

Laming, J. Martin; Hwang, Una; Ghavamian, Parviz; Rakowski, Cara

2014-07-01

18

Supernova Remnant SNR 0509 lithograph  

Science.gov (United States)

This Hubble Space Telescope image shows what appears to be a delicate bubble of gas floating serenely 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. In the accompanying educational activity, In Search of ... Supernova Remnants, students investigate supernova explosions and remnants through a level 1 inquiry activity using the images and text from the lithograph and other resources. A level 1 inquiry activity can help prepare students to become independent thinkers.

19

$\\gamma$-Rays from Supernova Remnants and the Signatures of Diffusive Shock Acceleration  

CERN Document Server

While the definitive detection of gamma-rays from known supernova remnants (SNRs) remains elusive, the collection of unidentified EGRET sources that may be associated with SNRs has motivated recent modelling of TeV emission from these sources. Current theoretical models use power-law shock-accelerated protons and electrons in their predictions of expected gamma-ray TeV fluxes from those unidentified EGRET sources with remnant associations. In this paper, we explore a more detailed non-linear shock acceleration model, which generates non-thermal proton distributions and includes a self-consistent determination of shock hydrodynamics. We obtain gamma-ray spectra for SNRs allowing for the cessation of acceleration to high energies that is due to the finite ages and sizes of remnants. Gamma-ray spectral cutoffs can be observed in the TeV range for reasonable remnant parameters, and deviations from power-law behaviour are found at all energies ranging from 1 MeV up to the cutoff. Correlated observations by INTEGRA...

Baring, M G; Grenier, I; Baring, Matthew G.; Ellison, Donald C.; Grenier, Isabelle

1997-01-01

20

Observational Evidence of Cosmic-Ray Modified Shocks in Supernova Remnants  

Science.gov (United States)

The results of theoretical and observational studies suggest that, immediately downstream of the forward shock, a significant fraction of the energy density in young, shell-type supernova remnants is in the form of nonthermal particles. The pressure of the nonthermal particles modifies the structure of a shock. There are at least three potentially observable consequences: (1) The temperature of the thermal particles in the shock-heated gas is reduced. (2) The effective compression ratio of the shock is increased. (3) The spectrum of the nonthermal particles flattens with increasing energy. We describe some of the results for each of these three effects and discuss the implications for cosmic-ray acceleration. GEA is supported by the contract SV3-73016 between MIT and the Smithsonian Astrophysical Observatory. The Chandra X-Ray Center at the Smithsonian Astrophysical Observatory is operated on behalf of NASA under the contract NAS8-03060.

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

2008-03-01

 
 
 
 
21

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

International Nuclear Information System (INIS)

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

Bipolar supernova remnants and the obliquity dependence of shock acceleration  

International Nuclear Information System (INIS)

The diffusive shock acceleration mechanism proposed to explain the bipolarity observed in the synchrotron radio emission of young adiabatically expanding shell SNRs is investigated by means of numerical simulations. The theoretical basis of the SNR models and the numerical computation methods are explained, and the results are presented in graphs and synthetic radio maps and discussed in detail. It is found that the efficiency of the acceleration process depends on the obliquity angle theta(Bn) between the shock normal and the uniform magnetic field: models with theta(Bn) of about 90 deg can reproduce the observed azimuthal intensity ratios in most cases, but models with theta(Bn) near 0 deg cannot. 32 refs

1990-01-01

24

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

25

Effects of Neutral Hydrogen on Cosmic-ray Precursors in Supernova Remnant Shock Waves  

Science.gov (United States)

Many fast supernova remnant shocks show spectra dominated by Balmer lines. The H? profiles have a narrow component explained by direct excitations and a thermally Doppler broadened component due to atoms that undergo charge exchange in the post-shock region. However, the standard model does not take into account the cosmic-ray shock precursor, which compresses and accelerates plasma ahead of the shock. In strong precursors with sufficiently high densities, the processes of charge exchange, excitation, and ionization will affect the widths of both narrow and broad line components. Moreover, the difference in velocity between the neutrals and the precursor plasma gives rise to frictional heating due to charge exchange and ionization in the precursor. In extreme cases, all neutrals can be ionized by the precursor. In this Letter we compute the ion and electron heating for a wide range of shock parameters, along with the velocity distribution of the neutrals that reach the shock. Our calculations predict very large narrow component widths for some shocks with efficient acceleration, along with changes in the broad-to-narrow intensity ratio used as a diagnostic for the electron-ion temperature ratio. Balmer lines may therefore provide a unique diagnostic of precursor properties. We show that heating by neutrals in the precursor can account for the observed H? narrow component widths and that the acceleration efficiency is modest in most Balmer line shocks observed thus far.

Raymond, John C.; Vink, J.; Helder, E. A.; de Laat, A.

2011-04-01

26

Diffusive Shock Acceleration of Electrons and Radio Emission from Large Diameter Shell-Type Supernova Remnants  

CERN Multimedia

In present study I examine the capability of diffusive shock acceleration mechanism to explain existing data on radio emission from evolved large diameter shell-type adiabatic supernova remnants (SNRs). Time-dependent ''onion-shell'' model for the radio emission of SNRs is developed, which is based on the assumptions: a) acceleration takes place from thermal energies and test-particle approximation is valid; b) the problem of injection is avoided by introducing, like Bell (1978), two injection parameters; c) to take into consideration very late stages of SNR evolution the analytic approximation of Cox and Andersen (1982) for the shell structure is used; c)no radiative cooling. Constructed Surface Brightness - Diameter $(\\Sigma -D)$ tracks are compared with the empirical $\\Sigma -D$ diagram. The main conclusion of the study is that the DSA mechanism is capable of explaining all the statistics of radio SNRs including very large diameter remnants and giant galactic loops.

Asvarov, A I

2000-01-01

27

Balmer line diagnostic of electron heating at collisionless shocks in supernova remnants  

International Nuclear Information System (INIS)

The mechanism and extent of electron heating at collisionless shocks has recently been under intense investigation. H? Balmer line emission is excited immediately behind the shock front and provides the best diagnostic for the electron to proton temperature ratio at supernova remnant shocks. Two components of emission are produced, a narrow component from electron and proton impact excitation of cold neutrals, and a broad component produced through charge exchange between the cold neutrals and the shock heated protons. Thus the broad and narrow component fluxes reflect the competition between electron and proton impact ionization, electron and proton impact excitation and charge exchange. This diagnostic has led to the discovery of an approximate inverse square relationship between the electron to proton temperature ratio and the shock velocity. In turn, this implies a constant level of electron heating, independent of shock speed above ? 450 km/s. In this talk I will present the observational evidence to date. Time permitting, I will introduce how lower-hybrid waves in an extended cosmic ray precursor could explain such a relationship, and how this and other parameters in the H? profile might relate to properties of cosmic rays and magnetic field amplification ahead of the shock. (author)

2008-10-05

28

Shock and Awe: Measuring the Expansion of the Shock Front of Supernova Remnant SN1006  

Science.gov (United States)

We have determined the expansion of the supernova remnant (SNR) of SN1006 over a seven-year period, using data collected in 2003 and 2010. The data was calibrated and imaged using Miriad and CASA programming before we stacked the two images to accurately assess the expansion rate. Our data was collected from the Very Large Array (VLA) in New Mexico and Australian Telescope Compact Array (ATCA). The 2003 epoch observations were conducted at the ATCA and the VLA. The 2010 epoch observations were conducted only at the ATCA. We processed the data using the Miriad and CASA software packages, which allowed us to perform calibration and imaging of radio interferometer visibility data. We deconvolved the raw images using CLEAN and MAXEN (maximum entropy deconvolution) to remove spurious side lobes, resulting in epoch images with a synthesized beamwidth of 6.0 arcseconds per beam. We used the 2010 image as a template to align the 2003 image and to match resolution. A difference image formed from the two epoch images reveals an obvious expansion of the SNR. We measured the expansion rate at nine points along the shell of the remnant. We found that the expansion rate varied across the remnant’s shell. The greatest amount of expansion measured was 5.71 arcseconds over seven years, which for a distance of 2.2 kpc, has the remnant moving at 8,500 km/s. The average expansion measured across the shell was 4.25 arcseconds over seven years.

Dills, Sidney; McKinney, L.; Moffett, D. A.; Reynoso, E.

2014-01-01

29

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

30

Electron Heating, Magnetic Field Amplification, and Cosmic Ray Precursor Length at Supernova Remnant Shocks  

CERN Document Server

We investigate the observability, by direct and indirect means, of a shock precursor arising from magnetic field amplification by cosmic rays. We estimate the depth of such a precursor under conditions of nonresonant amplification, which can provide magnetic field strengths comparable to those inferred for supernova remnants. Magnetic field generation occurs as the streaming cosmic rays induce a plasma return current, and may be quenched either by nonresonant or resonant channels. In the case of nonresonant saturation, the cosmic rays become magnetized and amplification saturates at higher magnetic fields. The precursor can extend out to $10^{17} - 10^{18}$ cm and is potentially detectable. If resonant saturation occurs, the cosmic rays are scattered by turbulence and the precursor length will likely be much smaller. The dependence of precursor length on shock velocity has implications for electron heating. In the case of resonant saturation, this dependence is similar to that in the more familiar resonantly ...

Laming, J Martin; Ghavamian, Parviz; Rakowski, Cara

2014-01-01

31

Reverse and Forward Shock X-ray Emission in an Evolutionary Model of Supernova Remnants undergoing Efficient Diffusive Shock Acceleration  

CERN Document Server

We present new models for the forward and reverse shock thermal X-ray emission from core-collapse and Type Ia supernova remnants (SNRs) which include the efficient production of cosmic rays via non-linear diffusive shock acceleration (DSA). Our CR-hydro-NEI code takes into account non-equilibrium ionization (NEI), hydrodynamic effects of efficient CR production on the SNR evolution, and collisional temperature equilibration among heavy ions and electrons in both the shocked supernova (SN) ejecta and the shocked circumstellar material. While X-ray emission is emphasized here, our code self-consistently determines both thermal and non-thermal broadband emission from radio to TeV energies. We include Doppler broadening of the spectral lines by thermal motions of the ions and by the remnant expansion. We study, in general terms, the roles which the ambient environment, progenitor models, temperature equilibration, and processes related to DSA have on the thermal and non-thermal spectra. The study of X-ray line em...

Lee, Shiu-Hang; Ellison, Donald C; Nagataki, Shigehiro; Slane, Patrick O

2014-01-01

32

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

CERN Document Server

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

33

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

34

KINEMATICS OF SHOCKED MOLECULAR GAS ADJACENT TO THE SUPERNOVA REMNANT W44  

International Nuclear Information System (INIS)

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

2013-09-01

35

GALACTIC AND EXTRAGALACTIC SUPERNOVA REMNANTS AS SITES OF PARTICLE ACCELERATION  

Directory of Open Access Journals (Sweden)

Full Text Available Supernova remnants, owing to their strong shock waves, are likely sources of Galactic cosmic rays. Studies of supernova remnants in X-rays and gamma rays provide us with new insights into the acceleration of particles to high energies. This paper reviews the basic physics of supernova remnant shocks and associated particle acceleration and radiation processes. In addition, the study of supernova remnant populations in nearby galaxies and the implications for Galactic cosmic ray distribution are discussed.

Manami Sasaki

2013-12-01

36

Cosmic ray escape from supernova remnants  

CERN Multimedia

Galactic cosmic rays are believed to be accelerated at supernova remnants via diffusive shock acceleration. Though this mechanism gives fairly robust predictions for the spectrum of particles accelerated at the shock, the spectrum of the cosmic rays which are eventually injected in the interstellar medium is more uncertain and depends on the details of the process of particle escape from the shock. Knowing the spectral shape of these escaping particles is of crucial importance in order to assess the validity of the supernova remnant paradigm for cosmic ray origin. Moreover, after escaping from a supernova remnant, cosmic rays interact with the surrounding ambient gas and produce gamma rays in the vicinity of the remnant itself. The detection of this radiation can be used as an indirect proof of the fact that the supernova remnant was indeed accelerating cosmic rays in the past.

Gabici, Stefano

2011-01-01

37

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

Science.gov (United States)

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.

Lee, Shiu-Hang; Ellison, Donald C.; Nagataki, Shigehiro

2012-05-01

38

Pulsar wind nebulae in supernova remnants  

CERN Document Server

A spherically symmetric model is presented for the interaction of a pulsar wind with the associated supernova remnant. This results in a pulsar wind nebula whose evolution is coupled to the evolution of the surrounding supernova remnant. This evolution can be divided in three stages. The first stage is characterised by a supersonic expansion of the pulsar wind nebula into the freely expanding ejecta of the progenitor star. In the next stage the pulsar wind nebula is not steady; the pulsar wind nebula oscillates between contraction and expansion due to interaction with the reverse shock of the supernova remnant: reverberations which propagate forward and backward in the remnant. After the reverberations of the reverse shock have almost completely vanished and the supernova remnant has relaxed to a Sedov solution, the expansion of the pulsar wind nebula proceeds subsonically. In this paper we present results from hydrodynamical simulations of a pulsar wind nebula through all these stages in its evolution. The s...

Van der Swaluw, E; Gallant, Y A; Tóth, G

2000-01-01

39

Thermal X-Ray Emission from Shocked Ejecta in Type Ia Supernova Remnants II: Parameters Affecting the Spectrum  

CERN Document Server

The supernova remnants left behind by Type Ia supernovae provide an excellent opportunity for the study of these enigmatic objects. In a previous work, we showed that it is possible to use the X-ray spectra of young Type Ia supernova remnants to explore the physics of Type Ia supernovae and identify the relevant mechanism underlying these explosions. Our simulation technique is based on hydrodynamic and nonequilibrium ionization calculations of the interaction of a grid of Type Ia explosion models with the surrounding ambient medium, coupled to an X-ray spectral code. In this work we explore the influence of two key parameters on the shape of the X-ray spectrum of the ejecta: the density of the ambient medium around the supernova progenitor and the efficiency of collisionless electron heating at the reverse shock. We also discuss the performance of recent 3D simulations of Type Ia SN explosions in the context of the X-ray spectra of young SNRs. We find a better agreement with the observations for Type Ia supe...

Badenes, C; Bravo, E

2005-01-01

40

SHOCKS, SEYFERTS, AND THE SUPERNOVA REMNANT CONNECTION: A CHANDRA OBSERVATION OF THE CIRCINUS GALAXY  

Energy Technology Data Exchange (ETDEWEB)

We analyze new Chandra observations of the nearest (D = 4 Mpc) Seyfert 2 active galaxy, Circinus, and match them to pre-existing radio, infrared, and optical data to study the kpc-scale emission. The proximity of Circinus allows us to observe in striking detail the structure of the radio lobes, revealing for the first time edge-brightened emission in both X-rays and radio. After considering various other possible scenarios, we show that this extended emission in Circinus is most likely caused by a jet-driven outflow, which is driving shells of strongly shocked gas into the halo of the host galaxy. In this context, we estimate Mach numbers M{approx}2.7-3.6 and M{approx}2.8-5.3 for the W and E shells, respectively. We derive temperatures of 0.74{sup +0.06} {sub -0.05} keV and 0.8-1.8 keV for the W and E shells and an expansion velocity of {approx}900-950 km s{sup -1}. We estimate that the total energy (thermal and kinetic) involved in creating both shells is {approx}2 Multiplication-Sign 10{sup 55} erg, and their age is {approx}10{sup 6} yr. Comparing these results with those we previously obtained for Centaurus A, NGC 3801, and Mrk 6, we show that these parameters scale approximately with the radio power of the parent active galactic nucleus (AGN). The spatial coincidence between the X-ray and edge-brightened radio emission in Circinus resembles the morphology of some supernova remnant shocks. This parallel has been expected for AGNs but has never been observed before. We investigate what underlying mechanisms both types of systems may have in common, arguing that, in Circinus, the edge-brightening in the shells may be accounted for by a B field enhancement caused by shock compression but do not preclude some local particle acceleration. These results can be extrapolated to other low-power systems, particularly those with late-type hosts.

Mingo, B.; Hardcastle, M. J. [School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Croston, J. H. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1SJ (United Kingdom); Evans, D. A.; Kraft, R. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kharb, P.; Lenc, E. [Department of Physics, Rochester Institute of Technology, Rochester, NY 14623 (United States)

2012-10-20

 
 
 
 
41

Thermal X-Ray Emission from Shocked Ejecta in Type Ia Supernova Remnants II: Parameters Affecting the Spectrum  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The supernova remnants left behind by Type Ia supernovae provide an excellent opportunity for the study of these enigmatic objects. In a previous work, we showed that it is possible to use the X-ray spectra of young Type Ia supernova remnants to explore the physics of Type Ia supernovae and identify the relevant mechanism underlying these explosions. Our simulation technique is based on hydrodynamic and nonequilibrium ionization calculations of the interaction of a grid of T...

Badenes, C.; Borkowski, K. J.; Bravo, E.

2005-01-01

42

A Review of X-ray Observations of Supernova Remnants  

International Nuclear Information System (INIS)

I present a review of X-ray observations of supernova remnants with an emphasis on shell-type remnants. The topics discussed are the observation of fresh nucleosynthesis products, shock heating and cosmic ray acceleration

2004-06-01

43

Molecules and dust in Cas A: I - Synthesis in the supernova phase and processing by the reverse shock in the clumpy remnant  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aims: We study the chemistry of the Type IIb supernova ejecta that led to the Cas A supernova remnant to assess the chemical type and quantity of dust that forms and evolves in the remnant phase. We later model a dense oxygen-rich ejecta knot that is crossed by the reverse shock in Cas A to study the evolution of the clump gas phase and the possibility to reform dust clusters in the post-reverse shock gas. Methods: A chemical network including all processes efficient at hi...

Biscaro, Chiara; Cherchneff, Isabelle

2014-01-01

44

Cosmic-ray acceleration in supernova remnants  

CERN Document Server

Galactic cosmic rays are widely believed to be accelerated in expanding shock waves initiated by supernova explosions. The theory of diffusive shock acceleration of cosmic rays is now well established, but two fundamental questions remain partly unanswered: what is the acceleration efficiency, i.e. the fraction of the total supernova energy converted to cosmic-ray energy, and what is the maximum kinetic energy achieved by particles accelerated in supernova explosions? Recent observations of supernova remnants, in X-rays with the Chandra and XMM-Newton satellites and in very-high-energy gamma rays with several ground-based atmospheric Cerenkov telescopes, have provided new pieces of information concerning these two questions. After a review of these observations and their current interpretations, I show that complementary information on the diffusive shock acceleration process can be obtained by studying the radio emission from extragalactic supernovae. As an illustration, a nonlinear model of diffusive shock ...

Tatischeff, Vincent

2008-01-01

45

Infrared Studies of Molecular Shocks in the Supernova Remnant HB21: I. Thermal Admixture of Shocked H_2 Gas in the North  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 AKARI satellite and the Wide InfraRed Camera (WIRC) at the Palomar 5 m telescope. The IRC 7 um (S7), 11 um (S11), and 15 um (L15) band images and the WIRC H2 v = 1 -> 0 S(1) 2.12 um image show similar shock-cloud interaction features. We chose three representative regions, and analyzed their I...

Shinn, Jong-ho; Koo, Bon-chul; Burton, Michael G.; Lee, Ho-gyu; Moon, Dae-sik

2008-01-01

46

Cosmic ray ionisation of a molecular cloud shocked by the W28 supernova remnant  

CERN Document Server

Cosmic rays are an essential ingredient in the evolution of the interstellar medium, as they dominate the ionisation of the dense molecular gas, where stars and planets form. However, since they are efficiently scattered by the galactic magnetic fields, many questions remain open, such as where exactly they are accelerated, what is their original energy spectrum, and how they propagate into molecular clouds. In this work we present new observations and discuss in detail a method that allows us to measure the cosmic ray ionisation rate towards the molecular clouds close to the W28 supernova remnant. To perform these measurements, we use CO, HCO$^+$, and DCO$^+$ millimetre line observations and compare them with the predictions of radiative transfer and chemical models away from thermodynamical equilibrium. The CO observations allow us to constrain the density, temperature, and column density towards each observed position, while the DCO$^+$/HCO$^+$ abundance ratios provide us with constraints on the electron f...

Vaupré, Solenn; Ceccarelli, C; Dubus, G; Gabici, S; Montmerle, T

2014-01-01

47

Dust Destruction in Fast Shocks of Core-Collapse Supernova Remnants in the Large Magellanic Cloud  

CERN Multimedia

We report observations with the MIPS instrument aboard the {\\it Spitzer Space Telescope} (SST) of four supernova remnants (SNRs) believed to be the result of core-collapse SNe: N132D (0525-69.6), N49B (0525-66.0), N23 (0506-68.0), and 0453-68.5. All four of these SNRs were detected in whole at 24 $\\mu$m and in part at 70 $\\mu$m. Comparisons with {\\it Chandra} broadband X-ray images show an association of infrared (IR) emission with the blast wave. We attribute the observed IR emission to dust that has been collisionally heated by electrons and ions in the hot, X-ray emitting plasma, with grain size distributions appropriate for the LMC and the destruction of small grains via sputtering by ions. As with our earlier analysis of Type Ia SNRs, models can reproduce observed 70/24 $\\mu$m ratios only if effects from sputtering are included, destroying small grains. We calculate the mass of dust swept up by the blast wave in these remnants, and we derive a dust-to-gas mass ratio of several times less than the often a...

Williams, B J; Reynolds, S P; Blair, W P; Ghavamian, P; Hendrick, S P; Long, K S; Points, S; Raymond, J C; Sankrit, R; Smith, R C; Winkler, P F; Williams, Brian J.

2006-01-01

48

Antiprotons Produced in Supernova Remnants  

CERN Multimedia

We present the energy spectrum of antiproton cosmic ray (CR) component calculated on the basis of the nonlinear kinetic model of CR production in supernova remnants (SNR). The model includes reacceleration of already existing in interstellar medium antiprotons as well as creation of antiprotons in nuclear collisions of accelerated protons with gas nuclei and their subsequent acceleration by SNR shock. It is shown that antiprotons production in SNRs produces considerable effect in their resultant energy spectrum making it essentially flatter above 10 GeV so that the spectrum at TeV-energies increases by a factor of five. Calculated antiproton spectrum is well consistent with the PAMELA data, which correspond to energies below 100 GeV. As a consistency check we have also calculated within the same model the energy spectra of positrons and secondary nuclei and show that the measured boron-to-carbon and positron-to-electron ratios are consistent with the significant SNR contribution.

Berezhko, E G

2014-01-01

49

Probing the Reverse Shock in an Oxygen-Rich Supernovae Remnant  

Science.gov (United States)

The purpose of this investigation is to examine the O VI emission from the X-ray bright ring of the supernova remnant 1 E0102.2-729 in the small Magellanic cloud. Three pointings were positioned tangent to the ring, north (N), northeast (NE), and southeast (SE), to examine a range of X-ray emitting regions overlapping a range of optical [O III] nebulosity and to examine the velocity structure. One background pointing was also obtained, but it was contaminated by a star. The background levels in the pointings on the remnant were low enough that the background pointing was not required for the remaining analysis. The SE pointing was reobserved in August, 2004, in order to bring the total exposure up to the originally requested 15 ks. The archive notified us of the data's availability in mid September. Significant broad O VI 1032 and O VI 1038 emission was found, brightest in the NE and SE pointings. In the NE and SE pointings, the FWHM of the broad O VI component is approx.800-1000 km/s, while in the N pointing, the line is approx.1500 km/s wide. The O VI is redshifted in the N (approx.380 km/s) and NE (approx.60 km/s) but is blueshifted in the SE (approx. -160 km/s). These FUSE O VI velocity dispersions can be compared to the X-ray gas velocities inferred from Doppler distortions in the Chandra X-ray data as reported by Flanagan et al. 2004 (ApJ 605, 230). The bulk velocities in the X-ray bright ring of order +/- 1000 km/s, comparable to the velocity dispersion seen in the FUSE data. However, the X-ray data indicates a redshift of approx.1000 km/s in the SE, while the FUSE data show a blueshift of approx.160 km/s, underscoring the complex velocity structure in this remnant. The O VI fluxes estimated from the fits to the FUSE data were combined with X-ray (XMM- Newton) O VI1 and O VIII fluxes and compared with predictions from a plasma nonequilibrium ionization model in a "line-based" analysis. We found that the plasma departs significantly from collisional ionization equilibrium, particularly in the SE, and that the plasma excitation conditions vary among the pointings: the O plasma sees different conditions than the Ne and Mg plasmas.

Gaetz, Terrance (Principal Investigator); Sonneborn, George (Technical Monitor)

2005-01-01

50

X-ray spectra of supernova remnants  

International Nuclear Information System (INIS)

X-ray spectra were obtained from fields in three supernova remnants with the Solid-State Spectrometer of the HEAO-2 satellite. These spectra, which contain lines from K-shell transitions of several abundant elements with atomic numbers between 10 and 22, were compared with various models, including some of spectra that would be produced by adiabatic phase remnants when the time-dependence of the ionization is considered. There were significant differences between spectra obtained in different locations in the old supernova remnant Puppis A. The various spectra can be reproduced by a model of a shock having encountered regions of different density in material with standard elemental abundances. The inclusion of non-equilibrium ionization in the model makes the enhanced abundances which had been required in fits to other x-ray data unnecessary. The remnants of two suspected Type I supernova have spectra with lines much larger than could ever be produced by an adiabatic-phase remnant in cosmic abundance material. These line strengths, and indications from other wavelengths ranges and other instruments, suggest that these remnants may still be dominated by supernova ejecta

1984-01-01

51

Thermal X-ray emission from shocked ejecta in Type Ia Supernova Remnants. Prospects for explosion mechanism identification  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The explosion mechanism behind Type Ia supernovae is a matter of continuing debate. The diverse attempts to identify or at least constrain the physical processes involved in the explosion have been only partially successful so far. In this paper we propose to use the thermal X-ray emission from young supernova remnants originated in Type Ia events to extract relevant information concerning the explosions themselves. We have produced a grid of thermonuclear supernova models r...

Badenes, Carles; Bravo, Eduardo; Borkowski, Kazimierz J.; Dominguez, Inmaculada

2003-01-01

52

Localized SiO Emission Triggered by the Passage of the W51C Supernova Remnant Shock  

Science.gov (United States)

The region toward W51C is a convincing example of interaction between a supernova remnant (SNR) and a surrounding molecular cloud. Large electron abundances have been reported toward the position W51C-E located in this interaction region, and it was proposed that the enhanced ionization fraction was due to cosmic ray particles freshly accelerated by the SNR shock. We present Plateau de Bure Interferometer observations of the H13CO+(1-0) and DCO+(2-1) emission lines centered at position W51C-E. These observations confirm the previous scenario of cosmic-ray-induced ionization at this location. In addition, SiO(2-1) emission has been successfully mapped in the close vicinity of W51C-E, with a spatial resolution of 7''. The morphology and kinematics of the SiO emission are analyzed and strongly suggest that this emission is produced by the passage of the SNR primary shock. Put in conjunction with the enhanced ionization fraction in this region, we give a consistent picture in which the W51C-E position is located downstream of the shock, where a large reservoir of freshly accelerated particles is available.

Dumas, G.; Vaupré, S.; Ceccarelli, C.; Hily-Blant, P.; Dubus, G.; Montmerle, T.; Gabici, S.

2014-05-01

53

A Hubble Space Telescope Measurement of the Forward Shock Velocity of the Supernova Remnant 0509-67.5 in the Large Magellanic Cloud  

Science.gov (United States)

Using two Hubble Space Telescope narrow-band H? images of the supernova remnant 0509-67.5 taken ~1 year apart we determine the proper motion expansion of the remnant’s forward shock. The first epoch image was obtained with the Advanced Camera for Surveys, while the second epoch was taken with the Wide Field Planetary Camera 2. The supernova remnant 0509-67.5 is a rare specimen in that it is a Balmer-dominated remnant, and its light echoes have shown spectra showing it to be of Ia origin and likely analogous to a SN1991T-type explosion (Rest et al. 2008). After examining the expansion velocity versus position angle we find the remnant’s forward shock to have a velocity of 6,500±200 km/s. We also examine proper motions of the forward shock where deep optical spectroscopy had been previously obtained by Helder et al. 2010 in the north-east and south-west of the remnant, and directly compare the width (FWHM) (3,900±900 km/s) of the broad H? emission line to the forward shock velocity. Comparing these values, along with the measured broad-to-narrow ratio of 0.08±0.02 (Helder et al. 2010), allows us to constrain the degree of equilibration, ?, between shocked electrons and protons (Te,shocked/Tp,shocked) in the NE to be <0.03. We employ 1-D hydrodynamical simulations to constrain the density of the ambient medium and the age of the remnant. We use three different initial ejecta density profiles (power law profiles with indices of n=7 and n=4 plus an exponential profile) and we also vary the effective equation of state of the shocked interstellar material from a monatomic gas with ?=5/3 to an effective ?=1.1 to approximate the effect of efficient cosmic ray acceleration at the shock front. According to our analysis the remnant's age is between 230 and 390 years and it is expanding into an ambient medium with a density in the range 0.04-0.38 cm^{-3}.

Hovey, Luke; Hughes, J. P.; Eriksen, K.

2014-01-01

54

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

55

Infrared Studies of Molecular Shocks in the Supernova Remnant HB 21: II. Thermal Admixture of Shocked H$_2$ Gas in the South  

CERN Multimedia

We present near- and mid-infrared observations on the shock-cloud interaction region in the southern part of the supernova remnant HB 21, performed with the InfraRed Camera (IRC) aboard AKARI satellite and the Wide InfraRed Camera (WIRC) at the Palomar 5 m telescope. The IRC 4 um (N4), 7 um (S7), and 11 um (S11) band images and the WIRC H2 v=1->0 S(1) 2.12 um image show similar diffuse features, around a shocked CO cloud. We analyzed the emission through comparison with the H2 line emission 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 $T$, $dN\\sim T^{-b}dT$--with n(H2) $\\sim3.9\\times10^4$ cm^{-2}, $b\\sim4.2$, and N(H2;T>100K) $\\sim2.8\\times10^{21}$ cm^{-2}. We interpreted these parameters with several different pictures of the shock-cloud interactions--multiple planar C-shocks, bow shocks, and shocked clumps--and discuss their weaknesses and strengths. The observed H2 v=1...

Shinn, Jong-Ho; Burton, Michael G; Lee, Ho-Gyu; Moon, Dae-Sik

2009-01-01

56

Supernovae, young remnants, and nucleosynthesis  

International Nuclear Information System (INIS)

Supernovae and supernova remnants may be intimately linked to cosmic ray problems as the site of nucleosynthesis, the site of particle acceleration, or both. Although direct evidence for the origin of cosmic rays in supernovae remains elusive, observations of supernovae and their remnants by optical telescopes now provides good evidence that nuclear processing has taken place in these stars. The energetics and spectra of extragalactic supernovae immediately after the explosion indicate that Type I supernovae produce large amounts of iron peak elements. In a complementary way, spectroscopy of the 300 year old galactic remnant Cassiopeia A demonstrates that nuclear processing through oxygen burning took place in that object, which may have been a 15 to 25 solar mass star. The recent discovery of a handful of remnants with abundances like those in Cas A leads to the hope that a detailed correspondence between abundance patterns in these remnants and models for stellar interiors will provide new insight into the last stage of stellar evolution

1981-07-25

57

Particle simulation study of electron heating by counter-streaming ion beams ahead of supernova remnant shocks  

International Nuclear Information System (INIS)

The growth and saturation of Buneman-type instabilities is examined with a particle-in-cell (PIC) simulation for parameters that are representative for the foreshock region of fast supernova remnant shocks. A dense ion beam and the electrons correspond to the upstream plasma and a fast ion beam to the shock-reflected ions. The purpose of the 2D simulation is to identify the nonlinear saturation mechanisms, the electron heating and potential secondary instabilities that arise from anisotropic electron heating and result in the growth of magnetic fields. We confirm that the instabilities between both ion beams and the electrons saturate by the formation of phase space holes by the beam-aligned modes. The slower oblique modes accelerate some electrons, but they cannot heat up the electrons significantly before they are trapped by the faster beam-aligned modes. Two circular electron velocity distributions develop, which are centred around the velocity of each ion beam. They develop due to the scattering of the electrons by the electrostatic wave potentials. The growth of magnetic fields is observed, but their amplitude remains low. (paper)

2012-08-01

58

X-Ray Emission from Multi-Phase Shock in the Large Magellanic Cloud Supernova Remnant N49  

CERN Document Server

The supernova remnant (SNR) N49 in the Large Magellanic Cloud has been observed with the Advanced CCD Imaging Spectrometer (ACIS) on board the {\\it Chandra X-Ray Observatory}. The superb angular resolution of the {\\it Chandra}/ACIS images resolves a point source, the likely X-ray counterpart of soft gamma-ray repeater SGR 0526$-$66, and the diffuse filaments and knots across the SNR. These filamentary features represent the blast wave sweeping through the ambient interstellar medium and nearby dense molecular clouds. We detect metal-rich ejecta beyond the main blast wave shock boundary in the southwest of the SNR, which appear to be explosion fragments or ``bullets'' ejected from the progenitor star. The detection of strong H-like Si line emission in the eastern side of the SNR requires multi-phase shocks in order to describe the observed X-ray spectrum, whereas such a multi-phase plasma is not evident in the western side. This complex spectral structure of N49 suggests that the postshock regions toward the e...

