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1

Shock waves in supernova remnants  

International Nuclear Information System (INIS)

Several problems relating to the structure of supernova remnants are discussed. The optical component is considered in some detail, including the evolution of the abundance-dependent line ratio I(Hsub(?))/I(NII). X-ray and radio observations are also considered. The structure of shock waves in an unmagnetised plasma is discussed. The collisional case is solved by assuming quasi-neutrality and neglecting heat transfer between electrons and ions. A collisionless model is presented in which the main dissipative processes are the beam and the drift instabilities. It is suggested that the shock waves occuring in young supernova remnants are mixed structures. At the leading edge of the shock classical electron viscosity rapidly dissipates the initial electron kinetic energy. This is followed by the collisionless processes, which will dissipate most of the plasma kinetic energy. Electron heating is not properly taken into account in this model, and only the rapid deceleration of this component can be reproduced. This occurs over a distance that is so short that the ion response is insignificant. (author)

2

Shocked Clouds in the Vela Supernova Remnant  

Science.gov (United States)

Unusually strong high-excitation C I has been detected in eleven lines of sight through the Vela supernova remnant by means of UV absorption-line studies of IUE data. Most of these lines of sight lie near the western edge of the X-ray bright region of the supernova remnant in a spatially distinct band approximately 1deg by 4deg oriented approximately north/south. The high-excitation C I (denoted C I*) is interpreted as evidence of a complex of shocked dense clouds inside the supernova remnant, due to the high pressures indicated in this region. To further analyze the properties of this region of C I*, we present new HIRES-processed IRAS data of the entire Vela SNR. A temperature map calculated from the HIRES IRAS data, based on a two-component dust model, reveals the signature of hot dust at several locations in the SNR. The hot dust is anti-correlated spatially with X-ray emission as revealed by ROSAT, as would be expected for a dusty medium interacting with a shock wave. The regions of hot dust are strongly correlated with optical filaments, supporting a scenario of dense clouds interior to the SNR that have been shocked and are now cooling behind the supernova blast wave. With few exceptions, the lines of sight to the strong C I* pass through regions of hot dust and optical filaments. Possible mechanisms for the production of the anomalously large columns of C I and C I* are discussed. Dense clouds on the back western hemisphere of the remnant may explain the relatively low X-ray emission in the western portion of the Vela supernova remnant due to the slower forward shock velocity in regions where the shock has encountered the dense clouds. An alternate explanation for the presence of neutral, excited state, and ionized species along the same line of sight may be a magnetic precusor that heats and compresses the gas ahead of the shock.

Nichols, Joy S.; Slavin, Jonathan D.

2004-01-01

3

Particle acceleration in supernova-remnant shocks  

CERN Document Server

It has been known for over 50 years that the radio emission from shell supernova remnants (SNRs) indicates the presence of electrons with energies in the GeV range emitting synchrotron radiation. The discovery of nonthermal X-ray emission from supernova remnants is now 30 years old, and its interpretation as the extension of the radio synchrotron spectrum requires electrons with energies of up to 100 TeV. SNRs are now detected at GeV and TeV photon energies as well. Strong suggestions of the presence of energetic ions exist, but conclusive evidence remains elusive. Several arguments suggest that magnetic fields in SNRs are amplified by orders of magnitude from their values in the ambient interstellar medium. Supernova remnants are thus an excellent laboratory in which to study processes taking place in very high Mach-number shocks. I review the observations of high-energy emission from SNRs, and the theoretical framework in which those observations are interpreted.

Reynolds, S P

2010-01-01

4

Supernova remnants and the physics of strong shock waves  

Science.gov (United States)

This paper reports on a Workshop on Supernova Remnants and the Physics of Strong Shock Waves hosted by North Carolina State University at Raleigh, North Carolina, September 16-18, 1993. The workshop brought together observers, shock theorists, cosmic-ray specialists, and simulators to address the role supernova remnants can play in furthering our understanding of the complex plasma physics associated with collisionless shocks and particle acceleration. Over fifty scientists presented papers on various aspects of supernova remnants. In lieu of a proceedings volume, we present here a synopsis of the workshop, in the form of brief summaries of each workshop session.

Ellison, Donald C.; Reynolds, Stephen P.; Borkowski, Kazimierz; Chevalier, Roger; Cox, Donald P.; Dickel, John R.; Pisarski, Ryszard; Raymond, John; Spangler, Stephen R.; Volk, Heinrich J.

1994-01-01

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 acceration in shock waves, while in other remnants a central compact object is probably responsible for particle acceleration

6

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)

7

Cosmic Ray Spectrum in Supernova Remnant Shocks  

CERN Document Server

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

Kang, Hyesung

2010-01-01

8

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

9

Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves  

CERN Document Server

Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al. (1996), we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities >~ 200 km/s for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are incre...

Slavin, Jonathan D; Jones, Anthony P

2015-01-01

10

Supernova remnant masers: Shock interactions with molecular clouds  

Science.gov (United States)

Maser emission from the 1720-MHz transition of hydroxyl(OH) has identified shock interactions in 10% of all supernova remnants(SNRs). Such maser-emitting SNRs are also bright in molecular line emission. Though somewhat rare, SNRs interacting with dense molecular clouds are an important class in which to study cosmic ray acceleration, SNR evolution, and effects on the energetics and chemistry of the interstellar medium. To study molecular shocks via a multiwavelength approach, the VLA, GBT, Spitzer Space Telescope have been used in the following ways: (i) With the GBT widespread OH(1720 MHz) emission and absorption in other OH lines is observed across the interaction site. Observations of all four ground-state transitions at 1720, 1667/5 and 1612 MHz allows us to model OH excitation, yielding the temperature, density and OH abundance in the post-shock gas. Maser emission is found to have a higher flux density with the GBT than with high-resolution VLA observations for 10 of 15 observed remnants, suggesting maser emission is present on large spatial scales. (ii) Sensitive VLA observations of select SNRs (W44, IC 443, Kes 69, 3C 391, G357.7+0.3) reveal the nature of enhanced 1720 MHz emission. Numerous weak compact masers as well as diffuse extended emission are detected tracing the shock-front. Zeeman splitting of masers permits the post-shock magnetic field strength and the line of sight field direction to be directly measured. (iii) Rotational lines of molecular hydrogen are detected at the position of several masers with Spitzer IRS spectroscopy between 5 and 35 mm. Excitation of the hydrogen lines requires the passage of a C-type shock through dense molecular gas, in agreement with the conditions derived from OH excitation. The presence of bright ionic lines requires multiple shocks present at the interaction site. (iv) A new survey for SNR-masers has identified four new interacting SNRs within 10 degrees of the Galactic Center. Maser-emitting SNRs are found to be preferentially distributed in the inner Galaxy, and preferentially associated with gamma-ray sources. To date, nine remnants with TeV or GeV-energy coincidences also harbor OH(1720 MHz) masers, making this signpost of interaction a potential signpost of cosmic-ray acceleration as well. The enhanced local cosmic ray density is a viable mechanism to produce the high columns of OH which are observed in these sources.

Hewitt, John William

11

MAGNETIC AMPLIFICATION BY MAGNETIZED COSMIC RAYS IN SUPERNOVA REMNANT SHOCKS  

International Nuclear Information System (INIS)

X-ray observations of synchrotron rims in supernova remnant (SNR) shocks show evidence of efficient electron acceleration and strong magnetic field amplification (a factor of ?100 between the upstream and downstream medium). This amplification may be due to plasma instabilities driven by shock-accelerated particles or cosmic rays (CRs), as they propagate ahead of the shocks. One candidate process is the cosmic ray current-driven (CRCD) instability caused by the electric current of 'unmagnetized' CRs (i.e., CRs whose Larmor radii are much larger than the length scale of the CRCD modes) propagating parallel to the upstream magnetic field. Particle-in-cell (PIC) simulations have shown that the back-reaction of the amplified field on CRs would limit the amplification factor of this instability to less than ?10 in galactic SNRs (not including the additional field compression at the shock). In this paper, we study the possibility of further amplification driven near shocks by 'magnetized' CRs, whose Larmor radii are smaller than the length scale of the field that was previously amplified by the CRCD instability. We find that additional amplification can occur due to a new instability, driven by the CR current perpendicular to the field, which we term the perpendicular current-driven instability (PCDI). We derive the growth rate of this instability and, using PIC simulations, study its non-linear evolution. We show that the maximum amplification of PCDI is determined by mplification of PCDI is determined by the disruption of CR current, which happens when CR Larmor radii in the amplified field become comparable to the length scale of the instability. We find that, in regions close to the shock, PCDI grows on scales smaller than the scales of the CRCD instability, and, therefore, it results in larger amplification of the field (amplification factor up to ?45). One possible observational signature of PCDI is the characteristic dependence of the amplified field on the shock velocity, B 2 ? v 2 sh, which contrasts with the one corresponding to the CRCD instability acting alone, B 2 ? v 3 sh. Our results strengthen the idea of CRs driving a significant part of the magnetic field amplification observed in SNR shocks.

12

Supernova remnants  

International Nuclear Information System (INIS)

A short review is given of the formation of supernova remnants. The main points of discussion are: the late stages in the evolution of a star, the supernova explosion, the blast wave in the envelope of the star, early stages in the expansion, the question whether there is an energy input from a central source, the interaction with the interstellar medium in phase I (the majority of the mass of the remnant comes from the star) and phase II (the majority is interstellar gas), the onset of cooling, the formation of filaments and the final stage. (BJ)

13

On cosmic-ray production efficiency at supernova remnant shocks propagating into realistic diffuse interstellar medium  

CERN Document Server

Using three-dimensional magnetohydrodynamics simulations, we show that the efficiency of cosmic-ray (CR) production at supernova remnants (SNRs) is over-predicted if it is estimated based on proper motion measurements of H$\\alpha$ filaments in combination with shock-jump conditions. Density fluctuations of upstream medium make shock waves rippled and oblique almost everywhere. The kinetic energy of the shock wave is transfered into that of downstream turbulence as well as thermal energy which is related to the shock velocity component normal to the shock surface. In our case, the apparent efficiency goes up as high as $10\\sim40\\ \\%$ in spite of no CR acceleration.

Shimoda, Jiro; Ohira, Yutaka; Yamazaki, Ryo; Bamba, Aya; Vink, Jacco

2014-01-01

14

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

15

An Integral View of Balmer-dominated Shocks in Supernova Remnants  

Science.gov (United States)

We present integral-field spectroscopic observations with the VIMOS-IFU at the VLT of fast (2000-3000 kms-1) 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? lines across a large part of the remnant.

Nikoli?, Sladjana; van de Ven, Glenn; Heng, Kevin; Kupko, Daniel; Lopez Aguerri, Jose Alfonso; Méndez-Abreu, Jairo; Serra, Joan Font; Beckman, John

2014-01-01

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

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

CERN Document Server

Many fast supernova remnant shocks show spectra dominated by Balmer lines. The H$\\alpha$ profiles have a narrow component explained by direct excitations and a thermally Doppler broadened component due to atoms that undergo charge exchange in the post-shock region. However, the standard model does not take into account the cosmic-ray shock precursor, which compresses and accelerates plasma ahead of the shock. In strong precursors with sufficiently high densities, the processes of charge exchange, excitation and ionization will affect the widths of both narrow and broad line components. Moreover, the difference in velocity between the neutrals and the precursor plasma gives rise to frictional heating due to charge exchange and ionization in the precursor. In extreme cases, all neutrals can be ionized by the precursor. In this paper we compute the ion and electron heating for a wide range of shock parameters, along with the velocity distribution of the neutrals that reach the shock. Our calculations predict ver...

Raymond, John C; Helder, E A; de Laat, A

2011-01-01

18

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

19

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

CERN Document Server

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

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

1997-01-01

20

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

International Nuclear Information System (INIS)

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

 
 
 
 
21

Plasma instabilities as a result of charge exchange in the downstream region of supernova remnant shocks  

CERN Document Server

H-alpha 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 micro 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.

Ohira, Yutaka; Takahara, Fumio

2009-01-01

22

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

CERN Document Server

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

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

2008-01-01

23

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

International Nuclear Information System (INIS)

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

24

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

International Nuclear Information System (INIS)

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

25

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

26

Supernova Remnant SNR 0509 lithograph  

Science.gov (United States)

This Hubble Space Telescope image shows what appears to be a delicate bubble of gas floating serenely in space. In actuality, the bubble is the visible remnant of a powerful supernova explosion called SNR 0509. The bubble was formed from gas being swept up by the expanding shock wave. In the accompanying educational activity, In Search of ... Supernova Remnants, students investigate supernova explosions and remnants through a level 1 inquiry activity using the images and text from the lithograph and other resources. A level 1 inquiry activity can help prepare students to become independent thinkers.

27

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

28

The Honeycomb supernova remnant  

Science.gov (United States)

At 2.5 min southeast of SN 1987A, the Honeycomb Nebula Supernova remnant (SNR) is named after its interesting morphology, which consists of over ten loops with sizes of 2-3 pc. High-dispersion spectra of these loops show hemispheres expanding toward the observer at 100-300 km/s. Using archival data X-ray data and a combination of new and archival radio data, we find bright X-ray and nonthermal radio emisssion associated with the Honeycomb Nebula. New CCD images further show enhanced (S II) H-alpha ratios. These results confirm a model in which the Honeycomb Nebula is due to a supernova shock front, traveling toward the observer, encountering an intervening sheet of dense, but porous, interstellar gas. The bulk of the supernova remnant resides in a low-density cavity, and is not otherwise visible. The situation is similar to the hidden supernova remnants postulated for the X-ray bright superbubbles. The Honeycomb Nebula has an unusually steep radio spectral index (S(sub nu) is proportional to nu(exp -1.2)), normally associated with young SNRs.

Chu, You-Hua; Dickel, John R.; Staveley-Smith, Lister; Osterberg, Juergen; Smith, R. Chris

1995-01-01

29

OH Masers and Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OH(1720 MHz) masers are created by the interaction of supernova remnants with molecular clouds. These masers are pumped by collisions in warm, shocked molecular gas with OH column densities in the range 10^{16}--10^{17} cm^{-2}. Excitation calculations suggest that inversion of the 6049 MHz OH line may occur at the higher column densities that have been inferred from main-line absorption studies of supernova remnants with the Green Bank Telescope. OH(6049 MHz) masers have th...

Wardle, Mark; Mcdonnell, Korinne

2012-01-01

30

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

CERN Document Server

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

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

2014-01-01

31

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

32

Time-Dependent Diffusive Shock Acceleration in Slow Supernova Remnant Shocks  

Science.gov (United States)

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 ?^0-decay emission.We allow for a power law momentum dependence of the diffusion coefficient, finding that a power law index of 0.5 is favored.

Xiaping, Tang; Chevalier, Roger

2015-01-01

33

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

34

Thermal and Nonthermal X-ray Emission from the Forward Shock in Tycho's Supernova Remnant  

Science.gov (United States)

We present Chandra CCD images of Tycho's supernova remnant that delineate its outer shock, seen as a thin, smooth rim along the straight northeastern edge and most of the circular western half. The images also show that the Si and S ejecta are highly clumpy, and have reached the forward shock at numerous locations. Most of the X-ray spectra that we examine along the rim show line emission from Si and S, which in some cases must come from ejecta; the continuum is well represented by either thermal or nonthermal models. In the case that the continuum is assumed to be thermal, the temperatures at the rim are all similar at about 2 keV, and the ionization ages are very low because of the overall weakness of the line emission. Assuming shock velocities inferred from radio and X-ray expansion measurements, these temperatures are substantially below those expected for equilibration of the electron and ion temperatures; electron to mean temperature ratios of approximately less than 0.1 - 0.2 indicate at most modest collisionless heating of the electrons at the shock. The nonthermal contribution to these spectra may be important, however, and may account for as many as half of the counts in the 4-6 keV energy range, based on an extrapolation of the hard X-ray spectrum above 10 keV.

Hwang, Una; Decourchelle, Anne; Holt, Stephen S.; Petre, Robert; White, Nicholas E. (Technical Monitor)

2002-01-01

35

Catastrophic cooling in supernova remnants  

International Nuclear Information System (INIS)

The transition from the adiabatic (Sedov) phase of a spherically symmetric supernova remnant is studied numerically. The input physics is kept as simple as possible, but the interstellar magnetic field is included. It is shown that, for sufficiently large values of the explosion energy and ambient density, multiple shocks are formed. These shocks continue to be formed until the expansion velocity of the remnant falls below 108 km s-1. The X-ray luminosity of the remnant is also calculated and it is found that the mean X-ray temperature does not correlate with the expansion velocity once radiative cooling becomes important. (author)

36

Broad Balmer line emission and cosmic ray acceleration efficiency in supernova remnant shocks  

CERN Document Server

Balmer emission may be a powerful diagnostic tool to test the paradigm of cosmic ray (CR) acceleration in young supernova remnant (SNR) shocks. The width of the broad Balmer line is a direct indicator of the downstream plasma temperature. In case of efficient particle acceleration an appreciable fraction of the total kinetic energy of the plasma is channeled into CRs, therefore the downstream temperature decreases and so does the broad Balmer line width. This width also depends on the level of thermal equilibration between ions and neutral hydrogen atoms in the downstream. Since in general in young SNR shocks only a few charge exchange (CE) reactions occur before ionization, equilibration between ions and neutrals is not reached, and a kinetic description of the neutrals is required in order to properly compute Balmer emission. We provide a method for the calculation of Balmer emission using a self-consistent description of the shock structure in the presence of neutrals and CRs. We use a recently developed s...

Morlino, G; Bandiera, R; Amato, E

2013-01-01

37

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

CERN Document Server

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

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

2003-01-01

38

Supernova remnants and the ISM  

International Nuclear Information System (INIS)

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

39

GALACTIC AND EXTRAGALACTIC SUPERNOVA REMNANTS AS SITES OF PARTICLE ACCELERATION  

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

Manami Sasaki

2013-12-01

40

Morphology of supernova remnants  

International Nuclear Information System (INIS)

The difference in morphology between filled and shell type supernova remnants is attributed to differences in the activity of the neutron stars left by the supernovae. Pulsar activity leads to centrally concentrated remnants similar to the Crab. Non-activity as a pulsar results in all of the rotational energy loss going into dipole radiation. The pressure of this radiation creates shell-like objects with hollow interiors such as Cas A

 
 
 
 
41

Cosmic Rays From Supernova Remnants: a Brief Description of the Shock Acceleration of gas and Dust  

Science.gov (United States)

We summarize our model of galactic cosmic-ray (GCR) origin and acceleration, wherein a mixture of interstellar and/or circumstellar gas and dust is accelerated by a supernova remnant (SNR) blast wave. A detailed analysis of observed GCR abundances (Meyer et al., 1997), combined with the knowledge that many refractory elements known to be locked in grains in the interstellar medium (ISM) are abundant in cosmic rays, has lead us to revive an old suggestion (Epstein, 1980) that charged dust grains can be shock accelerated. Here, we outline results (presented more completely in Ellison et al., 1997) from a nonlinear shock model which includes (i) the direct acceleration of interstellar gas-phase ions, (ii) a simplified model for the direct acceleration of weakly charged grains to ˜100 keV amu-1 energies, simultaneously with the acceleration of the gas ions, (iii) the energy losses of grains colliding with the ambient gas, (iv) the sputtering of grains, and (v) the simultaneous acceleration of the sputtered ions to TeV energies. We show that the model produces GCR source abundance enhancements of the volatile, gas-phase elements, which are an increasing function of mass, as well as a net, mass independent, enhancement of the refractory, grain elements over protons, consistent with cosmic-ray observations. The GCR 22Ne and C excesses may also be accounted for in terms of the acceleration of 22Ne-C- enriched pre-SN Wolf-Rayet star wind material surrounding the most massive supernovae. The O excess seen in cosmic rays probably cannot be interpreted in terms of W-R star nucleosynthesis, but is easily accounted for in our model since 15 to 20% of O is trapped in grain cores and this O will be preferentially accelerated. We have expanded the parameter range explored in Ellison et al. (1997) to lower shock speeds and higher maximum cosmic-ray energies and find similar fits to the H/He ratio and the cosmic-ray source spectra.

Ellison, Donald C.; Drury, Luke O'c.; Meyer, Jean-Paul

1998-07-01

42

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

43

Maximum Energies of Shock-Accelerated Electrons in Young Shell Supernova Remnants  

Science.gov (United States)

Young supernova remnants (SNRs) are often assumed to be the source of cosmic rays up to energies approaching the slight steepening in the cosmic ray spectrum at around 1000 TeV, known as the "knee." We show that the observed X-ray emission of 14 radio-bright shell remnants, including all five historical shells, can be used to put limits on E(sub max), the energy at which the electron energy distribution must steepen from its slope at radio-emitting energies. Most of the remnants show thermal spectra, so any synchrotron component must fall below the observed X-ray fluxes. We obtain upper limits on E(sub max) by considering the most rapid physically plausible cutoff in the relativistic electron distribution, an exponential, which is as sharp or sharper than found in any more elaborate models. This maximally curved model then gives us the highest possible E(sub max) consistent with not exceeding observed X-rays. Our results are thus independent of particular models for the electron spectrum in SNRs. Assuming homogeneous emitting volumes with a constant magnetic field strength of 10 uG, no object could reach 1000 TeV, and only one, Kes 73, has an upper limit on E(sub max), above 100 TeV. All the other remnants have limits at or below 80 TeV. E(sub max) is probably set by the finite remnant lifetime rather than by synchrotron losses for remnants younger than a few thousand years, so that an observed electron steepening should be accompanied by steepening at the same energy for protons. More complicated, inhomogeneous models could allow higher values of E(sub max) in parts of the remnant, but the emission-weighted average value, that characteristic of typical electrons, should obey these limits. The young remnants are not expected to improve much over their remaining lives at producing the highest energy Galactic cosmic rays; if they cannot, this picture of cosmic-ray origin may need major alteration.

Reynolds, Stephen P.; Keohane, Jonathan W.; White, Nicholas E. (Technical Monitor)

1999-01-01

44

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.

45

Global O VI line emission from the Cygnus Loop supernova remnant and direct kinematic measurement of the associated shock  

Science.gov (United States)

A far-ultraviolet spectrophotometric emission-line mapping of the Cygnus Loop supernova remnant is presented. These are results from the first flight of the rocket-borne, High Resolution Emission Line Spectrometer. The spatial distribution of the emission is that of a limb-brightened shell, and similar to soft X-ray maps. The emission-line profiles, which are broader than the instrument resolution, were consistent with uniformly expanding shell models. Best-fit values give a radial expansion velocity to the emissive region of 185(+/-19) km/s and a reddening-corrected average surface brightness of 8.8(+/-3.6) x 10 exp -6 ergs/sq cm s sr in the doublet. Comparison of the observed brightness with predictions of both radiative and nonradiative shock models provides constraints for the global blast wave ram pressure as well as a "covering factor" of the intermediate velocity shock.

Rasmussen, Andrew; Martin, Christopher

1992-01-01

46

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)

47

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

CERN Document Server

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

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

2013-01-01

48

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

Science.gov (United States)

Although collisionless shocks are ubiquitous in astrophysics, certain key aspects of them are not well understood. In particular, the process known as collisionless electron heating, whereby electrons are rapidly energized at the shock front, is one of the main open issues in shock physics. Here, we present the first clear evidence for efficient collisionless electron heating at the reverse shock of Tycho's supernova remnant (SNR), revealed by Fe K diagnostics using high-quality X-ray data obtained by the Suzaku satellite. We detect K beta (3p yields 1s) fluorescence emission from low-ionization Fe ejecta excited by energetic thermal electrons at the reverse shock front, which peaks at a smaller radius than Fe K alpha (2p yields 1s) emission dominated by a relatively highly ionized component. Comparisons with our hydrodynamical simulations imply instantaneous electron heating to a temperature 1000 times higher than expected from Coulomb collisions alone. The unique environment of the reverse shock, which is propagating with a high Mach number into rarefied ejecta with a low magnetic field strength, puts strong constraints on the physical mechanism responsible for this heating and favors a cross-shock potential created by charge deflection at the shock front. Our sensitive observation also reveals that the reverse shock radius of this SNR is about 10% smaller than the previous measurement using the Fe K alpha morphology from the Chandra observations. Since strong Fe K beta fluorescence is expected only from low-ionization plasma where Fe ions still have many 3p electrons, this feature is key to diagnosing the plasma state and distribution of the immediate postshock ejecta in a young SNR.

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

2013-01-01

49

Particle acceleration in supernova remnants  

Science.gov (United States)

Supernova remnants (SNR) are the most likely source of galactic cosmic rays (CRs) up to the 'knee' in the spectrum at a few PeV. The theory of diffusive shock acceleration nicely supplies a power law energy distribution with approximately the desired spectral index and with suitably high efficiency. For a SNR blast wave expanding into a typical interstellar magnetic field the predicted maximum CR energy falls short of 1 PeV, but a non-resonant plasma instability allows the CRs themselves to amplify the magnetic field by orders of magnitude to a level capable of accelerating CRs to the knee.

