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1

Resonance Line Scattering in Supernova Remnant Shocks  

CERN Document Server

We present a three dimensional radiative transfer model to examine the effects of resonance line scattering in the post-shock flow behind a non-radiative supernova remnant shock. For a rippled shock front viewed edge-on, line scattering significantly reduces the observed flux of CIV 1549 and NV 1240, two important diagnostic lines in the ultraviolet spectra of supernova remnants. The correction factor (defined to be the ratio of the line flux that would be observed neglecting scattering, to the actual observed line flux) is a function of position within the filament. For sufficiently large regions that include crisp edges as well as more diffuse regions of the filament structure, the CIV and NV correction factors are between about 1.5 and 3.5 (and the CIV correction factor is invariably larger than the NV correction factor). The correction factors have a larger range when smaller regions are considered. The CIV correction factor is about 6 at the filament edges, while the NV correction factor is about 4. Thes...

Sankrit, R; Sankrit, Ravi; Wood, Kenneth

2001-01-01

2

Particle Acceleration by Shocks in Supernova Remnants  

Science.gov (United States)

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 exaelectronvolt (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 cosmic ray (CR) spectrum up to the knee at a few petaelectronvolt (PeV). The answer depends in large part on the detailed physics of diffusive shock acceleration.

Bell, Anthony Raymond

2014-10-01

3

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

4

Supernova remnants  

International Nuclear Information System (INIS)

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

5

Supernova remnants  

International Nuclear Information System (INIS)

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

6

Electrostatic Potentials in Supernova Remnant Shocks  

CERN Document Server

Recent advances in the understanding of the properties of supernova remnant shocks have been precipitated by the Chandra and XMM X-ray Observatories, and the HESS Atmospheric Cerenkov Telescope in the TeV band. A critical problem for this field is the understanding of the relative degree of dissipative heating/energization of electrons and ions in the shock layer. This impacts the interpretation of X-ray observations, and moreover influences the efficiency of injection into the acceleration process, which in turn feeds back into the thermal shock layer energetics and dynamics. This paper outlines the first stages of our exploration of the role of charge separation potentials in non-relativistic electron-ion shocks where the inertial gyro-scales are widely disparate, using results from a Monte Carlo simulation. Charge density spatial profiles were obtained in the linear regime, sampling the inertial scales for both ions and electrons, for different magnetic field obliquities. These were readily integrated to a...

Baring, M G; Baring, Matthew G.; Summerlin, Errol J.

2006-01-01

7

New insights on hadron acceleration at supernova remnant shocks  

CERN Document Server

We outline the main features of nuclei acceleration at supernova remnant forward shocks, stressing the crucial role played by self-amplified magnetic fields in determining the energy spectrum observed in this class of sources. In particular, we show how the standard predictions of the non-linear theory of diffusive shock acceleration has to be completed with an additional ingredient, which we propose to be the enhanced velocity of the magnetic irregularities particles scatter against, to reconcile the theory of efficient particle acceleration with recent observations of gamma-ray bright supernova remnants.

Caprioli, Damiano

2013-01-01

8

A mechanism for strong shock electron heating in supernova remnants  

Science.gov (United States)

It is shown that collisionless shock waves propagating away from a supernova may be directly responsible for the 10 keV X-ray emission seen in supernova remnants. A sequence of plasma instabilities (Buneman and ion acoustic) between the reflected and/or transmitted ions and the background electrons at the foot of the shock front can give rise to rapid anomalous heating of electrons. Hybrid simulations of a perpendicular collisionless shock are presented to demonstrate that this heating can arise within a self-consistently computed shock structure.

Cargill, P. J.; Papadopoulos, K.

1988-01-01

9

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

10

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

11

Cosmic Ray Acceleration at Perpendicular Shocks in Supernova Remnants  

Science.gov (United States)

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 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 ?), but becomes independent of the particle momentum at high momenta (reaching a constant value ?? above some characteristic momentum p 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 distribution that can be obtained when the particle pressure back-reacts on the flow. We observe that for a given index ? and injection level, the shock modifications are similar for different possible values of p c, whereas the particle spectra differ markedly. Of particular interest, low values of p c tend to remove the concavity once thought to be typical of non-linear DSA, and result in steep spectra, as required by recent high-energy observations of Galactic SNRs.

Ferrand, Gilles; Danos, Rebecca J.; Shalchi, Andreas; Safi-Harb, Samar; Edmon, Paul; Mendygral, Peter

2014-09-01

12

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

CERN Document Server

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

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

2008-01-01

13

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

CERN Document Server

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 occuring 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 devel...

Lee, Shiu-Hang; Ellison, Donald C

2008-01-01

14

H2 excitation by magnetic shock precursors in the Cygnus Loop supernova remnant  

International Nuclear Information System (INIS)

Emission from vibrationally excited H2 has been discovered which is associated with the bright optical shock-excited filaments to the northeast of the Cygnus Loop supernova remnant. Infrared spectroscopy and infrared and optical narrow-band images of the shock-excited gas have been obtained in an effort to understand the mechanism of H2 excitation. A shock model with a magnetic precursor is proposed which explains quantitatively the observed H2 surface brightness, level population, and relation to optical emission. A shock with a magnetic precursor can also account for some of the anomalous properties of nonradiative shocks. 64 refs

15

An Integral View of Balmer-dominated Shocks in Supernova Remnants  

CERN Document Server

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

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

2013-01-01

16

APEX observations of supernova remnants - I. Non-stationary MHD-shocks in W44  

CERN Document Server

Aims. The interaction of supernova remnants (SNRs) with molecular clouds gives rise to strong molecular emission in the far-IR and sub-mm wavelength regimes. The application of MHD shock models in the interpretation of this line emission can yield valuable information on the energetic and chemical impact of supernova remnants. Methods. New mapping observations with the APEX telescope in CO (3-2), (4-3), (6-5), (7-6) and 13CO (3-2) towards two regions in the supernova remnant W44 are presented. Integrated intensities are extracted on five different positions, corresponding to local maxima of CO emission. The integrated intensities are compared to the outputs of a grid of models, which combine an MHD shock code with a radiative transfer module based on the large velocity gradient approximation. Results. All extracted spectra show ambient and line-of-sight components as well as blue- and red-shifted wings indicating the presence of shocked gas. Basing the shock model fits only on the highest-lying transitions th...

Anderl, S; Güsten, R

2014-01-01

17

The Role of Diffusive Shock Acceleration on Non-Equilibrium Ionization in Supernova Remnants  

CERN Document Server

We present results of semi-analytic calculations which show clear evidence for changes in the non-equilibrium ionization behind a supernova remnant forward shock undergoing efficient diffusive shock acceleration (DSA). The efficient acceleration of particles (i.e., cosmic rays) lowers the shock temperature and raises the density of the shocked gas, thus altering the ionization state of the plasma in comparison to the test particle approximation where cosmic rays gain an insignificant fraction of the shock energy. The differences between the test particle and efficient acceleration cases are substantial and occur for both slow and fast temperature equilibration rates: in cases of higher acceleration efficiency, particular ion states are more populated at lower electron temperatures. We also present results which show that, in the efficient shock acceleration case, higher ionization fractions are reached noticeably closer to the shock front than in the test-particle case, clearly indicating that DSA may enhance...

Patnaude, Daniel J; Slane, Patrick

2009-01-01

18

Galactic Cosmic Rays from Supernova Remnants: II Shock Acceleration of Gas and Dust  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Ellison, Donald C.; Drury, L. O. C.; Meyer, Jean-paul

1997-01-01

19

Electron-Ion Heat Exchange from Electrostatic Potentials in Supernova Remnant Shocks  

Science.gov (United States)

The partitioning of thermal energy between electrons and ions in supernova remnant shocks is an outstanding problem. X-ray observations show that inferred proton temperatures differ considerably from simple hydrodynamic expectations of shock heating in the compressed flow. In electron-ion shocks, a cross-shock electrostatic potential, akin to a capacitance, should arise due to the different inertial gyroscales of the two species. It provides a mechanism for energy exchange between these charges. In this paper, we explore the effects of cross-shock electrostatics using a Monte Carlo simulation, where test particles gyrate and stochastically diffuse in a background fluid pre-defined by MHD jump conditions. The cross-shock electric field is derived from the steady-state spatial distribution of particles via a modified Poisson's equation that includes Debye screening. In subsequent simulation runs, the charges kinetically respond to this field, in addition to the background magnetic and drift electric fields, and new charge separation potentials are derived. This iterative feedback loop continues until a self-consistent solution is obtained. Our results show a significant departure of the electron distribution from the usual thermal plus power-law form, and clearly demonstrates substantial heating of the electron population. This phenomenon has important implications for the interpretation of X-ray emission in supernova remnants.

Baring, Matthew; Barchas, Joseph

20

Bipolar supernova remnants and the obliquity dependence of shock acceleration  

Science.gov (United States)

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.

Fulbright, Michael S.; Reynolds, Stephen P.

1990-07-01

 
 
 
 
21

PLASMA INSTABILITIES AS A RESULT OF CHARGE EXCHANGE IN THE DOWNSTREAM REGION OF SUPERNOVA REMNANT SHOCKS  

International Nuclear Information System (INIS)

H? emission from supernova remnants (SNRs) implies the existence of neutral hydrogen in the circumstellar medium. Some of the neutral particles penetrating the shock are ionized by the charge-exchange process and make a cold ion beam in the shock downstream region. We perform linear analyses of collisionless plasma instabilities between the cold beam and the hot downstream plasma. We find that, under typical SNR conditions, either the resonant instability or the Weibel instability is the most unstable. This mechanism may amplify the magnetic field to more than 100 ?G and changes the shock structure. As a result, the radio spectrum and the large magnetic field can be explained, apart from the widely discussed Bell's mechanism.

22

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

23

APEX observations of supernova remnants. I. Non-stationary magnetohydrodynamic shocks in W44  

Science.gov (United States)

Context. When supernova blast waves interact with nearby molecular clouds, they send slower shocks into these clouds. The resulting interaction regions provide excellent environments for the use of MHD shock models to constrain the physical and chemical conditions in these regions. Aims: The interaction of supernova remnants (SNRs) with molecular clouds gives rise to strong molecular emission in the far-IR and sub-mm wavelength regimes. The application of MHD shock models in the interpretation of this line emission can yield valuable information on the energetic and chemical impact of SNRs. Methods: New mapping observations with the APEX telescope in 12CO (3-2), (4-3), (6-5), (7-6), and 13CO (3-2) towards two regions in the SNR W44 are presented. Integrated intensities are extracted on five different positions, corresponding to local maxima of CO emission. The integrated intensities are compared to the outputs of a grid of models, which combine an MHD shock code with a radiative transfer module based on the large velocity gradient approximation. Results: All extracted spectra show ambient and line-of-sight components as well as blue- and red-shifted wings indicating the presence of shocked gas. Basing the shock model fits only on the highest-lying transitions that unambiguously trace the shock-heated gas, we find that the observed CO line emission is compatible with non-stationary shocks and a pre-shock density of 104 cm-3. The ages of the modelled shocks scatter between values of ~1000 and ~3000 years. The shock velocities in W44F are found to lie between 20 km s-1 and 25 km s-1, while in W44E fast shocks (30-35 km s-1) as well as slower shocks (~20 km s-1) are compatible with the observed spectral line energy diagrams. The pre-shock magnetic field strength components perpendicular to the line of sight in both regions have values between 100 ?G and 200 ?G. Our best-fitting models allow us to predict the full ladder of CO transitions, the shocked gas mass in one beam as well as the momentum and energy injection. The velocity-integrated CO maps shown in Figs. 3 and 4 are available as FITS files at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/569/A81Appendix A is available in electronic form at http://www.aanda.org

Anderl, S.; Gusdorf, A.; Güsten, R.

2014-09-01

24

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

25

Time-dependent Diffusive Shock Acceleration in Slow Supernova Remnant Shocks  

CERN Document Server

Recent gamma ray observations show that middle aged supernova remnants interacting with molecular clouds can be sources of both GeV and TeV emission. Models involving re-acceleration of pre-existing cosmic rays in the ambient medium and direct interaction between supernova remnant and molecular clouds have been proposed to explain the observed gamma ray emission. For the re-acceleration process, standard DSA theory in the test particle limit produces a steady state particle spectrum that is too flat compared to observations, which suggests that the high energy part of the observed spectrum has not yet reached a steady state. We derive a time dependent DSA solution in the test particle limit for situations involving re-acceleration of pre-existing cosmic rays in the preshock medium. Simple estimates with our time dependent DSA solution plus a molecular cloud interaction model can reproduce the overall shape of the spectra of IC 443 and W44 from GeV to TeV energies through pure $\\pi^0$-decay emission. We allow ...

Tang, Xiaping

2014-01-01

26

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

Science.gov (United States)

We present results of 3-D Particle-In-Cell simulations of magnetic turbulence production by cosmic-rays drifting upstream of supernova remnant shocks. The studies aim at testing the predictions of a strong amplification of short-wavelength nonresonant wave modes and at studying the subsequent evolution of the magnetic turbulence and its backreaction on cosmic ray trajectories. We confirm the generation of the turbulent magnetic field due to the drift of cosmic-ray ions in the upstream plasma, but show that an oblique filamentary mode grows more rapidly than the nonresonant parallel modes found in analytical theory. The growth rate of the field perturbations is slower than estimated for nonresonant modes using the quasilinear approach, and the amplitude of the turbulence saturates at about ?B/B˜1.

Pohl, Martin; Niemiec, Jacek; Stroman, Tom

2008-04-01

27

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

28

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

Science.gov (United States)

We present new models for the forward and reverse shock thermal X-ray emission from core-collapse and Type Ia supernova remnants (SNRs) that include the efficient production of cosmic rays (CR) via nonlinear diffusive shock acceleration (DSA). Our CR-hydro-NEI code takes into account non-equilibrium ionization, 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 that 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 emission from young SNRs is a powerful tool for determining specific SN elemental contributions and for providing critical information that helps to understand the type and energetics of the explosion, the composition of the ambient medium in which the SN exploded, and the ionization and dynamics of the hot plasma in the shocked SN ejecta and interstellar medium. With the approaching launch of the next-generation X-ray satellite Astro-H, observations of spectral lines with unprecedented high resolution will become a reality. Our self-consistent calculations of the X-ray spectra from various progenitors will help interpret future observations of SNRs.

Lee, Shiu-Hang; Patnaude, Daniel J.; Ellison, Donald C.; Nagataki, Shigehiro; Slane, Patrick O.

2014-08-01

29

Shocked Molecular Gas in the Supernova Remnants W 28 and W 44: Near-infrared and millimeter-wave observations  

CERN Document Server

High resolution millimeter-wave and near-infrared observations of the supernova remnants W28 and W44 reveal extensive shocked molecular gas where supernova blast waves are propagating into giant molecular clouds. New CO observations were carried out with the IRAM 30-m and ARO 12-m telescopes, and the near-infrared observations were with Palomar 200-inch telescope. The near-infrared observations reveal shocked H2 emission from both supernova remnants, showing intricate networks of filaments on arcsec scales, following the bright ridges of the radio shells. The CO and CS linewidths, indicative of the shock speed, are 20-30 km/s. Both the near-infrared and millimeter-wave emission are attributed to shocks into gas with density >1e3 cm-3. Individual shock structures are resolved in the H2 emission, with inferred edge-on shock thickness ~1e17 cm, consistent with non-dissociative shocks into gas densities of 1e3-1e4 cm-3. Bright 1720 MHz OH masers are located within the shocked H2 gas complexes and highlight only l...

Reach, W T; Jarrett, T H; reach, William T.; Rho, Jeonghee

2004-01-01

30

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

31

Young supernova remnants  

International Nuclear Information System (INIS)

The interaction of the supernova with its environment leads to a rich set of phenomena, which can be observed at radio, optical, ultraviolet, and X-ray wavelengths. The purpose of this paper is to review these phenomena, with particular emphasis on the interpretation of recent observations of young supernova remnants. (orig./WL)

32

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

Science.gov (United States)

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

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

2006-02-01

33

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

International Nuclear Information System (INIS)

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?2.7-3.6 and M?2.8-5.3 for the W and E shells, respectively. We derive temperatures of 0.74+0.06 –0.05 keV and 0.8-1.8 keV for the W and E shells and an expansion velocity of ?900-950 km s–1. We estimate that the total energy (thermal and kinetic) involved in creating both shells is ?2 × 1055 erg, and their age is ?106 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.

34

Molecular clouds near supernova remnants  

International Nuclear Information System (INIS)

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

35

The Carina supernova remnant  

International Nuclear Information System (INIS)

It has been suggested that the non-thermal radio source G 286.8-0.5 is a supernova remnant in front of the Carina Nebula (NGC 3372), a view supported by the detection of X-ray emission from the region. Observations presented here show that the H? and H? lines are composed of two components, due to high- and low-velocity gas. The broad component of H? has a FWHM of 14.3 A corresponding to 655 km/s, while H? has a width of 10.0A (620 km/s). These high velocities are consistent with the supernova remnant hypothesis. (author)

36

Observability and diagnostics in the X-ray band of shock-cloud interactions in supernova remnants  

CERN Document Server

X-ray emitting features originating from the interaction of supernova shock waves with small interstellar gas clouds are revealed in many X-ray observations of evolved supernova remnants (e.g. Cygnus Loop and Vela), but their interpretation is not straightforward. We develop a self-consistent method for the analysis and interpretation of shock-cloud interactions in middle-aged supernova remnants, which can provide the key parameters of the system and the role of relevant physical effects like the thermal conduction, without the need to run ad-hoc numerical simulations and to bother of morphology details. We explore all the possible values of the shock speed and cloud density contrast relevant to middle-aged SNRs with a set of hydrodynamic simulations of shock-cloud interaction, including the effects of thermal conduction and radiative cooling. From the simulations, we synthesize spatially and spectrally resolved focal-plane data as they would be collected with XMM-Newton/EPIC, an X-ray instrument commonly use...

Orlando, S; Miceli, M; Zhou, X; Reale, F; Peres, G

2010-01-01

37

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

Science.gov (United States)

I will present results of our recent two- and three-dimensional Particle-In-Cell simulations of magnetic-turbulence production by cosmic-ray ions drifting upstream of supernova remnant shocks. These studies' aim is twofold: test recent predictions of strong amplification in short wavelength, non-resonant wave modes, and study the subsequent evolution of the magnetic turbulence, including its backreaction on cosmic-ray trajectories. We confirm that the drifting cosmic rays give rise to a turbulent magnetic field, but show that an oblique filamentary mode grows more rapidly than the non-resonant parallel modes found in analytical theory. The field perturbations grow more slowly than estimated using a quasi-linear analytical approach for the parallel plane-wave mode, and saturate in amplitude at deltaB/B approximately equal to 1. The backreaction of the magnetic turbulence on the particles leads to an alignment of the bulk-flow velocities of the cosmic rays and the background medium. This is an essential characteristic of cosmic ray-modified shocks: the upstream flow speed is continuously changed by the cosmic rays. The reduction of relative drift between cosmic rays and background medium accounts for the saturation of the instability at only moderate magnetic-field amplitudes. It is possible that the prolonged magnetic field growth observed in recent MHD simulations results from a cosmic-ray current assumed to be constant and thus immune to the backreaction from the turbulent field. We speculate that the parallel plane-wave mode found in analytical treatments very quickly leads co filamentation, which we observe in our PIC modeling and is also apparent in the MHD simulations.

Stroman, Thomas; Niemiec, Jacek; Pohl, Martin; Nishikawa, Ken-ichi

2008-01-01

38

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

International Nuclear Information System (INIS)

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

39

Spectra of Magnetic Fluctuations and Relativistic Particles Produced by a Nonresonant Wave Instability in Supernova Remnant Shocks  

Science.gov (United States)

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

Vladimirov, Andrey E.; Bykov, Andrei M.; Ellison, Donald C.

2009-09-01

40

Spectra of magnetic fluctuations and relativistic particles produced by a nonresonant wave instability in supernova remnant shocks  

CERN Document Server

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

Vladimirov, Andrey E; Ellison, Donald C

2009-01-01

 
 
 
 
41

Cosmic Ray Acceleration at the Forward Shock in Tycho's Supernova Remnant: Evidence from Chandra X-ray Observations  

CERN Document Server

We present evidence for cosmic ray acceleration at the forward shock in Tycho's supernova remnant (SNR) from three X-ray observables: (1) the proximity of the contact discontinuity to the forward shock, or blast wave, (2) the morphology of the emission from the rim of Tycho, and (3) the spectral nature of the rim emission. We determine the locations of the blast wave (BW), contact discontinuity (CD), and reverse shock (RS) around the rim of Tycho's supernova remnant using a principal component analysis and other methods applied to new Chandra data. The azimuthal-angle-averaged radius of the BW is 251". For the CD and RS we find average radii of 241" and 183", respectively. Taking account of projection effects, we find ratios of 1:0.93:0.70 (BW:CD:RS). We show these values to be inconsistent with adiabatic hydrodynamical models of SNR evolution. The CD:BW ratio can be explained if cosmic ray acceleration of ions is occurring at the forward shock. The RS:BW ratio, as well as the strong Fe Ka emission from the T...

Warren, J S; Badenes, C; Ghavamian, P; McKee, C F; Moffett, D; Plucinsky, P P; Rakowski, C; Reynoso, E; Slane, P O

2005-01-01

42

Missing supernova remnants  

International Nuclear Information System (INIS)

The discrepancy between supernova explosion rates estimated from statistics of pulsars and of supernova remnants (SNRs) is well conciliated, if we consider that a considerable fraction of SNRs is missing. As the causes of missing SNRs, we have examined two cases, i.e., the supernova explosions have occurred in a hot, rarefied ambient matter or within stellar wind bubbles. For both cases, usual shell-forming radio SNRs are not expected at the stage, when their radii are smaller than --30 pc. From these, we predict the supernova rate would be (2 -- 5) x r sub(SN)sup(ob), with r sub(SN)sup(ob) being the rate determined from the counts of radio SNRs. This rate is not inconsistent with the one determined from pulsar statistics. Some other problems on missing SNRs will also be discussed. (author)

43

Acceleration of cosmic rays at supernova remnant shocks: constraints from gamma-ray observations  

CERN Document Server

In the past few years, gamma-ray astronomy has entered a golden age. At TeV energies, only a handful of sources were known a decade ago, but the current generation of ground-based imaging atmospheric Cherenkov telescopes has increased this number to more than one hundred. At GeV energies, the Fermi Gamma-ray Space Telescope has increased the number of known sources by nearly an order of magnitude in its first 2 years of operation. The recent detection and unprecedented morphological studies of gamma-ray emission from shell-type supernova remnants is of great interest, as these analyses are directly linked to the long standing issue of the origin of the cosmic-rays. However, these detections still do not constitute a conclusive proof that supernova remnants accelerate the bulk of Galactic cosmic-rays, mainly due to the difficulty of disentangling the hadronic and leptonic contributions to the observed gamma-ray emission. In this talk, I will review the most relevant cosmic ray related results of gamma ray astr...

Lemoine-Goumard, Marianne

2011-01-01

44

Supernova remnants: the X-ray perspective  

Science.gov (United States)

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 the products of fresh nucleosynthesis, and resulted in the identification of regions near shock fronts that emit X-ray synchrotron radiation. Since X-ray synchrotron radiation requires 10-100 TeV electrons, which lose their energies rapidly, the study of X-ray synchrotron radiation has revealed those regions where active and rapid particle acceleration is taking place. In this text all the relevant aspects of X-ray emission from supernova remnants are reviewed and put into the context of supernova explosion properties and the physics and evolution of supernova remnants. The first half of this review has a more tutorial style and discusses the basics of supernova remnant physics and X-ray spectroscopy of the hot plasmas they contain. This includes hydrodynamics, shock heating, thermal conduction, radiation processes, non-equilibrium ionization, He-like ion triplet lines, and cosmic ray acceleration. The second half offers a review of the advances made in field of X-ray spectroscopy of supernova remnants during the last 15 year. This period coincides with the availability of X-ray imaging spectrometers. In addition, I discuss the results of high resolution X-ray spectroscopy with the Chandra and XMM-Newton gratings. Although these instruments are not ideal for studying extended sources, they nevertheless provided interesting results for a limited number of remnants. These results provide a glimpse of what may be achieved with future microcalorimeters that will be available on board future X-ray observatories. In discussing the results of the last 15 years I have chosen to discuss a few topics that are of particular interest. These include the properties of Type Ia supernova remnants, which appear to be regularly shaped and have stratified ejecta, in contrast to core collapse supernova remnants, which have patchy ejecta distributions. For core collapse supernova remnants I discuss the spatial distribution of fresh nucleosynthesis products, but also their properties in connection to the neutron stars they contain. For the mature supernova remnants I focus on the prototypal supernova remnants Vela and the Cygnus Loop. And I discuss the interesting class of mixed-morphology remnants. Many of these mature supernova remnants contain still plasma with enhanced ejecta abundances. Over the last five years it has also become clear that many mixed-morphology remnants contain plasma that is overionized. This is in contrast to most other supernova remnants, which contain underionized plasmas. This text ends with a review of X-ray synchrotron radiation from shock regions, which has made it clear that some form of magnetic-field amplification is operating near shocks, and is an indication of efficient cosmic-ray acceleration.

Vink, Jacco

2012-12-01

45

Electron acceleration in a nonlinear shock model with applications to supernova remnants  

Science.gov (United States)

Monte Carlo calculations are presented of ion and electron spectra produced by Fermi acceleration in a steady state plane parallel modified shock for Mach numbers of 170 and 43. The simulation assumes isotropic elastic scattering in the local fluid frame, consistent with results from plasma simulations. The shock structure is calculated taking into account the back pressure of accelerated ions, and includes self-consistent pickup and acceleration of thermal ions. Results are described for two dependences of scattering mean free path on rigidity. It is shown that these shocks are extremely efficient, with up to 98 percent of the entering energy flux emerging as relativistic ions. Electron spectra are steeper than ion spectra at virtually all energies relevant for radio emission from SN remnants (0.3-30 GeV) and are slightly concave upward.

Ellison, Donald C.; Reynolds, Stephen P.

1991-11-01

46

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

International Nuclear Information System (INIS)

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

47

Shock Velocities in Kepler's Supernova Remnant, and Spectra of Progenitor-Companion Candidates  

Science.gov (United States)

Kepler's SNR is the product of a Type Ia explosion (SN1604). Unlike Tycho or SN1006, the blast wave around Kepler's SNR is interacting with circumstellar material, which makes it the most likely example of a Type Ia supernova from a single degenerate channel. Unfortunately, the distance to Kepler is poorly determined, and an exhaustive search for the companion to the supernova progenitor has never been conducted. We have recently obtained second epoch HST images that have allowed us to accurately measure the proper motion of the Balmer filaments tracing the shock front in Kepler. We propose to obtain spectra of these filaments with GMOS on Gemini-S to measure the H(alpha) line widths, and thereby determine the shock velocities at each position. The shock velocities and the proper motions will provide an accurate distance to Kepler's SNR. We also propose to observe and characterize all the stars near the explosion center that have magnitudes less than V~21. If Kepler formed via the single degenerate channel, then our sample will include essentially all plausible companion stars brighter than white dwarfs.

Sankrit, Ravi; Blair, William P.; Long, Knox S.; Winkler, Frank

2014-02-01

48

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

49

Supernova remnants: the X-ray perspective  

CERN Document Server

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 the products of fresh nucleosynthesis, and resulted in the identification of regions near shock fronts that emit X-ray synchrotron radiation. In this text all the relevant aspects of X-ray emission from supernova remnants are reviewed and put into the context of supernova explosion properties and the physics and evolution of supernova remnants. The first half of this review has a more tutorial style and discusses the basics of supernova remnant physics and thermal and non-thermal X-ray emission. The second half offers a review of the recen...