Park, S; Garmire, G P; Nousek, J A; Hughes, J P; Williams, R M; Park, Sangwook; Burrows, David N.; Garmire, Gordon P.; Nousek, John A.; Hughes, John P.; Williams, Rosa Murphy

2003-01-01

59

Supernova remnant simulation experiments on VULCAN  

Science.gov (United States)

The VULCAN laser at the Central Laser Facility has been used for laboratory simulations of collision-less astrophysical shocks. By ensuring that the experiment exhibit similar values of key dimension-less parameters to those in supernova remnants the hydrodynamics and magnetic field of the experiment are scaled to those of SNR. This enables some of the most challenging aspects of shock behavior to be tested directly against experiment. The experiments provide dat against which to test current theory. Collision-less shock formation, and plasma interaction of two counter- propagating colliding foils permeated by a strong magnetic field are discussed.

Woolsey, N. C.; Abou Ali, Y.; Evans, R.; Grundy, R. A.; Peschte, S. J.; Carolan, P.; Conway, N.; Dendy, R. O.; Helander, P.; McClements, K. G.; Kirk, J. G.; Norreys, Peter A.; Notley, M. M.; Rose, S. J.

2001-04-01

60

Infrared Studies of Molecular Shocks in the Supernova Remnant HB21: I. Thermal Admixture of Shocked H_2 Gas in the North  

CERN Document Server

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 AKARI satellite and the Wide InfraRed Camera (WIRC) at the Palomar 5 m telescope. The IRC 7 um (S7), 11 um (S11), and 15 um (L15) band images and the WIRC H2 v = 1 -> 0 S(1) 2.12 um 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, dN ~ T^-b dT--with n(H2) ~ 10^3 cm^-3, b ~ 3, and N(H2 ;T > 100K) ~ 3x10^20 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-sc...

Shinn, Jong-Ho; Burton, Michael G; Lee, Ho-Gyu; Moon, Dae-Sik

2008-01-01

 
 
 
 
61

Nonthermal Radiation of Young Supernova Remnants  

CERN Multimedia

A new numerical code, designed for the detailed numerical treatment of nonlinear diffusive shock acceleration, is used for modeling of particle acceleration and radiation in young supernova remnants. The model is based on spherically symmetric hydrodynamic equations complemented with transport equations for relativistic particles. For the first time, the acceleration of electrons and protons by both forward and reverse shocks is studied through detailed numerical calculations. We model the energy spectra and spatial distributions of nonthermal emission of the young supernova remnant RX J1713.7-3946 and compare the calculations with the spectral and morphological properties of this object obtained in broad energy band from radio to very high energy gamma-rays. We discuss the advantages and shortcomings of the so-called hadronic and leptonic models which assume that the observed TeV gamma-ray emission is produced by accelerated protons and electrons, respectively. We discuss also a "composite" scenario when the...

Zirakashvili, V N

2009-01-01

62

Low Frequency Insights Into Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Low frequency observations at 330 and 74 MHz can provide new insights into supernova remnants (SNR). We can test theoretical predictions for spectral index variations. Nonlinear models of shock acceleration predict that the spectra from young SNR should be slightly concave rather than power laws -- flattening toward higher energies. However, few SNR are bright and compact enough to be studied at millimeter wavelengths, restricting studies to the small range from 6 to 20 cm (...

Dyer, Kristy K.; Reynolds, Stephen P.; Borkowski, Kazik J.

2000-01-01

63

Relationship between supernovae and their remnants  

International Nuclear Information System (INIS)

Arguments are presented to show that most of the known supernova remnants of the common 'shell-type' come from supernovae of type I. It is suggested that supernovae of type II also leave remnants, but of a short-lived 'plerion' type. Magnetic field-strengths, suitable for producing such remnants (e.g. the Crab), are discussed

1980-01-01

64

Non Parametric Determination of Acceleration Characteristics in Supernova Shocks Based on Spectra of Cosmic Rays and Remnant Radiation  

Science.gov (United States)

We have developed an inversion method for determination of the characteristics of the acceleration mechanism directly and non-parametrically from observations, in contrast to the usual forward fitting of parametric model variables to observations. This is done in the frame work of the so-called leaky box model of acceleration, valid for isotropic momentum distribution and for volume integrated characteristics in a finite acceleration site. We consider both acceleration by shocks and stochastic acceleration where turbulence plays the primary role to determine the acceleration, scattering and escape rates. Assuming a knowledge of the background plasma the model has essentially two unknown parameters, namely the momentum and pitch angle scattering diffusion coefficients, which can be evaluated given two independent spectral observations. These coefficients are obtained directly from the spectrum of radiation from the supernova remnants (SNRs), which gives the spectrum of accelerated particles, and the observed spectrum of cosmic rays (CRs), which are related to the spectrum of particles escaping the SNRs. The results obtained from application of this method will be presented.

Petrosian, Vahe; Chen, Qingrong

2014-06-01

65

X-ray spectroscopic measurements of non-equilibrium ionization in supernova remnants  

International Nuclear Information System (INIS)

Supernova remnants are modelled without assuming collisional ionization equilibrium. For supernova remnants within the density range 0.1 to 10/cm3 the equilibration time can be greater than the age of the remnant. Thus, even for relatively old remnants the most intense source may have been shocked relatively recently. 10 refs., 2 figs

1984-08-27

66

Molecular clouds near supernova remnants  

International Nuclear Information System (INIS)

The physical properties of molecular clouds near supernova remnants were investigated. Various properties of the structure and kinematics of these clouds are used to establish their physical association with well-known remmnants. An infrared survey of the most massive clouds revealed embedded objects, probably stars whose formation was induced by the supernova blast wave. In order to understand the relationship between these and other molecular clouds, a control group of clouds was also observed. Excitation models for dense regions of all the clouds are constructed to evaluate molecular abundances in these regions. Those clouds that have embedded stars have lower molecular abundances than the clouds that do not. A cloud near the W28 supernova remnant also has low abundances. Molecular abundances are used to measure an important parameter, the electron density, which is not directly observable. In some clouds extensive deuterium fractionation is observed which confirms electron density measurements in those clouds. Where large deuterium fractionation is observed, the ionization rate in the cloud interior can also be measured. The electron density and ionization rate in the cloud near W28 are higher than in most clouds. The molecular abundances and electron densities are functions of the chemical and dynamical state of evolution of the cloud. Those clouds with lowest abundances are probably the youngest clouds. As low-abundance clouds, some clouds near supernova remnants may have been recently swept from the local interstellar material. Supernova remnants provide sites for star formation in ambient clouds by compressing them, and they sweep new clouds from more diffuse local matter

1978-01-01

67

Future GLAST observations of Supernova remnants and Pulsar Wind Nebulae  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 lo...

Glast, Collaboration; Funk, S.

2007-01-01

68

X-ray Observations of Young Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This brief review of recent X-ray observations of young supernova remnants highlights results obtained by the Chandra and XMM Newton Observatories since their launch last year. Their impressive capabilities are illustrated by results for spectral imaging, and for spatially resolved spectroscopy that isolates emission from individual ejecta knots and from the forward shock. I also review X-ray dynamical studies of supernova remnants, which should undergo significant advances ...

Hwang, Una

2001-01-01

69

Magnetohydrodynamic turbulence in supernova remnants  

CERN Document Server

We present estimates of the angular power spectra of the synchrotron radiation intensity fluctuations at 6 and 20 cm for the shell type supernova remnant Cas A and the filled-centre Crab supernova remnant. We find that the intensity fluctuations of both sources have a power law power spectrum with index -3.24 +/- 0.03. This power law power spectrum is consistent with the magnetohydrodynamic turbulence in the synchrotron emitting plasma. For Cas A, there is a break in the power spectrum and the power law index changes from -3.2 to -2.2 at large angular scale. This transition occurs at an angular scale that corresponds to the shell thickness of Cas A. We interpret this as a transition from three dimensional turbulence to two dimensional turbulence on scales that are respectively smaller and larger than the shell thickness.

Roy, Nirupam; Dutta, Prasun; Chengalur, Jayaram N

2008-01-01

70

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

CERN Document Server

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 spectra of all components. The magnetic field amplification upstream is described as due to streaming instability of all nuclear species. The amplified magnetic field is then taken into account for its dynamical feedback on the shock structure as well as in terms of the induced modification of the velocity of the scattering centers that enters the particle transport equation. The spectra of accelerated particles are steep enough to be compared with observed cosmic ray spectra only if the magnetic field is sufficiently amplified and the scattering centers have high speed in the frame of the background plasma. We discuss the implications of this generalized approach on the structure of the knee in the all-particle cosmic ray spectrum, w...

Caprioli, D; Amato, E

2010-01-01

71

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

72

On the evolution of ejecta fragments in compact supernova remnants  

CERN Document Server

We examine the evolution of inhomogeneities (fragments) of supernova ejecta in compact supernova remnants by means of hydrodynamical modeling and simplified analytical calculations. Under the influence of intense post-shock cooling the fragments become strongly compressed as they traverse the hot shocked region between the reverse and outer shocks of the remnant. We find that the most likely outcome of the interaction of fragments with the reverse shock and the hot shocked region is their disruption resulting in generation of secondary fragments. Secondary fragments arriving at the thin and dense outer shell of the remnant give rise to brief X-ray flashes. Under suitable conditions the primary fragments may traverse the hot shocked region without being completely destroyed, to eventually reach the outer shell as dense, elongated structures. Collisions of such fragments with the shell are likely to give rise to powerful X-ray flares.

Cid-Fernandes, R; Rózyczka, M; Franco, J; Terlevich, R J; Tenorio-Tagle, G; Miller, W

1996-01-01

73

The Thermal Composite Supernova Remnant Kes 27 as Viewed by CHANDRA: Shock Reflection from a Cavity Wall  

CERN Multimedia

We present a spatially resolved spectroscopic study of the thermal composite supernova remnant Kes 27 with Chandra. The X-ray spectrum of Kes 27 is characterized by K lines from Mg, Si, S, Ar, and Ca. The X-ray emitting gas is found to be enriched in sulphur and calcium. The broadband and tri-color images show two incomplete shell-like features in the northeastern half and brightness fading with increasing radius in the southwest. There are over 30 unresolved sources within the remnant. None show characteristics typical of young neutron stars. The maximum diffuse X-ray intensity coincides with a radio bright region along the eastern border. In general, gas in the inner region is at higher temperature and emission is brighter than from the outer region. The gas in the remnant appears to approach ionization equilibrium. The overall morphology can be explained by the evolution of the remnant in an ambient medium with a density enhancement from west to east. We suggest that the remnant was born in a pre-existing ...

Chen, Yang; Sun, Ming; Li, Jiang-tao

2007-01-01

74

Hydrodynamic simulations of the interaction of supernova shock waves with a clumpy environment: the case of the RX J0852.0-4622 (Vela Jr) supernova remnant  

Science.gov (United States)

Observations in all electromagnetic bands show that many supernova remnants (SNRs) have a very aspherical shape. This can be the result of asymmetries in the supernova explosion or a clumpy circumstellar medium. We study the generation of inhomogeneities and the mixing of elements arising from these two sources in multidimensional hydrodynamic simulations of the propagation of a supernova blast wave into a cloudy environment. We model a specific SNR, Vela Jr (RX J0852.0-4622). By comparing our results with recent observations, we can constrain the properties of the explosion. We find that a very energetic explosion of several 1051 erg occurring roughly about 800 years ago is consistent with the shape and emission of the SNR, as well as a supernova with an energy closer to the canonical value of 1051 erg a few thousand years ago.

Obergaulinger, M.; Iyudin, A. F.; Müller, E.; Smoot, G. F.

2014-01-01

75

Neutron Stars in Supernova Remnants and Beyond  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

76

Molecules and dust in Cas A: I - Synthesis in the supernova phase and processing by the reverse shock in the clumpy remnant  

CERN Document Server

Aims: We study the chemistry of the Type IIb supernova ejecta that led to the Cas A supernova remnant to assess the chemical type and quantity of dust that forms and evolves in the remnant phase. We later model a dense oxygen-rich ejecta knot that is crossed by the reverse shock in Cas A to study the evolution of the clump gas phase and the possibility to reform dust clusters in the post-reverse shock gas. Methods: A chemical network including all processes efficient at high gas temperatures and densities is considered. The formation of key bimolecular species (CO, SiO) and dust clusters is described. Stiff, coupled, ordinary, differential equations are solved for the conditions pertaining to both the SN ejecta and the post-reverse shock gas. Results: We find that the ejecta of Type IIb SNe are unable to form large amounts of molecules and dust clusters as opposed to their Type II-P counterparts because of their diffuse ejecta. The gas density needs to be increased by several orders of magnitude to allow the ...

Biscaro, Chiara

2014-01-01

77

Supernova Remnant in 3-D  

Science.gov (United States)

[figure removed for brevity, see original site] Click on the image for the movie For the first time, a multiwavelength three-dimensional reconstruction of a supernova remnant has been created. This stunning visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several telescopes: X-ray data from NASA's Chandra X-ray Observatory, infrared data from NASA's Spitzer Space Telescope and optical data from the National Optical Astronomy Observatory 4-meter telescope at Kitt Peak, Ariz., and the Michigan-Dartmouth-MIT 2.4-meter telescope, also at Kitt Peak. In this visualization, the green region is mostly iron observed in X-rays. The yellow region is a combination of argon and silicon seen in X-rays, optical, and infrared including jets of silicon plus outer debris seen in the optical. The red region is cold debris seen in the infrared. Finally, the blue reveals the outer blast wave, most prominently detected in X-rays. Most of the material shown in this visualization is debris from the explosion that has been heated by a shock moving inwards. The red material interior to the yellow/orange ring has not yet encountered the inward moving shock and so has not yet been heated. These unshocked debris were known to exist because they absorb background radio light, but they were only recently discovered in infrared emission with Spitzer. The blue region is composed of gas surrounding the explosion that was heated when it was struck by the outgoing blast wave, as clearly seen in Chandra images. To create this visualization, scientists took advantage of both a previously known phenomenon the Doppler effect and a new technology that bridges astronomy and medicine. When elements created inside a supernova, such as iron, silicon and argon, are heated they emit light at certain wavelengths. Material moving towards the observer will have shorter wavelengths and material moving away will have longer wavelengths. Since the amount of the wavelength shift is related to the speed of motion, one can determine how fast the debris are moving in either direction. Because Cas A is the result of an explosion, the stellar debris is expanding radially outwards from the explosion center. Using simple geometry, the scientists were able to construct a 3-D model using all of this information. A program called 3-D Slicer modified for astronomical use by the Astronomical Medicine Project at Harvard University in Cambridge, Mass. was used to display and manipulate the 3-D model. Commercial software was then used to create the 3-D fly-through. The blue filaments defining the blast wave were not mapped using the Doppler effect because they emit a different kind of light synchrotron radiation that does not emit light at discrete wavelengths, but rather in a broad continuum. The blue filaments are only a representation of the actual filaments observed at the blast wave. This visualization shows that there are two main components to this supernova remnant: a spherical component in the outer parts of the remnant and a flattened (disk-like) component in the inner region. The spherical component consists of the outer layer of the star that exploded, probably made of helium and carbon. These layers drove a spherical blast wave into the diffuse gas surrounding the star. The flattened component that astronomers were unable to map into 3-D prior to these Spitzer observations consists of the inner layers of the star. It is made from various heavier elements, not all shown in the visualization, such as oxygen, neon, silicon, sulphur, argon and iron. High-velocity plumes, or jets, of this material are shooting out from the explosion in the plane of the disk-like component mentioned above. Plumes of silicon appear in the northeast and southwest, while those of iron are seen in the southeast and north. These jets were already known and Doppler velocity measurements have been made for these structures, but their orientation and position with resp

2009-01-01

78

The Thermal Composite Supernova Remnant Kes 27 as Viewed by CHANDRA: Shock Reflection from a Cavity Wall  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a spatially resolved spectroscopic study of the thermal composite supernova remnant Kes 27 with Chandra. The X-ray spectrum of Kes 27 is characterized by K lines from Mg, Si, S, Ar, and Ca. The X-ray emitting gas is found to be enriched in sulphur and calcium. The broadband and tri-color images show two incomplete shell-like features in the northeastern half and brightness fading with increasing radius in the southwest. There are over 30 unresolved sources within ...

Chen, Yang; Seward, Frederick D.; Sun, Ming; Li, Jiang-tao

2007-01-01

79

The blast wave of Tycho's supernova remnant  

CERN Document Server

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 time evidence for significant spatial variations of the X-ray synchrotron emission in the form of spectral steepening from a photon index of 2.6 right at the blast wave to a value of 3.0 several arcseconds behind. We interpret this result along with the profiles of radio and X-ray intensity using a self-similar hydrodynamical model including cosmic ray backreaction that accounts for the observed ratio of radii between the blast wave and contact discontinuity. Two different assumptions were made about the post-shock magnetic field evolution: one where the magnetic field (amplified at the shock) is simply carried by the plasma flow and remains relatively high in the post-shock region [synchrotron losses limited rim cas...

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

2007-01-01

80

Prospects for SNIa Explosion Mechanism Identification Through Supernova Remnants  

CERN Document Server

We present the first results from an ongoing work aimed to use supernovae remnants to discriminate among different type Ia supernovae explosion models. We have computed the hydrodynamic interaction of supernova ejecta with the interstellar medium, obtaining the evolution of the density, temperature and ionization structure of the remnant. We have used ejecta profiles obtained from 1D hydrodynamic calculations of the different explosion mechanisms that are currently under debate. We have analyzed the best indicators that allow to discriminate among the different explosion mechanisms, taking into account the diversity of scenarios proposed for the presupernova evolution of the binary system, and the uncertain amount of electron heating in collisionless shocks.

Badenes, C; Badenes, Carles; Bravo, Eduardo

2002-01-01

 
 
 
 
81

Low Frequency Insights Into Supernova Remnants  

CERN Multimedia

Low frequency observations at 330 and 74 MHz can provide new insights into supernova remnants (SNR). We can test theoretical predictions for spectral index variations. Nonlinear models of shock acceleration predict that the spectra from young SNR should be slightly concave rather than power laws -- flattening toward higher energies. However, few SNR are bright and compact enough to be studied at millimeter wavelengths, restricting studies to the small range from 6 to 20 cm (a factor of 1.7 in electron energies). Observations at 330 MHz increase the electron energy baseline to a factor of 4, while providing sensitivity to larger spatial scales that are resolved out by centimeter-wavelength interferometers. Such observations can also separate thermal from nonthermal emission and detect excess free-free absorption associated with cool gas in remnants. Wide field images also provide an efficient census of both thermal and nonthermal sources over a large region.

Dyer, K K; Borkowski, K J; Dyer, Kristy K.; Reynolds, Stephen P; Borkowski, Kazik J.

2000-01-01

82

Multi-Wavelength Observations of Supernova Remnants  

Science.gov (United States)

Supernova remnants (SNRs) provide a laboratory for studying various astrophysical processes, including particle acceleration, thermal and non thermal emission processes across the spectrum, distribution of heavy elements, the physics of strong shock waves, and the progenitor systems and environments of supernovae. Long studied in radio and X-rays, the past decade has seen a dramatic increase in the detection and subsequent study of SNRs in the infrared and gamma-ray regimes. Understanding the evolution of SNRs and their interaction with the interstellar medium requires a multi-wavelength approach. I will review the various physical processes observed in SNRs and how these processes are intertwined. In particular, I will focus on X-ray and infrared observations, which probe two very different but intrinsically connected phases of the ISM: gas and dust. I will discuss results from multi-wavelength studies of several SNRs at various stages of evolution, including Kepler, RCW 86, and the Cygnus Loop.

Williams, B.

2012-01-01

83

Vivid View of Tycho's Supernova Remnant  

Science.gov (United States)

This composite image of the Tycho supernova remnant combines infrared and X-ray observations obtained with NASA's Spitzer and Chandra space observatories, respectively, and the Calar Alto observatory, Spain. It shows the scene more than four centuries after the brilliant star explosion witnessed by Tycho Brahe and other astronomers of that era. The explosion has left a blazing hot cloud of expanding debris (green and yellow). The location of the blast's outer shock wave can be seen as a blue sphere of ultra-energetic electrons. Newly synthesized dust in the ejected material and heated pre-existing dust from the area around the supernova radiate at infrared wavelengths of 24 microns (red). Foreground and background stars in the image are white.

2008-01-01

84

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

85

Supernova remnants: the X-ray perspective  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Supernova remnants are beautiful astronomical objects that are also of high scientific interest, because they provide insights into supernova explosion mechanisms, and because they are the likely sources of Galactic cosmic rays. X-ray observations are an important means to study these objects.And in particular the advances made in X-ray imaging spectroscopy over the last two decades has greatly increased our knowledge about supernova remnants. It has made it possible to map ...

Vink, Jacco

2011-01-01

86

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 inside of the shock front, and no losses or gain of energy at the front, seems therefore unjustified.

Barenblatt, Grigory Isaakovich

2008-01-01

87

Interaction of High-Velocity Pulsars with Supernova Remnant Shells  

CERN Multimedia

Hydrodynamical simulations are presented of a pulsar wind emitted by a supersonically moving pulsar. The pulsar moves through the interstellar medium or, in the more interesting case, through the supernova remnant created at its birth event. In both cases there exists a three-fold structure consisting of the wind termination shock, contact discontinuity and a bow shock bounding the pulsar wind nebula. Using hydrodynamical simulations we study the behaviour of the pulsar wind nebula inside a supernova remnant, and in particular the interaction with the outer shell of swept up interstellar matter and the blast wave surrounding the remnant. This interaction occurs when the pulsar breaks out of the supernova remnant. We assume the remnant is in the Sedov stage of its evolution. Just before break-through, the Mach number associated with the pulsar motion equals ${\\cal M}_{\\rm psr} = 7/\\sqrt{5}$, {\\em independent} of the supernova explosion energy and pulsar velocity. The bow shock structure is shown to survive thi...

Der Swaluw, E; Gallant, Y A; Downes, T P; Keppens, R

2003-01-01

88

Ortho-to-Para Ratio Studies of Shocked H2 Gas in the Two Supernova Remnants IC 443 and HB 21  

CERN Document Server

We present near-infrared (2.5-5.0 {\\mu}m) spectral studies of shocked H2 gas in the two supernova remnants IC 443 and HB 21, which are well known for their interactions with nearby molecular clouds. The observations were performed with Infrared Camera (IRC) aboard the AKARI satellite. At the energy range 7000 K <= E(v,J) <= 20000 K, the shocked H2 gas in IC 443 shows an ortho-to-para ratio (OPR) of 2.4+0.3-0.2, which is significantly lower than the equilibrium value 3, suggesting the existence of non-equilibrium OPR. The shocked gas in HB 21 also indicates a potential non-equilibrium OPR in the range of 1.8-2.0. The level populations are well described by the power-law thermal admixture model with a single OPR, where the temperature integration range is 1000-4000 K. We conclude that the obtained non-equilibrium OPR probably originates from the reformed H2 gas of dissociative J-shocks, considering several factors such as the shock combination requirement, the line ratios, and the possibility that H2 gas ...

Shinn, Jong-Ho; Moon, Dae-Sik

2012-01-01

89

CCD observations of supernova remnants  

International Nuclear Information System (INIS)

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

90

Filamentary structure of old optical supernova remnants  

International Nuclear Information System (INIS)

Interferometric and spectroscopic observations of optical supernova remnants that bear on the problem of how the fine filamentary structure is formed are summarized. A morphological classification of the nebulae observed is presented, and its relation to the physical parameters of the remnants and the ambient interstellar medium is examined. In addition, the spatial configuration and the optical emission of the filaments are analyzed. It is found that the filaments represent dense ropes or filaments embedded in amorphous gas of lower density. Their thickness, 0.001 to 0.01 pc, is comparable with the thickness of the radiative region behind the shock front, and the density of the luminous gas, (0.5-2) x 10 to the 3rd per cu cm, is about two orders of magnitude higher than the typical undisturbed density in the cloud component of the interstellar medium. The thin filamentary structure develops primarily in remnants which are young in evolutionary terms, are in their adiabatic expansion phase, and have a high luminosity (not less than 10 to the 35th erg/sec) in the soft X-ray range

1980-11-01

91

Limits on Enhanced Radio Wave Scattering by Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report multifrequency observations with the NRAO Very Long Baseline Array (VLBA) of the compact radio sources J0128+6306 and J0547+2721, which are viewed through the supernova remnants G127.1+0.5 and S147, respectively. Observations were made at frequencies of 1.427, 1.667, 2.271, and 4.987 GHz. The lines of sight to these sources pass through the shock wave and upstream and downstream turbulent layers of their respective supernova remnants, and thus might detect cosmic-r...

Spitler, Laura G.; Spangler, Steven R.

2005-01-01

92

On the evolution of supernova remnants: Pt. 1  

International Nuclear Information System (INIS)

This paper presents numerical calculations, under the assumption of spherical symmetry, of the evolution of supernova remnants resulting from explosions inside wind-driven bubbles excavated by the progenitor stars. The complex structure of the wind bubble is determined by means of a numerical, time-dependent calculation. The supernovae ejecta generate a variety of reflected and transmitted shocks, a complex velocity field, and a variability in the time evolution of the X-ray and H? emission. The calculations are continued far into the phase of strong radiative cooling in the outer shell of the remnants. (author)

1990-06-01

93

Acoustic waves in supernova remnants  

International Nuclear Information System (INIS)

When the Mach number of a supernova shock wave, propagating through the hot interstellar gas, is less than the critical value 2.76, the interaction of the shock with an interstellar cloud produces a reflected pressure pulse that propagates away from the cloud as an acoustic wave. A preliminary analysis indicates that about 4% of the energy of an exploding supernova shell is converted into such waves. When the postshock gas temperature exceeds 2 x 10_6 K, waves as short as 6 pc are damped in less than a wavelength, returning the energy to the hot gas. Longer waves, especially at later stages, are less strongly damped, and are superposed in the hot gas to create a fluctuating magnetoacoustic field, with typical periods of about 10_5 years. In the warm neutral clouds at temperatures of about 8000 K these waves are rapidly damped by plasma slip (ambipolar diffusion), providing a heat source that may account for the temperatures of thse clouds

1982-11-01

94

Multiwavelength investigation of the supernova remnant IC 443  

International Nuclear Information System (INIS)

Multiwavelength observations of the supernova remnant IC 443 at radio, infrared, optical, ultraviolet, and X-ray wavelengths are presented. This morphological study of IC 443 presents a detailed picture of an adolescent supernova remnant in a multiphase interstellar medium. Radio observations show that better than 80 percent of the continuum emission at 18 cm is in a large-scale (greater than 18 arcmin) component. Decomposition of the infrared data shows that radiatively heated dust, shocked blackbody dust emission, and infrared line emission are all important components of the observed IRAS fluxes. The morphology of the IC 443 region is consistent with a supernova blast in an interstellar medium with a nonuniform distribution of clouds. The bright northeast rim and the great extent of the remnant to the southwest are most easily explained by a cloud filling factor which is greatest in the northeast and falls off toward the southwest. 64 references

1986-01-01

95

New Galactic supernova remnants discovered with IPHAS  

CERN Document Server

As part of a systematic search programme of a 10-degree wide strip of the Northern Galactic plane we present preliminary evidence for the discovery of four (and possibly five) new supernova remnants (SNRs). The pilot search area covered the 19-20 hour right ascension zone sampling from +20 to +55 degrees in declination using binned mosaic images from the INT Photometric H-alpha Survey (IPHAS). The optical identification of the candidate SNRs was based mainly on their filamentary and arc-like emission morphologies, their apparently coherent, even if fractured structure and clear disconnection from any diffuse neighbouring HII region type nebulosity. Follow-up optical spectroscopy was undertaken, sampling carefully across prominent features of these faint sources. The resulting spectra revealed typical emission line ratios for shock excited nebulae which are characteristic of SNRs, which, along with the latest diagnostic diagrams, strongly support the likely SNR nature of these sources: G038.7-1.3 (IPHASX J1906...

Sabin, L; Contreras, M E; Olguín, L; Frew, D J; Stupar, M; Vázquez, R; Wright, N J; Corradi, R L M; Morris, R A H

2013-01-01

96

Infrared [Fe II] and Dust Emissions from Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 molec...

Koo, Bon-chul

2013-01-01

97

Hydrodynamic instabilities in supernova remnants - Self-similar driven waves  

Science.gov (United States)

An initial study aimed at elucidating the multidimensional aspects of the hydrodynamic instabilities in supernova remnants is presented. Self-similar solutions are found to exist for the interaction of a steep power-law density profile expanding into a relatively flat stationary power-law density profile. Consideration of the pressure and entropy profiles in the shocked 1D flows shows that the flows are subject to convective instability, by a local criterion. The growth rate for the instability becomes very large near the contact discontinuity between the two shocked regions. A linear analysis of the complete self-similar solutions shows that the solutions are unstable above a critical wavenumber and that the growth rate is greatest at the position of the contact discontinuity. The X-ray image of the remnant of SN 1572 (Tycho) shows emission from clumps of supernova ejecta, which is good evidence for instabilities in this remnant.

Chevalier, Roger A.; Blondin, John M.; Emmering, Robert T.

1992-06-01

98

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

99

Young Supernova Remnants in the Magellanic Clouds  

CERN Document Server

There are a half-dozen or so young supernova remnants in the Magellanic Clouds that display one or more of the following characteristics: high velocity (>1000 km/s) emission, enhanced metallicity, or a rapidly rotating pulsar. I summarize the current state of knowledge of these remnants and present some recent results mostly from the new X-ray astronomy satellites.

Hughes, J P

2001-01-01

100

Young Supernova Remnants: Issues and Prospects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

After reviewing recent work on the dynamics of young supernova remnants (YSNRs) and discussing how YSNRs can be used as physics laboratories, I discuss several challenges: Where are the very young SNRs in the Galaxy? Can very young SNRs produce gamma ray bursts? The Connections Challenge: Can one infer the nature of the supernova and its progenitor star from observations of the YSNR?

Mckee, Christopher F.

2001-01-01

 
 
 
 
101

Circumstellar Nebulae in Young Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Supernovae descendent from massive stars explode in media that have been modified by their progenitors' mass loss and UV radiation. The supernova ejecta will first interact with the circumstellar material shed by the progenitors at late evolutionary stages, and then interact with the interstellar material. Circumstellar nebulae in supernova remnants can be diagnosed by their small expansion velocities and high [N II]/H$\\alpha$ ratios. The presence of circumstellar nebulae ap...

Chu, Y. -h

2000-01-01

102

Molecular clouds near supernova remnants  

International Nuclear Information System (INIS)

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

103

Evolution of supernova remnants with a central pulsar  

International Nuclear Information System (INIS)

The data of observations of plerions and combined supernova remnants with a central pulsar are discussed. It is shown that the age t, dimension D or the pulsar energy loss rate E, taken separately, are bad indicators of the plerion evolutionary stage. As an evolutionary age indicator, the parameters combination Et/V (V being the plerion volume) is suggested; this allowed to represent four remnants with pulsars as a single evolutionary sequence. The hypothetical pulsar in 3C 58 differs from the pulsars of similar age in Crab Nebula and in 0540-693 object by the low energy loss rate. The observed dependence agrees with the theory of Reynolds and Chevalier if the four remnants with pulsars are at the stage after the passage of the reverse shock wave initiated by the deceleration of the ejection. The location of shells of the combined supernova remnants on the composite ?(D) dependence of brightness ? on dimensons D for supernova remnants in the Galaxy, LMC, M 33 and M 31, lends support to earlier auther suggestion on the plerinos turning into the shell remnants. The evolutionary status is discussed of the Crab Nebula and the synchrotron X-ray nebulae surrounding isolated radio pulsars. The existence of old large plerions without any hints of shell is explained by their location in the rarefied medium of density n_0 ? 10"-"2 cm"-"3

1986-01-01

104

H-alpha images of the Cygnus Loop - A new look at shock-wave dynamics in an old supernova remnant  

Science.gov (United States)

Attention is given to deep H-alpha images of portions of the east, west, and southwest limbs of the Cygnus Loop which illustrate several aspects of shock dynamics in a multiphase interstellar medium. An H-alpha image of the isolated eastern shocked cloud reveals cloud deformation and gas stripping along the cloud's edges, shock front diffraction and reflection around the rear of the cloud, and interior remnant emission due to upstream shock reflection. A faint Balmer-dominated filament is identified 30 arcmin further west of the remnant's bright line of western radiative filaments. This detection indicates a far more westerly intercloud shock front position than previously realized, and resolves the nature of the weak X-ray, optical, and nonthermal radio emission observed west of NGC 6960. Strongly curved Balmer-dominated filaments along the remnant's west and southwest edge may indicate shock diffraction caused by shock wave passage in between clouds.

Fesen, Robert A.; Kwitter, Karen B.; Downes, Ronald A.

1992-01-01

105

Velocity and spectrum of the supernova remnant 30 Dor B  

International Nuclear Information System (INIS)

An analysis is presented of the spectrum of the supernova remnant 30 Doradus B (N175 B), within the 30 Dor B HII region in the Large Magellanic Cloud. The data yield a velocity dispersion estimate (>approximately 630 km s"-_1) and the size of the remnant (rsub(shock)<= 30 arcsec identical to 7 pc). The remnant properties suggest that the supernova outburst energy was E"0, such that E"0/nsub(H) < approximately 3 x 10_5_0 erg cm_3. Since nsub(H) approximately 40 cm"-_3 in the surrounding medium, the outburst energy E"0 < approximately 2 x 10_5_2 erg. A Type II classification accords with its association with Population I. In its radio and X-ray properties 30 Dor B resembles the Crab Nebula, but continuum emission from 30 Dor B correlates with H#betta# emission and is probably from two-photon hydrogen recombination. (author)

1983-01-01

106

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Drury, L. O. C.; Swaluw, E.; Carroll, O.