Bell, A. R.

2009-12-01

50

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

51

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

Science.gov (United States)

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 fraction and, consequently, on the cosmic ray ionisation rate. Towards positions located close to the supernova remnant, we find cosmic ray ionisation rates much larger (?100) than those in standard galactic clouds. Conversely, towards one position situated at a larger distance, we derive a standard cosmic ray ionisation rate. Overall, these observations support the hypothesis that the ? rays observed in the region have a hadronic origin. In addition, based on CR diffusion estimates, we find that the ionisation of the gas is likely due to 0.1-1 GeV cosmic rays. Finally, these observations are also in agreement with the global picture of cosmic ray diffusion, in which the low-energy tail of the cosmic ray population diffuses at smaller distances than the high-energy counterpart.

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

2014-08-01

52

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

53

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

54

Cosmic-ray acceleration in supernova remnants  

CERN Document Server

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

Tatischeff, Vincent

2008-01-01

55

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the outer-shock structure of the oxygen-rich supernova remnant G292.0+1.8, using a deep observation with the Chandra X-ray Observatory. We measure radial variations of the electron temperature and emission measure that we identify as the outer shock propagating into a medium with a radially decreasing density profile. The inferred ambient density structure is consistent with models for the circumstellar wind of a massive progenitor star rather than for a uniform int...

Lee, Jae-joon; Park, Sangwook; Hughes, John P.; Slane, Patrick O.; Gaensler, B. M.; Ghavamian, Parviz; Burrows, David N.

2010-01-01

56

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

CERN Document Server

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

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

2009-01-01

57

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

58

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

59

Study of extragalactic supernova remnants  

International Nuclear Information System (INIS)

Image tube photographs of eight fields in the nearby spiral galaxy M31, using interference filters that isolate the emission lines of H? + [N II] at lambda 6570 A and [S II] at lambda 6725 A, have revealed nebulae that are believed to be supernova remnants (SNRs) in this galaxy. Spectroscopic observations have been used to confirm this identification for twelve of these nebulae. An estimate of the pressure in the optical filaments and the measured diameter permit an estimate of the initial energy in each remnant; a mean value of E0 approx. = 3 x 1050 ergs is found. However, the energy calculated in this way appears to be correlated with the remnant's diameter, an effect which may be related to magnetic pressure in the filaments. Comparison of the SNR spectra to shock wave models has allowed estimates of abundances of nitrogen, oxygen, and sulfur in the interstellar gas of M31. Eleven H II regions in M31 have been observed for comparison to the SNRs. Element abundances for these have been derived by an empirical method and are in substantial agreement with the abundances as derived from the SNRs. The variation of abundances as a function of galactocentric distance in M31 are found to be similar to the abundance gradients in our own Galaxy, with nitrogen and oxygen both decreasing by a factor of four or five from 4 to 23 Kpc. An emission region in the irregular galaxy NGC 4449 which is believed to be a very luminous, young SNR similar to the galac luminous, young SNR similar to the galactic remnant Cassiopeia A has been investigated. The absence of hydrogen in the oxygen rich knots suggets that nucleosynthesis has been important in the star that created this remnant

60

Spectrophotometry of galactic supernova remnants  

International Nuclear Information System (INIS)

Spectrophotometry of several galactic supernova remnants is presented and interpreted. High quality data for several filaments of the Cygnus Loop, IC443, and the Crab Nebula were obtained and are discussed in detail. Eight other galactic remnants including CTA1, CTB1, VRO 42.05.01, G206.9 + 2.3, the Monoceros Loop, OA184, and G56.3 + 5.7 were also studied but in less depth. It was found that IC433's spectra can be adequately matched using theoretical shock models which indicate V/sub s/ approx. 65 - 100 km s-1 and preshock densities of around 10 to 20 cm-3 using depleted elemental abundances. On the other hand, the Cygnus Loop's filaments exhibit a wide range of spectral line intensities which can not be fully described by these theoretical models. It is proposed discrepancies between the observed and the model calculated line intensities are due in part to the existence of an inhomogeneous interstellar medium. Small dense cloudlets embedded in an intercloud medium of lower density could produce both the range of observed spectral properties of the filaments as well as the large spatial scale for the stratification of emission line intensities. If the cloudlets are sufficiently small, then the resulting filaments will exhibit spectral lines characteristic of only a portion of a shock wave's cooling zone. The ability of the intercloud shock to flow around and advance past the cloudlets could lead to an enlarged ionization structure like the one obarged ionization structure like the one observed in the Cygnus Loop. The best known galactic SNR, the Crab Nebula, is distinctly unique among galactic remnants. This study increased significantly the amount of high quality spectral data for its filaments. The most interesting aspect of the investigation is that the filaments may not be chemically homogeneous, particularly in helium

 
 
 
 
61

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

62

Late-stage evolution of supernova remnants  

International Nuclear Information System (INIS)

The evolution of spherically-symmetric supernova remnants is examined by analytic and numerical means. The blast is assumed to take place in an homogeneous interstellar medium with a uniform density rho0 and an initially constant total energy E. An approximate representation of the radiative cooling is included, precipitating a thermal instability and producing a cold dense shell. The dynamical transition from adiabatic to radiation-dominated behavior is numerically simulated by a modified form of the von Neumann and Richtmeyer pseudo-viscosity method. The results obtained have resolved several theoretical questions regarding the late-stage evolution of supernova remnants, although the exact role of density inhomogeneities cannot be ascertained. In particular, it was found that (1) the time, shock radius, shock velocity, shock temperature, and remnant luminosity can be scaled according to different powers of E/rho0 and E rho02 and that the effective cooling rate or emissivity varies with the temperature T as T-5/8; (2) the thermal instability introduces a short-lived increase in the kinetic energy of the remnant while the internal energy drops catastrophically, although the ratio of kinetic to internal energy later becomes nearly constant; and (3) as E rho02 is increased, radiation assumes a more important role at a higher temperature and the remnant's dynamical behavior tends to the remnant's dynamical behavior tends to that of the idealized snowplow model

63

Supernovae, young remnants, and nucleosynthesis  

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

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

2011-01-01

65

Imaging of Kepler's supernova remnant  

International Nuclear Information System (INIS)

It is shown that the effects of crowding on images of Kepler's supernova remnant, that were obtained with the 3.6-m CFHT, can be greatly reduced by digitally subtracting a scaled continuum image from a narrow-band H-alpha + forbidden N II image. Attention is drawn to a narrow emission filament that extends for 27 arcsec along the western edge of the optical remnant. 9 refs

66

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The supernova remnant (SNR) N49 in the Large Magellanic Cloud has been observed with the Advanced CCD Imaging Spectrometer (ACIS) on board the {\\it Chandra X-Ray Observatory}. The superb angular resolution of the {\\it Chandra}/ACIS images resolves a point source, the likely X-ray counterpart of soft gamma-ray repeater SGR 0526$-$66, and the diffuse filaments and knots across the SNR. These filamentary features represent the blast wave sweeping through the ambient interstella...

Park, Sangwook; Burrows, David N.; Garmire, Gordon P.; Nousek, John A.; Hughes, John P.; Williams, Rosa Murphy

2002-01-01

67

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

68

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

CERN Document Server

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

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

2008-01-01

69

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

CERN Document Server

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

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

2007-01-01

70

Molecular clouds near supernova remnants  

International Nuclear Information System (INIS)

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

71

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

72

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

Science.gov (United States)

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

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

2014-01-01

73

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

74

THE OUTER SHOCK OF THE OXYGEN-RICH SUPERNOVA REMNANT G292.0+1.8: EVIDENCE FOR THE INTERACTION WITH THE STELLAR WINDS FROM ITS MASSIVE PROGENITOR  

International Nuclear Information System (INIS)

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

75

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

CERN Document Server

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

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

2010-01-01

76

The Supernova Remnant CTA 1  

Science.gov (United States)

The supernova remnants G327.1-1.1 and G327.4+0.4 (Kes 27) are located 1.5 deg apart in the constellation Norma. In 1980, Einstein IPC observations discovered that both were irregular filled-center X-ray sources with possible point sources superposed. This paper describes new ROSAT position sensitive proportional counter (PSPC) observations which both map the diffuse structure and clearly show several unresolved sources in each field. Both remnants have bright emitting regions inside the limb which might indicate the presence of high energy electrons accelerated by a pulsar. The interior region is more prominent in G327.1-1.1 than in Kes 27. The spectra are relatively strongly absorbed, as expected from distant remnants close to the galactic plane. Comparison of the X-ray and radio maps of each remnant allows us to attribute some emission to a shell and some to the interior. With this information, a blast-wave model is used to derive approximate ages and energy release. Indications are that the Kes 27 supernova deposited approximately 10(exp 51) ergs in the surrounding medium. The G327.1-1.1 event probably deposited a factor of 3-10 less.

Seward, Frederick D.

1996-01-01

77

Supernova Remnant in 3-D  

Science.gov (United States)

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

2009-01-01

78

Neutron Stars in Supernova Remnants and Beyond  

CERN Document Server

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

Gvaramadze, V V

2002-01-01

79

Supernova remnants and the origin of cosmic rays  

Science.gov (United States)

Supernova remnants have long been considered to be the dominant sources of Galactic cosmic rays. For a long time the prime evidence consisted of radio synchrotron radiation from supernova remnants, indicating the presence of electrons with energies of several GeV. However, in order to explain the cosmic ray energy density and spectrum in the Galaxy supernova remnant should use 10% of the explosion energy to accelerate particles, and about 99% of the accelerated particles should be protons and other atomic nuclei. Over the last decade a lot of progress has been made in providing evidence that supernova remnant can accelerate protons to very high energies. The evidence consists of, among others, X-ray synchrotron radiation from narrow regions close to supernova remnant shock fronts, indicating the presence of 10-100 TeV electrons, and providing evidence for amplified magnetic fields, gamma-ray emission from both young and mature supernova remnants. The high magnetic fields indicate that the condition for accelerating protons to >1015 eV are there, whereas the gamma-ray emission from some mature remnants indicate that protons have been accelerated.

Vink, Jacco

2014-01-01

80

Observing Supernovae and Supernova Remnants with JWST  

Science.gov (United States)

The James Webb Space Telescope (JWST) will enable near- and mid-infrared studies of supernovae (SN) and supernova remnants (SNR) in the Milky Way and galaxies throughout the local universe and to high redshift. JWST's instrumentation provides imaging, coronography, and spectroscopy (RSNR studies. JWST is a large aperture (6.5m), cryogenic, infrared-optimized space observatory under construction by NASA, ESA, and CSA for launch in 2018. The JWST observatory will be placed in an Earth-Sun L2 orbit by an Ariane 5 launch vehicle provided by ESA. The observatory is designed for a 5-year prime science mission, with consumables for 10 years of science operations. The first call for proposals for JWST observations will be released in 2017.

Sonneborn, George; Temim, Tea; Williams, Brian J.; Blair, William P.

2015-01-01

 
 
 
 
81

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

82

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

83

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

84

The molecular emission from old supernova remnants  

Science.gov (United States)

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 interstellar medium: 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 ?-ray emission in SNRs, a crucial step to answer questions related to cosmic rays population and acceleration.

Gusdorf, A.; Güsten, R.; Anderl, S.; Hezareh, T.; Wiesemeyer, H.

2014-01-01

85

Spitzer Observations of Molecular Hydrogen in Interacting Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

With Spitzer IRS we have obtained sensitive low-resolution spectroscopy from 5 to 35 microns for six supernova remnants (SNRs) that show evidence of shocked molecular gas: Kes 69, 3C 396, Kes 17, G346.6-0.2, G348.5-0.0 and G349.7+0.2. Bright, pure-rotational lines of molecular hydrogen are detected at the shock front in all remnants, indicative of radiative cooling from shocks interacting with dense clouds. We find the excitation of H2 S(0)-S(7) lines in these SNRs requires ...

Hewitt, John W.; Rho, Jeonghee; Andersen, Morten; Reach, William T.

2009-01-01

86

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

87

Cosmic ray acceleration in young supernova remnants  

CERN Document Server

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

Schure, K M

2013-01-01

88

Hot interstellar tunnels. I. Simulation of interacting supernova remnants  

International Nuclear Information System (INIS)

Reexamining a suggestion of Cox and Smith, we find that intersecting supernova remnants can indeed generate and maintain hot interstellar regions with napproximately-less-than10-2 cm-3 and Tapprox.106 K. These regions are likely to occupy at least 30% of the volume of a spiral arm near the midplane of the gaseous disk if the local supernova rate there is greater than 1.5 x 10-7 Myr-1 pc-3. Their presence in the interstellar medium is supported by observations of the soft X-ray background. The theory required to build a numerical simulation of interacting supernova remnants is developed. The hot cavities within a population of remnants will become connected for a variety of assumed conditions in the outer shells of old remnants. Extensive hot cavity regions or tunnels are built and enlarged by supernovae occurring in relatively dense gas which produce connections, but tunnels are kept hot primarily by supernovae occurring within the tunnels. The latter supernovae initiate fast shock waves which apparently reheat tunnels faster than they are destroyed by thermal conduction in a galactic magnetic field or by radiative cooling. However, the dispersal of these rejuvenating shocks over a wide volume is inhibited by motions of cooler interstellar gas in the interval between shocks. These motions disrupt the contiguity of the component cavities of a tunnel and may cause its death.The Monte Carlo simulations ind its death.The Monte Carlo simulations indicate that a quasi-equilibrium is reached within 107 years of the first supernova in a spiral arm. This equilibrium is characterized by a constant average filling fraction for cavities in the interstellar volume. Aspects of the equilibrium are discussed for a range of supernova rates. Two predictions of Cox and Smith are not confirmed within this range: critical growth of hot regions to encompass the entire medium, and the efficient quenching of a remnant's expansion by interaction with other cavities

89

$\\gamma$-ray production in supernova remnants  

CERN Document Server

The bulk of the cosmic rays up to about 100 TeV are thought to be accelerated by the 1st order Fermi mechanism at supernova shocks, producing a power-law spectrum. Both electrons and protons should be accelerated, but their ratio on acceleration is not well known. Recently, the EGRET instrument on the Compton Gamma Ray Observatory has observed supernova remnants IC 443 and gamma Cygni at GeV energies. On the assumption that the observed gamma-rays are produced by accelerated particles in the remnants (rather than, for example, from a central compact object) we model the contributions due to pion production, bremsstrahlung, and inverse Compton scattering on the cosmic microwave, diffuse galactic radiation, and locally produced radiation fields. We find that a spectral index of accelerated particles close to 2.4, and a ratio of electrons to protons in the range 0.2 to 0.3, gives a good fit to the observed spectra. We discuss the implications of this result for observations at air shower energies, and for the pr...

Gaisser, T K; Stanev, T

1996-01-01

90

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

Science.gov (United States)

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

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

1992-01-01

91

Filamentary structure of old optical supernova remnants  

International Nuclear Information System (INIS)

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

92

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.)

93

Reacceleration of electrons in supernova remnants  

Science.gov (United States)

Context. The radio spectra of many shell-type supernova remnants show deviations from those expected on theoretical grounds. Aims: 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 reacceleration can explain the observed variation in radio spectral indices. Methods: We explicitely calculated 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. After 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. Results: 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 calculated the radio spectral index and find that soft spectra with index ? ? - 0.6 can be maintained over more than 2 decades in radio frequency, even if the electrons experience reacceleration for only one acceleration time. A spectral hardening is possible but considerably more frequency-dependent. The spectral modification imposed by stochastic reacceleration downstream of the forward shock depends only weakly on the initial spectrum provided by, e.g., diffusive shock acceleration at the shock itself.

Pohl, M.; Wilhelm, A.; Telezhinsky, I.

2015-01-01

94

Multiwavelength investigation of the supernova remnant IC 443  

International Nuclear Information System (INIS)

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

95

Hydrodynamic instabilities in supernova remnants - Self-similar driven waves  

Science.gov (United States)

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

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

1992-01-01

96

On the radio spectra of supernova remnants  

Science.gov (United States)

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

2014-12-01

97

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

98

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

99

Nonthermal X-ray emission from young Supernova Remnants  

CERN Document Server

The cosmic-ray spectrum up to the knee ($E\\sim 10^{15}$ eV) is attributed to acceleration processes taking place at the blastwaves which bound supernova remnants. Theoretical predictions give a similar estimate for the maximum energy which can be reached at supernova remnant shocks by particle acceleration. Electrons with energies of the order $\\sim 10^{15}$ eV should give a nonthermal X-ray component in young supernova remnants. Recent observations of SN1006 and G347.3-0.5 confirm this prediction. We present a method which uses hydrodynamical simulations to describe the evolution of a young remnant. These results are combined with an algorithm which simultaneously calculates the associated particle acceleration. We use the test particle approximation, which means that the back-reaction on the dynamics of the remnant by the energetic particles is neglected. We present synchrotron maps in the X-ray domain, and present spectra of the energies of the electrons in the supernova remnant. Some of our results can be...

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

2000-01-01

100

On the morphology of supernova remnants  

International Nuclear Information System (INIS)

The difference in morphology between filled and shell type supernova remnants is attributed to differences in the activity of the neutron stars left by the supernovae. Pulsar activity leads to centrally concentrated remnants similar to the Crab. Non-activity as a pulsar results in all of the rotational energy loss going into dipole radiation. The pressure of this radiation creates shell-like objects with hollow interiors such as Cas A. (author)

 
 
 
 
101

3-D modeling of Type Ia supernova remnants  

Science.gov (United States)

It has been suggested that several features of observed Type Ia supernova remnants (SNRs) could not be easily explained by purely hydrodynamical models. Our work addresses that claim, using an exponential density profile to model a generic Type Ia SNR. In addition, we have run several simulations with different degrees of compressible fluid, to emulate efficient acceleration of cosmic rays. We find that many features of both Tycho's SNR and the remnant of SN 1006 can be explained purely by hydrodynamics: the close proximity of the forward and reverse shocks to the contact discontinuity, the appearance of ejecta structures in both remnants, and the protrusion of ejecta knots ahead of the forward shock. We also use these simulations to estimate the dynamical age of both remnants and to comment on key SNR parameters such as the ambient density and the energy of the explosion.

Warren, Donald; Blondin, John

102

A catalogue of 294 Galactic supernova remnants  

CERN Document Server

A revised catalogue of 294 Galactic supernova remnants (SNRs) is presented, along with some simple statistics. This catalogue has twenty more entries than did the previous version (from 2009), as 21 new remnants have been added, and one object has been removed as it has been identified as an HII region.

Green, D A

2014-01-01

103

Nonthermal X-ray emission from young Supernova Remnants  

Science.gov (United States)

The Galactic (nucleonic) cosmic-ray spectrum up to the knee (E ˜ 1015 eV) is believed to originate from acceleration processes occurring at supernova remnant shocks. This idea is confirmed by theoretical predictions, which give a similar estimate for the maximum particle energy, which can be reached at these shocks. Electrons with energies E ˜ 1014 eV radiate X-ray photons in the ˜ 10 - 100 µG magnetic fields present in many young supernova remnants. These electrons (near the knee), give rise to a nonthermal X-ray component in the spectrum of young supernova remnants. Recent observations of SN1006 and G347.3-0.5 show these nonthermal X-rays. We have combined hydrodynamical calculations of the evolution of a young remnant with an algorithm which simultaneously calculates the associated particle acceleration, in the test-particle approximation. We present the resulting synchrotron maps, at different Xray frequencies, and photon spectra of the synchrotron radiation. Our method allows for calculating photon and electron spectra at different regions within the remnant.

van der Swaluw, E.; Achterberg, A.

2001-08-01

104

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

105

Acceleration of cosmic rays and gamma-ray emission from supernova remnants in the Galaxy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Galactic cosmic rays are believed to be accelerated at supernova remnant shocks. Though very popular and robust, this conjecture still needs a conclusive proof. The strongest support to this idea is probably the fact that supernova remnants are observed in gamma-rays, which are indeed expected as the result of the hadronic interactions between the cosmic rays accelerated at the shock and the ambient gas. However, also leptonic processes can, in most cases, explain the observ...

Cristofari, P.; Gabici, S.; Casanova, S.; Terrier, R.; Parizot, E.

2013-01-01

106

Interacting supernova remnants: Tunnels in the sky  

International Nuclear Information System (INIS)

Two-dimensional calculations of near-surface, atmospheric nuclear fireballs and interacting supernova remnants (SNRs) are presented. The fireball calculations demonstrate the ability of the LASL program YAQUI to reproduce known time-dependent evolution of fireballs. The SNR calculation describes the interaction of two remnants aged 6400 and 32000 years. A dense plug is formed which separates the two cavity volumes. The combined volume of the cavities is 80% of the sum of the volumes of two isolated remnants but exceeds the union volume of two overlapping, noninteracting remnants. The resultant tunnel fraction is then greater than the value derived from simple considerations

107

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

108

X-ray synchrotron emission from supernova remnants  

CERN Document Server

X-ray synchrotron emission tells us of the highest energy reached by accelerated electrons. In a few supernova remnants (SN 1006, G347.3-0.5) this is the dominant form of X-ray radiation, but in most it is superposed to the dominant thermal emission. Thanks to the spectro-imaging capability of Chandra and XMM-Newton, X-ray synchrotron emission has now been unambiguously detected in most young supernova remnants (Cas A, Tycho, Kepler). It arises in a very thin shell (a few arcsecs) at the blast wave. The thinness of that shell (much broader in the radio domain) implies that the high energy electrons cool down very fast behind the shock. The magnetic field that one deduces from that constraint is more than 100 muG behind the shock.

Ballet, J

2005-01-01

109

Dust in historical Galactic Type Ia supernova remnants with Herschel  

Science.gov (United States)

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. Recently, large masses of newly formed dust have been discovered in the ejecta of core-collapse supernovae. Here, we present Herschel Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver (SPIRE) photometry at 70-500 ?m 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 ? and mass ?; this is spatially coincident with thermal X-ray emission and 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 ? with mass ?. Comparing the spatial distribution of the warm dust with X-rays from the ejecta and swept-up medium, and H? 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 mass ?0.07 M? as observed in core-collapse remnants of massive stars. Neither the warm or cold dust components detected here are spatially coincident with supernova ejecta material. We compare the lack of observed supernova dust with a theoretical model of dust formation in Type Ia remnants which predicts dust masses of 88(17) × 10-3 M? for ejecta expanding into ambient surrounding densities of 1(5) cm-3. The model predicts that silicon- and carbon-rich dust grains will encounter, at most, the interior edge of the observed dust emission at ˜400 years, confirming that the majority of the warm dust originates from swept-up circumstellar or interstellar grains (for Kepler and Tycho, respectively). The lack of cold dust grains in the ejecta suggests that Type Ia remnants do not produce substantial quantities of iron-rich dust grains and has important consequences for the 'missing' iron mass observed in ejecta. Finally, although, we cannot completely rule out a small mass of freshly formed supernova dust, the Herschel observations confirm that significantly less dust forms in the ejecta of Type Ia supernovae than in the remnants of core-collapse explosions.

Gomez, H. L.; Clark, C. J. R.; 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.

2012-03-01

110

X-Ray Measured Dynamics of Tycho's Supernova Remnant  

Science.gov (United States)

We present X-ray proper-motion measurements of the forward shock and reverse-shocked ejecta in Tycho's supernova remnant, based on three sets of archival Chandra data taken in 2000, 2003, and 2007. We find that the proper motion of the edge of the remnant (i.e., the forward shock and protruding ejecta knots) varies from 0.''20 yr-1 (expansion index m = 0.33, where R = tm ) to 0.''40 yr-1 (m = 0.65) with azimuthal angle in 2000-2007 measurements, and 0.''14 yr-1 (m = 0.26) to 0.''40 yr-1 (m = 0.65) in 2003-2007 measurements. The azimuthal variation of the proper motion and the average expansion index of [approx]0.5 are consistent with those derived from radio observations. We also find proper motion and expansion index of the reverse-shocked ejecta to be 0.''21-0.''31 yr-1 and 0.43-0.64, respectively. From a comparison of the measured m-value with Type Ia supernova evolutionary models, we find a pre-shock ambient density around the remnant of [less, similar]0.2 cm-3.

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

2010-01-01

111

Complex structure of the supernova remnant HB 3  

Science.gov (United States)

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.

Leahy, D. A.; Venkatesan, D.; Long, K. S.; Naranan, S.

1985-01-01

112

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

113

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

114

Non-thermal X-ray Emission from Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent studies of narrow, X-ray synchrotron radiating filaments surrounding young supernova remnants indicate that magnetic fields strengths are relatively high, B ~ 0.1 mG, or even higher, and that diffusion is close to the Bohm limit. I illustrate this using Cas A as an example. Also older remnants such as RCW 86 appear to emit X-ray synchrotron radiation, but the emission is more diffuse, and not always confined to a region close to the shock front. I argue that for RCW 8...

