The Evolution of Supernova Remnants and the Structure of the Interstellar Medium

Author(s):  
Christopher F. McKee
2021 ◽  
Vol 366 (6) ◽  
Author(s):  
Hidetoshi Sano ◽  
Yasuo Fukui

AbstractWe review recent progress in elucidating the relationship between high-energy radiation and the interstellar medium (ISM) in young supernova remnants (SNRs) with ages of ∼2000 yr, focusing in particular on RX J1713.7−3946 and RCW 86. Both SNRs emit strong nonthermal X-rays and TeV $\gamma $ γ -rays, and they contain clumpy distributions of interstellar gas that includes both atomic and molecular hydrogen. We find that shock–cloud interactions provide a viable explanation for the spatial correlation between the X-rays and ISM. In these interactions, the supernova shocks hit the typically pc-scale dense cores, generating a highly turbulent velocity field that amplifies the magnetic field up to 0.1–1 mG. This amplification leads to enhanced nonthermal synchrotron emission around the clumps, whereas the cosmic-ray electrons do not penetrate the clumps. Accordingly, the nonthermal X-rays exhibit a spatial distribution similar to that of the ISM on the pc scale, while they are anticorrelated at sub-pc scales. These results predict that hadronic $\gamma $ γ -rays can be emitted from the dense cores, resulting in a spatial correspondence between the $\gamma $ γ -rays and the ISM. The current pc-scale resolution of $\gamma $ γ -ray observations is too low to resolve this correspondence. Future $\gamma $ γ -ray observations with the Cherenkov Telescope Array will be able to resolve the sub-pc-scale $\gamma $ γ -ray distribution and provide clues to the origin of these cosmic $\gamma $ γ -rays.


2020 ◽  
Vol 496 (2) ◽  
pp. 2448-2461 ◽  
Author(s):  
Matteo Pais ◽  
Christoph Pfrommer ◽  
Kristian Ehlert ◽  
Maria Werhahn ◽  
Georg Winner

ABSTRACT Galactic cosmic rays (CRs) are believed to be accelerated at supernova remnant (SNR) shocks. In the hadronic scenario, the TeV gamma-ray emission from SNRs originates from decaying pions that are produced in collisions of the interstellar gas and CRs. Using CR-magnetohydrodynamic simulations, we show that magnetic obliquity-dependent shock acceleration is able to reproduce the observed TeV gamma-ray morphology of SNRs such as Vela Jr and SN1006 solely by varying the magnetic morphology. This implies that gamma-ray bright regions result from quasi-parallel shocks (i.e. when the shock propagates at a narrow angle to the upstream magnetic field), which are known to efficiently accelerate CR protons, and that gamma-ray dark regions point to quasi-perpendicular shock configurations. Comparison of the simulated gamma-ray morphology to observations allows us to constrain the magnetic coherence scale λB around Vela Jr and SN1006 to $\lambda _B \simeq 13_{-4.3}^{+13}$ pc and $\lambda _B \gt 200_{-40}^{+50}$ pc, respectively, where the ambient magnetic field of SN1006 is consistent with being largely homogeneous. We find consistent pure hadronic and mixed hadronic-leptonic models that both reproduce the multifrequency spectra from the radio to TeV gamma-rays and match the observed gamma-ray morphology. Finally, to capture the propagation of an SNR shock in a clumpy interstellar medium, we study the interaction of a shock with a dense cloud with numerical simulations and analytics. We construct an analytical gamma-ray model for a core collapse SNR propagating through a structured interstellar medium, and show that the gamma-ray luminosity is only biased by 30 per cent for realistic parameters.


1983 ◽  
Vol 101 ◽  
pp. 385-392
Author(s):  
Donald P. Cox

We observe the heating of interstellar material in young supernova remnants (SNR). In addition, when analyzing the soft X-ray background we find evidence for large isolated regions of apparently hot, low density material. These, we infer, may have been heated by supernovae. One such region seems to surround the Sun. This has been modeled as a supernova remnant viewed from within. The most reasonable parameters are ambient density no ~ 0.004 cm−3, radius of about 100 pc, age just over 105 years (Cox and Anderson 1982).


1970 ◽  
Vol 39 ◽  
pp. 229-235
Author(s):  
L. Woltjer

The nature of the supernova event is still poorly understood. A variety of models has been proposed and the interpretation of the observations remains ambiguous. About all that is certain is that in the supernova event much of the matter is ejected at speeds of typically 10 000 km sec−1 and that about 1049 erg of visible light is emitted. The amount of matter ejected and the bolometric correction to be applied to the optical radiation are very uncertain. The discovery of a pulsar in two supernova remnants (Crab Nebula and Vela X) suggests that frequently a neutron star or other condensed object results following the outburst.


1999 ◽  
Vol 190 ◽  
pp. 28-31 ◽  
Author(s):  
R. Chris Smith ◽  

The Magellanic Clouds are unique in providing sites to study the interstellar medium (ISM) and its components at all scales. To promote the pursuit of such studies, we have begun the Magellanic Cloud Emission-line Survey (MCELS), a deep imaging survey of both of these nearby galaxies in the emission of Hα, [S II], and [O III]. The emission-line images will be used in detailed optical and multiwavelength studies of H II regions, supernova remnants, planetary nebulae, superbubbles, and supergiant shells. Together with parallel surveys at other wavelengths, this survey will provide the foundation upon which to build a deeper understanding of the ISM in the Clouds and other galaxies, from small scales (~1 pc) all the way up to global scales. We present a sample of recent and current work using the MCELS dataset.


2013 ◽  
Vol 9 (S296) ◽  
pp. 378-379 ◽  
Author(s):  
Hui Zhu ◽  
Wenwu Tian

AbstractSupernova remnants (SNRs) play a key role in understanding supernovae explosion mechanisms, exploring the likely sources of Galactic cosmic rays and the chemical enrichment of interstellar medium (ISM). Reliable distance determinations to Galactic SNRs are key to obtain their basic parameters, such as size, age, explosion energy, which helps us to study their environment and interstellar medium. We review the methods to determine the distances to SNRs and highlight the kinematic distance measurement by Hi absorption and CO emission observations.


1983 ◽  
Vol 101 ◽  
pp. 289-293
Author(s):  
R. Petre ◽  
C. R. Canizares ◽  
P. F. Winkler ◽  
F. D. Seward ◽  
R. Willingale ◽  
...  

We present soft X-ray photomosaic images of two supernova remnants, Puppis A and IC 443, constructed from a series of exposures by the Einstein imaging instruments. The complex morphologies displayed in these images reflect the interaction between “middle-aged” supernova remnants and various components of the interstellar medium. Surface brightness variations across Puppis A suggest that inhomogeneities on scales from 0.2 to 30 pc are present in the interstellar medium, while the structure of IC 443 is apparently dominated by the interaction between the remnant and a giant molecular cloud.


1998 ◽  
Vol 188 ◽  
pp. 281-282
Author(s):  
Y. Fujita ◽  
J. Fukumoto ◽  
K. Okoshi

Theoretical arguments indicate that the ISM is inhomogeneous; Mathews estimated that the ~ 1M⊙ of metal ejected by each supernova event into the ISM is trapped locally within the hot bubbles. Since in elliptical galaxies, there is no overlapping of expanding supernova remnants after galactic wind period, it is expected that this inhomogeneity persists for a long time. The observations also suggests that the ISM of elliptical galaxies is inhomogeneous. Based on these arguments, we studied the evolution of the multiphase (inhomogeneous) ISM.


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