haruo yasuda & herman lee - ncsu
Post on 11-May-2022
6 Views
Preview:
TRANSCRIPT
Haruo Yasuda & Herman Lee Department of Astronomy, Kyoto university, Japan; yasuda@kusastro.kyoto-u.ac.jp
12) Time evolution of broadband non-thermal emission from supernova remnants in different circumstellar environments
Introduction
Method�:�CR-Hydrodynamics
Supernova remnants (SNRs) are thought to be one of the major acceleration sites of galactic cosmic rays (CRs) and emit broadband non-thermal electromagnetic radiation owing to their interactions with the interstellar matters (ISM) or circumstellar matter (CSM).
・π0 decay : interaction between CR-proton and ISM/CSM gas
・Inverse Compton (IC) : interaction between CR-electron and low-energy photon
γ
γ
π0
gas p+
CR p+
CR e-
high γlow γ (Cosmic Microwave Background radiation; CMB)
Epeak ∼ 1 keV
Epeak ∼ 1 TeV
× (Ee,max
10 TeV )2
( B10 μG )
2
× (Ee,max
10 TeV )2
IC
Synchrotron
EF(E
)[
MeV
cm−
2s−
1]
E [ eV ]1012109106 101510310010−310−610−9
10−2
10−5
10−8
∼ 10 TeV (Ep,max
100 TeV )2
π0 decay
@mπc2 ∼ 200 MeVCutoff
Epeak
EF(E
)[
MeV
cm−
2s−
1]
E [ eV ]1012109106 101510310010−310−610−9
10−5
10−8
10−2
spectral�shape
adiabatic cooling
non-thermal cooling
p [ mpc ]
p4f(
p)[
cgs
]
10−3 10310010−6
10−21
10−18
10−24
radiation�cooling
∂n(E)∂t
= −dEdt
n(E) + Q(E)
Synchrotron IC
π0
Brems
EF(E
)[
MeV
cm−
2s−
1]
E [ eV ]101210910610310010−310−610−9
10−2
10−5
10−8
non-thermal�emissions
Ptot(x) ≡ Pg(x) + PCR(x) + PB(x)
PCR(x) =4π3 ∫
pmax
pinj
p3v fp(x, p) dp, PB(x) =B(x)2
8π
CR magnetic
feedback�of�CR
gas
γeff
γeff − 1Ptot =
γgas
γgas − 1Pgas +
γCR
γCR − 1PCR
(ii)�effective�specific�ratio������:�γeff
(i)�total�pressure�������:�Ptot
・modify�hydro�eqs.�&�EoS�����������������������using�CR�pressure
50 yr 500 yr
5,000 yr1.0 cm−30.1 cm−30.01 cm−3
EF(E
)[
MeV
cm−
2s−
1]
E [ eV ]
10−6
10−9
10−3
101210910610310010−310−6 101210910610310010−310−6 101210910610310010−310−6
nISM =
10−6M⊙/yr10−5M⊙/yr 10−4M⊙/yr 50 yr
500 yr5,000 yr
EF(E
)[
MeV
cm−
2s−
1]
E [ eV ]
10−6
10−9
10−3
101210910610310010−310−6 101210910610310010−310−6 101210910610310010−310−6
·M =
Calibration�test
https://www.nasa.gov/mission_pages/GLAST/news/cosmic-rays-source.html
Cassiopeia A
γ-ray
γ-rayX-ray
radio
Multi-wavelength�observation�of�SNRs
Emission�mechanisms�of�γ-ray
i) < 1,000 yr
ii) < 5,000 yriii) > 10,000 yr
EF(E
)[
MeV
cm−
2s−
1]
E [ eV ] 1012109107 1015
10−3
10−5
10−8
i) < 1,000 yr : π0 decay (hadronic)? ii) < 5,000 yr : IC (leptonic)? iii) > 10,000 yr : π0 decay (hadronic)
●�Questions�:�
・We develop the hydro code which can self-consistently solve the hydrodynamics coupling with effective particle acceleration.
Rsk, Vsk, Tage, B0, T0fp(x, p), fe(x, p)
i) uniform model ii) power-law model
To�fix�many�SNR�and�DSA�parameters,�we�reproduce��the�hydro�and�multi-wavelength�observations�at�the�same�time.