Vink, Jacco

2011-01-01

50

Efficient Collisionless Electron Heating at the Reverse Shocks of Young Supernova Remnants Revealed by Fe-K Emission Diagnostics  

Science.gov (United States)

Although collisionless shocks are ubiquitous in astrophysics, their fundamental properties are still poorly understood. In particular, the process known as collisionless electron heating is one of the main open issues in shock physics. Here we present Suzaku deep observations of the supernova remnants (SNRs) Tycho and 0509-67.5, showing the first robust evidence for efficient collisionless heating of electrons at their reverse shocks. We detect Fe K-beta (3p->1s) fluorescence emission at ~7.1 keV, which is expected only from low-ionization plasma where Fe ions still have many 3p electrons, and so key to diagnosing the plasma state of the immediate postshock ejecta. For Tycho SNR, we reveal that the K-beta emission peaks at a smaller radius than Fe K-alpha (2p->1s) fluorescence dominated by a relatively highly-ionized component. This updates the reverse shock radius of this SNR previously determined using the high-resolution Chandra image. Comparison with our hydrodynamical simulations requires the electron temperature at the reverse shock front to be more than 10 keV, about 1000 times higher than expected from Coulomb collisions alone.

Yamaguchi, Hiroya; Eriksen, Kristoffer A.; Badenes, Carles; Hughes, John Patrick; Brickhouse, Nancy S.; Foster, Adam; Patnaude, Daniel; Petre, Robert; Slane, Patrick O.; Smith, Randall K.

2014-08-01

51

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

CERN Document Server

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

52

Radioactivity and Electron Acceleration in Supernova Remnants  

CERN Document Server

We argue that decays of radioactive nuclei related to $^{44}$Ti and $^{56}$Ni ejected during supernova explosions provide a vast pool of mildly relativistic positrons and electrons which can be further accelerated to ultrarelativistic energies by reverse and forward shocks - the second phenomenon related to the supernova explosions. We demonstrate the feasibility of this interesting link, which can be a clue for solution of the well known theoretical problem of electron injection in relation to the diffusive shock acceleration in supernova remnants, for the brightest radio source Cas A.

Zirakashvili, V N

2010-01-01

53

Double features in radio supernova remnants  

International Nuclear Information System (INIS)

The two-component magnetic field perturbations that will develop after passage of a shock wave may engender double strong--strong and strong--weak features in the radio maps of old supernova remnants. The distance separating the components provides an independent estimate of the magnetic field direction and strength

54

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

CERN Document Server

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

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

2010-01-01

55

Antiprotons Produced in Supernova Remnants  

CERN Document Server

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

56

Antiprotons Produced in Supernova Remnants  

Science.gov (United States)

We present the energy spectrum of an antiproton cosmic ray (CR) component calculated on the basis of the nonlinear kinetic model of CR production in supernova remnants (SNRs). The model includes the reacceleration of antiprotons already existing in the interstellar medium as well as the creation of antiprotons in nuclear collisions of accelerated protons with gas nuclei and their subsequent acceleration by SNR shocks. It is shown that the production of antiprotons in SNRs produces a 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 5. The calculated antiproton spectrum is 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 secondary nuclei and show that the measured boron-to-carbon ratio is consistent with the significant SNR contribution.

Berezhko, E. G.; Ksenofontov, L. T.

2014-08-01

57

Pulsar Evolution within a Composite Supernova Remnant  

Science.gov (United States)

Supernova remnants have been observed expanding into a non-uniform density ISM. Such expansion creates asymmetry within the remnant, and we attempt to understand how this asymmetric expansion propagates through a system containing an active pulsar wind nebula. We are particularly interested in applying computational methods to such systems in order to recreate and understand the dynamics driving the formation of observed SNRs and their PWNe. We present here a two-dimensional hydrodynamics simulation of a SNR expanding into a uniform density gradient. The remnant contains an active PWN with a translational velocity of approximately 300 km/s which is expanding into freely expanding, unshocked supernova ejecta. We consider, in particular, the reverse-shock interaction state in which the wind nebula is crushed by the asymmetric reverse shock, and investigate the morphology and mixing of thermal and relativistic gas in the context of observed systems including G327.1-1.1.

Kolb, Christopher; Blondin, John M.; Slane, Patrick O.; Temim, Tea

2014-08-01

58

X-ray haloes around supernova remnants  

International Nuclear Information System (INIS)

Recent observations of the Cas-A supernova remnant have shown X-ray emissions not only from the interior, but also from a fainter 'halo' extending beyond what is normally regarded as the outer boundary, or shock front. The authors suggest that this may be due to the diffusion of energetic, charged particles out of the remnant giving rise to precursor structure of the type predicted by the theory of diffusive shock acceleration. If this is the case we are seeing thermal emission from ambient gas heated by compression and wave dissipation. (author)

59

AKARI NEAR-INFRARED SPECTRAL OBSERVATIONS OF SHOCKED H2 GAS OF THE SUPERNOVA REMNANT IC 443  

International Nuclear Information System (INIS)

We present near-infrared (2.5-5.0 ?m) spectra of shocked H2 gas in the supernova remnant IC 443, obtained with the satellite AKARI. Three shocked clumps-known as B, C, and G-and one background region were observed, and only H2 emission lines were detected. Except in clump B, the extinction-corrected level population shows the ortho-to-para ratio of ?3.0. From the level populations of clumps C and G-both the one obtained with AKARI and the one extended with previous mid-infrared observations-we found that the ? = 0 levels are more populated than the ?>0 levels at a fixed level energy, which cannot be reproduced by any combination of H2 gas in local thermodynamic equilibrium. The populations are described by the two-density power-law thermal admixture model, revised to include the collisions with H atoms. We attributed the lower (n(H2)=102.8-103.8 cm-3) and higher (n(H2)=105.4-105.8 cm-3) density gases to the shocked H2 gas behind C-type and J-type shocks, respectively, based on several arguments including the obtained high H I abundance n(H I)/n(H2) = 0.01. Under the hierarchical picture of molecular clouds, the C-type and J-type shocks likely propagate into 'clumps' and 'clouds' (interclump media), respectively. The power-law index b of 1.6 and 3.5, mainly determined by the lower density gas, is attributed to the shock-vely gas, is attributed to the shock-velocity diversity, which may be a natural result during shock-cloud interactions. According to our results, H2 ? = 1 ? 0 S(1) emission is mainly from J shocks propagating into interclump media. The H2 emission was also detected at the background region, and this diffuse H2 emission may originate from the collisional process in addition to ultraviolet photon pumping.

60

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

Science.gov (United States)

Although efficient cosmic-ray acceleration to energies greater than 100 TeV at young supernova remnants (SNRs) has been established observationally, the dominance of protons expected by the non-linear diffusive shock acceleration (NL-DSA) theory at the highest energy range has not been confirmed unambiguously. The uncertainties arise mainly from the fact that the predicted radiation, particularly the ratio of inverse-Compton (IC) from electrons to neutral pion decay from protons, depends importantly on poorly constrained environmental and model parameters. On the observational side, the broadband emission from radio to TeV gamma-rays is measured with varying spatial and spectral resolution. The efficiency of NL-DSA and the composition of accelerated particles can only be determined when the amorphous mix of data is analyzed consistently with the acceleration model. We present here a 3-dimensional model of Type Ia SNRs where the hydrodynamical evolution of the remnant is modeled consistently with NL-DSA including particle escape, diffusion outside of the forward shock, and particle interactions with the ambient material. We include synchrotron emission and cooling, bremsstrahlung radiation, neutral pion production, IC, and Coulomb energy-loss. Boardband spectra have been calculated for typical environments including a dense region of gas external to a 1000 year old SNR. Our model can adapt to various SNR environments and predict cosmic ray spectra and multi-wavelength morphology in projected images for instruments with varying spatial and spectral resolutions. We show the importance of measurements in the hard X-ray, GeV and >10; TeV gamma-ray band for understanding the acceleration mechanism. The Gamma Ray Large Area Telescope (GLAST) is expected to fill in the GeV energy gap which is vital to the verification of the SNR origin of Galactic cosmic rays.

Lee, Shiu-Hang Herman; Kamae, T.; Ellison, D.

2008-03-01

 
 
 
 
61

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

Science.gov (United States)

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.

Dieckmann, M. E.; Bret, A.; Sarri, G.; Perez Alvaro, E.; Kourakis, I.; Borghesi, M.

2012-08-01

62

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)

63

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

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

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

66

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

International Nuclear Information System (INIS)

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

67

Observational Constraints on Cosmic Ray Acceleration in Supernova Remnants  

Science.gov (United States)

Over the past few years, observations in the X-ray and gamma-ray bands, coupled with theoretical investigations, have led to important new insights into the process of particle acceleration at high speed shocks in supernova remnants. In this presentation I will review results largely from the X-ray band that reveal the presence of shock-accelerated relativistic electrons and amplified magnetic fields at these shock fronts. Evidence for shock-accelerated protons, although less direct, appears in the form of modifications to the dynamical evolution of young remnants, particularly SN1006 and the Tycho supernova remnant. As time permits, I will examine other observational topics bearing on the small-scale angular structure and temporal variations in the X-ray synchrotron emission, and particle acceleration at the reverse shocks of remnants. )

Hughes, John P.

2010-02-01

68

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  

CERN Document Server

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 10^{51} 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 10^{51} erg a few thousand years ago.

Obergaulinger, M; Müller, E; Smoot, G F

2014-01-01

69

Formation of supernova remnants: The pre-blast-wave phase  

International Nuclear Information System (INIS)

The effect of stellar structure on supernova remnant formation is studied with a series of computer models of a 1051 erg explosion in a 15 M/sub sun/ star. We find that immediately after the explosion shock wave travels down a steep density gradient, the material in the gradient goes into free expansion, forming a collapsible piston. At the outer edge of such a piston are two shock waves: the expanding supernova shock and a reverse shock moving back into the collapsible piston. Until the piston is completely collapsed it is Rayleigh-Taylor stable, but after collpse the inner material behaves as a massive piston and the interface is R-T unstable. If there is a significant mass in an external density gradient, the material between the supernova shock moving out through the interstellar medium and the reverse shock will be a singificant source of x-rays during the pre--blast-wave phase of remnant formation

70

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

71

Hadronic Gamma Rays from Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A gas cloud near a supernova remnant (SNR) provides a target for pp-collisions leading to subsequent gamma-ray emission through neutral pion decay. The assumption of a power-law ambient spectrum of accelerated particles with index near -2 is usually built into models predicting the spectra of very-high energy (VHE) gamma-ray emission from SNRs. However, if the gas cloud is located at some distance from the SNR shock, this assumption is not necessarily correct. In this case, ...

Moskalenko, I. V.; Porter, T. A.; Malkov, M. A.; Diamond, P. H.

2007-01-01

72

The molecular emission from old supernova remnants  

CERN Document Server

Supernovae constitute a critical source of energy input to the interstellar medium (ISM). In this short review, we focus on their latest phase of evolution, the supernova remnants (SNRs). We present observations of three old SNRs that have reached the phase where they interact with the ambient ISM: W28, IC443, and 3C391. We show that such objects make up clean laboratories to constrain the physical and chemical processes at work in molecular shock environments. Our studies subsequently allow us to quantify the impact of SNRs on their environment in terms of mass, momentum, and energy dissipation. In turn, their contribution to the energy balance of galaxies can be assessed. Their potential to trigger a further generation of star formation can also be investigated. Finally, our studies provide strong support for the interpretation of gamma-ray emission in SNRs, a crucial step to answer questions related to cosmic rays population and acceleration.

Gusdorf, Antoine; Anderl, Sibylle; Hezareh, Talayeh

2014-01-01

73

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

74

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

75

Evolution of Magnetic Fields in Supernova Remnants  

CERN Document Server

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

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

2008-01-01

76

Einstein Observations of Galactic supernova remnants  

Science.gov (United States)

This paper summarizes the observations of Galactic supernova remnants with the imaging detectors of the Einstein Observatory. X-ray surface brightness contours of 47 remnants are shown together with gray-scale pictures. Count rates for these remnants have been derived and are listed for the HRI, IPC, and MPC detectors.

Seward, Frederick D.

1990-01-01

77

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

78

X-ray imaging: supernova remnants  

International Nuclear Information System (INIS)

The Einstein Observatory has provided astronomers with the first opportunity to obtain optical quality images of extended X-ray sources. Such pictures of supernova remnants, for example, yield a wealth of information on the dynamics and evolution of the expanding blast wave, the possible collapsed remnants of the exploded star, and the structure of the interstellar medium. The author reviews imaging observation of over 50 supernova remnants obtained during the first year of the Observatory's operation. Although analysis of these results is still in its infancy, it is already possible to draw important conclusions regarding models for stellar explosions, remnant evolution, neutron star formation, and the interstellar medium. (Auth.)

79

On the radio spectra of supernova remnants  

CERN Document Server

The theoretical fundamentals of formation of the supernova remnant (SNR) continuum radio spectra are presented in this review. Mainly based on the Fermi 1 theory - also known as diffuse shock acceleration (DSA) - the different shapes (linear or curved in log-log scale) of SNR radio spectra are predicted for both young and evolved SNRs. On the other hand, some particular forms of spectra of older SNRs can be predicted by including the additional processes such as Fermi 2 acceleration mechanism or thermal bremsstrahlung radiation. Also, all of these theoretically predicted forms of radio spectra are compared with real spectra obtained from observations. Finally this review can represent some kind of "atlas" with initial patterns for the different kinds of SNR radio spectra - it should be helpful for radio astronomers in their interpretation of the observed radio spectra.

Uroševi?, Dejan

2014-01-01

80

Laser experiments to simulate supernova remnants  

International Nuclear Information System (INIS)

An experiment using a large laser facility to simulate young supernova remnants (SNRs) is discussed. By analogy to the SNR, the laboratory system includes dense matter that explodes, expansion and cooling to produce energetic, flowing plasma, and the production of shock waves in lower-density surrounding matter. The scaling to SNRs in general and to SN1987A in particular is reviewed. The methods and results of x-ray radiography, by which the system in diagnosed, are discussed. The data show that the hohlraum used to provide the energy for explosion does so in two ways--first, through its radiation pulse, and second, through an additional impulse that is attributed to stagnation pressure. Attempts to model these dynamics are discussed. (c) 2000 American Institute of Physics

 
 
 
 
81

Radio continuum observations of large supernova remnants  

International Nuclear Information System (INIS)

Polarization and morphology of large (old) supernova remnants beyond 1 GHz can be easily observed with the 100-m telescope at Effelsberg. The authors briefly describe the ongoing observation program. (Auth.)

82

Origin of Radially Aligned Magnetic Fields in Young Supernova Remnants  

CERN Document Server

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

Inoue, Tsuyoshi; Ohira, Yutaka; Yamazaki, Ryo

2013-01-01

83

X-ray spectroscopy of supernova remnants  

International Nuclear Information System (INIS)

The information which can be obtained from X-ray spectroscopy of supernova remnants is considered. The fitting of X-ray detector counts to models of the incident spectrum is discussed, and the types of thermal emission models generally employed are presented, including the power law, black body, and thermal bremsstrahlung models of the continua and models of the emission of a hot, optically thin plasma in collisional equilibrium. Observations of 12 supernova remnants made with the Solid State Spectrometer on board the Einstein Observatory are reported, and metal abundances inferred from the lines of the eight remnants showing thermal spectra are summarized. Questions raised by the failure to observe the overabundance of Fe predicted by stellar evolution and hydrodynamic modeling are discussed, and the need to develop more detailed models of the conditions in a supernova remnant in order to interpret the X-ray spectra is noted

84

Excited-state OH Masers and Supernova Remnants  

CERN Document Server

The collisionally pumped, ground-state 1720 MHz maser line of OH is widely recognized as a tracer for shocked regions and observed in star forming regions and supernova remnants. Whereas some lines of excited states of OH have been detected and studied in star forming regions, the subject of excited-state OH in supernova remnants -- where high collision rates are to be expected -- is only recently being addressed. Modeling of collisional excitation of OH demonstrates that 1720, 4765 and 6049 MHz masers can occur under similar conditions in regions of shocked gas. In particular, the 6049 and 4765 MHz masers become more significant at increased OH column densities where the 1720 MHz masers begin to be quenched. In supernova remnants, the detection of excited-state OH line maser emission could therefore serve as a probe of regions of higher column densities. Using the Very Large Array, we searched for excited-state OH in the 4.7, 7.8, 8.2 and 23.8 GHz lines in four well studied supernova remnants with strong 172...

Pihlström, Ylva M; Sjouwerman, Loránt O; Zschaechner, Laura K; Lockett, Philip B; Elitzur, Moshe

2008-01-01

85

Excited-State OH Masers and Supernova Remnants  

Science.gov (United States)

The collisionally pumped, ground-state 1720 MHz maser line of OH is widely recognized as a tracer for shocked regions and observed in star-forming regions and supernova remnants. Whereas some lines of excited states of OH have been detected and studied in star-forming regions, the subject of excited-state OH in supernova remnants-where high collision rates are to be expected-is only recently being addressed. Modeling of collisional excitation of OH demonstrates that 1720, 4765, and 6049 MHz masers can occur under similar conditions in regions of shocked gas. In particular, the 6049 and 4765 MHz masers become more significant at increased OH column densities where the 1720 MHz masers begin to be quenched. In supernova remnants, the detection of excited-state OH line maser emission could therefore serve as a probe of regions of higher column densities. Using the Very Large Array, we searched for excited-state OH in the 4.7, 7.8, 8.2, and 23.8 GHz lines in four well-studied supernova remnants with strong 1720 MHz maser emission (Sgr A East, W28, W44 and IC 443). No detections were made, at typical detection limits of around 10 mJy beam-1. The search for the 6 GHz lines were done using Effelsberg since the VLA receivers did not cover those frequencies, and are reported on in an accompanying letter (Fish and coworkers). We also cross-correlated the positions of known supernova remnants with the positions of 1612 MHz maser emission obtained from blind surveys. No probable associations were found, perhaps except in the Sgr A East region. The lack of detections of excited-state OH indicates that the OH column densities suffice for 1720 MHz inversion but not for inversion of excited-state transitions, consistent with the expected results for C-type shocks.

Pihlström, Ylva M.; Fish, Vincent L.; Sjouwerman, Loránt O.; Zschaechner, Laura K.; Lockett, Philip B.; Elitzur, Moshe

2008-03-01

86

Instabilities and Clumping in Type Ia Supernova Remnants  

CERN Document Server

We present two-dimensional high-resolution hydrodynamical simulations in spherical polar coordinates of a Type Ia supernova interacting with a constant density interstellar medium. The ejecta are assumed to be freely expanding with an exponential density profile. The interaction gives rise to a double-shocked structure susceptible to hydrodynamic instabilities. The Rayleigh-Taylor instability initially grows, but the Kelvin-Helmholtz instability takes over, producing vortex rings. The nonlinear instability initially evolves toward longer wavelengths and eventually fades away when the reverse shock front is in the flatter part of the supernova density distribution. Based on observations of X-ray knots and the protrusion in the southeast outlin of Tycho's supernova remnant, we include clumping in the ejecta. The clump interaction with the reverse shock induces Rayleigh-Taylor and Kelvin-Helmholtz instabilities on the clump surface that facilitate fragmentation. In order to survive crushing and to have a bulging...

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

2001-01-01

87

Interaction of Rayleigh-Taylor Fingers and Circumstellar Clodlets in Young Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We discover a new dynamical mechanism that significantly enhances the growth of Rayleigh-Taylor fingers developed near the contact interface between the supernova ejecta and swept-up ambient gas in young supernova remnants if the supernova remnant expands into a clumpy (cloudy) circumstellar medium. Our numerical simulation demonstrates that large Rayleigh-Taylor fingers can obtain a sufficient terminal velocity to protrude through the forward shock front by taking extra kin...

Jun, Byung-il; Jones, T. W.; Norman, Michael L.

1996-01-01

88

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

CERN Document Server

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

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

2003-01-01

89

Interaction of a Pulsar Wind with the Expanding Supernova Remnant  

CERN Document Server

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 find three independent instabilities in the interaction region between the pulsar wind and the expanding supernova remnant. The most important instability develops as the shock driven by the pulsar bubble becomes accelerated ($r \\propto t^{6/5}$). The instability produces pronounced filamentary structures that resemble the observed filaments in the Crab Nebula. Our numerical simulations can reproduce important observational features of the Crab Nebula. The high density heads in the R-T finger tips are produced because of the compressibility o...

Jun, B I

1997-01-01

90

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

91

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

92

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

93

Some implications of the X-ray data from old supernova remnants  

International Nuclear Information System (INIS)

Several old supernova remnants emit soft X-rays. With certain assumptions, and using a standard adiabatic shock-wave model, values for the initial blast energy of a supernova and the age of its remnant may be estimated. These parameters are evaluated using the most recently available X-ray and radio results for four old supernova remnants. The data imply high ratios of initial blast energy to interstellar density and comparatively young ages for the remnants. These conclusions, while at variance with some earlier estimates based on optical and radio data, support the results of a statistical analysis of the most recent catalogue of radio remnants. Predicted X-ray fluxes for other supernova remnants lying within 6 kpc of the Sun are presented as a guide to future observational programmes. (author)

94

Reacceleration of electrons in supernova remnants  

CERN Document Server

The radio spectra of many shell-type supernova remnants show deviations from those expected on theoretical grounds. In this paper we determine the effect of stochastic reacceleration on the spectra of electrons in the GeV band and at lower energies, and we investigate whether or not reacceleration can explain the observed variation of radio spectral indices. We explicitely calculate the momentum diffusion coefficient for 3 types of turbulence expected downstream of the forward shock: fast-mode waves, small-scale non-resonant modes, and large-scale modes arising from turbulent dynamo activity. Noting that low-energy particles are efficiently coupled to the quasi-thermal plasma, a simplified cosmic-ray transport equation can be formulated and is numerically solved. Only fast-mode waves can provide momentum diffusion fast enough to significantly modify the spectra of particles. Using a synchrotron emissivity that accurately reflects a highly turbulent magnetic field, we calculate the radio spectral index and fin...

Pohl, M; Telezhinsky, I

2014-01-01

95

Gamma-ray Emission from Crushed Clouds in Supernova Remnants  

CERN Document Server

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 neutral pions 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; Funk, Stefan; Tajima, Hiroyasu; Tanaka, Takaaki

2010-01-01

96

Far Ultraviolet Spectral Images of the Vela Supernova Remnant  

CERN Document Server

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

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

2006-01-01

97

Far-Ultraviolet Spectral Images of the Vela Supernova Remnant  

Science.gov (United States)

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

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

2006-06-01

98

Dust in Historical Galactic Type Ia Supernova Remnants with Herschel  

CERN Document Server

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

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

2011-01-01

99

Particle acceleration in galactic supernova remnants  

International Nuclear Information System (INIS)

This paper discusses the radio spectral indices of Galactic SNRs in relation to the particle acceleration mechanisms responsible for their radio emission. Young, bright shell remnants generally have spectral indices a larger than the 0.5 expected from basic shock acceleration theory. Fainter, older shell remnants have a wide range of a. Evidence on whether or not particle acceleration is continuing in SNRs is also discussed

100

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

 
 
 
 
101

Central Compact Objects in Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2003-01-01

102

A search for young Galactic supernova remnants  

Science.gov (United States)

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

Misanovic, Zdenka; Cram, Lawrence; Green, Anne

2002-09-01

103

The puzzling compact sources in supernova remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

X-ray images of some young supernova remnants show bright point sources which have not been detected in radio, optical and gamma-ray bands. Despite the similarity of the X-ray spectra of these objects, they show a variety of temporal properties. Most likely, they are neutron stars whose properties (spin periods? magnetic fields? environments?) are different from those of radio and/or gamma-ray pulsars. We present an overview of observational results on several objects of thi...

Pavlov, G. G.; Sanwal, D.; Garmire, G. P.; Zavlin, V. E.

2001-01-01

104

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

International Nuclear Information System (INIS)

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

105

Antlia Supernova Remnant in Far-ultraviolet  

Science.gov (United States)

Antlia supernova remnant (l = 276.52°, b = +19.05°) was recently discovered by McCullough et al. (2002), and its angular size ( 24°) is comparable to Monogem Ring. It shows a diffuse appearance in soft X-ray, which is anti-correlated with 100 ?m infrared emission and surrounded by annular enhancements in H?. We present the far-ultraviolet view of the remnant observed with Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR), also known as Far-ultraviolet IMaging Spectrograph (FIMS). C IV ? and Si II emission lines were detected in the remnant region, and their emission-line maps show a rough anti-correlation with a soft X-ray map (ROSAT All Sky Survey 0.25 keV map).

Shinn, Jong-Ho; Min, K. W.; Seon, K.; Lim, Y.; Edelstein, J.; Han, W.; Sankrit, R.; FIMS Team at KAIST; FIMS Team at KASI; SPEAR Team at SSL

2006-09-01

106

Future GLAST observations of Supernova remnants and Pulsar Wind Nebulae  

CERN Document Server

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

Funk, S

2007-01-01

107

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

108

Late-time hohlraum pressure dynamics in supernova remnant experiments  

International Nuclear Information System (INIS)

It is shown that laser driven hohlraums obtain significant internal pressures which affect the hydrodynamics of high-energy density shock-tube experiments. By incorporating this previously neglected hohlraum pressure effect (in addition to the usual x-ray drive) into computer simulations which model the NOVA laser driven supernova remnant experiment [R. P. Drake, S. G. Glendinning, K. Estabrook, B. A. Remington, R. McCray, R. J. Williams, L. J. Suter, T. B. Smith, J. J. Carroll III, R. A. London, and E. Liang, Phys. Rev. Lett. 81, 2068 (1998)], calculations are able to reproduce the observed structure of hydrodynamic features

109

Late-time hohlraum pressure dynamics in supernova remnant experiments  

Science.gov (United States)

It is shown that laser driven hohlraums obtain significant internal pressures which affect the hydrodynamics of high-energy density shock-tube experiments. By incorporating this previously neglected hohlraum pressure effect (in addition to the usual x-ray drive) into computer simulations which model the NOVA laser driven supernova remnant experiment [R. P. Drake, S. G. Glendinning, K. Estabrook, B. A. Remington, R. McCray, R. J. Williams, L. J. Suter, T. B. Smith, J. J. Carroll III, R. A. London, and E. Liang, Phys. Rev. Lett. 81, 2068 (1998)], calculations are able to reproduce the observed structure of hydrodynamic features.

Hurricane, O. A.; Glendinning, S. G.; Remington, B. A.; Drake, R. P.; Dannenberg, K. K.

2001-06-01

110

Supernova remnant W49B and its environment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study Gamma-ray supernova remnant W49B and its environment using recent radio and infrared data. {\\it Spitzer} IRS low resolution data of W49B shows shocked excitation lines of H$_{2}$ (0,0) S(0)-S(7) from the SNR-molecular cloud interaction. The H$_2$ gas is composed of two components with temperature of $\\sim$260 K and $\\sim$1060 K respectively. Various spectral lines from atomic and ionic particles are detected towards W49B. We suggest the ionic phase has an electron d...

Zhu, H.; Tian, W. W.; Zuo, P.

2014-01-01

111

Cosmic ray acceleration and escape from supernova remnants  

CERN Document Server

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

Bell, AR; Reville, B; Giacinti, G

2013-01-01

112

Spectrophotometry of HII Regions, Diffuse Ionized Gas and Supernova Remnants in M31: The Transition from Photo- to Shock-Ionization  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present results of KPNO 4-m optical spectroscopy of discrete emission-line nebulae and regions of diffuse ionized gas (DIG) in M31. Long-slit spectra of 16 positions in the NE half of M31 were obtained over a 5-15 kpc range in radial distance from the center of the galaxy. The spectra have been used to confirm 16 supernova remnant candidates from the Braun & Walterbos (1993) catalog. The slits also covered 46 HII regions which show significant differences among the variou...

Galarza, V. C.; Walterbos, R. A. M.; Braun, R.

