1202.4620 (Yutaka Ohira)
Yutaka Ohira
The interstellar medium is not necessary fully ionized. When a shock
propagates into the partially ionized medium, some neutral particles leak into
the upstream region from the downstream region. In this paper, we investigate
how leakage neutral particles affect the upstream structure of the shock and
particle accelerations. By using four fluid approximations (upstream ions,
upstream neutral particles, leakage neutral particles and pickup ions), we
provide analytical solutions of the precursor structure due to leakage neutral
particles. It is shown that the upstream flow is decelerated in the precursor
and the shock compression ratio becomes smaller than that of the strong shock
limit, but the total compression ratio is the same as that of the strong shock
limit. Even if leakage of neutral particles is small (a few percents of
upstream particles), this smaller compression ratio of the shock can explain
steep gamma-ray spectra from young supernova remnants.
View original:
http://arxiv.org/abs/1202.4620
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