Results：time-evolution�of�SED
ρ[
gcm
−3
]
E [ eV ]
R [ pc ]
EF(E
)[
MeV
cm−
2s−
1]
10−25
10−23
10−24
54321
10−2
10−5
10−8
101210910610310010−310−6
Tycho (446yr)
π0 decaySynchrotron
ρ[
gcm
−3
]
E [ eV ]
R [ pc ]
EF(E
)[
MeV
cm−
2s−
1]
10−25
10−24
10−26
109876 11
101210910610310010−310−6
10−2
10−5
10−8
RX J1713 (1625yr)
ICsynchrotron
leptonicmixed
10−6 M⊙/yr leptonic
hadronichadronic
mixedhadronic leptonic
mixed10−5 M⊙/yr10−4 M⊙/yr
50 yr 5,000 yr500 yr
leptonicmixed hadronic
0.01 cm−3
0.1 cm−3
1.0 cm−3
leptonicleptonicleptonic
hadronichadronichadronic
Tage = > 10,000 yr
leptonichadronic hadronicNo obs.
uniform ISM
power-law CSM
previous picture
Summary
constantly increase・π0 decay :
shift to lower energy・IC :
constantly decrease・π0 decay :
constantly increase・IC :
i) uniform model
ii) power-law model
(i) We�find�that�the�time-evolution�of�γ-ray�is�characterized�by������density�and�B-field�of�cirucmstellar�environment.(ii)�We�acquire�the�relationship�between�γ-ray�spectrum�and��������the�circumstellar�environment.
Environment�model
※ Full ionized gas is assumed
AcknowlegmentThis presentation is supported by the “UCHUGAKU” project of the Unit of Synergetic Studies for Space, Kyoto University.
Ptot, γeff
∂u∂t
= −∂Ptot
∂m
∂E∂t
= −∂(Ptotu)
∂m∂r∂m
=1
4πr2ρ
Hydrodynamics
Forward shock (FS)
Contact discontinuity (CD)
Reverse shock (RS)
ISM CSM
Supernova (SN) ejecta
ρ[
gcm
−3
]
R [ pc ]
E =12
ρu2 +Ptot
γeff − 1
・code : VH-1・spherical symmetric SN-like explosion→ two ejecta model (i) exponential (Dwarkadas+1998) (ii) power-law (Truelove+1999) {u(x) − vA(x)}
∂ f(x, p)∂x
− Q(x, p) =
diffusion
injection∂∂x {D(x, p)
∂ f(x, p)∂x } +
d{u(x) − vA(x)}dx
p3
∂ f(x, p)∂p
Nonlinear�diffusive�shock�acceleration�(NLDSA)
convection
Kep
fMB fNT p+
e-
p [ mpc ]
p4f(
p)[
cgs
]
・solve diffusion-convection equation at shock using semi-analytic model (Capliori+2010a,b)・“thermal-leakage” injection (Blasi+2004,2005)
−∞ 0+0− x
u(x)
u0
Upstream Downstream
Precursor
u1,TP
u2,TP
u1
u2
acceleration
・Magnetic field amplification (MFA) (Bell+1978a,b)
・considering energy-loss due to (i) non-thermal radiation (ii) adiabatic expansion
・4-components as emission (i) π0 decay (ii) Synchrotron (iii) IC (iv) Bremsstrahlung
・We follow time-evolution of γ-ray from SNRs in different circumstellar environments.
R [ pc ]
ρ[
gcm
−3
]
B 0[
μG]
10−22
10−25
10−23
10−24
0 54321
10−5
10−6
10−7
B(r) = B0
ρ(r) = μHmpnISM
R [ pc ]
ρ[
gcm
−3
]
B 0[
μG]
10−22
10−25
10−23
10−24
0 54321
10−5
10−6
10−7
ρ(r) =·M
4πVw
1r2
B(r) =(σw
·MVw)1/2
r
・We prepare two environment models(i) uniform ISM model : the environment as Type Ia SN (ii) power-law CSM model : swept by stellar wind before CC SN
→ Free parameters : ejecta mass explosion energyMej, ESN,ISM number density magnetic fieldnISM, B0,CSM mass-loss rate wind velocity magnetization ratio·M, Vw, σw
(i) (ii)
↪︎ fixed from calibration test using observation data of SNRs except nISM, ·M
★Main results
These trends are affected by 2 factors : (i) shocked mass i.e. density (ii) energy-loss by
synchrotron i.e. B-field
②�Can�we�see�the�trend�in�observed�γ-ray?①�Whatʼs�the�origin�of�γ-ray�from�SNR?
③�What�makes�these�trend�if�exists?
top related