SNR研究におけるCTAと他波長との連携
Yutaka Ohira Aoyama Gakuin University
Contents
Cosmic rays and Supernova remnants
Spectral index of accelerated particles
Observations of SNRs

SummaryGalactic cosmic ray
SNRs are though to be the originof the Galactic CR.
What Type? Isolated or in superbubbles?

Galactic CR spectrum
dN/dE ∝ E-2.75 (E<1015.5eV)
Source spectrum

Qsour-2.1-2.4∝E

DSA model

Q ∝ E-2
Inconsistent ?

Eknee=1015.5eV(1particle /m2/yr)
Gaisser 2006

Observations of SNRs
s=2.2 for SN1006

RadioX-ray

Cassam-Chenai et al. 2008TeV g-ray

Acero et al. 2010

Radio：e- acceleration up to GeV (~300 SNRs)
X ray：e- acceleration up to TeV(~10 SNRs)
GeV-g：p acceleration up to TeV(~10 SNRs)
TeV-g：e- or p accelerations up to 10TeV(~10SNRs)
15.5
50-2-2
Ha 10 eV?, 10 erg/SN?, Kep = 10 ?, dN/dE∝E ?

Diffusive Shock Acceleration(DSA)

ScholerdN/dE ∝ E-s

u1/u2 + 2s = u /u - 1 = 2
1 2

Axford 1977, Krymsky 1977, Blandford&Ostriker 1978, Bell 1978

Effects on the spectral index
dN/dE ∝E-s
Standard DSA theorys = 2 Blandford & Ostriker, 1978

CR pressures < 2 Drury & Volk, 1981

Alfven wave drifts > 2 Zirakashvili & Ptuskin, 2009

Escape of CRs > 2 Ohira,Murase,Yamazaki, 2010

Anisotropys > 2 Bell et al., 2011

Neutral particles

s > 2 Ohira, 2012, Blasi et al. 2012

Sub diffusions > 2 Kirk et al., 1996

2nd order Fermis = ? Fermi, 1949

Synchrotron radiation from accelerated eRelativistic e- + Magnetic field  Synchrotron radiation
dNe-/dE∝E-s  Fn∝n-(s-1)/2nsyn = 0.29 g2 Wce / 2p ~ 5×106 Hz×EGeV2 BmG
1 GeV e- + 300mG  nsyn ~ 1.5 GHz

10 GeV e- + 300mG  nsyn ~ 150 GHz
100 GeV e- +3mG  nsyn ~ 150 GHz

100 GeV e- + 10mG  nsyn ~ 500 GHz
Radio synchrotron is important for 1-100 GeV e-

Spectral index in SNRs, s
Spectral index of radio synchrotron flux, fn∝n - aReynolds et al., 2011, SSR
Not universal?

a = (s-1)/2dN/dE∝E-s
a = 0.5 for s=2aYoung SNRs (SN1006）
Radial profile ofX-ray intensity

下流

上流Thin widthSynchrotron cooling B~100mG
Berezhko et al.,2003, A&A, 412, L11

Leptonic の問題: Small B、TeV specrum

Hadronicの問題: sproton = 2.0 < selectron ~ 2.2
Which is better ?

Acero et al.,2010, A&A, 516, A62

CTA can identify the emission mechanism?

Young SNRs （RXJ1713）
Abdo et al., 2011, ApJ, 734, 28

Uchiyama et al., 2007, Nature~1yr time variability of x rays
tacc, tcool ~ 1yr B~1mG B-field amplification？

Can CTA observe the time variability?
Wp < 0.3×1051(n/0.1cm3)-1erg

Young SNRs （Tycho）
Giordano et al, arXiv:1008.0265

X-ray thin filaments
g-ray flux
 B~100mG
接触不連続面と先進衝撃波の間が狭い
 Compression ratio r > 4

s = (r+2)/(r-1) s < 2dN/dE∝E-s

電波、ガンマ線スペクトルは s = 2.3 < 2 （ Cas A も s > 2 )加速された電子が少ない? CTAによるTeV領域の高精度観測が必要

Young SNRs (Tycho, SN1006)
Tycho

X rayReynolds et al., 2011, SSR

RadioThin filaments are observed not only in x ray but also in radio.
 Magnetic damping? (M. Pohl et al., 2005, ApJL)
Where are electrons accelerated? Shock? Downstream? CD?