1999-01-01

113

Thermal X-ray Spectra of Supernova Remnants  

CERN Document Server

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

114

On the evolution of supernova remnants: Pt. 2  

International Nuclear Information System (INIS)

Supernova explosions within wind-driven bubbles are studied with 2D hydrodynamical calculations. Two different density distributions for the ejecta are considered: (i) a smooth, unfragmented power-law stratification, and (ii) a fragmented distribution. As in 1D models, the presence of the shell of interstellar swept-up matter causes the rapid evolution of the remnant to the radiative phase. The main 2D effects, for both fragmented and unfragmented ejecta, include: (i) substantial chaotic deviations from a purely radial flow in the remnant interior, (ii) efficient turbulent mixing between the ejecta and the shocked wind, resulting in homogenization of the former wind cavity, and (iii) severe distortion of the wind-driven shell by cooling and Rayleigh-Taylor instabilities. (author)

115

Pulsar reenergization of old supernova remnant shells  

International Nuclear Information System (INIS)

The morphology of several unusual composite remnants are suggested to be affected by previously unrecognized interactions between high-velocity pulsars and old SNR shells, and the case of CTB 80 is pointed out as a likely example of such interactions. The interactions generate a new class of 'composite remnants' and furnish a novel method for the derivation of kinematic distances and SNR ages; this technique is noted to be especially useful when the pulsar has a measured spindown age or proper motion. It is predicted that a number of pulsars may interact with 80-100 pc radius 'superbubbles' produced by the combined action of winds and supernovae in OB associations. 74 refs

116

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

117

The puzzling compact sources in supernova remnants  

CERN Document Server

X-ray images of some young supernova remnants show bright point sources which have not been detected in radio, optical and gamma-ray bands. Despite the similarity of the X-ray spectra of these objects, they show a variety of temporal properties. Most likely, they are neutron stars whose properties (spin periods? magnetic fields? environments?) are different from those of radio and/or gamma-ray pulsars. We present an overview of observational results on several objects of this class -- the central sources of Cassiopeia A, RX J0852-4622, RCW 103, Puppis A, and PKS 1209-51/52 -- with emphasis on the recent Chandra observations.

Pavlov, G G; Garmire, G P; Zavlin, V E

2001-01-01

118

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

119

Modeling of the Radio Emission from the Vela Supernova Remnant  

CERN Document Server

Supernova remnants (SNRs) are widely considered to be sites of Galactic cosmic ray (CR) acceleration. Vela is one of the nearest Galactic composite SNRs to Earth accompanied by the Vela pulsar and its pulsar wind nebula (PWN) Vela X. The Vela SNR is one of the most studied remnants and it benefits from precise estimates of various physical parameters such as distance and age. Therefore, it is a perfect object for a detailed study of physical processes in SNRs. The Vela SNR expands into the highly inhomogeneous cloudy interstellar medium (ISM) and its dynamics is determined by the heating and evaporation of ISM clouds. It features an asymmetrical X-ray morphology which is explained by the expansion into two media with different densities. This could occur if the progenitor of the Vela SNR exploded close to the edge of the stellar wind bubble of the nearby Wolf-Rayet star $\\gamma^2$Velorum and hence one part of the remnant expands into the bubble. The interaction of the ejecta and the main shock of the remnant ...

Sushch, Iurii

2013-01-01

120

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

 
 
 
 
121

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

122

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

123

Modified equipartition calculation for supernova remnants  

CERN Document Server

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

124

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

125

Generation of Cosmic rays in Historical Supernova Remnants  

Directory of Open Access Journals (Sweden)

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

Sinitsyna V.Y.

2013-06-01

126

Supernova Remnants with NuSTAR: Highlights and new discoveries  

Science.gov (United States)

Young supernova remnants represent a unique laboratory for the study of supernova explosion dynamics and particle acceleration in the local universe. In the hard X-ray band probed by NuSTAR (3-79 keV), the continuum emission is thought to be dominated by synchrotron radiation from ~TeV electrons, while line emission at 68 and 78 keV is produced by the decay of radioactive 44Ti synthesized in the supernova explosion. Here we present highlights of the supernova remnant science from the first two years of the NuSTAR mission.

Grefenstette, Brian

2014-08-01

127

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 1052--1053 erg. Analysis of the light curve of the NGC 1058 supernova 1961v demonstrates that it represents a roughly-equal2 x 1052 erg outburst of a supermassive (roughly-equal103 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

128

Improved optical spectrophotometry of supernova remnants in M33  

Science.gov (United States)

Optical spectra of SNRs in M33 have been used to investigate abundance gradients and SNR evolution in this galaxy. Abundances of O, N, and S are derived from the spectra using new shock models by Dopita et al. (1984). The results for N and S show abundance gradients similar to those in NGC 300 and the Galaxy. The O abundances may be affected by possible contamination from H II regions and low-velocity shocks. Electron densities derived from the forbidden S II 6717 A/6731 A line ratio are used with a pressure equilibrium argument to estimate the initial explosion energy for each SNR. Evolutionary models for the remnants are investigated, and the distribution of the number of remnants with diameter is found to be consistent with free expansion of the SNRs to diameters of about 26 pc. The results may also be consistent with Sedov evolution if the ranges of initial supernova energies and surrounding interstellar medium densities are large enough.

Blair, W. P.; Kirshner, R. P.

1985-01-01

129

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

130

Spallative Nucleosynthesis in Supernova Remnants; 1, Analytical Estimates  

CERN Document Server

Spallative nucleosynthesis is thought to be the only process capable of producing significant amount of Beryllium (Be) in the universe. Therefore, both energetic particles (EPs) and nuclei to be spalled (most efficiently C, N and O nuclei in this case) are required, which indicates that supernovae (SNe) may be directly involved in the synthesis of the Be nuclei observed in the halo stars of the Galaxy. We apply current knowledge relating to supernova remnant (SNR) evolution and particle shock acceleration to calculate the total Be yield associated with a SN explosion in the interstellar medium, focusing on the first stages of Galactic chemical evolution (i.e. when metallicity Z < 0.01 Z_odot) We show that dynamical aspects must be taken into account carefully, and present analytical calculations of the spallation reactions induced by the EPs accelerated at both the forward and the reverse shocks following the SN explosion. Our results show that the production of Be in the early Galaxy is still poorly under...

Parizot, E; Parizot, Etienne; Drury, Luke

1999-01-01

131

Progress toward the Laboratory Simulation of Young Supernova Remnants  

International Nuclear Information System (INIS)

Progress in experiments to simulate the hydrodynamics of supernova remnants (SNRs) in the laboratory is reported. The experiment design involves shock heating of a dense material, which expands to become the ejecta that drive a blast wave through low-density foam. In the design, a variety of issues, such as radiative preheat of the unshocked matter, had to be addressed. A careful analysis of the scaling between hydrodynamic systems shows that the experiment is a good, scaled model of a local region in a young SNR. Measurements of the basic hydrodynamic behavior for two blast-wave velocities are nearly complete. Measurements of hydrodynamic instabilities at the contact surface between the ejecta and the low-density matter will commence in the near future. (c) 2000 The American Astronomical Society

132

Spectrophotometry of HII Regions, Diffuse Ionized Gas and Supernova Remnants in M31 The Transition from Photo- to Shock-Ionization  

CERN Document Server

We present results of KPNO 4-m optical spectroscopy of discrete emission-line nebulae and regions of diffuse ionized gas (DIG) in M31. Long-slit spectra of 16 positions in the NE half of M31 were obtained over a 5-15 kpc range in radial distance from the center of the galaxy. The spectra have been used to confirm 16 supernova remnant candidates from the Braun & Walterbos (1993) catalog. The slits also covered 46 HII regions which show significant differences among the various morphological types (center-brightened, diffuse, rings). Radial gradients in emission-line ratios such as [OIII]/H$\\beta$ and [OII]/[OIII] are observed most prominently in the center-brightened HII regions. These line ratio trends are either much weaker or completely absent in the diffuse and ring nebulae. The line ratio gradients previously seen in M31 SNRs (Blair, Kirshner, & Chevalier 1981; 1982) are well reproduced by our new data. The spectra of center-brightened HII regions and SNRs confirm previous determinations of the ra...

Galarza, V C; Braun, R

1999-01-01

133

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

134

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

135

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.)

136

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)

137

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

CERN Document Server

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

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

1999-01-01

138

Multi-dimensional simulations of the expanding supernova remnant of SN 1987A  

CERN Document Server

The expanding remnant from SN 1987A is an excellent laboratory for investigating the physics of supernovae explosions. There are still a large number of outstanding questions, such the reason for the asymmetric radio morphology, the structure of the pre-supernova environment, and the efficiency of particle acceleration at the supernova shock. We explore these questions using three-dimensional simulations of the expanding remnant between days 820 and 10,000 after the supernova. We combine a hydrodynamical simulation with semi-analytic treatments of diffusive shock acceleration and magnetic field amplification to derive radio emission as part of an inverse problem. Simulations show that an asymmetric explosion, combined with magnetic field amplification at the expanding shock, is able to replicate the persistent one-sided radio morphology of the remnant. We use an asymmetric Truelove & McKee progenitor with an envelope mass of $10 M_{\\sun}$ and an energy of $1.5 \\times 10^{44} J$. A termination shock in the...

Potter, T M; Reville, B; Ng, C -Y; Bicknell, G V; Sutherland, R S; Wagner, A Y

2014-01-01

139

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

140

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

 
 
 
 
141

MODIFIED EQUIPARTITION CALCULATION FOR SUPERNOVA REMNANTS  

Energy Technology Data Exchange (ETDEWEB)

Determination of the magnetic field strength in the interstellar medium is one of the more 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 the Zeeman effect and Faraday rotation, the equipartition or 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 its approximate character, it remains a useful tool, especially when there are no other data about the magnetic field in a source. In this paper, we give a modified calculation that we think is more appropriate for estimating magnetic field strengths and energetics in supernova remnants (SNRs). 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 magnetic field strengths of SNRs is available at http://poincare.matf.bg.ac.rs/{approx}arbo/eqp/.

Arbutina, B.; Urosevic, D.; Andjelic, M. M.; Pavlovic, M. Z. [Department of Astronomy, Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade (Serbia); Vukotic, B., E-mail: arbo@math.rs [Astronomical Observatory, Volgina 7, 11060 Belgrade (Serbia)

2012-02-10

142

MODIFIED EQUIPARTITION CALCULATION FOR SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

Determination of the magnetic field strength in the interstellar medium is one of the more 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 the Zeeman effect and Faraday rotation, the equipartition or 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 its approximate character, it remains a useful tool, especially when there are no other data about the magnetic field in a source. In this paper, we give a modified calculation that we think is more appropriate for estimating magnetic field strengths and energetics in supernova remnants (SNRs). 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 magnetic field strengths of SNRs is available at http://poincare.matf.bg.ac.rs/?arbo/eqp/.

143

X-ray imaging of supernova remnants and neutron stars - can we distinguish Type I remnants  

International Nuclear Information System (INIS)

The possibility of using X-ray imaging data to differentiate between Type I and Type II supernovae and to detect neutron stars in Type I remnants is considered. Based on an examination of Einstein Observatory X-ray images of supernova remnants, it is pointed out that, with the exceptions of Cas A and the Crab-like remnants, the structure of the interstellar medium dominates the X-ray emissivity of a remnent from early in its life. Imaging observations may, however, provide evidence for the type of event that created the remnant by allowing the estimation of the amount of ejecta thrown off in the explosion. X-ray observations have also been used to provide upper limits to the thermal emission from possible neutron stars in the five non-Crab-like historical remnants, which may indicate the lack of such objects and thereby impose constraints on the supernova model

144

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

145

Fermi-LAT Observations of Supernova Remnant Kesteven 79  

CERN Document Server

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

146

Multi-dimensional Simulations of the Expanding Supernova Remnant of SN 1987A  

Science.gov (United States)

The expanding remnant from SN 1987A is an excellent laboratory for investigating the physics of supernovae explosions. There is still a large number of outstanding questions, such as the reason for the asymmetric radio morphology, the structure of the pre-supernova environment, and the efficiency of particle acceleration at the supernova shock. We explore these questions using three-dimensional simulations of the expanding remnant between days 820 and 10,000 after the supernova. We combine a hydrodynamical simulation with semi-analytic treatments of diffusive shock acceleration and magnetic field amplification to derive radio emission as part of an inverse problem. Simulations show that an asymmetric explosion, combined with magnetic field amplification at the expanding shock, is able to replicate the persistent one-sided radio morphology of the remnant. We use an asymmetric Truelove & McKee progenitor with an envelope mass of 10 M ? and an energy of 1.5 × 1044 J. A termination shock in the progenitor's stellar wind at a distance of 0.''43-0.''51 provides a good fit to the turn on of radio emission around day 1200. For the H II region, a minimum distance of 0.''63 ± 0.''01 and maximum particle number density of (7.11 ± 1.78) × 107 m–3 produces a good fit to the evolving average radius and velocity of the expanding shocks from day 2000 to day 7000 after explosion. The model predicts a noticeable reduction, and possibly a temporary reversal, in the asymmetric radio morphology of the remnant after day 7000, when the forward shock left the eastern lobe of the equatorial ring.

Potter, T. M.; Staveley-Smith, L.; Reville, B.; Ng, C.-Y.; Bicknell, G. V.; Sutherland, R. S.; Wagner, A. Y.

2014-10-01

147

IS THERE A HIDDEN HOLE IN TYPE Ia SUPERNOVA REMNANTS?  

Energy Technology Data Exchange (ETDEWEB)

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.

Garcia-Senz, D. [Departament de Fisica i Enginyeria Nuclear, UPC, Compte d' Urgell 187, 08036 Barcelona (Spain); Badenes, C. [School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Serichol, N., E-mail: domingo.garcia@upc.edu, E-mail: carles@astro.tau.ac.il, E-mail: nuria.serichol@upc.edu [Departament de Matematica Aplicada III, Sor Eulalia d' Anzizu, 08034 Barcelona (Spain)

2012-01-20

148

Acceleration of cosmic rays in supernova-remnants  

International Nuclear Information System (INIS)

It is commonly accepted that supernova-explosions are the dominant source of cosmic rays up to an energy of 10 to the 14th power eV/nucleon. Moreover, these high energy particles provide a major contribution to the energy density of the interstellar medium (ISM) and should therefore be included in calcuations of interstellar dynamic phenomena. For the following the first order Fermi mechanism in shock waves are considered to be the main acceleration mechanism. The influence of this process is twofold; first, if the process is efficient (and in fact this is the case) it will modify the dynamics and evolution of a supernova-remnant (SNR), and secondly, the existence of a significant high energy component changes the overall picture of the ISM. The complexity of the underlying physics prevented detailed investigations of the full non-linear selfconsistent problem. For example, in the context of the energy balance of the ISM it has not been investigated how much energy of a SN-explosion can be transfered to cosmic rays in a time-dependent selfconsistent model. Nevertheless, a lot of progress was made on many aspects of the acceleration mechnism

149

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

International Nuclear Information System (INIS)

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

150

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

151

DISCOVERY OF X-RAY EMISSION FROM SUPERNOVA 1970G WITH CHANDRA: FILLING THE VOID BETWEEN SUPERNOVAE AND SUPERNOVA REMNANTS  

Science.gov (United States)

We report the discovery of X-ray emission from SN 1970G in M101, 35 yr after its outburst, using deep X-ray imaging with the Chundra X-Ray Observatory. The Chandra ACIS spectrum shows that the emission is soft (52 keV) and characteristic of the reverse-shock region. The X-ray luminosity, Lo,,, = (1.1 3 0.2) x lo3# ergs s-1, is likely caused by the interaction of the supernova shock with dense circumstellar matter. If the material was deposited by the stellar wind from the progenitor, a mass-loss rate of M = (2.6 ? 0.4) x M, yr-I (v,/lO km s-I) is inferred. Utilizing the high-resolution Chandra ACIS data of SN 1970G and its environment, we reconstruct the X-ray lightcurve from previous ROSAT HRI, PSPC, and XMM-Newton EPIC observations, and find a best-fit linear rate of decline of L cc t-# with index s = 2.7 t 0.9 over a period of -20-35 yr after the outburst. As the oldest supernova detected in X-rays, SN 1970G allows, for the first time, direct observation of the transition from a supenova to its supernova remnant phase.

Immler, Stefan; Kuntz, K. D.

2005-01-01

152

PHYSICAL STRUCTURE AND NATURE OF SUPERNOVA REMNANTS IN M101  

International Nuclear Information System (INIS)

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

153

In my Beginning is my End: Dust Destruction in the Cassiopeia A Supernova Remnant  

Science.gov (United States)

It has been demonstrated by observations that young supernovae (SNe) are indeed able to efficiently synthesize dust. However, it is unclear how much of the freshly formed dust can reach the interstellar medium and contribute to the observed emission. At the same time, SNe represent the major agent responsible for dust destruction. Because SNe are possibly the only viable dust factory in the early Universe, it is extremely important to establish the fate of the newly formed dust. Our work explores the possibility that a significant fraction of any dust formed after the explosion is destroyed within the supernova remnant itself. In the Cassiopeia A supernova remnant, dust emission has been observed associated with optical knots containing recently formed material. The dust present in such clumps is threatened by the reverse shock traveling through the ejecta toward the center of the remnant. The shock is able to disrupt the clumps and will inject the dust grains into a hot gas, where they will be eroded and possibly destroyed by thermal and inertial sputtering. We present a model that describes the propagation of the reverse shock into the supernova cavity and evaluates the modifications in the grain size distribution due to the encounter with the reverse shock. This is the first step required to quantify the amount of dust ultimately able to survive. Our model accounts for the variation of the physical properties of both the shock and the ejecta across the remnant. In particular, this means taking explicitly into consideration, for the first time in this kind of studies, the effect of clumping of the ejecta.

Micelotta, E.; Dwek, E.

154

Supernova remnant W49B and its environment  

CERN Document Server

We study Gamma-ray supernova remnant W49B and its environment using recent radio and infrared data. {\\it Spitzer} IRS low resolution data of W49B shows shocked excitation lines of H$_{2}$ (0,0) S(0)-S(7) from the SNR-molecular cloud interaction. The H$_2$ gas is composed of two components with temperature of $\\sim$260 K and $\\sim$1060 K respectively. Various spectral lines from atomic and ionic particles are detected towards W49B. We suggest the ionic phase has an electron density of $\\sim$500 cm${}^{-3}$ and a temperature of $\\sim$${10^4}$ K by the spectral line diagnoses. The mid- and far-infrared data from {\\it MSX}, {\\it Spitzer} and {\\it Herschel} reveals a 151 $\\pm$ 20 K hot dust component with a mass of 7.5 $\\pm$ 6.6 $\\times$ ${10}^{-4} {\\Msol}$ and a 45 $\\pm$ 4 K warm dust component with a mass of 6.4 $\\pm$ 3.2 ${\\Msol}$. The hot dust is likely from materials swept up by the shock of W49B. The warm dust may possibly originate from the evaporation of clouds interacting with W49B. We build the HI absorp...

Zhu, H; Zuo, P

2014-01-01

155

Slow Diffusion of Cosmic-Rays around a Supernova Remnant  

CERN Document Server

We study the escape of cosmic-ray protons accelerated at a supernova remnant (SNR). We are interested in their propagation in interstellar medium (ISM) after they leave the shock neighborhood where they are accelerated, but when they are still near the SNR with their energy density higher than that in the average ISM. Using Monte-Carlo simulations, we found that the cosmic-rays with energies of <~TeV excite Alfven waves around the SNR on a scale of the SNR itself if the ISM is highly ionized. Thus, even if the cosmic-rays can leave the shock, scattering by the waves prevents them from moving further away from the SNR. The cosmic-rays form a slowly expanding cosmic-ray bubble, and they spend a long time around the SNR. This means that the cosmic-rays cannot actually escape from the SNR until a fairly late stage of the SNR evolution. This is consistent with some results of Fermi and H.E.S.S. observations.

Fujita, Yutaka; Takahara, Fumio

2010-01-01

156

Interactions Between CRs and MCs in the Vicinity of Supernova Remnants  

Science.gov (United States)

Supernovae are incredibly energetic events which drive the dynamic state of the interstellar medium and accelerate cosmic rays up to energies of a few PeV. I present multi-wavelength observations constraining the shocks, chemistry, dust grain processing, and magnetic fields in a large sample of supernova remnants interacting with dense clouds. These are among the most luminous Galactic sources detected by the Fermi Gamma-Ray Space Telescope. Surprisingly, spectral breaks are seen between GeV and TeV energies. Radio spectral breaks have also been detected for a few remnants, providing clear evidence that supernovae are a significant source of hadronic cosmic rays in the Galaxy. Resolving the origin of these spectral breaks will allow the physics of cosmic ray acceleration and diffusion to be probed.

Hewitt, John W.

2011-01-01

157

Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant  

CERN Document Server

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

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

2007-01-01

158

Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant  

Science.gov (United States)

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, although too weak to be mapped over the whole remnant, is shown to vary radially. The line intensity peaks at about half the radius and drops at the edge of the remnant. Both the clumpy distribution of C IV and the rise in the C IV to C III ratio toward the edge suggest that central emission is from evaporating cloudlets rather than thermal conduction in a more uniform, dense medium.

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.

2007-12-01

159

Radio observations of small diameter sources in the direction of old supernova remnants  

International Nuclear Information System (INIS)

Radio observations with high sensitivity have shown that lots of more or less compact structures can be found in the field of extended and old supernova remnants (SNRs). These small diameter sources have been subject to many recent observations. The aim of these studies is to infer a possible physical association of these sources with the SNR shell. The interest in this link is based on various aspects, instabilities of shocked interstellar matter, star formation, etc. (Auth.)

160

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

International Nuclear Information System (INIS)

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

 
 
 
 
161

On the origin of strong magnetic fields in young supernova remnants  

CERN Document Server

Young supernova remnants such as Tycho generally exhibit a bright circular clumpy shell in both radio and X-ray emission. For several young remnants, various arguments suggest that the magnetic field is larger than can be explained by compression of a few \\mu G ambient magnetic field by the shock wave. Radio polarization studies reveal a net radial orientation of magnetic fields in the shell which cannot be explained by the simple compression either. We model Rayleigh-Taylor instability at the interface of the ejecta and the shocked ambient medium to explain these observations. We have performed multidimensional MHD simulations of the instability in the shell of a Type-I supernova remnant for the first time utilizing a moving grid technique which allows us to follow the growth of the instability and its effect on the local magnetic field in detail. We find that the evolution of the instability is very sensitive to the deceleration of the ejecta and the evolutionary stage of the remnant. As the reverse shock e...

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

1996-01-01

162

Study of the extended radio emission of two supernova remnants and four planetary nebulae associated to MIPSGAL bubbles  

CERN Document Server

We present radio observations of two supernova remnants and four planetary nebulae with the Very Large Array and the Green Bank Telescope. These objects are part of a larger sample of radio sources, discussed in a previous paper, counterpart of the MIPSGAL 24-micron compact bubbles. For the two supernova remnants we combined the interferometric observations with single-dish data to obtain both a high resolution and a good sensitivity to extended structures. We discuss in detail the entire combination procedure adopted and the reliability of the resulting maps. For one supernova remnant we pose a more stringent upper limit for the flux density of its undetected pulsar, and we also show prominent spectral index spatial variations, probably due to inhomogeneities in the magnetic field and in its ejecta or to an interaction between the supernova shock and molecular clouds. We eventually use the 5-GHz maps of the four planetary nebulae to estimate their distance and their ionized mass.

Ingallinera, Adriano; Umana, Grazia; Leto, Paolo; Agliozzo, Claudia; Buemi, Carla

2014-01-01

163

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.

164

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

165

Revealing the Supernova Remnant Population of M33 with Chandra  

CERN Document Server

We present results of a search for supernova remnants (SNRs) in archival Chandra images of M33. We have identified X-ray SNRs by comparing the list of Chandra, X-ray sources in M33 with tabulations of SNR candidates identified from (1) elevated [S II]/Halpha ratios in the optical, and (2) radio spectral indices. Of the 98 optically known SNRs in M33, 22 have been detected at > 3-sigma level in the soft band (0.35-1.1 keV). At least four of these SNR candidates are spatially extended based on a comparison of the data to simulated images of point sources. Aside from the optically matching SNRs, we have found one soft X-ray source in M33 which exhibits no optical emission and is coincident with a known radio source. The radio spectral index of this source is consistent with particle acceleration in shocks, leading us to suggest that it is a non-radiative SNR. We have also found new optical counterparts to two soft X-ray SNRs in M33. Pending confirmation from optical spectroscopy, the identification of these two ...

Ghavamian, P; Long, K S; Sasaki, M; Gaetz, T J; Plucinsky, P P; Ghavamian, Parviz; Blair, William P.; Long, Knox S.; Sasaki, Manami; Gaetz, Terrance J.; Plucinsky, Paul P.

2005-01-01

166

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

Science.gov (United States)

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

Badenes, Carles

2010-04-20

167

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

168

10^51 Ergs: The Evolution of Shell Supernova Remnants  

Science.gov (United States)

This paper reports on the workshop ``10^51 Ergs: The Evolution of Shell Supernova Remnants,'' hosted by the University of Minnesota, 1997 March 23-26. The workshop was designed to address fundamental dynamical issues associated with the evolution of shell supernova remnants and to understand better the relationships between supernova remnants and their environments. Although the title points only to classical, shell SNR structures, the workshop also considered dynamical issues involving X-ray-filled composite remnants and pulsar-driven shells, such as that in the Crab Nebula. Approximately 75 observers, theorists, and numerical simulators with wide-ranging interests attended the workshop. An even larger community helped through extensive on-line debates prior to the meeting to focus issues and galvanize discussion. In order to deflect thinking away from traditional patterns, the workshop was organized around chronological sessions for ``very young,'' ``young,'' ``mature,'' and ``old'' remnants, with the implicit recognition that these labels are often difficult to apply. Special sessions were devoted to related issues in plerions and ``thermal X-ray composites.'' Controversy and debate were encouraged. Each session also addressed some underlying, general physical themes: How are supernova remnant (SNR) dynamics and structures modified by the character of the circumstellar medium (CSM) and the interstellar medium (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 presence influence or reveal SNR dynamics? How does SNR blast energy partition into various components over time, and what controls conversion between components? In lieu of a proceedings volume, we present here a synopsis of the workshop in the form of brief summaries of the workshop sessions. The sharpest impressions from the workshop were the crucial and underappreciated roles that environments have on SNR appearance and dynamics and the critical need for broad-based studies to understand these beautiful but enigmatic objects.

Jones, T. W.; Rudnick, Lawrence; Jun, Byung-Il; Borkowski, Kazimierz J.; Dubner, Gloria; Frail, Dale A.; Kang, Hyesung; Kassim, Namir E.; McCray, Richard

1998-02-01

169

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

170

Properties of Optically Selected Supernova Remnant Candidates in M33  

Science.gov (United States)

Narrowband images covering strong emission lines are efficient for surveying supernova remnants (SNRs) in nearby galaxies. Using the narrowband images provided by the Local Group Galaxy Survey, we searched for SNRs in M33. Culling the objects with enhanced [S II]/H? and round morphology in the continuum-subtracted H? and [S II] images, we produced a list of 199 sources. Among them, 79 are previously unknown. Their progenitor and morphology types were classified. A majority of the sample (170 objects) are likely remnants of core-collapse supernovae (SNe), and 29 are remnants of Type Ia SNe. The cumulative size distribution of these objects is found to be similar to that of the M31 remnants derived in a similar way. We obtain a power-law slope, ? = 2.38 ± 0.05. Thus, a majority of the sources are considered to be in the Sedov-Taylor phase, consistent with previous findings. The histogram of the emission-line ratio ([S II]/H?) of the remnants has two concentrations at [S II]/H? ~ 0.55 and ~0.8, as in M31. Interestingly, L X (and L 20 cm) of the compact center-bright objects are correlated with their optical luminosity. The remnants with X-ray emission have brighter optical surface brightnesses and smaller diameters than those without X-ray emission.

Lee, Jong Hwan; Lee, Myung Gyoon

2014-10-01

171

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

172

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

173

Oxygen emission in remnants of thermonuclear supernovae as a probe for their progenitor system  

CERN Document Server

Recent progress in numerical simulations of thermonuclear supernova explosions brings up a unique opportunity in studying the progenitors of Type Ia supernovae. Coupling state-of-the-art explosion models with detailed hydrodynamical simulations of the supernova remnant evolution and the most up-to-date atomic data for X-ray emission calculations makes it possible to create realistic synthetic X-ray spectra for the supernova remnant phase. Comparing such spectra with high quality observations of supernova remnants could allow to constrain the explosion mechanism and the progenitor of the supernova. The present study focuses in particular on the oxygen emission line properties in young supernova remnants, since different explosion scenarios predict a different amount and distribution of this element. Analysis of the soft X-ray spectra from supernova remnants in the Large Magellanic Cloud and confrontation with remnant models for different explosion scenarios suggests that SNR 0509-67.5 could originate from a de...