Vink, Jacco

2004-01-01

115

The acceleration of cosmic rays in supernova remnants  

International Nuclear Information System (INIS)

The idea that the bulk of cosmic rays below 10 GeV are accelerated in supernova remnants suggests that cosmic rays should also exhibit intensity variations on a scale comparable with the linear size of a representative remnant. Following the general spirit of shock-wave acceleration models, here Monte Carlo simulations are carried out to predict what this scale should be and then corroborative evidence is presented from an autocorrelation analysis of the COS B and SAS II ?-ray data for the latitude range |b|=10-200 ('near Galaxy') and |b| 0 ('far Galaxy'). (author)

116

Pulsar activity and supernova remnant morphology  

International Nuclear Information System (INIS)

The authors use the recently introduced concept of a 'window' of magnetic field strengths in which pulsars can be active to explain the variation in morphology of supernova remnants. Neutron stars created with field strengths of a value permitting pulsar activity result in particle production and Crab-like centrally concentrated remnants. Other field values lead to strong magnetic dipole radiation and consequent shell formation, e.g., Cas A. (Auth.)

117

Evolution of multiple supernova remnants  

Science.gov (United States)

Heating of the interstellar medium (ISM) by multiple supernova (SN) 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 filling the central region of starburst with hot gas, in order to launch vigorous outflows. We use hydrodynamical simulations to study the efficiency of multiple SNe in heating the ISM and filling the volume with gas of high temperatures. We argue that it is important for SN remnants to have a large filling factor and a large heating efficiency. For this, they have to be clustered in space and time, and keep exploding until the hot gas percolates through the whole region, in order to compensate for the radiative loss. In the case of a limited number of SNe, we find that although the filling factor can be large, the heating efficiency declines after reaching a large value. In the case of a continuous series of SNe, the hot gas (T ? 3 × 106 K) can percolate through the whole region after the total volume filling factor reaches a threshold of ˜0.3. The efficiency of heating the gas to X-ray temperatures can be ?0.1 after this percolation epoch, which occurs after a period of ?10 Myr for a typical starburst SN rate density of ?SN ? 10-9 pc-3 yr-1 and gas density of n ? 10 cm-3 in starburst nuclei regions. This matches the recent observations of a time delay of similar order between the onset of star formation and galactic outflows. The efficiency to heat gas up to X-ray temperatures (?106.5 K) roughly scales as ? _SN^{0.2} n^{-0.6}. For a typical SN rate density and gas density in starburst nuclei, the heating efficiency is ˜0.15, also consistent with previous interpretations from X-ray observations. We discuss the implications of our results with regard to observational diagnostics of ionic ratios and emission measures in starburst nuclei regions.

Vasiliev, Evgenii O.; Nath, Biman B.; Shchekinov, Yuri

2015-01-01

118

Nonuniform abundances in young supernova remnants  

International Nuclear Information System (INIS)

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

119

Near-Infrared Spectroscopy of Young Galactic Supernova Remnants  

CERN Document Server

Young Galactic supernova remnants (SNRs) are where we can observe closely the supernova (SN) ejecta and its interaction with circumstellar/interstellar medium. Therefore, they provide an opportunity to explore the explosion and the final stage of the evolution of massive stars. Near-infrared (NIR) emission lines in SNRs mostly originate from shocked dense material. In shocked SN ejecta, forbidden lines from heavy ions are prominent, while in shocked circumstellar/interstellar medium, [Fe II] and H2 lines are prominent. [Fe II] lines are strong in both media, and therefore [Fe II] line images provide a good starting point for the NIR study of SNRs. There are about twenty SNRs detected in [Fe II] lines, some of which have been studied in NIR spectroscopy. We will review the NIR [Fe II] observations of SNRs and introduce our recent NIR spectroscopic study of the young core-collapse SNR Cas A where we detected strong [P II] lines.

Koo, Bon-Chul

2015-01-01

120

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

 
 
 
 
121

GAMMA-RAY EMISSION FROM CRUSHED CLOUDS IN SUPERNOVA REMNANTS  

International Nuclear Information System (INIS)

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 blast wave 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 ?0-mesons produced in hadronic interactions between high-energy protons (nuclei) and gas in the compressed-cloud layer. This model provides a natural account of the observed synchrotron radiation in SNRs W51C, W44, and IC 443 with flat radio spectral index, which can be ascribed to a combination of secondary and reaccelerated electrons and positrons.

122

Chandra LETG Observations of Supernova Remnant 1987A  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2006-01-01

123

Neutron Star/Supernova Remnant Associations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The evidence for associations between neutron stars and supernova remnants is reviewed. After summarizing the situation for young radio pulsars, I consider the evidence from associations that young neutron stars can have properties very different from those of radio pulsars. This, though still controversial, shakes our simple perception of the Crab pulsar as prototypical of the young neutron star population.

Kaspi, V. M.

1999-01-01

124

Fermi LAT Observations of Supernova Remnants Interacting with Molecular Clouds  

CERN Document Server

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

Castro, Daniel

2010-01-01

125

Shock-Excited Maser Emission from Supernova Remnants: G32.8-0.1, G337.8-0.1, G346.6-0.2, and the HB3/W3 Complex  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present the results of VLA observations in the ground-state hydroxyl (OH) transition at 1720 MHz toward 20 supernova remnants (SNRs). We detect compact emission from four objects. For three of these objects (G32.8-0.1, G337.8-0.1, and G346.6-0.2), we argue that the emission results from masers which are shock-excited due to the interaction of the SNR and an adjacent molecular cloud. We observe a characteristic Zeeman profile in the Stokes V spectrum, which allows us to de...

Koralesky, Barron; Frail, D. A.; Goss, W. M.; Claussen, M. J.; Green, A. J.

1998-01-01

126

The Rediscovery of the Antlia Supernova Remnant  

Science.gov (United States)

While undertaking a survey of velocity-resolved diffuse optical emission from the [S II] 6716 A line with the Wisconsin H-alpha Mapper, we have rediscovered the Antlia Supernova remnant, a 26 degree diameter remmant near the Gum Nebula that was originally detected in SHASSA (Southern H-alpha Sky Survey Atlas) by P. McCullough in 2002. The original discovery showed this remnant was associated with ¼ keV X-ray emission in the ROSAT All-Sky Survey, and argued that Antlia was potentially the closest remnant to the Sun. We will present an analysis of the H-alpha and [S II] lines in this direction: the ratio of these lines indicate the shell is consistent with being a supernova remnant and the velocities allow us to constrain its age. We discuss this remnant in the context of the evolution of the entire Gum Nebula region, noting that its proximity and age make it possible to search for geochemical evidence of this remnant on Earth. This work was supported by the National Science Foundation's REU program through NSF Award AST-1004881.

Orchard, Alexander; Benjamin, Robert A.; Gostisha, Martin; Haffner, L. Matthew; Hill, Alex S.; Barger, Kathleen

2015-01-01

127

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

128

Extremely Fast Acceleration of Cosmic Rays in a Supernova Remnant  

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-10-23

129

Parametric studies of cosmic ray acceleration in supernova remnants  

CERN Document Server

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

Kosenko, D; Decourchelle, A

2014-01-01

130

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

CERN Document Server

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

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

2005-01-01

131

Non-thermal X-ray emission from young supernova remnants  

Science.gov (United States)

The Galactic (nucleonic) cosmic-ray spectrum up to the knee (E˜ 1015 eV) is attributed to acceleration processes that take place near the external shocks around supernova remnants (SNRs). Theoretical predictions based on the theory of diffusive shock acceleration give a similar estimate for the maximum particle energy that can be reached at these shocks: E ˜ 1014-1015 eV. Electrons with energies E ˜ 1014 eV radiate X-ray photons in the ˜10-100 ; ?G magnetic fields present in many young SNRs. These electrons near the knee give rise to a non-thermal X-ray component in the spectrum of young supernova remnants. Recent observations of SN1006 and G347.3-0.5 confirm this prediction. We have combined hydrodynamical calculations of the evolution of a young remnant with an algorithm that simultaneously calculates the acceleration of electrons, their radiation losses and the synchrotron spectrum of a young supernova remnant. The electrons are treated using a test-particle approximation. We give a semi-analytical estimate of the maximum electron energy and typical synchrotron frequencies for young remnants at the end of the free-expansion stage of their evolution. We present spectra of the energy distribution of the electrons in a young supernova remnant, and construct a synchrotron map in the X-ray domain, assuming Bohm diffusion within the remnant and a shock-compressed magnetic field.

van der Swaluw, E.; Achterberg, A.

2004-07-01

132

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.

133

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

Science.gov (United States)

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

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

2013-06-01

134

Dynamics of radiative supernova remnants  

International Nuclear Information System (INIS)

A high-resolution numerical simulation is used to study the evolution of a SNR evolving in a homogeneous uniform medium. Emphasis is placed on the transition from the adiabatic stage to the radiative pressure-driven snowplow stage, along with the possible further establishment of a momentum-conserving snowplow state. In most cases the momentum-conserving snowplow is found to be delayed beyond the merger of the remnant with the interstellar medium. 39 references

135

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present results from the observation of the young Galactic supernova remnant (SNR) G292.0+1.8 with the Advanced CCD Imaging Spectrometer (ACIS) on board the {\\it Chandra X-ray Observatory}. In the 0.3 $-$ 8 keV band, the high resolution ACIS images reveal a complex morphology consisting of knots and filaments, as well as the blast wave around the periphery of the SNR. We present equivalent width (EW) maps for the elemental species O, Ne, Mg, and Si, which allow us to iden...

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

2001-01-01

136

Central Compact Objects in Supernova Remnants  

CERN Document Server

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

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

2003-01-01

137

Using optical lines to study particle acceleration at supernova remnants  

CERN Document Server

The shocks of several young supernova remnants (SNR) are often associated with very thin optical filaments dominated by Balmer emission resulting from charge-exchange and collisional excitation between neutral Hydrogen from the interstellar medium and shocked protons and electrons. Optical lines are a direct probe of the conditions at the shock, in particular the width of the narrow and broad components reflect the temperature upstream and downstream of the shock, respectively. When the shock accelerate efficiently non-thermal particles, the shock structure changes producing anomalous Balmer lines and it is possible to use their line shape and their spatial profile to check the efficiency of SNR shocks in accelerating cosmic rays. Here we illustrate the kinetic theory of shock acceleration in presence of neutrals with some applications to young SNRs. We show that in three cases (RCW 86, SNR 0509-67.5 and Tycho) anomalous Balmer lines can be explained assuming that a fraction of $\\sim 10\\%$ of the total shock ...

Morlino, Giovanni

2014-01-01

138

The supernova remnant in 30 Dor B  

International Nuclear Information System (INIS)

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

139

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

140

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

 
 
 
 
141

Second Epoch Hubble Space Telescope Imaging of Kepler's Supernova Remnant  

Science.gov (United States)

We have obtained new HST/WFC3 images of Kepler's supernova remnant in H-alpha (F656N) and [N II] (F658N) emission line filters. The bright radiative shocks in dense clumps are detected in both filters, while non-radiative shocks are seen as faint filaments only in the H-alpha image. Most of these Balmer filaments lie around the periphery of the remnant where the blast wave encounters partially neutral interstellar gas. We compare the new images with HST/ACS images taken nearly 10 years previously, and find that these filaments tracing the forward shock have moved 0.6"-0.9" between the two epochs. Assuming a distance of 4 kpc to the remnant, these proper motions correspond to shock velocities of 1160-1740 km/s, which are consistent with the published values, 1550-2000 km/s (e.g. Blair et al. 1991, ApJ 366, 484). We also find a few Balmer filaments with highly non-radial proper motions. In one particularly interesting case in the projected interior of the remnant, SE of the center, the shock appears to have wrapped around a sharp density enhancement and moved about 0.3" in the period between the observations.The images allow us to study the evolution of the shock around an ejecta knot, which is punching through the remnant boundary in the northwest. The forward shock, visible as an arcuate Balmer filament, has moved about 1". At the trailing edges, the system of radiative knots formed by Rayleigh-Taylor instabilities have undergone significant changes - some knots have disappeared, new ones have appeared, and many have changed in brightness. Elsewhere in the remnant we find changes in the relative intensities of many small, bright knots over the 10 year baseline, indicating the short radiative lifetimes of these features.This work has been supported in part by grant HST-GO-12885 to the Universities Space Research Association.

Sankrit, Ravi; Blair, William P.; Borkowski, Kazimierz J.; Long, Knox S.; Patnaude, Daniel; Raymond, John C.; Reynolds, Stephen P.; Williams, Brian J.

2015-01-01

142

Nonthermal Emission from a Supernova Remnant in a Molecular Cloud  

CERN Document Server

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

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

2000-01-01

143

Neutron Star/supernova Remnant Associations  

Science.gov (United States)

We propose a new approach for studying the neutron star/supernova remnant associations, based on the idea that the (diffuse) supernova remnants (SNRs) can be products of an off-centred supernova (SN) explosion in a preexisting bubble created by the wind of a moving massive star. A cavity SN explosion of a moving star results in a considerable offset of the neutron star (NS) birth-place from the geometrical centre of the SNR. Therefore: a) the high transverse velocities inferred for a number of NSs (e.g. PSR B 1610-50, PSR B 1757-24, SGR 0525-66) through their association with SNRs can be reduced; b) the proper motion vector of a NS should not necessarily point away from the geometrical centre of the associated SNR. Taking into account of these two facts allow us to enlarge the circle of possible NS/SNR associations, and could significantly affect the results of previous studies of NS/SNR associations. The possibilities of our approach are illustrated with the example of the association between PSR B 1706-44 and SNR G 343.1-2.3. We show that this association could be real if both objects are the remnants of a SN exploded within a mushroom-like cavity (created by the SN progenitor wind breaking out of the parent molecular cloud and expanding into an intercloud medium of a much less density). We also show that the SN explosion sites in some middle-aged (shell-like) SNRs could be marked by (compact) nebulae of thermal X-ray emission. The possible detection of such nebulae within middle-aged SNRs could be used for the re-estimation of implied transverse velocities of known NSs or for the search of new stellar remnants possibly associated with these SNRs.

Gvaramadze, V. V.

144

Velocity and spectrum of the supernova remnant 30 Dor B  

International Nuclear Information System (INIS)

An analysis is presented of the spectrum of the supernova remnant 30 Doradus B (N175 B), within the 30 Dor B HII region in the Large Magellanic Cloud. The data yield a velocity dispersion estimate (>approximately 630 km s-1) and the size of the remnant (rsub(shock)0, such that E0/nsub(H) 50 erg cm3. Since nsub(H) approximately 40 cm-3 in the surrounding medium, the outburst energy E0 52 erg. A Type II classification accords with its association with Population I. In its radio and X-ray properties 30 Dor B resembles the Crab Nebula, but continuum emission from 30 Dor B correlates with H#betta# emission and is probably from two-photon hydrogen recombination. (author)

145

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

146

Spectrophotometry of supernovae and their remnants  

International Nuclear Information System (INIS)

Spectrophotometry of extragalactic supernovae shortly after discovery, and of galactic supernova remnants has been used to derive the masses, temperatures, compositions, and distances of supernovae. The Crab Nebula is shown to have a mass of ionized hydrogen in excess of 0.3 M/sub mass/, but no enrichment of oxygen, nitrogen, or sulfur. The Cygnus Loop is shown to emit [Fe XIV], indicating gas at 2 x 106 0K: this establishes the thermal nature of the x-ray emission, and casts doubt on the Loop's size and distance. Type II supernovae are shown to be consistent with a few solar masses of material at cosmic abundance. Their distances are found without reference to any other astronomical distance through a model of the expansion. Type I supernovae are shown to consist of about 1 solar mass of matter that may be 20 times enriched in iron, if the identification of [Fe II] lines at late stages is correct. (U.S.)

147

Spitzer Spectral Mapping of Supernova Remnant Cassiopeia A  

CERN Document Server

We present the global distribution of fine structure infrared line emission in the Cassiopeia A supernova remnant using data from the Spitzer Space Telescope's Infrared Spectrograph. We identify emission from ejecta materials in the interior, prior to their encounter with the reverse shock, as well as from the post-shock bright ring. The global electron density increases by >~100 at the shock to ~10^4 cm^-3, providing evidence for strong radiative cooling. There is also a dramatic change in ionization state at the shock, with the fading of emission from low ionization interior species like [SiII], giving way to [SIV] and, at even further distances, high-energy X-rays from hydrogenic silicon. Two compact, crescent-shaped clumps with highly enhanced neon abundance are arranged symmetrically around the central neutron star. These neon crescents are very closely aligned with the "kick" direction of the compact object from the remnant's expansion center, tracing a new axis of explosion asymmetry. They indicate tha...

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

2008-01-01

148

Molecular environment of semicircular composite supernova remnant 3C 396  

Science.gov (United States)

We investigate the molecular gas environment of the semicircular composite supernova remnant (SNR) 3C 396 in multiwavelengths. Our new 12 CO (J=1-0) and 13 CO (J=1-0) millimeter spectroscopic observations toward 3C 396 show a cavity-like structure roughly at VLSR = 67-72 km s-1 , in consistence with the suggestion by Lee et al. (2009) based on the Galactic Ring Survey 13 CO (J=1-0) data. However, we find that the molecular gas distribution at VLSR ˜ 84 km s-1 can also, and even better, explain the multiwavelength properties of the remnant. Around this LSR velocity, there is a molecular wall in the west of the SNR, which is coincident well with the bright X-ray, infrared, and radio emission along the western edge. The CO emission of the 84 km s-1 component fades out from west to east, indicating that the eastern region is of low gas density, accounting for the radio "blow-out" morphology in the east of the remnant. The broad red wing (86-92 km s-1 ) in the 12 CO (J=1-0) line profile for the eastern region of the remnant may be the kinematic evidence for shock-MC interaction. In particular, a finger/pillar-like molecular cloud (MC) of the component is revealed in the southwest (SW), with one end intruding inside the SNR border. The shock interaction with this "finger tip" can well explain the X-ray and radio enhancement in the SW and some infrared filaments there. The diffuse thermal X-ray emitting gas is found to be metal enriched except in the southwestern enhanced soft patch and be at low temperatures in the western shell of the remnant. We suggest that the 69 km s-1 MC is in the foreground based on HI self-absorption while the 84 km s-1 MC is associated with SNR 3C 396. This association implies that the supernova exploded near the eastern edge of the 84 km s-1 MC and place 3C 396 at a distance of 6.2 kpc (around the tangent point). In the western periphery of the remnant, the shock is most probably propagating in an inhomogeneous medium.

Su, Yang; Chen, Yang; Yang, Ji; Koo, Bon-Chul; Lu, Deng-Rong; Jeong, Il-Gyo; Delaney, Tracey

149

Supernovae. The bubble-like interior of the core-collapse supernova remnant Cassiopeia A.  

Science.gov (United States)

The death of massive stars is believed to involve aspheric explosions initiated by the collapse of an iron core. The specifics of these catastrophic explosions remain uncertain, due partly to limited observational constraints on asymmetries deep inside the star. Here we present near-infrared observations of the young supernova remnant Cassiopeia A, descendant of a type IIb core-collapse explosion, and a three-dimensional map of its interior unshocked ejecta. The remnant's interior has a bubble-like morphology that smoothly connects to and helps explain the multiringed structures seen in the remnant's bright reverse-shocked main shell of expanding debris. This internal structure may originate from turbulent mixing processes that encouraged outwardly expanding plumes of radioactive (56)Ni-rich ejecta. If this is true, substantial amounts of its decay product, (56)Fe, may still reside in these interior cavities. PMID:25635094

Milisavljevic, Dan; Fesen, Robert A

2015-01-30

150

Cosmic ray acceleration search in Supernova Remnants  

Science.gov (United States)

Galactic Supernova Remnants (SNRs) are among the best candidates as source of cosmic rays due to energetics, observed rate of explosion and as possible sites where the Fermi mechanisms naturally plays a key role. Evidence of hadronic acceleration processes taking place in SNRs are being collected with the Fermi-LAT, whose sensitivity in the range 100MeV-100GeV is crucial for disentangling possible hadronic contribution from inverse Compton or bremsstrahlung leptonic component. A survey of the detected SNRs will be given, focusing the attention on the role of the environment and the evolution stage of the SNR in the interpretation of the observed ?-ray spectra.

Giordano, Francesco; Di Venere, Leonardo

2014-11-01

151

Ultraviolet spectroscopy of the Vela supernova remnant  

CERN Document Server

A preliminary ultraviolet spectrum secured from the IUE satellite, of a bright filament in the Vela supernova remnant, displays both emission-line and continuum components. The emission-line spectrum shows the same anomalously low carbon-line strength reported previously for the Cygnus Loop. The continuum emission may be explained in terms of normal recombination processes in hydrogen and helium in a dense hot knot which dominates the field. The interpretation of the UV spectrum is supported by optical data for this region of Vela. (9 refs).

Danziger, I J; Wood, R

1980-01-01

152

Chandra LETG Observations of Supernova Remnant 1987A  

CERN Document Server

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

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

2006-01-01

153

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

0103$-$72.6, the second brightest X-ray supernova remnant (SNR) in the Small Magellanic Cloud (SMC), has been observed with the {\\it Chandra X-Ray Observatory}. Our {\\it Chandra} observation unambiguously resolves the X-ray emission into a nearly complete, remarkably circular shell surrounding bright clumpy emission in the center of the remnant. The observed X-ray spectrum for the central region is evidently dominated by emission from reverse shock-heated metal-rich ejecta. ...

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

2003-01-01

154

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

CERN Document Server

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

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

2013-01-01

155

A New Optical Sample of Supernova Remnants in M33  

Science.gov (United States)

We present a new and larger sample of supernova remnants in the nearby spiral galaxy M33. The sample is based upon CCD interference filter observations obtained with the Kitt Peak 4 m telescope and spectroscopic observations obtained with the Multiple Mirror Telescope. Using optical emission-line ratios, supplemented by a radio continuum map of M33 (Duric et al.; Gordon et al.), we have identified 98 supernova remnant (SNR) candidates, of which 53 were previously unknown. We have obtained spectra of 27 SNR candidates, bringing the total number of M33 SNRs for which spectra are available to 72. All the spectra show the characteristic signature of shock-heated gas, which leads us to believe that the rest of the candidates are also supernova remnants. The large sample provides a useful database to investigate the global properties of SNRs. In this paper, we present a new cumulative number-diameter [N(

Gordon, Shawn M.; Kirshner, Robert P.; Long, Knox S.; Blair, William P.; Duric, Nebojsa; Smith, R. Chris

1998-07-01

156

Distant Supernova Remnant Imaged by Chandra's High Resolution Camera  

Science.gov (United States)

The High Resolution Camera (HRC), one of the two X-ray cameras on NASA's Chandra X-ray Observatory, was placed into the focus for the first time on Monday, August 30. The first target was LMC X-1, a point-like source of X rays in the Large Magellanic Cloud. The Large Magellanic Cloud, a companion galaxy to the Milky Way, is 160,000 light years from Earth. After checking the focus with LMC X-1, Chandra observed N132D, a remnant of an exploded star in the Large Magellanic Cloud. "These were preliminary test observations," emphasized Dr. Stephen Murray, of the Harvard-Smithsonian Center for Astrophysics, principal investigator for the High Resolution Camera. "But we are very pleased with the results. All indications are that the HRC will produce X-ray images of unprecedented clarity." The N132D image shows a highly structured remnant, or shell, of 10-million-degree gas that is 80 light years across. Such a shell in the vicinity of the Sun would encompass more than fifty nearby stars. The amount of material in the N132D hot gas remnant is equal to that of 600 suns. The N132D supernova remnant appears to be colliding with a giant molecular cloud, which produces the brightening on the southern rim of the remnant. The molecular cloud, visible with a radio telescope, has the mass of 300,000 suns. The relatively weak x-radiation on the upper left shows that the shock wave is expanding into a less dense region on the edge of the molecular cloud. A number of small circular structures are visible in the central regions and a hint of a large circular loop can be seen in the upper part of the remnant. Whether the peculiar shape of the supernova remnant can be fully explained in terms of these effects, or whether they point to a peculiar cylindrically shaped explosion remains to be seen. -more- "The image is so rich in structure that it will take a while to sort out what is really going on," Murray said. "It could be multiple supernovas, or absorbing clouds in the vicinity of the supernova." The unique capabilities of the HRC stem from the close match of its imaging capability to the focusing power of the mirrors. When used with the Chandra mirrors, the HRC will make images that reveal detail as small as one-half an arc second. This is equivalent to the ability to read a stop sign at a distance of twelve miles. The checkout period for the HRC will continue for the next few weeks, during which time the team expects to acquire images of other supernova remnants, star clusters, and starburst galaxies. To follow Chandra's progress, visit the Chandra News Web site at: http://chandra.harvard.edu AND http://chandra.nasa.gov NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra X-ray Observatory for NASA's Office of Space Science, NASA Headquarters, Washington, D.C. The Smithsonian Astrophysical Observatory's Chandra X-ray Center in Cambridge, Mass., manages the Chandra science program and controls the observatory for NASA. TRW Space and Electronics Group of Redondo Beach, Calif., leads the contractor team that built Chandra. High resolution digital versions of the X-ray image (300 dpi JPG, TIFF) and other information associated with this release are available on the Internet at: http://chandra.harvard.edu/photo/0050/ or via links in: http://chandra.harvard.edu

1999-09-01

157

Synchrotron X-Ray Rims in Tycho's Supernova Remnant are Energy Dependent  

Science.gov (United States)

Several young supernova remnants exhibit thin X-ray bright rims of synchrotron radiation at their forward shocks. Thin rims have been taken to indicate that shock-accelerated electrons rapidly cool downstream of the shock, requiring strong magnetic field amplification. But, magnetic field damping immediately behind the shock could produce similarly thin rims. Synchrotron loss-limited rim widths should decrease with energy whereas damping limited rims should be relatively energy-independent. To discriminate between models, we measured rim widths around Tycho's supernova remnant in 5 energy bands using an archival 750 ks Chandra observation. Rims narrow with increasing energy, favoring loss-limited radiation over magnetic damping and corroborating similar observations in the remnant of SN 1006. Observed widths are best fit by electron transport models requiring amplified magnetic fields of ~200-1000 µG and particle diffusion coefficients ~1-100x Bohm values, consistent with prior work on Tycho's SNR. Non-negligible diffusion results in some degeneracy between magnetic field strength and diffusion coefficient in setting observed rim widths, but strong magnetic fields are required for all measurements. A different approach may be needed to better constrain diffusion at supernova remnant shocks.

