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Supernova remnants (SNR) as ideal
laboratories of hot plasmas
Koyama Katsuji, Kyoto, and Osaka University
Allow me to make an excuse remark …
(1) To specialist (astronomer) = OK
What are Chandrasekhar mass, Hubble
constant, Stellar structure, SN and SNR.
(2) To general public (citizen) = OK
Big bang, Black hole
Between (1) and (2) is very difficult.
My talk is limited area of Astronomy
: Hot plasma and Nucleosynthesis in SNRs
Immediate after (0.4 Mys) the Big Bang: Chaos:
“Ripples on the Pacific Ocean” only H, He
100 G stars
http://sci.esa.int/planck/
Cluster
of
Galaxies
C, O, Si, Fe
Q: when and where ?
A: SN, SNR
After14 Gys: Islands: Cosmos
What is SN, SNR ?
By nuclear fusion, massive stars accumulate
heavy elements in the interior
(1) >10 M◎ : Fe core
 Core collapse
supernova (CC SN:
He, C, Ne, O)
(2) 8-10 M◎ :C, Ne, O
(white dwarf:
degeneracy pressure)
Explosive fusion
Ia supernova (Ia SN : Fe)
Supernova Remnant
(SNR)= Shock Heated
Hot Plasma
C+Ne+O
white dwarf
degeneracy
pressure
Hot Plasma
Space Plasma vs Laboratory Plasma
Fundamental physics
and
Physical parameters
are obtained from
Laboratory Work
Applied to the Space
Space proper
Science
Are laboratory works always more accurate
and reliable than the space ? No !
Steady nuclear fusion in laboratory is very
difficult, almost impossible  to keep hot
plasma for long time is difficult.
Laboratory plasma is always transient
in a short time scale.
Space plasma is also transient, but the
time scale is extremely long  quasi-stable
Space is better than laboratory to study
transient plasma
Q: What is transient in the SNR plasma ?
A: Shock-heating and relaxation process
Transient Plasma =Ionizing plasma (IP)
Expanding velocity (v)
Random velocity (T)
Free
Expansion( v)
X
Shock
Heated
Gas
In most of the SNR,
Te > Tz (IP) .
Standard Scenario
Electron temperature, Te
Ionization temperature: Tz
Time t (~1000 ys)
IP : (Te > Tz)
 CIE (Te=Tz)
X-ray
Spectrum
of IC 443
(CC SNR)
Ohnishi et al. 2013
Ne
Mg
Si
Fe
S
Ar
Ca
All these lines come from
highly ionized atoms
No laboratory spectrum is like this !
Temperature kTe~ 0.6 keV is too low to make
highly ionized iron  Tz is higher than 0.6 keV
to excite the lines  Recombination of free electron
Discovery of Te< Tz plasma
= Ｒｅｃｏｍｂｉｎｇ Ｐｌａｓmａ (RP)
He-like ion:
Excitation electron < Recombination of free electron
RRC
1S
1
Origin of Recombining Plasma
Rarefaction in an early phase of CC SN
High density Circum Stellar Medium (CSM ) Te=Tz 
Break out to low density Inter Stellar Medium (ISM)
Adiabatic expansion  Te is cooled down Te<Tz
log r
(pc)
ISM
Low density
1
RP
0
CSM
High density
log t (year)
1
2
3
From these line fluxes, we can determine the
abundance of each element
Ne
Mg
Si
Fe
S
Ar
Ca
The key issue is whether the plasma is
ionizing, recombining, or equilibrium and
what is the transient time
Whether ionizing or recombining, and the transient
time, historical SNe are important. We can depict
the data of each time epoch, then can make
quantitative model (theory).