Kosenko, D; Kromer, M; Blinnikov, S I; Pakmor, R; Kaastra, J S

2014-01-01

174

Small-scale structure in young supernova remnants  

International Nuclear Information System (INIS)

Recent VLA observations of the shell supernova remnant SN 1006 AD and the Crablike remnant 3C 58 (SN 1181 AD?; Reynolds and Aller 1987) show features at high resolution that contain information on details of particle acceleration and transport in the remnants. Thin arcs at the edge of SN 1006 require time-variable particle acceleration and/or magnetic field amplification. Filaments in 3C 58 probably result from interaction of pulsar-generated relativistic fluid with filaments of thermal gas formed early in the remnant's life by cooling or dynamical instabilities. Their sharp edges imply efficient scattering by Alfven waves; as much as 1% of the large-scale magnetic energy density may be in magnetic turbulence on length scales of 1011 cm

175

3D Simulations of Supernova Remnants from Type Ia Supernova Models  

Science.gov (United States)

Type Ia supernovae (SNe) originate from thermonuclear explosions of white dwarfs. A great deal is still unknown about the explosion mechanisms, particularly the degree of asymmetry. However, Type Ia supernova remnants (SNRs) can bear the imprint of asymmetry long after the explosion. A SNR of interest is G1.9+0.3, the youngest Galactic SNR, which demonstrates an unusual spatial distribution of elements in the ejecta. While its X-ray spectrum is dominated by synchrotron emission, spectral lines of highly ionized Si, S, and Fe are seen in a few locations, with Fe near the edge of the remnant and with strongly varying Fe/Si ratios. An asymmetric explosion within the white dwarf progenitor may be necessary to explain these unusual features of G1.9+0.3, in particular the shocked Fe at large radii. We use the VH-1 hydrodynamics code to evolve initial Type Ia explosion models in 1, 2, and 3 dimensions at an age of 100 seconds provided by other researchers to study asymmetry, the ignition properties, and the nucleosynthesis resulting from these explosions. We follow the evolution of these models interacting with a uniform external medium to a few hundred years in age. We find the abundance and location of ejecta elements from our models to be inconsistent with the observations of G1.9+0.3; while our models show asymmetric element distributions, we find no tendency for iron-group elements to be found beyond intermediate-mass elements, or for significant iron to be reverse-shocked at all at the age of G1.9+0.3. We compare the amounts of shocked iron-group and intermediate-mass elements as a function of time in the different models. Some new kind of explosion asymmetry may be required to explain G1.9+0.3. This work was performed as part of NC State University's Undergraduate Research in Computational Astrophysics (URCA) program, an REU program supported by the National Science Foundation through award AST-1032736.

Johnson, Heather; Reynolds, S. P.; Frohlich, C.; Blondin, J. M.

2014-01-01

176

Are young supernova remnants interacting with circumstellar gas  

International Nuclear Information System (INIS)

The young remnants of galactic Type I supernovae (SN 1006, SN 1572, and SN 1604) appear to be interacting with moderately dense gas (n/sub O/> or =0.1 cm-3). If the gas in the ambient interstellar medium, the observations suggest that gas of this density is fairly pervasive. If the gas is circumstellar, there are important implications for the progenitors of Type I supernovae. A plausible density distribution for circumstellar gas is rhoinfinityr-2. The expansion of a supernova into such a medium is examined and is compared with expansion into a uniform medium. The two cases can be distinguished on the basis of their density profiles and their rates of expansion. Currently available data factor the hypothesis of expansion in a uniform medium for all three Type I remnants; the evidence is the strongest for SN 1572 and the weakest for SN 1604. Further X-ray and radio observations of the galactic remnants and of extragalactic Type I supernovae should serve to test this hypothesis

177

Hydrodynamics of Young Supernova Remnants and the Implications for their Gamma-ray emission  

CERN Document Server

Supernovae (SNe) are generally classified into Type I and Type II. Most SNe (~ 80%), including all the subtypes of Type II, and Type Ib/c, arise from the core-collapse of massive stars. During their lifetime, mass-loss from these stars considerably modifies the medium around the stars. When the stars explode as SNe, the resulting shock wave will expand in this wind-modified medium. In contrast, Type Ia SNe will expand in a relatively uniform medium, but the dynamics are different from those of core-collapse SNe. For young supernova remnants, the properties of the ejecta as well as the surrounding medium are important in determining the subsequent evolution of the SN shock wave, and the dynamics and kinematics of the remnant. This will influence the acceleration of particles at the SN shocks, and consequently affect the gamma-ray emission from the remnant. Herein we discuss the expected properties, especially the density structure, of the medium around various types and sub-types of SNe, as suggested by curren...

Dwarkadas, Vikram

2014-01-01

178

Validating the Supernova Remnant Hypothesis of the Cosmic Ray Origin  

Science.gov (United States)

The century-old problem of the origin and acceleration of cosmic rays (CR) could soon be resolved. However, as it is impossible to trace CR back to their accelerators because of orbit scrambling in the galactic magnetic field, the solution will not be easy. Also the direct observations of a secondary gamma emission from supernova remnant (SNR) shocks, long suspected to be the main source of galactic CRs, are complicated by the contaminating electron emission. Therefore, the SNR hypothesis of the CR origin can be proven beyond a reasonable doubt only if the acceleration theory is fully consistent with the observations. However, the complexity of plasma dynamics in SNR shocks makes the validation of the SNR hypothesis very difficult. A study of the crucial plasma processes in SNR shocks is proposed. It will determine the three-way partitioning of the shock energy between accelerated particles (protons and electrons), turbulent magnetic fields and thermal plasma. The project includes a comparative analysis of three instabilities, arguably crucial to the diffusive shock acceleration (DSA) mechanism: i.) the cyclotron resonance CR instability, ii.) the non- resonant CR-current driven (kink-type) instability and iii.) the acoustic CR-pressure gradient driven instability. By identifying the dominant instability depending on the local SNR environment, the spectra of different species of accelerated particles, their losses, and the broadband radiation will be calculated and compared to both direct observations of the secondary emission from major SNRs and to the measurements of the background CRs. The comparison will show whether the DSA mechanism production of CR in SNR is consistent with the observed emission. The remnants most visible in gamma rays expand into weakly ionized, dense gases. The physics of the CR production in such environments based on the three instabilities will be studied. The proposer's previous work has shown that the propagation of CRs in a dense SNR surrounding should result in a break in the particle and gamma-ray emission spectra, now frequently observed in such SNRs. The theoretical studies and modeling of the breaks, resulting from interactions of CR with a self-driven wave turbulence, will be carried out for conditions relevant to the observed SNRs. The problem of disentangling electron and proton emissions will be addressed. To this end, a new mechanism of electron injection into the DSA will be examined. This mechanism is based on a macroscopic electric field generated by the current-driven turbulence and penetration of CR into weakly ionized gas upstream. The electric field can accelerate electrons, leading to runaway. This process is well known from laboratory plasma research, so the proposer’s expertise in magnetic confinement studies will be utilized. The escape of accelerated particles into the SNR surroundings are studied separately from this proposal and may also become useful for the purpose of electron/proton differentiation. This will be based, in particular but not exclusively, on the fact that the proton high energy emission pattern is correlated with the ambient dense gas distribution, as opposed to the inverse Compton electron emission. CRs play a fundamental role in our understanding of the structure and evolution of the universe and the mystery of their origin is longstanding and difficult to solve. Very recent revolutionary improvements in SNR observations and CR measurements, including such NASA missions as Fermi and Chandra offer a unique chance for a theoretical breakthrough in validating the SNR hypothesis of the origin of galactic CRs. The proposers will be able to analytically predict CR spectral features, such as breaks and spectral slope variations among different elements. As these features are unique to the DSA, their comparison with the data will help to determine whether the DSA mechanism is indeed responsible for the production of galactic CR in SNRs.

Malkov, Mikhail

179

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

180

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

 
 
 
 
181

Neutron Stars in Supernovae and Their Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The magnetic fields of neutron stars have a large range (~3e10 - 1e15 G). There may be a tendency for more highly magnetized neutron stars to come from more massive stellar progenitors, but other factors must also play a role. When combined with the likely initial periods of neutron stars, the magnetic fields imply a spindown power that covers a large range and is typically dominated by other power sources in supernovae. Distinctive features of power input from pulsar spindo...

Chevalier, Roger A.

2010-01-01

182

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

183

Understanding hadronic gamma-ray emission from supernova remnants  

International Nuclear Information System (INIS)

We aim to test the plausibility of a theoretical framework in which the gamma-ray emission detected from supernova remnants may be of hadronic origin, i.e., due to the decay of neutral pions produced in nuclear collisions involving relativistic nuclei. In particular, we investigate the effects induced by magnetic field amplification on the expected particle spectra, outlining a phenomenological scenario consistent with both the underlying Physics and the larger and larger amount of observational data provided by the present generation of gamma experiments, which seem to indicate rather steep spectra for the accelerated particles. In addition, in order to study to study how pre-supernova winds might affect the expected emission in this class of sources, the time-dependent gamma-ray luminosity of a remnant with a massive progenitor is worked out. Solid points and limitations of the proposed scenario are finally discussed in a critical way

184

Planck intermediate results. XXXI. Microwave survey of Galactic supernova remnants  

CERN Document Server

The all-sky Planck survey in 9 frequency bands was used to search for emission from all 274 known Galactic supernova remnants. Of these, 17 were detected in at least two Planck frequencies. The radio-through-microwave spectral energy distributions were compiled to determine the emission mechanism for microwave emission. In only one case, IC 443, is the high-frequency emission clearly from dust associated with the supernova remnant. In all cases, the low-frequency emission is from synchrotron radiation. A single power law, as predicted for a population of relativistic particles with energy distribution that extends continuously to high energies, is evident for many sources, including the Crab and PKS 1209-51/52. A decrease in flux density relative to the extrapolation of radio emission is evident in several sources. Their spectral energy distributions can be approximated as broken power laws, $S_\

,

2014-01-01

185

Escape of cosmic-ray electrons from supernova remnants  

Science.gov (United States)

We investigate the escape of cosmic ray (CR) electrons from a supernova remnant (SNR) to interstellar space. We show that CR electrons escape in order, from high energies to low energies, like CR nuclei. However, the escape starts later than the beginning of the Sedov phase at an SNR age of 103 to 7 × 103 yr, and the maximum energy of runaway CR electrons is below the knee at about 0.3-50 TeV because, unlike CR nuclei, CR electrons lose their energy as a result of synchrotron radiation. The highest-energy CR electrons might have already been detected by the High Energy Stereoscopic System (HESS) and MAGIC as a cut-off in the CR electron spectrum, and it will be probed by the Alpha Magnetic Spectrometer (AMS-02), the Calorimeteric Electron Telescope (CALET), the Cherenkov Telescope Array (CTA) and the Large High Altitude Air Shower Observatory (LHAASO) experiments. We also calculate the spatial distribution of runaway CR electrons and their radiation spectra around SNRs. Contrary to common belief, maximum-energy photons of synchrotron radiation around 1 keV are emitted by runaway CR electrons, which have been caught up by the shock. Inverse Compton scattering by runaway CR electrons can dominate the gamma-ray emission from runaway CR nuclei via pion decay. Both are detectable by CTA and LHAASO and they can give clues to the origin of CRs and the amplification of magnetic fluctuations around the SNR. We also discuss middle-aged and/or old SNRs as unidentified very-high-energy gamma-ray sources.

Ohira, Yutaka; Yamazaki, Ryo; Kawanaka, Norita; Ioka, Kunihito

2012-11-01

186

Acceleration of cosmic rays by young core-collapse supernova remnants  

CERN Document Server

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

Telezhinsky, I; Pohl, M

2012-01-01

187

Understanding hadronic gamma-ray emission from supernova remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We aim to test the plausibility of a theoretical framework in which the gamma-ray emission detected from supernova remnants may be of hadronic origin, i.e., due to the decay of neutral pions produced in nuclear collisions involving relativistic nuclei. In particular, we investigate the effects induced by magnetic field amplification on the expected particle spectra, outlining a phenomenological scenario consistent with both the underlying Physics and the larger and larger am...

Caprioli, Damiano

2011-01-01

188

THE 7Li/6Li ISOTOPE RATIO NEAR THE SUPERNOVA REMNANT IC 443  

International Nuclear Information System (INIS)

We present an analysis of 7Li/6Li isotope ratios along four sight lines that probe diffuse molecular gas near the supernova remnant IC 443. Recent gamma-ray observations have revealed the presence of shock-accelerated cosmic rays interacting with the molecular cloud surrounding the remnant. Our results indicate that the 7Li/6Li ratio is lower in regions more strongly affected by these interactions, a sign of recent Li production by cosmic rays. We find that 7Li/6Li ?7 toward HD 254755, which is located just outside the visible edge of IC 443, while 7Li/6Li ?3 along the line of sight to HD 43582, which probes the interior region of the supernova remnant. No evidence of 7Li synthesis by neutrino-induced spallation is found in material presumably contaminated by the ejecta of a core-collapse supernova. The lack of a neutrino signature in the 7Li/6Li ratios near IC 443 is consistent with recent models of Galactic chemical evolution, which suggest that the ?-process plays only a minor role in Li production.

189

X-ray observations of the supernova remnant W44  

International Nuclear Information System (INIS)

Einstein Observatory X-ray observations of the supernova remnant W44(G34.7-0.4) are presented. The X-ray morphology is centrally peaked and shows an anti-correlation with the radio shell. X-ray spectral data indicate a temperature for the emitting plasma of approximately 1 keV. A model for W44 in which the remnant is in its late adiabatic phase is suggested. The soft X-ray shell has become too cool to be observable through the intervening ISM, yet a hotter interior remains visible. W44 would then appear to fit in reasonably well with the generally accepted evolution of shell-like remnants and a Crab-like component is not required to explain the X-ray morphology. (author)

190

Radio polarization observations of large supernova remnants at 6cm  

CERN Document Server

We have observed 79 supernova remnants (SNRs) with the Urumqi 25m telescope at 6cm during the Sino-German 6cm polarization survey of the Galactic plane. We measured flux densities of SNRs at 6cm, some of which are the first measurements or the data at highest frequencies, so that we can determine or improve spectra of SNRs. Our observations have ruled out the suggested spectral breaks or spectral flattening of a few SNRs, and confirmed the spectral break of S147. Combined our 6cm maps with 11cm and 21cm maps from the Effelsberg 100m telescope, we calculated the spectral index maps of several large SNRs. For many remnants, we obtained for the first time polarization images, which show the intrinsic magnetic field structures at 6 cm. We disapproved three "remnants", OA184, G192.8-1.1 and G16.8-1.1, which show a thermal spectrum and no polarization. We have discovered two large supernova remnant, G178.2-4.2 and G25.1-2.3, from the 6cm survey maps.

Han, J L; Sun, X H; Reich, W; Xiao, L; Reich, P; Xu, J W; Shi, W B; Fuerst, E; Wielebinski, R

2013-01-01

191

The Neutron Star Born in the Antlia Supernova Remnant  

CERN Document Server

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

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

2013-01-01

192

The Radio Structure of the Supernova Remnant MSH14-63  

CERN Document Server

G315.4-2.3 is an extended shell supernova remnant (SNR) with some characteristics of evolutionarily young remnants and some of older ones. To further elucidate some of its characteristics, we present imaging and polarimetry of this SNR at a frequency of 1.34 GHz with a resolution of 8 arcsec made with the Australia Telescope Compact Array. The indicators of youth are: Morphologically, the radio emission arises in a smooth shell without the fine scale filaments seen in the optical. Many of the optical filaments are Balmer dominated. Where measurable, the orientation of the magnetic field appears to be radial with respect to the center of the remnant. There may have been a supernova in that region in AD185. Indications of older age include: Particularly in RCW86, the bright optical nebula in the southwestern corner of this extended SNR, but also in other locations there are several filaments with bright [S II] emission representative of older shocked filaments in radiative equilibrium. If the remnant lies at th...

Dickel, J R; Milne, D K; dickel, John R.; Strom, Richard G.

2000-01-01

193

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

194

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.

195

Soft X-ray filter spectroscopy of the supernova remnants Vela X and Puppis A  

International Nuclear Information System (INIS)

In January 1977 the supernova remnants Vela X and Puppis A were observed in the soft X-ray region by a sounding rocket experiment consisting of 12 X-ray paraboloidal collectors. To improve the energy resolution of the proportional counter detectors, filter spectroscopy has been applied. Besides the temperature and interstellar column density, flux values for the dominant lines (O VII, O VIII, Ne IX, Fe XVII, and Fe XVIII) and corresponding abundances have been derived. Further intrinsic parameters of both SNR's could be deduced from a general shock wave model for SNR's. (orig.)

196

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

CERN Document Server

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

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

2013-01-01

197

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

198

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

International Nuclear Information System (INIS)

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

199

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

200

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

International Nuclear Information System (INIS)

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 ?-ray emission detected by Fermi shows that the emission may originate from the reverse shock-crushed PWN.

 
 
 
 
201

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

202

Radio polarization observations of large supernova remnants at ?6 cm  

Science.gov (United States)

We have observed 79 supernova remnants (SNRs) with the Urumqi 25 m telescope at ?6 cm during the Sino-German ?6 cm polarization survey of the Galactic plane. We measured flux densities of SNRs at ?6 cm, some of which are the first ever measured or the measurements at the highest frequency, so that we can determine or improve spectra of SNRs. Our observations have ruled out spectral breaks or spectral flattening that were suggested for a few SNRs, and confirmed the spectral break of S147. By combining our ?6 cm maps with ?11 cm and ?21 cm maps from the Effelsberg 100 m telescope, we calculated the spectral index maps of several large SNRs. For many remnants we obtained for the first time polarization images, which show the intrinsic magnetic field structures at ?6 cm. We disapproved three objects as being SNRs, OA184, G192.8-1.1 and G16.8-1.1, which show a thermal spectrum and no polarization. We have discovered two large supernova remnants, G178.2-4.2 and G25.1-2.3., in the survey maps.

Han, J. L.; Gao, X. Y.; Sun, X. H.; Reich, W.; Xiao, L.; Reich, P.; Xu, J. W.; Shi, W. B.; Fürst, E.; Wielebinski, R.

2014-01-01

203

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

204

Interaction Between Supernova Remnant G22.7-0.2 And The Ambient Molecular Clouds  

CERN Document Server

We have carried out 12CO (J=1-0 and 2-1), 13CO (J=1-0), and C18O (J=1-0) observations in the direction of the supernova remnant (SNR) G22.7-0.2. A filamentary molecular gas structure, which is likely part of a larger molecular complex with VLSR~75-79 km/s, is detected and is found to surround the southern boundary of the remnant. In particular, the high-velocity wing (77-110 km/s) in the 12CO (J=1-0 and J=2-1) emission shows convincing evidence of the interaction between SNR G22.7-0.2 and the 75-79 km/s molecular clouds (MCs). Spectra with redshifted profiles, a signature of shocked molecular gas, are seen in the southeastern boundary of the remnant. The association between the remnant and the 77 km/s MCs places the remnant at the near distance of 4.0-4.8 kpc, which agrees with a location on the Scutum-Crux arm. We suggest that SNR G22.7-0.2, SNR W41, and HII region G022.760-0.485 are at the same distance and are associated with GMC G23.0-0.4.

Su, Yang; Zhou, Xin; Zhou, Ping; Chen, Yang

2014-01-01

205

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

Science.gov (United States)

We present new Australia Telescope Compact Array radio-continuum and XMM-Newton/Chandra X-ray Observatory observations of the unusual supernova remnant (SNR) HFPK 334 in the Small Magellanic Cloud (SMC). The remnant follows a shell-type morphology in the radio continuum and has a size of ~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 power law with a photon index of ? = 2.7 ± 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 points toward a younger SNR with an age of <~ 1800 yr. With an average radio spectral index of ? = –0.59 ± 0.09, we find that an equipartition magnetic field for the remnant is ~90 ?G, a value typical of younger SNRs in low-density environments. Also, we report the detection of scattered radio polarization across the remnant at 20 cm, with a peak fractional polarization level of 25% ± 5%.

Crawford, E. J.; Filipovi?, M. D.; McEntaffer, R. L.; Brantseg, T.; Heitritter, K.; Roper, Q.; Haberl, F.; Uroševi?, D.

2014-11-01

206

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

CERN Document Server

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 micron 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 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 mat...

Sankrit, R; Bautista, M; Gaetz, T J; Williams, B J; Blair, W P; Borkowski, K J; Long, K S

2014-01-01

207

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

CERN Document Server

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

208

An Evaluation of the Richtmyer-Meshkov Instability in Supernova Remnant Formation  

International Nuclear Information System (INIS)

We present an initial evaluation of the role of the Richtmyer-Meshkov (RM) instability in supernova remnant (SNR) formation. Although the Rayleigh-Taylor (RT) instability is most often considered in the canonical picture of SNR formation, the theoretical penetration depths for RM instability suggest that it could play a significant role in the early stages of SNR formation. We have used the code PROMETHEUS to perform a sequence of two-dimensional hydrodynamic simulations in order to test this possibility. Here we discuss a case in which we impose a large perturbation in the expanding ejecta behind the reverse shock. The interaction of the reverse shock with the perturbation produces significant early RM growth, with spikes penetrating from the contact surface to near the forward shock. Then the RM instability weakens, RT growth eventually dominates, and the perturbation of the forward shock diminishes. We conclude that RM instability growth due to the type of perturbation we have studied might contribute to, but alone cannot account for, the observed radio and X-ray structures that extend to the forward shock in such SNRs as supernova 1006. copyright copyright 1999. The American Astronomical Society

209

Discovery of a Pre-existing Molecular Filament Associated with Supernova Remnant G127.1+0.5  

Science.gov (United States)

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. We argue that the curved part of the filament is fully engulfed by the remnant's forward shock. A spatial correlation between aggregated young stellar objects (YSOs) and the adjacent molecular filament close to the SNR is also found, which could be related to the progenitor's activity.

Zhou, Xin; Yang, Ji; Fang, Min; Su, Yang

2014-08-01

210

RADIO EMISSION FROM YOUNG SUPERNOVAE AND SUPERNOVA REMNANTS IN Arp 299  

International Nuclear Information System (INIS)

We have made sensitive milliarcsecond-resolution radio images of the nearby merger galaxy Arp 299 at four epochs spread over 18 months between 2003 and 2005. The combined data revealed a total of 30 point sources in the two primary merger nuclei. Twenty-five of these are found in the northeastern nucleus (component 'A' = IC 694) over a region ?100 pc in diameter, while five are in the southwestern nucleus (component 'B1' = NGC 3690) within a region ?30 pc in size. These objects are interpreted as young supernovae and supernova remnants; the ratio of the source counts in nuclei A and B1 is approximately equal to the ratio of their predicted supernova rates. An approximate luminosity function has been derived for nucleus A, and indicates that it might contain as many as 500-1000 compact radio sources more powerful than Cassiopeia A; the integrated flux density of these sources would be about 20% of the total flux density seen at lower resolution. A new supernova occurred in nucleus B1 in the first half of 2005, having a peak radio power at least 2000 times the present power of Cas A. This supernova is located within 0.4 pc (projected distance) of an apparently older supernova remnant, making it very likely that this indicates the presence of a massive super star cluster within nucleus B1. Comparison of the typical radio flux densities of our compact radio sources to the observed X-ray luminosities of nuclei A and B1 indicates that it is possible that one radio sourcat it is possible that one radio source in each nucleus actually could be associated with an active galactic nucleus rather than being a supernova remnant.

211

X-ray Emission from the Galactic Supernova Remnant G272.2-3.2  

CERN Document Server

We present analysis of Chandra X-ray Observatory data detailing a galactic supernova remnant, G272.2-3.2. A clear shell of emission has been resolved for the first time 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. Spatially separated from this 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 8700 years for G272.2-3.2.

McEntaffer, Randall L; Brantseg, Thomas

2013-01-01

212

Soft x-ray observations of four supernova remnants  

International Nuclear Information System (INIS)

The study of four supernova remnants, SN1006, HB3, IC443 and 3C 58 is carried out using soft x-ray data (0.15-3.0 keV) acquired by the Low Energy Detectors of the A2 experiment on the x-ray astronomy satellite HEAO-A. Crude positional information and detailed spectra are obtained for each. Various models have been fitted to the spectral data in an attempt to elucidate the physical conditions within the remnant, and to determine the stage and the progress of its evolution. Estimates of the age, the initial blast energy and the density of the local interstellar medium have also been determined

213

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

International Nuclear Information System (INIS)

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

214

The Masses of M31 Supernova Remnant Progenitors  

Science.gov (United States)

We propose to expand our previous successful archival program to constrain the progenitor masses of supernova remnants {SNRs} in M31. Our previous program has resulted in 2 papers that each significantly improve our knowledge of the mass distribution of stars that produce supernovae. However, a new and significantly improved SNR catalog has been released this year, which is more comprehensive and reliable that anything available at the time of our previous program. The amount of high-quality HST imaging has also increased. This new catalog provides 106 SNRs with HST coverage, 67 of which were not measured by our previous archival program. Furthermore, our technique for measuring uncertainties in our mass estimates has become more reliable. This expanded and updated program will increase the number of measurements SNRs by a factor of 2, while also producing a much cleaner, more homogeneous sample.

Williams, Benjamin

2014-10-01

215

Shape of cooling filaments in old supernova remnants  

International Nuclear Information System (INIS)

The growth of density perturbations through thermal instabilities can account for filamentary features in old supernova remnants. Here, the cross sectional shape of a forming filament is calculated. As expected, the cross section of the filament flattens as it cools, and a feature degenerates into a thin sheet. The shape, however, is unstable to asymmetric warping disturbances. This probably leads to a number of parallel striations as the filament splits up, consistent with observations in the Cygnus Loop. The ratio of depth to width is typically 10:1, and so the feature may appear to be tubelike or a sheet, depending upon perspective

216

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

217

Structures of four supernova remnants at 1.4 GHz  

International Nuclear Information System (INIS)

Four small-diameter supernova remnants (SNRs) have been mapped with the Fleurs synthesis radio telescope; the maps are the first to reveal structure in these SNRs, all of which lie near zero declination, where most other synthesis telescopes do not provide satisfactory north-south resolution. Three of the sources (G15.9 + 0.2, G27.4 + 0.0 and G41.1 -0.3) show clear indications of a shell structure; the remaining source, G39.2 - 0.3, may be a rarer variety of SNR showing centrally concentrated emission similar to the Crab Nebula. (author)

218

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 103 km s-1. Redshifted Si/sup +,+2,+3/ lines at #betta#/sub r/approx.5 x 103 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

219

The Magellan/IMACS Catalog of Optical Supernova Remnant Candidates in M83  

CERN Document Server

We present a new optical imaging survey of supernova remnants in M83, using data obtained with the Magellan I 6.5m telescope and IMACS instrument under conditions of excellent seeing. Using the criterion of strong [S II] emission relative to Halpha, we confirm all but three of the 71 SNR candidates listed in our previous survey, and expand the SNR candidate list to 225 objects, more than tripling the earlier sample. Comparing the optical survey with a new deep X-ray survey of M83 with Chandra, we find 61 of these SNR candidates to have X-ray counterparts. We also identify an additional list of 46 [O III] -selected nebulae for follow-up as potential ejecta-dominated remnants, seven of which have associated X-ray emission that makes them strong candidates. Some of the other [O III]-bright objects could also be normal ISM-dominated supernova remnants with shocks fast enough to doubly ionize oxygen, but with Halpha and [S II] emission faint enough to have been missed. A few of these objects may also be H II regio...