2003-01-01

107

Observations of Supernova Remnants with VERITAS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The study of shell-type supernova remnants is a key science focus for the VERITAS TeV telescope array. Supernova remnants (SNRs) are widely considered to be the strongest candidate for the source of cosmic rays below the knee around 10^15 eV. This presentation will highlight new VERITAS results including new measurements of the spectra of Cas A and IC 443 and observations of the "Forbidden Velocity Wing" FVW 190.2+1.1. These results and their implications for the nature of t...

Humensky, Brian; Collaboration, For The Veritas

2009-01-01

108

Complex structure of the supernova remnant HB 3  

International Nuclear Information System (INIS)

HB 3 is an old, large (84 pc diameter) supernova remnant associated with the W3 H II region/molecular cloud complex. Observations of the imaging proportional counter (IPC) onboard the Einstein X-ray astronomy satellite have been reprocessed to yield a contour map of X-ray brightness and spectra of various regions of this remnant. The measured IPC flux is 2.4 x 10 to the -11th ergs per sq cm per s, giving a 0.2-4 keV luminosity of 1.6 x 10 to the 35th ergs/s for a column densityof 6 x 10 to the 21st per sq cm. The measured X-ray temperatures reveal a decrease from center to limb of the remnant of 1-0.3 keV. HB 3 is in the late adiabatic blast-wave phase of evolution, 30,000 to 50,000 yr old and with an initial blast energy of 3 x 10 to the 50th ergs. The X-ray map is compared with available radio and optical images. In X-rays, HB 3 has two components - a diffuse emission inside the 84 pc radio remnant and a ring of emission at the center of 30 pc in diameter. The diffuse emission is similar to that from other supernova remnants which are moderately obscured (column density, nH approximately 10 to the 22nd per sq cm). Three possibilities for the origin of the ring are explored: (1) a second supernova remnant, (2) a shocked shell in the interstellar medium surrounding HB 3, and (3) reverse-shock heated ejecta. There is no hot neutron star within the remnant. 30 references

1985-01-01

109

Thermal X-ray Spectra of Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 nucleosyn...

Slane, Patrick

2013-01-01

110

X-Ray Measured Dynamics of Tycho's Supernova Remnant  

Science.gov (United States)

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 [approx]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 [less, similar]0.2 cm-3.

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

2010-01-01

111

Fine-fibered structure of old optical supernova remnants  

International Nuclear Information System (INIS)

The results of interferrometric and spectral observations of optical supernova remnants concerning the nature of fine-fibered formations are presented. A morphological classification of the nebulae investigated is performed, its relation to physical parameters of the remnants and interstellar environment is analyzed. Spatial geometry and optical filament emission are discussed. The results of observations of thin filaments in old remnants state that the filaments represent dense bunches or cylinders submerged into the less density amorphous gas. The filament thickness 10-2-10-3 ps is comparable to the thickness of the glow region behind the shock wave front. The luminescent gas density (5x102-2x103 cm-3) is approximately two orders higher of the characteristic nonturbulent density in nebulous component of the interstellar environment. It is pointed out that thin filament observation data in the first approximation are described by the shock waves crossing model

1980-11-01

112

The Structure of the Oxygen-rich Supernova Remnant G292.0+1.8 from Chandra X-ray Images Shocked Ejecta and Circumstellar Medium  

CERN Document Server

We present results from the observation of the young Galactic supernova remnant (SNR) G292.0+1.8 with the Advanced CCD Imaging Spectrometer (ACIS) on board the {\\it Chandra X-ray Observatory}. In the 0.3 $-$ 8 keV band, the high resolution ACIS images reveal a complex morphology consisting of knots and filaments, as well as the blast wave around the periphery of the SNR. We present equivalent width (EW) maps for the elemental species O, Ne, Mg, and Si, which allow us to identify regions of enhanced metallicity in the SNR. G292.0+1.8 is bright in O, Ne, and Si; weaker in S and Ar; with little Fe. The EW and broad-band images indicate that the metal-rich ejecta are distributed primarily around the periphery of the SNR. The central belt-like structure has normal solar-type composition, strongly suggesting that it is primarily emission from shocked circumstellar medium rather than metal-rich ejecta. We propose that the belt traces its origin to enhanced mass loss in the star's equatorial plane during the slow, re...

Park, S; Hughes, J P; Slane, P O; Burrows, D N; Garmire, G P; Nousek, J A; Park, Sangwook; Roming, Peter W. A.; Hughes, John P.; Slane, Patrick O.; Burrows, David N.; Garmire, Gordon P.; Nousek, John A.

2001-01-01

113

Nonthermal Radiation from Type Ia Supernova Remnants  

CERN Multimedia

We present calculations of expected continuum emissions from Sedov-Taylor phase Type Ia supernova remnants (SNRs), using the energy spectra of cosmic ray (CR) electrons and protons from nonlinear diffusive shock acceleration (DSA) simulations. A new, general-purpose radiative process code, Cosmicp, was employed to calculate the radiation expected from CR electrons and protons and their secondary products. These radio, X-ray and gamma-ray emissions are generally consistent with current observations of Type Ia SNRs. The emissions from electrons in these models dominate the radio through X-ray bands. For warm ISM cases (n_{ISM}=0.3 cm^{-3}), thermal bremsstrahlung becomes the dominant component in the UV to X-rays at late times. Decays of \\pi^0 s from p-p collisions mostly dominate the gamma-ray range, although for a hot, low density ISM case (n_{ISM}=0.003 cm^{-3}), the pion decay contribution is reduced sufficiently to reveal the inverse Compton contribution to TeV gamma-rays. In addition, we present simple sc...

Edmon, Paul P; Jones, T W; Ma, Renyi

2011-01-01

114

Gamma-Ray Emission From Crushed Clouds in Supernova Remnants  

Energy Technology Data Exchange (ETDEWEB)

It is shown that the radio and gamma-ray emission observed from newly-found 'GeV-bright' supernova remnants (SNRs) can be explained by a model, in which a shocked cloud and shock-accelerated cosmic rays (CRs) frozen in it are simultaneously compressed by the supernova blastwave as a result of formation of a radiative cloud shock. Simple reacceleration of pre-existing CRs is generally sufficient to power the observed gamma-ray emission through the decays of {pi}{sup 0}-mesons produced in hadronic interactions between high-energy protons (nuclei) and gas in the compressed-cloud layer. This model provides a natural account of the observed synchrotron radiation in SNRs W51C, W44 and IC 443 with flat radio spectral index, which can be ascribed to a combination of secondary and reaccelerated electrons and positrons.

Uchiyama, Yasunobu; Blandford, Roger D.; Funk, Stefan; /SLAC; Tajima, Hiroyasu; /Nagoya U., Solar-Terrestrial Environ. Lab.; Tanaka, Takaaki; /KIPAC, Menlo Park

2010-10-27

115

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

116

Chandra LETG Observations of Supernova Remnant 1987A  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We discuss the results from deep Chandra LETG observations of the supernova remnant 1987A (SNR 1987A). We find that a distribution of shocks, spanning the same range of velocities (from 300 to 1700 km/s) as deduced in the first part of our analysis (Zhekov et al. 2005, ApJL, 628, L127), can account for the entire X-ray spectrum of this object. The post-shock temperature distribution is bimodal, peaking at kT 0.5 and 3 keV. Abundances inferred from the X-ray spectrum have val...

Zhekov, Svetozar A.; Mccray, Richard; Borkowski, Kazimierz J.; Burrows, David N.; Park, Sangwook

2006-01-01

117

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

118

Fermi LAT Observations of Supernova Remnants Interacting with Molecular Clouds  

CERN Document Server

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

119

Exploring the Physics of Type Ia Supernovae Through the X-ray Spectra of their Remnants  

CERN Multimedia

We present the results of an ongoing project to use the X-ray observations of Type Ia Supernova Remnants to constrain the physical processes involved in Type Ia Supernova explosions. We use the Tycho Supernova Remnant (SN 1572) as a benchmark case, comparing its observed spectrum with models for the X-ray emission from the shocked ejecta generated from different kinds of Type Ia explosions. Both the integrated spectrum of Tycho and the spatial distribution of the Fe and Si emission in the remnant are well reproduced by delayed detonation models with stratified ejecta. All the other Type Ia explosion models fail, including well-mixed deflagrations calculated in three dimensions.

Badenes, C; Bravo, E; Hughes, J P; Hwang, U

2005-01-01

120

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

International Nuclear Information System (INIS)

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

 
 
 
 
121

A 3D numerical model for Kepler's supernova remnant  

Science.gov (United States)

We present new 3D numerical simulations for Kepler's supernova remnant. In this work we revisit the possibility that the asymmetric shape of the remnant in X-rays is the product of a Type Ia supernova explosion which occurs inside the wind bubble previously created by an AGB companion star. Due to the large peculiar velocity of the system, the interaction of the strong AGB wind with the interstellar medium results in a bow shock structure. In this new model we propose that the AGB wind is anisotropic, with properties such as mass-loss rate and density having a latitude dependence, and that the orientation of the polar axis of the AGB star is not aligned with the direction of motion. The ejecta from the Type Ia supernova explosion is modelled using a power-law density profile, and we let the remnant evolve for 400 yr. We computed synthetic X-ray maps from the numerical results. We find that the estimated size and peculiar X-ray morphology of Kepler's supernova remnant are well reproduced by considering an AGB mass-loss rate of 10-5 M? yr-1, a wind terminal velocity of 10 km s-1, an ambient medium density of 10-3 cm-3 and an explosion energy of 7 × 1050 erg. The obtained total X-ray luminosity of the remnant in this model reaches 6 × 1050 erg, which is within a factor of 2 of the observed value, and the time evolution of the luminosity shows a rate of decrease in recent decades of ˜2.4 per cent yr-1 that is consistent with the observations.

Toledo-Roy, J. C.; Esquivel, A.; Velázquez, P. F.; Reynoso, E. M.

2014-07-01

122

Parametric studies of cosmic ray acceleration in supernova remnants  

CERN Document Server

We present a library of numerical models of cosmic-ray accelerating supernova remnants (SNRs) evolving through a homogeneous ambient medium. We analyse distributions of the different energy components and diffusive shock acceleration time-scales for the models in various conditions. The library comprises a variety of SNR evolutionary scenarios and is used to map remnants with sufficiently known properties. This mapping constrains the respective ambient medium properties and the acceleration efficiency. Employing the library, we derive the ambient medium density, ambient magnetic field strength and the cosmic-ray acceleration efficiency for models of Tycho and SN 1006 remnants and refine the ages of SNR 0509-67.5 and SNR 0519-69.0.

Kosenko, D; Decourchelle, A

2014-01-01

123

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

124

Nonuniform abundances in young supernova remnants  

International Nuclear Information System (INIS)

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 "5"6Ni. 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

125

On the Origin of Asymmetries in Bilateral Supernova Remnants  

CERN Multimedia

AIMS: We investigate whether the morphology of bilateral supernova remnants (BSNRs) observed in the radio band is determined mainly either by a non-uniform interstellar medium (ISM) or by a non-uniform ambient magnetic field. METHODS: We perform 3-D MHD simulations of a spherical SNR shock propagating through a magnetized ISM. Two cases of shock propagation are considered: 1) through a gradient of ambient density with a uniform ambient magnetic field; 2) through a homogeneous medium with a gradient of ambient magnetic field strength. From the simulations, we synthesize the synchrotron radio emission, making different assumptions about the details of acceleration and injection of relativistic electrons. RESULTS: We find that asymmetric BSNRs are produced if the line-of-sight is not aligned with the gradient of ambient plasma density or with the gradient of ambient magnetic field strength. We derive useful parameters to quantify the degree of asymmetry of the remnants that may provide a powerful diagnostic of t...

Orlando, S; Reale, F; Peres, G; Petruk, O

2007-01-01

126

The supernova remnant in 30 Dor B  

International Nuclear Information System (INIS)

An optical counterpart of the radio/X-ray supernova remnant in 30 Dor B in the LMC has been detected by direct imaging and spectroscopic techniques. Interesting properties at X-ray, optical and radio wavelengths are considered. Because it has a non-thermal X-ray spectrum and a flat radio spectrum, it may be a Crab-like SNR, but more evolved. (author)

1981-01-01

127

X-rays from Supernova Remnants  

CERN Document Server

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

128

Detecting supernova remnants in external galaxies  

International Nuclear Information System (INIS)

The author discusses reliable identifications of supernova remnants in external galaxies are slowly becoming available through the combined use of radio, optical, and x-ray surveys. The host galaxies represent a variety of Hubble types. Although the number of SNR detected in each galaxy is currently small, new telescopes and detectors in all three wavelength regimes should allow us to obtain larger samples in the near future

1984-01-01

129

Spitzer Observations of Molecular Hydrogen in Interacting Supernova Remnants  

CERN Multimedia

With Spitzer IRS we have obtained sensitive low-resolution spectroscopy from 5 to 35 microns for six supernova remnants (SNRs) that show evidence of shocked molecular gas: Kes 69, 3C 396, Kes 17, G346.6-0.2, G348.5-0.0 and G349.7+0.2. Bright, pure-rotational lines of molecular hydrogen are detected at the shock front in all remnants, indicative of radiative cooling from shocks interacting with dense clouds. We find the excitation of H2 S(0)-S(7) lines in these SNRs requires two non-dissociative shock components: a slow, 10 km/s C- shock through clumps of density 10^6 cm^-3, and a faster, 40-70 km/s C- shock through a medium of density 10^4 cm^-3. The ortho-to-para ratio for molecular hydrogen in the warm shocked gas is typically found to be much less than the LTE value, suggesting that these SNRs are propagating into cold quiescent clouds. Additionally a total of thirteen atomic fine-structure transitions of Ar+, Ar++, Fe+, Ne+, Ne++, S++, and Si+ are detected. The ionic emitting regions are spatially segrega...

Hewitt, John W; Andersen, Morten; Reach, William T

2009-01-01

130

Supernova Ejecta in the Youngest Galactic Supernova Remnant G1.9+0.3  

Digital Repository Infrastructure Vision for European Research (DRIVER)

G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of about 1900, and most likely located near the Galactic Center. Only the outermost ejecta layers with free-expansion velocities larger than about 18,000 km/s have been shocked so far in this dynamically young, likely Type Ia SNR. A long (980 ks) Chandra observation in 2011 allowed spatially-resolved spectroscopy of heavy-element ejecta. We denoised Chandra data w...

Borkowski, K. J.; Reynolds, S. P.; Hwang, U.; Green, D. A.; Petre, R.; Krishnamurthy, K.; Willett, R.

2013-01-01

131

Influence of an Internal Magnetar on Supernova Remnant Expansion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Most of the proposed associations between magnetars and supernova remnant suffer from age problems. Usually, supernova remnants ages are determined from an approximation of the Sedov-Taylor phase relation between radius and age, for a fixed energy of the explosion ~ 10^{51} erg. Those ages do not generally agree with the characteristic ages of the (proposed) associated magnetars. We show quantitatively that, by taking into account the energy injected on the supernova remnant...

Allen, M. P.; Horvath, J. E.

2003-01-01

132

Supernova Remnants in the Magellanic Clouds; 3, An X-ray Atlas of LMC Supernova Remnants  

CERN Document Server

We have used archival ROSAT data to present X-ray images of thirty-one supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). We have classified these remnants according to their X-ray morphologies, into the categories of Shell-Type, Diffuse Face, Centrally Brightened, Point-Source Dominated, and Irregular. We suggest possible causes of the X-ray emission for each category, and for individual features of some of the SNRs.

Williams, R M; Dickel, J R; Petre, R; Smith, R C; Tavarez, M; Williams, Rosa Murphy; Chu, You-Hua; Dickel, John R.; Petre, Robert; Tavarez, Maritza

1999-01-01

133

High-resolution X-ray spectral diagnostics of shell type supernova remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Supernova remnants are at the nexus of many important, comtemporary, astrophysical problems: the late stage of stellar evolution, supernovae, the formation of compact objects, nucleosynthesis, collisionless shocks, particle acceleration and possibly gamma-ray bursts. The major focus of this thesis is on the thermal X-ray emission. This is an important part of SNR studies as most of the initial mechanical energy is radiated as thermal X-ray emission. The shocked environment and the ...

Heyden, Kurt Josias

2004-01-01

134

Three Supernova Remnants observed by BeppoSAX  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the results of three observations of shell-type supernova remnants observed by BeppoSAX. Two of the remnants (N132D and Cas A) are oxygen rich supernova remnants. They were observed during the PV phase. SN1006 was observed during A01. For SN1006 we present preliminary results on the abundance measurements based on the emission from the center of the remnant.

Vink, Jacco

1998-01-01

135

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

I determine the expansion of the supernova remnant of SN1604 (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 as $r \\propto t^{0.5}$, but there are significant differences in different parts of the remnant: the bright northwestern part ...

Vink, J.

2008-01-01

136

Exploring the Kinematics of the Oxygen-Rich Supernova Remnant G292.0+1.8: Ejecta Shells, Fast-Moving Knots and Shocked Circumstellar Material  

CERN Document Server

We present results of an in-depth optical study of the core collapse supernova remnant G292.0+1.8 using the Rutgers Fabry-Perot (RFP) imaging spectrometer. Our observations provide a detailed picture of the supernova remnant in the emission lines of [O III] 5007, Halpha and [N II] 6548. The [O III] Fabry-Perot scans reveal a bright crescent-shaped spur of previously known high-velocity (V_radial ~ 1500 km/s) O-rich ejecta located on the eastern side of the remnant. The spur consists of a semi-coherent structure of mostly redshifted material, along with several clumps that have apparently broken out of the more orderly shell-like expansion. The high velocity (>= 600 km/s) component of the spur also displays a scalloped morphology characteristic of Rayleigh-Taylor instabilities. We also find a large number of fast-moving knots (FMKs) of O-rich ejecta undetected in prior photographic plate images and similar to features seen in Cas A. The position-velocity distribution of the FMKs can be kinematically described ...

Ghavamian, P; Willliams, T B; Ghavamian, Parviz; Hughes, John P.

2005-01-01

137

Evolution of multiple supernova remnants  

CERN Document Server

Heating of the interstellar medium by multiple supernovae (SNe) explosions is at the heart of producing galaxy-scale outflows in starburst galaxies. Standard models of outflows assume a high efficiency of SNe in heating the gas to X-ray emitting temperatures and to fill the central region of starburst with hot gas, in order to launch vigorous outflows. We study the efficiency of multiple SNe in heating the interstellar medium (ISM) and filling the volume with gas of high temperatures, with 2-D and 3-D hydrodynamic simulations. We argue that SNe have to be clustered in space and time (and be coherent) in order to compensate for the radiative loss. In particular, we find that in coherent cases, the filling factor of gas with $3 \\times 10^6$ K can be at the most $\\le 0.3$ and the total heating efficiency $\\le 0.3$, for gas with density $1$ cm$^{-3}$ and $0.1\\hbox{--}1$ Z$_\\odot$. The heating efficiency and filling factors are much smaller in incoherent cases. Comparing our results to the commonly adopted efficie...

Vasiliev, Evgenii O; Bondarev, Roman; Shchekinov, Yuri

2014-01-01

138

Cosmic ray acceleration and escape from supernova remnants  

CERN Multimedia

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

139

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

140

ASYMMETRIES IN THE EXPANSION AND EMISSION FROM YOUNG SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

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

 
 
 
 
141

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

142

An X-ray study of the Monoceros supernova remnant  

International Nuclear Information System (INIS)

Twelve Einstein IPC exposures within the region of the Monoceros supernova remnant are combined into a 0.2-4keV X-ray map with 80 arcsec resolution. The X-ray bright regions correlate well with the bright optical filaments. From the IPC pulse height spectra, the bright regions are found to have a 2-6 keV high-temperature component, while all regions show a fainter 0.2-0.3 keV temperature component. A model with the supernova shock wave expanding into a three-component interstellar medium with a low-density (0.003cm"-"3) hot component can fit the observed properties of Monoceros. Preferred values for the distance and age are 1500pc and 3 x 10"4yr. (author)

1986-05-15

143

Non-thermal acceleration mechanisms in supernova remnant shells  

CERN Document Server

A review of the main issues in the field of particle acceleration in Supernova Remnants is provided in the context of future X-ray observations with Simbol-X. After a summary of the nonthermal acceleration mechanisms at work, I briefly review the observations of supernova remnants in hard X-rays and in gamma rays. Open issues are discussed in this framework.

Decourchelle, Anne

2008-01-01

144

The X-ray Spectrum of Supernova Remnant 1987A  

CERN Multimedia

We discuss the X-ray emission observed from Supernova Remnant 1987A with the Chandra X-ray Observatory. We analyze a high resolution spectrum obtained in 1999 October with the high energy transmission grating (HETG). From this spectrum we measure the strengths and an average profile of the observed X-ray lines. We also analyze a high signal-to-noise ratio CCD spectrum obtained in 2000 December. The good statistics (~ 9250 counts) of this spectrum and the high spatial resolution provided by the telescope allow us to perform spectroscopic analyses of different regions of the remnant. We discuss the relevant shock physics that can explain the observed X-ray emission. The X-ray spectra are well fit by plane parallel shock models with post-shock electron temperatures of ~ 2.6 keV and ionization ages of ~ 6 x 10^10 cm^3/s. The combined X-ray line profile has a FWHM of ~ 5000 km/s, indicating a blast wave speed of ~ 3500 km/s. At this speed, plasma with a mean post-shock temperature of ~ 17 keV is produced. This is ...

Michael, E; McCray, R; Hwang, U; Burrows, D N; Park, S; Garmire, G P; Holt, S S; Hasinger, G; Michael, Eli; Zhekov, Svetozar; Cray, Richard Mc; Hwang, Una; Burrows, David N.; Park, Sangwook; Garmire, Gordon P.; Holt, Stephen S.; Hasinger, Guenther

2002-01-01

145

Numerical Simulations of Dust Destruction in Supernova Remnants  

Science.gov (United States)

We investigate the destruction of newly-formed dust grains by sputtering in the reverse shocks of supernova remnants through hydrodynamic simulations.  Using an idealized setup of planar shock impacting a dense, spherical clump, we implant a population of Lagrangian particles into the clump to represent a distribution of dust grains, then post-process the simulation output to calculate the grain sputtering for a variety of species and size distributions. We explore the parameter space appropriate for this problem by altering the over-density of the ejecta clump, the density profile of the clump, and the speed of the reverse shock. Since radiative cooling could lower the temperature of the medium in which the dust is embedded and potentially protect the dust by slowing or halting grain sputtering, we study the effects of different cooling methods over the time scale of the simulations.  We also consider the influence of increased projectile mass on sputtering yields in metal-enriched plasmas. In general, results indicate that grains with radii less than 0.1 microns are sputtered to much smaller radii and often destroyed completely, while larger grains tend to survive their interaction with the reverse shock. The survival rate of grains formed by supernovae in the early universe is crucial in determining whether or not they can act as the "dust factories” needed to explain high-redshift dust mass estimates.

Silvia, Devin W.; Smith, B. D.; Shull, J. M.

2010-01-01

146

Excess gamma rays from the Loop I supernova remnant  

International Nuclear Information System (INIS)

Evidence is presented for an excess of cosmic ray intensity within the Loop I supernova remnant based on an interpretation of the observed distribution of gamma-rays across the remnant and the column densities of the associated gas. A strong case can thus be made for the bulk of the cosmic radiation (E , 10 to the 11th power eV) being produced in the Galactic supernova remnants

1985-08-01

147

Thermonuclear supernova explosions and their remnants: the case of Tycho  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose to use the thermal X-ray emission from young supernova remnants (SNRs) originated in Type Ia supernovae (SNe) to extract relevant information concerning the explosion mechanism. We focus on the differences between numerical 1D and 3D explosion calculations, and the impact that these differences could have on young SNRs. We use the remnant of the Tycho supernova (SN 1572) as a test case to compare with our predictions, discussing the observational features that all...

Badenes, Carles; Bravo, Eduardo; Borkowski, Kazimierz J.

2003-01-01

148

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

149

Chandra LETG Observations of Supernova Remnant 1987A  

CERN Multimedia

We discuss the results from deep Chandra LETG observations of the supernova remnant 1987A (SNR 1987A). We find that a distribution of shocks, spanning the same range of velocities (from 300 to 1700 km/s) as deduced in the first part of our analysis (Zhekov et al. 2005, ApJL, 628, L127), can account for the entire X-ray spectrum of this object. The post-shock temperature distribution is bimodal, peaking at kT 0.5 and 3 keV. Abundances inferred from the X-ray spectrum have values similar to those for the inner circumstellar ring, except that the abundances of nitrogen and oxygen are approximately a factor of two lower than those inferred from the optical/UV spectrum. The velocity of the X-ray emitting plasma has decreased since 1999, apparently because the blast wave has entered the main body of the inner circumstellar ring.

Zhekov, S A; Burrows, D N; McCray, R; Park, S; Borkowski, Kazimierz J.; Burrows, David N.; Cray, Richard Mc; Park, Sangwook; Zhekov, Svetozar A.

2006-01-01

150

Supernova remnants, pulsar wind nebulae and their interaction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A supernova explosion marks the end of the evolution of a massive star. What remains of the exploded star is a high density neutron star or a black hole. The material which has been ejected by the supernova explosion will manifest itself as a supernova remnant: a hot bubble of gas expanding in the interstellar medium.

Swaluw, E.

2001-01-01

151

Infrared [Fe II] and Dust Emissions from Supernova Remnants  

Science.gov (United States)

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 H2 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]-H2 reversal'' in SNRs and on using the [Fe II]-line luminosity as an indicator of the supernova (SN) rate in galaxies. In the mid- and far-infrared regimes, thermal dust emission is dominant. The dust in SNRs can be heated either by collisions with gas species in a hot plasma or by radiation from a shock front. I discuss the characteristics of the infrared morphology of the SNRs interacting with molecular clouds and their dust heating processes. Finally, I give a brief summary of the detection of SN dust and crystalline silicate dust in SNRs.

Koo, Bon-Chul

2014-01-01

152

Detecting X-ray Synchrotron Emission in Supernova Remnants Implications for Abundances and Cosmic Rays  

CERN Document Server

The 10^51 ergs released in a supernova have far reaching consequences in the galaxy, determining elemental abundances, accelerating cosmic rays, and affecting the makeup of the interstellar medium. Recently the spectra of several supernova remnants have been found to be dominated by nonthermal emission. Separating the thermal and nonthermal components is important not only for the understanding of cosmic-ray acceleration and shock microphysics properties but for accurate assessment of the temperatures and line strengths. New models designed to model spatially resolved synchrotron X-rays from type Ia supernovae can contribute to the understanding of both the thermal physics (dynamics, abundances) and nonthermal physics (shock acceleration, magnetic-field amplification) of supernova remnants. I will describe model fits to SN 1006, emphasizing the physical constraints that can be placed on SNRs, abundances, and the cosmic-ray acceleration process.

Dyer, K K; Borkowski, K J; Petre, R; Dyer, Kristy K.; Reynolds, Stephen P; Borkowski, Kazik J.; Petre, Robert

2000-01-01

153

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

154

Infrared [Fe II] and Dust Emissions from Supernova Remnants  

CERN Document Server

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

155

Models for X-ray emission from the A. D. 1006 supernova remnant  

International Nuclear Information System (INIS)

The recently detected X-ray emission from the remnant of the A.D. 10006 supernova is interpreted in terms of blast wave and reverse shock models. I find that while either model can provide a consistent explanation for the observations, the reverse shcok description leads to more reasonable values for the interstellar density and blast energy. Interestingly, both models indicate a distance of about 1.2 kpc for the remnant

1977-01-15

156

Eruption of supernova shock waves  

International Nuclear Information System (INIS)

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

157

Spectral turnovers of galactic supernova remnants  

International Nuclear Information System (INIS)

High-resolution observations of 14 galactic supernova remnants have been made at 80 and 160 MHz with the Culgoora radioheliograph. The spectra of 7 to 10 of the sources exhibit a turnover at approximately-less-than100 MHz which we attribute to free-free absorption taking place in the inner regions of the Galaxy. The absorption could occur in large (approximately-greater-than20 pc), low-density (napprox. =10 cm-3) Hii regions created by O5 to O8 stars. Alternatively, absorption could occur in cold dense clouds which are a feature of the steady-state model of the interstellar medium, or, more likely, in cold, partly ionized regions of moderate density which are a feature of the time-dependent model. (auth)

1975-07-01

158

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

159

Limits on Enhanced Radio Wave Scattering by Supernova Remnants  

CERN Document Server

We report multifrequency observations with the NRAO Very Long Baseline Array (VLBA) of the compact radio sources J0128+6306 and J0547+2721, which are viewed through the supernova remnants G127.1+0.5 and S147, respectively. Observations were made at frequencies of 1.427, 1.667, 2.271, and 4.987 GHz. The lines of sight to these sources pass through the shock wave and upstream and downstream turbulent layers of their respective supernova remnants, and thus might detect cosmic-ray generated turbulence produced during the Fermi acceleration process. For both sources, we detect interstellar scattering, characterized by a component of the angular size which scales as the square of the observing wavelength. The magnitude of the scattering is characterized by an effective scattering angular size theta_S0 at a frequency of 1 GHz of 13.2 +/- 2.6 milliarcseconds (mas) for J0128+6306 and 6.7 +/- 2.2 mas for J0547+2721. These angular sizes are consistent with the ``incidental'' scattering for any line of sight out of the g...

Spitler, L G; Spitler, Laura G.; Spangler, Steven R.

2005-01-01

160

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

 
 
 
 
161

A multiwavelength study of Cassiopeia A and Kepler's supernova remnants  

Science.gov (United States)

A multiwavelength comparison of X-ray, infrared, optical, and radio images for Cassiopeia A (Cas A) and Kepler's supernova remnants has been conducted to construct a coherent physical picture of the multiple interacting thermal and relativistic plasmas. In addition, high- resolution X-ray proper motions of compact features in Cas A have been measured over a two-year baseline. The X-ray emission in Cas A can be separated into four spectrally and kinematically distinct classes that have clear associations to the emission in the other three wavebands. The emitting material is classified into two components—shocked circumstellar medium (CSM) and shocked ejecta, which show the same respective morphologies and proper motions in the different bands. In the shocked CSM, we find matched low-energy enhanced X-ray emission and optical quasi-stationary flocculi, and X-ray continuum-dominated emission matched with filamentary radio structures. We also find hybrid X-ray low-energy-enhanced/continuum-dominated emission matched to 24?m dust emission in the CSM. In the shocked ejecta, we find matched silicon and iron dominated X-ray emission and optical fast-moving knots. Based on the kinematic and morphological results, we propose evolutionary scenarios for the ejecta and circumstellar material in Cas A. In Kepler's supernova remnant, we also find clear associations between the emission in the four wavebands. The ejecta are defined by matching steep-spectrum radio emission and X-ray emission. The forward shock is identified by a ring of continuum-dominated X-ray emission, flat-spectrum radio emission, and filamentary optical Balmer-dominated emission. The clumpy circumstellar medium is identified by knotty optical emission, mid-infrared dust emission, and some matching X-ray emission. To the south the forward and reverse shocks have separated, whereas to the north there is little separation. There is an anti-correlation between the flat-spectrum radio synchrotron emission and the thermal emission to the north suggesting a relative weakening of the particle acceleration at the forward shock due to Alvén wave damping.

Delaney, Tracey Ann

162

Study on a faint nebula - the HB3 supernova remnant  

International Nuclear Information System (INIS)

Hsub(?) interferometric observations of the Supernova remnant HB3 have been carried out. A contrast Fabry-Perot interferometer in conjunction with an electronic image converter, placed in the Cassegrain foci of the 125-cm and 48-cm reflectors, was used. The gas motions in the remnant have been studied. The outflow velocity of the most rapidly moving gas masses corresponds to the shock front velocity Vsub(s)=200-250 km/sec. The velocity of the radiative wave in dense gas clouds, responsible for the emission of optical filaments, is 35-50 km/sec. The mean radial velocity of the object, Vsub(LSR), is found to be -45+-3 km/sec, the corresponding kinematic distance is 3+-0.2 kpc, the linear radius of the envelope is 41 pc. The energetics of the remnant and its association with the W3-W4-W5 complex, the well-known star formation region, are discussed

1980-01-01

163

Observation of the Supernova Remnant IC 443 with VERITAS  

CERN Multimedia

Shell-type supernova remnants (SNRs) accelerate particles at the shock front between the expanding remnant and the swept-up interstellar medium. If these particles include protons and nuclei, very-high-energy gamma-ray emission may result from the decay of pions produced in interactions between cosmic rays and the local insterstellar medium. For SNRs that are interacting with a nearby molecular cloud, such as IC 443, the enhanced matter density provides a target medium that can amplify the gamma-ray emission. IC 443 also contains the pulsar wind nebula (PWN) CXOU J061705.3+222127. PWNe are the most plentiful galactic sources of very-high-energy gamma rays, which are produced in the shock formed at the collision of the pulsar wind with the ambient medium. VERITAS is an array of four 12-m telescopes dedicated to gamma-ray astronomy in the energy band above 100 GeV. Located on Mt. Hopkins in southern Arizona, VERITAS operated during the 2006-2007 season in 2-, 3-, and 4-telescope observation modes. In this talk,...

