SNR¶

class gammapy.astro.source.SNR(e_sn=<Quantity 1.e+51 erg>, theta=<Quantity 0.1>, n_ISM=<Quantity 1. 1 / cm3>, m_ejecta=<<class 'astropy.constants.iau2015.IAU2015'> name='Solar mass' value=1.9884754153381438e+30 uncertainty=9.236140093538353e+25 unit='kg' reference='IAU 2015 Resolution B 3 + CODATA 2014'>, t_stop=<Quantity 1000000. 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 age `t`.
`radius`([t])	Outer shell radius at age t.
`radius_inner`(t[, fraction])	Inner radius at age t of the SNR shell.

Attributes Documentation

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:

\[t_{begin} \approx 200 \ \textnormal{} \left(\frac{E_{SN}}{10^{51}erg}\right)^{-1/2} \left(\frac{M_{ej}}{M_{\odot}}\right)^{5/6} \left(\frac{\rho_{ISM}}{10^{-24}g/cm^3}\right)^{-1/3}\]

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

luminosity_tev(t=None, energy_min=<Quantity 1. TeV>)[source]¶

Gamma-ray luminosity above energy_min at age t.

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:

\[L_{\gamma}(\geq 1TeV) \approx 10^{34} \theta \left(\frac{E_{SN}}{10^{51} erg}\right) \left(\frac{\rho_{ISM}}{1.66\cdot 10^{-24} g/cm^{3}} \right) \textnormal{ph} s^{-1}\]

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:

\[r_{SNR}(t) \approx \left(\frac{E_{SN}}{\rho_{ISM}}\right)^{1/5}t^{2/5}\]

radius_inner(t, fraction=0.0914)[source]¶

Inner radius at age t of the SNR shell.

Parameters:

t : Quantity

Time after birth of the SNR.