Tran, Aaron; Williams, Brian J.; Petre, Robert; Ressler, Sean; Reynolds, Stephen P.

2015-01-01

158

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

159

The fate of supernova remnants near quiescent supermassive black holes  

CERN Document Server

There is mounting observational evidence that most galactic nuclei host both supermassive black holes (SMBHs) and young populations of stars. With an abundance of massive stars, core-collapse supernovae are expected in SMBH spheres of influence. We develop a novel numerical method, based on the Kompaneets approximation, to trace supernova remnant (SNR) evolution in these hostile environments, where radial gas gradients and SMBH tides are present. We trace the adiabatic evolution of the SNR shock until 50% of the remnant is either in the radiative phase or is slowed down below the SMBH Keplerian velocity and is sheared apart. In this way, we obtain shapes and lifetimes of SNRs as a function of the explosion distance from the SMBH, the gas density profile and the SMBH mass. As an application, we focus here exclusively on quiescent SMBHs, because their light may not hamper detections of SNRs and because we can take advantage of the unsurpassed detailed observations of our Galactic Centre. Assuming that propertie...

Rimoldi, Alex; Piran, Tsvi; Zwart, Simon Portegies

2015-01-01

160

Study on a faint nebula - the HB3 supernova remnant  

International Nuclear Information System (INIS)

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

 
 
 
 
161

CORRELATION OF SUPERNOVA REMNANT MASERS AND GAMMA-RAY SOURCES  

International Nuclear Information System (INIS)

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

162

Neutral hydrogen towards Tycho's supernova remnant  

International Nuclear Information System (INIS)

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

163

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

164

Observation of the Supernova Remnant IC 443 with VERITAS  

CERN Document Server

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

Humensky, T B

2007-01-01

165

HST/ACS Narrowband Imaging of the Kepler Supernova Remnant  

Science.gov (United States)

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

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

2007-01-01

166

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

CERN Document Server

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

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

2013-01-01

167

Spectra and energies of cosmic rays in young supernova remnants  

Science.gov (United States)

Cosmic ray acceleration in supernova remnants (SNRs) is attributed to the process of diffusive shock acceleration. The maximum energy to which the cosmic rays are accelerated in SNRs is believed to be around 1015 eV, close to the break ("knee") in the cosmic ray spectrum observed on Earth. Many models exist that treat cosmic ray acceleration in the steady state approximation. We will present our Monte Carlo method that follows particle acceleration over the life time of the SNR. This method shows that the maximum-attainable energy depends on the background into which the supernova explodes. Type Ia supernovae typically go off in a uniform-density medium, whereas many Type Ib/c-II explode into a medium with a ? ? r-2 density profile. We show that in the latter case much higher cosmic ray energies can be attained for the same explosion energy. Our method also allows us to extract cosmic ray spectra as a function of time and location in the SNR, as well as make X-ray synchrotron and pion-decay emissivity maps.

Schure, Klara; Achterberg, Bram; Keppens, Rony; Vink, Jacco

168

High-velocity gas associated with the supernova remnant S147  

International Nuclear Information System (INIS)

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

169

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.)

170

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)

171

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

172

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

173

The fate of supernova remnants near quiescent supermassive black holes  

Science.gov (United States)

There is mounting observational evidence that most galactic nuclei host both supermassive black holes (SMBHs) and young populations of stars. With an abundance of massive stars, core-collapse supernovae are expected in SMBH spheres of influence. We develop a novel numerical method, based on the Kompaneets approximation, to trace supernova remnant (SNR) evolution in these hostile environments, where radial gas gradients and SMBH tides are present. We trace the adiabatic evolution of the SNR shock until 50 per cent of the remnant is either in the radiative phase or is slowed down below the SMBH Keplerian velocity and is sheared apart. In this way, we obtain shapes and lifetimes of SNRs as a function of the explosion distance from the SMBH, the gas density profile and the SMBH mass. As an application, we focus here exclusively on quiescent SMBHs, because their light may not hamper detections of SNRs and because we can take advantage of the unsurpassed detailed observations of our Galactic Centre. Assuming that properties such as gas and stellar content scale appropriately with the SMBH mass, we study SNR evolution around other quiescent SMBHs. We find that, for SMBH masses over ˜107 M?, tidal disruption of SNRs can occur at less than 104 yr, leading to a shortened X-ray emitting adiabatic phase, and to no radiative phase. On the other hand, only modest disruption is expected in our Galactic Centre for SNRs in their X-ray stage. This is in accordance with estimates of the lifetime of the Sgr A East SNR, which leads us to expect one supernova per 104 yr in the sphere of influence of Sgr A*.

Rimoldi, A.; Rossi, E. M.; Piran, T.; Portegies Zwart, S.

2015-03-01

174

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

175

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

176

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

CERN Document Server

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

Badenes, Carles

2010-01-01

177

Radio emission from shell-type supernova remnants  

CERN Document Server

The evolution of the radio emission of shell-type Supernova remnants (SNRs) is modeled within the framework of the simple and commonly used assumptions that the mechanism of diffusive shock acceleration (DSA) is responsible for generating radio emitting electrons and that the magnetic field is the typical interstellar field compressed at the shock. It is considered that electrons are injected into the mechanism in test-particle regime directly from the high energy tail of the downstream Maxwellian distribution function. The model can be applied to most of the observed SNRs. It is shown that the model successfully explains the many averaged observational properties of evolved shell-type SNRs. In particular, the radio surface brightness ($\\Sigma$) evolves with diameter as $\\sim D^{-(0.3 \\div 0.5)}$, while the bounding shock is strong (Mach number is ${\\mathcal M} \\geq10$), followed by steep decrease (steeper than $\\sim D^{-4.5}$) for ${\\cal M} <10$. Such evolution of the surface brightness with diameter and ...

Asvarov, A

2006-01-01

178

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

179

Interstellar and Ejecta Dust in the Cas A Supernova Remnant  

Science.gov (United States)

The ejecta of the Cas A supernova remnant has a complex morphology, consisting of dense fast-moving line emitting knots and diffuse X-ray emitting regions that have encountered the reverse shock, as well as more slowly expanding, unshocked regions of the ejecta. Using the Spitzer 5-35 micron IRS data cube, and Herschel 70, 100, and 160 micron PACS data, we decompose the infrared emission from the remnant into distinct spectral components associated with the different regions of the ejecta. Such decomposition allows the association of different dust species with ejecta layers that underwent distinct nuclear burning histories, and determination of the dust heating mechanisms. Our decomposition identified three characteristic dust spectra. The first, most luminous one, exhibits strong emission features at approx. 9 and 21 micron, and a weaker 12 micron feature, and is closely associated with the ejecta knots that have strong [Ar II] 6.99 micron and [Ar III] 8.99 micron emission lines. The dust features can be reproduced by magnesium silicate grains with relatively low MgO-to-SiO2 ratios. A second, very different dust spectrum that has no indication of any silicate features, is best fit by Al2O3 dust and is found in association with ejecta having strong [Ne II] 12.8 micron and [Ne III] 15.6 micron emission lines. A third characteristic dust spectrum shows features that best matched by magnesium silicates with relatively high MgO-to-SiO2 ratio. This dust is primarily associated with the X-ray emitting shocked ejecta and the shocked interstellar/circumstellar material. All three spectral components include an additional featureless cold dust component of unknown composition. Colder dust of indeterminate composition is associated with [Si II] 34.8 micron emission from the interior of the SNR, where the reverse shock has not yet swept up and heated the ejecta. The dust mass giving rise to the warm dust component is about approx. 0.1solar M. However, most of the dust mass is associated with the unidentified cold dust component. Its mass could be anywhere between 0.1 and 1 solar M, and is primarily limited by the mass of refractory elements in the ejecta. Given the large uncertainty in the dust mass, the question of whether supernovae can produce enough dust to account for ISM dust masses in the local and high-z universe remains largely unresolved.

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

2013-01-01

180

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

 
 
 
 
181

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

182

New Radio Continuum, Hi, And X-ray Observations Of The Old Supernova Remnant Ctb80  

Science.gov (United States)

New radio continuum and HI line observations of the old supernova remnant CTB80 are analyzed. The radio continuum emission is more extended than previously known, and a 21cm absorption line profile is produced, which gives a revised distance to the supernova remnant and associated pulsar B1951+32. Archival ROSAT PSPC pointed observations of the CTB80 region are analyzed, and reveal extended X-ray emission associated the remnant over a large (1.2 degree) region. An analysis of the HI emission using the velocity channel maps confirms the inner shell found by Koo et al. (1990). In addition, an outer slowly moving shell centered on CTB80’s center, with radius 76 arcmin and velocity 40 km/s, is found. The shell’s size and velocity are not consistent with a stellar wind origin, but have properties consistent with what is expected for a cool dense shell behind the outer shock in the cooling (snowplow) phase of a supernova remnant. It is concluded from the radio and X-ray observations, that CTB80 is a large and old supernova remnant, with a slowly expanding snowplow-phase shell and a hot interior which is still emitting X-rays.

Leahy, Denis A.

2012-05-01

183

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

184

Expansion of the Optical Remnant from Tycho’s Supernova  

Science.gov (United States)

Tycho's supernova remnant (SNR) is the expanding remnant from SN 1572, the penultimate Galactic supernova to have been recorded by contemporary observers. Its optical light is almost exclusively faint hydrogen Balmer emission around the periphery of the SNR, produced where fast nonradiative shocks encounter partly neutral preshock interstellar material. A variety of filaments, presumably thin sheets oriented tangentially, surround about one-third of the radio/X-ray shell. We have used CCD images, taken from KPNO over seven epochs from 1986 to 2009, to give the first optical expansion measurement of Tycho's SNR of the CCD era. Thirty filaments were identified and measured; the majority of them are at or near the remnant's outer rim and have proper motions from 0.19?? ± 0.01?? yr-1 to 0.26?? ± 0.02?? yr-1. The associated expansion indices, defined as the ratio of the current expansion rate to the historical mean, range from 0.35 ± 0.03 to 0.52 ± 0.05. Our measurements are consistent with those from the classic study by Kamper & van den Bergh (1978, ApJ, 224, 851) for the same filaments, but the CCD measurements have higher precision, and we have measured several additional fainter filaments. For direct comparison with X-ray and radio measurements, we selected the subset of optical filaments lying exactly at the outer rim, as identified in Chandra and VLA images. Considering only these filaments, virtually all have expansion indices greater than 0.40, the Sedov value. In addition to the rim filaments, there are several seen in the interior (in projection) that have smaller proper motions; these may have been decelerated, and/or they could be directed non-tangentially. Our final epoch of images, taken from the 3.5m WIYN telescope in 2009, reveals previously undetected extremely faint optical emission surrounding well over half of the remnant shell. This newly detected faint emission agrees well with the limb as defined in X-ray and radio images.This work has been supported in part by NSF grant AST-098566.

Putko, Joseph; Winkler, P. Frank; Blair, William P.

2015-01-01

185

Shock-Excited Maser Emission from Supernova Remnants G32.8-0.1, G337.8-0.1, G346.6-0.2, and the HB3\\/W3 Complex  

CERN Document Server

We present the results of VLA observations in the ground-state hydroxyl (OH) transition at 1720 MHz toward 20 supernova remnants (SNRs). We detect compact emission from four objects. For three of these objects (G32.8-0.1, G337.8-0.1, and G346.6-0.2), we argue that the emission results from masers which are shock-excited due to the interaction of the SNR and an adjacent molecular cloud. We observe a characteristic Zeeman profile in the Stokes V spectrum, which allows us to derive a magnetic field of 1.5 and 1.7 mG for G32.8-0.1 and G346.6-0.2, respectively. The velocity of the masers also allows us to determine a kinematic distance to the SNR. Our criteria for a maser to be associated with an SNR along the line of sight are that the position and velocity of the maser and SNR must agree, and the OH(1720) emission must be unaccompanied by other OH lines.

Koralesky, B; Goss, W M; Claussen, M J; Green, A J; Koralesky, Barron

1998-01-01

186

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

International Nuclear Information System (INIS)

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

187

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

188

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

CERN Document Server

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

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

2011-01-01

189

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

190

Supernova Remnant W49B and Its Environment  

Science.gov (United States)

We study gamma-ray supernova remnant (SNR) W49B and its environment using recent radio and infrared data. Spitzer Infrared Spectrograph low resolution data of W49B shows shocked excitation lines of H2 (0,0) S(0)-S(7) from the SNR-molecular cloud interaction. The H2 gas is composed of two components with temperatures of ~260 K and ~1060 K, respectively. Various spectral lines from atomic and ionic particles are detected toward W49B. We suggest that the ionic phase has an electron density of ~500 cm-3 and a temperature of ~104 K by the spectral line diagnoses. The mid- and far-infrared data from MSX, Spitzer, and Herschel reveal a 151 ± 20 K hot dust component with a mass of 7.5 ± 6.6 × 10-4 M ? and a 45 ± 4 K warm dust component with a mass of 6.4 ± 3.2 M ?. 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 H I absorption spectra of W49B and four nearby H II regions (W49A, G42.90+0.58, G42.43-0.26, and G43.19-0.53) and study the relation between W49B and the surrounding molecular clouds by employing the 2.12 ?m infrared and CO data. We therefore obtain a kinematic distance of ~10 kpc for W49B and suggest that the remnant is likely associated with the CO cloud at about 40 km s-1.

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

2014-10-01

191

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

192

A New Evolutionary Phase of Supernova Remnant 1987A  

CERN Document Server

We have been monitoring the supernova remnant (SNR) 1987A with {\\it Chandra} observations since 1999. Here we report on the latest change in the soft X-ray light curve of SNR 1987A. For the last $\\sim$1.5 yr (since day $\\sim$8000), the soft X-ray flux has significantly flattened, staying (within uncertainties) at $f_{\\rm X}$ $\\sim$ 5.7 $\\times$ 10$^{-12}$ erg cm$^{-2}$ s$^{-1}$ (corresponding to $L_{\\rm X}$ $\\sim$ 3.6 $\\times$ 10$^{36}$ erg s$^{-1}$) in the 0.5--2 keV band. This remarkable change in the recent soft X-ray light curve suggests that the forward shock is now interacting with a decreasing density structure, after interacting with an increasing density gradient over $\\sim$10 yr prior to day $\\sim$8000. Possibilities may include the case that the shock is now propagating beyond a density peak of the inner ring. We briefly discuss some possible implications on the nature of the progenitor and the future prospects of our {\\it Chandra} monitoring observations.

Park, Sangwook; Burrows, David N; Racusin, Judith L; Dewey, Daniel; McCray, Richard

2011-01-01

193

A NEW EVOLUTIONARY PHASE OF SUPERNOVA REMNANT 1987A  

International Nuclear Information System (INIS)

We have been monitoring the supernova remnant (SNR) 1987A with Chandra observations since 1999. Here we report on the latest change in the soft X-ray light curve of SNR 1987A. For the last ?1.5 yr (since day ?8000), the soft X-ray flux has significantly flattened, staying (within uncertainties) at fX ? 5.7 x 10-12 erg cm-2 s-1 (corresponding to LX ? 3.6 x 1036 erg s-1) in the 0.5-2 keV band. This remarkable change in the recent soft X-ray light curve suggests that the forward shock is now interacting with a decreasing density structure, after interacting with an increasing density gradient over ?10 yr prior to day ?8000. Possibilities may include the case that the shock is now propagating beyond a density peak of the inner ring. We briefly discuss some possible implications on the nature of the progenitor and the future prospects of our Chandra monitoring observations.

194

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Deep optical CCD images of the supernova remnant G 32.8-0.1 were obtained where filamentary and diffuse emission was discovered. The images were acquired in the emission lines of Halpha+[N II] and [S II]. Filamentary and diffuse structures are detected in most areas of the remnant, while no significant [O III] emission is present. The flux-calibrated images suggest that the optical emission originates from shock-heated gas since the [S II]/Halpha ratio is greater than 1.2. T...

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

2009-01-01

195

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have carried out 12CO, 13CO, and C18O observations toward the mixed morphology supernova remnant (SNR) IC 443. The observations cover a 1.5*1.5 deg^2 area and allow us to investigate the overall molecular environment of the remnant. Some northern and northeastern partial shell structure of CO gas is around the remnant. One of the partial shells, about 5' extending beyond the northeastern border of the remnant's bright radio shell, seems to just confine the faint radio hal...

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

2014-01-01

196

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

International Nuclear Information System (INIS)

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

197

An Unbiased Far Ultraviolet Survey of Magellanic Cloud Supernova Remnants  

CERN Document Server

We have undertaken a FUSE survey of Magellanic Cloud supernova remnants, looking primarily for O VI and C III emission lines. Work in earlier cycles with FUSE indicates that optical and/or X-ray characteristics of supernova remnants are not always good predictors of the objects that will be bright and detectable in the UV. The goal of our survey is to test this concept by obtaining spectra of a random sample of Magellanic Cloud remnants with a broad range of radio, optical, and X-ray properties. Previously observed objects and remnants with known high extinction (or known high column densities) are the only objects eliminated from consideration. To date, we have clearly detected O VI emission from 12 of the 33 objects observed, with weak or marginal detections possible in a handful more.

Ghavamian, P; Sankrit, R; Danforth, C; Sembach, K; Ghavamian, Parviz; Blair, William P.; Sankrit, Ravi; Danforth, Charles; Sembach, Kenneth

2004-01-01

198

Radio and Optical Properties of Supernova Remnants in M33  

Science.gov (United States)

Although the properties and evolution of supernova remnants (SNRs) are generally understood, there are important questions concerning the interaction of SNRs with the interstellar medium. These include the role of SNRs in regulating the relativistic gas (cosmic rays) in galaxies and the degree to which the ISM affects the evolution of SNRs. Statistically significant samples of SNRs observed at several wavelengths have the potential for yielding valuable insight into these questions. To this end, we are carrying out a search for SNRs in the galaxy M33 at optical, radio and X-ray wavelengths. M33 is ideally suited for a study of this nature. Remnants will all be at essentially the same distance and, because M33 is nearly face on, the effects due to interstellar absorption are reduced. Furthermore, M33 is a spiral galaxy, allowing for comparisons with the Milky Way. We have undertaken new radio, X-ray and optical observations of M33, and, here, we present the sample of radio selected and optically confirmed SNRs and discuss some of the results. We have identified ~ 100 non-thermal radio sources within 20arcmin of the center of M33. Many of these sources are likely to be SNRs, and we have made followup spectroscopic observations of these candidates with the MMT and have found many to be associated with shock-heated gas. This radio-selected sample has the advantage over previous optical samples of M33 in that it can detect remnants in highly optically confused regions. As an example, we have identified a SNR located in the giant HII region NGC-592 in M33 (Gordon et al., 1993 Ap. J., in press). This is a particularly interesting HII region because a soft X-ray source is located in it. We found a knot of non-thermal radio emission at the site of the X-ray source and detected shock-heated gas at optical wavelengths thus showing that the X-ray emission is associated with an embedded SNR.

Gordon, S.; Kirshner, R.; Duric, N.; Long, K.

1993-12-01

199

Searches for continuous gravitational waves from nine young supernova remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We describe directed searches for continuous gravitational waves in data from the sixth LIGO science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of ten. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The s...

Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.

2014-01-01

200

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

 
 
 
 
201

SUPERNOVA REMNANT PROGENITOR MASSES IN M31  

International Nuclear Information System (INIS)

Using Hubble Space Telescope photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main-sequence masses (MZAMS) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and employ CMD fitting to measure the recent star formation history of the regions surrounding cataloged SNR sites. We identify any young coeval population that likely produced the progenitor star, then assign an age and uncertainty to that population. Application of stellar evolution models allows us to infer the MZAMS from this age. Because our technique is not contingent on identification or precise location of the progenitor star, it can be applied to the location of any known SNRs. We identify significant young star formation around 53 of the 59 SNRs and assign progenitor masses to these, representing a factor of ?2 increase over currently measured progenitor masses. We consider the remaining six SNRs as either probable Type Ia candidates or the result of core-collapse progenitors that have escaped their birth sites. In general, the distribution of recovered progenitor masses is bottom-heavy, showing a paucity of the most massive stars. If we assume a single power-law distribution, dN/dM?M?, then we find a distribution that is steeper than a Salpeter initial mass function (IMF) (? = –2.35). In particular, we find values of ? outside the range –2.7 ? ? ? –4.the range –2.7 ? ? ? –4.4 to be inconsistent with our measured distribution at 95% confidence. If instead we assume a distribution that follows a Salpeter IMF up to some maximum mass, then we find that values of MMax > 26 are inconsistent with the measured distribution at 95% confidence. In either scenario, the data suggest that some fraction of massive stars may not explode. The result is preliminary and requires more SNRs and further analysis. In addition, we use our distribution to estimate a minimum mass for core collapse between 7.0 and 7.8 M?.

202

SUPERNOVA REMNANT PROGENITOR MASSES IN M31  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-12-10

203

The fate of supernova remnants near quiescent supermassive black holes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There is mounting observational evidence that most galactic nuclei host both supermassive black holes (SMBHs) and young populations of stars. With an abundance of massive stars, core-collapse supernovae are expected in SMBH spheres of influence. We develop a novel numerical method, based on the Kompaneets approximation, to trace supernova remnant (SNR) evolution in these hostile environments, where radial gas gradients and SMBH tides are present. We trace the adiabatic evolu...

Rimoldi, Alex; Rossi, Elena M.; Piran, Tsvi; Zwart, Simon Portegies

2015-01-01

204

A Search for Fallback Disks in Four Young Supernova Remnants  

CERN Document Server

We report on our search for the optical/infrared counterparts to the central compact objects in four young supernova remnants: Puppis A, PKS 1209-52, RCW 103, and Cassiopeia A. The X-ray point sources in these supernova remnants, likely members of a new class (or classes) of young neutron stars, are attractive targets for probing the existence of supernova ``fallback'' disks. Such disks, which are a general prediction of many supernova models, can form from supernova ejecta that fails to reach escape velocity during the initial explosion. Irradiation of the disk by a central X-ray source may lead to detectable optical/infrared emission from such a disk. We used imaging observations from ground-based telescopes in the optical and near-infrared regimes and from the Spitzer Space Telescope at 4.5 and 8.0 micron, to search for optical/infrared counterparts at the X-ray point source positions measured in these supernova remnants by the Chandra X-Ray Observatory. We did not detect any counterparts, and hence find n...

