scholarly journals Non-Equilibrium Ionization X-ray Emission from Supernova Remnants

1983 ◽  
Vol 101 ◽  
pp. 99-107
Author(s):  
J. Michael Shull
Keyword(s):  
Supernova Remnants ◽  
Heavy Element ◽  
Plasma Temperature ◽  
Supernova Explosion ◽  
Theoretical Models ◽  
Astrophysical Plasmas ◽  
Ionization Equilibrium ◽  
X Ray ◽  
Elemental Abundances ◽  
Stellar Nucleosynthesis

X-ray spectra of young supernova remnants (SNR's) are perhaps the most spectacular examples of hot, line-emitting astrophysical plasmas. Heated to temperatures of 1 to 10 keV and enriched with the heavy element products of stellar nucleosynthesis, the plasma inside these SNR's emits prodigiously in lines of 0, Ne, Mg, Si, S, Ar, Ca, and Fe. Theoretical models of this emission provide measures of the plasma temperature and density, elemental abundances, and the degree of approach to ionization equilibrium. Thus, astrophysicists are offered the opportunity to test their understanding of the supernova explosion, its interaction with the interstellar medium, and the nucleo-synthetic processes which enrich our galaxy with heavy elements.

scholarly journals X-Ray Spectroscopic Measurements of Non-Equilibrium Ionization in Supernova Remnants

1984 ◽  
Vol 86 ◽  
pp. 76-79
Author(s):  
T.H. Markert ◽  
C.R. Canizares ◽  
T. Pfafman ◽  
P. Vedder ◽  
P.F. Winkler ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
X Rays ◽  
Ionization Equilibrium ◽  
X Ray ◽  
Elemental Abundances ◽  
Ion Collisions ◽  
Ionization Structure ◽  
Cool Plasma ◽  
Collisional Ionization ◽  
Time Required

When a cool plasma is shock-heated to X-ray temperatures, the ionization structure does not attain its final, equilibrium value immmediately, but proceeds toward it through electron-ion collisions with a timescale τ ≡ net of order 1012 cm−3 sec. For supernova remnants (SNRs), where 0.1 ≤ ne ≤ 10 cm−3 typically, the time required to achieve collisional ionization equilibrium (CIE) can be greater than the age of the remnant. Even if the SNR is quite old, that part of the remnant which is emitting most of the X-rays may have been shocked relatively recently, so that the assumption of CIE may be inappropriate (see below).The question of ionization equilibrium is of great astrophysical importance in the study of SNRs because it affects the deduced values of their masses and elemental abundances (e.g. Shull 1982). Mass determinations are affected because underionized plasma generally has a much higher emissivity in soft X-rays than equilibrium plasma. Unless this is accounted for, the deduced value of the density and therefore of the mass, will be considerably overestimated.

scholarly journals High Resolution X-ray Spectra of Supernova Remnants

1983 ◽  
Vol 101 ◽  
pp. 205-211
Author(s):  
C. R. Canizares ◽  
P. F. Winkler ◽  
T. H. Markert ◽  
C. Berg
Keyword(s):  
Supernova Remnants ◽  
Abundance Ratio ◽  
Ionization Equilibrium ◽  
X Ray ◽  
Cygnus Loop ◽  
Doppler Shifts ◽  
Wide Range ◽  
Cas A ◽  
Einstein Observatory ◽  
Tycho’S Snr

We review results obtained with the Focal Plane Crystal Spectrometer (FPCS) on the Einstein Observatory. Clear evidence is found for departures from ionization equilibrium in the interior of Puppis A. This comes from the observed weakness of the forbidden lines relative to the resonance lines for the He - like triplets of O VII and Ne IX. However, it is shown that this departure from equilibrium does not alter our conclusion, based on previous FPCS results, that O and Ne are overabundant relative to Fe. The spectrum of N132D shows strong O VIII emission and very weak Fe emission, suggesting an even greater O/Fe abundance enhancement than in Puppis A. In the Cygnus Loop, the O to Ne abundance ratio is approximately solar; we have no information about Fe. The O VII triplet shows clear evidence for departures from ionization equilibrium in the Cygnus Loop. The spectrum of Tycho's SNR contains lines from ionization stages of Fe XVII through Fe XXIII and XXIV, indicating that a wide range of ionization conditions are present. Cas A and Kepler's SNR show relatively less emission from the higher ionization stages. For Tycho, we measured the strength of the strong Si XIII lines, and we find that a many-fold overabundance of Si relative to Fe is required regardless of the equilibrium state of the emitting plasma (confirming the Solid State Spectrometer results). On a separate topic, the completed analysis of X-ray Doppler shifts in Cas A suggests that the emitting material is concentrated in a ring that is inclined to the line of sight and is expanding at ~5000 km s−1.