Humensky, T B

2007-01-01

164

Onion-shell model of cosmic ray acceleration in supernova remnants  

Science.gov (United States)

A method is devised to approximate the spatially averaged momentum distribution function for the accelerated particles at the end of the active lifetime of a supernova remnant. The analysis is confined to the test particle approximation and adiabatic losses are oversimplified, but unsteady shock motion, evolving shock strength, and non-uniform gas flow effects on the accelerated particle spectrum are included. Monoenergetic protons are injected at the shock front. It is found that the dominant effect on the resultant accelerated particle spectrum is a changing spectral index with shock strength. High energy particles are produced in early phases, and the resultant distribution function is a slowly varying power law over several orders of magnitude, independent of the specific details of the supernova remnant.

Bogdan, T. J.; Volk, H. J.

1983-01-01

165

Spallative Nucleosynthesis in Supernova Remnants; 1, Analytical Estimates  

CERN Multimedia

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

166

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

CERN Document Server

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

167

HST/ACS Narrowband Imaging of the Kepler Supernova Remnant  

Science.gov (United States)

We present narrowband images of the Kepler supernova remnant obtained with the Advanced Camera for Surveys aboard the Hubble Space Telescope. The images, with an angular resolution of 0.05" reveal the structure of the emitting gas in unprecedented detail. Radiative and nonradiative shocks are found in close proximity, unresolvable in gromd-based spectra, indicating that the pre-shock medium is highly clumped. The ionization structure, traced by differences in the [0 111] to [N 11] flux ratio, varies on subarcsecond scales. The variation is due to 110th differences in shock velocity as well as gradients in the evolutionary stage of the shocks. A prollinent complex of knots protruding beyond the boundary of the rennallt in the northwest is found to consist of bright radiative knots, collected by arcuate nonradiative filaments. Based on the coincidence of the optical emission with a bright isolated knot of X-ray emission, we infer that this feature is due to a Rayleigh-Taylor finger that formed at the contact discontinuity and overtook the primary blast wave.

Sankrit, Ravi; Blair, William P.; Frattare, Lisa M.; Rudnick, Lawrence; DeLaney, Tracey; Harrus, Ilana M.; Ennis, Jessica A.

2007-01-01

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

Dust in a Type Ia Supernova Progenitor: Spitzer Spectroscopy of Kepler's Supernova Remnant  

Science.gov (United States)

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 micron IR spectra of the remnant, obtained with the Spitzer Space Telescope, dominated by emission from warm dust. Broad spectral features at 10 and 18 micron, consistent with various silicate particles, are seen throughout. These silicates were likely formed in the stellar outflow from the progenitor system during the AGB 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 IRS and IRAC 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) 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) into moderate density material (n(sub o) approx 50-100 / cubic cm) 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; Reynolds, Stephen P.; Ghavamian, Parviz; Blair, William P.; Long, Knox S.; Sankrit, Ravi

2012-01-01

170

Far Ultraviolet Spectroscopic Explorer Survey of Magellanic Cloud Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 o...

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

2006-01-01

171

Optical spectrum of the unusual supernova remnant G109.1 - 1.0  

International Nuclear Information System (INIS)

Similarities in the x-ray and radio spectra of the new supernova remnant G109.1 - 1.0 and the SS433 - W50 pair have been investigated. A spectrum of the faint optical filaments associated with the large shell-like radio source has been obtained showing strong [S II] lambdalambda 6,717,6,731 emission relative to H?, which is characteristic of shock-heated gas and which confirms that the filaments are part of the supernova remnant, and is generally similar to spectra of the Cygnus Loop. By assuming pressure equilibrium between the optical filaments and the interior of the remnant an initial energy of 3 x 1051 erg is found, which is higher than that found from x-ray measurements. When compared with W50, the G109.1 - 1.0 remnant has filaments of higher density, and weaker [N II] emission. (U.K.)

1981-05-14

172

High-velocity gas associated with the supernova remnant S147  

International Nuclear Information System (INIS)

The star HD 36665, which lies behind the old supernova remnant S 147, has been observed with the IUE satellite. High-velocity interstellar absorption components of Fe II, Mg I, Mg II, Al II, C II and Si II were detected which originate in gas associated with the remnant. No such high-velocity lines were observed in the IUE spectrum of HD 40111 which is offset from the remnant. The high-velocity ultraviolet lines, together with new ground-based observations of high-velocity Ca II in HD 36665, have been analysed to determine column densities and to estimate the physical conditions in the high-velocity gas. The estimated level of depletions in the high-velocity gas is somewhat less than that normally observed in low-velocity interstellar gas, suggesting that sputtering of grains has occurred in the shock front of the supernova remnant. (author)

1981-01-01

173

X-ray emission of the hot gas and of accelerated particles in supernova remnants  

International Nuclear Information System (INIS)

The current observations seem to support the theory that the shock wave of supernova remnants accelerate electrons (representing about 1% of cosmic rays) of the interstellar medium up to energies of about 1015 eV. However there is still no solid evidence that supernova remnants also accelerate protons (major component of cosmic rays). The X-ray observations of those supernova remnants with the satellite XMM-Newton can provide crucial information on the acceleration mechanisms and on this population of accelerated particles. This thesis presents the X-ray analysis of the supernova remnants RX J1713.7-3946 and SN 1006 for which it has been shown that they accelerate electrons efficiently. As a result, these objects are very good targets to compare the theoretical models of acceleration to the observation. For the first object, I constructed through new XMM-Newton observations, the first high-angular resolution mosaic of the entire supernova remnant. I then compared the X- and gamma-ray emission of this object in order to understand the nature of the gamma-ray emission. This spectral and morphological comparison allowed me to discuss the two possible origins of the gamma-ray radiation (issued by electrons or by protons). For SN 1006, I studied the density of the ambient medium in which the shock wave propagates. This density is a key parameter for the hydrodynamical evolution of the remnant and for studying a future gamma-ray emission. The study of X-ray emission of the gas heated by the shock wave allowed me to better estimate of the value of the density so far poorly constrained for this object. (author)

2008-01-01

174

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 signi...

Williams, R. M.; Chu, Y. -h

2005-01-01

175

Five Years in the Mid-Infrared Development of the SN 1987A Supernova Remnant  

Science.gov (United States)

Spitzer has been used to monitor the mid-IR evolution of SN 1987A over a 5 year period as it develops into a supernova remnant through interaction with its surrounding environment. This interaction is dominated by the collision of the ejecta with the pre-existing equatorial ring. The mid-IR continuum indicates an increasing mass of shock-heated silicate dust, but without any significant change in temperature of the dust grains. Comparison of the IR and X-ray evolution of the remnant can be used to infer plasma conditions and the processing of the dust in the shock-heated X-ray emitting gas.

Dwek, Eliahu

2009-01-01

176

Water, Hydroxyl and Carbon Monoxide Emission in Molecular Supernova Remnants with Herschel  

Science.gov (United States)

We present Herschel observations of supernova remnants (SNRs) that are interacting with molecular clouds using PACS, SPIRE and HIFI. Dense clouds behind strong supernova shocks are astrochemical laboratories to study formation or dissociation of various molecules to probe the effect of high energy emission, precursors, or dust processing. Herschel spectra revealed rich molecular lines of high-J and low-J carbon monoxide, water, hydroxyl and a few atomic lines of oxygen and nitrogen. We observed three SNRs and there is some variation in detections SNR by SNR. We will compare shock and pre-existing molecular properties to understand formation of molecules and their interplay of different molecules, present CO excitation diagrams, and distinguish the shock conditions using various shock models. The shock physical conditions will be compared with those derived from molecular hydrogen lines. We will discuss the abundances of CO, water and OH and astrochemical processes of molecules behind dense molecular shocks.

Rho, Jeonghee; Hewitt, J. W.

2014-01-01

177

Permitted O_I line emission from oxygen nebulosities of supernova remnants  

International Nuclear Information System (INIS)

The O_I 7774 and 8446 A line emission from fast-moving oxygen nebulosities of Puppis A and Cassiopeia A is much weaker than that predicted by models for a steady shock wave in a pure oxygen gas. In the models, these lines result from recombination in the photoionized tail of the wave. We argue that the postshock flow in the oxygen-dominated supernova ejecta may be nonsteady and truncated in the tail, as has been proposed for shocked interstellar clouds in the Cygnus Loop and the Vela supernova remnants. (author)

1986-01-01

178

Supernova Remnant Progenitor Masses in M31  

CERN Document Server

Using HST photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main sequence masses (MZAMS) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and use CMD fitting to measure the recent star formation history (SFH) of the regions surrounding cataloged SNR sites. We identify any young coeval population that likely produced the progenitor star and assign an age and uncertainty to that population. Application of stellar evolution models allows us to infer the MZAMS from this age. Because our technique is not contingent on precise location of the progenitor star, it can be applied to the location of any known SNR. We identify significant young SF around 53 of the 59 SNRs and assign progenitor masses to these, representing a factor of 2 increase over currently measured progenitor masses. We consider the remaining 6 SNRs as either probable Type Ia candidates or the result of core-collapse progenitors that have escaped ...

Jennings, Zachary G; Murphy, Jeremiah W; Dalcanton, Julianne J; Gilbert, Karoline M; Dolphin, Andrew E; Fouesneau, Morgan; Weisz, Daniel R

2012-01-01

179

A Model Grid for the Spectral Analysis of X-ray Emission in Young Type Ia Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We address a new set of models for the spectral analysis of the X-ray emission from young, ejecta-dominated Type Ia supernova remnants. These models are based on hydrodynamic simulations of the interaction between Type Ia supernova explosion models and the surrounding ambient medium, coupled to self-consistent ionization and electron heating calculations in the shocked supernova ejecta, and the generation of synthetic spectra with an appropriate spectral code. The details ar...

Badenes, C.; Bravo, E.; Borkowski, K.

2005-01-01

180

Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 pe...

Shinn, Jong-ho; Min, Kyoung Wook; Sankrit, Ravi; Ryu, Kwang-sun; Kim, Il-joong; Han, Wonyong; Nam, Uk-won; Park, Jang-hyun; Edelstein, Jerry; Korpela, Eric J.

2007-01-01

 
 
 
 
181

Thermonuclear supernova explosions and their remnants: the case of Tycho  

CERN Multimedia

We propose to use the thermal X-ray emission from young supernova remnants (SNRs) originated in Type Ia supernovae (SNe) to extract relevant information concerning the explosion mechanism. We will focus on the differences between numerical 1D and 3D explosion calculations, and the impact that these differences could have on young SNRs. We use the remnant of the Tycho supernova (SN 1572) as a test case to compare with our predictions, discussing the observational features that allow to accept or discard a given model.

Badenes, C; Borkowski, K J; Badenes, Carles; Bravo, Eduardo; Borkowski, Kazimierz J.

2003-01-01

182

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

CERN Multimedia

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

183

Discovery of optical candidate supernova remnants in Sagittarius  

Science.gov (United States)

During an [O III] survey of planetary nebulae, we identified a region in Sagittarius containing several candidate supernova remants (SNRs) and obtained deep optical narrow-band images and spectra to explore their nature. We obtained images of the area of interest by acquiring observations in the emission lines of H? + [N II], [S II] and [O III]. The resulting mosaic covers an area of 1.4° × 1.0°, where both filamentary and diffuse emission was discovered, suggesting that there is more than one SNR 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 that they are related, while the infrared emission found in the area at 12 ?m and 22 ?m marginally correlates with the optical. The presence of the [O III] emission line in one of the candidate SNRs implies that the shock velocities in the interstellar "clouds" are between 120 km s-1 and 200 km s-1, while its absence in the other candidate SNRs indicates that the shock velocities there are slower. For all candidate remnants, the [S II] ?? 6716/6731 ratio indicates that the electron densities are below 240 cm-3, while the H? emission is measured to be between 0.6 and 41 × 10-17 erg s-1 cm-2 arcsec-2. The existence of eight pulsars within 1.5° of the center of the candidate SNRs also implies that there are many SNRs in the area as well as that the detected optical emission could be part of a number of supernovae explosions.

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

2012-08-01

184

Fermi-LAT Observations of Supernova Remnant Kesteven 79  

CERN Multimedia

In this paper we report on the detection of $\\gamma$-ray emission coincident with the Galactic supernova remnant Kesteven 79 (Kes 79). We analysed approximately 52 months of data obtained with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. Kes 79 is thought to be interacting with adjacent molecular clouds based on the presence of strong $^{12}$CO J = 1 $\\rightarrow$ 0 and HCO$^{+}$ J = 1 $\\rightarrow$ 0 emission and the detection of 1720 MHz line emission towards the east of the remnant. Acceleration of cosmic rays is expected to occur at SNR shocks, and SNRs interacting with dense molecular clouds provide a good testing ground for detecting and analysing the production of $\\gamma$-rays from the decay of $\\pi^0$ into two $\\gamma$-ray photons. This analysis investigates $\\gamma$-ray emission coincident with Kes 79, which has a detection significance of $\\sim 7 \\sigma$. Additionally we present an investigation of the spatial and spectral characteristics of Kes 79 using multiple arc...

Auchettl, Katie; Castro, Daniel

2014-01-01

185

Particle Acceleration in Supernova Remnants and Pulsar Wind Nebulae  

CERN Multimedia

While supernova remnants (SNRs) have long been considered prime candidates for the source of cosmic rays, at least to energies up to ~10^14 eV, it is only over the past several years that direct evidence of such energetic particles in SNRs has been uncovered. X-ray observations of several shell-type SNRs have now revealed sites dominated by nonthermal emission, indicating an electron population whose energy extends far beyond the thermal distribution typical of such SNRs. In other remnants, discrepancies between the shock velocity and the electron temperature points to a strong cosmic ray component that has essentially thrived at the expense of the thermal component of the gas. Modeling of the radio, X-ray, and gamma-ray emission provides strong constraints on the acceleration mechanism as well as the properties of the ambient medium in which the mechanism prospers. In the innermost regions of some SNRs, particle acceleration is taking place over much different scales. The formation of Crab-like pulsar wind n...

Slane, P O

2002-01-01

186

Dynamics of Fe-Ni Bubbles in Young Supernova Remnants  

CERN Multimedia

Observations of core-collapse supernovae (SNe) have revealed the presence of extensive mixing of radioactive material in SN ejecta. The mixing of radioactive material, mostly freshly synthesized Ni, is not complete, which leads to a two-phase SN ejecta structure. The low-density phase consists of Fe bubbles, created by the energy input from radioactive Co and Ni, surrounded by compressed high-density metal-rich ejecta. We report on the theoretical investigation of supernova remnant (SNR) dynamics with the two-phase SN ejecta. We first present 3-dimensional hydrodynamic simulations of a single Fe bubble immersed in an outer ejecta envelope, and compare the results with previous work on shock-cloud interactions. We then consider randomly distributed Fe bubbles with an average volume filling fraction of 1/2. We find that the presence of Fe bubbles leads to vigorous turbulence and mixing of Fe with other heavy elements and with the ambient normal-abundance gas. The turbulent energy can be an order of magnitude la...

Blondin, J M; Reynolds, S P

2001-01-01

187

IS THERE A HIDDEN HOLE IN TYPE Ia SUPERNOVA REMNANTS?  

International Nuclear Information System (INIS)

In this paper, we report on the bulk features of the hole carved by the companion star in the material ejected during a Type Ia supernova (SN Ia) explosion. In particular we are interested in the long-term evolution of the hole as well as in its fingerprint in the geometry of the supernova remnant (SNR) after several centuries of evolution, which is a hot topic in current SN Ia studies. We use an axisymmetric smoothed particle hydrodynamics code to characterize the geometric properties of the SNR resulting from the interaction of this ejected material with the ambient medium. Our aim is to use SNR observations to constrain the single degenerate scenario for SN Ia progenitors. Our simulations show that the hole will remain open during centuries, although its partial or total closure at later times due to hydrodynamic instabilities is not excluded. Close to the edge of the hole, the Rayleigh-Taylor instability grows faster, leading to plumes that approach the edge of the forward shock. We also discuss other geometrical properties of the simulations, like the evolution of the contact discontinuity.

2012-01-20

188

Dense molecular cloud impacted by the W28 supernova remnant  

International Nuclear Information System (INIS)

Molecular spectra and an infrared survey of a dense molecular cloud obscuring a part of the optical nebulosity associated with the supernova remnant W28 have been obtained. The spectra reveal a warm dense core in a region of substantial line broadening near a maximum of nonthermal radio emission from the remnant. A small (approx.2 km s-1) shift in the velocity of peak molecular emission also occurs in this region. No embedded infrared source capable of heating the cloud appears to be present. The cloud appears to have been impacted by the expanding supernova remnant. The cloud appears to be an ambient cloud only recently compressed and heated by the nearby remnant; no evidence for star formation has been found. The remarkably broad HCO+ lines found near the cloud core originate in a region of enhanced ionization in the cloud, quite possibly resulting from penetration of the cloud by energetic radiation from the remnant

1981-04-01

189

The Youngest Known X-Ray Binary: Circinus X-1 and Its Natal Supernova Remnant  

Science.gov (United States)

Because supernova remnants are short-lived, studies of neutron star X-ray binaries within supernova remnants probe the earliest stages in the life of accreting neutron stars. However, such objects are exceedingly rare: none were known to exist in our Galaxy. We report the discovery of the natal supernova remnant of the accreting neutron star Circinus X-1, which places an upper limit of t Chandra X-ray observation and new radio observations of Circinus X-1. Circinus X-1 produces type I X-ray bursts on the surface of the neutron star, indicating that the magnetic field of the neutron star is small. Thus, the young age implies either that neutron stars can be born with low magnetic fields or that they can rapidly become de-magnetized by accretion. Circinus X-1 is a microquasar, creating relativistic jets that were thought to power the arcminute-scale radio nebula surrounding the source. Instead, this nebula can now be attributed to non-thermal synchrotron emission from the forward shock of the supernova remnant. The young age is consistent with the observed rapid orbital evolution and the highly eccentric orbit of the system and offers the chance to test the physics of post-supernova orbital evolution in X-ray binaries in detail for the first time.

Heinz, S.; Sell, P.; Fender, R. P.; Jonker, P. G.; Brandt, W. N.; Calvelo-Santos, D. E.; Tzioumis, A. K.; Nowak, M. A.; Schulz, N. S.; Wijnands, R.; van der Klis, M.

2013-12-01

190

The First VLBI Image of the Young, Oxygen-Rich Supernova Remnant in NGC 4449  

CERN Document Server

We report on sensitive 1.4-GHz VLBI radio observations of the unusually luminous supernova remnant SNR 4449-1 in the galaxy NGC 4449, which gave us the first well-resolved image of this object. The remnant's radio morphology consists of two approximately parallel bright ridges, suggesting similarities to the barrel shape seen for many older Galactic supernova remnants or possibly to SN 1987A. The angular extent of the remnant is 65 x 40 mas, corresponding to (3.7 x 2.3) x 10^{18} (D/3.8 Mpc) cm. We also present a new, high signal-to-noise optical spectrum. By comparing the remnant's linear size to the maximum velocities measured from optical lines, as well as using constraints from historical images, we conclude that the supernova explosion occurred between ~1905 and 1961, likely around 1940. The age of the remnant is therefore likely ~70 yr. We find that SNR 4449-1's shock wave is likely still interacting with the circumstellar rather than interstellar medium.

Bietenholz, M F; Milisavljevic, D; Fesen, R A; Challis, P; Kirshner, R P

2010-01-01

191

Observations of young core collapse supernova remnants  

Science.gov (United States)

Studies of young remnants offer an opportunity to test theoretical models of stellar evolution, explosion models and nucleosynthesis, as well as our understanding of the compact objects in the centre of the exploded stars. The first part of the thesis involves observations of the Crab nebula. We have used photometric and spectroscopic observations to search for a faint halo around the visible nebula, that could carry the missing mass and kinetic energy of the nebula. No halo was found. In the photometric data due to psf contamination, and in the spectroscopic no fast velocity components were present. We have also used optical and IR photometry to check for variation in the emissivity and dynamic structure of the Crab pulsar wind nebula (PWN), to try to understand the nature of plerionic PWNe. There, we measured flux variations up to 20% in the IR and also shifting of the wisps with velocities up to 0.2c. We also showed that the nearby red knot moves in tandem with the Crab pulsar. The second part of the thesis, deals with photometric & spectroscopic observations of SN 1987A in the LMC. The aim of the project was to monitor the evolution of the outer rings (ORs) of SN 1987A. The fading of the ORs is consistent with recombination and cooling after the initial flash ionization by the supernova. From the spectroscopic data we measured the density and temperature in the ORs where we found temperatures of ~ 12,000 K for the [N II] gas, and ~ 25,000 K for the [O III]. Finally, from the [O II], and [S II] ratios we estimated electron densities of ~ 1,000 cm-3 and ~ 2,500 cm-3, respectively. From the evolution of H?, we argue that the highest density in the ORs could be 5,000 cm-3.

Tziamtzis, Anestis

192

The Imprint of Presupernova Winds on Supernova Remnant Evolution: Towards More Realistic Models for Type Ia Supernova Remnants and their Spectra  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Supernova remnants are usually analysed in the light of hydrodynamical models of the interaction of supernova ejecta with either a constant density ambient medium or a circumstellar medium produced by a constant presupernova wind. However, the ejection of energetic wind during the presupernova phase changes the ambient medium structure and, consequently, the early supernova remnant evolution. We have analysed the evolution of young remnants of type Ia supernovae, focusing on...

Badenes, C.; Bravo, E.

2002-01-01

193

Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3  

CERN Document Server

We present a measurement of the expansion and brightening of G1.9+0.3, the youngest Galactic supernova remnant, 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 supernova remnant increasing in flux, with implications for the physics of electron acceleration in shock waves

Carlton, A K; Reynolds, S P; Hwang, U; Petre, R; Green, D A; Krishnamurthy, K; Willett, R

2011-01-01

194

XMM-Newton observation of the Tycho Supernova Remnant  

CERN Multimedia

We present the observation of the Tycho supernova remnant obtained with the EPIC and RGS instruments onboard the XMM-Newton satellite. We compare images and azimuthally averaged radial profiles in emission lines from different elements (silicon and iron) and different transition lines of iron (Fe L and Fe K). While the Fe XVII L line and Si XIII K line images are globally spatially coincident, the Fe K emission clearly peaks at a smaller radius, indicating a higher temperature toward the reverse shock. This is qualitatively the profile expected when the reverse shock, after travelling through the outer power-law density profile, has entered the central plateau of the ejecta. The high energy continuum map has an overall smooth distribution, with a similar extent to the radio emission. Its radial profile peaks further out than the lines emission. Brighter and harder continuum regions are observed with a rough bipolar symmetry in the eastern and western edges. The spectral analysis of the southeastern knots supp...

Decourchelle, A; Audard, M; Aschenbach, B; Sembay, S; Rothenflug, R; Ballet, J; Stadlbauer, T; West, R G

2001-01-01

195

Sphericization of the remnants of an asymmetric supernova outburst in a homogeneous medium  

International Nuclear Information System (INIS)

Numerical calculations have been performed in the 1.5-dimensional hydrodynamics approximation to analyze the sphericization of a shock wave, initially asymmetric in both form and velocity, which is propagated through a homogeneous interstellar medium. Three different approaches to the problem are considered, with preference given to the snowplow model. The time scale for the shock to sphericize is determined for various ISM densities and explosion parameters. If the initial asymmetry is strong enough, then even when the shock has become spherical in shape a substantial difference will persist in the surface density at the pole and at the equator, possibly explaining features observed in the supernova remnant Cassiopeia A

1982-09-01

196

X-RAY EMISSION FROM STRONGLY ASYMMETRIC CIRCUMSTELLAR MATERIAL IN THE REMNANT OF KEPLER'S SUPERNOVA  

International Nuclear Information System (INIS)

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.

2013-02-10

197

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

198

Cygnus Superbubble as the remnant of a peculiar supernova  

International Nuclear Information System (INIS)

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"5"2--10"5"3 erg. Analysis of the light curve of the NGC 1058 supernova 1961v demonstrates that it represents a roughly-equal2 x 10"5"2 erg outburst of a supermassive (roughly-equal10"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

1982-11-01

199

SUPERNOVA REMNANT PROGENITOR MASSES IN M31  

Energy Technology Data Exchange (ETDEWEB)

Using Hubble Space Telescope photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main-sequence masses (M{sub ZAMS}) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and employ CMD fitting to measure the recent star formation history of the regions surrounding cataloged SNR sites. We identify any young coeval population that likely produced the progenitor star, then assign an age and uncertainty to that population. Application of stellar evolution models allows us to infer the M{sub ZAMS} from this age. Because our technique is not contingent on identification or precise location of the progenitor star, it can be applied to the location of any known SNRs. We identify significant young star formation around 53 of the 59 SNRs and assign progenitor masses to these, representing a factor of {approx}2 increase over currently measured progenitor masses. We consider the remaining six SNRs as either probable Type Ia candidates or the result of core-collapse progenitors that have escaped their birth sites. In general, the distribution of recovered progenitor masses is bottom-heavy, showing a paucity of the most massive stars. If we assume a single power-law distribution, dN/dM{proportional_to}M{sup {alpha}}, then we find a distribution that is steeper than a Salpeter initial mass function (IMF) ({alpha} = -2.35). In particular, we find values of {alpha} outside the range -2.7 {>=} {alpha} {>=} -4.4 to be inconsistent with our measured distribution at 95% confidence. If instead we assume a distribution that follows a Salpeter IMF up to some maximum mass, then we find that values of M{sub Max} > 26 are inconsistent with the measured distribution at 95% confidence. In either scenario, the data suggest that some fraction of massive stars may not explode. The result is preliminary and requires more SNRs and further analysis. In addition, we use our distribution to estimate a minimum mass for core collapse between 7.0 and 7.8 M{sub Sun }.

Jennings, Zachary G.; Williams, Benjamin F.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Fouesneau, Morgan; Weisz, Daniel R. [Department of Astronomy, University of Washington Seattle, Box 351580, WA 98195 (United States); Murphy, Jeremiah W. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Dolphin, Andrew E., E-mail: zachjenn@uw.edu, E-mail: adolphin@raytheon.com [Raytheon, 1151 East Hermans Road, Tucson, AZ 85706 (United States)

2012-12-10

200

Six Years of Chandra Observations of Supernova Remnants  

CERN Multimedia

We present a review of the first six years of Chandra X-ray Observatory observations of supernova remnants. From the official "first-light" observation of Cassiopeia A that revealed for the first time the compact remnant of the explosion, to the recent million-second spectrally-resolved observation that revealed new details of the stellar composition and dynamics of the original explosion, Chandra observations have provided new insights into the supernova phenomenon. We present an admittedly biased overview of six years of these observations, highlighting new discoveries made possible by Chandra's unique capabilities.

Hughes, M C W J P

2005-01-01

 
 
 
 
201

Simulations of Mixed Morphology Supernova Remnants With Anisotropic Thermal Conduction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We explore the role of anisotropic thermal conduction on the evolution of supernova remnants through interstellar media with a range of densities via numerical simulations. We find that a remnant expanding in a dense environment can produce centre-bright hard x-ray emission within 20 kyr, and centre-bright soft x-ray emission within 60 kyr of the supernova event. In a more tenuous environment, the appearance of a centre-bright structure in hard x-rays is delayed until about ...

Tilley, David A.; Balsara, Dinshaw S.; Howk, J. Christopher

2006-01-01

202

The supernova remnant W50 at 5 GHz  

International Nuclear Information System (INIS)

Observations of the supernova remnant W50, which contains SS 433 have been made at 5 GHz with the Effelsberg 100-m telescope. These are combined with previous results at 1.7 and 2.7 GHz to investigate the intrinsic linear polarization and the variation of spectral index across the source. The spectrum of W50 is typical for old shell remnants and shows no evidence for the injection of flat-spectrum fast particles from SS 433. (author)

1986-02-01

203

Time-Dependent Escape of Cosmic Rays from Supernova Remnants, and their Interaction with Dense Media  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Context. Supernova remnants (SNRs) are thought to be the main source of Galactic cosmic rays (CRs) up to the "knee" in CR spectrum. During the evolution of a SNR, the bulk of the CRs are confined inside the SNR shell. The highest-energy particles leave the system continuously, while the remaining adiabatically cooled particles are released when the SNR has expanded sufficiently and decelerated so that the magnetic field at the shock is no longer able to confine them. Particl...

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

2011-01-01

204

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 t...

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

2011-01-01

205

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 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...

Badenes, Carles

2010-01-01

206

Interaction of a Pulsar Wind with the Expanding Supernova Remnant  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent HST observations of the Crab Nebula show filamentary structures that appear to originate from the Rayleigh-Taylor (R-T) instability operating on the supernova ejecta accelerated by the pulsar-driven wind. In order to understand the origin and formation of the filaments in the Crab Nebula, we study the interaction of a pulsar wind with the uniformly expanding supernova remnant by means of numerical simulation. By performing two-dimensional numerical simulations, we fin...

Jun, Byung-il

1997-01-01

207

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

208

New Models for X-Ray Synchrotron Radiation from the Remnant of Supernova 1006 AD  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Galactic cosmic rays up to energies of around 10^15 eV are assumed to originate in supernova remnants (SNRs). The shock wave of a young SNR like SN 1006 AD can accelerate electrons to energies greater than 1 TeV, where they can produce synchrotron radiation in the X-ray band. A new model (SRESC) designed to model synchrotron X-rays from Type Ia supernovae can constrain values for the magnetic-field strength and electron scattering properties, with implications for the accele...

Dyer, K. K.; Reynolds, S. P.; Borkowski, K. J.

2000-01-01

209

Interstellar and Ejecta Dust in the Cas A Supernova Remnant  

Science.gov (United States)

Infrared continuum observations provide a means of investigating the physical composition of the dust in the ejecta and swept up medium of the Cas A supernova remnant (SNR). Using low-resolution Spitzer IRS spectra (5-35 ?m), and broad-band Herschel PACS imaging (70, 100, and 160 ?m), we identify characteristic dust spectra, associated with ejecta layers that underwent distinct nuclear burning histories. The most luminous spectrum exhibits strong emission features at ~9 and 21 ?m and is closely associated with ejecta knots with strong Ar emission lines. The dust features can be reproduced by magnesium silicate grains with relatively low Mg to Si ratios. Another dust spectrum is associated with ejecta having strong Ne emission lines. It has no indication of any silicate features and is best fit by Al2O3 dust. A third characteristic dust spectrum shows features that are best matched by magnesium silicates with a relatively high Mg to Si ratio. This dust is primarily associated with the X-ray-emitting shocked ejecta, but it is also evident in regions where shocked interstellar or circumstellar material is expected. However, the identification of dust composition is not unique, and each spectrum includes an additional featureless dust component of unknown composition. Colder dust of indeterminate composition is associated with emission from the interior of the SNR, where the reverse shock has not yet swept up and heated the ejecta. Most of the dust mass in Cas A is associated with this unidentified cold component, which is <~ 0.1 M ?. The mass of warmer dust is only ~0.04 M ?.

Arendt, Richard G.; Dwek, Eli; Kober, Gladys; Rho, Jeonghee; Hwang, Una

2014-05-01

210

TYPING SUPERNOVA REMNANTS USING X-RAY LINE EMISSION MORPHOLOGIES  

International Nuclear Information System (INIS)

We present a new observational method to type the explosions of young supernova remnants (SNRs). By measuring the morphology of the Chandra X-ray line emission in 17 Galactic and Large Magellanic Cloud SNRs with a multipole expansion analysis (using power ratios), we find that the core-collapse SNRs are statistically more asymmetric than the Type Ia SNRs. We show that the two classes of supernovae can be separated naturally using this technique because X-ray line morphologies reflect the distinct explosion mechanisms and structure of the circumstellar material. These findings are consistent with recent spectropolarimetry results showing that core-collapse supernovae explosions are intrinsically more asymmetric.

2009-11-20

211

The Neutron Star Born in the Antlia Supernova Remnant  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2013-01-01

212

Are the Models for Type Ia Supernova Progenitors Consistent with the Properties of Supernova Remnants?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We explore the relationship between the models for progenitor systems of Type Ia supernovae and the properties of the supernova remnants that evolve after the explosion. Most models for Type Ia progenitors in the single degenerate scenario predict substantial outflows during the presupernova evolution. Expanding on previous work, we estimate the imprint of these outflows on the structure of the circumstellar medium at the time of the supernova explosion, and the effect that ...

Badenes, Carles; Hughes, John P.; Bravo, Eduardo; Langer, Norbert

2007-01-01

213

Are the models for type Ia supernova progenitors consistent with the properties of supernova remnants?,  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We explore the relationship between the models for progenitor systems of Type Ia supernovae and the properties of the supernova remnants that evolve after the explosion. Most models for Type Ia progenitors in the single-degenerate scenario predict substantial outflows during the presupernova evolution. Expanding on previous work, we estimate the imprint of these outflows on the structure of the circumstellar medium at the time of the supernova explosion, and the effect that this m...

Badenes, C.; Hughes, J. P.; Bravo, E.; Langer, N.

2007-01-01

214

Tests for supernova explosion models: from light curves to X-ray emission of supernova remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The successful theoretical supernova explosion models should be able to explain any features of the emission from supernovae at any evolutionary stage. We check several models from two different points of view. With the multi-frequency radiation hydro code STELLA we calculate gamma-ray, bolometric and broad-band UBVI light curves. Then we use the same models to calculate the emission from young supernova remnants. Here we present new plots for gamma-ray luminosity from seve...