Wang, Z; Chakraborty, D; Wang, Zhongxiang; Kaplan, David L.; Chakrabarty, Deepto

2006-01-01

205

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

206

Turbulent Magnetic Field Amplification and X-ray Synchrotron Radiation in Shell-Type Supernova Remnants  

Science.gov (United States)

I will present evidence for turbulent magnetic field amplification in Cassiopeia A, particle acceleration in IC 443 and limits on X-ray synchrotron radiation from a number of other shell-type supernova remnants. I will also discuss the implications of these results to the current picture of supernova remnant evolution and the origin of the cosmic rays. When a deep ROSAT HRI image of Cas A is de-absorbed using H I and OH radio absorption data, it becomes well-correlated with radio continuum maps. This strong point-by-point correlation is consistent with equipartition between the magnetic field and hot gas -- implying that Cas A's plasma is fully turbulent and continuously amplifying the magnetic field. X-ray imaging spectroscopy of IC 443, with the ASCA satellite, reveals two regions of particularly hard emission: an unresolved source embedded in an extended emission region, and a ridge of emission coincident with the southeastern rim. Both features are located on part of the radio shell where the shock wave is interacting with molecular gas, and together they account for a majority of the emission at 7 keV. I will argue that the features are most likely tracing enhanced particle acceleration by shocks that are formed as the supernova blast wave impacts the ring of molecular clouds. In addition to IC 443, I will discuss the likelihood that the hard X-ray emission from a number of other shell-type galactic supernova remnants may be of synchrotron origin. On one hand, these results imply that X-ray synchrotron radiation exists, and must be considered when conducting a program in X-ray spectroscopy. On the other hand, upper limits on radio to X-ray break frequencies also suggest that, while supernova shocks can explain the origin of cosmic rays up to the ``knee,'' it is still unclear whether they account for the highest energy Galactic cosmic rays.

Keohane, J. W.

1997-12-01

207

Supernova Remnants and Star Formation in the Large Magellanic Cloud  

Science.gov (United States)

It has often been suggested that supernova remnants (SNRs) can trigger star formation. To investigate the relationship between SNRs and star formation, we have examined the known sample of 45 SNRs in the Large Magellanic Cloud (LMC) to search for associated young stellar objects (YSOs) and molecular clouds. We find seven SNRs associated with both YSOs and molecular clouds, three SNRs associated with YSOs but not molecular clouds, and eight SNRs near molecular clouds but not associated with YSOs. Among the 10 SNRs associated with YSOs, the association between the YSOs and SNRs either can be rejected or cannot be convincingly established for eight cases. Only two SNRs have YSOs closely aligned along their rims; however, the time elapsed since the SNR began to interact with the YSOs' natal clouds is much shorter than the contraction timescales of the YSOs, and thus we do not see any evidence of SNR-triggered star formation in the LMC. The 15 SNRs that are near molecular clouds may trigger star formation in the future when the SNR shocks have slowed down to <45 km s-1. We discuss how SNRs can alter the physical properties and abundances of YSOs.

Desai, Karna M.; Chu, You-Hua; Gruendl, Robert A.; Dluger, William; Katz, Marshall; Wong, Tony; Chen, C.-H. Rosie; Looney, Leslie W.; Hughes, Annie; Muller, Erik; Ott, Jürgen; Pineda, Jorge L.

2010-08-01

208

Supernova 1987A: A young supernova remnant in an aspherical progenitor wind  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The interaction between the ejecta from Supernova 1987A and surrounding material is producing steadily brightening radio and X-ray emission. The new-born supernova remnant has been significantly decelerated by this interaction, while its morphology reflects the axisymmetric nature of the progenitor wind.

Gaensler, B. M.; Manchester, R. N.; Staveley-smith, L.; Wheaton, V.; Tzioumis, A. K.; Reynolds, J. E.; Kesteven, M. J.

1999-01-01

209

X-ray spectra of supernova remnants  

International Nuclear Information System (INIS)

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

210

Observations of Supernova Remnants with the Einstein Observatory  

International Nuclear Information System (INIS)

As for almost any other aspect of X-ray astronomy, the sensitivity, the arcsecond angular resolution and the spectral resolution achieved with the Einstein Observatory are giving new surprising results in the observation of Supernova Remnants (SNR's). We will concentrate here on the results obtained with the imaging experiments on the galactic SNR's. (orig.)

211

Multiwavelength comparison of Cassiopeia A and Tycho's supernova remnant  

International Nuclear Information System (INIS)

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

212

Exploring the supernova remnant G308.4-1.4  

CERN Document Server

Aims: We present a detailed X-ray and radio wavelength study of G308.4-1.4, a candidate supernova remnant (SNR) in the ROSAT All Sky Survey and the MOST supernova remnant catalogue. Methods: The SNR candidate and its central point sources were studied using observations from the Chandra X-ray Observatory, SWIFT, the Australian Telescope Compact Array (ATCA) at 1.4 and 2.5 GHz and WISE infrared observation at 24 $\\mu$m. Results: We conclude that G308.4-1.4 is indeed a supernova remnant by means of its morphology matching at X-ray, radio and infrared wavelength, its spectral energy distribution in the X-ray band and its emission characteristics in the radio band. G308.4-1.4 is a shell-type SNR. X-ray, radio and infrared emission is seen only in the eastern part of the remnant due to a strong spatial density variation of the interstellar medium around the remnant. The X-ray emission can best be described by an absorbed non-equilibrium collisional plasma with a hydrogen density of $n_\\text{H}=(1.02\\pm 0.04)$ cm$^...

Prinz, Tobias

2012-01-01

213

First optical detection from the supernova remnant G 15.1-1.6  

CERN Document Server

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

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

2008-01-01

214

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

CERN Document Server

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

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

1997-01-01

215

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

International Nuclear Information System (INIS)

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

216

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

217

No cold dust within the supernova remnant Cassiopeia A  

Science.gov (United States)

A large amount (about three solar masses) of cold (18K) dust in the prototypical type II supernova remnant Cassiopeia A was recently reported. It was concluded that dust production in type II supernovae can explain how the large quantities (~ 108 solar masses) of dust observed in the most distant quasars could have been produced within only 700 million years after the Big Bang. Foreground clouds of interstellar material, however, complicate the interpretation of the earlier submillimetre observations of Cas A. Here we report far-infrared and molecular line observations that demonstrate that most of the detected submillimetre emission originates from interstellar dust in a molecular cloud complex located in the line of sight between the Earth and Cas A, and is therefore not associated with the remnant. The argument that type II supernovae produce copious amounts of dust is not supported by the case of Cas A, which previously appeared to provide the best evidence for this possibility.

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

2004-12-01

218

No cold dust within the supernova remnant Cassiopeia A  

CERN Document Server

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

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

2004-01-01

219

Thermal X-ray Emission and Cosmic Ray Production in Young Supernova Remnants  

CERN Document Server

We have developed a simple model to investigate the modifications of the hydrodynamics and non-equilibrium ionization X-ray emission in young supernova remnants due to nonlinear particle acceleration. In nonlinear, diffusive shock acceleration, the heating of the gas to X-ray emitting temperatures is strongly coupled to the acceleration of cosmic ray ions. If the acceleration is efficient and a significant fraction of the shock ram energy ends up in cosmic rays, compression ratios will be higher and the shocked temperature lower than test-particle, Rankine-Hugoniot relations predict. In this Letter, we show that typical parameters of young supernova remnants should result in significant nonlinear acceleration, which strongly modifies the hydrodynamics and consequently the thermal X-ray emission. We illustrate how particle acceleration impacts the interpretation of X-ray data using the X-ray spectra of Kepler's remnant, observed by {\\it ASCA} and {\\it RXTE}. We show that thermal X-ray emission provides importa...

Decourchelle, A; Ballet, J

2000-01-01

220

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

 
 
 
 
221

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

222

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

International Nuclear Information System (INIS)

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 ?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 ?m, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

223

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

224

G306.3-0.9: A Newly Discovered Young Galactic Supernova Remnant  

Science.gov (United States)

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 160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24µm, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

Reynolds, Mark T.; Loi, Syheh T.; Murphy, Tara; Miller, Jon M.; Maitra, Dipankar; Gueltekin, Kayhan; Gehrels, Neil; Kennea, Jamie A.; Siegel, Michael H.; Gelbord, Jonathan; Kuin, Paul; Moss, Vanessa; Reeves, Sarah; Robbins, William J.; Gaensler, B. M.; Reis, Rubens C.; Petre, Robert

2013-01-01

225

The Bubble-like Interior of the Core-Collapse Supernova Remnant Cassiopeia A  

CERN Document Server

The death of massive stars is believed to involve aspheric explosions initiated by the collapse of an iron core. The specifics of how these catastrophic explosions proceed remain uncertain due, in part, to limited observational constraints on various processes that can introduce asymmetries deep inside the star. Here we present near-infrared observations of the young Milky Way supernova remnant Cassiopeia A, descendant of a type IIb core-collapse explosion, and a three-dimensional map of its interior, unshocked ejecta. The remnant's interior has a bubble-like morphology that smoothly connects to and helps explain the multi-ringed structures seen in the remnant's bright reverse shocked main shell of expanding debris. This internal structure may have originated from turbulent mixing processes that encouraged the development of outwardly expanding plumes of radioactive 56Ni-rich ejecta. If this is true, substantial amounts of its decay product, 56Fe, may still reside in these interior cavities.

Milisavljevic, Dan

2015-01-01

226

Remnant of the monoceros loop supernova at decametric waves  

International Nuclear Information System (INIS)

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

227

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

228

A Newly Recognized Very Young Supernova Remnant in M83  

Science.gov (United States)

As part of a spectroscopic survey of supernova remnant candidates in M83 using the Gemini-South telescope and GMOS, we have discovered one object whose spectrum shows very broad lines at Halpha, [O I] 6300, and [O III] 5007, similar to those from other objects classified as `late time supernovae.' Although six historical supernovae have been observed in M83 since 1923, none were seen at the location of this object. Hubble Space Telescope Wide Field Camera 3 images show a nearly unresolved emission source, while Chandra and ATCA data reveal a bright X-ray source and nonthermal radio source at the position. Objects in other galaxies showing similar spectra are only decades post-supernova, which raises the possibility that the supernova that created this object occurred during the last century but was not observed. Using photometry of nearby stars from the HST data, we suggest the precursor was at least 17 M(sun), and the presence of broad Halpha in the spectrum makes a type II supernova likely. The supernova must predate the 1983 VLA radio detection of the object. We suggest examination of archival images of M83 to search for evidence of the supernova event that gave rise to this object, and thus provide a precise time since the explosion.We acknowledge STScI grants under the umbrella program ID GO-12513 to Johns Hopkins University, STScI, and Middlebury College. PFW acknowledges additional support from the National Science Foundation through grant AST-0908566.

Blair, William P.; Winkler, P. Frank; Long, Knox S.; Whitmore, Bradley C.; Kim, Hwihyun; Soria, Roberto; Kuntz, K. D.; Plucinsky, Paul P.; Dopita, Michael A.; Stockdale, Christopher

2015-01-01

229

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

230

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

International Nuclear Information System (INIS)

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

231

Infrared Echoes near the Supernova Remnant Cassiopeia A  

CERN Document Server

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

Krause, O; Birkmann, S M; Le Floc'h, E; Gordon, K D; Egami, E; Bieging, J H; Hughes, J P; Young, E T; Hinz, J L; Quanz, S P; Hines, D C

2005-01-01

232

A Compact Central Object in the Supernova Remnant Kes 79  

CERN Document Server

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

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

2003-01-01

233

X-ray spectroscopic observations and modeling of supernova remnants  

International Nuclear Information System (INIS)

The X-ray observations of young remnants and their theoretical interpretation are described. A number of questions concerning the nature of the blast wave interaction with the interstellar gas and grains and of atomic processes in these hot plasmas are considered. It is concluded that future X-ray spectrometers with high collecting area, moderate spectral resolution and good spatial resolution can make important contributions to the understanding of supernova remnants in the Milky Way and neighboring galaxies and of their role in the global chemical and dynamical evolution of the interstellar medium

234

Nonthermal radiation from supernova remnants in the adiabatic stage of evolution  

International Nuclear Information System (INIS)

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

235

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

236

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

International Nuclear Information System (INIS)

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

237

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

CERN Document Server

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

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

2006-01-01

238

The optical emission from the supernova remnant HB 3  

Science.gov (United States)

The supernova remnant HB 3 was first detected as a radio source by Brown and Hazard (1953). On the basis of subsequent radio studies, it was concluded that the object was a supernova remnant (SNR). HB 3 is located at the far western edge of the H II region/molecular cloud complex W3-W4-W5 (IC 1795-1805-1848). However, a physical association of HB 3 with this complex is uncertain. In the present investigation, attention is called to the probability that HB 3 exhibits a more extensive optical emission structure than previously realized, and one which agrees well with both the position and morphology of the radio emission. It is found that narrow-passband optical images strongly suggest an almost complete optical emission shell for HB 3. Spectroscopic observations are, however, required to confirm that this emission is characteristic of a SNR.

Fesen, R. A.; Gull, T. R.

1983-01-01

239

Understanding hadronic gamma-ray emission from supernova remnants  

Energy Technology Data Exchange (ETDEWEB)

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.

Damiano, Caprioli, E-mail: caprioli@arcetri.astro.it [INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, Firenze (Italy)

2011-05-01

240

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

 
 
 
 
241

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_\

Arnaud, M

2014-01-01

242

Kinematic detection of supernova remnants in giant H II regions  

International Nuclear Information System (INIS)

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

243

Galactic Propagation of Cosmic Rays from Individual Supernova Remnants  

CERN Document Server

It is widely believed that supernova remnants are the best candidate sources for the observed cosmic ray flux up to the knee, i.e. up to ~PeV energies. Indeed, the gamma-ray spectra of some supernova remnants can be well explained by assuming the decay of neutral pions which are created in hadronic interactions. Therefore, fitting the corresponding gamma spectra allows us to derive the spectra of cosmic rays at the source which are locally injected into our Galaxy. Using these spectra as a starting point, we propagate the cosmic rays through the Galaxy using the publicly available GALPROP code. Here, we will present first results on the contribution of those SNRs to the total cosmic ray flux and discuss implications.

Nierstenhoefer, Nils; Schuppan, Florian; Tjus, Julia Becker

2015-01-01

244

Properties of Optically Selected Supernova Remnant Candidates in M33  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Narrow band images covering strong emission lines are efficient to survey supernova remnants (SNRs) in nearby galaxies. Using the narrow band images provided by the Local Group Galaxy Survey we searched for SNRs in M33. Culling the objects with enhanced [SII]/Ha and round morphology in the continuum-subtracted Ha and [SII] images, we produce a list of 199 sources. Among them 79 are previously unknown. Their progenitor and morphology types were classified. A majority of the s...

Lee, Jong Hwan; Lee, Myung Gyoon

2014-01-01

245

On the spherical-axial transition in supernova remnants  

Science.gov (United States)

A new law of motion for supernova remnant (SNR) which introduces the quantity of swept matter in the thin layer approximation is introduced. This new law of motion is tested on 10 years observations of SN 1993J. The introduction of an exponential gradient in the surrounding medium allows to model an aspherical expansion. A weakly asymmetric SNR, SN 1006, and a strongly asymmetric SNR, SN 1987A, are modeled. In the case of SN 1987A the three observed rings are simulated.

Zaninetti, L.

2012-02-01

246

Radio emission from supernova remnants in the galaxy M33  

International Nuclear Information System (INIS)

A new 21-cm map of M33 with a resolution of 25 x 49 arcsec (RA, Dec) and an rms noise of 0.2 mJy per beam area has been used to search for radio emission at the positions of optically identified supernova remnants (SNR). Five well-established and three probable radio identifications are found. In the surface brightness-diameter diagram, the M33 radio remnants agree well with galactic objects. Using the galactic relation as a reference an average distance to M33 of 830 +- 100 kpc is derived. It is estimated that most of the radio remnants in M33 with flux densities > 1 mJy at 21 cm have been optically identified. (author)

247

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

248

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ra...

Reynolds, Mark; Loi, Shyeh; 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

2013-01-01

249

Supernova Remnant 1987A: The Latest Report from the Chandra X-Ray Observatory  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We continue monitoring supernova remnant (SNR) 1987A with the {\\it Chandra X-ray Observatory}. As of 2004 January, bright X-ray spots in the northwest and the southwest are now evident in addition to the bright eastern ring. The overall X-ray spectrum, Since 2002 December, can be described by a planar shock with an electron temperature of $\\sim$2.1 keV. The soft X-ray flux is now 8 $\\times$ 10$^{-13}$ ergs cm$^{-2}$ s$^{-1}$, which is about five times higher than four years ...

Park, Sangwook; Zhekov, Svetozar A.; Burrows, David N.; Garmire, Gordon P.; Mccray, Dick

2005-01-01

250

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

Science.gov (United States)

MSH 1556 (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; Slane, Patrick; Castro, Daniel; Plucinsky, Paul; Gelfand, Joseph; Dickel, John R.

2013-01-01

251

Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets and Supernova Remnants  

Science.gov (United States)

We performed numerical simulations of particle acceleration, magnetic field generation, and emission from shocks in order to understand the observed emission from relativistic jets and supernova remnants. The investigation involves the study of collisionless shocks, where the Weibel instability is responsible for particle acceleration as well as magnetic field generation. A 3-D relativistic particle-in-cell (RPIC) code has been used to investigate the shock processes in electron-positron plasmas. The evolution of theWeibe1 instability and its associated magnetic field generation and particle acceleration are studied with two different jet velocities (0 = 2,5 - slow, fast) corresponding to either outflows in supernova remnants or relativistic jets, such as those found in AGNs and microquasars. Slow jets have intrinsically different structures in both the generated magnetic fields and the accelerated particle spectrum. In particular, the jet head has a very weak magnetic field and the ambient electrons are strongly accelerated and dragged by the jet particles. The simulation results exhibit jitter radiation from inhomogeneous magnetic fields, generated by the Weibel instability, which has different spectral properties than standard synchrotron emission in a homogeneous magnetic field.

Nishikawa, K.-I.; Hartmann, D. H.; Hardee, P.; Hededal, C.; Mizunno, Y.; Fishman, G. J.

2006-01-01

252

A Newly Recognized Very Young Supernova Remnant in M83  

CERN Document Server

As part of a spectroscopic survey of supernova remnant candidates in M83 using the Gemini-South telescope and GMOS, we have discovered one object whose spectrum shows very broad lines at H$\\alpha$, [O~I] 6300,6363, and [O~III] 4959,5007, similar to those from other objects classified as `late time supernovae.' Although six historical supernovae have been observed in M83 since 1923, none were seen at the location of this object. Hubble Space Telescope Wide Field Camera 3 images show a nearly unresolved emission source, while Chandra and ATCA data reveal a bright X-ray source and nonthermal radio source at the position. Objects in other galaxies showing similar spectra are only decades post-supernova, which raises the possibility that the supernova that created this object occurred during the last century but was missed. Using photometry of nearby stars from the HST data, we suggest the precursor was at least 17 $\\rm M_{sun}$, and the presence of broad H$\\alpha$ in the spectrum makes a type II supernova likely....

Blair, William P; Long, Knox S; Whitmore, Bradley C; Kim, Hwihyun; Soria, Roberto; Kuntz, K D; Plucinsky, Paul P; Dopita, Michael A; Stockdale, Christopher

2015-01-01

253

An Optical Study of the Two Youngest Balmer-dominated Supernova Remnants in the Large Magellanic Cloud  

Science.gov (United States)

Supernova remnants in the Large Magellanic Cloud (LMC) are particularly useful in understanding the properties of high-speed shocks in the interstellar medium. Thanks to their well-known distances (unlike for their Galactic brethren) I can convert angular proper motion measurements of their shock waves, as traced by H? emission, into accurate shock speeds in physical units. Furthermore in some high-speed shocks the H? emission displays a two-component nature consisting of broad and narrow components. The broad line arises from charge exchange of electron from neutral hydrogen that passes through the shock with a post-shock ion. The narrow component comes from collisional excitations of the electrons bound to neutral hydrogen as it passes through the shock. The shock velocity, in conjunction with the H? broad-line width and the broad-to-narrow flux ratio, can be used to test Balmer shock models (Vanadelsberg et al. (2008); see Heng (2010) for a thorough review), assess the level of temperature between post-shock electrons and ions, and search for evidence of efficient cosmic ray acceleration.In this thesis I study two young supernova remnants (SNRs) in the LMC, 0509-67.5 and 0519-69.0, where I measure the shock velocity directly from proper motion measurements using narrow-band H? imaging from the Hubble Space Telescope. I then use optical longslit spectroscopic data obtained from the FORS2 spectrograph (Very Large Telescope) and the Robert Stobie Spectrograph (Southern African Large Telescope). Example results for SNR 0509-67.5 include: a global shock speed of 6,500 km sec-1, an age of 230-390 years, a neutral hydrogen density of 0.84?(?H?/0.2)-1cm-3, and a degree of equilibration (Te,sh/Tion,sh) of less than ~0.03 in the NE of the remnant without the need to invoke CR precursors or efficient cosmic ray acceleration.

Hovey, Luke; Hughes, John Patrick; Eriksen, Kristoffer; McCully, Curtis

2015-01-01

254

Spitzer Observations of Supernova Remnant IC 443  

CERN Document Server

We present Spitzer observations of IC 443 obtained with MIPS and IRS as part of our GTO program on the astrophysics of ejecta from evolved stars. We find that the overall morphology at mid/far IR wavelengths resembles even more closely a loop or a shell than the ground based optical and/or near IR images.The dust temperature map, based on the 70/160micron ratio, shows a range from 18 to 30 K degrees. The IRS spectra confirm the findings from previous near+mid IR spectroscopic observations of a collisionally excited gas, atomic and molecular, rich in fine structure atomic and pure H2 rotational emission lines, respectively. The spectroscopic shock indicator, [Ne II] 12.8micron, suggests shock velocities ranging from 60-90 km/s, consistent with the values derived from other indicators.

Noriega-Crespo, A; Gordon, K; Marleau, F R; Rieke, G H; Rho, J; Latter, W B

2008-01-01

255

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-07-01

256

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 ejectaronounced 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.

257

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

CERN Document Server

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

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

2014-01-01

258

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

259

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

260

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

CERN Document Server

The successful theoretical supernova explosion models should be able to explain any features of the emission from supernovae at any evolutionary stage. We check several models from two different points of view. With the multi-frequency radiation hydro code STELLA we calculate gamma-ray, bolometric and broad-band UBVI light curves. Then we use the same models to calculate the emission from young supernova remnants. Here we present new plots for gamma-ray luminosity from several SN Ia models and recomputations of bolometric and UBVRI light curves of model 13C for SN 1993J.

Sorokina, E; Sorokina, Elena; Blinnikov, Sergey

2003-01-01

 
 
 
 
261

Protrusions Beyond the Blast Waves of Young Type Ia Supernova Remnants: Hydrodynamic Instabilities or Ejecta Bullets?  

Science.gov (United States)

High resolution imaging of two young Type Ia supernova remnants (SNRs), Tycho and SN 1006, has revealed several morphological features which have resisted explanation with numerical simulations. One such feature is the presence of shocked ejecta blobs protruding beyond the mean forward shock radius. Two current theories explain the presence of such ejecta: highly dense ejecta shrapnel produced in the explosion penetrating the forward shock, or plumes generated by hydrodynamic instabilities long after the initial explosion. We investigate the shrapnel theory through hydrodynamic simulations in 2D and 3D of the evolution of dense ejecta clumps embedded in an exponential density profile, appropriate for Type Ia supernovae. We use high-resolution 2D simulations to identify relevant clump parameters which we investigate further in 3D. In contradiction to some former work, we find that sufficiently resolved clumps in 2D models shatter upon collision with the forward shock, yielding new protrusion features. In both 2D and 3D, shrapnel is capable of penetrating the forward shock, but the resultant protrusions in 3D simulations vary significantly from those in similar 2D runs, implying 2D simulations may not be an accurate method of investigating the shrapnel theory. We compare the our simulations with Chandra observations of projections seen in Tycho and SN 1006. 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.

Dyer, Ashton; Blondin, J. M.; Reynolds, S. P.

2014-01-01

262

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

International Nuclear Information System (INIS)

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

263

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

Science.gov (United States)

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

Davidsen, Arthur

1994-01-01

264

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

Energy Technology Data Exchange (ETDEWEB)

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

Burkey, Mary T.; Reynolds, Stephen P.; Borkowski, Kazimierz J.; Blondin, John M., E-mail: reynolds@ncsu.edu [Department of Physics, North Carolina State University, Raleigh NC 27695-8202 (United States)

2013-02-10

265

No cold dust within the supernova remnant Cassiopeia A.  

Science.gov (United States)

A large amount (about three solar masses) of cold (18 K) dust in the prototypical type II supernova remnant Cassiopeia A was recently reported. It was concluded that dust production in type II supernovae can explain how the large quantities (approximately 10(8) solar masses) of dust observed in the most distant quasars could have been produced within only 700 million years after the Big Bang. Foreground clouds of interstellar material, however, complicate the interpretation of the earlier submillimetre observations of Cas A. Here we report far-infrared and molecular line observations that demonstrate that most of the detected submillimetre emission originates from interstellar dust in a molecular cloud complex located in the line of sight between the Earth and Cas A, and is therefore not associated with the remnant. The argument that type II supernovae produce copious amounts of dust is not supported by the case of Cas A, which previously appeared to provide the best evidence for this possibility. PMID:15577902

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

2004-12-01

266

A method for computing synchrotron and inverse-Compton emission from hydrodynamic simulations of supernova remnants  

CERN Document Server

The observational signature of supernova remnants (SNRs) is very complex, in terms of both their geometrical shape and their spectral properties, dominated by non-thermal synchrotron and inverse-Compton scattering. We propose a post-processing method to analyse the broad-band emission of SNRs based on three-dimensional hydrodynamical simulations. From the hydrodynamical data, we estimate the distribution of non-thermal electrons accelerated at the shock wave and follow the subsequent evolution as they lose or gain energy by adiabatic expansion or compression and emit energy by radiation. As a first test case, we use a simulation of a bipolar supernova expanding into a cloudy medium. We find that our method qualitatively reproduces the main observational features of typical SNRs and produces fluxes of the right order of magnitude, allowing for further use in more extended sets of models.