scholarly journals Observing the Nucleosynthesis from Core Collapse Supernovae

1988 ◽  
Vol 108 ◽  
pp. 383-393
Author(s):  
Claes Fransson
Keyword(s):  
Supernova Remnants ◽  
Direct Evidence ◽  
Optical Observations ◽  
Core Collapse ◽  
Valuable Insight ◽  
Sources Of Information ◽  
X Ray ◽  
Stellar Nucleosynthesis ◽  
Plasma Effects ◽  
Indirect Sources

Since the appearance of the classical papers on stellar nucleosynthesis in the 1950’s most of the observational tests have been through indirect sources of information. Even though this has been rather successful (cf. various contributions in this volume), it represents only an average over all sources, yielding little information about specific stars. The most direct evidence comes from observations of young galactic supernova remnants (age less than ∼103 years). Unfortunately, the analysis of X-ray data are hampered by a lack of understanding of the detailed physics, eg. non-equilibrium and plasma effects, as well as by observational problems (Itoh and Nomoto, 1987). Optical observations (cf. Raymond, 1984) have given some valuable insight of eg. the oxygen-rich remnants. The analysis of these are, however, suffering from the fact that only a small fraction of the mass is seen in the optical.

Mixed-morphology supernova remnants: the case of SNR 0520–69.4 in the Large Magellanic Cloud

2020 ◽  
Vol 499 (3) ◽  
pp. 4213-4222
Author(s):  
I Ramírez-Ballinas ◽  
J Reyes-Iturbide ◽  
P Ambrocio-Cruz ◽  
R Gabbasov ◽  
M Rosado
Keyword(s):  
Supernova Remnants ◽  
Plasma Temperature ◽  
Optical Emission ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Physical Parameters ◽  
X Ray ◽  
Hot Plasma ◽  
Observatory Data ◽  
Fabry Perot

ABSTRACT We present observations in X-ray and optical emission of the supernova remnant (SNR) 0520–69.4 in the Large Magellanic Cloud. Using XMM–Newton observatory data, we produced images of the diffuse X-ray emission and spectra to obtain the X-ray parameters, such as luminosity and temperature, of hot plasma in the SNR. Diffuse X-ray emission with filled-centre morphology goes beyond the Hα region, suggesting that the hot gas escapes through the pores of the Hα shell. We fitted a model that has a plasma temperature of 1.1 × 107 K for an X-ray thermal luminosity of 3.3 × 1035 erg s−1. However, from Hα and [O iii] Fabry–Perot observations obtained with the Marseille Hα Survey of the Magellanic Clouds and the Milky Way at La Silla, European Southern Observatory, we are able to obtain physical parameters such as the velocity of the shock induced in the cloudlets emitting at optical wavelengths and the electron density of this gas. With the parameters described above, we test the model proposed by White & Long (1991, ApJ, 373, 543) for explaining the mixed-morphology observed.

scholarly journals Einstein Observatory Limits on Neutron Star Surface Temperatures

1987 ◽  
Vol 125 ◽  
pp. 457-457
Author(s):  
F.R. Harnden
Keyword(s):  
Star Formation ◽  
Neutron Star ◽  
Neutron Stars ◽  
Supernova Remnants ◽  
Theoretical Models ◽  
X Ray ◽  
Star Models ◽  
Formation And Evolution ◽  
Star Surface ◽  
Einstein Observatory

For years the theoretical models of neutron star formation and evolution had remained largely unconstrained by observation. Following the Einstein X-ray Observatory surveys of supernova remnants and pulsars, however, strict temperature limits were placed on many putative neutron stars. The Einstein search for additional objects in the class of supernova remnants with embedded pulsars has increased the number of such objects by two. For the four objects in this class, the surface temperature limits (see Table 1) provide meaningful logically sound constraints on the neutron star models. For the future, however, still better X-ray observations are needed, both to increase the number of objects available for study and to refine the spatial and spectral capabilities of the X-ray measurements.

scholarly journals Models for the Emission Line Spectra of Oxygen-rich Supernova Remnants

1987 ◽  
Vol 40 (6) ◽  
pp. 789 ◽  
Author(s):  
Michael A Dopita
Keyword(s):  
Supernova Remnants ◽  
Optical Emission ◽  
Theoretical Modelling ◽  
Optical Data ◽  
X Ray ◽  
Elemental Abundances ◽  
Current State ◽  
Enormous Amount ◽  
Degree Of Confidence ◽  
Cas A