Sorokina, Elena; Blinnikov, Sergey

2003-01-01

215

Generation of Seed Magnetic Fields in Primordial Supernova Remnants  

CERN Multimedia

Origin of the magnetic field ubiquitous in the Universe is studied based on the Biermann mechanism, which is expected to work in the non-barotropic region. We perform a series of two-dimensional MHD simulations of the first generation supernova remnant (SNR) expanding in the inhomogeneous interstellar matter (ISM) and study the Biermann mechanism working in the interior of the SNR. Especially, we pay attention to the relaxation process of electron and ion temperatures via the Coulomb interaction. In the early SNR in which the electron temperature is much lower than the ion temperature, the Biermann mechanism is ineffective, since the gradient of electron pressure is small. Magnetic fields begin to be generated just behind the shock front when the electron temperature is sufficiently relaxed. Assuming the explosion energy of 10^52 erg, the total magnetic energy generated reaches about 10^26 erg and does not depend strongly on the parameters of either SNR or ISM. Analytic expression to estimate the magnetic tot...

Hanayama, Hidekazu; Tomisaka, Kohji

2009-01-01

216

Is there a hidden hole in Type Ia supernova remnants?  

CERN Document Server

In this paper we report on the bulk features of the hole carved by the companion star in the material ejected during a Type Ia supernova explosion. In particular we are interested in the long term evolution of the hole as well as in its fingerprint in the geometry of the supernova remnant after several centuries of evolution, which is a hot topic in current Type Iasupernovae studies. We use an axisymmetric smoothed particle hydrodynamics code to characterize the geometric properties of the supernova remnant resulting from the interaction of this ejected material with the ambient medium. Our aim is to use supernova remnant observations to constrain the single degenerate scenario for Type Ia supernova progenitors. Our simulations show that the hole will remain open during centuries, although its partial or total closure at later times due to hydrodynamic instabilities is not excluded. Close to the edge of the hole, the Rayleigh-Taylor instability grows faster, leading to plumes that approach the edge of the for...

García-Senz, Domingo; Serichol, Nuria

2011-01-01

217

$10^{51}$ Ergs The Evolution of Shell Supernova Remnants  

CERN Multimedia

This paper reports on a workshop hosted by the University of Minnesota, March 23-26, 1997. It addressed fundamental dynamical issues associated with the evolution of shell supernova remnants and the relationships between supernova remnants and their environments. The workshop considered, in addition to classical shell SNRs, dynamical issues involving X-ray filled composite remnants and pulsar driven shells, such as that in the Crab Nebula. Approximately 75 participants with wide ranging interests attended the workshop. An even larger community helped through extensive on-line debates prior to the meeting. Each of the several sessions, organized mostly around chronological labels, also addressed some underlying, general physical themes: How are SNR dynamics and structures modified by the character of the CSM and the ISM and vice versa? How are magnetic fields generated in SNRs and how do magnetic fields influence SNRs? Where and how are cosmic-rays (electrons and ions) produced in SNRs and how does their prese...

Jones, T W; Jun, B I; Borkowski, K J; Dubner, G M; Frail, D A; Kang, H; Kassim, N E; McCray, R; Rudnick, Lawrence; Jun, Byung-Il; Borkowski, Kazimierz J.; Dubner, Gloria; Frail, Dale A.; Kang, Hyesung; Kassim, Namir E.; Cray, Richard Mc

1997-01-01

218

No cold dust within the supernova remnant Cassiopeia A  

CERN Document Server

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 (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; Rieke, G H; Lemke, D; Klaas, U; Hines, D C; Gordon, K D

2004-01-01

219

Supernova Remnants Interacting with Molecular Clouds: X-ray and Gamma-ray Signatures  

CERN Document Server

The giant molecular clouds (MCs) found in the Milky Way and similar galaxies play a crucial role in the evolution of these systems. The supernova explosions that mark the death of massive stars in these regions often lead to interactions between the supernova remnants (SNRs) and the clouds. These interactions have a profound effect on our understanding of SNRs. Shocks in SNRs should be capable of accelerating particles to cosmic ray (CR) energies with efficiencies high enough to power Galactic CRs. X-ray and gamma-ray studies have established the presence of relativistic electrons and protons is some SNRs and provided strong evidence for diffusive shock acceleration as the primary acceleration mechanism, including strongly amplified magnetic fields, temperature and ionization effects on the shock-heated plasmas, and modifications to the dynamical evolution of some systems. Because protons dominate the overall energetics of the CRs, it is crucial to understand this hadronic component even though electrons are ...

Slane, P; Ellison, D C; Dubner, G; Castro, D

2014-01-01

220

An Integral View of Fast Shocks around Supernova 1006  

CERN Document Server

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 km/s 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\\alpha\\ 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.

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

2013-01-01

 
 
 
 
221

Supernova Ejecta in the Youngest Galactic Supernova Remnant G1.9+0.3  

CERN Document Server

G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of about 1900, and most likely located near the Galactic Center. Only the outermost ejecta layers with free-expansion velocities larger than about 18,000 km/s have been shocked so far in this dynamically young, likely Type Ia SNR. A long (980 ks) Chandra observation in 2011 allowed spatially-resolved spectroscopy of heavy-element ejecta. We denoised Chandra data with the spatio-spectral method of Krishnamurthy et al., and used a wavelet-based technique to spatially localize thermal emission produced by intermediate-mass elements (IMEs: Si and S) and iron. The spatial distribution of both IMEs and Fe is extremely asymmetric, with the strongest ejecta emission in the northern rim. Fe Kalpha emission is particularly prominent there, and fits with thermal models indicate strongly oversolar Fe abundances. In a localized, outlying region in the northern rim, IMEs are less abundant than Fe, indicating tha...

Borkowski, K J; Hwang, U; Green, D A; Petre, R; Krishnamurthy, K; Willett, R

2013-01-01

222

A multi-wavelength study of Supernova Remnants in six nearby galaxies. II. New optically selected Supernova Remnants  

CERN Document Server

We present results from a study of optically emitting Supernova Remnants (SNRs) in six nearby galaxies (NGC 2403, NGC 3077, NGC 4214, NGC 4395, NGC 4449 and NGC 5204) based on deep narrow band H{\\alpha} and [SII] images as well as spectroscopic observations. The SNR classification was based on the detected sources that fulfill the well-established emission line flux criterion of [SII]/H{\\alpha} > 0.4. This study revealed ~400 photometric SNRs down to a limiting H{\\alpha} flux of 10^(-15) erg sec^(-1) cm^(-2). Spectroscopic observations confirmed the shock-excited nature of 56 out of the 96 sources with ([SII]/H{\\alpha})$_{phot}$> 0.3 (our limit for an SNR classification) for which we obtained spectra. 11 more sources were spectroscopically identified as SNRs although their photometric [SII]/H{\\alpha} ratio was below 0.3. We discuss the properties of the optically-detected SNRs in our sample for different types of galaxies and hence different environments, in order to address their connection with the surround...

Leonidaki, I; Zezas, A

2012-01-01

223

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

CERN Document Server

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

224

Expanding shells in the filamentary edge of the young supernova remnant RCW 103  

International Nuclear Information System (INIS)

Long-slit, echelle spectrograms have been obtained of the H ? and (N II) lines over the young supernova remnant RCW 103. One notable velocity feature is a narrow velocity spike (approx. 20km s"-"1 wide) with Vsub(HEL) approx. - 44km s"-"1 which is near the mean for the whole nebula. The overall velocity curves fail to match those expected from a remnant expanding radially at 1100-3000km s"-"1 as suggested by previous observations. Along the filamentary edge of the SNR several regions of #lt#0.4pc diameter are found which are expanding with velocities of up to 300km s"-"1; these are explained in terms of a model involving bow shocks formed when the supernova blast-wave overruns pre-existing condensations. (author)

1986-10-01

225

First optical detection from the supernova remnant G 15.1-1.6  

CERN Document Server

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

226

Remnant of the monoceros loop supernova at decametric waves  

International Nuclear Information System (INIS)

Observations of the flare of Monoceros Loop Supernova Remnant with the KTP-2 radiotelescope at frequencies of 14.7, 20, and 25 MHz with the 28' x 54' resolution for 25 MHz are presented. Detected is a sharp emission spectrum slope - the source flux does not exceed 100 Yy. The spectrum slope is caused by the source radiation absorption in ionized hydrogen as well as by the absorption of the background non-thermal radiation generated in the sight beam behind the remnant. Decrease in the background intensity in the remnant direction compensates the remnant flux and thus essentially amplifies the visible spectrum slope. Parameters of the ionized hydrogen region are electron temperature 4000 K, emission ratio 150 parsec x cmsup(-6)

1982-01-01

227

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

228

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

229

Neutral hydrogen associated with supernova remnants. I. The Cygnus loop  

International Nuclear Information System (INIS)

Observation of H I near the Cygnus Loop show that (1) the remnant is encountering interstellar clouds with densities 5--10 cm/sup -3/ adjacent to its optical filaments, and (2) the remnant does not contain the cool H I shell as predicted by current evolution theories which equate the present shock velocity with the optical expansion velocity. It is suggested that the remnant is adiabatically expanding into a two-phase medium, and the original energy of the explosion was 1051 ergs

1975-03-01

230

G306.3-0.9: A NEWLY DISCOVERED YOUNG GALACTIC SUPERNOVA REMNANT  

Energy Technology Data Exchange (ETDEWEB)

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 imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of {approx}160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24 {mu}m, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

Reynolds, Mark T.; Miller, Jon M.; Maitra, Dipankar; Gueltekin, Kayhan; Reis, Rubens C. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Loi, Shyeh T.; Murphy, Tara; Moss, Vanessa; Reeves, Sarah; Robbins, William J.; Gaensler, B. M. [Sydney Institute for Astronomy (SIfA), School of Physics, The University of Sydney, NSW 2006 (Australia); Gehrels, Neil; Petre, Robert [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kennea, Jamie A.; Siegel, Michael H.; Gelbord, Jonathan [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Kuin, Paul, E-mail: markrey@umich.edu [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom)

2013-04-01

231

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

CERN Document Server

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

232

Infrared Echoes near the Supernova Remnant Cassiopeia A  

CERN Document Server

Two images of Cassiopeia A obtained at 24 micrometer with the Spitzer Space Telescope over a one year time interval show moving structures outside the shell of the supernova remnant to a distance of more than 20 arcmin. Individual features exhibit apparent motions of 10 to 20 arcsec 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; Birkmann, S M; Le Floc'h, E; Gordon, K D; Egami, E; Bieging, J H; Hughes, J P; Young, E T; Hinz, J L; Quanz, S P; Hines, D C

2005-01-01

233

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

234

A Compact Central Object in the Supernova Remnant Kes 79  

CERN Document Server

A Chandra X-ray observation has detected an unresolved source at the center of the supernova remnant Kes 79. The best single-model fit to the source spectrum is a blackbody with an X-ray luminosity Lx (0.3-8.0 keV) = 7 x 10^{33} ergs s^{-1}. There is no evidence for a surrounding pulsar wind nebula. There are no cataloged counterparts at other wavelengths, but the absorption is high. The source properties are similar to the central source in Cas A even though the Kes 79 remnant is considerably older.

Seward, F D; Smith, R K; Sun, M

2003-01-01

235

Herschel Constraints on the Mass of Shocked Dust in the O-rich Supernova Remnant G292.0+1.8  

Science.gov (United States)

We present PACS and SPIRE images of the Galactic SNR G292.0+1.8, acquired during the Cycle 2 GO program of the Herschel Space Telescope. The goal of these images was to search for newly formed ejecta dust in this O-rich SNR, as well as study dust heating and destruction on small scales behind shock. Dust emission from radiatively shocked O-rich ejecta is clearly detected in the PACS blue band image (60-85 microns) enabled in large part by the excellent sensitivity and spatial resolution of PACS at those wavelengths. This is firm evidence of cold, freshly synthesized dust in the ejecta of G292.0+1.8. The outer blast wave shock is also detected in the PACS blue band, as well as the belt of circumstellar material associated with shocked circumstellar wind from the stellar progenitor. We have placed upper limits on emission at longer wavelengths in the red-band PACS images (130-210 microns), as well as SPIRE images between 250 microns and 500 microns. Using flux limits from both the PACS and longer wavelength SPIRE images, as well as existing IRS mapping spectra of G292, we create a broad-band spectrum of the SNR in the 14-500 micron range, placing global constraints on the mass and temperature of shocked circumstellar and ejecta dust in G292.0+1.8.

Ghavamian, Parviz; Williams, B. J.

2014-01-01

236

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

Science.gov (United States)

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?, [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? emission peaks of about 0.5? and discuss possible scenarios that could give rise to such high values. The kinematics of the remnant is analyzed by matching individual kinematic features in the echelle spectra obtained at the Cerro Tololo Inter-American Observatory with the morphological features revealed in the WFPC2 images. We detect a narrow H? emission component and identify it as diffuse preshock 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-1. The dense clouds are shocked up to line-of-sight velocities of 250 km s-1, and the less dense gas up to 300 km s-1. A few cloudlets have even higher radial velocities, reaching up to 350 km s-1. We confirm the presence of the cavity in the remnant and identify the center of explosion. Using archival Chandra and XMM-Newton data, we observe the same trends in surface brightness distribution for the optical and X-ray images. We carry out a spectral analysis of three regions that represent the most significant optical features.

Bilikova, J.; Williams, R. N. M.; Chu, Y.-H.; Gruendl, R. A.; Lundgren, B. F.

2007-12-01

237

Kinematic detection of supernova remnants in giant H II regions  

International Nuclear Information System (INIS)

In a kinematic survey of giant H II regions in M 101, four sources that have large velocity widths at low intensity levels are detected. Two of these large-velocity-width sources (LVWSs) are, within the limit of resolution, coincident with nonthermal radio sources several times as luminous as Cas A. The LVWS in NGC 5471 B is so bright that it is possible to separate its broad profile from the narrower profile of the background H II region. H-alpha CCD photometry, optical spectroscopy, and high-resolution radio data are combined to derive its physical properties, which support Skillman's (1985) identification of the object as a supernova remnant. The other LVWSs might be supernova remnants embedded in giant H II regions, unusually massive wind-driven shells, or the combination of both. 52 references

1986-01-01

238

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

CERN Document Server

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 $\\mu$m emission seen by {\\sl 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 $\\sim 100^\\circ$. We interpret this as evidence for a disk distribution of CSM before the SN, with the line of sight to the observer roughly in the disk plane. We present 2-D 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 AGB star companion.

Burkey, Mary T; Borkowski, Kazimierz J; Blondin, John M

2012-01-01

239

Observations of X-rays and Thermal Dust Emission from the Supernova Remnant Kes 75  

CERN Document Server

We present Spitzer Space Telescope and Chandra X-ray Observatory observations of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the detected flux at 24 microns and hot gas parameters from fitting spectra from new, deep X-ray observations to constrain models of dust emission, obtaining a dust-to-gas mass ratio M_dust/M_gas ~0.001. We find that a two-component thermal model, nominally representing shocked swept-up interstellar or circumstellar material and reverse-shocked ejecta, adequately fits the X-ray spectrum, albeit with somewhat high implied densities for both components. We surmise that this model implies a Wolf-Rayet progenitor for the remnant. We also present infrared flux upper limits for the central pulsar wind nebula.

Morton, T D; Borkowski, K J; Reynolds, S P; Helfand, D J; Gaensler, B M; Hughes, J P

2007-01-01

240

The Imprint of Presupernova Winds on Supernova Remnant Evolution Towards More Realistic Models for Type Ia Supernova Remnants and their Spectra  

CERN Document Server

Supernova remnants are usually analysed in the light of hydrodynamical models of the interaction of supernova ejecta with either a constant density ambient medium or a circumstellar medium produced by a constant presupernova wind. However, the ejection of energetic wind during the presupernova phase changes the ambient medium structure and, consequently, the early supernova remnant evolution. We have analysed the evolution of young remnants of type Ia supernovae, focusing on the imprint of the presupernova wind history on the supernova remnant structure and on the influence of the explosion mechanism. We have found that the remnant evolution is most sensitive to the explosion mechanism at ages not larger than a few hundred years, while the presupernova history shows its influence at later epochs, before the Sedov phase sets in.

Badenes, C

2002-01-01

 
 
 
 
241

X-ray maps of the Vela supernova remnant  

Science.gov (United States)

X-ray maps of the Vela supernova remnant in two energy channels, 0.1-0.4 keV and 0.4-0.8 keV, are presented. The data were obtained in 1975 from a SAS 3 satellite observation. We describe the Wiener filter technique used to deconvolve the angular response of the instrument from the data. The X-ray structure is compared with the optical and radio features of the region.

Hearn, D. R.; Larsen, S. E.; Richardson, J. A.

1980-01-01

242

On the spherical-axial transition in supernova remnants  

CERN Document Server

A new law of motion for supernova remnant (SNR) which introduces the quantity of swept matter in the thin layer approximation is introduced. This new law of motion is tested on 10 years observations of SN1993J. The introduction of an exponential gradient in the surrounding medium allows to model an aspherical expansion. A weakly asymmetric SNR, SN1006, and a strongly asymmetric SNR, SN1987a, are modeled. In the case of SN1987a the three observed rings are simulated.

Zaninetti, L

2011-01-01

243

A Model Grid for the Spectral Analysis of X-ray Emission in Young Type Ia Supernova Remnants  

CERN Multimedia

We address a new set of models for the spectral analysis of the X-ray emission from young, ejecta-dominated Type Ia supernova remnants. These models are based on hydrodynamic simulations of the interaction between Type Ia supernova explosion models and the surrounding ambient medium, coupled to self-consistent ionization and electron heating calculations in the shocked supernova ejecta, and the generation of synthetic spectra with an appropriate spectral code. The details are provided elsewhere, but in this paper we concentrate on a specific class of Type Ia explosion models (delayed detonations), commenting on the differences that arise between their synthetic X-ray spectra under a variety of conditions.

Badenes, C; Borkowski, K

2005-01-01

244

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

CERN Multimedia

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

245

Secondary Accceleration of Cosmic Rays by Supernova Shocks  

CERN Document Server

In the common model supernova shock-acceleration of cosmic rays there are two open questions: 1. where does the high energy cosmic rays below the knee (10$^4-10^6$ Gev) come from, and 2. are cosmic ray accelerated only at their origin or contineuosly during their residence in the Galaxy. We show that $10^15$ eV light nuclei are probably accelerted by associations of supernovae. The ratio of the spectra of secondary to primary cosmic rays would be affected by repeated acceleration (also called reacceleration or secondary acceleration) in the ISM during their propagation in the galaxy. The observed secondary and primary CR spectra are used to constrain the amount of such reacceleration by supernova remnants (SNR). Two cases are considered: weak shocks ($13$) of relatively young remnants. It is shown that weak shocks produce more reacceleration than what is permitted in the framework of the standard leaky box (SLB) model, making it inconsistent with dispersed acceleration that should be produced by SNR. If the S...

Wandel, A

1997-01-01

246

Correlation of Supernova Remnant Masers and Gamma-Ray Sources  

CERN Document Server

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

247

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

CERN Multimedia

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

248

CHANDRA ACIS Spectroscopy of N157B -- A Young Composite Supernova Remnant in a Superbubble  

CERN Multimedia

We present Chandra ACIS observations of N157B, a young supernova remnant located in the 30 Doradus star-formation region of the LMC. This remnant contains the most energetic pulsar known (PSR J0537-6910), which is surrounded by a bright nonthermal nebula that likely represents a toroidal pulsar wind terminal shock observed edge-on. We confirm the non-thermal nature of the comet-shaped X-ray emission feature and show that the spectral steepening of this feature away from the pulsar is quantitatively consistent with synchrotron cooling of shocked pulsar wind particles flowing downstream at a bulk velocity close to the speed of light. Around the cometary nebula we unambiguously detect a thermal component, which accounts for about 1/3 of the total 0.5 - 10 keV flux from the remnant. This thermal component is distributed among various clumps of metal-enriched plasma embedded in the low surface brightness X-ray-emitting diffuse gas. The relative metal enrichment pattern suggests that the mass of the supernova proge...

Chen, Y; Gotthelf, E V; Jiang, B; Chu, Y H; Gruendl, R A; Chen, Yang; Gotthelf, Eric V.; Jiang, Bing; Chu, You-Hua; Gruendl, Robert

2006-01-01

249

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

250

Nonthermal radiation from supernova remnants in the adiabatic stage of evolution  

International Nuclear Information System (INIS)

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

251

Geneva University: Particle Acceleration in supernova remnants and its implications for the origin of galactic cosmic rays  

CERN Multimedia

GENEVA UNIVERSITY École de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92 Wednesday 28 March 2012 SEMINAIRE DE PHYSIQUE CORPUSCULAIRE 11h15 - Science III, Auditoire 1S081 Particle Acceleration in supernova remnants and its implications for the origin of galactic cosmic rays Prof. Pasquale BLASI INAF, Arcetri Observatory, Firenze The process of cosmic ray energization in supernova remnant shocks is described by the theory of non linear diffusive shock acceleration (NLDSA). Such theory is able to describe the acceleration itself, the dynamical reaction of accelerated particles on the shock, and the crucial phenomenon of the magnetic field amplification, the very key to generate high energy cosmic rays. I will illustrate the basic aspects of this theoretical framework, as well as its successes and problems. I will then discuss the observations, in X-rays an...

Université de Genève

2012-01-01

252

SUPERNOVA EJECTA IN THE YOUNGEST GALACTIC SUPERNOVA REMNANT G1.9+0.3  

International Nuclear Information System (INIS)

G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of ?1900, and most likely located near the Galactic center. Only the outermost ejecta layers with free-expansion velocities ?>18,000 km s–1 have been shocked so far in this dynamically young, likely Type Ia SNR. A long (980 ks) Chandra observation in 2011 allowed spatially resolved spectroscopy of heavy-element ejecta. We denoised Chandra data with the spatio-spectral method of Krishnamurthy et al., and used a wavelet-based technique to spatially localize thermal emission produced by intermediate-mass elements (IMEs; Si and S) and iron. The spatial distribution of both IMEs and Fe is extremely asymmetric, with the strongest ejecta emission in the northern rim. Fe K? emission is particularly prominent there, and fits with thermal models indicate strongly oversolar Fe abundances. In a localized, outlying region in the northern rim, IMEs are less abundant than Fe, indicating that undiluted Fe-group elements (including 56Ni) with velocities >18,000 km s–1 were ejected by this SN. However, in the inner west rim, we find Si- and S-rich ejecta without any traces of Fe, so high-velocity products of O-burning were also ejected. G1.9+0.3 appears similar to energetic Type Ia SNe such as SN 2010jn where iron-group elements at such high free-expansion velocities have been recently detected. The pronounced asymmetry in the ejecta distribution and abundance inhomogeneities are best explained by a strongly asymmetric SN explosion, similar to those produced in some recent three-dimensional delayed-detonation Type Ia models.

2013-07-01

253

SUPERNOVA EJECTA IN THE YOUNGEST GALACTIC SUPERNOVA REMNANT G1.9+0.3  

Energy Technology Data Exchange (ETDEWEB)

G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of {approx}1900, and most likely located near the Galactic center. Only the outermost ejecta layers with free-expansion velocities {approx}>18,000 km s{sup -1} have been shocked so far in this dynamically young, likely Type Ia SNR. A long (980 ks) Chandra observation in 2011 allowed spatially resolved spectroscopy of heavy-element ejecta. We denoised Chandra data with the spatio-spectral method of Krishnamurthy et al., and used a wavelet-based technique to spatially localize thermal emission produced by intermediate-mass elements (IMEs; Si and S) and iron. The spatial distribution of both IMEs and Fe is extremely asymmetric, with the strongest ejecta emission in the northern rim. Fe K{alpha} emission is particularly prominent there, and fits with thermal models indicate strongly oversolar Fe abundances. In a localized, outlying region in the northern rim, IMEs are less abundant than Fe, indicating that undiluted Fe-group elements (including {sup 56}Ni) with velocities >18,000 km s{sup -1} were ejected by this SN. However, in the inner west rim, we find Si- and S-rich ejecta without any traces of Fe, so high-velocity products of O-burning were also ejected. G1.9+0.3 appears similar to energetic Type Ia SNe such as SN 2010jn where iron-group elements at such high free-expansion velocities have been recently detected. The pronounced asymmetry in the ejecta distribution and abundance inhomogeneities are best explained by a strongly asymmetric SN explosion, similar to those produced in some recent three-dimensional delayed-detonation Type Ia models.

Borkowski, Kazimierz J.; Reynolds, Stephen P. [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States); Hwang, Una [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Green, David A. [Cavendish Laboratory, 19 J.J. Thomson Ave., Cambridge CB3 0HE (United Kingdom); Petre, Robert [NASA/GSFC, Code 660, Greenbelt, MD 20771 (United States); Krishnamurthy, Kalyani; Willett, Rebecca, E-mail: kborkow@unity.ncsu.edu [Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708 (United States)

2013-07-01

254

Molecular Environment of the Supernova Remnant IC 443: Discovery of the Molecular Shells Surrounding the Remnant  

CERN Multimedia

We have carried out 12CO, 13CO, and C18O observations toward the mixed morphology supernova remnant (SNR) IC 443. The observations cover a 1.5*1.5 deg^2 area and allow us to investigate the overall molecular environment of the remnant. Some northern and northeastern partial shell structure of CO gas is around the remnant. One of the partial shells, about 5' extending beyond the northeastern border of the remnant's bright radio shell, seems to just confine the faint radio halo. On the other hand, some faint CO clumps can be discerned along the eastern boundary of the faint remnant's radio halo. Connecting the eastern CO clumps, the northeastern partial shell structures, and the northern CO partial shell, we can see that a half molecular ring structure appears to surround the remnant. The LSR velocity of the half-ring structure is in the range of -5 km/s to -2 km/s, which is consistent with that of the -4 km/s molecular clouds. We suggest that the half-ring structure of the CO emission at V_LSR -4 km/s is assoc...

Su, Yang; Yang, Ji; Zhou, Ping; Chen, Yang

2014-01-01

255

Annihilation emission from young supernova remnants  

CERN Document Server

A promising source of the positrons that contribute through annihilation to the diffuse Galactic 511keV emission is the beta-decay of unstable nuclei like 56Ni and 44Ti synthesised by massive stars and supernovae. Although a large fraction of these positrons annihilate in the ejecta of SNe/SNRs, no point-source of annihilation radiation appears in the INTEGRAL/SPI map of the 511keV emission. We exploit the absence of detectable annihilation emission from young local SNe/SNRs to derive constraints on the transport of MeV positrons inside SN/SNR ejecta and their escape into the CSM/ISM, both aspects being crucial to the understanding of the observed Galactic 511keV emission. We simulated 511keV lightcurves resulting from the annihilation of the decay positrons of 56Ni and 44Ti in SNe/SNRs and their surroundings using a simple model. We computed specific 511keV lightcurves for Cas A, Tycho, Kepler, SN1006, G1.9+0.3 and SN1987A, and compared these to the upper-limits derived from INTEGRAL/SPI observations. The pr...

Martin, Pierrick; Jiraskova, Sarka; Jean, Pierre; Diehl, Roland

2010-01-01

256

Ionization and Velocity Structure in the Supernova Remnant E0102-72  

CERN Document Server

The High Energy Transmission Grating (HETG) Spectrometer aboard the Chandra X-Ray Observatory was used to observe E0102-72, a ~1000 year old, oxygen rich supernova in the Small Magellanic Cloud. The HETG disperses the image of the remnant into a spectrum of images in the light of individual X-ray emission lines. Doppler shifts in the strongest lines of oxygen and neon reveal bulk motions of up to 2000 km/sec with a complex morphology. Comparison of progressive ionization stages of magnesium, neon, oxygen and silicon provide new insights into the mechanism of the `reverse shock' that heats the stellar ejecta.

Flanagan, K A; Davis, D S; Dewey, D; Houck, J C; Markert, T H; Schattenburg, M L

2001-01-01

257

Chandra Observations of the Crab-like Supernova Remnant G21.5-0.9  

CERN Multimedia

Chandra observations of the Crab-like supernova remnant G21.5-0.9 reveal a compact central core and spectral variations indicative of synchrotron burn-off of higher energy electrons in the inner nebula. The central core is slightly extended, perhaps indicating the presence of an inner wind-shock nebula surrounding the pulsar. No pulsations are observed from the central region, yielding an upper limit of ~40% for the pulsed fraction. A faint outer shell may be the first evidence of the expanding ejecta and blast wave formed in the initial explosion, indicating a composite nature for G21.5-0.9.

Slane, P O; Schulz, N S; Seward, F D; Hughes, J P; Gaensler, B M; Slane, Patrick; Chen, Yang; Schulz, Norbert S.; Seward, Frederick; Hughes, John P.; Gaensler, Bryan M.

2000-01-01

258

Observations of X-rays and Thermal Dust Emission from the Supernova Remnant Kes 75  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present Spitzer Space Telescope and Chandra X-ray Observatory observations of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the detected flux at 24 microns and hot gas parameters from fitting spectra from new, deep X-ray observations to constrain models of dust emission, obtaining a dust-to-gas mass ratio M_dust/M_gas ~0.001. We find that a two-component thermal model, nominally representing shocked swept-up interstellar or circumstellar material and...

Morton, T. D.; Slane, P.; Borkowski, K. J.; Reynolds, S. P.; Helfand, D. J.; Gaensler, B. M.; Hughes, J. P.

2007-01-01

259

Three-dimensional Simulations of the Non-thermal Broadband Emission from Young Supernova Remnants Including Efficient Particle Acceleration  

Science.gov (United States)

Supernova remnants are believed to be major contributors to Galactic cosmic rays. In this paper, we explore how the non-thermal emission from young remnants can be used to probe the production of energetic particles at the shock (both protons and electrons). Our model couples hydrodynamic simulations of a supernova remnant with a kinetic treatment of particle acceleration. We include two important back-reaction loops upstream of the shock: energetic particles can (1) modify the flow structure and (2) amplify the magnetic field. As the latter process is not fully understood, we use different limit cases that encompass a wide range of possibilities. We follow the history of the shock dynamics and of the particle transport downstream of the shock, which allows us to compute the non-thermal emission from the remnant at any given age. We do this in three dimensions, in order to generate projected maps that can be compared with observations. We observe that completely different recipes for the magnetic field can lead to similar modifications of the shock structure, although to very different configurations of the field and particles. We show how this affects the emission patterns in different energy bands, from radio to X-rays and ?-rays. High magnetic fields (>100 ?G) directly impact the synchrotron emission from electrons, by restricting their emission to thin rims, and indirectly impact the inverse Compton emission from electrons and also the pion decay emission from protons, mostly by shifting their cut-off energies to respectively lower and higher energies.

Ferrand, Gilles; Decourchelle, Anne; Safi-Harb, Samar

2014-07-01

260

HIGH-ENERGY EMISSION FROM THE COMPOSITE SUPERNOVA REMNANT MSH 15-56  

Energy Technology Data Exchange (ETDEWEB)

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 SNR properties, including an age of 16,500 yr. Modeling of the {gamma}-ray emission detected by Fermi shows that the emission may originate from the reverse shock-crushed PWN.

Temim, Tea [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Slane, Patrick; Plucinsky, Paul P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Castro, Daniel [MIT-Kavli Center for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Gelfand, Joseph [New York University Abu Dhabi (United Arab Emirates); Dickel, John R., E-mail: tea.temim@nasa.gov [Physics and Astronomy Department, University of New Mexico, MSC 07-4220, Alburquerque, NM 87131 (United States)

2013-05-01

 
 
 
 
261

Molecular Environment of the Supernova Remnant IC 443: Discovery of the Molecular Shells Surrounding the Remnant  

Science.gov (United States)

We have carried out 12CO, 13CO, and C18O observations toward the mixed morphology supernova remnant (SNR) IC 443. The observations cover a 1.°5 × 1.°5 area and allow us to investigate the overall molecular environment of the remnant. Some northern and northeastern partial shell structure of CO gas is around the remnant. One of the partial shells, about 5' extending beyond the northeastern border of the remnant's bright radio shell, seems to just confine the faint radio halo. On the other hand, some faint CO clumps can be discerned along the eastern boundary of the faint remnant's radio halo. Connecting the eastern CO clumps, the northeastern partial shell structures, and the northern CO partial shell, we can see that a half molecular ring structure appears to surround the remnant. The LSR velocity of the half-ring structure is in the range of -5 km s-1 to -2 km s-1, which is consistent with that of the -4 km s-1 molecular clouds. We suggest that the half-ring structure of the CO emission at V LSR ~ -4 km s-1 is associated with the SNR. The structures are possibly swept up by the stellar winds of SNR IC 443's massive progenitor. Based on the Wide-field Infrared Survey Explorer and the Two Micron All Sky Survey near-IR database, 62 young stellar object (YSO) candidates are selected within the radio halo of the remnant. These YSO candidates concentrated along the boundary of the remnant's bright radio shell are likely to be triggered by the stellar winds from the massive progenitor of SNR IC 443.

Su, Yang; Fang, Min; Yang, Ji; Zhou, Ping; Chen, Yang

2014-06-01

262

Very high resolution calculations of very young supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

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/sup -9/ g/cm/sup 3/) and the circumstellar medium (10/sup -24/ g/cm/sup 3/) 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.

Jones, E.M.; Smith, B.W.