Blair, William P; Long, K S

2012-01-01

220

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

 
 
 
 
221

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

222

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

223

Effect of stellar structure on supernova remnant evolution  

International Nuclear Information System (INIS)

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

224

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

225

SPITZER OBSERVATIONS OF DUST DESTRUCTION IN THE PUPPIS A SUPERNOVA REMNANT  

International Nuclear Information System (INIS)

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

226

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

227

POLYCYCLIC AROMATIC HYDROCARBON PROCESSING IN THE BLAST WAVE OF THE SUPERNOVA REMNANT N132D  

International Nuclear Information System (INIS)

We present Spitzer Infrared Spectrograph 14-36 ?m mapping observations of the supernova remnant N132D in the Large Magellanic Cloud. This study focuses on the processing of polycyclic aromatic hydrocarbons (PAHs) that we previously identified in the southern blast wave. The mid-infrared spectra show strong continuum emission from shock-heated dust and a unique, nearly featureless plateau in the 15-20 ?m region, which we attribute to PAH molecules. The typical PAH emission bands observed in the surrounding interstellar medium ahead of the blast wave disappear, which indicates shock processing of PAH molecules. The PAH plateau appears most strongly at the outer edge of the blast wave and coincides with diffuse X-ray emission that precedes the brightest X-ray and optical filaments. This suggests that PAH molecules in the surrounding medium are swept up and processed in the hot gas of the blast wave shock, where they survive the harsh conditions long enough to be detected. We also observe a broad emission feature at 20 ?m appearing with the PAH plateau. We speculate that this feature is either due to FeO dust grains or connected to the processing of PAHs in the supernova blast wave shock.

228

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

229

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

230

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

231

Cygnus Loop supernova remnant: new observations and a framework for understanding its structure and evolution  

International Nuclear Information System (INIS)

New observational data on the Cygnus Loop supernova remnant (SNR) include: (1) a detailed high resolution comparison of x-ray and optical emission for a field in the SE; (2) a map of the [O III] electron temperature for the field previously studied by Hester, Parker, and Dufour (1983); and (3) CCD imagery of the NE limb in the light of four emission lines. A wide range of new and existing observations of the Loop are for the first time interpreted within the context of a single physical description. The Cygnus Loop is not an evaporative SNR evolving into the McKee and Ostriker (1977) ISM, nor are tiny cloudlets necessary to explain its morphology. The data show the Cygnus Loop to be evolving into a medium consisting primarily of an intercloud phase with N0 approx. 0.1 cm-3 containing clouds with parsec dimensions and N0 less than or equal to 10 cm-3. The optical emission arises from extensive sheet like radiative shock fronts driven into the clouds. These fronts locally form the outer boundary of the remnant. The appearance of x-ray emission outside the optical emission on the limbs is due solely to projection effects. The distorted and bumpy shock front is shown to give rise in projection to the filamentary morphology of the remnant

232

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

CERN Document Server

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

233

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

234

FUSE Spectroscopy of the Large Magellanic Cloud Supernova Remnant N49  

Science.gov (United States)

Strong C III ?977 and O VI ??1032, 1038 emission lines are detected in Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of N49, the brightest optical supernova remnant in the Large Magellanic Cloud. Shocks with velocities ranging from less than 130 to more than 180 km s-1 are responsible for these emission lines and are present over the entire eastern half of the remnant. The emission lines are very broad, spanning about 700 km s-1 in all the spectra. The ratio of C III to O VI at different velocities shows that fast-moving radiative shocks are present in N49. These may be a result of instabilities, secondary shocks, and turbulent mixing. The velocity structure of O VI emission from a 4''×20'' region along the southeast edge of the remnant is the same as that from a larger 30''×30'' region, which is evidence for equally complex structure at multiple scales. An archival HST WFPC2 H? image also shows highly filamentary morphology, with structures on subarcsecond scales. The complexity of the emission suggests that the effective interstellar extinction at far-ultraviolet wavelengths is smaller than that at optical wavelengths. The uncertainty in the far-ultraviolet extinction translates to an order of magnitude uncertainty in the intrinsic O VI intensity of N49. A comparison of the O VI 1032 and 1038 Å line profiles shows that the latter is affected by absorption due to molecular hydrogen, probably associated with the remnant and its surroundings, as well as due to O I in an intermediate-velocity cloud in the Galactic halo. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer (FUSE), which is operated for NASA by Johns Hopkins University under NASA contract NAS5-32985.

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

2004-10-01

235

Supernova Shock Breakout from a Red Supergiant  

CERN Document Server

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

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

2008-01-01

236

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

237

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

CERN Document Server

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

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

2009-01-01

238

The structure of TeV-bright shell-type supernova remnants  

CERN Document Server

Aims. Two-dimensional MHD simulations are used to model the emission properties of TeV-bright shell-type supernova remnants (SNRs) and to explore their nature. Methods. In the leptonic scenario for the TeV emission, the $\\gamma$-ray emission is produced via Inverse Compton scattering of background soft photons by high-energy electrons accelerated by the shocks of the SNRs. The TeV emissivity is proportional to the magnetic field energy density and MHD simulations can be used to model the TeV structure of such remnants directly. 2D MHD simulations for SNRs are then performed under the assumption that the ambient interstellar medium is turbulent with the magnetic field and density fluctuations following a Kolmogorov-like power-law spectrum. Results. (1) As expected, these simulations confirm early 1D and 2D modelings of these sources, namely the hydrodynamical evolution of the shock waves and amplification of magnetic field by Rayleigh-Taylor convective flows and by shocks propagating in a turbulent medium; (2)...

Yang, Chuyuan; Fang, Jun; Li, Hui

2014-01-01

239

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

CERN Document Server

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

240

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

CERN Document Server

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

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

2010-01-01

 
 
 
 
241

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-06-20

242

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

243

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.)

244

What Are the Compact Central Objects in Supernova Remnants?  

Science.gov (United States)

Recent Chandra observations of the compact central objects in supernova remnants have shown puzzling results that do not seem to be consistent with either black holes or neutron stars. (See e.g. Pavlov, Sanwal, Garmire and Zavlin, astro-ph-0112322.) In particular, the inferred effective emitting surface is too small to be the entire surface of a neutron star, but too bright to be a black hole. We discuss the possibility that these compact objects might be red holes instead of black holes or neutron stars. Red holes, which occur in alternate theories of gravity, naturally predict both the greater brightness of the emissions and the smaller effective size of the emitting surface from a collapsed object of the appropriate mass.

Graber, James

2002-04-01

245

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

246

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

247

A multi-wavelength look at the young plerionic supernova remnant 0540-69.3  

CERN Document Server

We present a study of the plerionic supernova remnant 0540-69.3 in the LMC in X-ray, radio, optical, and infrared. We find that the shell of 0540-69.3 is characterized in the X-ray by thermal nonequilibrium plasma with depleted Mg and Si abundances and a temperature of kT ~ 0.7 keV. This thermal emission is superimposed with synchrotron emission in several regions. Based on X-ray spectra and on morphological considerations in all surveyed wavebands, we conclude that the shell is expanding into a clumpy and highly inhomogeneous medium. In one region of the shell we find an overabundance of Ne, suggesting the presence of ejecta near the edge of the remnant. We also see evidence for reheating of material via a reverse shock originating from the interaction of the supernova blast wave with a particularly dense cloud in the surrounding medium. Finally, we perform the first detailed study of the "halo" region extending 1.2-2.2 pc from the central pulsar. We detect the presence of thermal and nonthermal spectral com...

Brantseg, Thomas; Bozzetto, Luke M; Filipovic, Miroslav; Grieves, Nolan

2014-01-01

248

EVOLUTION OF THE RADIO REMNANT OF SUPERNOVA 1987A: MORPHOLOGICAL CHANGES FROM DAY 7000  

International Nuclear Information System (INIS)

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–1 between day 4000 and 7000 to 2400+100-200 km s–1 after day 7000. However, we emphasize that there is no conclusive evidence for a physical slowing of the shock at any given latitude in the expanding remnant, and that a change of radio morphology alone appears to dominate the evolution. This is supported by our ring-only fits which show a constant expansion of 3890 ± 50 km s–1 without deceleration between days 4000 and 9000. We suggest that once the emission latitude no longer decreases, the expansion velocity obtained from the torus model should return to the same value as that measured with the ring model

249

EVOLUTION OF THE RADIO REMNANT OF SUPERNOVA 1987A: MORPHOLOGICAL CHANGES FROM DAY 7000  

Energy Technology Data Exchange (ETDEWEB)

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{sup +150}{sub -}200 km s{sup –1} between day 4000 and 7000 to 2400{sup +100}{sub -200} km s{sup –1} after day 7000. However, we emphasize that there is no conclusive evidence for a physical slowing of the shock at any given latitude in the expanding remnant, and that a change of radio morphology alone appears to dominate the evolution. This is supported by our ring-only fits which show a constant expansion of 3890 ± 50 km s{sup –1} without deceleration between days 4000 and 9000. We suggest that once the emission latitude no longer decreases, the expansion velocity obtained from the torus model should return to the same value as that measured with the ring model.

Ng, C.-Y. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Zanardo, G.; Potter, T. M.; Staveley-Smith, L. [International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia, Crawley, WA 6009 (Australia); Gaensler, B. M. [Australian Research Council, Centre of Excellence for All-sky Astrophysics (CAASTRO) (Australia); Manchester, R. N.; Tzioumis, A. K., E-mail: ncy@bohr.physics.hku.hk [CSIRO Astronomy and Space Science, Australia Telescope National Facility, Marsfield, NSW 1710 (Australia)

2013-11-10

250

The Mipsgal View of Supernova Remnants in the Galactic Plane  

CERN Document Server

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

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

2011-01-01

251

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

CERN Document Server

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; Mori, Koji; Uchida, Hiroyuki; Petre, Robert; Yamada, Shin'ya; Tamagawa, Toru

2012-01-01

252

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

253

Supernova remnant candidates in the ROSAT All-Sky Survey  

Science.gov (United States)

Radio supernova remnants (SNRs) in the Galaxy comprise an incomplete sample of the SNR population due to various selection effects. ROSAT performed the first All-Sky Survey (RASS) with an imaging X-ray telescope and thus provided another window for finding SNRs. Schaudel (2003) searched the RASS for unknown SNRs and pinpointed about 210 candidates. Meanwhile, 14 new SNRs of his list were identified (cf. Prinz & Becker 2013 for a summary). Revisiting the RASS SNR candidates and applying more stringent selection criteria as well as taking archival XMM-Newton, Chandra and Fermi data into account the current list of RASS SNR candidates still comprises 73 sources. These sources are promising SNR candidates and studying them with e.g. eRosita will help to reveal their true nature. eRosita is an X-ray telescope which is supposed to be launched in 2016. It will perform an X-ray all-sky survey with a sensitivity of more than 10 times of what was available with ROSAT. It supports to continue the previous SNR identification campaign and may reveal other candidates not seen with ROSAT. We report on the current status of our supernova identification campaign, characterize the most promising candidates and give prospects for eRosita.

Prinz, T.; Becker, W.

2014-07-01

254

Supernova remnants with magnetars: clues to magnetar formation  

CERN Document Server

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

Vink, Jacco

2007-01-01

255

G29.7-0.3: another supernova remnant with an identity crisis  

Science.gov (United States)

New radio and X-ray observations of the galactic supernova remnant G29.7-0.3 show that it is composed of two spectrally distinct components: a steep-spectrum, incomplete shell 3 arcmin in extent enclosing a flat-spectrum, X-ray emitting region 30 arcsec across. Thus, G29.7-0.3 joins the ranks of supernova remnants which exhibit a combination of Crab-like and shell remnant attributes. The Crab-like core has the highest ratio of X-ray radio luminosity of all the Crab-like remnants observed to date, suggesting that it is an extremely young object.

Becker, R. H.; Helfand, D. J.; Szymkowiak, A. E.

1983-01-01

256

NONTHERMAL RADIATION FROM SUPERNOVA REMNANTS: EFFECTS OF MAGNETIC FIELD AMPLIFICATION AND PARTICLE ESCAPE  

International Nuclear Information System (INIS)

We explore nonlinear effects of wave-particle interactions on the diffusive shock acceleration (DSA) process in Type Ia-like supernova remnant (SNR) blast waves by implementing phenomenological models for magnetic field amplification (MFA), Alfvénic drift, and particle escape in time-dependent numerical simulations of nonlinear DSA. For typical SNR parameters, the cosmic-ray (CR) protons can be accelerated to PeV energies only if the region of amplified field ahead of the shock is extensive enough to contain the diffusion lengths of the particles of interest. Even with the help of Alfvénic drift, it remains somewhat challenging to construct a nonlinear DSA model for SNRs in which of the order of 10% of the supernova explosion energy is converted into CR energy and the magnetic field is amplified by a factor of 10 or so in the shock precursor, while, at the same time, the energy spectrum of PeV protons is steeper than E –2. To explore the influence of these physical effects on observed SNR emission, we also compute the resulting radio-to-gamma-ray spectra. Nonthermal emission spectra, especially in X-ray and gamma-ray bands, depend on the time-dependent evolution of the CR injection process, MFA, and particle escape, as well as the shock dynamic evolution. This result comes from the fact that the high-energy end of the CR spectrum is composed of particles that are injected in the very early stages of the blast wave evolution. Thus, it is crucial to better understand the plasma wave-particle interactions associated with collisionless shocks in detailed modeling of nonthermal radiation from SNRs

257

NONTHERMAL RADIATION FROM SUPERNOVA REMNANTS: EFFECTS OF MAGNETIC FIELD AMPLIFICATION AND PARTICLE ESCAPE  

Energy Technology Data Exchange (ETDEWEB)

We explore nonlinear effects of wave-particle interactions on the diffusive shock acceleration (DSA) process in Type Ia-like supernova remnant (SNR) blast waves by implementing phenomenological models for magnetic field amplification (MFA), Alfvénic drift, and particle escape in time-dependent numerical simulations of nonlinear DSA. For typical SNR parameters, the cosmic-ray (CR) protons can be accelerated to PeV energies only if the region of amplified field ahead of the shock is extensive enough to contain the diffusion lengths of the particles of interest. Even with the help of Alfvénic drift, it remains somewhat challenging to construct a nonlinear DSA model for SNRs in which of the order of 10% of the supernova explosion energy is converted into CR energy and the magnetic field is amplified by a factor of 10 or so in the shock precursor, while, at the same time, the energy spectrum of PeV protons is steeper than E {sup –2}. To explore the influence of these physical effects on observed SNR emission, we also compute the resulting radio-to-gamma-ray spectra. Nonthermal emission spectra, especially in X-ray and gamma-ray bands, depend on the time-dependent evolution of the CR injection process, MFA, and particle escape, as well as the shock dynamic evolution. This result comes from the fact that the high-energy end of the CR spectrum is composed of particles that are injected in the very early stages of the blast wave evolution. Thus, it is crucial to better understand the plasma wave-particle interactions associated with collisionless shocks in detailed modeling of nonthermal radiation from SNRs.

Kang, Hyesung [Department of Earth Sciences, Pusan National University, Pusan 609-735 (Korea, Republic of); Jones, T. W. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Edmon, Paul P., E-mail: kang@uju.es.pusan.ac.kr, E-mail: twj@msi.umn.edu, E-mail: pedmon@cfa.harvard.edu [Research Computing, Harvard University, Cambridge, MA 02138 (United States)

2013-11-01

258

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

259

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

CERN Document Server

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

Drury, Luke O'C

2010-01-01

260

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

CERN Document Server

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

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

2012-01-01

 
 
 
 
261

On cosmic ray acceleration in supernova remnants and the FERMI/PAMELA data  

CERN Document Server

We discuss recent observations of high energy cosmic ray positrons and electrons in the context of hadronic interactions in supernova remnants, the suspected accelerators of galactic cosmic rays. Diffusive shock acceleration can harden the energy spectrum of secondary positrons relative to that of the primary protons (and electrons) and thus explain the rise in the positron fraction observed by PAMELA above 10 GeV. We normalize the hadronic interaction rate by holding pion decay to be responsible for the gamma-rays detected by HESS from some SNRs. By simulating the spatial and temporal distribution of SNRs in the Galaxy according to their known statistics, we are able to then fit the electron (plus positron) energy spectrum measured by Fermi. It appears that IceCube has good prospects for detecting the hadronic neutrino fluxes expected from nearby SNRs.

Ahlers, Markus; Sarkar, Subir

2009-01-01

262

Swift Observations of Supernovae during and after Shock Breakout  

Science.gov (United States)

Over the past few years, space-based observatories have allowed detailed studies of energetic supernova explosions in previously unexplored time domains and wavelength regimes. NASA's Swift observatory is playing an important role in probing the early emission of SNe during and after shock breakout due to its fast response, flexible scheduling capabilities, and large wavelength band coverage, ranging from the optical, W, and X-ray to the Gamma-ray bands. By studying the outgoing SN shocks with material in its surroundings, the explosion physics and nature of progenitor stars can be studied. Furthermore, monitoring the X-ray emission of SNe with space-based X-ray observatories is being used to map the density structure in SN environments out to large radii from the sites of the explosions (>E20 cm), the transition of a SN into an old supernova remnant can be studied, and the mass-loss rates of the progenitor stars are being probed over significant timescales (>E4 years) in the stellar wind history. In combination, these observations give unprecedented insights into the nature of energetic explosions and their environments. During this talk, I will present highlights from recent observations, among them the first observation of a SN DURING the actual explosion with Swift, and I will discuss the "naked eye" burst at a redshift of -1, which was the most distant object humans could ever see with their own eyes.

Immler, Stefan

2008-01-01

263

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

264

Comparing supernova remnants around strongly magnetized and canonical pulsars  

Science.gov (United States)

The origin of the strong magnetic fields measured in magnetars is one of the main uncertainties in the neutron star field. On the other hand, the recent discovery of a large number of such strongly magnetized neutron stars is calling for more investigation on their formation. The first proposed model for the formation of such strong magnetic fields in magnetars was through alpha-dynamo effects on the rapidly rotating core of a massive star. Other scenarios involve highly magnetic massive progenitors that conserve their strong magnetic moment into the core after the explosion, or a common envelope phase of a massive binary system. In this work, we do a complete re-analysis of the archival X-ray emission of the supernova remnants (SNRs) surrounding magnetars, and compare our results with all other bright X-ray emitting SNRs, which are associated with compact central objects (which are proposed to have magnetar-like B-fields buried in the crust by strong accretion soon after their formation), high-B pulsars and normal pulsars. We find that emission lines in SNRs hosting highly magnetic neutron stars do not differ significantly in elements or ionization state from those observed in other SNRs, neither averaging on the whole remnants, nor studying different parts of their total spatial extent. Furthermore, we find no significant evidence that the total X-ray luminosities of SNRs hosting magnetars, are on average larger than that of typical young X-ray SNRs. Although biased by a small number of objects, we found that for a similar age, there is the same percentage of magnetars showing a detectable SNR than for the normal pulsar population.

Martin, J.; Rea, N.; Torres, D. F.; Papitto, A.

2014-11-01

265

The Hubble Heritage Image of the Crab Nebula Supernova Remnant  

Science.gov (United States)

The Hubble Heritage Project has the aim of providing the public with pictorially striking images of celestial objects obtained with NASA's Hubble Space Telescope. Here we present a 5-color Wide Field Planetary Camera 2 (WFPC2) image of the Crab Nebula, a ~950 year old supernova remnant located 6500 light-years distant in the constellation Taurus. The images were obtained in 1995 January and April, and the science investigation reporting results was published by Blair, W. P., et al. (1997, ApJS, 109, 473--480). Over 10 hours of exposure time through 5 separate optical continuum band and emission-line filters were used to study size scales and ionization structures of the filaments and newly synthesized dust within the expanding ejecta. The Heritage version of these data shows several important aspects of the Crab Nebula all in one spectacular image. The continuum image shows stars, including the enigmatic pulsar (the collapsed core of the original star) and the ghostly diffuse synchrotron nebula energized by the pulsar. The synchrotron nebula in turn heats and ionizes the surrounding clumpy filaments of gas and dust visible in the emission line images. These filaments are the supernova ejecta that were expelled during the explosion and are now expanding outward from the pulsar at high speed. The different colors in the picture show optical emission lines of hydrogen (orange), nitrogen (red), sulfur (pink) and oxygen (bluish-green). The subtle changes in color from one filament to the next arise because of varying temperatures and densities of the gas, and variable chemical abundances of the ``star stuff," or the doppler shifting of emission into or out of the various narrow filter bandpasses. Support for this work was provided by NASA through grant numbers GO-07632.01-96A and GO-5354.04-93A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Blair, W. P.; English, J.; Bond, H. E.; Christian, C. A.; Frattare, L.; Hamilton, F.; Levay, Z.; Noll, K. S.

2000-05-01

266

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

Science.gov (United States)

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 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 on the order of the point-spread function of Chandra, while they are 0.5"-40" (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 SRCUT) models. The former requires unrealistic high temperature (>~2 keV) and low abundances (<~1 solar) for emission from young SNRs and may be thus unlikely. The latter reproduces the spectra with best-fit photon indices of 2.1-3.8, or roll-off frequencies of (0.1-28)×1017 Hz, which reminds us of the synchrotron emission from electrons accelerated via DSA. We consider various physical parameters as functions of the SNR age, including the previous results on SN 1006; the filament width on the downstream side increases with the SNR age, and the spectrum becomes softer, keeping a nonthermal feature. It was also found that a function, that is, the roll-off frequency divided by the square of the scale width on the downstream side, shows negative correlation with the age, which might provide us some information on the DSA theory.

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

2005-03-01

267

CHANDRA AND XMM OBSERVATIONS OF THE COMPOSITE SUPERNOVA REMNANT G327.1-1.1  

International Nuclear Information System (INIS)

We present new X-ray imaging and spectroscopy of a composite supernova remnant G327.1-1.1 using the Chandra and XMM-Newton X-ray observatories. G327.1-1.1 has an unusual morphology consisting of a symmetric radio shell and an off center nonthermal component that indicates the presence of a pulsar wind nebula (PWN). Radio observations show a narrow finger of emission extending from the PWN structure toward the northwest. X-ray studies with ASCA, ROSAT, and BeppoSAX revealed elongated extended emission and a compact source at the tip of the finger that may be coincident with the actual pulsar. The high resolution Chandra observations provide new insight into the structure of the inner region of the remnant. The images show a compact source embedded in a cometary structure from which a trail of X-ray emission extends in the southeast direction. The Chandra images also reveal two prong-like structures that appear to originate from the vicinity of the compact source and extend into a large bubble that is oriented in the northwest direction, opposite from the bright radio PWN. The emission from the entire radio shell is detected in the XMM data and can be characterized by a thermal plasma model with a temperature of ? 0.3 keV, which we use to estimate the physical properties of the remnant. The peculiar morphology of G327.1-1.1 may be explained by the emission from a moving pulsar and a relic PWN that has been disrupted by the reverse shock.se shock.

268

INFRARED SPECTRAL MAPPING OF SUPERNOVA REMNANTS. I. N63A AND ITS ENVIRONMENT  

Energy Technology Data Exchange (ETDEWEB)

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, H{sub 2} lines, and polycyclic aromatic hydrocarbons (PAHs). The lines contribute half of the flux in the Spitzer 24 {mu}m image of N63A shocked lobes, but only {<=}10% elsewhere. The mid-IR flux is largely due to thermal continuum emission from dust in and around N63A plasma. 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 {approx}0.07 M{sub Sun} of hot grains, comparable to amounts in other SNRs. Within N63A there is {approx}0.7 M{sub Sun} 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.

Caulet, Adeline [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801-3080 (United States); Williams, Rosa M., E-mail: adel-col@orange.fr [Department of Earth and Space Sciences, Columbus State University, 701 Front Ave., Columbus, GA 31901 (United States)

2012-12-20

269

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

270

Updated radio $\\Sigma-D$ relation for Galactic supernova remnants  

CERN Document Server

We present updated empirical radio surface-brightness-to-diameter ($\\Sigma-D$) relation for supernova remnants (SNRs) in our Galaxy. Our original calibration sample of Galactic SNRs with independently determined distances (Pavlovi\\'c et al. 2013, hereafter Paper I) is reconsidered and updated with data which became available in the past two years. The orthogonal fitting procedure and probability-density-function-based (PDF) method are applied to the calibration sample in the $\\log \\Sigma - \\log D$ plane. Orthogonal regression keeps $\\Sigma-D$ and $D-\\Sigma$ relations invariant. Our previous Monte Carlo simulations verified that the slopes of the empirical $\\Sigma-D$ relation should be determined by using orthogonal regression. Updated calibration sample contains 65 shell SNRs. 6 new Galactic SNRs are added to the sample from Paper I, one is omitted and distances are changed for 10 SNRs. The slope derived here is slightly steeper ($\\beta \\approx 5.2$) than $\\Sigma-D$ slope in Paper I ($\\beta \\approx 4.8$). The...

Pavlovi?, M Z; Vukoti?, B; Uroševi?, D

2014-01-01

271

Fermi LAT observation of supernova remnant HB9  

Science.gov (United States)

A 5.5-yr 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 16?. The gamma-ray flux above 0.2 GeV is (2.23 ± 0.19stat) × 10-8 photons cm-2 s-1, and the corresponding luminosity above 1 GeV is 1.4 × 1033 erg s-1 (for a source distance of 1 kpc). The spectrum of the source is best described by curved power law (log-parabola, dN/dE=N_0 E^{-(? +? log(E/1 GeV))} with ? = (2.24 ± 0.09stat) and ? = 0.4 ± 0.1stat)). The gamma-ray spectrum of the source 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

2014-10-01

272

Non-thermal emission from old supernova remnants  

CERN Document Server

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

Fang, Jun

2007-01-01

273

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

274

XMM-Newton Observations of Two Candidate Supernova Remnants  

CERN Document Server

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

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

2011-01-01

275

Magnetic field decay of magnetars in supernova remnants  

CERN Document Server

In this paper, we modify our previous research carefully, and derive a new expression of electron energy density in superhigh magnetic fields. Based on our improved model, we re-compute the electron capture rates and the magnetic fields' evolutionary timescales $t$ of magnetars. According to the calculated results, the superhigh magnetic fields may evolve on timescales $\\sim (10^{6}-10^{7})$ yrs for common magnetars, and the maximum timescale of the field decay, $t\\approx 2.9507 \\times 10^{6}$ yrs, corresponding to an initial internal magnetic field $B_{\\rm 0}= 3.0 \\times 10^ {15}$ G and an initial inner temperature $T_{\\rm 0}= 2.6 \\times 10^ {8}$ K. Motivated by the results of the neutron star-supernova remnant(SNR) association of Zhang $\\&$ Xie(2011), we calculate the maximum $B_{\\rm 0}$ of magnetar progenitors, $B_{\\rm max}\\sim (2.0\\times 10^{14}-2.93 \\times 10^{15})$ G when $T_{\\rm 0}= 2.6 \\times 10^ {8}$ K. When $T_{\\rm 0}\\sim 2.75 \\times 10^ {8}-~1.75 \\times 10^ {8}$ K, the maximum $B_{\\rm 0}$ will ...

Gao, Z F; Wang, N; Yuan, J P

2013-01-01

276

Fermi LAT Observation of Supernova Remnant HB9  

CERN Document Server

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

277

Interstellar and Ejecta Dust in the Cas A Supernova Remnant  

CERN Document Server

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. Using low resolution Spitzer IRS spectra (5-35 $\\mu$m), and broad-band Herschel PACS imaging (70, 100, and 160 $\\mu$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 $\\sim9$ and 21 $\\mu$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 Al$_2$O$_3$ 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 e...