10
11
12 log t (s)
This is my
“Star-of-bethlehem”
SN1006
SN1573
(Tycho’s SN)
SN1604
(Kepler’s SN
SN185 : Himiko
unified Japan
(Yamatai Koku)
Southern
Cross
Time history of recombination and ionization
1
Recombining
Plasma
0.1
Bare Ion
H-like
He-like
0.01
9
Iron Ion Fraction
10
Li-like
log t (s) for
11
n=1cm-3
12
Ionizing
plasma
We know the ion fraction from the spectrum , then
we can obtain the abundances of each element
Nucleosynthesis in massive star 1
Ia Supernova
: Ia SN
8-10 M◎ :C, Ne, O
(white dwarf)
 Explosive
fusion (Si--Fe)
C+Ne+O
white dwarf
 Si--Fe
SN1006
Fujiwara, Teika (藤原定家）
Meigetsuki (明月記）, Vol 52
一條院 寛弘三年 四月二日
葵酉 夜以降 騎官中 有大客
星 如螢惑 光明動耀 連夜正
見南方 或云 騎陣将軍星本
体 増変光
Constellation
star
Uchida et al. 2013
Then 1000 years after
Koyama et al. 1996
Ia
SN
CC
SN
100 ly
Nucleosynthesis in massive star 2
Core collapse
supernova
: CC SN
>10 M◎
He, C, Ne, O, Si
SNR
observations are
“Anatomy” of
massive stars
Ia
CC
The progenitor stars
are constrained
to be ~25 M◎
Yasumi et al. 2013
Another topics : To thermal equilibrium, but in
SN1006 opposite evolution (high temperature
component becomes much higher).
High energy electrons = Synchrotron radiation
Ex=3keV (B/1μG)(Ee/1014 eV)2
Koyama et al. 1996
SN1006
Fermi Acceleration
2003-4-09
2012-4-23
V=6000 km/s
Winkler et al. 2013
Ping-Pong
ball
on the
moving
frame
Cosmic Rays : The Highest Energy Particles in
the Universe : What is the Accelerator ?
E-2.7
Knee Energy
~1015 eV
E-3.0
Bellow Knee, Galactic Origin
Above Knee, Extra Galactic
LHC
What is an
injector to the
Fermi
accelerator ?
SN1006:
Synchrotron
Radiation =
Power-law with
index Γ
North Rim
East Rim
Flatter Γ  Higher efficiency for the acceleration
Γ vs kT North Rim vs East Rim
Koyama &Bamba 2006
Γ-map
kT-map
Flatter Γ is from higher kT
Injector is a high energy tail of hot plasma
Conclusion
1. Space is better for the transient
plasma than laboratory.
2. Using the transient plasma physics,
we have established the
Nucleosynthesis of stars and supper
novae.
3. Anti-equilibrium of temperature:
the Fermi acceleration is discovered
in the SNR plasma
Thank you
Rarefaction in an early phase
Canonical Diffusive Shock Acceleration
Emax～ (v/2000 km/s)(B/10μG) 1014 eV
< Knee Energy (1015 eV)
log r
(pc)
ＩSM
Low density
1
0
CSM
High density
log t (year)
1
2
3
Another big problem is missing energy
Kinematic energy (=1/2Mv2) of Ia and CC SN
are ~1051 erg. A large fraction should be
converted to the thermal energy: kT = 3mv2/16
However observed thermal energy (kTe) is
~1049 erg
This large missing energy would be
contained in protons and other ions (the ion
temperature kTi).
But, no evidence is so far observed.
Space plasma proper problem: large
scale low density plasma.
Solved by the observation of Tycho SNR
Te=TFe me/mFe , 10-5 at the reverse shock front (RS)
Then TFe  Te as time goes.
Question: How quick this energy
Free
Expansion( v)
transfer process.
Parameter β
X
β=10-5 (slow transfer)
RS
-- 100 (very rapid tarnsfer)
RS
1-ly
Energies of Kα & Kβ ,
and intensity ratio
(Kα/Kβ ) are functions
of Te and distribution
of ion fraction.
These are
determined by β and nt.
Simulations are
right panels;
The results are,
n~2×10-24 g/cm3
β ~ 0.01 (large
energy is still in ions)
Thank you again