The mechanism of excitation of the oxygen-rich class of young supernova remnants (SNRs), typified by the fast-moving knots of Cas A, is not currently understood. In this paper we review the available optical data and the current state of attempts at theoretical modelling. A new model is proposed which dramatically improves the fit of the theory with the observations for this class of SNRs. The model is of an X-ray driven R-type ionisation front precursor of a very fast shock. The peculiarities of the thermal balance in oxygen allow an enormous amount of superheating in the gas, which is first exposed to the X-ray ionising field, and the optical emission occurs in this superheated gas. The fit with observation is sufficiently good to give some degree of confidence that the mode of excitation of the plasma has at last been identified, and elemental abundances in four young oxygen-rich SNRs are derived.

scholarly journals Powering central compact objects with a tangled crustal magnetic field

2020 ◽  
Vol 495 (2) ◽  
pp. 1692-1699 ◽  
Author(s):  
Konstantinos N Gourgouliatos ◽  
Rainer Hollerbach ◽  
Andrei P Igoshev
Keyword(s):  
Magnetic Field ◽  
Supernova Remnants ◽  
Initial Conditions ◽  
Supernova Explosion ◽  
Compact Objects ◽  
Dipole Field ◽  
Ohmic Dissipation ◽  
X Ray ◽  
Axisymmetric Structure ◽  
Central Compact Objects

ABSTRACT Central Compact Objects (CCOs) are X-ray sources with luminosity ranging between 1032 and 1034 erg s−1, located at the centres of supernova remnants. Some of them have been confirmed to be neutron stars. Timing observations have allowed the estimation of their dipole magnetic field, placing them in the range ∼1010–1011 G. The decay of their weak dipole fields, mediated by the Hall effect and Ohmic dissipation, cannot provide sufficient thermal energy to power their X-ray luminosity, as opposed to magnetars whose X-ray luminosities are comparable. Motivated by the question of producing high X-ray power through magnetic field decay while maintaining a weak dipole field, we explore the evolution of a crustal magnetic field that does not consist of an ordered axisymmetric structure, but rather comprises a tangled configuration. This can be the outcome of a non-self-excited dynamo, buried inside the crust by fallback material following the supernova explosion. We find that such initial conditions lead to the emergence of the magnetic field from the surface of the star and the formation of a dipolar magnetic field component. An internal tangled magnetic field of the order of 1014 G can provide sufficient Ohmic heating to the crust and power CCOs, while the dipole field it forms is approximately 1010 G, as observed in CCOs.

scholarly journals A New Aspect of Galactic Ridge X-ray Emission: — SNRS in a Tenuous Medium? —

1987 ◽  
Vol 125 ◽  
pp. 535-543
Author(s):  
Katsuji Koyama
Keyword(s):  
Supernova Remnants ◽  
Plasma Temperature ◽  
X Ray ◽  
Significant Contributor

Thin thermal natures of a plasma temperature of several keV are observed in the diffuse X-ray spectra from the galactic ridge region by the Tenma satellite. Within the constraints imposed by the observational results, possible origins of the ridge X-ray emission are discussed. We show that unidentified young supernova remnants in a tenuous medium could be a significant contributor to the ridge emission.

scholarly journals Tests for Supernova Explosion Models: from Light Curves to X-ray Emission of Supernova Remnants

2005 ◽  
Vol 192 ◽  
pp. 269-274
Author(s):  
Elena Sorokina ◽  
Sergey Blinnikov
Keyword(s):  
Supernova Remnants ◽  
Gamma Ray ◽  
Broad Band ◽  
Supernova Explosion ◽  
Light Curves ◽  
Evolutionary Stage ◽  
X Ray ◽  
Points Of View ◽  
Frequency Radiation

SummaryThe 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.

scholarly journals Atomic Data Needs for X-ray Astronomy

2002 ◽  
Vol 12 ◽  
pp. 82-83
Author(s):  
Nancy S. Brickhouse
Keyword(s):  
High Resolution ◽  
Atomic Data ◽  
Ionization Mechanism ◽  
Ionization State ◽  
Astrophysical Plasmas ◽  
X Ray ◽  
Physical Conditions ◽  
Elemental Abundances ◽  
The Status ◽  
Collisional Ionization

AbstractWith the launches of the Chandra X-ray Observatory and XMM-Newton, high resolution X-ray spectra of cosmic sources are broadening our understanding of the physical conditions, such as temperature, density, ionization state, and elemental abundances. X-ray emitting astrophysical plasmas can be generally classified by their dominant ionization mechanism, either collisional ionization or X-ray photoionization. The atomic data needs are significantly different for these two cases; however, for both cases it is important that we identify robust and accurate diagnostics and that we verify completeness of the broadband models. We discuss the status of the atomic data currently used in atomic databases for X-ray astronomy, in view of theoretical and experimental atomic physics considerations.

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