Arendt, Richard G; Kober, Gladys; Rho, Jeonghee; Hwang, Una

2014-01-01

278

X-ray ejecta kinematics of the Galactic core-collapse supernova remnant G292.0+1.8  

CERN Document Server

We report on the results from the analysis of our 114 ks Chandra HETGS observation of the Galactic core-collapse supernova remnant G292.0+1.8. To probe the 3D structure of the clumpy X-ray emitting ejecta material in this remnant, we measured Doppler shifts in emission lines from metal-rich ejecta knots projected at different radial distances from the expansion center. We estimate radial velocities of ejecta knots in the range of -2300 <~ v_r <~ 1400 km s^-1. The distribution of ejecta knots in velocity vs. projected-radius space suggests an expanding ejecta shell with a projected angular thickness of ~90" (corresponding to ~3 pc at d = 6 kpc). Based on this geometrical distribution of the ejecta knots, we estimate the location of the reverse shock approximately at the distance of ~4 pc from the center of the supernova remnant, putting it in close proximity to the outer boundary of the radio pulsar wind nebula. Based on our observed remnant dynamics and the standard explosion energy of 10^51 erg, we est...

Bhalerao, Jayant; Dewey, Daniel; Hughes, John P; Mori, Koji; Lee, Jae-Joon

2014-01-01

279

An X-ray study of the supernova remnant G20.0-0.2 and its surroundings  

CERN Document Server

Aims: We study the supernova remnant G20.0-0.2 and its surroundings in order to look for the high energy counterpart of the radio nebula and to find evidence of interaction between the shock front and the interstellar medium. Methods: We used Chandra archival observations to analyze the X-ray emission from the supernova remnant. The surrounding gas was investigated using data extracted from the Galactic Ring Survey, the VLA Galactic Plane Survey, the Galactic Legacy Infrared Midplane Survey Extraordinaire, and the Bolocam Galactic Plane Survey. Results: G20.0-0.2 shows diffuse X-ray emission from the central region of the radio remnant. Although the current data do not allow us to distinguish between a thermal or non-thermal origin for the X-ray diffuse emission, based on the radio properties we suggest a synchrotron origin as the most favorable. The hard X-ray point source CXO J182807.4-113516 appears located at the geometrical center of the remnant and is a potential candidate to be the pulsar powering the ...

Petriella, Alberto; Giacani, Elsa

2013-01-01

280

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

 
 
 
 
281

Nonthermal radiation of young supernova remnants: the case of Cas A  

CERN Document Server

The processes responsible for the broad-band radiation of the young supernova remnant Cas A are explored using a new code which is designed for a detailed treatment of the diffusive shock acceleration of particles in 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 LAT 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...

Zirakashvili, V N; Yang, R; Ona-Wilhelmi, E; Tuffs, R J

2013-01-01

282

THE ORIGIN OF RADIALLY ALIGNED MAGNETIC FIELDS IN YOUNG SUPERNOVA REMNANTS  

Energy Technology Data Exchange (ETDEWEB)

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

Inoue, Tsuyoshi; Shimoda, Jiro; Ohira, Yutaka; Yamazaki, Ryo, E-mail: inouety@phys.aoyama.ac.jp [Department of Physics and Mathematics, Aoyama-Gakuin University, Sagamihara, Kanagawa 252-5258 (Japan)

2013-08-01

283

Spectra of Cosmic Ray Protons and Helium Produced in Supernova Remnants  

CERN Document Server

Data obtained in the ATIC-2 (Advanced Thin Ionization Calorimeter), CREAM (Cosmic Ray Energetics and Mass)) and PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) experiments suggest that elemental interstellar spectra of cosmic rays below the knee at a few times $10^{6}$ GeV are not simple power laws, but they experience hardening at magnetic rigidity above about 240 GV. Another essential feature is the difference between proton and Helium energy spectra, so that the He/p ratio increases by more than 50% in the energy range from $10^{2}$ to $10^{4}$ GV. We consider the concavity of particle spectrum resulting from the nonlinear nature of diffusive shock acceleration in supernova remnants (SNR) as a possible reason for the observed spectrum hardening. Helium-to-proton ratio increasing with energy can be interpreted as a consequence of cosmic ray acceleration by forward and reverse shocks in SNRs. The contribution of particles accelerated by reverse shocks makes the concavity of t...

Ptuskin, V S; Seo, E S

2012-01-01

284

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

285

The Expansion Rate, Age, and Distance of the Supernova Remnant G266.2-1.2  

Science.gov (United States)

We reprocessed and analyzed the 2003 and 2008 Chandra ACIS data for the supernova remnant G266.2-1.2. The data for two adjacent annular wedges along a relatively bright and narrow portion of the northwestern rim indicate that it has moved by about 2.39 ± 0.57 arcsec over a period of 5.652 yr. The corresponding expansion rate (0.42 ± 0.10 arcsec/yr or 13.6 ± 5.7 %/kyr) is about half of the rate reported for an analysis of XMM data from a similar region of the remnant over a similar time interval (Katsuda, Tsunemi & Mori, 2008). A hydrodynamic analysis was performed using the models of Truelove & McKee (1999). Many scenarios were considered using broad ranges of initial kinetic energies, ejecta masses, ejecta mass density distributions, ambient densities, and evolutionary states. The results were constrained by the Chandra expansion rate (assuming it is representative of the remnant as a whole), an inferred lower limit on the forward shock speed, an upper limit on the inferred thermal X-ray emission, and energy considerations. The results of this analysis suggest that G266.2-1.2 is most likely between 2.4 and 5.1 kyr old, whether or not it was produced by a type Ia or type II event. If the remnant is expanding into the material shed by a steady stellar wind instead of a uniform ambient medium, then it could be older by a factor of up to 1.5. In no case is the remnant expected to be younger than 2.2 kyr. Therefore, it is too old to be associated with emission from the decay of Ti-44 or with features in the abundance of nitrate in South Pole ice core samples. The hydrodynamic results provide only a weak constraint on the distance of G266.2-1.2. An analysis of previously-published distance estimates and constraints suggests that the remnant is between about 0.5 and 1.0 kpc. This limitation does not significantly affect the estimate of the age. We adopt the distance of thecloser of two groups of material in the Vela Molecular Ridge (i.e. 0.7 ± 0.2 kpc, Liseau et al. 1992). This distance is consistent with the progenitor having been a member of the Vel OB1 association (Eggen 1982).

Allen, Glenn E.; DeLaney, Tracey; Filipovic, Miroslav D; Houck, John C.; Pannuti, Thomas; Stage, Michael D.

2014-08-01

286

SUPERNOVA REMNANT KES 17: AN EFFICIENT COSMIC RAY ACCELERATOR INSIDE A MOLECULAR CLOUD  

International Nuclear Information System (INIS)

The 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 ?-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 concluding that the strong magnetic field, turbulence, and clumpy nature of molecular clouds enhance 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

287

SUPERNOVA REMNANT KES 17: AN EFFICIENT COSMIC RAY ACCELERATOR INSIDE A MOLECULAR CLOUD  

Energy Technology Data Exchange (ETDEWEB)

The 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 ?-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 concluding that the strong magnetic field, turbulence, and clumpy nature of molecular clouds enhance 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. [NYU Abu Dhabi, P.O. Box 903, New York, NY 10276 (United States); Castro, Daniel [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue 37-241, Cambridge, MA 02139 (United States); Slane, Patrick O. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Temim, Tea [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Hughes, John P. [Department of Physics and Astronomy Rutgers University 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Rakowski, Cara, E-mail: jg168@cosmo.nyu.edu, E-mail: cara.rakowski@gmail.com [United States Patent and Trademark Office, 600 Dulany Street, Alexandria, VA (United States)

2013-11-10

288

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

CERN Document Server

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

289

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

CERN Document Server

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

Kishishita, Tetsuichi; Uchiyama, Yasunobu

2013-01-01

290

Molecular Environment and an X-ray Spectroscopy of Supernova Remnant Kesteven 78  

CERN Document Server

We have investigated the molecular environment of the Galactic supernova remnant (SNR) Kesteven 78 and performed an XMM-Newton X-ray spectroscopic study for the northeastern edge of the remnant. SNR Kes78 is found to interact with the molecular clouds (MCs) at a systemic local standard of rest velocity of 81km/s. At around this velocity, the SNR appears to contact a long molecular strip in the northeast and a large cloud in the east as revealed in 13CO line, which may be responsible for the radio brightness peak and the OH maser, respectively. The 12CO-line bright region and the region with enhanced 12CO J=1-0/13CO J=1-0 ratios both morphologically match the eastern bright radio shell in general, and the SNR is consistent in extent with a CO cavity. Broadened 12CO lines and relative enhancement of 12CO J=2-1 to 12CO J=1-0 in the maser region and the western clumpy molecular arc may be kinematic signature of shock perturbation. The SNR-MC association places the SNR at a kinematic distance of 4.8 kpc. The X-ray...

Zhou, Ping

2011-01-01

291

The X-ray structure and mass of the Cassiopeia A supernova remnant  

International Nuclear Information System (INIS)

The X-ray images of the Cassiopeia supernova remnant from the Einstein Observatory have been processed by a maximum-entropy algorithm. The emission appears to originate in two concentric thin shells. The image of highest resolution (about 4 arcsec) has been used to derive temperature and density maps of the remnant assuming that the X-ray emission is thermal and from an optically thin hot gas. These maps are consistent with both pressure equilibrium and the overall X-ray spectrum. The mass of X-ray emitting gas is found to be at least 15 solar masses, which is considerably more than observed directly at other wavelengths. The X-ray structure and dynamics of Cas A are consistent with it being in a 'free-expansion' phase of evolution, with the bulk of the emission from a reverse shock in the ejecta. The progenitor star is likely to have been massive, as seems to be required by the element abundances of the optical knots. (author)

292

On the Hadronic Gamma-ray Emission from Tycho's Supernova Remnant  

CERN Document Server

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

Zhang, Xiao; Li, Hui; Zhou, Xin

2012-01-01

293

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

CERN Document Server

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

294

The Use of Multiwavelength Archival Observational Data for Scientific Discoveries: A Case of the Supernova Remnant Cassiopeia A  

Science.gov (United States)

Most of the high-quality astronomical data after a proprietary period of typically one year are provided to open access, allowing researchers to complement their observations with the archival data in other wavelength bands, thus improving quality of the data analysis. This paper presents one example of such a use -- studies of the reverse shock front passing through an oxygen-rich material in the young supernova remnant Cassiopeia A. The paper is based on the contribution to the ``Baltic Applied Astroinformatics and Space Data Processing'' conference, held on 2012 May 7--8 in Ventspils, Latvia.

Docenko, Dmitrijs

295

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The escape of charged particles accelerated by diffusive shock acceleration from supernova remnants is shown to be a more complex process than normally appreciated. Using a box model it is shown that the high-energy end of the spectrum can exhibit spectral breaks even with no formal escape as a result of geometrical dilution and changing time-scales. It is pointed out that the bulk of the cosmic ray particles at lower energies must be produced and released in the late stages...

Drury, Luke O. C.

2010-01-01

296

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

297

Carbon Monoxide Observations Toward the Supernova Remnant 3C 391: Interaction Confirmed  

Science.gov (United States)

We present observations of the J = 1 -> 0 transition of CO toward the radio-bright supernova remnant 3C 391 made with the NRAO 12-m telescope.(*) Our earlier radio continuum observations of 3C 391 showed a morphology strongly suggestive of evolution near a density discontinuity in the external medium. In this interpretation, the supernova went off near the edge of a moderately dense molecular cloud, and after a few hundred to a thousand years the blast wave broke out of the edge of the cloud to emerge as a larger, lower surface-brightness extension to the SNR. Survey data indicated nearby CO at appropriate velocities but direct evidence for interaction was lacking. Our new observations strongly support the interaction picture. CO contours drop steeply at the location of the inner edge of the SNR radio emission; the ``blowout'' extension is in the direction of steepest decrease of CO contours. Extensions on the bright limb of radio continuum perfectly match the edges of a strong CO condensation. A consistent picture then involves the SNR blast wave eating its way into the molecular cloud, destroying CO as it goes. The data also indicate directly that shock acceleration of electrons at least to 10 GeV or so is possible even for a blast wave encountering dense neutral material. We describe the quantitative implications of the interaction picture for 3C 391 and for SNRs in general. (*) The NRAO is operated by Associated Universities, Inc., under a cooperative agreement with the National Science Foundation.

Wilner, D. J.; Reynolds, S. P.; Moffett, D. A.

1996-05-01

298

Filling the gap between supernova explosions and their remnants: the Cassiopeia A laboratory  

Science.gov (United States)

Supernova remnats (SNRs) show a complex morphology characterized by an inhomogeneous spatial distribution of ejecta, believed to reflect pristine structures and features of the progenitor supernova (SN) explosion. Filling the gap between SN explosions and their remnants is very important for a comprehension of the origin of present-day structure of ejecta in SNRs and to probe and constraint current models of SN explosions. The SNR Cassiopeia A (Cas A) is an attractive laboratory for studying the SNe-SNRs connection, being one of the best studied SNRs for which its 3D structure is known. We present a three-dimensional hydrodynamic model describing the evolution of Cas A from the immediate aftermath of the SN explosion to its expansion through the interstellar medium, taking into account the distribution of element abundances of the ejecta, the backreaction of accelerated cosmic rays at the shock front, and the deviations from equilibrium of ionizazion for the most important elements. We use the model to derive the physical parameters characterizing the SN explosion and reproducing the today morphology of Cas A.

Orlando, S.; Miceli, M.; Pumo, M.; Bocchino, F.; Reale, F.; Peres, G.

2014-07-01

299

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

300

Discovery of the supernova remnant G351.0-5.4  

Science.gov (United States)

While searching the NRAO VLA Sky Survey (NVSS) for diffuse radio emission, we have serendipitously discovered extended radio emission close to the Galactic plane. The radio morphology suggests the presence of a previously unknown Galactic supernova remnant. An unclassified ?-ray source detected by EGRET (3EG J1744-3934) is present in the same location and may stem from the interaction between high-speed particles escaping the remnant and the surrounding interstellar medium. Our aim is to confirm the presence of a previously unknown supernova remnant and to determine a possible association with the ?-ray emission 3EG J1744-3934. We have conducted optical and radio follow-ups of the target using the Dark Energy Camera (DECam) on the Blanco telescope at Cerro Tololo Inter-American Observatory (CTIO) and the Giant Meterwave Radio Telescope (GMRT). We then combined these data with archival radio and ?-ray observations. While we detected the extended emission in four different radio bands (325, 1400, 2417, and 4850 MHz), no optical counterpart has been identified. Given its morphology and brightness, it is likely that the radio emission is caused by an old supernova remnant no longer visible in the optical band. Although an unclassified EGRET source is co-located with the supernova remnant, Fermi-LAT data do not show a significant ?-ray excess that is correlated with the radio emission. However, in the radial distribution of the ?-ray events, a spatially extended feature is related to supernova remnant at a confidence level of ~1.5?. We classify the newly discovered extended emission in the radio band as the old remnant of a previously unknown Galactic supernova: SNR G351.0-5.4. FITS files of Figs. 1 and 5 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568/A107

de Gasperin, F.; Evoli, C.; Brüggen, M.; Hektor, A.; Cardillo, M.; Thorman, P.; Dawson, W. A.; Morrison, C. B.

2014-08-01

 
 
 
 
301

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

Science.gov (United States)

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

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

2013-03-01

302

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

CERN Document Server

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

Caprioli, Damiano

2012-01-01

303

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

304

An Extreme Pulsar Tail Protruding from the Frying Pan Supernova Remnant  

CERN Document Server

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

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

2011-01-01

305

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

International Nuclear Information System (INIS)

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

306

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

307

Observational study of ion-electron equilibration and of cloud evaporation in supernova remnants under the HEAO-2 guest investigator program  

Science.gov (United States)

Observations of three selected supernovae remnants (Cygnus Loop, IC 443, and Puppis A) were made in the forbidden coronal iron lines (Fe X) lambda 6374 and (Fe XIV) lambda 5303. The resulting data was compared quantitatively with Einstein images of the same objects, and an attempt was made to determine (a) the process by which ion and electron energies are equilibrated behind the shock front in the ISM and (b) whether cloud evaporation occurs within the hot remnant interiors. Spatially-resolved X ray emission were modeled for Sedov-Taylor blast wave models of supernovae remnants (SNR) under conditions of non-equlibrium ionization. The computations are intended to provide results that can be directly compared with Einstein high resolution image (HRI) and imaging proportional counter (IPS) data. The computer program for predicting the spatial distribution of HRI and IPS counting rates was completed, and final testing of it had begun.

Teske, R. G.

1986-01-01

308

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.

309

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

310

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

311

Nonthermal emission of supernova remnant SN 1006 revisited: theoretical model and the H.E.S.S. results  

CERN Document Server

The properties of the Galactic supernova remnant (SNR) SN 1006 are theoretically re-analyzed in the light of the recent H.E.S.S. results. Nonlinear kinetic theory is used to determine the momentum spectrum of cosmic rays (CRs) in space and time in the supernova remnant SN 1006. The physical parameters of the model - proton injection rate, electron-to-proton ratio and downstream magnetic field strength - are determined through a fit of the result to the observed spatially-integrated synchrotron emission properties. The only remaining unknown astronomical parameter, the circumstellar gas number density, is determined by a normalization of the amplitude of the gamma-ray flux to the observed amplitude. The bipolar morphology of both nonthermal X-ray and gamma-ray emissions is explained by the preferential injection of suprathermal nuclei and subsequent magnetic field amplification in the quasi-parallel regions of the outer supernova shock. The above parameters provide an improved fit to all existing nonthermal em...

Berezhko, E G; Voelk, H J

2012-01-01

312

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 6.9x104 solar mass and the expansion velocity of 20 km/s. The parameters of the supernova remnant are derived (age 5.8x105 years, initial energy 8.4x1051 ergs) and some conclusions on a possible genetic connection between H II regions and the supernova remnant are made

313

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

CERN Document Server

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

314

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.

315

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 105-1053 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 2x1052 ergs of a supermassive star with the mass of about 103 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

316

Observations of Supernova Remnants and Pulsar Wind Nebulae: A VERITAS Key Science Project  

CERN Document Server

The study of supernova remnants and pulsar wind nebulae was one of the Key Science Projects for the first two years of VERITAS observations. VERITAS is an array of four imaging Cherenkov telescopes located at the Whipple Observatory in southern Arizona. Supernova remnants are widely considered to be the strongest candidate for the source of cosmic rays below the knee at around 10^15 eV. Pulsar wind nebulae are synchrotron nebulae powered by the spin-down of energetic young pulsars, and comprise one of the most populous very-high-energy gamma-ray source classes. This poster will summarize the results of this observation program.

Humensky, Brian

2009-01-01

317

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)

318

Magnetic field amplification in Tycho and other shell-type supernova remnants  

Science.gov (United States)

It is shown that amplification of the magnetic field in supernova remnants (SNRs) occurs in all six objects where morphological measurements are presently available in the hard X-ray continuum at several keV. For the three archetypical objects (SN 1006, Cas A and Tycho's SNR) to which nonlinear time-dependent acceleration theory has been successfully applied up to now, the global theoretical and the local observational field strengths agree very well, suggesting in addition that all young SNRs exhibit the amplification effect as a result of very efficient acceleration of nuclear cosmic rays (CRs) at the outer shock. Since this appears to be empirically the case, we may reverse the argument and consider field amplification as a measure of nuclear CR acceleration and it has indeed been argued that acceleration in the amplified fields allows the CR spectrum from SNRs to reach the knee in the spectrum or, in special objects, even beyond. The above results are furthermore used to investigate the time evolution of field amplification in young SNRs. Although the uncertainties in the data do not allow precise conclusions regarding this point, they rather clearly show that the ratio of the magnetic field energy density and the kinetic energy density of gas flow into the shock is of the order of a few percent if the shock speed is high enough V_s>103 km s-1, and this ratio remains nearly constant during the SNR evolution. The escape of the highest energy nuclear particles from their sources becomes progressively important with age, reducing also the cutoff in the ?^0-decay gamma-ray emission spectrum with time after the end of the sweep-up phase. Simultaneously the leptonic gamma-ray channels will gain in relative importance with increasing age of the sources.

Völk, H. J.; Berezhko, E. G.; Ksenofontov, L. T.

2005-04-01

319

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)

320

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

 
 
 
 
321

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 ?

322

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

323

The supernova remnant RX J0852.0-4622: radio characteristics and implications for SNR statistics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present new radio observations of the recently identified, young Galactic supernova remnant (SNR) RX J0852.0-4622 (G266.2-01.2) made at 1.40 GHz with a resolution of 14.9 arcmin. These results, along with other radio observations from the literature, are used to derive the extent, morphology and radio spectrum of the remnant. The possible age and distance to this remnant are discussed, along with the consequences of its properties - especially its low radio surface bright...

Duncan, A. R.; Green, D. A.

2000-01-01

324

SHOCK BREAKOUT FROM TYPE Ia SUPERNOVA  

International Nuclear Information System (INIS)

The mode of explosive burning in Type Ia supernovae (SNe Ia) remains an outstanding problem. It is generally thought to begin as a subsonic deflagration, but this may transition into a supersonic detonation (the delayed detonation transition, DDT). We argue that this transition leads to a breakout shock, which would provide the first unambiguous evidence that DDTs occur. Its main features are a hard X-ray flash (?20 keV) lasting ?10-2 s with a total radiated energy of ?1040 erg, followed by a cooling tail. This creates a distinct feature in the visual light curve, which is separate from the nickel decay. This cooling tail has a maximum absolute visual magnitude of MV ? -9 to -10 at ?1 day, which depends most sensitively on the white dwarf radius at the time of the DDT. As the thermal diffusion wave moves in, the composition of these surface layers may be imprinted as spectral features, which would help to discern between SN Ia progenitor models. Since this feature should accompany every SNe Ia, future deep surveys (e.g., m = 24) will see it out to a distance of ?80 Mpc, giving a maximum rate of ?60 yr-1. Archival data sets can also be used to study the early rise dictated by the shock heating (at ?20 days before maximum B-band light). A similar and slightly brighter event may also accompany core bounce during the accretion-induced collapse to a neutron star, but with a lower occurrence rate.

325

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-11-15

326

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

International Nuclear Information System (INIS)

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

327

XMM-NEWTON OBSERVATIONS OF TWO CANDIDATE SUPERNOVA REMNANTS  

Energy Technology Data Exchange (ETDEWEB)

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, {approx}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, {tau} = 147 kyr, E-dot = 5.8 Multiplication-Sign 10{sup 35} erg s{sup -1}, d = 5.7 kpc), with the PWN luminosity L{sub 0.2-10keV} Almost-Equal-To 5 Multiplication-Sign 10{sup 33} erg s{sup -1} Almost-Equal-To 8 Multiplication-Sign 10{sup -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, {tau} = 161 kyr, E-dot = 9.3 Multiplication-Sign 10{sup 33} erg s{sup -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, {tau} = 23 kyr, E-dot = 5.5 Multiplication-Sign 10{sup 36} erg s{sup -1}) embedded in a PWN with extent of 1.'3. The unabsorbed pulsar + PWN luminosity is L{sub 2-11keV} Almost-Equal-To 2 Multiplication-Sign 10{sup 34} erg s{sup -1} Almost-Equal-To 4 Multiplication-Sign 10{sup -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 L{sub 2-10keV} Almost-Equal-To 4 Multiplication-Sign 10{sup 33} erg s{sup -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.

Kargaltsev, O. [Department of Astronomy, University of Florida, Gainesville, FL 32611-2055 (United States); Schmitt, B. M.; Pavlov, G. G. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab., University Park, PA 16802 (United States); Misanovic, Z. [School of Physics, Monash University, Melbourne, 3800 VIC (Australia)

2012-01-20

328

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

CERN Document Server

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

Völk, H J; Ksenofontov, L T

2004-01-01

329

ROSAT/Asca Observations of the Mixed-Morphology Supernova Remnant W28  

CERN Document Server

We present ROSAT PSPC and ASCA observations of the supernova remnant (SNR) W28. The overall shape of X-ray emission in W28 is elliptical, dominated by a centrally-concentrated interior emission, sharply peaked at the center. The ASCA spectra reveal emission lines of Ne, Mg, Si, and Fe K$\\alpha$ and continuum extending at least up to 7 keV, showing thermal origin with a hot thermal component. We found that spectral variations are present in W28. The southwestern shell can be fit well by a plane-shock model with a temperature of 1.5 keV, and the northeastern shell, with a lower temperature of 0.56 keV. Unlike for the southwestern and northeastern shells, the central emission requires a two-temperature components with 0.6 keV and 1.8 keV. The low temperature component is similar to those seen in other Mixed-morphology SNRs. The X-ray luminosity of W28 is 6x 10^34 ergs/s, and the estimated X-ray mass is only ~20 - 25 solar mass. A comparison of W28 with other typical Mixed-morphology SNRs reveals significant diff...

Rho, J; Rho, Jeonghee; Borkowski, Kazimierz J.

2002-01-01

330

The Interaction of Supernova Remnant G357.7+0.3 with the Interstellar Medium  

CERN Document Server

The supernova remnant (SNR) G357.7+0.3 appears to have caused considerable shredding of the local interstellar medium (ISM), leading to the formation of multiple cloud fragments having bright rims and cometary structures. We investigate five of these regions using mid-infrared (MIR) imaging and photometry deriving from the Spitzer Space Telescope (SST), as well as photometry deriving from the 2MASS near-infrared all sky survey, the Mid-Course Science Experiment (MSX), and the Multiband Imaging Photometer for Spitzer (MIPSGAL) survey of the Galactic plane. It is noted that two of the rims show evidence for emission by shock excited H2 transitions, whilst the centres of the clouds also show evidence for dark extinction cores, observed in silhouette against the bright emission rims. Levels of extinction for these cores are determined to be of order AV ~ 17-26 mag, whilst densities n(HI) are of order ~ 10^4 cm^(-3), and masses in the region of ~40-100 Msun. It is shown that the wavelength dependence of extinction...

Phillips, J P; 10.1111/j.1365-2966.2010.17340.x

2010-01-01

331

Systematic search for gamma-ray emitting molecular clouds in the vicinity of supernova remnants  

CERN Document Server

Observations of very-high-energy (VHE) gamma-ray emission from supernova remnants (SNR) established them as sources of accelerated particles up to energies of 100 TeV. The dominant process - leptonic or hadronic - responsible for the VHE emission is still not proven for most of the SNRs. Molecular clouds (MCs) in the vicinity of SNRs provide increased amount of target material for accelerated particles escaping the SNRs, thus making MCs potential gamma-ray sources. The predicted gamma-ray flux for MCs offset from the SNR shock depends on the applied diffusion model for VHE particles and the SNR and MC properties, which encounter large uncertainties. While the the average galactic diffusion coefficient is estimated, the spatially resolved propagation properties of VHE cosmic rays are unknown. gamma-ray emitting MCs provide a unique possibility to derive new information on the propagation of VHE particles through the ISM and on the acceleration of hadrons at SNRs. We present in this paper a strategy and first r...

Häffner, Stephanie; Stegmann, Christian

2013-01-01

332

Gamma-rays from molecular clouds illuminated by accumulated diffusive protons. II: interacting supernova remnants  

CERN Document Server

Recent observations reveal that spectral breaks at ~ GeV are commonly present in Galactic gamma-ray supernova remnants (SNRs) interacting with molecular clouds and that most of them have a spectral ($E^2dF/dE$) "platform" extended from the break to lower energies. In paper I (Li & Chen 2010), we developed an accumulative diffusion model by considering an accumulation of the diffusive protons escaping from the shock front throughout the history of the SNR expansion. In this paper, we improve the model by incorporating finite-volume of MCs and apply it to nine interacting SNRs (W28, W41, W44, W49B, W51C, Cygnus Loop, IC443, CTB 37A, and G349.7+0.2). This refined model naturally explains the GeV spectral breaks and, especially, the "platform"s, together with available TeV data. We find that the diffusion coefficient for cosmic rays around the SNRs is essentially two orders of magnitude lower than the Galactic average, which is a good indication for the suppression of cosmic ray diffusion near SNRs.

Li, Hui

2011-01-01

333

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

CERN Document Server

Context. Supernova Remnants (SNRs) are thought to be the main source of Galactic cosmic rays (CRs) up to the "knee". During the evolution of a SNR, the bulk of the CRs are confined within the SNR shell. The highest-energy particles leave the system continuously, while the remaining adiabatically-cooled particles are released when the SNR has sufficiently expanded and slowed down so that the magnetic field (MF) at the shock is no longer able to confine them. Particles escaping from the parent system may end up interacting with nearby molecular clouds (MCs), producing $\\gamma$-rays in the process via pion decay. The soft gamma-ray spectra observed from a number of SNRs interacting with molecular clouds (MCs) however challenge current theories of non-linear particle acceleration that predict harder spectra. Aims. To study how the spectrum of escaped particles depends on the time-dependent acceleration history in both type-Ia and core-collapse SNRs, as well as on different assumptions about the diffusion coeffici...