1982-01-01

263

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/cm"3) and the circumstellar medium (10"-"2"4 g/cm"3) 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

264

Search for surviving companions in type Ia supernova remnants  

CERN Document Server

The nature of the progenitor systems of type~Ia supernovae is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions. Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- and helium-rich surviving companions, the color and magnitude of main-sequence- and helium-rich surviving companions are predicted as functions of time. The surviving companion candidates in Galactic type~Ia supernova remnants and nearby extragalactic type~Ia supernova remnants are discussed. We find that the maximum detectable distance of main-sequence surviving companions (helium-rich surviving companions) is $0.6-4$~Mpc ($0.4-16$~Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to s...

Pan, Kuo-Chuan; Taam, Ronald E

2014-01-01

265

No cold dust within the supernova remnant Cassiopeia A.  

Science.gov (United States)

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. PMID:15577902

Krause, Oliver; Birkmann, Stephan M; Rieke, George H; Lemke, Dietrich; Klaas, Ulrich; Hines, Dean C; Gordon, Karl D

2004-12-01

266

A New Young Galactic Supernova Remnant Containing a Compact Object: G15.9+0.2  

CERN Document Server

We identify the radio-emitting shell-type supernova remnant G15.9+0.2 as a relatively young remnant containing an X-ray point source that may be its associated neutron star. The integrated spectrum of the remnant shell obtained from our 30 ks exploratory Chandra observation shows very strong lines that require elevated element abundances from ejecta, in particular of sulfur. A plane-shock model fit gives a temperature $kT = 0.9 (0.8, 1.0)$ keV, an ionization timescale $n_et = 6 (4, 9) \\times 10^{10}$ cm$^{-3}$ s, and a sulfur abundance of 2.1 (1.7, 2.7) times solar (90% confidence limits). Two-component models with one solar and one enriched component are also plausible, but are not well constrained by the data. Various estimates give a remnant age of order $10^3$ yr, which would make G15.9+0.2 among the dozen or so youngest remnants in the Galaxy. The sparse point source spectrum is consistent with either a steep $\\Gamma \\sim$ 4 power law or a $kT \\sim$ 0.4 keV blackbody. The spectrum is absorbed by a H colu...

Reynolds, S P; Hwang, U; Harrus, I; Petre, R; Dubner, G

2006-01-01

267

Multi-wavelength analysis of supernova remnant MSH11-61A  

Science.gov (United States)

Due to its centrally bright X-ray morphology and limb brightened radio profile, supernova remnant (SNR) MSH11-61A (G290.1-0.8) is classified as mixed morphology. The evolutionary sequence which leads to this centrally bright X-ray morphology is not well understood and currently different models can only explain some of the features seen in individual cases. In this analysis we present a study of MSH11-61A using archival Suzaku data. Our preliminary results indicate enhanced abundances, as previously suggested by ASCA observations and we derive the associated age, energy and ambient density of the remnant using models that we constructed in an attempt to reproduce the observed X-ray properties. Additionally, MSH11-61A is thought to be interacting with a molecular cloud towards the west/south west of the remnant. As observations of thermal and non-thermal emission of SNRs have provided increasing support in favour of cosmic rays being accelerated at the shock front of the remnant, SNRs known to be interacting with molecular clouds provide an effective target for detecting and studying gamma-rays. Using 64 months of Fermi-LAT gamma-ray data, we perform a spatial and spectral analysis of the gamma-ray emission in the region of this remnant, allowing us to constrain the origin of the detected emission.

Auchettl, Katie; Slane, Patrick O.; Castro, Daniel

2014-06-01

268

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

269

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

Energy Technology Data Exchange (ETDEWEB)

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{sub Sun }, 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 {alpha}-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.

Hwang, Una [Goddard Space Flight Center, Greenbelt, MD (United States); Laming, J. Martin, E-mail: Una.Hwang-1@gsfc.nasa.gov, E-mail: laming@nrl.navy.mil [Naval Research Laboratory, Code 7674L, Washington, DC 20375 (United States)

2012-02-20

270

A Chandra X-ray Survey of Ejecta in the Cassiopeia A Supernova Remnant  

CERN Multimedia

We present a survey of the X-ray emitting ejecta in the Cassiopeia A supernova remnant 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_sun, which accounts for nearly all of the mass expected in Fe ejecta. We find two populations of Fe ejecta, that associated with norma...

Hwang, Una

2011-01-01

271

Aspherical Supernova Shock Breakout and the Observations of Supernova 2008D  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Couch, Sean M.; Pooley, David; Wheeler, J. Craig; Milosavljevic, Milos

2010-01-01

272

The population of supernova remnants in the Magellanic Clouds  

CERN Document Server

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

273

Soft x-ray spectroscopy of the Vela supernova remnant  

Science.gov (United States)

The CODEX sounding rocket payload was designed and flown to significantly improve spectral resolution of the Vela supernova remnant (SNR) in the soft x-ray (0.1--1.0 keV) bandpass. High spectral resolution (E/Delta E > 40) across its 3.25° x 3.25° field of view would disentangle thermal emission from nonthermal or line emission components to constrain the age when SNRs stop emitting nonthermal x-rays. Relatively recent observations have found significant nonthermal emission from remnants up to several kyr old, but CODEX encountered concurrent problems of higher noise and lower signal than expected, leaving the thermal versus nonthermal question unanswered in the 11 kyr-old Vela SNR. This thesis covers the motivation, design, and post-flight analysis of the CODEX instrument and data from its flight.

Zeiger, Benjamin R.

274

Hydrodynamic modelling of ejecta shrapnel in the Vela supernova remnant  

CERN Multimedia

Many supernova remnants (SNRs) are characterized by a knotty ejecta structure. The Vela SNR is an excellent example of remnant in which detached clumps of ejecta are visible as X-ray emitting bullets that have been observed and studied in great detail. We aim at modelling the evolution of ejecta shrapnel in the Vela SNR, investigating the role of their initial parameters (position and density) and addressing the effects of thermal conduction and radiative losses. We performed a set of 2-D hydrodynamic simulations describing the evolution of a density inhomogeneity in the ejecta profile. We explored different initial setups. We found that the final position of the shrapnel is very sensitive to its initial position within the ejecta, while the dependence on the initial density contrast is weaker. Our model also shows that moderately overdense knots can reproduce the detached features observed in the Vela SNR. Efficient thermal conduction produces detectable effects by determining an efficient mixing of the ejec...

Miceli, M; Reale, F; Bocchino, F; Peres, G

2013-01-01

275

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.

2011-08-10

276

Supernova Remnants and Nucleosynthesis (fos 30): CYCLE4-AUG-CARRYOVER  

Science.gov (United States)

Overall program: UV and optical spectra of four supernova remnants (SNRs) will be used to study a number of problems related to abundances, grain destruction, interstellar medium properties and physical conditions in SNR shocks. Representatives of three of the main classes of SNRs (Crab-nebula like, Balmer-line and "normal") will be studied in the LMC, where reasonably low reddening permits UV observations. In earlier parts of the program, an oxygen-rich SNR in NGC 4449 was observed, taking advantage of the small FOS slits to isolate the SNR from surrounding H II emission. Two M33 SNRs that were previously part of this proposal have been dropped due to time limitations. This program: FOS UV/optical spectra of two LMC remnants are to be obtained, following up on EARLY ACQ images from cycle 2. This program has been carried over from before the servicing mission in December 1993.

Davidsen, Arthur

1994-07-01

277

The Nature of the Compact Supernova Remnants in Starburst Galaxies  

CERN Document Server

Radio observations of starburst regions in galaxies have revealed groups of compact nonthermal sources that may be radiative supernova remnants expanding in the interclump medium of molecular clouds. Because of the high pressure in starburst regions, the interclump medium may have a density ~ 10^3 H atoms cm^{-3} in a starburst nucleus like M82 and ~ 10^4 H atoms cm^{-3} in an ultraluminous galaxy like Arp 220. In M82, our model can account for the sizes, the slow evolution, the high radio luminosities, and the low X-ray luminosities of the sources. We predict expansion velocities ~ 500 km/s, which is slower than the one case measured by VLBI techniques. Although we predict the remnants to be radiative, the expected radiation is difficult to detect because it is at infrared wavelengths and the starburst is itself very luminous; one detection possibility is broad [OI] 63 micron line emission at the positions of the radio remnants. The more luminous and compact remnants in Arp 220 can be accounted for by the hi...

Chevalier, R A; Chevalier, Roger A.; Fransson, Claes

2001-01-01

278

A search for supernova remnants in the vicinity of pulsars  

International Nuclear Information System (INIS)

An area of approximately on square degree was studied around the six pulsars PSR 0329 + 54, PSR 0525 + 21, PSR 0809 + 74, PSR 0823 + 26, PSR 0904 + 77 and PSR 0950 + 08 with the Westerbork Synthesis Radio Telescope (WSRT) at lambda 21 cm to search for extended regions of radio emission. To the limit of sensitivity of the WSRT, we find in no case a significant candidate for a supernova remnant or a pulsar 'ghost'. In four of the six cases the pulsar is detected. Additionally, the unrelated radio sources in the field are described. The sensitivity of the WSRT to extended sources is discussed. (orig.)

1974-10-01

279

Radio and X-ray emission from supernova remnants  

International Nuclear Information System (INIS)

In this paper it was studied the statistical correlation between radio and X-ray emissions from shell-type supernova remnants (SNR). The primary aim of this work is to test the model of radio emission of shell-type SNRs presented by one of the authors. Based on this model of radio emission, by using the Monte Carlo techniques it was simulated statistical relations radio-X-ray luminosities which then were compared with the observations. X-ray emission is assumed to be thermal. To have a uniform statistical material it was used observational data on the SNRs in Magellanic Clouds

2010-06-01

280

Dust Lifetimes and Grain Destruction Rates by Supernova Remnants in the Magellanic Clouds  

Science.gov (United States)

The presence of dust in galaxies has a profound effect on their spectral appearance and on the many processes that determine the physical, chemical, and thermal state of their interstellar medium (ISM). Despite the many different manifestation of interstellar dust in the Milky Way and external galaxies, its nature, origin, and evolution are still poorly understood. The understanding of the dust destruction rates by supernova shocks in particular is extremely important for understanding its origin. The amount of grain destruction determines whether the dust budget can be balanced by dust formation in stellar sources, or whether dust growth in molecular clouds is required. Due to their extensive wavelength coverage and known distance, the Magellanic Clouds offer a unique opportunity for studying dust destruction rates and lifetimes in the ISM. I will present new estimates of dust destruction rates by supernova remnants in the Magellanic Clouds and discuss their implications for dust evolution models.

Temim, Tea; Dwek, E.; Meixner, M.; Boyer, M. L.; Tchernyshyov, K.; Gall, C.

2014-01-01

 
 
 
 
281

Spherically symmetric relativistic MHD simulations of pulsar wind nebulae in supernova remnants  

CERN Multimedia

Pulsars, formed during supernova explosions, are known to be sources of relativistic magnetized winds whose interaction with the expanding supernova remnants (SNRs) gives rise to a pulsar wind nebula (PWN). We present spherically symmetric relativistic magnetohydrodynamics (RMHD) simulations of the interaction of a pulsar wind with the surrounding SNR, both in particle and magnetically dominated regimes. As shown by previous simulations, the evolution can be divided in three phases: free expansion, a transient phase characterized by the compression and reverberation of the reverse shock, and a final Sedov expansion. The evolution of the contact discontinuity between the PWN and the SNR (and consequently of the SNR itself) is almost independent of the magnetization of the nebula as long as the total (magnetic plus particle) energy is the same. However, a different behaviour of the PWN internal structure is observable during the compression-reverberation phase, depending on the degree of magnetization=2E The si...

Bucciantini, N; Zanna, L D; Amato, E

2003-01-01

282

New Models for X-Ray Synchrotron Radiation from the Remnant of Supernova 1006 AD  

CERN Document Server

Galactic cosmic rays up to energies of around 10^15 eV are assumed to originate in supernova remnants (SNRs). The shock wave of a young SNR like SN 1006 AD can accelerate electrons to energies greater than 1 TeV, where they can produce synchrotron radiation in the X-ray band. A new model (SRESC) designed to model synchrotron X-rays from Type Ia supernovae can constrain values for the magnetic-field strength and electron scattering properties, with implications for the acceleration of the unseen ions which dominate the cosmic-ray energetics. New observations by ASCA, ROSAT, and RXTE have provided enormously improved data, which now extend to higher X-ray energies. These data allow much firmer constraints. We will describe model fits to these new data on SN 1006 AD, emphasizing the physical constraints that can be placed on SNRs and on the cosmic-ray acceleration process.

Dyer, K K; Borkowski, K J

2000-01-01

283

3D simulations of the non-thermal broad-band emission from young supernova remnants including efficient particle acceleration  

CERN Document Server

Supernova remnants are believed to be the major contributors to Galactic cosmic rays. In this paper, we explore how the non-thermal emission from young remnants can be used to probe the production of energetic particles at the shock (both protons and electrons). Our model couples hydrodynamic simulations of a supernova remnant with a kinetic treatment of particle acceleration. We include two important back-reaction loops upstream of the shock: energetic particles can (i) modify the flow structure and (ii) amplify the magnetic field. As the latter process is not fully understood, we use different limit cases that encompass a wide range of possibilities. We follow the history of the shock dynamics and of the particle transport downstream of the shock, which allows us to compute the non-thermal emission from the remnant at any given age. We do this in 3D, in order to generate projected maps that can be compared with observations. We observe that completely different recipes for the magnetic field can lead to sim...

Ferrand, Gilles; Safi-Harb, Samar

2014-01-01

284

High-velocity iron absorption lines in supernova remnant 1006  

International Nuclear Information System (INIS)

The International Ultraviolet Explorer spectrum of the Schweizer-Middleeditch star projected near the center of supernova remnant SNR 1006 shows an sdOB Star continuum, with very strong, broad absorption lines. Strong Fe"+ resonance absorption lines are present. Their centers show zero radial velocity, while their profiles are broadened by approx.5-6 x 10_3 km s"-_1. Redshifted Si/sup +,+2,+3/ lines at #betta#/sub r/approx.5 x 10_3 km s"-_1 have also been tentatively identified. We argue that the absorptions must occur in the ejecta of the supernova. The strength and symmetric width of the Fe"+ lines suggests that the bulk of ejecta is iron, in agreement with the current theory for the origin of Type I supernovae. The previous failure to detect strong Fe emission lines in the X-ray spectrum of this and other young Type I SNRs suggests that the ejecta may not have had time to interact significantly with the ambient medium. The presence of redshifted absorption lines due to supernova ejecta in its spectrum indicates that this star is located behind the SNR and is not physically associated with it

1983-06-01

285

The properties of the progenitor, neutron star, and pulsar wind in the supernova remnant Kes 75  

Science.gov (United States)

By studying composite supernova remnants (SNRs), remnants which contain a pulsar wind nebula (PWN), it is possible to estimate physical properties of the progenitor explosion, central neutron star, and its pulsar wind that are difficult to measure directly. This is best done by fitting the dynamical and broadband spectral properties of a PWN with an evolutionary model for a PWN inside an SNR. We apply such a model to the composite SNR Kes 75, whose associated pulsar PSR J1846-0258 is thought to have an extremely strong surface magnetic field. If ˜ 3 M_? of mass was ejected in the supernova, our model suggests a normal or slightly subenergetic supernova in a low density environment. Additionally, for the measured pre-outburst braking index of p=2.65, our model prefers an age of {˜ 430} years and an initial spin period P_0 ˜ 0.2 s. Lastly, the magnetization of the pulsar wind and energy spectrum of particles injected at the termination shock are similar to those observed from other PWNe powered by less magnetized neutron stars. While further study is needed to verify these results, they are nominally inconsistent with strong neutron star magnetic fields resulting from very fast initial rotation.

Gelfand, J. D.; Slane, P. O.; Temim, T.

2014-03-01

286

X-RAY EMISSION FROM STRONGLY ASYMMETRIC CIRCUMSTELLAR MATERIAL IN THE REMNANT OF KEPLER'S SUPERNOVA  

Energy Technology Data Exchange (ETDEWEB)

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 {mu}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 {approx}100 Degree-Sign . 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., E-mail: reynolds@ncsu.edu [Department of Physics, North Carolina State University, Raleigh NC 27695-8202 (United States)

2013-02-10

287

Spitzer observations of the N157B supernova remnant and its surroundings  

CERN Document Server

(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

288

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

289

Nonthermal and thermal emission from the supernova remnant RX J1713.7-3946  

CERN Multimedia

A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) is employed to investigate the properties of SNR RX J1713.7-3946. Observations of the non-thermal radio and X-ray emission spectra as well as the H.E.S.S. measurements of the very high energy gamma-ray emission are used to constrain the astronomical and CR acceleration parameters of the system. It is argued that RX J1713.7-3946 is a core collapse supernova (SN) of type II/Ib with a massive progenitor, has an age of ~1600 yr and is at a distance of ~1 kpc. It is in addition assumed that the CR injection/acceleration takes place uniformly across the shock surface for this kind of core collapse SNR. The theory gives a consistent description for all the existing observational data, including the non-detection of thermal X-rays and the spatial correlation of the X-ray and gamma-ray emission in the remnant. Specifically it is shown that an efficient production of nuclear CRs, leading to strong shock modification and a large down...

Berezhko, E G

2009-01-01

290

A molecular shell with star formation toward the supernova remnant G349.7+0.2  

CERN Document Server

A field of ~38"x38" around the supernova remnant (SNR) G349.7+0.2 has been surveyed in the CO J=1-0 transition with the 12 Meter Telescope of the NRAO, using the On-The-Fly technique. The resolution of the observations is 54". We have found that this remnant is interacting with a small CO cloud which, in turn, is part of a much larger molecular complex, which we call the ``Large CO Shell''. The Large CO Shell has a diameter of about 100 pc, an H_2 mass of 930,000 solar masses, and a density of 35 cm-3. We investigate the origin of this structure and suggest that an old supernova explosion ocurred about 4 million years ago, as a suitable hypothesis. Analyzing the interaction between G349.7+0.2 and the Large CO Shell, it is possible to determine that the shock front currently driven into the molecular gas is a non-dissociative shock (C-type), in agreement with the presence of OH 1720 MHz masers. The positional and kinematical coincidence among one of the CO clouds that constitute the Large CO Shell, an IRAS poi...

Reynoso, E M; Reynoso, Estela M; Mangum, Jeffrey G.

2001-01-01

291

Effect of stellar structure on supernova remnant evolution  

Energy Technology Data Exchange (ETDEWEB)

One-dimensional hydrodynamic calculations have been done of 1E51 erg explosions in 15M/sub sun/ stars. A steep external density gradient to the pre-supernova model of Weaver et al was appended with the results: (1) the outer shock wave decelerates throughout the pre-Sedov phase, (2) the expanding stellar envelope and the shocked interstellar material are Rayleigh-Taylor stable until the Sedov phase, and (3) steep internal density gradients are R-T unstable during the early expansion and may be the source of high velocity knots seen in Cas A.

Jones, E.M.; Smith, B.W.; Straka, W.C.

1980-01-01

292

Spitzer Observations of the Type Ia Supernova Remnant N103B: Kepler's Older Cousin?  

CERN Document Server

We report results from Spitzer observations of SNR 0509-68.7, also known as N103B, a young Type Ia supernova remnant in the Large Magellanic Cloud that shows interaction with a dense medium in its western hemisphere. Our images show that N103B has strong IR emission from warm dust in the post-shock environment. The post-shock gas density we derive, 45 cm$^{-3}$, is much higher than in other Type Ia remnants in the LMC, though a lack of spatial resolution may bias measurements towards regions of higher than average density. This density is similar to that in Kepler's SNR, a Type Ia interacting with a circumstellar medium. Optical images show H$\\alpha$ emission along the entire periphery of the western portion of the shock, with [O III] and [S II] lines emitted from a few dense clumps of material where the shock has become radiative. The dust is silicate in nature, though standard silicate dust models fail to reproduce the "18 $\\mu$m" silicate feature that peaks instead at 17.3 $\\mu$m. We propose that the dense...

Williams, Brian J; Reynolds, Stephen P; Ghavamian, Parviz; Raymond, John C; Long, Knox S; Blair, William P; Winkler, P Frank; Sankrit, Ravi; Hendrick, Sean P

2014-01-01

293

Chandra Studies of Nonthermal Emission from Supernova Remnants and Pulsar Wind Nebulae  

CERN Multimedia

While supernova remnants (SNRs) have long been considered prime candidates as sources of cosmic rays, it is only recently that X-ray observations have identified several shell-type SNRs dominated by nonthermal emission, thus revealing shock-accelerated electrons with energies extending far beyond the typical thermal spectrum. Two of these SNRs have been detected as sources of VHE gamma-rays.In other remnants, discrepancies between the shock velocity and the electron temperature point to a strong cosmic ray component that has thrived at the expense of the thermal gas. Modeling of the radio, X-ray, and gamma-ray emission provides constraints on particle acceleration as well as the properties of the medium in which the mechanism prospers. Crab-like pulsar wind nebulae (PWNe) are characterized by a termination shock at which the wind is forced to join the slow expansion of the outer nebula. These shocks also act as sites in which particles are boosted to high energies; the X-ray emission from the Crab Nebula, as ...

Slane, P O

2002-01-01

294

Dust Formation Observed in Young Supernova Remnants with Spitzer  

CERN Document Server

We present dust features and masses observed in young supernova remnants (SNRs) with Spitzer IRS mapping and staring observations of four youngest supernova remnants: SNR 1E102.2-7219 (E0102) in the SMC, Cas A and G11.2-0.3 in our Galaxy, and N132D in the LMC. The spectral mapping data revealed a number of dust features which include 21 micron-peak dust and featureless dust in Cas A and 18-micron peak dust in E0102 and N132D. The 18 micron-peak feature is fitted by a mix of MgSiO$_3$ and solid Si dust grains, while the 21-micron peak dust is by a mix of silicates and FeO; we also explore dust fitting using Continuous Distribution of Ellipsoid grain models. We report detection of CO fundamental band from Cas A in near-infrared. We review dust features observed and identified in other SNRs. The dust emission is spatially correlated with the ejecta emission, showing dust is formed in SN ejecta. The spectra of E0102 show rich gas lines from ejecta including strong ejecta lines of Ne and O, including two [Ne III] ...

Rho, J; Tappe, A; Rudnick, L; Kozasa, T; Hwang, U; Andersen, M; Gomez, H; DeLaney, T; Dunne, L; Slavin, J

2009-01-01

295

Spitzer Observations of Dust Destruction in the Puppis A Supernova Remnant  

Science.gov (United States)

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 micrometers 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.

Arendt, Richard G.; Dweek, Eli; Blair, William P.; Ghavamian, Parviz; Hwang, Una; Long, Knox X.; Petre, Robert; Rho, Jeonghee; Winkler, P. Frank

2010-01-01

296

Detection of Far-Infrared Water Vapor, Hydroxyl, and Carbon Monoxide Emissions from the Supernova Remnant 3C 391  

CERN Document Server

We report the detection of shock-excited far-infrared emission of H2O, OH, and CO from the supernova remnant 3C 391, using the ISO Long-Wavelength Spectrometer. This is the first detection of thermal H2O and OH emission from a supernova remnant. For two other remnants, W~28 and W~44, CO emission was detected but OH was only detected in absorption. The observed H2O and OH emission lines arise from levels within ~400 K of the ground state, consistent with collisional excitation in warm, dense gas created after the passage of the shock front through the dense clumps in the pre-shock cloud. The post-shock gas we observe has a density ~2x10^5 cm^{-3} and temperature 100-1000 K, and the relative abundances of CO:OH:H2O in the emitting region are 100:1:7 for a temperature of 200 K. The presence of a significant column of warm H2O suggests that the chemistry has been significantly changed by the shock. The existence of significant column densities of both OH and H2O, which is at odds with models for non-dissociative ...

Reach, W T; Reach, William T.; Rho, Jeonghee

1998-01-01

297

A joint spectro-imaging analysis of the XMM-Newton and HESS observations of the supernova remnant RX J1713.7-3946  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The supernova remnant (SNR) RX J1713.7-3946 (also known as G347.3-0.5) is part of the class of remnants dominated by synchrotron emission in X-rays. It is also one of the few shell-type SNRs observed at TeV energies allowing to investigate particle acceleration at SNRs shock. Our goal is to compare spatial and spectral properties of the remnant in X- and gamma-rays to understand the nature of the TeV emission. This requires to study the remnant at the same spatial scale at...

Acero, F.; Ballet, J.; Decourchelle, A.; Lemoine-goumard, M.; Ortega, M.; Giacani, E.; Dubner, G.; Cassam-chenai, G.

2009-01-01

298

Spitzer IRS Observations of the XA Region in the Cygnus Loop Supernova Remnant  

Science.gov (United States)

We report on spectra of two positions in the XA region of the Cygnus Loop supernova remnant obtained with the InfraRed Spectrograph on the Spitzer Space Telescope. The spectra span the 10-35 ?m wavelength range, which contains a number of collisionally excited forbidden lines. These data are supplemented by optical spectra obtained at the Whipple Observatory and an archival UV spectrum from the International Ultraviolet Explorer. Coverage from the UV through the IR provides tests of shock wave models and tight constraints on model parameters. Only lines from high ionization species are detected in the spectrum of a filament on the edge of the remnant. The filament traces a 180 km s-1 shock that has just begun to cool, and the oxygen to neon abundance ratio lies in the normal range found for Galactic H II regions. Lines from both high and low ionization species are detected in the spectrum of the cusp of a shock-cloud interaction, which lies within the remnant boundary. The spectrum of the cusp region is matched by a shock of about 150 km s-1 that has cooled and begun to recombine. The post-shock region has a swept-up column density of about 1.3 × 1018 cm-2, and the gas has reached a temperature of 7000-8000 K. The spectrum of the Cusp indicates that roughly half of the refractory silicon and iron atoms have been liberated from the grains. Dust emission is not detected at either position. Based on observations made with the Spitzer Space Telescope.

Sankrit, Ravi; Raymond, John C.; Bautista, Manuel; Gaetz, Terrance J.; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Long, Knox S.

2014-05-01

299

HFPK 334: An unusual Supernova Remnant in the Small Magellanic Cloud  

CERN Multimedia

We present new Australia Telescope Compact Array (ATCA) radio-continuum and XMM-Newton/Chandra X-ray Observatory (CXO) observations of the unusual supernova remnant HFPK 334 in the Small Magellanic Cloud (SMC). The remnant follows a shell type morphology in the radio-continuum and has a size of $\\sim$20~pc at the SMC distance. The X-ray morphology is similar, however, we detect a prominent point source close to the center of the SNR exhibiting a spectrum with a best fit powerlaw with a photon index of $\\Gamma = 2.7 \\pm 0.5$. This central point source is most likely a background object and cannot be directly associated with the remnant. The high temperature, nonequilibrium conditions in the diffuse region suggest that this gas has been recently shocked and point toward a younger SNR with an age of $\\lesssim 1800$ years. With an average radio spectral index of $\\alpha=-0.59\\pm0.09$ we find that an equipartition magnetic field for the remnant is $\\sim$90~$\\mu$G, a value typical of younger SNRs in low-density env...

Crawford, E J; McEntaffer, R L; Brantseg, T; Heitritter, K; Roper, Q; Haberl, F; Urosevi?, D

2014-01-01

300

A Spatial and Spectral Study of Nonthermal Filaments in Historical Supernova Remnants: Observational Results with Chandra  

CERN Document Server

The outer shells of young supernova remnants (SNRs) are the most plausible acceleration sites of high-energy electrons with the diffusive shock acceleration (DSA) mechanism. We studied spatial and spectral properties close to the shock fronts in four historical SNRs (Cas A, Kepler's remnant, Tycho's remnant, and RCW 86) with excellent spatial resolution of {\\it Chandra}. In all of the SNRs, hard X-ray emissions were found on the rims of the SNRs, which concentrate in very narrow regions (so-called "filaments"); apparent scale widths on the upstream side are below or in the order of the point spread function of {\\it Chandra}, while 0.5--40 arcsec (0.01--0.4 pc) on the downstream side with most reliable distances. The spectra of these filaments can be fitted with both thermal and nonthermal (power-law and {\\tt SRCUT}) models. The former requires unrealistic high temperature ($\\ga$2 keV) and low abundances ($\\la$1 solar) for emission from young SNRs and may be thus unlikely. The latter reproduces the spectra wit...

Bamba, A; Yoshida, T; Terasawa, T; Koyama, K; Bamba, Aya; Yamazaki, Ryo; Yoshida, Tatsuo; Terasawa, Toshio; Koyama, Katsuji

2004-01-01

 
 
 
 
301

A Chandra X-Ray Survey of Ejecta in the Cassiopeia A Supernova Remnant  

Science.gov (United States)

We present a survey of the X-ray emitting ejecta in the Cassiopeia A supernova remnant 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 are highly peaked and suggest that the ejecta were subjected to multiple secondary shocks. 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 as well as showing the distribution of the mass of various elements over the remnant. The total shocked Fe mass appears to be roughly 0.14 Solar Mass, 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 associated with alpha-rich freeze-out, with a mass ratio of approximately 2:1. Surprisingly, essentially all of this Fe (both components) is well outside the central regions of the SNR, presumably having been ejected by hydrodynamic instabilities during the explosion. We discuss this, and its implications for the neutron star kick.

Hwang, Una; Laming, J. Martin

2011-01-01

302

Analytical methods for the hydrodynamical evolution of supernova remnants  

International Nuclear Information System (INIS)

We present haere an analytical method for computing the hydrodynamical structure and evolution of supernova remnants (SNRs). We show that simple approximations can be derived by using Lagrangian coordinates, rather than Eulerian; in particular, the pressure distribution is obtained as an almost linear function of the mass, M (r); this constitutes the first order of our approximation. The set of the three fundamental hydrodynamic equations, which are partial derivative equations, is reduced to an ordinary differential equation for a function of only one variable. A further simplification characteristic of this method is that the velocity field does not appear explicitly in our equations, and need not be computed. The results obtained in this manner are very accurate in cases of self-similar expansion, and remain satisfactory in more general cases.We also give a rapidly converging development of the exact solution, and explicitly calculate the second-order terms. The accuracy of the second-order expansion is high, and seems comparable to that given by fully numerical calculations.We have tested this analytical method by comparison with self-similar solutions, and also by comparing our results with earlier calculations on the early phases of expansion (pre-Sedov), when the mass of ejecta has not yet become negligible in comparison with the swept-up mass. We also present results on the expansion of a supernova remnant through a hot interstellar medium (ISM), which should be applicable to SNRs of large radius; recent work has shown that the ISM pressure cannot be neglected for such remnants.We hope to generalize this method of solution to more complex, e.g., non-spherically symmetric cases; the complexity of the fully numerical treatment should make analytical methods most useful in such cases

1978-10-15

303

Properties of Optically Selected Supernova Remnant Candidates in M33  

CERN Document Server

We present a sample of supernova remnant (SNR) candidates in M33 based on optical narrow band images in the Local Group Survey. We identify emission line objects that have enhanced [SII]:H{\\alpha} (> 0.4) and circular shapes using continuum-subtracted H{\\alpha}and [SII] images and produce a list of 199 SNR candidates, of which 79 are previously unknown. We classify them considering two types of criteria: their progenitor type (Type Ia and core-collapse (CC) SNRs) and their morphological type. Of the total sample, 170 are likely remnants of CC SNe and 29 are likely remnants of Type Ia SNe. We obtain a cumulative size distribution of the SNR candidates, showing that it follows a power law with an index,{\\alpha}= 2.38{\\pm}0.05 (17 < D < 50 pc). This indicates that most of the M33 SNR candidates found in this study are in the Sedov-Taylor phase, consistent with previous findings. The [SII]:H{\\alpha} distribution of the SNR candidates shows two peaks at [SII]:H{\\alpha} ~0.55 and ~0.8. Interestingly X-ray and...

Lee, Jong Hwan

2014-01-01

304

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

305

Dust in a Type Ia Supernova Progenitor: Spitzer Spectroscopy of Kepler's Supernova Remnant  

CERN Document Server

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 {\\it 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 AGB 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 IRS and IRAC data. This could imply a mixed chemistry in the atmosphere of the p...

Williams, Brian J; Reynolds, Stephen P; Ghavamian, Parviz; Blair, William P; Long, Knox S; Sankrit, Ravi

2012-01-01

306

Supernova Shock Breakout Through a Wind  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The breakout of a supernova shock wave through the progenitor star's outer envelope is expected to appear as an X-ray flash. However, if the supernova explodes inside an optically-thick wind, the breakout flash is delayed. We present a simple model for estimating the conditions at shock breakout in a wind based on the general observable quantities in the X-ray flash lightcurve: the total energy E_X, and the diffusion time after the peak, t_diff. We base the derivation on the...

Balberg, Shmuel; Loeb, Abraham

2011-01-01

307

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

CERN Document Server

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

308

Dusty Blastwaves of Two Young LMC Supernova Remnants: Constraints on Postshock Compression  

CERN Multimedia

We present results from mid-IR spectroscopic observations of two young supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) done with the {\\it Spitzer Space Telescope}. We imaged SNRs B0509-67.5 and B0519-69.0 with {\\it 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 {\\it Spitzer} IRS data to estimate the density of the postshock 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 omposition assumed, and we explore the effects of differing grain porosity on the model fits. We also analyze archival {\\it 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 ...