Young SNRs (Magnetic Field)
Tycho

Everywhere,radial direction
for young SNRs
(Dickel & Milne, 1976)

Why?
Rayleigh-Taylor instability?
(e.g. Schure, 2010)
Upstream densityfluctuations?
(Zirakashvili&Ptuskin, 2008)

Reynoso et a., 1997, ApJ

Young SNRs (RCW86)
Helder et al.,Science, 2009

HaCR pressure?

Vink et al., 2006

RCW86の場合、固有運動から衝撃波速度 ush~6000±2800 km/s が観測されている。
Tp = 3mpush2/16 = 70 keV
広い方の幅は、2.2 keVの温度に対応
 CRがエネルギーを持ち去った？
狭い方の幅も広い  Tup ~ 30-100eV
 CRが上流を加熱？

Effects of neutral hydrogen atoms
Ohira et al.(2009), Ohira & Takahara (2010), Ohira(2012)Young SNRs （Cas A）
a<0.77

fsyn,n∝n - p
Anderson & Rudnick 1996

dN/dE∝E-s

a = (s-1)/2<a>~0.77
a>0.82a= 0.77 s=2.54

Hard spectra at inner regions
Soft spectra at outer regions

Comparing the g-ray index with radio index,
we can identify the emission region.

Middle-aged（104yr） SNRs （W44）
Break
Color : 2-10GeV
Contour : 4.5μm IR(shocked H2)

Very steep

Broken power law
Very steep spectrum (N(E)∝E-3)
Abdo et al., 2010, Science, 327, 1103

Escape of CRs from SNRs
SNRs interacting with MC.

Ohira,Murase,Yamazaki, MNRAS, 2011

Middle-aged（104yr） SNRs（Fermi SNRs）

Radio vs TeV?

Uchiyama 2011

Middle-aged SNRs（Magnetic field）
Young SNRs

Old SNRs

Milne, 1987

Middle-aged（104yr） SNRs （H3+）

Indriolo et al., 2010

Tavani et al., 2010

Ionization by Galactic CRs

IC443

IC443 GeV-TeV g rayIndriolo et al., 2009

Absorption by H3+  CR ionization rate

CR + H2  CR + H2+ + eH2 + H2+  H3+ + H

H3+ + e- H2 + H or H + H + H

Ionization = recombinationz2n(H2) = kenen(H3+)
 z2 ~ 10-15 s-1 > 10-16 s-1

Very Young SNRs (SN1987A)
100GHzIndex

tage ~ 25 yr , dN/dE ∝ E-2.4

Lakicevic et al. 2012

The spectral index is not uniform.
Broken power law spectrum
tcool,syn ~ 1.5×1010 yr×BmG-2 EGeV-1~ 10 yr×B100mG-3/2 nsyn,10GHz-1/2

Cooling break?
B field amplification

Very Young SNRs (SN1993J)
Marti-Vidal et al., 2011tage ~ 20yr , dN/dE ∝ E-2.55
g-ray flux of extragalacitc SNRs

Image courtesy of NRAO/AUI and N. Bartel, M.
Bietenholz, M. Rupen, et al.

Very Young PWNe? (SN1986J)
g-ray flux of extragalacitc PWNe

If radiative efficiency > 1%,
extragalactic PWNe canbe observed by CTA!

Bietenholz et al.,2010

http://iopscience.iop.org/0004-637X/712/2/1057/fulltext/

Summary
Standard DSA predicts dN/dE∝E-2
Observations show s ≠ 2. dN/dE∝E-s
CTAによるスペクトルの決定は理論への制限に重要！
TeVガンマ線の放射領域がSNR内で決められないとき、indexによって決めることが可能。Index の決定精度が重要！
Magnetic field is strongly amplified around SNR shocks
IC成分のスペクトルとFluxの決定が重要Magnetic field directions are radial for young SNRs
and tangential for old SNRs
About 50 very young SNRs (Radio Supernovae)have been observed.
CTA will be able to observe extragalactic SNRs and PWNe