Obergaulinger, M; Aloy, M A; Iyudin, A

2014-01-01

267

SN 1993J - The X-ray Story of a Supernova Slowly Transitioning to a Remnant  

Science.gov (United States)

Supernova 1993J in the nearby galaxy M81 is one of the best observed supernovae (SNe) in X-rays, with better long-term X-ray time-sampling than any other SN. We re-analysed most of the available archival data on SN 1993J, combined with a 79ks Chandra observation obtained by our group in Aug 2010. Together, the data constitute a veritable history of a Type IIb SN from its explosion, through its outward journey into the surrounding medium, and on its way to becoming a remnant. The X-ray emission probes the characteristics of the surrounding medium, and the kinematics of the SN shock wave(s). In this project we explore the evolution of these quantities in SN 1993J, together with the evolution of its X-ray spectrum.

Dwarkadas, V.; Bauer, F.; Bietenholz, M.; Bartel, N.

2014-07-01

268

Two-dimensional magnetohydrodynamics simulations of young Type Ia supernova remnants  

Science.gov (United States)

Using two-dimensional magnetohydrodynamics (MHD) simulations, we investigate the dynamical properties of Type Ia supernova remnants (SNRs) evolved either in a uniform ambient medium or from an interaction with a dense clump. The initial conditions assume that the expansion of the supernova ejecta is of free inertia with a power-law density distribution in the outer part of the ejecta. To include the effects of the diffusive shock acceleration process and the escape of the accelerated particles from the shock front, we use different adiabatic indices in the simulations to study the dynamical evolution of the Type Ia SNRs. Moreover, we investigate the interactions of a SNR with either a small or a large clump. A double-shock structure with a contact discontinuity is produced as the ejecta flow supersonically in the ambient medium; Rayleigh-Taylor instability is clearly shown as fingers near the contact discontinuity in the contour maps of density, and a high density and a high magnetic field can be triggered because of the instability around the Rayleigh-Taylor fingers. We perform simulations with different adiabatic indices, and the results show that a narrower intershock region is produced with a smaller adiabatic index because a larger compression ratio for the SNR shock is induced. The influence of the Rayleigh-Taylor instability on the morphologies of both the forward and reverse shocks is more significant with a smaller adiabatic index. Finally, the simulations of a SNR interacting with a dense clump show that the morphology of the remnant is greatly twisted after the collision, and a filament with a high density and a high magnetic field can be produced as a SNR colliding with a large dense clump.

Fang, Jun; Zhang, Li

2012-08-01

269

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

270

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

CERN Document Server

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

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

1998-01-01

271

The relativistic ISM in M33: Role of the supernova remnants  

Science.gov (United States)

The role of supernova remnants in producing and maintaining the relativistic interstellar medium is investigated for the case of the nearby galaxy M33. Analysis of a radio continuum sample of supernova remnants (SNRs) has led to the following results. (1) The SNRs use roughly 1%-10% of their blast energy to produce relativistic particles. (2) The currently observed SNR population contains between 0.1% and 1% of the relativistic particle energy of the entire interstellar medium of M33, which leads to reasonable values of the particle residence time in the disk. (3) The distribution of synchrotron spectral indices indicates that the particle populations of the observed SNRs have energy spectra with power-law indices of 2.2 +/- 0.4, consistent with values predicted by diffusive shock acceleration theory. Taken together, the three results favor the hypothesis that SNRs account for the bulk of M33's relativistic medium. It is further shown that, as a consequence of these results, the predicted SN rate is 1 per 140-250 yr, in general agreement with independent estimates of the SN rate and the absence of historical supernovae.

Duric, N.; Gordon, S. M.; Goss, W. M.; Viallefond, F.; Lacey, C.

1995-05-01

272

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

Berezhko, E G

2009-01-01

273

Radio maps revealing shell structures in five supernova remnants  

International Nuclear Information System (INIS)

Five southern supernova remnants (SNRs) of small angular diameter (5 - 10 arcmins) have been mapped with the Fleurs synthesis telescope; at the resolution used (better than 1 arcmin) a shell structure can be seen in each remnant. One of the SNRs, G342.0 - 0.2, is a faint source which we confirm as an SNR for the first time. This source and three others, G340.4 + 0.4, G340.6 + 0.3 and G341.9 - 0.3, lie close together on the sky; they have similar distance estimates of approx. 16 kpc and they all may be located in one of the spiral arms on the far side of the Galaxy. The fifth SNR, G352.7 - 0.1, although displaced from the others by more than 10 deg, is at a similar distance and is possibly in the same arm. (author)

274

Supernova remnant evolution in an inhomogeneous medium. I. Numerical models  

International Nuclear Information System (INIS)

We present the first numerical simulations of supernova remnant evolution in an inhomogeneous gas. Evolution in the lowest density substrate (the intercloud) is assumed to be spherically symmetric with a large intercloud filling factor and many dense regions (clouds) within the remnant; however, mass momentum and energy transfer between cloud and intercloud are included and the position and morphology of individual clouds tracked. We consider evolution in several different models of the interstellar medium, both those in which the intercloud gas is diffuse (10-3 to 10-2 cm-3) and those in which it is relatively dense (napprox.0.3 cm-3) under a variety of assumptions about the efficiency of thermal evaporation from the clouds into the intercloud medium

275

High-resolution radio observations of five supernova remnants  

International Nuclear Information System (INIS)

Five supernova remnants have been mapped with high resolution using the Fleurs synthesis radio telescope. Four of the sources (G33.6 + 0.1, G309.2 - 0.6., G315.4 - 0.3 and G320.4 - 1.2) possess shell structures, albeit with considerable distortion; the fifth source, G308.7 + 0.0, has a centrally concentrated brightness distribution reminiscent of the Crab nebula but considerably more elongated. In the general direction of G320.4 - 1.2 there is considerable optical emission but only the brightest features seem to be associated with the radio source; currently available sky survey photographs show no associated optical nebulosity in the direction of the other four remnants. (author)

276

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

277

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

278

Broadband Observations and Modeling of the Shell-Type Supernova Remnant G347.3-0.5  

Science.gov (United States)

The supernova remnant G347.3-0.5 emits a featureless power law in X-rays, thought to indicate shock acceleration of electrons to high energies. We here produce a broadband spectrum of the bright northwest limb of this source by combining radio observations from the Australia Telescope Compact Array (ATCA), X-ray observations from the Advanced Satellite for Cosmology and Astrophysics (ASCA), and TeV gamma-ray observations from the CANGAROO imaging Cerenkov telescope. We assume that this emission is produced by an electron population generated by diffusive shock acceleration at the remnant forward shock. The nonlinear aspects of the particle acceleration force a connection between the widely different wavelength bands and between the electrons and the unseen ions, presumably accelerated simultaneously with the electrons. This allows us to infer the relativistic proton spectrum and estimate ambient parameters such as the supernova explosion energy, magnetic field, matter density in the emission region, and efficiency of the shock acceleration process. We find convincing evidence that the shock acceleration is efficient, placing greater than 25% of the shock kinetic energy flux into relativistic ions. Despite this high efficiency, the maximum electron and proton energies, while depending somewhat on assumptions for the compression of the magnetic field in the shock, are well below the observed 'knee' at 10(exp 15) eV in the Galactic cosmic-ray spectrum.

Ellison, Donald C.; Slane, Patrick O.; Gaensler, Bryan M.

2002-01-01

279

Aspherical Supernova Shock Breakout and the Observations of Supernova 2008D  

CERN Document Server

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

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

2010-01-01

280

Nonthermal X-Ray Emission from the Shell-Type Supernova Remnant G347.3-0.5  

Science.gov (United States)

Recent Advanced Spacecraft for Cosmology Astrophysics (ASCA) observations of G347.3-0.5, a supernova remnant (SNR) discovered in the ROSAT All-Sky Survey, reveal nonthermal emission from a region along the northwestern shell. Here we report on new pointed ASCA observations of G347.3-0.5 that confirm this result for all the bright shell regions and also reveal similar emission, although with slightly different spectral properties, from the remainder of the SNR. Curiously, no thermal X-ray emission is detected anywhere in the remnant. We derive limits on the amount of thermal emitting material present in G347.3-0.5 and present new radio continuum, CO, and infrared results that indicate that the remnant is distant and of moderate age. We show that our observations are broadly consistent with a scenario that has most of the supernova remnant shock wave still within the stellar wind bubble of its progenitor star, while part of it appears to be interacting with denser material. A point source at the center of the remnant has spectral properties similar to those expected for a neutron star and may represent the compact relic of the supernova progenitor.

Slane, Patrick O.; Gaensler, Bryan M.; Dame, T. M.; Hughes, John P.; Plucinsky, Paul P.; Green, Anne

2002-01-01

 
 
 
 
281

Some Recent Progress on the Studies of Supernova Remnants  

CERN Document Server

We briefly reviewed some recent progress on the studies of supernova remnants (SNRs), including the radio SNRs (the structure, polarization, spectrum etc.), observational characteristics of X-ray emission, pulsar wind nebulae (PWNe), association properties between SNR and PSR, interaction of SNR and interstellar medium (ISM), cosmos ray and the SNRs in external galaxies, etc.. Correspondingly to the continue improvement of space and spectrum resolution of the on-ground and in-space astronomical equipments at wavelengthes as radio, optical, X-ray and so on, we know about SNRs more and deeper.

Xu, Jian-Wen

2009-01-01

282

Radio observations of three supernova remnants in M33  

International Nuclear Information System (INIS)

Discrete sources in the southern spiral arm of M33 have been observed with the Westerbork Synthesis Radio Telescope at 49 and 21 cm and the Very Large Array at 6 cm. The three optically confirmed supernova remnants were detected with the WSRT and were found to have non-thermal spectral indices. Two of these SNR were detected with the VLA with a resolution of approximately 1.5 arcsec (5 pc). If it is assumed that these M33 SNR are similar to galactic SNR, the surface-brightness-diameter relationship proposed by Caswell and Lerche indicates a distance of 860 +- 200 kpc for M33. (author)

283

The X-ray Spectrum of Supernova Remnant 1987A  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We discuss the X-ray emission observed from Supernova Remnant 1987A with the Chandra X-ray Observatory. We analyze a high resolution spectrum obtained in 1999 October with the high energy transmission grating (HETG). From this spectrum we measure the strengths and an average profile of the observed X-ray lines. We also analyze a high signal-to-noise ratio CCD spectrum obtained in 2000 December. The good statistics (~ 9250 counts) of this spectrum and the high spatial resolut...

Michael, Eli; Zhekov, Svetozar; Mccray, Richard; Hwang, Una; Burrows, David N.; Park, Sangwook; Garmire, Gordon P.; Holt, Stephen S.; Hasinger, Guenther

2001-01-01

284

A New Evolutionary Phase of Supernova Remnant 1987A  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have been monitoring the supernova remnant (SNR) 1987A with {\\it Chandra} observations since 1999. Here we report on the latest change in the soft X-ray light curve of SNR 1987A. For the last $\\sim$1.5 yr (since day $\\sim$8000), the soft X-ray flux has significantly flattened, staying (within uncertainties) at $f_{\\rm X}$ $\\sim$ 5.7 $\\times$ 10$^{-12}$ erg cm$^{-2}$ s$^{-1}$ (corresponding to $L_{\\rm X}$ $\\sim$ 3.6 $\\times$ 10$^{36}$ erg s$^{-1}$) in the 0.5--2 keV band. ...

Park, Sangwook; Zhekov, Svetozar A.; Burrows, David N.; Racusin, Judith L.; Dewey, Daniel; Mccray, Richard

2011-01-01

285

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)

286

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

287

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

288

High-resolution Studies of Charge Exchange in Supernova Remnants with Magellan, XMM-Newton, and Micro-X  

Science.gov (United States)

Charge exchange, the semi-resonant transfer of an electron from a neutral atom to an excited state in an energetic ion, can occur in plasmas where energetic ions are incident on a cold, at least partially neutral gas. Supernova remnants, especially in the immediate shock region, provide conditions conducive to charge exchange. The emission from post charge-exchange ions as the captured electron cascades down to the ground state, can shed light on the physical conditions of the shock and the immediate post-shock material, providing an important tool to understanding supernova explosions and their aftermath.I present a study of charge exchange in the galactic supernova remnant G296.1-0.5 in two bands: the optical and the X-ray. The optical study, performed using both imaging and spectroscopy from the IMACS instrument on the Magellan Baade Telescope at Las Companas Observatory, seeks to identify `Balmer-dominated shocks' in the remnant, which occur when charge exchange occurs between hot, post-shock protons and colder neutral hydrogen in the environment. The X-ray study probes line ratios in dispersed spectral data obtained with XMM-Newton RGS from an X-ray lobe in the NW of the remnant to hunt for signatures of charge exchange. The dispersed data are degraded by the extended nature of the source, blending many of the lines.We are working towards the future of spectroscopic studies in the X-ray for such extended sources with Micro-X: a sounding rocket-borne, high energy resolution X-ray telescope, utilizing an array of microcalorimeters to achieve high energy resolution for extended sources. I describe the design and commissioning of the payload and the steps toward launch, which is anticipated in the summer of 2015.

Heine, Sarah N.; Figueroa-Feliciano, Enectali; Castro, Daniel

2015-01-01

289

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

290

Spherization of remnants of an asymmetrical supernova explosion in the homogeneous medium  

International Nuclear Information System (INIS)

The spherization of the shock wave is considered, which propagates in the uniform interstellar medium in the presence of the initial asymmetry of the shape and velocity. The calculations have been made in the approximation of 1.5-dimensional hydrodynamics. Three different models have been considered with the preference given to the 'snow-plough'' model. The characteristic time of the spherization is found for different values of the density of the medium and the parameters of the explosion. It is obtained that when the initial asymmetry is large, by the moment of the spherization in the shape of the shock, the large difference of the surface density on the pole and equator remains. This may explain the observed features of the supernova remnant Cas A

291

X-ray observations of supernova remnants from the Einstein Observatory  

International Nuclear Information System (INIS)

The Einstein observatory spacecraft carries an advanced grazingincidence x-ray telescope which is ideal for studying both the spatial and spectral characteristics of supernova remnants. The author reviews some of the important spectral results to data, discusses the x-ray emission process in supernova remnants, and briefly describes the observatory

292

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 regi...

Park, Sangwook; Highes, John P.; Slane, Patrick O.; Mori, Koji; Burrows, David N.

2009-01-01

293

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

International Nuclear Information System (INIS)

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

294

High-velocity, high-excitation neutral carbon in a cloud in the Vela supernova remnant  

Science.gov (United States)

HD 72089 is situated behind the Vela supernova remnant, and the interstellar absorption lines in the spectrum of this star are remarkable for two reasons. First, there are six distinct velocity components that span the (heliocentric) velocity range -60 to +121 km/s in the lines of Na I and Ca II. Second, two of the components at high velocity, one at +85 km/s and another at +121.5 km/s, have densities that are large enough to produce observable lines from neutral carbon. The gas moving at +121.5 km/s has such a large pressure that the excited fine-structure levels of the ground electronic state of C I are collisionally populated nearly in proportion to their level degeneracies. This high-velocity gas exhibits unusually low column densities of Mg I and Na I, compared to that of C I. We propose that the +121.5 km/s component represents gas that has cooled and recombined in a zone that follows a shock driven into a cloud by the very recent passage of a supernova blast wave. A representative preshock density of n(sub H) approximately = 13/cc and velocity v(sub s) = 100 km/s is indicated by the strength of diffuse (O III) emission lines seen in directions very near HD 72089. The strong collisional population of excited C I and apparent absence of excited levels of O I give a most favorable fit to the conditions 1000 less than n(sub H) less than 2900/cc over a temperature range 300 less than T less than 1000 K. The fact that the compression is not substantially more than this indicates that the preshock gas may have had an embedded, transverse magnetic field with a strength B greater than or approximately = 1 micro-G. The large dynamical pressure of the supernova blast wave that would be needed to create the cloud shock that we describe implies that the energy of the supernova was 8 x 10(exp 51) ergs, if the Vela remnant is 500 pc away. We can bring this value much closer to typical supernova energies E less than or approximately = 10(exp 51) ergs if the distance to the remnant is revised downward by at least a factor of 2.

Jenkins, Edward B.; Wallerstein, George

1995-01-01

295

HESS J1818-154, a new composite supernova remnant discovered in TeV gamma rays and X-rays  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Composite supernova remnants (SNRs) constitute a small subclass of the remnants of massive stellar explosions where non-thermal radiation is observed from both the expanding shell-like shock front and from a pulsar wind nebula (PWN) located inside of the SNR. These systems represent a unique evolutionary phase of SNRs where observations in the radio, X-ray, and $\\gamma$-ray regimes allow the study of the co-evolution of both these energetic phenomena. In this article, we rep...

Collaboration, H. E. S. S.; Abramowski, A.; Aharonian, F.; Benkhali, F. Ait; Akhperjanian, A. G.; Angu?ner, E.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Tjus, J. Becker; Bernlo?hr, K.; Birsin, E.; Bissaldi, E.

2013-01-01

296

The Unusual Young Supernova Remnant Population in M83  

Science.gov (United States)

The face-on grand design spiral galaxy M83 (d=4.6 Mpc) is a veritable supernova factory, having generated six known SNe in less than 100 years. Hence, one might expect of order 60 or more supernova remnants (SNRs) less than a thousand years old that might shed light on the poorly understood ejecta-dominated phase of early SNR evolution, as well as many more older, ISM-dominated remnants that should still be visible. We are conducting a multi-wavelength Chandra/Hubble/ground-based campaign to find and characterize the SNRs in M83, concentrating especially on the younger population. HST/WFC3 emission-line data for seven fields covering the bulk of the bright optical disk have allowed us to identify ~50 optical SNR candidates with angular sizes below 0.5” (super-solar metal abundances in much of this galaxy. We will show representative data from all relevant data sets that lead us to this conclusion. This work is supported in part by STScI grant HST-GO-12513.01-A and Chandra grant SAO-GO1-12115C to Johns Hopkins University.

Blair, William P.; Dopita, M. A.; Ghavamian, P.; Kuntz, K. D.; Long, K. S.; Plucinsky, P. P.; Soria, R.; Winkler, P. F.

2014-01-01

297

Dust Formation Observed in Young Supernova Remnants with Spitzer  

CERN Document Server

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

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

2009-01-01

298

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

299

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

300

DENSE IRON EJECTA AND CORE-COLLAPSE SUPERNOVA EXPLOSION IN THE YOUNG SUPERNOVA REMNANT G11.2-0.3  

International Nuclear Information System (INIS)

We present the results of near-infrared spectroscopic observations of dense (?>103 cm-3) iron ejecta in the young core-collapse supernova remnant G11.2-0.3. Five ejecta knots projected to be close to its center show a large dispersion in their Doppler shifts: two knots in the east are blueshifted by more than 1000 km s-1, while three western knots have relatively small blueshifts of 20-60 km s-1. This velocity discrepancy may indicate that the western knots have been significantly decelerated or that there exists a systematic velocity difference among the knots. One ejecta filament in the northwestern boundary, on the other hand, is redshifted by ?>200 km s-1, while opposite filament in the southeastern boundary shows a negligible radial motion. Some of the knots and filaments have secondary velocity components, and one knot shows a bow shock-like feature in the velocity structure. The iron ejecta appear to be devoid of strong emission from other heavy elements, such as S, which may attest to the ?-rich freezeout process in the explosive nucleosynthesis of the core-collapse supernova explosion close to its center. The prominent bipolar distribution of the Fe ejecta in the northwestern and southeastern direction, along with the elongation of the central pulsar wind nebula in the perpendicular direction, is consistent with the interpretation that the supernova exploded primarily along the northwestern and southrily along the northwestern and southeastern direction.

 
 
 
 
301

THE MIPSGAL VIEW OF SUPERNOVA REMNANTS IN THE GALACTIC PLANE  

International Nuclear Information System (INIS)

We report the detection of Galactic supernova remnants (SNRs) in the mid-infrared (at 24 and 70 ?m), in the coordinate ranges 100 0 and 2850 0, |b| 0, using 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 a ratio of 70 ?m to 1.4 GHz which is similar to those found in previous studies of SNRs (with the exception of a few that have ratios closer to those of H II regions). Furthermore, we retrieve a slope close to unity when correlating infrared (24 and 70 ?m) with 1.4 GHz emission. Our survey is more successful in detecting remnants with bright X-ray emission, which we find is well correlated with the 24 ?m morphology. Moreover, by comparing the power emitted in the X-ray, infrared, and radio, we conclude that the energy released in the infrared is comparable to the cooling in the X-ray range.

302

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

303

The Extraordinary Supernova Remnant in NGC 4449 Revisited  

Science.gov (United States)

NGC 4449, a Magellanic-type irregular galaxy at a distance of about 4 Mpc, contains the most luminous known supernova remnant (SNR) in both X-ray and optical bands. Its optical spectrum is characterized by broad lines from O, Ne, S, Ar, and Ca, and its size and expansion velocity (6000 km/s) suggest that the unobserved SN exploded about 65 years ago. The remnant¹s extraordinary brightness can be attributed to the interaction of supernova ejecta with unusually dense and extensive circumstellar material. We will present new Chandra imaging, together with UV/Optical spectra of the SNR from HST/STIS and the MMT. The X-ray luminosity of the SNR is less than when it was detected with Einstein in 1980, but the luminosity and X-ray spectral shape have remained relatively constant over the last 10 years. In the FUV, the HST spectra show for the first time broad line emission from C IV 1550 Å, as well as Si IV + O IV at 1400 Å and O III] at 1660 Å. The new NUV and optical spectra are fairly similar to earlier HST/FOS spectra and to ground-based spectra we have obtained over the last decade. Here we describe these new observations, and our attempts to understand the nature of the progenitor of the SNR.We acknowledge support for this effort from NASA through grant GO-12462 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc, under NASA contract NAS5-26555, and through Chandra Award Number GO9-0075, issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory, under NASA contract NAS8-03060.

Long, Knox S.; Blair, William P.; Fesen, Robert A.; Milisavljevic, Dan; Winkler, P. Frank

2015-01-01

304

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

305

The contribution of supernova remnants to the galactic cosmic ray spectrum  

CERN Document Server

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

Caprioli, D; Blasi, P

2009-01-01

306

Iron-Rich Ejecta in the Supernova Remnant DEM L71  

CERN Document Server

Chandra X-ray observations of DEM L71, a supernova remnant (SNR) in the Large Magellanic Cloud (LMC), reveal a clear double shock morphology consisting of an outer blast wave shock surrounding a central bright region of reverse-shock heated ejecta. The abundances of the outer shock are consistent with LMC values, while the ejecta region shows enhanced abundances of Si, Fe, and other species. However, oxygen is not enhanced in the ejecta; the Fe/O abundance ratio there is more than 5 times the solar ratio. Based on the relative positions of the blast wave shock and the contact discontinuity in the context of SNR evolutionary models, we determine a total ejecta mass of approximately 1.5 solar masses. Ejecta mass estimates based on emission measures derived from spectral fits are subject to considerable uncertainty due to lack of knowledge of the true contribution of hydrogen continuum emission. Maximal mass estimates, i.e., assuming no hydrogen, result in 1.5 solar masses of Fe and 0.24 solar masses of Si. Unde...

Hughes, J P; Rakowski, C E; Slane, P O; Hughes, John P.; Ghavamian, Parviz; Rakowski, Cara E.; Slane, Patrick O.

2003-01-01

307

The Evolution of Supernova Remnants in the Early Universe  

Science.gov (United States)

We investigate the evolution of supernova remnants (SNRs) in the early universe by solving the one-dimensional hydrodynamics and non-equilibrium chemistry under spherical symmetry. A cooled dense shell, which is formed behind the supernova blastwave during snowplow phase, is thought to be an important site where star formation activity occurs after shell fragmentation. To evaluate the characteristic fragmentation mass of the shell, we calculate the thermal and chemical evolution of the shell. We show that the gas within the shell cools by H2 or HD line cooling in the metal-free or extremely low-metallicity environments (=10-3 Zsolar). We then study the shell fragmentation using the linear stability analysis of an expanding shell. Since the gas mass which can cool by HD or metal line cooling is very low, shell fragmentation is unlikely to occur unless the ambient temperature is very low (100 K). The shell fragmentation thus strongly depends on the densities and temperatures of the ambient medium and the supernova energy but depends weakly on the metallicity.