Williams, Brian J; Reynolds, Stephen P; Ghavamian, Parviz; Raymond, John C; Long, Knox S; Blair, William P; Sankrit, Ravi; Smith, R Chris; Points, Sean; Winkler, P Frank; Hendrick, Sean P

2011-01-01

309

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

CERN Multimedia

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

310

Gamma-ray bursts from young supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

Comets falling onto neutron stars have been suggested as a cause of {gamma}-ray bursts. In the original form of the idea, it was assumed that the neutron star remained at the centre of the Oort cloud of comets belonging to its progenitor, so that bursts would be infrequent. Here is it noted that a neutron star may well acquire a large velocity at birth, causing it to drift through the Oort cloud. As it crossed the most densely populated regions, {gamma}-ray bursts would occur frequently. Young supernova remnants may therefore be the site of some of the observed bursts, particularly the less energetic, more rapidly recurring type known as soft-{gamma}-ray repeaters. SN1987A may become a source of {gamma}-ray burst in a matter of decades. (author).

Pineault, S. (Cambridge Univ. (UK). Inst. of Astronomy)

1990-05-17

311

The radio structure of the supernova remnant IC 443  

International Nuclear Information System (INIS)

High resolution radio oberservations of the old supernova remnant IC 443 at three wavelengths are presented. The measurements with the Westerbork Synthesis Radio Telescope were made at lambda = 50.21 and 6 cm and have resolutions of 57''.3 x 148''.5, 24''.3 x 63''.0 and 12'' x 31''.1 respectively. A very detailed correlation between the optical filaments and the small scale radio features was found. The filaments are interpreted as regions that were formed by unstable cooling of the hot gas behind the shockfront. Condensation modes perpendicular to the magnetic field lines can provide the non-thermal volume emissivity enhancement needed to account for the total radio flux of IC 443 if the relativistic electrons and the magnetic fields have an interstellar origin. (orig.)

1975-04-01

312

Methanol masers in Galactic center region supernova remnants  

Science.gov (United States)

Methanol masers can be used to constrain densities and estimate kinematical distances to supernova remnants (SNRs), important parameters in cosmic ray acceleration models. With the goal of testing those models both for SNRs inside and outside the Galactic center (GC) region, we have used the Very Large Array to search for 36 GHz and 44 GHz methanol lines in Galactic SNRs. We report on the overall results of the maser search, and in particular the results of the GC SNR G1.4-0.1 in which more than 40 masers were found. They may be due to interactions between the SNR and at least two separate molecular clouds. Methanol masers were also detected in W28 and in Sgr A East.

Pihlström, Y. M.; McEwen, B. C.; Sjouwerman, L. O.

2014-05-01

313

Phosphorus in the Young Supernova Remnant Cassiopeia A  

CERN Document Server

Phosphorus ($^{31}$P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron ($^{56}$Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion.

Koo, Bon-Chul; Moon, Dae-Sik; Yoon, Sung-Chul; Raymond, John C

2013-01-01

314

Phosphorus in the young supernova remnant Cassiopeia A.  

Science.gov (United States)

Phosphorus ((31)P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here, we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron ((56)Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion. PMID:24337291

Koo, Bon-Chul; Lee, Yong-Hyun; Moon, Dae-Sik; Yoon, Sung-Chul; Raymond, John C

2013-12-13

315

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

316

Fermi LAT Observations of the Supernova Remnant W28 (G6.4-0.1)  

CERN Multimedia

We present detailed analysis of the two gamma-ray sources,1FGL J1801.3-2322c and 1FGL J1800.5-2359c,that have been found toward the supernova remnant(SNR) W28 with the Large Area Telescope(LAT) on board the Fermi Gamma-ray Space Telescope.1FGL J1801.3-2322c is found to be an extended source within the boundary of SNR W28,and to extensively overlap with the TeV gamma-ray source HESS J1801-233,which is associated with a dense molecular cloud interacting with the supernova remnant.The gamma-ray spectrum measured with LAT from 0.2--100 GeV can be described by a broken power-law function with a break of ~1GeV,and photon indices of 2.09$\\pm$0.08(stat)$\\pm$0.28(sys) below the break and 2.74$\\pm$0.06(stat)$\\pm$0.09(sys) above the break.Given the clear association between HESS J1801-233 and the shocked molecular cloud and a smoothly connected spectrum in the GeV--TeV band,we consider the origin of the gamma-ray emission in both GeV and TeV ranges to be the interaction between particles accelerated in the SNR and the m...

Abdo, A A

2010-01-01

317

RADIOACTIVE SCANDIUM IN THE YOUNGEST GALACTIC SUPERNOVA REMNANT G1.9+0.3  

International Nuclear Information System (INIS)

We report the discovery of thermal X-ray emission from the youngest Galactic supernova remnant G1.9+0.3, from a 237 ks Chandra observation. We detect strong K? 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) x 10-5 M sun of 44Ti, in the range predicted for both Type Ia and core-collapse supernovae (SNe), but somewhat smaller than the 2 x 10-4 M sun reported for Cas A. The line spectrum indicates supersolar abundances. The Fe emission has a width of about 28,000 km s-1, consistent with an age of ?100 yr and with the inferred mean shock velocity of 14,000 km s-1 deduced assuming a distance of 8.5 kpc. Most thermal emission comes from regions of lower X-ray but higher radio surface brightness. Deeper observations should allow more detailed spatial mapping of 44Sc, with significant implications for models of nucleosynthesis in Type Ia SNe.

2010-12-01

318

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

319

Discovery of a pre-existing molecular filament associated with supernova remnant G127.1+0.5  

CERN Document Server

We performed millimeter observations in CO lines toward the supernova remnant (SNR) G127.1+0.5. We found a molecular filament at 4--13 km s$^{-1}$ consisting of two distinct parts: a straight part coming out of the remnant region and a curved part in the remnant region. The curved part is coincides well with the bright SNR shell detected in 1420 MHz radio continuum and mid-infrared observations in the northeastern region. In addition, redshifted line wing broadening is found only in the curved part of the molecular filament, which indicates a physical interaction. These provide strong evidences, for the first time, to confirm the association between an SNR and a pre-existing long molecular filament. Multi-band observations in the northeastern remnant shell could be explained by the interaction between the remnant shock and the dense molecular filament. RADEX radiative transfer modeling of the quiet and shocked components yield physical conditions consistent with the passage of a non-dissociative J-type shock....

Zhou, Xin; Fang, Min; Su, Yang

2014-01-01

320

Powerful Tools for Dissecting Supernova Remnants Observed with Chandra  

Science.gov (United States)

We introduce powerful new methods to quantify X-ray morphology of supernova remnants observed with Chandra. We demonstrate application of three techniques -- a power-ratio method, two-point correlation, and wavelet-transform analysis -- to archival ACIS observations of twenty galactic SNRs of all types and a variety of ages to measure chemical segregation and mixing, distribution asymmetries, and local substructure. Detailed comparison between sources provides crucial insights regarding the nature of the explosion, the effects of heating and dense environments, and particle acceleration properties. For each remnant, we have created individual images of observed spectral features (emission lines, thermal and non-thermal emission). Using two-point correlation, we disentangle the thermal and non-thermal emitting regions, and we measure with great accuracy the sizes and locations of thermal and non-thermal clumps with wavelet-transform analysis. The non-thermal continuum is located predominantly around the rim of our sources, and it has great excess power at small scales compared to the thermal component. Application of our methods to radio data reveals how the size of non-thermal emitting regions changes as a function of photon energy, which provides crucial insight to understand the magnetic-field properties and particle acceleration mechanisms. We extract XMM-Newton spectra of the regions with and without line emission as identified by the wavelet-transform analysis. Detailed knowledge of the X-ray substructure enables much more precise ejecta mass estimates than any previous SNR studies, key to constraining the supernova explosion histories. Additionally, we map rigorously the temperature and ion intensity variation within each source. Using these methods, we distinguish whether asymmetric chemical distributions arise from inhomogeneous heating or from an anisotropic explosion. In brief, we present three mathematical techniques that are superbly suited for analysis of high-resolution X-ray images, and we show their use for probing many outstanding questions that are vital to advance SNR understanding.

Lopez, Laura A.; Ramirez-Ruiz, E.; Pooley, D.; Huppenkothen, D.

2008-03-01

 
 
 
 
321

A search for compact decametric radio sources in supernova remnants using the interplanetary scintillation technique  

Science.gov (United States)

Interplanetary scintillation observations of eleven supernova remnants and the pulsar J1939+2134, around which the existence of a supernova remnant remains obscure, were carried out with the largest in the world decameter radio telescope UTR-2 at 20, 25 and 30 MHz to determine if any of them contain compact radio sources with the angular size ?J1939+2134 were observed. Apart from the Crab Nebula, we have not detected a compact radio source in supernova remnants with the angular size ?<5? and the flux density more than 10 Jy. The observations do not confirm the existence of the low frequency compact source in Cassiopeia A that has remained controversial.

Kalinichenko, N. N.

2009-02-01

322

Nonthermal Radiation of Young Supernova Remnants: The Case of CAS A  

Science.gov (United States)

The processes responsible for the broadband radiation of the young supernova remnant Cas A are explored by using a new code that is designed for a detailed treatment of the diffusive shock acceleration of particles in the nonlinear regime. The model is based on spherically symmetric hydrodynamic equations complemented with transport equations for relativistic particles. Electrons, protons, and the oxygen ions accelerated by forward and reverse shocks are included in the numerical calculations. We show that the available multi-wavelength observations in the radio, X-ray, and gamma-ray bands can be best explained by invoking particle acceleration by both forward and reversed shocks. Although the TeV gamma-ray observations can be interpreted by interactions of both accelerated electrons and protons/ions, the measurements by Fermi Large Area Telescope at energies below 1 GeV give a tentative preference to the hadronic origin of gamma-rays. Then, the acceleration efficiency in this source, despite the previous claims, should be very high; 25% of the explosion energy (or approximately 3 × 1050 erg) should already be converted to cosmic rays, mainly by the forward shock. At the same time, the model calculations do not provide extension of the maximum energy of accelerated protons beyond 100 TeV. In this model, the acceleration of electrons is dominated by the reverse shock; the required 1048 erg can be achieved under the assumption that the injection of electrons (positrons) is supported by the radioactive decay of 44Ti.

Zirakashvili, V. N.; Aharonian, F. A.; Yang, R.; Oña-Wilhelmi, E.; Tuffs, R. J.

2014-04-01

323

Fermi Large Area Telescope observations of the supernova remnant HESS J1731-347  

Science.gov (United States)

Context. HESS J1731-347 has been identified as one of the few TeV-bright shell-type supernova remnants (SNRs). These remnants are dominated by nonthermal emission, and the nature of TeV emission has been continuously debated for nearly a decade. Aims: We carry out the detailed modeling of the radio to ?-ray spectrum of HESS J1731-347 to constrain the magnetic field and energetic particles sources, which we compare with those of the other TeV-bright shell-type SNRs explored before. Methods: Four years of data from Fermi Large Area Telescope (LAT) observations for regions around this remnant are analyzed, leading to no detection correlated with the source discovered in the TeV band. The Markov chain Monte Carlo method is used to constrain parameters of one-zone models for the overall emission spectrum. Results: Based on the 99.9% upper limits of fluxes in the GeV range, one-zone hadronic models with an energetic proton spectral slope greater than 1.8 can be ruled out, which favors a leptonic origin for the ?-ray emission, making this remnant a sibling of the brightest TeV SNR RX J1713.7-3946, the Vela Junior SNR RX J0852.0-4622, and RCW 86. The best-fit leptonic model has an electron spectral slope of 1.8 and a magnetic field of ~30 ?G, which is at least a factor of 2 higher than those of RX J1713.7-3946 and RX J0852.0-4622, posing a challenge to the distance estimate and/or the energy equipartition between energetic electrons and the magnetic field of this source. A measurement of the shock speed will address this challenge and has implications on the magnetic field evolution and electron acceleration driven by shocks of SNRs.

Yang, Rui-zhi; Zhang, Xiao; Yuan, Qiang; Liu, Siming

2014-07-01

324

Two Radio Supernova Remnants Discovered in the Outer Galaxy  

CERN Multimedia

We report on the discovery of two supernova remnants (SNRs) designated G152.4-2.1 and G190.9-2.2, using Canadian Galactic Plane Survey data. The aims of this paper are, first, to present evidence that favours the classification of both sources as SNRs, and, second, to describe basic parameters (integrated flux density, spectrum, and polarization) as well as properties (morphology, line-of-sight velocity, distance and physical size) to facilitate and motivate future observations. Spectral and polarization parameters are derived from multiwavelength data from existing radio surveys carried out at wavelengths between 6 and 92cm. In particular for the source G152.4-2.1 we also use new observations at 11cm done with the Effelsberg 100m telescope. The interstellar medium around the discovered sources is analyzed using 1-arcminute line data from neutral hydrogen (HI) and 45-arcsecond 12CO(J=1-0). G152.4-2.1 is a barrel shaped SNR with two opposed radio-bright polarized flanks on the North and South. The remnant, whi...

Foster, Tyler; Reich, Wolfgang; Kothes, Roland; West, Jennifer; 10.1051/0004-6361/201220362

2013-01-01

325

Rejuvenating the shells of supernova remnants by pulsar winds  

CERN Multimedia

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

326

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

327

High-Resolution X-Ray Spectroscopy of the Galactic Supernova Remnant Puppis A with the XMM-Newton RGS  

Science.gov (United States)

We present high-resolution X-ray spectra of cloud-shock interaction regions in the eastern and northern rims of the Galactic supernova remnant Puppis A, using the Reflection Grating Spectrometer onboard the XMM-Newton satellite. A number of emission lines including K(alpha) triplets of He-like N, O , and Ne are clearly resolved for the first time. Intensity ratios of forbidden to resonance lines in the triplets are found to be higher than predictions by thermal emission models having plausible plasma parameters. The anomalous line ratios cannot be reproduced by effects of resonance scattering, recombination, or inner-shell ionization processes, but could be explained by charge-exchange emission that should arise at interfaces between the cold/warm clouds and the hot plasma. Our observations thus provide observational support for charge-exchange X-ray emission in supernova remnants.

Katsuda, Satoru; Tsunemi, Hiroshi; Mori, Koji; Uchida, Hiroyuki; Petre, Robert; Yamada, Shinya; Akamatsu, Hiroki; Konami, Saori; Tamagawa, Toru

2012-01-01

328

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

International Nuclear Information System (INIS)

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

329

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

330

Multifrequency Studies of Bright Radio Supernova Remnants; 3, X-Ray and Radio Observations of 3C 397  

CERN Document Server

Radio-bright, presumably young supernova remnants offer the opportunity of studying strong-shock physics and the nature of the interaction of ejected material with the surrounding medium. We use VLA and ROSAT images of the radio-bright supernova remnant 3C 397 (G41.1--0.3) to examine the shock structure in both thermal X-ray emission and nonthermal radio emission. The unusual rectangular morphology can be seen in VLA maps at 20 and 6 cm wavelength at a resolution of 6", and in ROSAT HRI images. The X-ray images resemble the radio strongly, except for a small, possibly un resolved X-ray hot spot near the center. There is no variation in the X-ray hardness ratio from ROSAT Position Sensitive Proportional Counter data across the remnant, suggesting that at least between 0.4 and 2 keV, the interior emission is not different in character from that in the bright shell regions. Thus 3C 397 is not a member of the ``thermal composite'' or ``mixed-morphology'' class (Rho 1998). The remnant is unpolarized at 20 cm, and ...

Dyer, K K

1999-01-01

331

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

332

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

CERN Document Server

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

333

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

2011-01-01

334

Hard X-ray emission and $^{44}$Ti line features of Tycho Supernova Remnant  

CERN Multimedia

A deep hard X-ray survey of the INTEGRAL satellite first detected the non-thermal emission up to 90 keV in the Tycho supernova (SN) remnant. Its 3 -- 100 keV spectrum is fitted with a thermal bremsstrahlung of $kT\\sim 0.81\\pm 0.45$ keV plus a power-law model of $\\Gamma \\sim 3.01\\pm 0.16$. Based on the diffusive shock acceleration theory, this non-thermal emission, together with radio measurements, implies that Tycho remnant may not accelerate protons up to $>$PeV but hundreds TeV. Only heavier nuclei may be accelerated to the cosmic ray spectral "knee". In addition, we search for soft gamma-ray lines at 67.9 and 78.4 keV coming from the decay of radioactive $^{44}$Ti in Tycho remnant by INTEGRAL. A bump feature in the 60-90 keV energy band, potentially associated with the $^{44}$Ti line emission, is found with a marginal significance level of $\\sim$ 2.6 $\\sigma$. The corresponding 3 $\\sigma$ upper limit on the $^{44}$Ti line flux amounts to 1.5 $\\times$ 10$^{-5}$ ph cm$^{-2}$ s$^{-1}$. Implications on the pro...

Wang, Wei

2014-01-01

335

Identification Campaign of Supernova Remnant Candidates in the Milky Way. II. X-Ray Studies of G38.7-1.4  

Science.gov (United States)

We report on XMM-Newton and Chandra observations of the Galactic supernova remnant candidate G38.7-1.4, together with complementary radio, infrared, and ?-ray data. An approximately elliptical X-ray structure is found to be well correlated with a radio shell as seen by the Very Large Array. The X-ray spectrum of G38.7-1.4 can be well described by an absorbed collisional ionization equilibrium plasma model, which suggests the plasma is shock heated. Based on the morphology and the spectral behavior, we suggest that G38.7-1.4 is indeed a supernova remnant belonging to a mix-morphology category.

Huang, R. H. H.; Wu, J. H. K.; Hui, C. Y.; Seo, K. A.; Trepl, L.; Kong, A. K. H.

2014-04-01

336

Optical Imaging and Spectroscopic Observation of the Galactic Supernova Remnant G85.9-0.6  

CERN Document Server

Optical CCD imaging with H$\\alpha$ and [SII] filters and spectroscopic observations of the galactic supernova remnant G85.9-0.6 have been performed for the first time. The CCD image data are taken with the 1.5m Russian-Turkish Telescope (RTT150) at TUBITAK National Observatory (TUG) and spectral data are taken with the Bok 2.3 m telescope on Kitt Peak, AZ. The images are taken with narrow-band interference filters H$\\alpha$, [SII] and their continuum. [SII]/H$\\alpha$ ratio image is performed. The ratio obtained from [SII]/H$\\alpha$ is found to be $\\sim$0.42, indicating that the remnant interacts with HII regions. G85.9-0.6 shows diffuse-shell morphology. [SII]$\\lambda\\lambda 6716/6731$ average flux ratio is calculated from the spectra, and the electron density $N_{e}$ is obtained to be 395 $cm^{-3}$. From [OIII]/H$\\beta$ ratio, shock velocity has been estimated, pre-shock density of $n_{c}=14$ $cm^{-3}$, explosion energy of $E=9.2\\times10^{50}$ ergs, interstellar extinction of $E(B-V)=0.28$, and neutral hydro...

Gok, F; Aktekin, E; Guver, T; Ercan, N; 10.1007/s10509-009-0150-3

2009-01-01

337

Separating Thermal and Non-Thermal X-Rays in Supernova Remnants II: Spatially Resolved Fits to SN1006 AD  

CERN Multimedia

We present a spatially resolved spectral analysis of full ASCA observations of the remnant of the supernova of 1006 AD. This remnant shows both nonthermal X-ray emission from bright limbs, generally interpreted as synchrotron emission from the loss-steepened tail of the nonthermal electron population also responsible for radio emission, and thermal emission from elsewhere in the remnant. In earlier work, we showed that the spatially integrated spectrum was well described by a theoretical synchrotron model in which shock acceleration of electrons was limited by escape, in combination with thermal models indicating high levels of iron from ejecta. Here we use new spatially resolved subsets of the earlier theoretical nonthermal models for the analysis. We find that emission from the bright limbs remains well described by those models, and refine the values for the characteristic break frequency. We show that differences between the northeast and southwest nonthermal limbs are small, too small to account easily f...

Dyer, K K; Borkowski, K J

2004-01-01

338

Laboratory Simulation of Collisionless Coupling Between Supernova Remnants and Magnetized Interstellar Medium.  

Science.gov (United States)

The method and results of laboratory simulation of the collisionless deceleration of supernova remnants in experiments on the interaction of a laser produced plasma cloud with a highly ionized magnetized background are presented. The processes and conditi...

Y. P. Zakharov A. M. Orishich A. G. Ponomarenko V. G. Posukh V. N. Syntnikov

1986-01-01

339

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

International Nuclear Information System (INIS)

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 10-11 ergs cm-2 s-1 near the Earth. The measured source spectrum implies a plasma temperature of approx.4 x 106 K and X-ray luminosity in the 0.4--2 keV band of approx.1037 ergs s-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-1 and a supernova age of approx.2300 yr, in good agreement with the age derived from the radio observations

1980-04-15

340

The OH (1720 MHz) Supernova Remnant Masers in W28: MERLIN and VLBA Polarization Observations  

Science.gov (United States)

Full-polarization MERLIN and VLBA observations of the 1720 MHz maser emission from the OH molecule in the supernova remnant W28 are presented. Zeeman splitting (|B|~0.75 mG) has been directly resolved between right- and left-circularly polarized spectra for the first time. Linear polarization position angles and circular polarization Zeeman splitting observed in the maser emission permit interpretation of a comprehensive picture of the magnetic field at the supernova/molecular cloud interface marked by the masers. We find the post-SNR shock magnetic field to be well ordered over the ~1 pc covered by the maser region (compared with the approximately 30 pc diameter of the entire SNR) and well aligned with the shock front that is traced by synchrotron radiation and molecular emission. Based on MERLIN data having a resolution of 200 mas and VLBA data with a resolution of 15 mas, the masers are measured to have deconvolved angular sizes of 90-350 mas (225-875 AU) with compact cores 20 mas (50 AU) in size, consistent with theoretical expectation and previous observations.

Hoffman, Ian M.; Goss, W. M.; Brogan, C. L.; Claussen, M. J.

2005-02-01

 
 
 
 
341

The OH (1720 MHz) Supernova Remnant Masers in W28: MERLIN and VLBA Polarization Observations  

CERN Document Server

Full-polarization MERLIN and VLBA observations of the 1720 MHz maser emission from the OH molecule in the supernova remnant W28 are presented. Zeeman splitting (|B| \\approx 0.75 mG) has been directly resolved between right- and left-circularly polarized spectra for the first time. Linear-polarization position angles and circular-polarization Zeeman splitting observed in the maser emission permit interpretation of a comprehensive picture of the magnetic field at the supernova/molecular cloud interface marked by the masers. We find the post-SNR-shock magnetic field to be well-ordered over the ~1 pc covered by the maser region (compared with the approximately 30-pc diameter of the entire SNR) and well-aligned with the shock front that is traced by synchrotron radiation and molecular emission. Based on MERLIN data having a resolution of 200 mas and VLBA data with a resolution of 15 mas, the masers are measured to have deconvolved angular sizes of 90 to 350 mas (225 to 875 AU) with compact cores 20 mas (50 AU) in ...

Hoffman, I M; Brogan, C L; Claussen, M J; Hoffman, Ian M.

2004-01-01

342

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

343

Physical processes and infrared emission from the Cassiopeia A supernova remnant  

International Nuclear Information System (INIS)

IRAS 12-100 micron data on the Cas A remnant are presented, and various physical mechanisms and astrophysical sites that may contribute to the observed infrared emission are analyzed. The contributions of various sources of infrared emission to the IRAS fluxes are found to be small. The residual infrared emission is attributed to thermal emission from dust which is swept up by the expanding supernova blast wave and collisionally heated by the postshock X-ray emitting gas. The calculations are consistent with a shock velocity of 1800 km/s and a preshock gas density of about 2/cu cm. The mass of the swept-up gas is about 0.6 solar mass. An excess of 12 micron thermal emission in the spectrum of Cas A suggests the presence of very small particles in the preshocked gas. 48 references

1987-01-01

344

Enhanced Cosmic Ray Flux and Ionization for Star Formation in Molecular Clouds Interacting with Supernova Remnants  

CERN Document Server

Molecular clouds interacting with supernova remnants may be subject to a greatly enhanced irradiation by cosmic rays produced at the shocked interface between the ejecta and the molecular gas. Over the past decade, broad-band observations have provided important clues about these relativistic particles and indicate that they may dominate over the locally observed cosmic-ray population by a significant amount. In this paper, we estimate the enhancement and find that the cosmic ray energy density can be up to $\\sim$1000 times larger in the molecular cloud than in the field. This enhancement can last for a few Myr and leads to a corresponding increase in the ionization fraction, which has important consequences for star formation. Ionization fractions in] molecular cloud cores determine, in part, the rate of ambipolar diffusion, an important process in core formation and pre-collapse evolution. Ionization fractions in newly formed circumstellar disks affect the magneto-rotational instability mechanism, which in ...

Fatuzzo, M; Melia, F

2006-01-01

345

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

CERN Document Server

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

346

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

347

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

International Nuclear Information System (INIS)

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 arcsec"2 (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

348

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

International Nuclear Information System (INIS)

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 10_3_6 ergs per second. The current shock velocity is 3400 +- 140 kilometers per second. An initial blast energy is found of 2.5 x 10_5_1 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

349

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

CERN Document Server

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

350

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

CERN Multimedia

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

351

A Multiwavelength Database of Magellanic Cloud Supernova Remnants  

Science.gov (United States)

Supernovae (SNe), through their diffuse supernova remnants (SNRs), are primarily responsible for the injection of energy and heavy elements into the interstellar medium (ISM). SNe provide most of the hot gas component of the ISM, and through collective inputs to structures such as superbubbles and supergiant shells, can transfer hot gas into a galaxy halo. The energy and heavy elements influence future generations of star formation in a galaxy and have a profound effect on galaxy evolution. We have undertaken a long-term multiwavelength study of SNRs in the Magellanic Clouds (MCs). These galaxies contain extraordinary samples of SNRs at a wide variety of types, ages, evolutionary stages, and environments. The known, common distances and low obscuration of the MCs allows their SNRs to be studied as members of an increasingly well-understood population. The current generation of instruments, including the Chandra and XMM X-ray satellites and the Hubble and Spitzer Space Telescopes, have allowed high-resolution examinations of these SNRs at levels comparable to those for Galactic objects. Crucially, new surveys of the MCs with the Australia Telescope Compact Array in radio, and the Magellanic Clouds Emission-Line Survey at CTIO, have providded a wealth of data on each of these objects. We have used these resources to build up a database of information on the Magellanic Cloud SNRs, in order to make the data and findings easily accessible to other researchers. We here present the current state of the database and future plans for the inclusion of more information. The authors thank NASA's LTSA grant NNX08AM54G for support of this long-term project.

Murphy Williams, Rosa Nina; Dickel, J. R.; Chu, Y.; Points, S.; Winkler, F.; Johnson, M.; Lodder, K.

2010-01-01

352

G7.7-3.7 - a supernova remnant with a high degree of radio polarization  

International Nuclear Information System (INIS)

Total power and polarization measurements at 843 MHz and 8.4 GHz are presented for the shell-type supernova remnant G7.7-3.7. The remnant is highly polarized at 8.4 GHz; a feature with an unusually steep spectrum may be unrelated to the SNR. (author)

1986-12-01

353

The Slow X-Ray Expansion of the Northwestern Rim of the Supernova Remnant RX J0852.0-4622  

CERN Multimedia

The detection of radioactive decay line of 44Ti provides a unique evidence that the gamma-ray source is a young (< 1,000 yr) supernova remnant because of its short lifetime of about 90 yr. Only two Galactic remnants, Cassiopeia A and RX J0852.0-4622, are hitherto reported to be the 44Ti line emitter, although the detection from the latter has been debated. Here we report on an expansion measurement of the northwestern rim of RX J0852.0-4622 obtained with X-ray observations separated by 6.5 yr. The expansion rate is derived to be 0.023+/-0.006% that is about five times lower than those of young historical remnants. Such a slow expansion suggests that RX J0852.0-4622 is not a young remnant as has been expected. We estimate the age of 1,700-4,300 yr of this remnant depending on its evolutionary stage. Assuming a high shock speed of about 3000 km/sec, which is suggested by the detection of non-thermal X-ray radiation, the distance of about 750 pc to this remnant is also derived.

Katsuda, S; Mori, K

2008-01-01

354

The visibility of shell-type supernova remnants in gamma rays  

International Nuclear Information System (INIS)

The question of the origin of the cosmic radiation (CR) is a continuing one. The idea that the shocks from supernova remnants (SNR) expanding into the interstellar medium (ISM) accelerate CR is still a popular one but a number of authors have drawn attention to the fact that the experimental evidence for the presence of gamma rays from the expected interaction of CR with gas in the remnant is poor. Indeed, it is claimed that many SNR are not 'seen' in GeV or TeV gamma rays, whereas 'they should have been'. We have looked at this problem and we conclude that the idea of CR production in SNR cannot be faulted in this way, if the evacuation of ambient gas by the stellar wind of the progenitor star and, frequently, by associated earlier close-by SN, is taken into account; such phenomena are expected for the important type II SN which result from very massive stars and which provide the SNR which are thought to accelerate CR. Other SNR have, apparently, been seen and the interaction of SNR-accelerated particles with adjacent molecular clouds has been deemed responsible. However, we worry about this interpretation because of the slow progress of the SNR shock through such clouds, although electron-effects may, indeed, contribute. This paper is devoted mainly to the visibility of nearby (within about1 kpc) SNR in gamma rays although many of the arguments also relate to remote SNR. For the nearby SNR another problem enters the scene: the large angular spread of the remnant. It is especially important for the old SNR, where cosmic rays have already diffused to a large distance from the SNR centre. We have also examined the effect of the 'anomalous diffusion' of CR propagation in the non-homogeneous interstellar medium on the visibility of SNR for gamma rays of different energies

2003-04-01

355

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

2006-01-01

356

The likely Fermi Detection of the Supernova Remnant RCW 103  

CERN Document Server

We report on the results from our $\\gamma$-ray analysis of the supernova remnant (SNR) RCW 103 region. The data were taken with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. An extended source is found at a position consistent with that of RCW 103, and its emission was only detected above 1 GeV (10$\\sigma$ significance), having a power-law spectrum with a photon index of 2.0$\\pm$0.1. We obtain its 1--300 GeV spectrum, and the total flux gives a luminosity of 8.3$\\times 10^{33}$ erg s$^{-1}$ at a source distance of 3.3 kpc. Given the positional coincidence and property similarities of this source with other SNRs, we identify it as the likely Fermi $\\gamma$-ray counterpart to RCW 103. Including radio measurements of RCW 103, the spectral energy distribution (SED) is modeled by considering emission mechanisms based on both hadronic and leptonic scenarios. We find that models in the two scenarios can reproduce the observed SED, although in the hadronic scenario, the total proton energy (5...

Xing, Yi; Zhang, Xiao; Chen, Yang

2013-01-01

357

Fermi LAT Observation of Supernova Remnant HB9  

CERN Multimedia

A 5.5-year Fermi LAT gamma-ray observation shows significant extended emission at the position of the supernova remnant HB9 (G160.9+2.6). The significance of the detection above the background for photon energies above 0.2 GeV is 21-sigma. The gamma-ray flux above 0.2 GeV is 3.2E-8 photons/cm2/s, and the corresponding luminosity above 1 GeV is 1.5E33 erg/s (for a source distance of 1 kpc). The gamma-ray spectrum of the source is best described by a power-law with an exponential cutoff in energy (E^(-s) exp(-E/Ec)) with photon index s ~ 1.7 and cutoff energy Ec ~ 2.5 GeV. The spectrum is consistent with both leptonic and hadronic models, and the relevant physical parameters in each case are derived. More studies on the ambient density in the region of HB9 should be carried out to rule out or confirm hadronic and non-thermal bremsstrahlung scenarios for the gamma-ray emission.

Araya, Miguel

2014-01-01

358

Echelle observations of supernova remnants in the Magellanic Clouds  

International Nuclear Information System (INIS)

Long-slit echelle observations of eight cataloged supernova remnants (SNRs) in the Magellanic Clouds have been obtained: N19 in the SMC, and N11L, N49, N63A, N86, N135, N157B, and N206 in the LMC. These SNRs were selected to cover a large range in morphology and interstellar environment. The H-alpha and forbidden N II emission-line images provide a homogeneous set of data on the large-scale kinematics of the line-emitting gas in evolved SNRs. The data have been used to simulate integrated velocity profiles in order to estimate the importance of foreground nebular contamination on the emission spectra of SNRs in distant galaxies, and for comparison with the luminous SNR candidates in the giant H II regions in M101. Five unconfirmed SNR candidates have also been observed: N66 in the SMC, and the nonthermal radio sources 0525-66.3 and 0526-66.2, the superbubble 0536-692, and N70 in the LMC. The presence of a SNR within the H II region N66 is confirmed, and SNRs in the nonthermal radio sources 0525-66.3 and 0526-66.2 have been ruled out. The nature of 0536-692 and N70 remains ambiguous. 53 references

1988-01-01

359

Photoionization of Galactic Halo Gas by Old Supernova Remnants  

CERN Multimedia

We present new calculations on the contribution from cooling hot gas to the photoionization of warm ionized gas in the Galaxy. We show that hot gas in cooling supernova remnants (SNRs) is an important source of photoionization, particularly for gas in the halo. We find that in many regions at high latitude this source is adequate to account for the observed ionization so there is no need to find ways to transport stellar photons from the disk. The flux from cooling SNRs sets a floor on the ionization along any line of sight. Our model flux is also shown to be consistent with the diffuse soft X-ray background and with soft X-ray observations of external galaxies. We consider the ionization of the clouds observed towards the halo star HD 93521, for which there are no O stars close to the line of sight. We show that the observed ionization can be explained successfully by our model EUV/soft X-ray flux from cooling hot gas. In particular, we can match the H alpha intensity, the S++/S+ ratio, and the C+* column. F...

