SNR¶
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class
gammapy.astro.source.
SNR
(e_sn=<Quantity 1e+51 erg>, theta=<Quantity 0.1>, n_ISM=<Quantity 1.0 1 / cm3>, m_ejecta=<Constant name='Solar mass' value=1.9891e+30 uncertainty=5e+25 unit='kg' reference="Allen's Astrophysical Quantities 4th Ed.">, t_stop=<Quantity 1000000.0 K>, age=None, morphology='Shell2D', spectral_index=2.1)[source]¶ Bases:
object
Simple supernova remnant (SNR) evolution model.
The model is based on the Sedov-Taylor solution for strong explosions.
Reference: http://adsabs.harvard.edu/abs/1950RSPSA.201..159T
Parameters: e_sn :
Quantity
SNR energy (erg), equal to the SN energy after neutrino losses
theta :
Quantity
Fraction of E_SN that goes into cosmic rays
n_ISM :
Quantity
ISM density (g cm^-3)
m_ejecta :
Quantity
Ejecta mass (g)
t_stop :
Quantity
Post-shock temperature where gamma-ray emission stops.
Attributes Summary
sedov_taylor_begin
Characteristic time scale when the Sedov-Taylor phase of the SNR’s evolution begins. sedov_taylor_end
Characteristic time scale when the Sedov-Taylor phase of the SNR’s evolution ends. Methods Summary
luminosity_tev
([t, energy_min])Gamma-ray luminosity above energy_min
at aget
.radius
([t])Outer shell radius at age t. radius_inner
(t[, fraction])Inner radius at age t of the SNR shell. Attributes Documentation
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sedov_taylor_begin
¶ Characteristic time scale when the Sedov-Taylor phase of the SNR’s evolution begins.
Notes
The beginning of the Sedov-Taylor phase of the SNR is defined by the condition, that the swept up mass of the surrounding medium equals the mass of the ejected mass. The time scale is given by:
\[t_{begin} \approx 200 \ \textnormal{} \left(\frac{E_{SN}}{10^{51}erg}\right)^{-1/2} \left(\frac{M_{ej}}{M_{\odot}}\right)^{5/6} \left(\frac{\rho_{ISM}}{10^{-24}g/cm^3}\right)^{-1/3}\]
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sedov_taylor_end
¶ Characteristic time scale when the Sedov-Taylor phase of the SNR’s evolution ends.
Notes
The end of the Sedov-Taylor phase of the SNR is defined by the condition, that the temperature at the shock drops below T = 10^6 K. The time scale is given by:
\[t_{end} \approx 43000 \textnormal{ } \left(\frac{m}{1.66\cdot 10^{-24}g}\right)^{5/6} \left(\frac{E_{SN}}{10^{51}erg}\right)^{1/3} \left(\frac{\rho_{ISM}}{1.66\cdot 10^{-24}g/cm^3}\right)^{-1/3}\]
Methods Documentation
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luminosity_tev
(t=None, energy_min=<Quantity 1.0 TeV>)[source]¶ Gamma-ray luminosity above
energy_min
at aget
.The luminosity is assumed constant in a given age interval and zero before and after. The assumed spectral index is 2.1.
Reference: http://adsabs.harvard.edu/abs/1994A%26A...287..959D (Formula (7)).
Parameters: t :
Quantity
Time after birth of the SNR.
energy_min :
Quantity
Lower energy limit for the luminosity.
Notes
The gamma-ray luminosity above 1 TeV is given by:
\[L_{\gamma}(\geq 1TeV) \approx 10^{34} \theta \left(\frac{E_{SN}}{10^{51} erg}\right) \left(\frac{\rho_{ISM}}{1.66\cdot 10^{-24} g/cm^{3}} \right) \textnormal{ph} s^{-1}\]
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radius
(t=None)[source]¶ Outer shell radius at age t.
Parameters: t :
Quantity
Time after birth of the SNR.
Notes
The radius during the free expansion phase is given by:
\[r_{SNR}(t) \approx 0.01 \textnormal{} \left(\frac{E_{SN}}{10^{51}erg}\right)^{1/2} \left(\frac{M_{ej}}{M_{\odot}}\right)^{-1/2} t\]The radius during the Sedov-Taylor phase evolves like:
\[r_{SNR}(t) \approx \left(\frac{E_{SN}}{\rho_{ISM}}\right)^{1/5}t^{2/5}\]
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