Nagakura, Takanori; Hosokawa, Takashi; Omukai, Kazuyuki

2008-03-01

308

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

309

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

310

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

311

Supernova Shock Breakout Through a Wind  

CERN Document Server

The breakout of a supernova shock wave through the progenitor star's outer envelope is expected to appear as an X-ray flash. However, if the supernova explodes inside an optically-thick wind, the breakout flash is delayed. We present a simple model for estimating the conditions at shock breakout in a wind based on the general observable quantities in the X-ray flash lightcurve: the total energy E_X, and the diffusion time after the peak, t_diff. We base the derivation on the self-similar solution for the forward-reverse shock structure expected for an ejecta plowing through a pre-existing wind at large distances from the progenitor's surface. We find simple quantitative relations for the shock radius and velocity at breakout. By relating the ejecta density profile to the pre-explosion structure of the progenitor, the model can also be extended to constrain the combination of explosion energy and ejecta mass. For the observed case of XRO08109/SN2008D, our model provides reasonable constraints on the breakout r...

Balberg, Shmuel

2011-01-01

312

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

Energy Technology Data Exchange (ETDEWEB)

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

Abdo, A.A.

2011-08-19

313

Fermi LAT gamma-ray observations of the supernova remnant HB21  

CERN Document Server

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

Pivato, G; Tibaldo, L

2013-01-01

314

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

International Nuclear Information System (INIS)

We report the discovery of thermal X-ray emission from the youngest Galactic supernova remnant G1.9+0.3, from a 237 ks Chandra observation. We detect strong K? lines of Si, S, Ar, Ca, and Fe. In addition, we detect a 4.1 keV line with 99.971% confidence which we attribute to 44Sc, produced by electron capture from 44Ti. Combining the data with our earlier Chandra observation allows us to detect the line in two regions independently. For a remnant age of 100 yr, our measured total line strength indicates synthesis of (1-7) x 10-5 M sun of 44Ti, in the range predicted for both Type Ia and core-collapse supernovae (SNe), but somewhat smaller than the 2 x 10-4 M sun reported for Cas A. The line spectrum indicates supersolar abundances. The Fe emission has a width of about 28,000 km s-1, consistent with an age of ?100 yr and with the inferred mean shock velocity of 14,000 km s-1 deduced assuming a distance of 8.5 kpc. Most thermal emission comes from regions of lower X-ray but higher radio surface brightness. Deeper observations should allow more detailed spatial mapping of 44Sc, with significant implications for models of nucleosynthesis in Type Ia SNe.

315

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

316

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

CERN Document Server

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

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

2010-01-01

317

An Investigation into PAH Destruction in Nearby Supernova Remnants, North Polar Spur and Cygnus Loop  

Science.gov (United States)

Our goal in conducting this research was to look at the polycyclic aromatic hydrocarbon (PAH)/large dust grain emission intensity ratio in nearby supernova remnants to find evidence for selective PAH destruction by hot gas and high velocity shock waves within these regions, as predicted by the models of Arendt et al. (2010) and Micelotta et al. (2010a,b). Two supernova remnants were studied- the North Polar Spur (NPS) and the Cygnus Loop. The data for PAHs were obtained from the WISE W3 12 micron all-sky map processed by Meisner & Finkbeiner (2014), and the data for the larger grains come from the IRAS 100 micron all-sky map processed by Schlegel, Finkbeiner & Davis (1998). After obtaining a control PAH/large grain intensity ratio of ~2.8 (DN/px)/(MJy/sr) from two high latitude clouds, MBM 30 and MBM 32, we found that the intensity ratios across the NPS and Cygnus Loop were not far off- ~2.7 (DN/px)/(MJy/sr) and ~3.1 (DN/px)/(MJy/sr), respectively- showing no evidence of selective large-scale PAH destruction in supernova remnants. The individual intensities for both PAHs and large grains do decrease inside the Cygnus Loop, however, suggesting a decrease in abundances of both grain types, which could mean total dust grain destruction with the normal ratios coming from foreground and background dust located in the line of sight of the remnant. In addition, temperature and E(B-V) measurements taken from calibrated IRAS images show that while the dust column density increases in the Eastern Veil of the Cygnus Loop, the dust temperature reaches a local maximum, indicating the heating of large grains by interaction with the hot gas in the remnant. The PAH/large grain ratio in the Eastern Veil does decrease and could be indicative of currently ongoing active grain destruction there, with the PAHs being destroyed on a more rapid timescale than the large grains.We are grateful for financial support from the NSF REU Program grant to the Department of Physics & Astronomy at the University of Toledo.

Burkhart, Sarah M.; Witt, Adolf N.

2015-01-01

318

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

319

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

320

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

CERN Document Server

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

Wang, Wei

2014-01-01

 
 
 
 
321

Hard X-Ray Emission and 44Ti Line Features of the Tycho Supernova Remnant  

Science.gov (United States)

A deep hard X-ray survey of the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has detected for the first time non-thermal emission up to 90 keV in the Tycho supernova (SN) remnant. Its 3-100 keV spectrum is fitted with a thermal bremsstrahlung of kT ~ 0.81 ± 0.45 keV plus a power-law model of ? ~ 3.01 ± 0.16. Based on diffusive shock acceleration theory, this non-thermal emission, together with radio measurements, implies that the Tycho remnant may not accelerate protons up to >PeV but to hundreds TeV. Only heavier nuclei may be accelerated to the cosmic ray spectral "knee." In addition, using INTEGRAL, we search for soft gamma-ray lines at 67.9 and 78.4 keV that come from the decay of radioactive 44Ti in the Tycho remnant. A bump feature in the 60-90 keV energy band, potentially associated with the 44Ti line emission, is found with a marginal significance level of ~2.6?. The corresponding 3? upper limit on the 44Ti line flux amounts to 1.5 × 10-5 photon cm-2 s-1. Implications on the progenitor of the Tycho SN, considered to be a Type Ia SN prototype, are discussed.

Wang, Wei; Li, Zhuo

2014-07-01

322

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

323

Origin of Galactic Cosmic Rays from Supernova Remnants  

CERN Document Server

We analyze the results of recent measurements of Galactic cosmic ray (GCRs) energy spectra and the spectra of nonthermal emission from supernova remnants (SNRs) in order to determine their consistency with GCR origin in SNRs. It is shown that the measured primary and secondary CR nuclei energy spectra as well as the observed positron-to-electron ratio are consistent with the origin of GCRs up to the energy 10^17 eV in SNRs. Existing SNR emission data provide evidences for efficient CR production in SNRs accompanied by significant magnetic field amplification. In some cases the nature of the detected gamma-ray emission is difficult to determine because key SNR parameters are not known or poorly constrained.

Berezhko, E G

2014-01-01

324

Investigations of supernovae and supernova remnants in the era of SKA  

CERN Document Server

Two main physical mechanisms are used to explain supernova explosions: thermonuclear explosion of a white dwarf(Type Ia) and core collapse of a massive star (Type II and Type Ib/Ic). Type Ia supernovae serve as distance indicators that led to the discovery of the accelerating expansion of the Universe. The exact nature of their progenitor systems however remain unclear. Radio emission from the interaction between the explosion shock front and its surrounding CSM or ISM provides an important probe into the progenitor star's last evolutionary stage. No radio emission has yet been detected from Type Ia supernovae by current telescopes. The SKA will hopefully detect radio emission from Type Ia supernovae due to its much better sensitivity and resolution. There is a 'supernovae rate problem' for the core collapse supernovae because the optically dim ones are missed due to being intrinsically faint and/or due to dust obscuration. A number of dust-enshrouded optically hidden supernovae should be discovered via SKA1-...

Wang, Lingzhi; Zhu, Hui; Tian, Wenwu; Wang, Xiaofeng

2015-01-01

325

Gamma-ray emission from young supernova remnants: hadronic or leptonic?  

CERN Document Server

The debate on the nature of the gamma-ray emission from young supernova remnants is still open. Ascribing such emission to hadronic rather than leptonic processes would provide an evidence for the acceleration of protons and nuclei, and this fact would fit with the very popular (but not proven) paradigm that supernova remnants are the sources of Galactic cosmic rays. Here, we discuss this issue with a particular focus on the best studied gamma-ray-bright supernova remnant: RX~J1713.7-3946.

Gabici, S

2015-01-01

326

Excitation and Disruption of a Giant Molecular Cloud by the Supernova Remnant 3C 391  

CERN Document Server

Using the IRAM 30-m telescope, we observed the supernova remnant 3C391 (G31.9+0.0) and its surroundings in the CO(2-1), HCO+(1-0), CS(2-1), CS(3-2), and CS(5-4) lines. The ambient molecular gas at the distance of the remnant comprises a giant molecular cloud whose edge is closely parallel to a ridge of bright non-thermal radio continuum, which evidently delineates the blast-wave into the cloud. We found that in a small (0.6 pc) portion of the radio shell, the molecular line profiles consist of a narrow (2 km/s) component, plus a very wide (> 20 km/s) component. Both spectral components peak within 20" of a previously-detected OH 1720 MHz maser. We name this source 3C391:cs; it provides a new laboratory, similar to IC 443 but on a larger scale, to study shock interactions with dense molecular gas. The wide spectral component is relatively brighter in the higher-excitation lines. We interpret the wide spectral component as post-shock gas, either smoothly accelerated or partially dissociated and reformed behind ...

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

1999-01-01

327

Supernova Remnant 1987A: Opening the Future by Reaching the Past  

CERN Document Server

We report an up-turn in the soft X-ray light curve of supernova remnant (SNR) 1987A in late 2003 (~6200 days after the explosion), as observed with the Chandra X-ray Observatory. Since early 2004, the rapid increase of the 0.5-2 keV band X-ray light curve can no longer be described by the exponential density distribution model with which we successfully fitted the data between 1990 and 2003. Around day ~6200, we also find that the fractional contribution to the observed soft X-ray flux from the decelerated shock begins to exceed that of the fast shock and that the X-ray brightening becomes "global" rather than "spotty". We interpret these results as evidence that the blast wave has reached the main body of the dense circumstellar material all around the inner ring. This interpretation is supported by other recent observations, including a deceleration of the radial expansion of the X-ray remnant, a significant up-turn in the mid-IR intensities, and the prevalence of the optical hot spots around the entire inn...

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

2005-01-01

328

Abundance gradients in M31: Comparison of results from supernova remnants and H II regions  

International Nuclear Information System (INIS)

We have obtained spectra of 11 H II regions and additional spectra of six previously reported supernova remnants (SNRs) in M31. The SNR spectra have been used in conjunction with shock model calculations to give abundances of oxygen, nitrogen, and sulfur in the interstellar gas comprising each remnant. We have also determined abundances for the H II regions using the empirical method described by Pagel et al. Both nitrogen and oxygen abundances decrease by about a factor of 4 from the innermost regions studied (approx.4 kpc) to the outer regions (approx.23 kpc). These gradients are similar to those found in other intermediate and late type spiral galaxies, including our own. The mean nitrogen and sulfur abundances are similar to those of the Orion Nebula, but the mean oxygen abundance is about a factor of 2 higher, accounting for the low excitation of the M31 h II regions. A comparison of the SNR and H II region abundance gradients shows substantial agreement for nitrogen, but discordant results for oxygen; this may be due to problems with the shock models since they do not reproduce the observed relative line intensities of O0, O+, and O++. Finally we present observations of SNR candidates in NGC 2403 and IC 342 and discuss the limitations and accuracy of the methods of detecting extragalactic SNRs

329

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2010-01-01

330

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

331

Searches for continuous gravitational waves from nine young supernova remnants  

CERN Document Server

We describe directed searches for continuous gravitational waves in data from the sixth LIGO science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of ten. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3-25.3 days using the matched-filtering F-statistic. We found no credible gravitational-wave signals. We set 95% confidence upper limits as strong (low) as $4\\times10^{-25}$ on intrinsic strain, $2\\times10^{-7}$ on fiducial ellipticity, and $4\\times10^{-5}$ on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.

Aasi, J; Abbott, R; Abbott, T; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Adams, T; Addesso, P; Adhikari, R X; Adya, V; Affeldt, C; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Ain, A; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J S; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Aylott, B E; Babak, S; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barclay, S; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Bartlett, J; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauer, Th S; Baune, C; Bavigadda, V; Behnke, B; Bejger, M; Belczynski, C; Bell, A S; Bell, C; Benacquista, M; Bergman, J; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Biwer, C; Bizouard, M A; Blackburn, J K; Blackburn, L; Blair, C D; Blair, D; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bojtos, P; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brown, N M; Buchman, S; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Bustillo, J Calderón; Calloni, E; Camp, J B; Cannon, K C; Cao, J; Capano, C D; Carbognani, F; Caride, S; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio,, M; Conte, A; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J -P; Countryman, S; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Creighton, T D; Cripe, J; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Cutler, C; Dahl, K; Canton, T Dal; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dartez, L; Dattilo, V; Dave, I; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; DeBra, D; Debreczeni, G; Degallaix, J; De Laurentis, M; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Dojcinoski, G; Dolique, V; Dominguez, E; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Edwards, M; Effler, A; Eggenstein, H -B; Ehrens, P; Eichholz, J; Eikenberry, S S; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fays, M; Fehrmann, H; Fejer, M M; Feldbaum, D; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Fiori, I; Fisher, R P; Flaminio, R; Fournier, J -D; Franco, S; Frasca, S; Frasconi, F; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fuentes-Tapia, S; Fulda, P; Fyffe, M; Gair, J R; Gammaitoni, L; Gaonkar, S; Garufi, F; Gatto, A; Gehrels, N; Gemme, G; Gendre, B; Genin, E; Gennai, A; Gergely, L Á; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Gräf, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Groot, P; Grote, H; Grunewald, S; Guidi, G M; Guido, C J; Guo, X; Gushwa, K; Gustafson, E K; Gustafson, R; Hacker, J; Hall, E D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M; Hartman, M T; Haster, C -J; Haughian, K; Hee, S; Heidmann, A; Heintze, M; Heinzel, G; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Hollitt, S E; Holt, K; Hopkins, P; Hosken, D J; Hough, J; Houston, E; Howell, E J; Hu, Y M; Huerta, E; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Idrisy, A; Indik, N; Ingram, D R; Inta, R; Islas, G; Isler, J C; Isogai, T; Iyer, B R; Izumi, K; Jacobson, M; Jang, H; Jaranowski, P; Jawahar, S; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Keppel, D G; Key, J S

2014-01-01

332

FERMI LARGE AREA TELESCOPE OBSERVATION OF SUPERNOVA REMNANT S147  

International Nuclear Information System (INIS)

We present an analysis of gamma-ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope in the region around supernova remnant (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? confidence level. The gamma-ray flux is (3.8 ± 0.6) × 10–8 photons cm–2 s–1, corresponding to a luminosity of 1.3 × 1034 (d/1.3 kpc)2 erg s–1 in this energy range. The gamma-ray emission exhibits a possible spatial correlation with the prominent H? filaments of SNR 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 ? mesons produced through the proton-proton collisions in the filaments. The reacceleration of the pre-existing cosmic rays and subsequent adiabatic compression in the filaments is sufficient to provide the energy density required of high-energy protons.

333

Imaging of the Supernova Remnant Cassiopeia A with the Multiband Imaging Photometer for Spitzer (MIPS)  

Science.gov (United States)

We present new images of the supernova remnant (SNR) Cas A observed in the 24 and 70 ?m bands of the Spitzer Space Telescope (Spitzer). The IR emission correlates well with the Si X-ray and optical [S II] emission but poorly with either the synchrotron-dominated radio structure or the continuum X-ray emission. The IR is therefore dominated by thermal emission from dust within the SNR and associated with emission-line gas inside the reverse shock region, confirming earlier IRAS and Infrared Space Observatory results. Supplemented by new photometric measurements from archived Midcourse Space Experiment images, we suggest stochastic heating to model the overall mid- to far-IR spectral energy distribution. The 24 and 70 ?m images also reveal a counterjet to the well-known northeast jet feature imaged previously at X-ray, optical, and radio wavelengths. This IR counterjet corresponds well with (optical) fast-moving knots confirming its outflow nature. The opposing jetlike features define a symmetry axis that bisects the SNR and suggest that the supernova explosion was axisymmetric. The IR images also show a region in which the SNR forward shock appears to be propagating into a ~650 Msolar molecular cloud. The new images also show other details of the surrounding ISM structure, including two groups of knots extending ~6'-12' on either side of the SNR.

Hines, D. C.; Rieke, G. H.; Gordon, K. D.; Rho, J.; Misselt, K. A.; Woodward, C. E.; Werner, M. W.; Krause, O.; Latter, W. B.; Engelbracht, C. W.; Egami, E.; Kelly, D. M.; Muzerolle, J.; Stansberry, J. A.; Su, K. Y. L.; Morrison, J. E.; Young, E. T.; Noriega-Crespo, A.; Padgett, D. L.; Gehrz, R. D.; Polomski, E.; Beeman, J. W.; Haller, E. E.

2004-09-01

334

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

335

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

CERN Document Server

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

Fatuzzo, M; Melia, F

2006-01-01

336

Radio Emission from a Young Supernova Remnant Interacting with an Interstellar Cloud Magnetohydrodynamic Simulation with Relativistic Electrons  

CERN Document Server

We present two-dimensional MHD simulations of the evolution of a young Type Ia supernova remnant during its interaction with an interstellar cloud of comparable size at impact. We include for the first time in such simulations explicit relativistic electron transport, including spectral information using a simple but effective scheme that follows their acceleration at shocks and subsequent transport. From this information we also model radio synchrotron emission, including spectra. The principal conclusions from these experiments are: 1) Independent of the cloud interaction, the SNR reverse shock can be an efficient site for particle acceleration in a young SNR. 2) At these early times the synchrotron spectral index due to electrons accelerated at the primary shocks should be close to 0.5 unless those shocks are modified by cosmic-ray pressures. However, interaction with the cloud generates regions of distinctly steeper spectra, which may complicate interpretation in terms of global dynamical models for SNR e...

Jun, B I; Jun, Byung-Il

1999-01-01

337

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

International Nuclear Information System (INIS)

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

338

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

339

A Multiwavelength Study of Supernova Remnants in M33: The Radio Subsample  

Science.gov (United States)

M33 is the current focus of a project to identify and study supernova remnantsi (SNRs) using observations in radio, X-ray and optical wavelengths. Here, we present the results from the radio selected sample of SNRs in M33. The radio observations were obtained with the Very Large Array and the Westerbork Synthesis Array at 6 and 20 cm. The flux and spectral index of all sources down to the 3sigma noise level of the maps have been measured. From the resulting catalogue, a list of candidate SNRs has been compiled, where the sample is defined as all radio sources with a non-thermal spectral index. This effectively eliminates most HII regions, but also includes background radio sources. Because of the inclusion of background sources, it is necessary to turn to other wavelengths for confirmation. We have examined the sites of radio emission using interference filter (6100 Angstroms, [SII], H? ) observations taken with the KPNO 4m telescope. Following the method of Long et al. (1990,Ap. J. Suppl. 72,61), we have identified a list of 37 non-thermal radio sources that have a high [SII]/H? ratio, making them probable optical SNR candidates. We have observed 32 of these spectroscopically at the MMT with the Red Channel long-slit spectrograph. The results of these observations will be presented. The multiwavelength approach allows us more than the ability to confirm the existence of new remnants, it also gives us valuable information on the dynamics of the SNR and its interaction with the surrounding medium. As an example, we are studying a particularily interesting remnant in M33 which has been detected in X-ray, radio and optical and is located in the HII region NGC 592. With information from all three wavelengths we are exploring the properties of the shock, the efficiency of conversion of shock energy into relativistic particles, and the state of evolution of the remnant.

Gordon, S.; Kirshner, R.; Duric, N.; Long, K.

1992-12-01

340

0049-73.6: A Remnant of a Low-Mass Core-Collapse Supernova  

Science.gov (United States)

We present observations with the Chandra X-Ray Observatory of the supernova remnant 0049-73.6 in the Small Magellanic Cloud (SMC). In addition to the outer shell of the swept-up SMC gas, a bright ejecta dominated-ring is present in the remnant's interior. X-ray spectrum of the outer shell shows normal SMC abundances, and allows us to estimate the current blast wave speed at 600 km s-1. The swept-up mass is equal to 160 M?, the SNR age is 16,000 yr, and the explosion energy is 8 × 1050 ergs. The brightest parts of the inner ring are dominated by O- and Ne-rich heavy-element ejecta. 0049-73.6 is thus a remnant of a core-collapse explosion. More diffuse interior ejecta emission shows less prominent O and Ne lines. We performed 1-D hydrodynamical simulations in order to understand the spatial structure of 0049-73.6. We identify the bright inner ring with a dense shell of ejecta interior to the contact discontinuity separating the shocked SMC gas and the SN ejecta. The reverse shock itself might might have already propagated into the low-density innermost ejecta. The observed location of the bright ring allows us to set up an upper limit of about 7-8 M? of SN ejecta. The total mass of O within heavy-element ejecta is about 0.2--0.3 M?. The filling fraction of the O-rich gas is less than 1%, and its high ionization state suggests that the observed emission is dominated by the dense ejecta clumps. The progenitor mass is estimated at about 10 M?. It is likely that the progenitor star was a red supergiant star such as seen in a recent Type II-plateau SN 2003gd.

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

2004-08-01

 
 
 
 
341

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

CERN Document Server

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

Arbutina, Bojan

2012-01-01

342

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

343

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

344

Radio Emission from Young Supernovae and Supernova Remnants in Arp 299  

CERN Document Server

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 Cas 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 p...

Ulvestad, James S

2009-01-01

345

The Crab Nebula and related supernova remnants; Proceedings of the Workshop, George Mason University, Fairfax, VA, October 11, 12, 1984  

Science.gov (United States)

Papers are presented on the Crab Nebula's composition, helium distribution, outer structure and jet, and evolution. Attention is given to line emission from supernova remnants and charge transfer reactions, a magnetohydrodynamic model of the Crab Nebula and its radiation, inferences made using data on the pulsed flux from the crab pulsar, a new interpretation of the crab pulsar X-ray interpulse radiation, and evolutionary models of the Crab Nebula's progenitor. Other topics include the evolution of the centimeter flux of 3C58 and the Crab Nebula, a search for a shock wave around the Crab Nebula, high resolution radio studies of the Crab Nebula, supernova shell structure, and the nature of the remnant 0540-693 and its implications for the study of crablike remnants. Papers are also presented on X-ray observations of: Crab-like remnants, the Crab Nebula, the Vela X region, W28, and 3C400.2. Other papers include the 50 millisecond pulsar in the Large Magellanic Cloud and the X-ray pulse emission mechanism, optical emission from the plerionic core of CTB 80, and one-arcminute resolution observations of W50.

Kafatos, M. C.; Henry, R. B. C.

346

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

347

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

CERN Document Server

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

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

2013-01-01

348

Chandra observation of the Galactic supernova remnant CTB 109 (G109.1-1.0)  

CERN Document Server

Context: We study the X-ray emission of the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0), which is well-known for its enigmatic half-shell morphology both in radio and in X-rays and is associated with the anomalous X-ray pulsar (AXP) 1E2259+586. Aims: We want to understand the origin of the X-ray bright feature inside the SNR called the Lobe and the details of the interaction of the SNR shock wave with the ambient interstellar medium (ISM). Methods: The Lobe and the northeastern part of the SNR were observed with Chandra ACIS-I. We analysed the spectrum of the X-ray emission by dividing the entire observed emission into small regions. The X-ray emission is best reproduced with one-component or two-component non-equilibrium ionisation models depending on the position. In the two-component model one emission component represents the shocked ISM and the other the shocked ejecta. Results: We detect enhanced element abundances, in particular for Si and Fe, in and around the Lobe. There is one particular r...

Sasaki, Manami; Gaetz, Terrance J; Bocchino, Fabrizio

2013-01-01

349

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

350

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

Science.gov (United States)

We have developed an inversion method for determination of the characteristics of the acceleration mechanism directly and nonparametrically from observations, in contrast to the usual forward fitting of parametric model variables to observations. In two recent papers [V. Petrosian and Q. Chen, Astrophys. J. 712, L131 (2010); Q. Chen and V. Petrosian, Astrophys. J. 777, 33 (2013)], we demonstrated the efficacy of this inversion method by its application to acceleration of electrons in solar flares based on stochastic acceleration by turbulence. Here we explore its application for determining the characteristics of shock acceleration in supernova remnants (SNRs) based on the electron spectra deduced from the observed nonthermal radiation from SNRs and the spectrum of the cosmic ray electrons observed near the Earth. These spectra are related by the process of escape of the electrons from SNRs and energy loss during their transport in the Galaxy. Thus, these observations allow us to determine spectral characteristics of the momentum and pitch angle diffusion coefficients, which play crucial roles in both direct acceleration by turbulence and in high Mach number shocks. Assuming that the average electron spectrum deduced from a few well-known SNRs is representative of those in the solar neighborhood, we find interesting discrepancies between our deduced forms for these coefficients and those expected from well-known wave-particle interactions. This may indicate that the standard assumptions made in the treatment of shock acceleration need revision. In particular, the escape of particles from SNRs may be more complex than generally assumed.