Telezhinsky, I; Pohl, M

2011-01-01

334

On the size distribution of supernova remnants in the Magellanic Clouds  

CERN Document Server

The physical sizes of supernova remnants (SNRs) in a number of nearby galaxies follow an approximately linear cumulative distribution, contrary to what is expected for decelerating shock fronts. This has been attributed to selection effects, or to a majority of SNRs propagating in "free expansion", at constant velocity, into a tenuous ambient medium. We compile a list of 77 known SNRs in the Magellanic Clouds (MCs), and argue that they are a largely complete record of the SNe that have exploded over the last ~20kyr, with most now in the adiabatic, Sedov phase of their expansions. The roughly linear cumulative size distribution (uniform in a differential distribution) can result from the combination of a deceleration during this phase, a transition to a radiation-loss-dominated phase at a radius that depends on the local gas density, and a distribution of ambient densities varying roughly as rho^{-1}. This explanation is supported by the observed -1 power-law distributions of three independent tracers of densi...

Badenes, Carles; Draine, Bruce

2010-01-01

335

An interpretation of the overionized plasma in supernova remnant W49B  

Science.gov (United States)

W49B is a mixed-morphology supernova remnant (SNR) with the presence of enhanced abundances and overionization confirmed by X-ray observation. For the overionization, a strong radiative recombination continuum (RRC) has been detected and confirmed by SUZAKU and XMM-Newton. Here, we investigate these intriguing observational results through a multidimensional hydrodynamic model that takes into account, for the first time, the mixing of ejecta with the circumstellar and interstellar medium, thermal conduction, and non-equilibrium ionization. The model can reproduce the morphology and the overionization pattern of W49B. We found that the overionized plasma originates from the rapid cooling of the hot plasma originally heated by the shock reflected from the dense ring-like cloud. In addition, based on the most updated ATOMDB (v2.0.2), we calculated the spectrum of one cell in the overionized region from the simulation results at present. We got the overionized spectrum that is in agreement with the observational results. Thus, our primary result indicates that the model is consistent with the observations both spatially and spectrally.

Zhou, Xin; Miceli, Marco; Bocchino, Fabrizio; Orlando, Salvatore; Chen, Yang; Ji, Li; Yang, Ji

2014-01-01

336

Neutral pion emission from accelerated protons in the supernova remnant W44  

CERN Document Server

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

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

2011-01-01

337

Dust Destruction in Type Ia Supernova Remnants in the Large Magellanic Cloud  

CERN Document Server

We present first results from an extensive survey of Magellanic Clouds supernova remnants (SNRs) with the Spitzer Space Telescope. We describe IRAC and MIPS imaging observations at 3.6, 4.5, 5.8, 8, 24, and 70 microns of four Balmer-dominated Type Ia SNRs in the Large Magellanic Cloud (LMC): DEM L71 (0505-67.9), 0509--67.5, 0519--69.0, and 0548-70.4. None was detected in the four short-wavelength IRAC bands, but all four were clearly imaged at 24 microns, and two at 70 microns. A comparison of these images to Chandra broadband X-ray images shows a clear association with the blast wave, and not with internal X-ray emission associated with ejecta. Our observations are well described by 1-D shock models of collisionally heated dust emission, including grain size distributions appropriate for the LMC, grain heating by collisions with both ions and electrons, and sputtering of small grains. Model parameters are constrained by X-ray, optical, and far-ultraviolet observations. Our models can reproduce observed 70/24...

Borkowski, K J; Reynolds, S P; Blair, W P; Ghavamian, P; Sankrit, R; Hendrick, S P; Long, K S; Raymond, J C; Smith, R C; Points, S; Winkler, P F; Borkowski, Kazimierz J.; Williams, Brian J.; Reynolds, Stephen P.; Blair, William P.; Ghavamian, Parviz; Sankrit, Ravi; Hendrick, Sean P.; Long, Knox S.; Raymond, John C.; Points, Sean

2006-01-01

338

News from Supernova Remnants and Pulsar Wind Nebulae in the TeV Band  

Science.gov (United States)

VERITAS is an array of four atmospheric Cherenkov telescopes located in Southern Arizona and is sensitive to gamma rays above 100 GeV. Here we highlight recent VERITAS studies of supernova remnants and pulsar wind nebulae. The results provide constraints on competing particle acceleration emission models within these complex environments.

Humensky, Brian

2014-08-01

339

Discrete sources of gamma radiation, supernova remnants and pulsars  

International Nuclear Information System (INIS)

An attempt to identify detected by present discrete gamma radiation sources (Esub(?) approximately equal to 108 eV) with known residuals of supernova flares is undertaken. An analysis of gamma source catalogue shows that most part (70%) of detected discrete gamma radiation sources may be identified with known residuals of sUpernova flares. Supernova residuals being identified have a low spectral index ? < or approximately 0.3. Such objects, probably, contain a pulsar with a relatively large magnetic field. It is possible that supernovae 185g and 393g are related to gamma sources. There are not less than 150 similar gamma sources in Galaxy which contribute significantly into diffuse gamma radiation of a galactic disc

340

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

CERN Document Server

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

Pan, Kuo-Chuan; Taam, Ronald

2013-01-01

 
 
 
 
341

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

CERN Document Server

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

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

2004-01-01

342

Kinematics of the Galactic Supernova Remnant G206.9+2.3  

Science.gov (United States)

We studied the kinematics of the galactic supernova remnant (SNR) G206.9+2.3 (PKS 0646+06) in the [SII] &?; 6717 and 6731 Å lines, as one of the initial steps of a long-term project to determine kinematical distances to galactic SNRs with optical counterparts. We obtained the kinematic distance to this nebula by first showing that the filaments detected were in fact the optical counterpart of the radio SNR. The distance estimated here is slightly greater than that of the Monoceros Loop. We estimate that G206.9+2.3 is located about 2.2 kpc from the Sun, in a zone where several background and foreground nebulae at different velocities are seen in projection. We measured a shock velocity of 86 km s^{-1} and a linear diameter of 18 pc. Finally, we calculated the energy deposited in the interstellar medium by the SN explosion as 1.7×10^{49} ergs and concluded that the SNR is in the radiative phase of evolution with an age of 6.4×10^{4} years. %Z Brand, J., & Blitz, L. 1993, A&A, 275, 67 Caswell, J. L. 1970, Australian J. Phys., 23, 105 Davies, R. D., & Meaburn, J. 1978, A&A, 69, 443 Day, G., Caswell, J., & Cooke, D. 1972, Australian J. Phys. Astrophys. Supp., 25, 1 Gao, X. Y., Han, J. L., Reich, W., Reich, P., Sun, X. H. & Xiao L. 2011, A&A, 529, 159 Graham, D. A., Haslam, C. G. T., Salter C. J. & Wilson W.E. 1982, A&A, 109, 145 Green, D.A. 2009, A Catalogue of Galactic Supernova Remnants, available online at http://www.mrao.cam.ac.uk/surveys/snrs/ Haslam, C. G. T., & Salter, C. J. 1971, MNRAS, 151, 385 Holden, D. J. 1968, MNRAS, 141, 57 Leahy, D. A. 1986, A&A, 156, 191 Le Coarer, E., Rosado, M., Georgelin, Y., et al. 1993, A&A, 280, 365 Lozinskaya, T. A. 1972, Soviet Astron., 15, 910 Rosado, M. 1982, ReMexAA, 5, 127 Rosado, M., Langarica, R., Bernal, A. et al. 1995, ReMexAA(SC), 3,268 Rosado, M., Ambrocio-Cruz, P., LeCoarer, E., & Marcelin, M. 1996, A&A, 315, 243 Stupar, M., & Parker, Q. A. 2011, MNRAS, 414, 2282 van den Bergh, S. 1978, ApJ, 220, 171

Ambrocio-Cruz, P.; Rosado, M.; Le Coarer, E.; Bernal, A.; Gutiérrez, L.

2014-10-01

343

Interpretation of the number versus diameter distribution for supernova remnants in the Large Magellanic Cloud  

Science.gov (United States)

An examination is conducted of the cumulative number versus diameter relation for an X-ray selected sample of supernova remnants in the Large Magellanic Cloud in an attempt to understand the evolutionary state of these objects. Previous studies have suggested that the observed linear N(D) relation requires the remnants in the cloud to be freely expanding. Detailed calculations have been carried out to determine the effect of a luminosity threshold on the observed distribution and it is shown that the observations can be fitted by remnants which are in the adiabatic or later stages of evolution. The implications of the results for the supernova creation rate in the LMC are discussed.

Hughes, J. P.; Helfand, D. J.; Kahn, S. M.

1984-01-01

344

How Do The Properties of Light Help Us To Study Supernovae and Their Remnants?  

Science.gov (United States)

This resource describes special properties of light that can help us to understand objects that are millions and billions of light years away. Students explore some of these properties and how they can use them to understand our universe. They will understand that superheated material created by the supernova explosion gives off X-rays and gamma-rays. They will find the answers to questions such as what electromagnetic (EM) radiation is and what units are used to characterize it. They also learn that it pays to make multiple observations of astronomical objects, since they emit light of different energies, that supernovae remnants can give off visible light, ultraviolet light, radio waves and X-rays, and that each observation of a supernovae remnant can give us different information about it. The site also includes a student exercise and links to more information.

345

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

International Nuclear Information System (INIS)

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

346

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

International Nuclear Information System (INIS)

A rapidly growing amount of evidences, mostly coming from the recent gamma-ray observations of Galactic supernova remnants (SNRs), is seriously challenging our understanding of how particles are accelerated at fast shocks. The cosmic-ray (CR) spectra required to account for the observed phenomenology are in fact as steep as E?2.2–E?2.4, i.e., steeper than the test-particle prediction of first-order Fermi acceleration, and significantly steeper than what expected in a more refined non-linear theory of diffusive shock acceleration. By accounting for the dynamical back-reaction of the non-thermal particles, such a theory in fact predicts that the more efficient the particle acceleration, the flatter the CR spectrum. In this work we put forward a self-consistent scenario in which the account for the magnetic field amplification induced by CR streaming produces the conditions for reversing such a trend, allowing — at the same time — for rather steep spectra and CR acceleration efficiencies (about 20%) consistent with the hypothesis that SNRs are the sources of Galactic CRs. In particular, we quantitatively work out the details of instantaneous and cumulative CR spectra during the evolution of a typical SNR, also stressing the implications of the observed levels of magnetization on both the expected maximum energy and the predicted CR acceleration efficiency. The latter naturally turns out to saturate around 10-30%, almost independently of the fraction of particles injected into the acceleration process as long as this fraction is larger than about 10?4

347

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

CERN Document Server

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

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

2011-01-01

348

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

CERN Document Server

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

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

2010-01-01

349

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

International Nuclear Information System (INIS)

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

350

Star Formation Around the Youngest Supernova Remnants in the Large Magellanic Cloud: Implications for Type Ia Supernova Progenitors  

Science.gov (United States)

We use the star formation history map of the Large Magellanic Cloud recently published by Harris & Zaritsky to study the sites of the four smallest (and presumably youngest) Type Ia supernova remnants: 0509-67.5, 0519-69.0, N103B and DEM L71. We find that three of the four Type Ia remnants are associated with old, metal-poor stellar populations, with little or no recent star formation. These include SNR 0509-67.5 which is known to have been originated by an extremely bright SN 1991 T-like event, and yet is located very far away from any star forming regions. It is very unlikely that this bright Type Ia SN had a young stellar progenitor. The fourth Type Ia remnant, SNR N103B is associated with vigorous star formation activity in the last 100 Myr, and might have had a relatively younger and more massive progenitor.

Badenes, Carles; Harris, Jason; Zaritsky, Dennis; Prieto, José Luis

2009-05-01

351

Star Formation Around the Youngest Supernova Remnants in the Large Magellanic Cloud: Implications for Type Ia Supernova Progenitors  

CERN Document Server

We use the star formation history map of the Large Magellanic Cloud recently published by Harris & Zaritsky to study the sites of the youngest Type Ia supernova remnants. We find that most Type Ia remnants are associated with old, metal-poor stellar populations, with little or no recent star formation. These include SNR 0509-67.5 which is known to have been originated by an extremely bright SN 1991T-like event, and yet is located very far away from any star forming regions. The Type Ia remnant SNR N103B, however, is associated with vigorous star formation activity in the last 100 Myr, and might have had a relatively younger and more massive progenitor.

Badenes, Carles; Zaritsky, Dennis; Prieto, Jose Luis

2009-01-01

352

Identification campaign of supernova remnant candidates in the Milky Way. II. X-ray studies of G38.7-1.4  

CERN Document Server

We report on XMM-Newton and Chandra observations of the Galactic supernova remnant candidate G38.7-1.4, together with complementary radio, infrared, and gamma-ray data. An approximately elliptical X-ray structure is found to be well correlated with 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 behaviour, we suggest that G38.7-1.4 is indeed a supernova remnant belongs to a mix-morphology category.

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

2014-01-01

353

A high-resolution radio survey of the Vela supernova remnant  

CERN Document Server

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

Bock, D; Green, A J

1998-01-01

354

Four new X-ray-selected supernova remnants in the Large Magellanic Cloud  

CERN Document Server

Aims: We present a detailed multi-wavelength study of four new supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). The objects were identified as SNR candidates in X-ray observations performed during the survey of the LMC with XMM-Newton. Methods: Data obained with XMM-Newton are used to investigate the morphological and spectral features of the remnants in X-rays. We measure the plasma conditions, look for supernova (SN) ejecta emission, and constrain some of the SNR properties (e.g. age and ambient density). We supplement the X-ray data with optical, infrared, and radio-continuum archival observations, which allow us to understand the conditions resulting in the current appearance of the remnants. Based on the spatially-resolved star formation history (SFH) of the LMC together with the X-ray spectra, we attempt to type the supernovae that created the remnants. Results: We confirm all four objects as SNRs, to which we assign the names MCSNR J0508-6830, MCSNR J0511-6759, MCSNR J0514-6840, and MCSNR...

Maggi, P; Kavanagh, P J; Points, S D; Dickel, J; Bozzetto, L M; Sasaki, M; Chu, Y -H; Gruendl, R A; Filipovic, M D; Pietsch, W

2013-01-01

355

The Youngest Known X-ray Binary: Circinus X-1 and its Natal Supernova Remnant  

CERN Document Server

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 < 4, 600 years on its age, making it the youngest known X-ray binary and a unique tool to study accretion, neutron star evolution, and core collapse supernovae. This discovery is based on a deep 2009 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 which we...

Heinz, S; 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

2013-01-01

356

Swift/BAT detection of hard X-rays from Tycho's Supernova Remnant: Evidence for Titanium-44  

CERN Document Server

We report Swift/BAT survey observations of the Tycho's supernova remnant, performed over a period of 104 months since the mission's launch. The remnant is detected with high significance (>10 sigma) below 50 keV. We detect significant hard X-ray emission in the 60-85 keV band, above the continuum level predicted by a simple synchrotron model. The location of the observed excess is consistent with line emission from radioactive Titanium-44, so far reported only for Type II supernova explosions. We discuss the implications of these results in the context of the galactic supernova rate, and nucleosynthesis in Type Ia supernova.

Troja, E; La Parola, V; Hartmann, D; Baumgartner, W; Markwardt, C; Barthelmy, S; Cusumano, G; Gehrels, N

2014-01-01

357

A Deep Chandra Observation of the Oxygen-Rich Supernova Remnant 0540-69.3 in the Large Magellanic Cloud  

CERN Document Server

Using our deep ~120 ks Chandra observation, we report on the results from our spatially-resolved X-ray spectral analysis of the "oxygen-rich" supernova remnant (SNR) 0540-69.3 in the Large Magellanic Cloud. We conclusively establish the nonthermal nature of the "arcs" in the east and west boundaries of the SNR, which confirms the cosmic-ray electron acceleration in the supernova shock (B ~ 20-140 microG). We report tentative evidence for Fe overabundance in the southern region close to the outer boundary of the SNR. While such a detection would be intriguing, the existence of Fe ejecta is not conclusive with the current data because of poor photon statistics and limited plasma models. If it is verified using deeper X-ray observations and improved plasma models, the presence of Fe ejecta, which was produced in the core of the supernova, near the SNR's outer boundary would provide an intriguing opportunity to study the explosive nucleosynthesis and the ejecta mixing in this young core-collapse SNR. There is no ...

Park, Sangwook; Slane, Patrick O; Mori, Koji; Burrows, David N

2009-01-01

358

Study on The Difference Between Proper-Motion of Halpha line emission and Non-Thermal X-Ray emission In Supernova Remnants  

Science.gov (United States)

Balmer line emission (Halpha) by neutral hydrogen and X-ray synchrotron emission by accelerated electrons are observed from some supernova remnants (SNRs), which are thought as accelerators of galactic cosmic rays (CRs). From these observations, the cosmic ray acceleration efficiency is estimated. According to the theory of diffusive shock acceleration (DSA), electrons are accelerated around the shock front, and emit the synchrotron radiation. Measurement of proper motion of the synchrotron X-rays gives the shock velocity. At the same time, we can estimate the post shock temperature from the line width of Halpha emission, because neutral hydrogen collide with downstream hot protons and exchange their charge, so that the hot neutral component arises. In the specific case of a SNR RCW86, measured expansion speed of Halpha filament is about 1200km/s (Helder et al. 2013), while 6000km/s in X-rays (Helder et al. 2009). It is expected that the emission regions of the Halpha and the synchrotron X-rays are different. However, they are overlaid in the same line of sight. In this study, using three dimensional magnetohydrodynamics (MHD) simulations, we consider propagation of supernova blast wave shock in realistic inhomogeneous interstellar medium. Interaction between the upstream density inhomogeneity and the shock wave causes rippled shock structure and fluctuation of local shock velocity.We show that our synthetic observations of the MHD simulation data are consistent with actual observation results for RCW86.

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

359

Near-infrared [Fe II] emission from supernova remnants and the supernova rate of starburst galaxies  

CERN Document Server

In an effort to better calibrate the supernova rate of starburst galaxies as determined from near-IR [Fe II] features, we report on a [Fe II] 1.644 microns line-imaging survey of a sample of 42 optically-selected SNRs in M33. A wide range of [Fe II] luminosities are observed within our sample (from less than 6 to 695 L_sun). Our data suggest that the bright [Fe II] SNRs are entering the radiative phase and that the density of the local ISM largely controls the amount of [Fe II] emission. We derive the following relation between the [Fe II] 1.644 microns line luminosity of radiative SNRs and the electronic density of the postshock gas, n_e: L_[Fe II] (L_sun) ~ 1.1 n_e (cm^-3). We also find a correlation in our data between L_[Fe II] and the metallicity of the shock-heated gas, but the physical interpretation of this result remains inconclusive, as our data also show a correlation between the metallicity and n_e. The dramatically higher level of [Fe II] emission from SNRs in the central regions of starburst gal...

Morel, T; Saint-Louis, N

2002-01-01

360

3D Simulations of the Thermal X-ray Emission from Young Supernova Remnants Including Efficient Particle Acceleration  

CERN Document Server

Supernova remnants (SNRs) are believed to be the major contributors to Galactic cosmic rays. The detection of non-thermal emission from SNRs demonstrates the presence of energetic particles, but direct signatures of protons and other ions remain elusive. If these particles receive a sizeable fraction of the explosion energy, the morphological and spectral evolution of the SNR must be modified. To assess this, we run 3D hydrodynamic simulations of a remnant coupled with a non-linear acceleration model. We obtain the time-dependent evolution of the shocked structure, impacted by the Rayleigh-Taylor hydrodynamic instabilities at the contact discontinuity and by the back-reaction of particles at the forward shock. We then compute the progressive temperature equilibration and non-equilibrium ionization state of the plasma, and its thermal emission in each cell. This allows us to produce the first realistic synthetic maps of the projected X-ray emission from the SNR. Plasma conditions (temperature, ionization age) ...

Ferrand, Gilles; Safi-Harb, Samar

2012-01-01

 
 
 
 
361

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

CERN Document Server

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

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

2008-01-01

362

A multi-wavelength study of Supernova Remnants in six nearby galaxies. I: Detection of new X-ray selected Supernova Remnants with Chandra  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present results from a study of the Supernova Remnant (SNR) population in a sample of six nearby galaxies (NGC 2403, NGC 3077, NGC 4214, NGC 4449, NGC 4395 and NGC 5204) based on Chandra archival data. We have detected 244 discrete X-ray sources down to a limiting flux of 10^{-15} erg/s. We identify 37 X-ray selected thermal SNRs based on their X-ray colors or spectra, 30 of which are new discoveries. In many cases the X-ray classification is confirmed based on counterpar...

Leonidaki, Ioanna; Zezas, Andreas; Boumis, Panayotis

2010-01-01

363

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

Directory of Open Access Journals (Sweden)

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

R. J. Garc\\u00EDa L\\u00F3pez

2009-01-01

364

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

CERN Document Server

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

Chen, W; Chen, Wan

1998-01-01

365

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

Science.gov (United States)

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

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

2010-02-26

366

Cosmic rays of leptons from Pulsars and Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The latest results from PAMELA and FERMI experiments confirm the necessity to improve theoretical models of production and propagation of galactic electrons and positrons. There are many possible explanations for the positron excess observed at energies larger than 10 GeV and for some features around 1 TeV in the total flux of electrons and positrons. Supernovae are astrophysical objects with the potential to explain these observations. In this work, we present an updated st...

Lineros, Roberto A.

2010-01-01

367

X-Ray Observations of the supernova remnant G21.5-0.9  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the analysis of archival X-ray observations of the supernova remnant (SNR) G21.5-0.9. Based on its morphology and spectral properties, G21.5-0.9 has been classified as a Crab-like SNR. In their early analysis of the CHANDRA calibration data, Slane et al. (2000) discovered a low-surface-brightness, extended emission. They interpreted this component as the blast wave formed in the supernova (SN) explosion. In this paper, we present the CHANDRA analysis using a total...

Safi-harb, S.; Harrus, I. M.; Petre, R.; Pavlov, G. P.; Koptsevich, A. B.; Sanwal, D.

2001-01-01

368

A new candidate supernova remnant G 70.5+1.9  

CERN Document Server

A compact complex of line emission filaments in the galactic plane has the appearance of those expected of an evolved supernova remnant though non-thermal radio and X-ray emission have not yet been detected. This optical emission line region has now been observed with deep imagery and both low and high-dispersion spectroscopy. Diagnostic diagrams of the line intensities from the present spectra and the new kinematical observations both point to a supernova origin. However, several features of the nebular complex still require an explanation within this interpretation.

Mavromatakis, F; Meaburn, J; Caulet, A

2009-01-01

369

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

Energy Technology Data Exchange (ETDEWEB)

The discovery of bright gamma-ray emission coincident with supernova remnant (SNR) W51C is reported using the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. W51C is a middle-aged remnant ({approx}10{sup 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 1 x 10{sup 36} erg s{sup -1} 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 p mesons produced in hadronic collisions provides a plausible explanation for the gamma-ray emission. The product of the average gas density and the total energy content of the accelerated protons amounts to {bar n}{sub H} W{sub p} {approx_equal} 5 x 10{sup 51} (D/6 kpc){sup 2} erg cm{sup -3}. Electron density constraints from the radio and X-ray bands render it difficult to explain the LAT signal as due to inverse Compton scattering. The Fermi LAT source coincident with SNR W51C sheds new light on the origin of Galactic cosmic rays.

Abdo, A.A.; /Naval Research Lab, Wash., D.C. /Federal City Coll.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, G.; /INFN, Trieste /Trieste U.; Baring, M.G.; /Rice U.; Bastieri, D.; /INFN, Padua /Padua U.; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Blandford, R.D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, E.D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bouvier, A.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique /Washington U., Seattle /Padua U. /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /IASF, Milan /Milan Polytechnic /DAPNIA, Saclay /INFN, Perugia /Perugia U. /NASA, Goddard /NASA, Goddard /CSST, Baltimore /Naval Research Lab, Wash., D.C. /George Mason U. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Montpellier U. /Sonoma State U. /Stockholm U. /Stockholm U., OKC /ASDC, Frascati /Naval Research Lab, Wash., D.C. /INFN, Trieste /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Montpellier U. /Bari U. /INFN, Bari /Ecole Polytechnique /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Ecole Polytechnique; /more authors..

2012-03-30

370

ON THE RADIO POLARIZATION SIGNATURE OF EFFICIENT AND INEFFICIENT PARTICLE ACCELERATION IN SUPERNOVA REMNANT SN 1006  

Energy Technology Data Exchange (ETDEWEB)

Radio polarization observations provide essential information on the degree of order and orientation of magnetic fields, which themselves play a key role in the particle acceleration processes that take place in supernova remnants (SNRs). Here we present a radio polarization study of SN 1006, based on combined Very Large Array and Australia Telescope Compact Array observations at 20 cm that resulted in sensitive images with an angular resolution of 10 arcsec. The fractional polarization in the two bright radio and X-ray lobes of the SNR is measured to be 0.17, while in the southeastern sector, where the radio and non-thermal X-ray emission are much weaker, the polarization fraction reaches a value of 0.6 {+-} 0.2, close to the theoretical limit of 0.7. We interpret this result as evidence of a disordered, turbulent magnetic field in the lobes, where particle acceleration is believed to be efficient, and a highly ordered field in the southeast, where the acceleration efficiency has been shown to be very low. Utilizing the frequency coverage of our observations, an average rotation measure of {approx}12 rad m{sup -2} is determined from the combined data set, which is then used to obtain the intrinsic direction of the magnetic field vectors. While the orientation of magnetic field vectors across the SNR shell appear to be radial, a large fraction of the magnetic vectors lie parallel to the Galactic plane. Along the highly polarized southeastern rim, the field is aligned tangent to the shock, and therefore also nearly parallel to the Galactic plane. These results strongly suggest that the ambient field surrounding SN 1006 is aligned with this direction (i.e., from northeast to southwest) and that the bright lobes are due to a polar cap geometry. Our study establishes that the most efficient particle acceleration and generation of magnetic turbulence in SN 1006 is attained for shocks in which the magnetic field direction and shock normal are quasi-parallel, while inefficient acceleration and little to no generation of magnetic turbulence are obtained for the quasi-perpendicular case.

Reynoso, Estela M. [Instituto de Astronomia y Fisica del Espacio (IAFE), C. C. 67, Suc. 28, 1428 Buenos Aires (Argentina); Hughes, John P. [Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854-8019 (United States); Moffett, David A., E-mail: ereynoso@iafe.uba.ar, E-mail: jph@physics.rutgers.edu, E-mail: david.moffett@furman.edu [Department of Physics, Furman University, Greenville, SC 29613 (United States)

2013-04-15

371

A kinetic approach to cosmic ray induced streaming instability at supernova shocks  

Energy Technology Data Exchange (ETDEWEB)

We show here that a purely kinetic approach to the excitation of waves by cosmic rays in the vicinity of a shock front leads to predict the appearance of a non-alfvenic fastly growing mode which has the same dispersion relation as that previously found by Bell (2004) by treating the plasma in the MHD approximation. The kinetic approach allows us to investigate the dependence of the dispersion relation of these waves on the microphysics of the current which compensates the cosmic ray flow. We also show that a resonant and a non-resonant mode may appear at the same time and one of the two may become dominant on the other depending on the conditions in the acceleration region. We discuss the role of the unstable modes for magnetic field amplification and particle acceleration in supernova remnants at different stages of the remnant evolution.