Slavin, J D; Hollenbach, D J; Slavin, Jonathan D.; Kee, Christopher F. Mc; Hollenbach, David J.

2000-01-01

360

Unveiling the true age of the 'Vela Junior' supernova remnant  

International Nuclear Information System (INIS)

The supernova remnant G266.1-1.2 has attracted considerable interest owing to its possible detection in the 1.156 MeV line of 44Ti by COMPTEL. If this controversial result is confirmed, G266.1-1.2 well deserves the 'Vela Junior' nickname, since the observed gamma-ray line flux implies a very small age (?700 years) and distance (?200 pc). We discuss the implications of recent X-ray observations on the SNR distance and age. Two sources were detected with BeppoSAX close to the geometrical center of G266.1-1.2. Independent of which one is the neutron star associated to G266.1-1.2, their properties imply an age of a few 10,000 years and a distance greater than one kpc. We also present a preliminary analysis of the brightest portion of the SNR shell, in which significant upper limits on the presence of X-ray emission lines are derived

2001-10-07

 
 
 
 
361

Discovery of New Interacting Supernova Remnants in the Inner Galaxy  

CERN Multimedia

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

362

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

2011-01-01

363

Infrared Spectral Mapping of Supernova Remnants. I. N63A and Its Environment  

Science.gov (United States)

We present Spitzer Space Telescope spectra of the supernova remnant (SNR) N63A and its native H II region N63 in the Large Magellanic Cloud. We measure nebular fine-structure lines, H2 lines, and polycyclic aromatic hydrocarbons (PAHs). The lines contribute half of the flux in the Spitzer 24 ?m image of N63A shocked lobes, but only Electron densities are low everywhere; the differences in mid-IR line ratios separate N63A plasma and its high-excitation surroundings from N63A low-excitation optical lobes. We compare the observed line fluxes and ratios within N63A's shocked lobes and plasma with the predictions from models for moderate and fast shocks to constrain pre-shock densities and shock velocities. N63A's photoionized lobe contains a warm photodissociation region in pressure equilibrium with optically ionized gas. We apply a physical dust model to our spectra supplemented by MIPS photometry. We derive the intensity of radiation heating the dust, the mass fraction due to PAHs, and the masses of dust within our sampled regions and of cooler grains in the diffuse interstellar medium. N63A's shocked lobes and plasma contain ~0.07 M ? of hot grains, comparable to amounts in other SNRs. Within N63A there is ~0.7 M ? of warm grains exposed to >=100 times the intensity of the local interstellar radiation field. Within the regions, 92% of the total dust mass resides in cool grains emitting <=27% of their mid-IR luminosity. In loving memory of Sylvie Caulet-Maugendre: "I used to believe in forever, but forever is too good to be true." A. A. Milne, Winnie-the-Pooh.

Caulet, Adeline; Williams, Rosa M.

2012-12-01

364

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We show that (1) the newly discovered supernova remnant (SNR), GRO J0852--4642/RX J0852.0--4622, was 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. The first conclusion is based on the fact that the remnant is currently expanding too ...

Chen, Wan; Gehrels, Neil

1998-01-01

365

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

CERN Document Server

In this study, we treat the 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 contr...

Fujita, Yutaka; Yamazaki, Ryo

2013-01-01

366

Determination of acceleration mechanism characteristics directly and nonparametrically from observations: Application to supernova remnants  

Science.gov (United States)

We have developed an inversion method for determination of the characteristics of the acceleration mechanism directly and nonparametrically from observations, in contrast to the usual forward fitting of parametric model variables to observations. In two recent papers [V. Petrosian and Q. Chen, Astrophys. J. 712, L131 (2010); Q. Chen and V. Petrosian, Astrophys. J. 777, 33 (2013)], we demonstrated 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 electron spectra deduced from the observed nonthermal radiation from SNRs and the spectrum of the cosmic ray electrons observed near the Earth. These spectra 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 crucial roles in both direct acceleration by turbulence and in high Mach number shocks. Assuming that the average electron spectrum deduced from a few well-known SNRs is representative of those in the solar neighborhood, we find interesting discrepancies between our deduced forms for these coefficients and those expected from well-known wave-particle interactions. This may indicate that the standard assumptions made in the treatment of shock acceleration need revision. In particular, the escape of particles from SNRs may be more complex than generally assumed.

Petrosian, Vahé; Chen, Qingrong

2014-05-01

367

Supernova Remnant Kes 17: Efficient Cosmic Ray Accelerator inside a Molecular Cloud  

CERN Document Server

Supernova remnant Kes 17 (SNR G304.6+0.1) is one of a few but growing number of remnants detected across the electromagnetic spectrum. In this paper, we analyze recent radio, X-ray, and gamma-ray observations of this object, determining that efficient cosmic ray acceleration is required to explain its broadband non-thermal spectrum. These observations also suggest that Kes 17 is expanding inside a molecular cloud, though our determination of its age depends on whether thermal conduction or clump evaporation is primarily responsible for its center-filled thermal X-ray morphology. Evidence for efficient cosmic ray acceleration in Kes 17 supports recent theoretical work that the strong magnetic field, turbulence, and clumpy nature of molecular clouds enhances cosmic ray production in supernova remnants. While additional observations are needed to confirm this interpretation, further study of Kes 17 is important for understanding how cosmic rays are accelerated in supernova remnants.

Gelfand, Joseph D; Slane, Patrick O; Temim, Tea; Hughes, John P; Rakowski, Cara

2013-01-01

368

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

369

G65.2+5.7: A Thermal Composite Supernova Remnant With a Cool Shell  

CERN Multimedia

This paper presents archival ROSAT PSPC observations of the G65.2+5.7 supernova remnant (also known as G65.3+5.7). Little material obscures this remnant and so it was well observed, even at the softest end of ROSAT's bandpass (~0.11 to 0.28 keV). These soft X-ray images reveal the remnant's centrally-filled morphology which, in combination with existing radio frequency observations, places G65.2+5.7 in the thermal composite (mixed morphology) class of supernova remnants. Not only might G65.2+5.7 be the oldest known thermal composite supernova remnant, but owing to its optically revealed cool, dense shell, this remnant supports the proposal that thermal composite supernova remnants lack X-ray bright shells because they have evolved beyond the adiabatic phase. These observations also reveal a slightly extended point source centered on RA = 19h 36m 46s, dec = 30deg 40' 07'' and extending 6.5 arcmin in radius in the band 67 map. The source of this emission has yet to be discovered, as there is no known pulsar at ...

Shelton, R L; Petre, R

2004-01-01

370

The visibility of shell-type supernova remnants in gamma rays  

CERN Document Server

The idea that the shocks from supernova remnants (SNR) expanding into the interstellar medium (ISM) accelerate CR is still popular one but a number of authors have drawn attention to the fact that the experimental evidence for the presence of gamma rays from the expected interaction of CR with gas in the remnant is poor. Indeed, it is claimed that many SNR are not `seen' in GeV or TeV gamma rays, whereas `they should have been'. We have looked at this problem and we conclude that the idea of CR production in SNR cannot be faulted in this way, if the evacuation of ambient gas by the stellar wind of the progenitor star and, frequently, by associated earlier close-by SN, is taken into account; such phenomena are expected for the important Type II SN which result from very massive stars. Other SNR have, apparently, been seen and the interaction of SNR-accelerated particles with adjacent molecular clouds has been deemed responsible. However, we worry about this interpretation because of the slow progress of the SN...

Erlykin, A D

2003-01-01

371

0103-72.6: A New Oxygen-Rich Supernova Remnant in the Small Magellanic Cloud  

CERN Document Server

0103$-$72.6, the second brightest X-ray supernova remnant (SNR) in the Small Magellanic Cloud (SMC), has been observed with the {\\it Chandra X-Ray Observatory}. Our {\\it Chandra} observation unambiguously resolves the X-ray emission into a nearly complete, remarkably circular shell surrounding bright clumpy emission in the center of the remnant. The observed X-ray spectrum for the central region is evidently dominated by emission from reverse shock-heated metal-rich ejecta. Elemental abundances in this ejecta material are particularly enhanced in oxygen and neon, while less prominent in the heavier elements Si, S, and Fe. We thus propose that 0103$-$72.6 is a new ``oxygen-rich'' SNR, making it only the second member of the class in the SMC. The outer shell is the limb-brightened, soft X-ray emission from the swept-up SMC interstellar medium. The presence of O-rich ejecta and the SNR's location within an H{\\small II} region attest to a massive star core-collapse origin for 0103$-$72.6. The elemental abundance ...

Park, S; Burrows, D N; Slane, P O; Nousek, J A; Garmire, G P; Park, Sangwook; Hughes, John P.; Burrows, David N.; Slane, Patrick O.; Nousek, John A.; Garmire, Gordon P.

2003-01-01

372

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

373

A Broadband X-Ray Study of the Supernova Remnant 3C 397  

CERN Multimedia

We present an X-ray study of the radio bright supernova remnant (SNR) 3C 397 with ROSAT, ASCA, and RXTE. A central X-ray spot seen with the ROSAT High-Resolution Imager hints at the presence of a pulsar-powered component, and gives this SNR a composite X-ray morphology. Combined ROSAT and ASCA imaging show that the remnant is highly asymmetric, with its hard X-ray emission peaking at the western lobe. The spectrum of 3C 397 is heavily absorbed, and dominated by thermal emission with emission lines evident from Mg, Si, S, Ar and Fe. Single-component models fail to describe the spectrum, and at least two components are required. We use a set of non-equilibrium ionization (NEI) models (Borkowski et al. in preparation). The temperatures from the soft and hard components are 0.2 keV and 1.6 keV respectively. The corresponding ionization time-scales $n_0 t$ ($n_0$ being the pre-shock hydrogen density) are 6 $\\times 10^{12}$ cm$^{-3}$ s and 6 $\\times$ 10$^{10}$ cm$^{-3}$ s, respectively. The spectrum obtained with t...

Safi-Harb, S; Arnaud, K A; Keohane, J W; Borkowski, K J; Dyer, K K; Reynolds, S P; Hughes, J P

2000-01-01

374

Unveiling the spatial structure of the overionized plasma in the supernova remnant W49B  

CERN Multimedia

W49B is a mixed-morphology supernova remnant with thermal X-ray emission dominated by the ejecta. In this remnant, the presence of overionized plasma has been directly established, with information about its spatial structure. However, the physical origin of the overionized plasma in W49B has not yet been understood. We investigate this intriguing issue through a 2D hydrodynamic model that takes into account, for the first time, the mixing of ejecta with the inhomogeneous circumstellar and interstellar medium, the thermal conduction, the radiative losses from optically thin plasma, and the deviations from equilibrium of ionization induced by plasma dynamics. The model was set up on the basis of the observational results. We found that the thermal conduction plays an important role in the evolution of W49B, in- ducing the evaporation of the circumstellar ring-like cloud (whose presence has been deduced from previous observations) that mingles with the surrounding hot medium, cooling down the shocked plasma, an...

Zhou, Xin; Bocchino, Fabrizio; Orlando, Salvatore; Chen, Yang

2011-01-01

375

Theory of cosmic ray production in the supernova remnant RX J1713.7-3946  

CERN Document Server

A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) is employed to investigate the properties of SNR RX J1713.7-3946. Observations of the nonthermal radio and X-ray emission spectra as well as the H.E.S.S. measurements of the very high energy gamma-ray emission are used to constrain the astronomical and the particle acceleration parameters of the system. Under the assumptions that RX J1713.7-3946 was a core collapse supernova (SN) of type II/Ib with a massive progenitor, has an age of \\approx 1600 yr and is at a distance of \\approx 1 kpc, the theory gives indeed a consistent description for all the existing observational data. Specifically it is shown that an efficient production of nuclear CRs, leading to strong shock modification, and a large downstream magnetic field strength B_d ~ 100 mkG can reproduce in detail the observed synchrotron emission from radio to X-ray frequencies together with the gamma-ray spectral characteristics as observed by the H.E.S.S. telescopes. S...

Berezhko, E G

2006-01-01

376

X-ray emission from supernova remnants near gamma-ray sources  

International Nuclear Information System (INIS)

The imaging proportional counter of the Einstein Observatory has been used to search for X-ray emission from eight radio supernova remnants which are near three of the Cos-B unidentified ?-ray sources; 2CG 311--01, CG 327--0, and CG 333+0. We observe emission from three of the remnants and upper limits on the remainder which are consistent with the luminosity expected from a simple blast-wave-heated plasma model of the process. Thus none of the remnants are superluminous as might be expected if they follow the pattern of the Crab Nebula. One of the remnants, RCW 103, may be Vela-like in that Tuohy and Garmire have recently reported a weak point source approximately centrally located which may be associated with a rotating neutron star remnant of the supernova explosion and which therefore may be associated with CG 333+0

1981-02-15

377

The kinematics of the bi-lobal supernova remnant G 65.3+5.7 - Paper II  

CERN Document Server

Further deep, narrow-band images in the light of [O III] 5007 A have been added to the previous mosaic of the faint galactic supernova remnant G 65.3+5.7. Additionally longslit spatially resolved [O III] 5007 A line profiles have been obtained at sample positions using the Manchester Echelle Spectrometer at the San Pedro Martir observatory. The remnant is shown to be predominantly bi-lobal with an EW axis for this structure. However, a faint additional northern lobe has now been revealed. Splitting of the profiles along the slit lengths, when extrapolated to the remnant's centre, although uncertain suggests that the expansion velocity of this remnant is between 124 and 187 km/s ie much lower than the 400 km/s previously predicted for the forward shock velocity from the X-ray emission. An expansion proper motion measurement of 2.1+-0.4 arcsec in 48 years for the remnant's filamentary edge in the light of Halpha+[N II] has also been made. When combined with an expansion velocity of ~155 km/s, a distance of ~800...

Bournis, P; López, J A; Mavromatakis, F; Redman, M P; Harman, D J; Goudis, C D

2004-01-01

378

GSH 90-28-17: a possible old supernova remnant  

Science.gov (United States)

GSH 90-28-17 is a high-latitude Galactic H I supershell, identified in the H I supershell catalogues with a velocity vlsr ˜ -17 km s-1. We used the new Galactic Arecibo L-band Feed Array (GALFA) H I survey data, which have much higher resolution and sensitivity than was previously available, to re-examine the properties of the supershell. We derived a new distance of 400 pc for GSH 90-28-17 and suggested that it is related to the Lac OB1 association. The radius of GSH 90-28-17 is 66.0 ± 3.5 pc. The H I mass of the shell is (3.1 ± 0.1) × 104 M?. It has an age of ˜4.5 Myr and a total kinetic energy of (8.2 ± 0.3) × 1048 erg. We extracted radio continuum data for the GSH 90-28-17 region from the 408-MHz All-Sky Survey and Bonn 1420-MHz survey and filtered the diffuse background Galactic emission. A radio loop-like ridge is found to be associated with the H I shell at both frequencies and shows a non-thermal origin, with a temperature-temperature (TT)-plot index of ? = -1.35 ± 0.69. In addition, the pulsar J2307+2225, with a similar distance, is found in the shell region. We conclude that GSH 90-28-17 is probably an old, type II supernova remnant in the solar neighbourhood.

Xiao, L.; Zhu, M.

2014-02-01

379

Numerical Simulations of Dust Destruction in Supernova Reverse Shocks  

CERN Document Server

We investigate through hydrodynamic simulations the destruction of newly-formed dust grains by sputtering in the reverse shocks of supernova remnants. Using an idealized setup of a planar shock impacting a dense, spherical clump, we implant a population of Lagrangian particles into the clump to represent a distribution of dust grains in size and composition. We then post-process the simulation output to calculate the grain sputtering for a variety of species and size distributions. We explore the parameter space appropriate for this problem by altering the over-density of the ejecta clumps and the speed of the reverse shocks. Since radiative cooling could lower the temperature of the medium in which the dust is embedded and potentially protect the dust by slowing or halting grain sputtering, we study the effects of different cooling methods over the time scale of the simulations. In general, our results indicate that grains with radii less than 0.1 microns are sputtered to much smaller radii and often destroy...

Silvia, D W; Shull, J M

2010-01-01

380

Gamma-ray sources, supernova remnants, OB associations, and the origin of cosmic rays  

International Nuclear Information System (INIS)

Although supernova explosions are widely thought to give rise to cosmic rays (nucleons), there is, as yet, no direct evidence from individual objects to support this view. A possible tool in this respect is the detection of ?-rays emitted by supernova remnants (SNRs) via ?0 decay. However, the accumulating ?-ray data show that SNRs as a class are not ?-ray sources, but rather that ?-ray sources are, in general, closely linked with young objects. We examine, among other possibilities, whether a restricted class of SNRs are actually ?-ray sources; we restrict the class to those SNRs physically linked with extreme Population I objects. Spatial coincidences between SNRs and OB associations or H II regions (SNOBs) are sought by various methods, and this yields a list of about 30 objects (which is certainly incomplete). From the Cos B data, one finds that five (perhaps six) out of 11 as yet unidentified ?-ray sources (above 100 MeV) are associated with SNOBs, and there is a hint that as much as three-fourths of the best identified SNOBs are seen in ?-rays. The associated probabilities of chance coincidence are approx.10-4. Angular and other statistical considerations also support this association. Pending confirmation, if a substantial proportion of the observed ?-rays does come from ?0 decay, SNOBs appear to be a major source of galactic cosmic rays, in which cosmic-ray (> or =2 GeV) energy densities in the range approx.10--100 times the solar neighborhood value are found. A phenomenological scenario is suggested. Cosmic rays are produced by a two-step process, in which low-energy (MeV range) particles are injected by young stars pertaining to an OB association, and are subsequently accelerated by the shock wave of a neighboring supernova explosion. Isolated SNRs, possible links with light-element production, and the links between SNOBS and other astronomical objects are discussed

1979-07-01

 
 
 
 
381

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

382

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

383

Dust Formation in the young core-collapse supernova remnant E0102  

CERN Multimedia

We present Spitzer IRS and IRAC observations of the young supernova remnant E0102 (SNR 1E0102.2-7219) in the Small Magellanic Cloud. The infrared spectra show strong ejecta lines of Ne and O, with the [Ne II] line at 12.8 microns having a large velocity dispersion of 2,000-4,500 km/s indicative of fast-moving ejecta. Unlike the young Galactic SNR Cas A, E0102 lacks emission from Ar and Fe. Diagnostics of the observed [Ne III] line pairs imply that [Ne III] emitting ejecta have a low temperature of 650 K, while [Ne V] line pairs imply that the infrared [Ne V] emitting ejecta have a high density of ~10^4/cm3. We have calculated radiative shock models for various velocity ranges including the effects of photoionization. The shock model indicates that the [Ne V] lines come mainly from the cooling zone, which is hot and dense, whereas [Ne II] and [Ne III] come mainly from the photoinization zone, which has a low temperature of 400-1000 K. We estimate an infrared emitting Ne ejecta mass of 0.04 Msun from the infrar...

Rho, J; Tappe, A; Hwang, U; Slavin, J D; Kozasa, T; Dunne, L

2009-01-01

384

Nonuniform Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3  

CERN Document Server

We report measurements of X-ray expansion of the youngest Galactic supernova remnant (SNR), G1.9+0.3, using Chandra observations in 2007, 2009, and 2011. The measured rates strongly deviate from uniform expansion, decreasing radially by about 60% along the X-ray bright SE-NW axis from 0."84% +/- 0."06% per yr to 0."52% +/- 0."03% per yr. This corresponds to undecelerated ages of 120-190 yr, confirming the young age of G1.9+0.3, and implying a significant deceleration of the blast wave. The spatially-integrated dominantly synchrotron X-ray flux increases at 1.9% +/- 0.4% per yr. We identify the outer and inner rims with the blast wave and reverse shock, respectively. Sudden large density gradients in either ejecta or ambient medium are required to produce the sudden deceleration of the reverse shock or the blast wave implied by the large spread in expansion ages. The blast wave could have been decelerated recently by an encounter with a modest density discontinuity in the ambient medium, such as found at a win...

Borkowski, K J; Green, D A; Hwang, U; Petre, R; Krishnamurthy, K; Willett, R

2014-01-01

385

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

386

Optical observations of the supernova remnant G 69.4+1.2  

CERN Document Server

We performed deep optical observations of the area of the new supernova remnant G 69.4+1.2 in the emission lines of [O III], Halpha+[N II] and [S II]. The low ionization images reveal diffuse and filamentary emission in the central and south, south-west areas of our field. Estimates of the [S II]/Halpha ratio suggest that the detected emission in these areas originates from shock heated gas, while the strong extended source in the north must be an HII region. The medium ionization image of [O III] shows a single filament close to the field center. Emission from [O III] is not detected elsewhere in the field but only in the north from LBN 069.96+01.35. Deep long-slit spectra taken at the position of the [O III] filament suggest shock velocities ~120 km/s, while in other areas velocities around 50 km/s are expected. The sulfur lines ratio indicates electron densities less than 120 cm^{-3}. The absolute Halpha flux is ~5 x 10^{-17} erg s^{-1} cm^{-2} arcsec^{-2}. The optical emission is very well correlated with...

Mavromatakis, F; Paleologou, E V; Mavromatakis, Fotis; Boumis, Panayotis; Paleologou, Euthimios V.

2002-01-01

387

THE FERMI BUBBLES AS A SCALED-UP VERSION OF SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

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

2013-09-20

388

THE FERMI BUBBLES AS A SCALED-UP VERSION OF SUPERNOVA REMNANTS  

Energy Technology Data Exchange (ETDEWEB)

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 [Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Ohira, Yutaka; Yamazaki, Ryo, E-mail: fujita@vega.ess.sci.osaka-u.ac.jp [Department of Physics and Mathematics, Aoyama Gakuin University, Fuchinobe, Chuou-ku, Sagamihara 252-5258 (Japan)

2013-09-20

389

The many sides of RCW 86: a type Ia supernova remnant evolving in its progenitor's wind bubble  

CERN Document Server

We present the results of a detailed investigation of the Galactic supernova remnant RCW 86 using the XMM-Newton X-ray telescope. RCW 86 is the probable remnant of SN 185 A.D, a supernova that likely exploded inside a wind-blown cavity. We use the XMM-Newton Reflection Grating Spectrometer (RGS) to derive precise temperatures and ionization ages of the plasma, which are an indication of the interaction history of the remnant with the presumed cavity. We find that the spectra are well fitted by two non-equilibrium ionization models, which enables us to constrain the properties of the ejecta and interstellar matter plasma. Furthermore, we performed a principal component analysis on EPIC MOS and pn data to find regions with particular spectral properties. We present evidence that the shocked ejecta, emitting Fe-K and Si line emission, are confined to a shell of approximately 2 pc width with an oblate spheroidal morphology. Using detailed hydrodynamical simulations, we show that general dynamical and emission pro...

Broersen, Sjors; Vink, Jacco; Bamba, Aya

2014-01-01

390

Neutral hydrogen in the vicinity of galactic radio sources. W28 supernova remnant  

International Nuclear Information System (INIS)

The results of emission and absorption observations of H I in the vicinity of the radio source W 28 made with the radio telescope RATAN-600 with a resolution of 2.4'x45'x6.3 km/s are presented. The distance to the supernova remnant is estimated using the H I absorption line ( approximately equal to 3 kpc) and it is shown that its compact H II regions are at the same distance. The expanding H I envelope is found in emission around W 28 which has a diameter of 82 pc, mass 6.9x10"4 solar mass and the expansion velocity of 20 km/s. The parameters of the supernova remnant are derived (age 5.8x10"5 years, initial energy 8.4x10"5"1 ergs) and some conclusions on a possible genetic connection between H II regions and the supernova remnant are made

1982-01-01

391

RX-J0852?4622: THE NEAREST HISTORICAL SUPERNOVA REMNANT – AGAIN  

Directory of Open Access Journals (Sweden)

Full Text Available RX-J0852?4622, a supernova remnant, is demonstrated to be closer than 500 pc, based on the measurements of the angular radius, the angular expansion rate and the TeV g-ray flux. This is a new method of limiting the distance to any supernova remnant with hadronic induced TeV g-ray flux. The progenitor star of RX-J0852?4622 probably exploded in its blue supergiant wind, like SN 1987A, preceeded by a red supergiant phase. A cool dense shell, expected around the outskirts of the red wind, my have been identified. The distance (200 pc and age (680 yr of the supernova remnant, originally proposed, are supported.

Bernd Aschenbach

2013-12-01

392

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

393

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

394

Giant X-ray source in Cygnus is a peculiar supernova remnant  

International Nuclear Information System (INIS)

The analytic solution for the evolution of supernova remnants on the radiative phase is obtained. It is shown that the X-ray source Cygnus Superbubble might be formed by an explosion with the energy release of 10_5-10_5_3 ergs. The analysis of the light curve of SN 1961 v shows that this supernova is the result of an explosion with an energy of about 2x10_5_2 ergs of a supermassive star with the mass of about 10_3 solar masses. An evolutionary sequence for the formation of giant shell sources is suggested: presupernova - an object of the type R 136a, supernova - an explosion of the type SN 1961v, supernova remnant - aource of the type Cygnus Superbubble

1982-11-01

395

Supernova remnants and diffuse ionized gas in M31  

Science.gov (United States)

Researchers have compiled an initial list of radio/optical supernova remnants (SNRs) in M31, by searching for radio identifications of emission-line sources with a high (SII)/H alpha ratio (greater than 0.60). The (SII) filter included both sulfur lines and the H alpha filter did not include (NII). This search revealed 11 SNRs, of which only two were known. In addition, researchers detected radio emission from 3 SNRs that were identified in previous optical surveys (D'Odorico et al., 1980), but that were outside the charge coupled device (CCD) fields. The 14 objects only include the most obvious candidates, but a full search is in progress and the researchers expect to find several more SNRs. Also not all optical SNRs show detectable radio emission and a pure optical list of SNR candidates based only on the ratio of (SII)/H alpha emission contains many more objects. Two conclusions are apparent. First, the radio properties of the SNRs in M31 are quite similar to those of Galactic SNRs as is illustrated. The brightnesses are not systematically lower as has been suggested in the past (Dickel and D'Odorico, 1984). Second, the slope of the relation is close to -2; this slope is expected from the intrinsic dependence between surface brightness and diameter. The radio luminosity of the SNRs does not seem to depend strongly on diameter, or age, contrary to model predictions. Selection effects, however, play an important role in these plots. The CCD images show widespread diffuse ionized gas with a ratio of (SII)/H alpha that is higher than that of discrete HII regions. Discrete HII regions typically show ratios between 0.2 to 0.3, while the diffuse gas in the arms consistently shows ratios of 0.5. Researchers can trace this gas across the spiral arms to emission measures below 5 pc cm (-6). Its properties seem to be similar to that of the diffuse gas in the solar neighborhood.

Walterbos, Rene; Braun, Robert

1990-01-01

396

XMM-NEWTON OBSERVATIONS OF TWO CANDIDATE SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

Candidate supernova remnants (SNRs) G23.5+0.1 and G25.5+0.0 were observed by XMM-Newton in the course of a snapshot 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 (J1833-0827; P = 85.3 ms, ? = 147 kyr, E-dot = 5.8 × 1035 erg s–1, d = 5.7 kpc), with the PWN luminosity L0.2-10keV ? 5 × 1033 erg s–1 ? 8 × 10–3 E-dot . The pulsar is not resolved in the EPIC images. 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. The field also contains SGR 1833-0832 and another middle-aged pulsar B1829-08 (J1832-0827; P = 647 ms, ? = 161 kyr, E-dot = 9.3 × 1033 erg s–1, d = 4.7 kpc), none of which are detected in our observation. 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 (P = 70.5 ms, ? = 23 kyr, E-dot = 5.5 × 1036 erg s–1) embedded in a PWN with extent of 1.'3. The unabsorbed pulsar + PWN luminosity is L2-11keV ? 2 × 1034 erg s–1 ? 4 × 10–3 E-dot at an assumed distance of 7 kpc. We also detected another PWN candidate (AX J1837.3-0652) with an extent of 2' and unabsorbed luminosity L2-10keV ? 4 × 1033 erg s–1 at d = 7 kpc. The third X-ray source, located within the extent of the HESS J1837-069, has a peculiar extended radio counterpart, possibly a radio galaxy with a double nucleus or a microquasar. We did not find any evidence of the SNR emission in the G25.5+0.0 field. We provide detailed multiwavelength analysis and identifications of other field sources and discuss robustness of the G25.5+0.0 and G23.5+0.1 classifications as SNRs.

2012-01-20

397

Observation of Extended VHE Emission from the Supernova Remnant IC 443 with VERITAS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present evidence that the very-high-energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best-studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127, both of which are important targets for VHE observations. VERITAS observed IC 443 for 37.9 hours during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a si...

Veritas, Collaboration; Acciari, V. A.; Aliu, E.; Arlen, T.; Aune, T.; Bautista, M.; Beilicke, M.; Benbow, W.; Bradbury, S. M.; Buckley, J. H.; Bugaev, V.; Butt, Y.; Byrum, K.; Cannon, A.; Celik, O.

2009-01-01

398

Fermi LAT gamma-ray observations of the supernova remnant HB21  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the analysis of Fermi Large Area Telescope (LAT) {\\gamma}-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{\\deg}x1{\\deg}.5, compared to the LAT 68% containme...

Pivato, G.; Hewitt, J. W.; Collaboration, L. Tibaldo For The Fermi Lat

2013-01-01

399

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

400

Spherically symmetric relativistic MHD simulations of pulsar wind nebulae in supernova remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Pulsars, formed during supernova explosions, are known to be sources of relativistic magnetized winds whose interaction with the expanding supernova remnants (SNRs) gives rise to a pulsar wind nebula (PWN). We present spherically symmetric relativistic magnetohydrodynamics (RMHD) simulations of the interaction of a pulsar wind with the surrounding SNR, both in particle and magnetically dominated regimes. As shown by previous simulations, the evolution can be divided in three...

Bucciantini, N.; Blondin, J. M.; Del Zanna, L.; Amato, E.

2003-01-01

 
 
 
 
401

TeV Neutrinos from SuperNova Remnants embedded in Giant Molecular Clouds  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The recent detection of $\\gamma$-rays with energy up to 10 TeV from dense regions surrounding some Supernova Remnants (SNR) provides strong, though still not conclusive, evidence that the nucleonic component of galactic Cosmic Rays is accelerated in the supernova outflows. Neutrino telescopes could further support the validity of such scenario by detecting neutrinos coming from the same regions. We re-evaluate the TeV range neutrino-photon flux ratio to be expected from pion...

Cavasinni, Vincenzo; Grasso, Dario; Maccione, Luca

2006-01-01

402

Monochromatic photography of the Cygnus Loop supernova remnant. Plotting of isophotes of partial nebula radiation in the [OIII] and [NII]+H? lines  

International Nuclear Information System (INIS)

System of the isophotes of the 9' size in the west part of the Cyg Loop supernova remnant using monochromatic photographs in the [O3] and [N2]+Hsub(?) lines is obtained. A relative displacement of the regions of emission in these lines is discovered and explained by temperature reduction due to radiative losses behind the shock wave of the supernova explosion. The morphology difference between the [O3] and [N2]+Hsub(?) lxnes is explained. Anomalously large intensity ratios Isub([O3])/Isub(Hsub(?)) are supposed to be due to spatial separation of the corresponding emission regions

1982-11-01

403

Ejecta detection in the middle-aged Galactic supernova remnant G296.1-0.5 observed with Suzaku  

CERN Multimedia

In this paper, we report the detection of ejecta in the middle-aged Galactic supernova remnant G296.1-0.5 with the X-ray Imaging Spectrometer onboard the Suzaku satellite. The spectra of three lobes, north, southeast and southwest and inter-lobe regions, consist of soft (0.3-2.0 keV) emission originated from non-equilibrium ionization plasma. In north, southeast and inter-lobe regions, the thermal emission can be represented by a one-component, in southwest region it can be represented by two- component non-equilibrium ionization (VNEI) model. The spectra of studied regions have lines of N, O, Ne, Mg and Si elements. Si emission from this remnant is shown for the first time in this work. Enhanced abundances of Ne, Mg and Si elements obtained show the ejecta contribution in all regions. Assuming that the remnant is in Sedov phase, we obtained ambient density n0 ~ 0.45 cm-3, age t ~ 2.8 x 104 yr, shock velocity Vs ~ 320 km s-1, shock temperature Ts ~ 1.2 x 106 K, and swept-up mass Msw ~ 340 M at an adopted dist...

Gok, F

2011-01-01

404

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

405

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

406

X-Ray Kinematics of the Galactic Core-Collapse Supernova Remnant G292.0+1.8  

Science.gov (United States)

We report on the results from the preliminary analysis of our 120 ks Chandra HETGS observation of the Galactic core-collapse supernova remnant (SNR) G292.0+1.8. To probe the 3D distribution of the metal-rich ejecta features, we measured Doppler shifts in emission lines from ejecta knots projected at a range of distances from the SNR center using high resolution HETGS spectroscopy. We estimate radial velocities of v ~ -2200 - +1300 km/s. Their overall distribution in the velocity-position space suggests an expanding shell of ejecta. We qualitatively estimate the locations of the reverse shock and contact discontinuity based on this distribution. The reverse shock in G292.0+1.8 appears to be at ~130" from the SNR center, which is close to the outer boundary of the radio pulsar wind nebula.

Park, Sangwook; Bhalerao, J.; Dewey, D.; Hughes, J. P.; Slane, P. O.; Burrows, D. N.; Lee, J.; Mori, K.

2014-01-01

407

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

CERN Document Server

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

408

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

409