Petrosian, Vahé; Chen, Qingrong

2014-05-01

351

SPECTRA OF COSMIC-RAY PROTONS AND HELIUM PRODUCED IN SUPERNOVA REMNANTS  

Energy Technology Data Exchange (ETDEWEB)

Data obtained in the Advanced Thin Ionization Calorimeter (ATIC-2), Cosmic Ray Energetics and Mass (CREAM), and Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) experiments suggest that the elemental interstellar spectra of cosmic rays below the knee at a few times 10{sup 6} GeV are not simple power laws, but that they experience hardening at a magnetic rigidity of about 240 GV. Another essential feature is the difference between proton and helium energy spectra, such that the He/p ratio increases by more than 50% in the energy range from 10{sup 2} to 10{sup 4} GV. We consider the concavity of the particle spectrum resulting from the nonlinear nature of diffusive shock acceleration in supernova remnants (SNRs) as a possible reason for the observed spectrum hardening. The increase of the helium-to-proton ratio 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 the produced overall cosmic-ray spectrum more pronounced. The spectra of protons and helium nuclei accelerated in SNRs and released into the interstellar medium are calculated. The derived steady-state interstellar spectra are in reasonably good agreement with observations.

Ptuskin, Vladimir; Zirakashvili, Vladimir [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Science (IZMIRAN), Troitsk, Moscow Region 142190 (Russian Federation); Seo, Eun-Suk [Department of Physics and Institute of Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States)

2013-01-20

352

Synchrotron X-ray diagnostics of cutoff shape of nonthermal electron spectrum at young supernova remnants  

Science.gov (United States)

Synchrotron X-rays can be a useful tool to investigate electron acceleration at young supernova remnants (SNRs). At present, since the magnetic field configuration around the shocks of SNRs is uncertain, it is not clear whether electron acceleration is limited by SNR age, synchrotron cooling, or even escape from the acceleration region. We study whether the acceleration mechanism can be constrained by the cutoff shape of the electron spectrum around the maximum energy. We derive analytical formulae of the cutoff shape in each case where the maximum electron energy is determined by SNR age, synchrotron cooling and escape from the shock. They are related to the energy dependence of the electron diffusion coefficient. Next, we discuss whether information on the cutoff shape can be provided by observations in the near future which will simply give the photon indices and the flux ratios in the soft and hard X-ray bands. We find that if the power-law index of the electron spectrum is independently determined by other observations, then we can constrain the cutoff shape by comparing theoretical predictions of the photon indices and/or the flux ratios with observed data which will be measured by NuSTAR and/or ASTRO-H. Such study is helpful in understanding the acceleration mechanism. In particular, it will supply another independent constraint on the magnetic field strength around the shocks of SNRs.

Yamazaki, Ryo; Ohira, Yutaka; Sawada, Makoto; Bamba, Aya

2014-02-01

353

Evolution of Magnetic Fields and Cosmic Ray Acceleration in Supernova Remnants  

CERN Document Server

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

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

2009-01-01

354

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

International Nuclear Information System (INIS)

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

355

The structure of TeV-bright shell-type supernova remnants  

Science.gov (United States)

Aims: Two-dimensional magnetohydrodynamic (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 ?-ray emission is produced via inverse Compton scattering of background soft photons by high-energy electrons accelerated by the shocks of the SNRs. In a previous paper, we showed that since the energy densities of the cosmic microwave background radiation and that of the IR/optical background photons are much higher than that of the photons produced by the same high-energy electrons via the synchrotron process, the observed correlation between X-ray and TeV brightness of SNR RX J1713.7-3946 can be readily explained with the assumption that the energy density of relativistic electrons is proportional to that of the magnetic field. The TeV emissivity is therefore proportional to the magnetic field energy density and MHD simulations can be used to model the TeV structure of such remnants directly. Two-dimensional 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) we reproduce rather complex morphological structure for ?-rays, for example, the bright thin rim and significant asymmetry, suggesting intrinsic variations of the source morphology not related to the structure of the progenitor and environment; and (3) the observed radial profile of several remnants are well reproduced with an ambient medium density of 0.1-1 cm-3. An even lower ambient density leads to a sharper drop of the TeV brightness with radius than what is observed near the outer edge of these remnants. Conclusions: In a turbulent background medium, we can reproduce the observed characteristics of several shell-type TeV SNRs with reasonable parameters except for a higher ambient density than that inferred from X-ray observations.

Yang, Chuyuan; Liu, Siming; Fang, Jun; Li, Hui

2015-01-01

356

The acceleration of high-velocity clouds in supernova remnants  

Science.gov (United States)

Interstellar clouds passed by blast waves emanating from supernova explosions will be accelerated by the ram pressure of the expanding interior shocked gas. We present numerical and analytical solutions for cloud acceleration in this environment, comparing the results with recent observations of faint, high-velocity (greater than 100 km/sec) filaments observed in Cygnus and Vela. Photons from the conductive interface between the clouds and the surrounding medium can provide the ionizing flux necessary for observable optical emission. Several predictions are made, the most important of which is that fast clouds of neutral hydrogen with column densities of about 10 quintillion per sq cm should be observable in 21 cm studies of SNRs.

Mckee, C. F.; Cowie, L. L.; Ostriker, J. P.

1978-01-01

357

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

358

SNR 0104-72.3: A remnant of Type Ia Supernova in a Star-forming region?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 shows that this emission is diffuse, shock-heated plasma, with negligible X-ra...

Lee, Jae-joon; Park, Sangwook; Hughes, John Patrick; Slane, Patrick O.; Burrows, David N.

2010-01-01

359

A Deep Chandra Observation of Oxygen-Rich Supernova Remnant B0049-73.6 in the Small Magellanic Cloud  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report on the initial results from our deep Chandra observation (450 ks) of O-rich supernova remnant (SNR) B0049-73.6 in the Small Magellanic Cloud. We detect small metal-rich ejecta features extending out to the outermost boundary of B0049-73.6, which were not seen in the previous data with a shorter exposure. The central nebula is dominated by emission from reverse-shocked ejecta material enriched in O, Ne, Mg, and Si. O-rich ejecta distribution is relatively smooth thr...

Schenck, Andrew; Park, Sangwook; Burrows, David N.; Hughes, John P.; Lee, Jae-joon; Mori, Koji

2014-01-01

360

Nucleosynthesis in The Oxygen-Rich Supernova Remnant G292.0+1.8 from Chandra X-Ray Spectroscopy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We continue our analysis of the Galactic oxygen-rich supernova remnant (SNR) G292.0+1.8, which was observed with the {\\it Chandra X-ray Observatory}. The high angular resolution {\\it Chandra} data resolve metal-rich ejecta knots as well as the shocked circumstellar medium. X-ray emission from the ejecta material in G292.0+1.8 is dominated by highly ionized O, Ne and Mg. Measured abundance ratios suggest that this material was produced during the hydrostatic evolution of the ...

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

2003-01-01

 
 
 
 
361

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

Directory of Open Access Journals (Sweden)

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

Opsenica Slobodan

2011-01-01

362

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)

363

Spatially Resolved Low Frequency VLA observations of the Supernova Remnant 3C 391  

CERN Document Server

We present VLA images of the supernova remnant (SNR) 3C~391 at 74, 330, and 1465 MHz. This remnant has been known for some time to exhibit a turnover in its integrated radio continuum spectrum at frequencies < 100 MHz, indicative of free-free absorption from thermal ionized gas along the line of sight. For the first time, our data reveal the spatially resolved morphology of the low frequency free-free absorption with a resolution of ~70 arcsec. Contrary to the expectation that such absorption arises from unrelated low density HII regions (or their envelopes) along the line of sight, these data suggest that in this case the absorbing medium is directly linked to the SNR itself. 3C~391 has been shown in a number of recent papers to be interacting with a molecular cloud. Indeed, it exhibits a number of signposts of SNR/molecular cloud shocks including OH (1720 MHz) masers and broad molecular emission lines. Comparison of the regions of strongest 74 MHz absorption with existing X-ray, IR, and molecular data su...

Brogan, C L; Kassim, N E; Dyer, K K

2005-01-01

364

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

365

Comparing supernova remnants around strongly magnetized and canonical pulsars  

CERN Document Server

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 (SNR) surrounding magnetars, and compare our results with all other bright X-ray emitting SNRs, which are associated with Compact Central Objects (CCOs; which are proposed to have magnetar-like B-fields buried in the crust by strong accretion soon after their formation), high-B pulsar...

Martin, J; Torres, D F; Papitto, A

2014-01-01

366

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

367

Photoionization of Galactic Halo Gas by Old Supernova Remnants  

CERN Document Server

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

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

2000-01-01

368

Cold H I clouds near the supernova remnant W44  

International Nuclear Information System (INIS)

The cold H I clouds near the supernova remnant W44 are investigated by the use of the Maryland-Green Bank Survey (Westerhout 1973). Several clouds with a mean diameter of about 20 pc are distributed in the region. They do not seem to make a shell around W44, contrary to the suggestion by Knapp and Kerr (1974) based on the low-resolution data at coarse grids. Some of them form a chain, about 100 pc in length, extending approximately along the galactic equator. It resembles the cold H I cloud near W3 and W4. The major constituent of the clouds is probably the hydrogen molecule, and the total mass of the entire complex amounts to 25,000 81,000 solar masses. The estimated Jeans mass indicates that they will contract to dense molecular clouds. Therefore, it may safely be concluded that the cold H1 cloud complex near W44 is a giant molecular cloud at an early evolutionary stage. 14 references

369

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

370

Discovery of 35 New Supernova Remnants in the Inner Galaxy  

CERN Document Server

We report the discovery of up to 35 new supernova remnants (SNRs) from a 42 arcsec resolution 90cm multi-configuration Very Large Array survey of the Galactic plane covering 4.5 deg< l <22.0 deg and |b| < 1.25 deg. Archival 20cm, 11cm, and 8 micron data have also been used to identify the SNRs and constrain their properties. The 90cm image is sensitive to SNRs with diameters 2.5 arcmin to 50 arcmin and down to a surface brightness limit of about 10^{-21} W m^{-2} Hz^{-1} sr^{-1}. This survey has nearly tripled the number of SNRs known in this part of the Galaxy, and represents an overall 15% increase in the total number of Galactic SNRs. These results suggest that further deep low frequency surveys of the inner Galaxy will solve the discrepancy between the expected number of Galactic SNRs and the significantly smaller number of currently known SNRs.

Brogan, C L; Gaensler, B M; Kassim, N E; Lazio, T J

2006-01-01

371

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

372

Supernova Remnants and Star Formation in the Large Magellanic Cloud  

CERN Document Server

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

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

2010-01-01

373

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

374

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

375

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

Directory of Open Access Journals (Sweden)

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

Patricia Ambrocio-Cruz

2006-01-01

376

Evolution of supernova remnants in different galactic environments, and its effects on supernova statistics  

International Nuclear Information System (INIS)

By examining the interaction between supernova (SJ) ejecta and the various environments in which the explosive event might occur, we conclude that only a small fraction of the many SNs produce observable supernova remnants (SNRs). This fraction, which is found to depend weakly upon the lower mass limit of the Sn progenitors, and more strongly on the specific characteristics of the associated interstellar medium, decreases from approximately 15% near the galactic center to 10% at R/sub gal/ approx.10 kpc and drops nearly to zero for R/sub gal/>15 kpc. Generally, whether a SNR is detectable is determined by the density of the ambient interstellar medium in which it is embedded. We find that SNRs are only detectable above some critical density (napprox.0.1 cm-3). The presence of large, low-density superbubble cavities around stellar associations due to the combined effects of stellar winds and supernova shells strongly suggests that a large portion of the detectable SNRs must have runaway stars as their progenitors. These results explain the differences between the substantially larger SN rates in the Galaxy derived both from pulsar statistics and from observations of SN events in external galaxies, when compared to the substantially smaller SN rates derived from galactic SNR statistics. These results also explain the very large number of SNRs observed toward the galactic center in comparison to few SNRs found in the anticenter directionnticenter direction

377

Discovery of X-Ray Emission from Supernova 1970G with Chandra: Filling the Void between Supernovae and Supernova Remnants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report on the discovery of X-ray emission from SN 1970G in M101, 35 years after its outburst, using deep X-ray imaging with the Chandra X-ray observatory. The Chandra ACIS spectrum shows that the emission is soft (<2 keV) and characteristic for the reverse shock region. The X-ray luminosity (1 x 10^37 ergs/s) is likely caused by the interaction of the supernova (SN) shock with dense circumstellar matter. If the material was deposited by the stellar wind from the progenito...

Immler, Stefan; Kuntz, K. D.

2005-01-01

378

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

International Nuclear Information System (INIS)

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

379

Radio observations of the supernova remnant G 109.1 - 1.0  

International Nuclear Information System (INIS)

The supernova remnant G 109.1-1.0, which contains a periodic X-ray point source, has been observed with the Effelsberg 100-m telescope at 2.7 GHz. The remnant has shell structure at both radio and X-ray wave-lengths and the radio and X-ray maps show similar large-scale emission. No linearly polarized radio emission was detected. G 109.1-1.0 is one of three shell remnants in which the probable stellar remnant has now been found. (author)

380

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

 
 
 
 
381

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 evidensub>sun. Finally, we give evidence for the likely detection of the remnant of the historical supernova, SN1968L.

382

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

383

Dense Gas Towards the RXJ1713.7-3946 Supernova Remnant  

CERN Document Server

We present results from a Mopra 7mm-wavelength survey that targeted the dense gas-tracing CS(1-0) transition towards the young gamma-ray-bright supernova remnant, RXJ1713.7-3946 (SNR G347.3-0.5). In a hadronic gamma-ray emission scenario, where cosmic ray protons interact with gas to produce the observed gamma-ray emission, the mass of potential cosmic ray target material is an important factor. We summarise newly-discovered dense gas components, towards Cores G and L, and Clumps N1, N2, N3 and T1, which have masses of 1-10^4 solar masses. We argue that these components are not likely to contribute significantly to gamma-ray emission in a hadronic gamma-ray emission scenario. This would be the case if RXJ1713.7-3946 were at either the currently favoured distance of ~1kpc or an alternate distance (as suggested in some previous studies) of ~6kpc. This survey also targeted the shock-tracing SiO molecule. Although no SiO emission corresponding to the RXJ1713.7-3946 shock was observed, vibrationally-excited SiO(1-...

Maxted, Nigel I; Dawson, Bruce R; Burton, Michael G; Fukui, Yasuo; Lazendic, Jasmina; Kawamura, Akiko; Horachi, Hirotaka; Sano, Hidetoshi; Walsh, Andrew J; Yoshiike, Satoshi; Fukuda, Tatsuya

2013-01-01

384

The nature of the cosmic-ray electron spectrum, and supernova remnant contributions  

Science.gov (United States)

The observed cosmic-ray (CR) electron spectrum and position fraction e+/(e- + e+) spectrum above 1 GeV are examined, and it is found that a deconvolution of the total spectrum into three components is necessary because of the increase of e+/(e- + e+) above 5 GeV: (1) secondary electrons e+ or e- from the interaction of the CR protons with the interstellar gas provide the total e+ for energies less than 3 GeV, but for energies above 3 GeV these electrons cannot account for the observed positron flux; (2) Electrons (e-) generally thought to derive from supernova remnants (SNRs), probably via shock acceleration, dominate the total spectrum for E of 10 GeV or less but definitely decline relative to total at higher energies; (3) Another (e- + e+) source dominates the total spectrum at E of 40 GeV or greater. The derived spectrum of (2) is consistent in its energy cutoff (though gradual) with that deduced from the observed synchrotron emission of some old SNRs and follows naturally from shock acceleration with synchrotron and inverse Compton scattering losses taken into account. As for (3), nearby pulsars may be important contributors.

Boulares, Ahmed

1989-01-01

385

Dust Formation in the young core-collapse supernova remnant E0102  

CERN Document Server

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

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

2009-01-01

386

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

387

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

388

Inverse Compton Emission from Galactic Supernova Remnants: Effect of the Interstellar Radiation Field  

Energy Technology Data Exchange (ETDEWEB)

The evidence for particle acceleration in supernova shells comes from electrons whose synchrotron emission is observed in radio and X-rays. Recent observations by the HESS instrument reveal that supernova remnants also emit TeV {gamma}-rays; long awaited experimental evidence that supernova remnants can accelerate cosmic rays up to the ''knee'' energies. Still, uncertainty exists whether these {gamma}-rays are produced by electrons via inverse Compton scattering or by protons via {pi}{sup 0}-decay. The multi-wavelength spectra of supernova remnants can be fitted with both mechanisms, although a preference is often given to {pi}{sup 0}-decay due to the spectral shape at very high energies. A recent study of the interstellar radiation field indicates that its energy density, especially in the inner Galaxy, is higher than previously thought. In this paper we evaluate the effect of the interstellar radiation field on the inverse Compton emission of electrons accelerated in a supernova remnant located at different distances from the Galactic Centre. We show that contribution of optical and infra-red photons to the inverse Compton emission may exceed the contribution of cosmic microwave background and in some cases broaden the resulted {gamma}-ray spectrum. Additionally, we show that if a supernova remnant is located close to the Galactic Centre its {gamma}-ray spectrum will exhibit a ''universal'' cutoff at very high energies due to the Klein-Nishina effect and not due to the cut-off of the electron spectrum. As an example, we apply our calculations to the supernova remnants RX J1713.7-3946 and G0.9+0.1 recently observed by HESS.

Porter, Troy A.; /UC, Santa Cruz; Moskalenko, Igor V.; /Stanford U., HEPL; Strong, Andrew W.; /Garching, Max Planck Inst., MPE

2006-08-01

389

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

International Nuclear Information System (INIS)

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

390

Are Models for Core-Collapse Supernova Progenitors Consistent with the Properties of Supernova Remnants?  

CERN Document Server

The recent discovery that the Fe-K line luminosities and energy centroids observed in nearby SNRs are a strong discriminant of both progenitor type and circumstellar environment has implications for our understanding of supernova progenitor evolution. Using models for the chemical composition of core-collapse supernova ejecta, we model the dynamics and thermal X-ray emission from shocked ejecta and circumstellar material, modeled as an $r^{-2}$ wind, to ages of 3000 years. We compare the X-ray spectra expected from these models to observations made with the Suzaku satellite. We also model the dynamics and X-ray emission from Type Ia progenitor models. We find a clear distinction in Fe-K line energy centroid between core-collapse and Type Ia models. The core-collapse supernova models predict higher Fe-K line centroid energies than the Type Ia models, in agreement with observations. We argue that the higher line centroids are a consequence of the increased densities found in the circumstellar environment create...

Patnaude, Daniel J; Slane, Patrick O; Badenes, Carles; Heger, Alexander; Ellison, Donald C; Nagataki, Shigehiro

2015-01-01

391

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

392

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

Directory of Open Access Journals (Sweden)

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

Bernd Aschenbach

2013-12-01

393

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

394

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)

395

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

396

An astrophysics data program investigation of spatial structure of supernova remnants  

Science.gov (United States)

The final report on astrophysics data program investigation of spatial structure of supernova remnants for the period 1 Aug. 1989 to 31 Jul. 1991 is presented. The goal of the project was the study of the spatial structure of supernova remnants (SNR's) as observed in the x-ray band. A number of software tools were developed for the analysis: (1) a program to fit various geometric models to high resolution x-ray data, and (2) programs for Fourier Transform analysis of clumping in SNR's. These programs were applied to high resolution imager (HRI) data on the young galactic SNR's Tycho and Kepler with some success.

Hughes, John P.

1993-01-01

397

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

398

Giant X-ray source in Cygnus (Cygnus superbubble) as a remnant of a peculiar supernova  

International Nuclear Information System (INIS)

The analytic solution of equations for the evolution of supernova remnants in the radiative phase is found. It shows that the X-ray source Cygnus Superbubble might be formed by an explosion with the energy release 1052-1053 erg. The analysis of the light curve of SN 1961 shows that this supernova in the result of an explosion with energy about 2x1052 erg in a supermassive star with the mass of order 103M * where M* is the solar mass. An evolutionary sequence for the formation of giant shell sources is suggested: presupernova - an object of the type R136a, supernova - an explosion of the type SN 1961 and the supernova remnant - a source of the type Cygnus Superbubble

399

Multifrequency study of a new Fe-rich supernova remnant in the Large Magellanic Cloud, MCSNR J0508-6902  

Science.gov (United States)

We present a detailed radio, X-ray and optical study of a newly discovered Large Magellanic Cloud (LMC) supernova remnant (SNR) which we denote as MCSNR J0508-6902. Observations from the Australia Telescope Compact Array (ATCA) and the XMM-Newton X-ray observatory are complemented by deep H? images and Anglo-Australian Telescope AAOmega spectroscopic data to study the SNR shell and its shock ionization. Archival data at other wavelengths are also examined. The remnant follows a filled-in shell-type morphology in the radio continuum and has a size of ˜74 pc × 57 pc at the LMC distance. The X-ray emission exhibits a faint soft shell morphology with Fe-rich gas in its interior - indicative of a Type Ia origin. The remnant appears to be mostly dissipated at higher radio-continuum frequencies leaving only the south-eastern limb fully detectable while in the optical it is the western side of the SNR shell that is clearly detected. The best-fitting temperature to the shell X-ray emission (kT = 0.41^{+0.05}_{-0.06} keV) is consistent with other large LMC SNRs. We determined an O/Fe ratio of <21 and an Fe mass of 0.5-1.8 M? in the interior of the remnant, both of which are consistent with the Type Ia scenario. We find an equipartition magnetic field for the remnant of ˜28 ?G, a value typical of older SNRs and consistent with other analyses which also infer an older remnant.

Bozzetto, L. M.; Kavanagh, P. J.; Maggi, P.; Filipovi?, M. D.; Stupar, M.; Parker, Q. A.; Reid, W. A.; Sasaki, M.; Haberl, F.; Uroševi?, D.; Dickel, J.; Sturm, R.; Williams, R.; Ehle, M.; Gruendl, R.; Chu, Y.-H.; Points, S.; Crawford, E. J.

2014-03-01

400

The Discovery of a Supernova Remnant Embedded in a Giant H II Region of M33  

Science.gov (United States)

We have combined radio, optical, and X-ray data to discover a new supernova remnant (SNR) in M33. This remnant is embedded in the giant H II region NGC 592. Our VLA-WSRT radio survey of M33 showed that NGC 592 has a nonthermal component to its radio emission. Optical images of the H II region at the KPNO 4 m allowed us to subtract the thermal source to reveal the nonthermal source. NGC 592 had also been identified in Einstein data as a soft X-ray source. Our ROSAT observation, combined with the radio and optical data, provides evidence that the X-ray source is a supernova remnant. A knot of [S II] emission was isolated in the H II region, and MMT spectra confirm that the knot has the spectrum of a supernova remnant. We use these observations to investigate the properties of the remnant and its environment. We find that this SNR is a typical middle-aged remnant except that it is expanding into dense gas of the H II region NGC 592. We also find that there is a pressure difference between the hot postshock region and the cool recombination zone. This difference may be a sign that nonthermal particles and magnetic fields provide significant pressure support in the recombination zone.

Gordon, Shawn M.; Kirshner, Robert P.; Duric, Nebojsa; Long, Knox S.

1993-12-01

 
 
 
 
401

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 ×keV ? 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.

402

Updated Radio Sigma-D Relation for Galactic Supernova Remnants  

Science.gov (United States)

We present the 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 (Pavlovic 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. Non-standard orthogonal regression keeps the Sigma-D and D-Sigma relations invariant within estimated uncertainties. Our previous Monte Carlo simulations verified that the slopes of the empirical Sigma-D relation should be determined by using the orthogonal regression, because of its good performances for data sets with severe scatter. The 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 is here slightly steeper (? ? 5.2) than the Sigma-D slope in Paper I (? ? 4.8). The PDF method relies on data points density maps which can provide more reliable calibrations that preserve more information contained in the calibration sample. We estimate distances to five new faint Galactic SNRs discovered for the first time by Canadian Galactic Plane Survey, and obtained distances of 2.3, 4.0, 1.3, 2.9 and 4.7 kiloparsecs for G108.5+11.0, G128.5+2.6, G149.5+3.2, G150.8+3.8 and G160.1-1.1, respectively. The updated empirical relation is used to estimate distances of 160 shell Galactic SNRs and new results chan