Amato, Elena; /Arcetri Observ.; Blasi, Pasquale; /Arcetri Observ. /Fermilab /Gran Sasso

2008-06-01

372

Non-thermal emission in astrophysical environments: From pulsars to supernova remnants  

Science.gov (United States)

The study of electromagnetic radiation from distant astrophysical objects provides essential data in understanding physics of these sources. In particular, non-thermal radiation provides great insight into the properties of local environments, particle populations, and emission mechanisms, knowledge which otherwise would remain untapped. Throughout the projects conducted for this dissertation, we modeled certain aspects of observed non-thermal emission from three classes of sources: radio pulsars, pulsar wind nebulae, and supernova remnants. Orbital variation in the double pulsar system PSR J0737-3039A/B can be used to probe the details of the magnetospheric structure of pulsar B. Strongly magnetized wind from pulsar A distorts the magnetosphere of pulsar B in a way similar to the solar wind's distortion of the Earth's magnetosphere. Using the two complimentary models of pulsar B's magnetosphere, adapted from the Earth's magnetosphere models by Dungey and Tsyganenko, we determine the precise location of the coherent radio emission generation region in pulsar B's magnetosphere. This analysis is complemented by modeling the observed evolution of the pulse profiles of B due to geodetic precession. The emission region is located at about 3750 stellar radii and has a horseshoe-like shape centered on the polar magnetic field lines. The best fit angular parameters of the emission region indicate that radio emission is generated on the field lines which, according to the theoretical models, originate close to the poles and carry the maximum current. When considered together, not only do the results of the two models converge, they can explain why the modulation of B's radio emission at A's period is observed only within a certain orbital phase region. We discuss the implications of these results for pulsar magnetospheric models and mechanisms of coherent radio emission generation. We also developed a spatially-resolved, analytic model for the high-energy non-thermal emission from pulsar wind nebulae (PWNe). Theoretically, synchrotron cooling should cause a gradual change in particle spectrum downstream. This effect is indeed observed in the X-ray spectra of The Crab Nebula , 3C 58, and G21.5.0.9. However, current theoretical models of PWNe that only account for the bulk motion in the pulsar outflow overestimate the steepening of the resulted emission spectrum. This implies that there is an additional mechanism of particle transport which would supply energetic particles to the outer layers of the PWN. Our model solves the lack of high-energy electrons in the outer regions of the nebula by taking the diffusion of particles into account. The resulting multi-wavelength spectra exhibits multiple breaks, which is in agreement with observations. Thin non-thermal X-ray filaments are often seen near shock fronts in young supernova remnants (SNRs), often spatially coincident with the high energy gamma-ray emission. The formation of such discrete features is likely influenced by the combined effects of radiative cooling, advection, and diffusion. Spatially-resolved spectral studies of the filaments may, therefore, provide significant insights into the relative importance of main physical processes involved in young SNRs. Using 1 Ms Chandra observation of Cassiopeia A, we perform advection-diffusion modeling of synchrotron emission of filaments to measure the magnetic field, shock obliquity, the diffusion strength and the plasma turbulence level.

Lomiashvili, David

373

Neutral hydrogen in the vicinity of galactic radio sources: the supernova remnant W44  

International Nuclear Information System (INIS)

The H I radio line has been observed in absorption and emission near the source W44 with the RATAN-600 radio telescope at 2'.2 x 20' x 6.3 km/sec resolution. The absorption-line observations show that the nearby H II region NRAO 584 cannot be physically associated with the supernova remnant. The six H I clouds detected in emission and absorption may possibly form part of a patchy envelope around W44; three of them coincide with a molecular cloud in the vicinity. The combined mass of the H I clouds is roughly-equal220 M/sub sun/, and if the envelope is real it would be expanding at roughly-equal10 km/sec. Estimates are obtained for the age of the supernova remnant and the physical parameters of NRAO 584

374

Does the galactic synchrotron radio background originate in old supernova remnants  

International Nuclear Information System (INIS)

Observations of the galactic synchrotron radio background indicate that the emission arises in localized regions of high emissivity. Various lines of evidence suggest that these are the radiative shells of old supernova remnants in which the synchrotron emissivity is enhanced due to compression of the interstellar magnetic field along with the correlated increase in the energy density of cosmic ray electrons. This possibility is consistent with recent observations of the interstellar medium that imply the presence of a large amount of hot, low density gas in the galaxy. In such a medium supernova remnants would expand to large radii before becoming radiative. The intensity of the background can then be understood without needing to evoke higher magnetic fields or cosmic ray electron fluxes than are obtained from other observations. In this picture, the fluctuating component of the galactic magnetic field arises from the distortion of the regular field by the shells. (author)

375

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

International Nuclear Information System (INIS)

The H I line in the vicinity of the radio source W28 has been observed in absorption and emission with the RATAN-600 radio telescope at a resolution of 2'.4 x 45' x 6.3 km/sec. The absorption line yields a distance of roughly-equal3 kpc to the supernova remnant; the compact H II regions observed there are located at the same distance. In emission, an expanding H I envelope 82 pc in diameter has been detected around W28; its mass is 6.9 x 104 M/sub sun/ and it is expanding at roughly-equal20 km/sec. The supernova remnant is 5.8 x 105 yr old and the energy of the original explosion was 8.4 x 1051 erg. Some conclusions are reached as to the possible genetic relation between the H II zones and the SNR

376

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

Science.gov (United States)

We present Spitzer MIPS SED and IRS observations of 14 Galactic Supernova Remnants previously identified in the GLIMPSE survey. We find evidence for SNR/molecular cloud interaction through detection of [OI] emission, ionic lines, and emission from molecular hydrogen. Through black-body fitting of the MIPS SEDs we find the large grains to be warm, 29-66 K. The dust emission is modeled using the DUSTEM code and a three component dust model composed of populations of big grains, very small grains, and polycyclic aromatic hydrocarbons. We find the dust to be moderately heated, typically by 30-100 times the interstellar radiation field. The source of the radiation is likely hydrogen recombination, where the excitation of hydrogen occurred in the shock front. The ratio of very small grains to big grains is found for most of the molecular interacting SNRs to be higher than that found in the plane of the Milky Way, typically by a factor of 2--3. We suggest that dust shattering is responsible for the relative over-abundance of small grains, in agreement with prediction from dust destruction models. However, two of the SNRs are best fit with a very low abundance of carbon grains to silicate grains and with a very high radiation field. A likely reason for the low abundance of small carbon grains is sputtering. We find evidence for silicate emission at 20 $\\mu$m in their SEDs, indicating that they are young SNRs based on the strong radiation field necessary to reproduce the observed SEDs.

Hewitt, John W.; Petre, Robert; Katsuda Satoru; Andersen, M.; Rho, J.; Reach, W. T.; Bernard, J. P.

2011-01-01

377

Cosmic rays of leptons from Pulsars and Supernova Remnants  

CERN Document Server

The latest results from PAMELA and FERMI experiments confirm the necessity to improve theoretical models of production and propagation of galactic electrons and positrons. There are many possible explanations for the positron excess observed at energies larger than 10 GeV and for some features around 1 TeV in the total flux of electrons and positrons. Supernovae are astrophysical objects with the potential to explain these observations. In this work, we present an updated study of the astrophysical sources of lepton cosmic rays and the possible and the possible explanation of the anomalies in terms of astrophysical sources.

Lineros, Roberto A

2010-01-01

378

The Emerging Picture of Supernova Remnants and GRBs at High Energies  

Science.gov (United States)

In the last two years, high-energy studies of supernova remnants (SNRs) and gamma-ray bursts (GRBs) have yielded many new insights regarding the nature of explosions and their environments. In this talk, I will highlight several recent advances in these fields catalyzed by high energy theory and observations, with emphasis on progenitor systems, nucleosynthesis, and particle acceleration. Finally, I will discuss anticipated advances with upcoming facilities, like Astro-H and Advanced LIGO.

Lopez, Laura A.

2014-08-01

379

Soft X-ray emission in Eridanus: An old supernova remnant  

International Nuclear Information System (INIS)

Data are presented on the soft X-ray intensity and spectrum of a region of extended emission in the constellation Eridanus. This region also includes optical filaments, the hard X-ray source 3U 0431--10, the radio pulsar MP 0450, a neutral hydrogen shell structure, and an O VI absorption feature. It is suggested that these features are all part of an old supernova remnant with an age in the range 105--106 yrs

380

Constraining the Evolutionary Fate of Central Compact Objects: "Old" Radio Pulsars in Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Central compact objects (CCOs) constitute a population of radio-quiet, slowly-spinning ($\\ge$100 ms) young neutron stars with anomalously high thermal X-ray luminosities. Their spin-down properties imply weak dipole magnetic fields ($\\sim$$10^{10-11}$ G) and characteristic ages much greater than the ages of their host supernova remnants (SNRs). However, CCOs may possess strong "hidden" internal magnetic fields that may re-emerge on timescales $\\gtrsim$10 kyr, with the neutro...

Bogdanov, Slavko; Ng, C. -y; Kaspi, Victoria M.

2014-01-01

 
 
 
 
381

MODIFIED EQUIPARTITION CALCULATION FOR SUPERNOVA REMNANTS. CASES ? = 0.5 AND ? = 1  

International Nuclear Information System (INIS)

The equipartition or minimum energy calculation is a well-known procedure for estimating the magnetic field strength and the total energy in the magnetic field and cosmic ray particles by using only the radio synchrotron emission. In one of our previous papers, we have offered a modified equipartition calculation for supernova remnants (SNRs) with spectral indices 0.5 < ? < 1. Here we extend the analysis to SNRs with ? = 0.5 and ? = 1

382

Non-thermal emission from young supernova remnants: Implications on cosmic ray acceleration  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For a long time, supernova remnants have been thought to constitute the main source of galactic cosmic rays. Plausible mechanisms have been proposed through which these objects would be able to transfer some of their energy to charged particles. Detailed studies of SNRs, particularly allowed by the spectral and spatial resolution obtained with telescopes such as the Chandra X-Ray Observatory, have permitted us to understand some of the properties of high-energy particles within these objects...

Araya-arguedas, Miguel A.

2011-01-01

383

Discovery of molecular shells associated with supernova remnants. (II) Kesteven 75  

CERN Document Server

The young composite supernova remnant (SNR) Kesteven 75, with a pulsar wind nebula at its center, has an unusual morphology with a bright southern half-shell structure in multiwavelengths. The distance to Kes 75 has long been uncertain. Aiming to address these issues, we have made millimeter spectroscopic observations of the molecular gas toward the remnant. The V_{LSR}~83--96 km/s molecular clouds (MCs) are found to overlap a large north-western region of the remnant and are suggested to be located in front of the SNR along the line of sight. Also in the remnant area, the V_{LSR}= 45--58 km/s MC shows a blue-shifted broadening in the 12CO (J=1-0) line profile and a perturbed position-velocity structure near the edge of the remnant, with the intensity centroid sitting in the northern area of the remnant. In particular, a cavity surrounded by a molecular shell is unveiled in the intensity map in the broadened blue wing (45--51 km/s), and the southern molecular shell follows the bright partial SNR shell seen in...

Su, Yang; Yang, Ji; Koo, Bon-Chul; Zhou, Xin; Jeong, Il-Gyo; Zhang, Chun-Guang

2008-01-01

384

High-Resolution X-Ray Imaging of Supernova Remnant 1987A  

Science.gov (United States)

We report observations of the remnant of supernova 1987A with the High Resolution Camera (HRC) on board the Chandra X-ray Observatory. A direct image from the HRC resolves the annular structure of the X-ray remnant, confirming the morphology previously inferred by deconvolution of lower resolution data from the Advanced CCD Imaging Spectrometer. Detailed spatial modeling shows that a thin ring plus a thin shell gives statistically the best description of the overall remnant structure, and suggests an outer radius of 0farcs96 ± 0farcs05 ± 0farcs03 for the X-ray-emitting region, with the two uncertainties corresponding to the statistical and systematic errors, respectively. This is very similar to the radius determined by a similar modeling technique for the radio shell at a comparable epoch, in contrast to previous claims that the remnant is 10%-15% smaller at X-rays than in the radio band. The HRC observations put a flux limit of 0.010 counts s-1 (99% confidence level, 0.08-10 keV range) on any compact source at the remnant center. Assuming the same foreground neutral hydrogen column density as toward the remnant, this allows us to rule out an unobscured neutron star with surface temperature T ? > 2.5 MK observed at infinity, a bright pulsar wind nebula or a magnetar.

Ng, C.-Y.; Gaensler, B. M.; Murray, S. S.; Slane, P. O.; Park, S.; Staveley-Smith, L.; Manchester, R. N.; Burrows, D. N.

2009-11-01

385

HIGH-RESOLUTION X-RAY IMAGING OF SUPERNOVA REMNANT 1987A  

International Nuclear Information System (INIS)

We report observations of the remnant of supernova 1987A with the High Resolution Camera (HRC) on board the Chandra X-ray Observatory. A direct image from the HRC resolves the annular structure of the X-ray remnant, confirming the morphology previously inferred by deconvolution of lower resolution data from the Advanced CCD Imaging Spectrometer. Detailed spatial modeling shows that a thin ring plus a thin shell gives statistically the best description of the overall remnant structure, and suggests an outer radius of 0.''96 ± 0.''05 ± 0.''03 for the X-ray-emitting region, with the two uncertainties corresponding to the statistical and systematic errors, respectively. This is very similar to the radius determined by a similar modeling technique for the radio shell at a comparable epoch, in contrast to previous claims that the remnant is 10%-15% smaller at X-rays than in the radio band. The HRC observations put a flux limit of 0.010 counts s-1 (99% confidence level, 0.08-10 keV range) on any compact source at the remnant center. Assuming the same foreground neutral hydrogen column density as toward the remnant, this allows us to rule out an unobscured neutron star with surface temperature T ? > 2.5 MK observed at infinity, a bright pulsar wind nebula or a magnetar.

386

A CHANDRA OBSERVATION OF SUPERNOVA REMNANT G350.1-0.3 AND ITS CENTRAL COMPACT OBJECT  

International Nuclear Information System (INIS)

We present a new Chandra observation of supernova remnant (SNR) G350.1-0.3. The high-resolution X-ray data reveal previously unresolved filamentary structures and allow us to perform detailed spectroscopy in the diffuse regions of this SNR. Spectral analysis demonstrates that the region of brightest emission is dominated by hot, metal-rich ejecta while the ambient material along the perimeter of the ejecta region and throughout the remnant's western half is mostly low-temperature, shocked interstellar/circumstellar medium with solar-type composition. The data reveal that the emission extends far to the west of the ejecta region and imply a lower limit of 6.6 pc on the diameter of the source (at a distance of 4.5 kpc). We show that G350.1-0.3 is likely in the free expansion (ejecta-dominated) stage and calculate an age of 600-1200 years. The derived relationship between the shock velocity and the electron/proton temperature ratio is found to be entirely consistent with that of other SNRs. We perform spectral fits on the X-ray source XMMU J172054.5-372652, a candidate central compact object (CCO), and find that its spectral properties fall within the typical range of other CCOs. We also present archival 24 ?m data of G350.1-0.3 taken with the Spitzer Space Telescope during the MIPSGAL galactic survey and find that the infrared and X-ray morphologies are well correlated. These results help to explain this remnant's peculiar asymmetries and shed new light on its dynamics and evolution.

387

CO J=2-1 Observations toward the Supernova Remnant G54.1+0.3  

CERN Document Server

We present 12CO J = 2-1 line observations of G54.1+0.3, a composite supernova remnant with a mid-infrared (MIR) loop surrounding the central pulsar wind nebula (PWN). We mapped an area of 12' x 9' around the PWN and its associated MIR loop. We confirm two velocity components that had been proposed to be possibly interacting with the PWN/MIR-loop; the +53 km/s cloud that appears in contact with the eastern boundary of the PWN and the +23 km/s cloud that has CO emission coincident with the MIR loop. We have not found a direct evidence for the interaction in either of these clouds. Instead, we detected an 5'-long arc-like cloud at +15-+23 km/s with a systematic velocity gradient of ~3 km/s/arcmin and broad-line emitting CO gas having widths (FWHM) of <7 km/s in the western interior of the supernova remnant. We discuss their association with the supernova remnant.

Lee, Jung-Won; Lee, Jeong-Eun

2012-01-01

388

GSH 138-01-94: An Old Supernova Remnant in the Far Outer Galaxy  

Science.gov (United States)

The properties of the Galactic H I shell GSH 138-01-94 are derived from data of the Canadian Galactic Plane Survey. The basic parameters of GSH 138-01-94 were determined by fitting the expansion of a thin shell to the expansion velocity field on the sky. The kinematic distance is 16.6 kpc for vLSR=-94.2+/-0.5kms-1. The radius is 180+/-10pc, the expansion velocity vexp=11.8+/-0.9kms-1, and the mass 2×105Msolar. No radio-continuum counterpart of the shell was detected at 21 cm or at 74 cm. Absorption of a background continuum source constrains the spin temperature of H I in the shell to Ts=230367173K. The expansion age of GSH 138-01-94 is 4.3 Myr. These observables are in excellent agreement with predictions from hydrodynamic models for a supernova remnant in a low-density, low-metallicity environment such as the outer Galaxy. GSH 138-01-94 is then the largest and the oldest supernova remnant known. It provides direct evidence for the release of mechanical energy in the interstellar medium by stars in the outer Galaxy. We argue that such old supernova remnants are to be found in low-density, low-metallicity environments such as the outer Galaxy, dwarf galaxies, and low surface brightness galaxies.

Stil, J. M.; Irwin, J. A.

2001-12-01

389

Discriminating the Progenitor Type of Supernova Remnants with Iron K-Shell Emission  

CERN Document Server

Supernova remnants (SNRs) retain crucial information about both their parent explosion and circumstellar material left behind by their progenitor. However, the complexity of the interaction between supernova ejecta and ambient medium often blurs this information, and it is not uncommon for the basic progenitor type (Ia or core-collapse) of well-studied remnants to remain uncertain. Here we present a powerful new observational diagnostic to discriminate between progenitor types and constrain the ambient medium density of SNRs solely using Fe K-shell X-ray emission. We analyze all extant Suzaku observations of SNRs and detect Fe K alpha emission from 23 young or middle-aged remnants, including five first detections (IC 443, G292.0+1.8, G337.2-0.7, N49, and N63A). The Fe K alpha centroids clearly separate progenitor types, with the Fe-rich ejecta in Type Ia remnants being significantly less ionized than in core-collapse SNRs. Within each progenitor group, the Fe K alpha luminosity and centroid are well correlate...

Yamaguchi, Hiroya; Petre, Robert; Nakano, Toshio; Castro, Daniel; Enoto, Teruaki; Hiraga, Junko S; Hughes, John P; Maeda, Yoshitomo; Nobukawa, Masayoshi; Safi-Harb, Samar; Slane, Patrick O; Smith, Randall K; Uchida, Hiroyuki

2014-01-01

390

The radio remnant of Supernova 1987A at high frequencies and high resolution  

CERN Document Server

As the remnant of Supernova (SN) 1987A has been getting brighter over time, new observations at high frequencies have allowed imaging of the radio emission at unprecedented detail. We present a new radio image at 44 GHz of the supernova remnant (SNR), derived from observations performed with the Australia Telescope Compact Array (ATCA) in 2011. The diffraction-limited image has a resolution of $349\\times225$ mas, which is the highest achieved to date in high-dynamic range images of the SNR. We also present a new image at 18 GHz, also derived from ATCA observations performed in 2011, which is super-resolved to $0./!/!^{\\prime\\prime}25$. The new 44 and 18 GHz images yield the first high-resolution spectral index map of the remnant. The comparison of the 44 GHz image with contemporaneous X-ray and H$\\alpha$ observations allows further investigations of the nature of the remnant asymmetry and sheds more light into the progenitor hypotheses and SN explosion. In light of simple free-free absorption models, we discu...

Zanardo, G; Ng, C -Y; Gaensler, B M; Potter, T M; Manchester, R N; Tzioumis, A K

2013-01-01

391

Far-ultraviolet Cooling Features Of A Mixed-Morphology Supernova Remnant  

Science.gov (United States)

Mixed-Morphology Supernova Remnants (MM SNRs) are well known for their unusual center-filled X-ray morphology. Two models have been explained such property, employing different distributions of cold-and-dense gas components around the supernova. To investigate the cooling feature of MM SNRs, we observed the Antlia SNR, a large MM SNR ( 24° in diameter), in far-ultraviolet domain with Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR, aka FIMS). We detected C III ?977 and C IV ??1548,1551 emission lines, which might be generated as the hot gas of the remnant cool down interacting with the ambient cold gas. The C IV emission line map shows a clumpy distribution, and the temperature profile---inferred from the line ratio of C III and C IV---is increasing near the edge of the remnant. These results are more compatible with the thermal evaporation model than the thermal conduction model, which predicts the edge-concentrated C IV feature and the decreasing temperature profile near the edge of the remnant.

Shinn, Jong-Ho; Min, K.; Sankrit, R.; Ryu, K.; Kim, I.; Han, W.; Nam, U.; Park, J.; Edelstein, J.; Korpela, E.; FIMS Team at KAIST; FIMS Team at KASI; SPEAR Team at SSL

2007-05-01

392

Massive Star Formation Near the Supernova Remnant W30  

Directory of Open Access Journals (Sweden)

Full Text Available Presentamos observaciones del radiocontinuo a 6 cm (con una resolución de 1 segundo de arco de sitios candidatos a ser regiones de formación estelar, los cuales se encuentran situados alrededor del remanente de supernova W30. Se detectó un total de nueve fuentes, algunas de las cuales pueden ser regiones H II ultracompactas. Una de estas fuentes, la G8.139-0:026, tiene una forma cometaria. De las ocho fuentes IRAS observadas, sólo tres tienen fuentes en radio continuo cercanas (< 1``. La baja tasa de detección de contrapartes en radio de las fuentes IRAS sugiere que W30 es un remanente joven que puede haber iniciado el proceso de formación estelar (lo cual es indicado por la presencia de fuentes en infrarrojo, pero este proceso de formación aún no ha concluido (lo cual parece estar de acuerdo con la falta relativa de contrapartes en el radiocontinuo.

P. Ojeda May

2002-01-01

393

Molecular clouds and supernova remnants in the outer galaxy  

International Nuclear Information System (INIS)

The study of extragalactic supernova (SNs) suggests that Type II SNs, not Type I, tend to occur near extreme optical Population I objects, but the detection of these objects in the Galaxy is limited by heavy local obscuration. A CO survey has been conducted toward every confirmed outer Galaxy SNR from l = 70 to 210 deg, for a total of 26, and it is found that roughly half of them, within uncertainties of distance estimates, revealed spatial coincidences with large molecular cloud complexes. Most of the cloud complexes in these coincidences probably are the birthplaces of the progenitors of the corresponding Type II SNRs, because it is statistically improbable that the coincidences result from change superposition. 118 references

394

Role of ejecta clumping and back-reaction of accelerated cosmic rays in the evolution of Type Ia supernova remnants  

CERN Document Server

We investigate the role played by initial clumping of ejecta and by efficient acceleration of cosmic rays (CRs) in determining the density structure of the post-shock region of a Type Ia supernova remnant (SNR) through detailed 3D MHD modeling. Our model describes the expansion of a SNR through a magnetized interstellar medium (ISM), including the initial clumping of ejecta and the effects on shock dynamics due to back-reaction of accelerated CRs. The model predictions are compared to the observations of SN 1006. We found that the back-reaction of accelerated CRs alone cannot reproduce the observed separation between the forward shock (FS) and the contact discontinuity (CD) unless the energy losses through CR acceleration and escape are very large and independent of the obliquity angle. On the contrary, the clumping of ejecta can naturally reproduce the observed small separation and the occurrence of protrusions observed in SN 1006, even without the need of accelerated CRs. We conclude that FS-CD separation i...

Orlando, S; Miceli, M; Petruk, O; Pumo, M L

2012-01-01

395

Production of high energy neutrinos in relativistic supernova shock waves  

International Nuclear Information System (INIS)

The possibility of producing high-energy neutrinos (> approx. 10 GeV) in relativistic supernova shock waves is considered. It is shown that, even if the dissipation in such shocks is due to hard hadron--hadron collisions, the resulting flux of neutrinos is too small to be observed by currently envisioned detectors. The associated burst of hard ?-rays, however, may be detectable. 3 tables

396

SNR 0104-72.3: A REMNANT OF A TYPE Ia SUPERNOVA IN A STAR-FORMING REGION?  

International Nuclear Information System (INIS)

We report our 110 ks Chandra observations of the supernova remnant (SNR) 0104-72.3 in the Small Magellanic Cloud (SMC). The X-ray morphology shows two prominent lobes along the northwest-southeast direction and a soft faint arc in the east. Previous low-resolution X-ray images attributed the unresolved emission from the southeastern lobe to a Be/X-ray star. Our high-resolution Chandra data clearly show that this emission is diffuse, shock-heated plasma, with negligible X-ray emission from the Be star. The eastern arc is positionally coincident with a filament seen in optical and infrared observations. Its X-ray spectrum is well fit by plasma of normal SMC abundances, suggesting that it is from shocked ambient gas. The X-ray spectra of the lobes show overabundant Fe, which is interpreted as emission from the reverse-shocked Fe-rich ejecta. The overall spectral characteristics of the lobes and the arc are similar to those of Type Ia SNRs, and we propose that SNR 0104-72.3 is the first case for a robust candidate Type Ia SNR in the SMC. On the other hand, the remnant appears to be interacting with dense clouds toward the east and to be associated with a nearby star-forming region. These features are unusual for a standard Type Ia SNR. Our results suggest an intriguing possibility that the progenitor of SNR 0104-72.3 might have been a white dwarf of a relatively young population.

397

To what type of supernovae do old galactic remnants belong; the evolution of envelopes in the interstellar medium  

International Nuclear Information System (INIS)

Investigation of the evolution of supernova remnants in the Galaxy medium is carried out. The investigation of the kinematics of old optical Supernova remnants allows to estimate the mean initial energy of the envelopes, E0=(3.7+-1.5)x1050 erg; this gives the mass ejected approximately equal to 0.3 Msub(Sun) for the type 1 (V0=104 km/s), and 1-2 Msub(Sun) for the type 2. Supernovae (V0=(5-7)x103 km/s.) For determining the Supernova type, the physical association of the remnants with gas-and-dust complexes and OB-associations is considered. It is shown that the optical remnants IC443, the Monoceros Loop, the weak envelope of W1, W28, Vela X, and possibly HB3, may have been formed in the type 2 Supernovae explosion; the late stage of the evolution was accompanied by an intense mass loss. The problem of the ''plerions'' evolution is considered. It is suggested that as far as their central sources damp, they turn into classical envelope radio Supernova remnants

398

Fermi-LAT Observation of Supernova Remnant S147  

Energy Technology Data Exchange (ETDEWEB)

We present an analysis of gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region around SNR S147 (G180.0-1.7). A spatially extended gamma-ray source detected in an energy range of 0.2-10 GeV is found to coincide with SNR S147. We confirm its spatial extension at >5{sigma} confidence level. The gamma-ray flux is (3.8 {+-} 0.6) x 10{sup -8} photons cm{sup -2} s{sup -1}, corresponding to a luminosity of 1.3 x 10{sup 34} (d/1.3 kpc){sup 2} erg s{sup -1} in this energy range. The gamma-ray emission exhibits a possible spatial correlation with prominent H{alpha} filaments of S147. There is no indication that the gamma-ray emission comes from the associated pulsar PSR J0538+2817. The gamma-ray spectrum integrated over the remnant is likely dominated by the decay of neutral {pi} mesons produced through the proton-proton collisions in the filaments. Reacceleration of pre-existing CRs and subsequent adiabatic compression in the filaments is sufficient to provide the required energy density of high-energy protons.

Katsuta, J.; Uchiyama, Y.; Tanaka, T.; /SLAC /KIPAC, Menlo Park; Tajima, H.; /SLAC /KIPAC, Menlo Park /Nagoya U., Solar-Terrestrial Environ. Lab.; Bechtol, K.; Funk, S.; Lande, J.; /SLAC /KIPAC, Menlo Park; Ballet, J.; /AIM, Saclay; Hanabata, Y.; /Hiroshima U.; Lemoine-Goumard, M.; /CENBG, Gradignan; Takahashi, T.; /JAXA, Sagamihara

2012-08-17

399