Electron density models for AGN jets

The gammaALPs.nel.jet.NelJet class simply models the electron density as a power law with

\[n^\mathrm{jet}_\mathrm{el}(r) = n^\mathrm{jet}_0 \left(\frac{r}{r_0}\right)^{\beta}.\]

A more realistic model is provided in the gammaALPs.nel.jet.NelJetHelicalTangled class, which takes into account the fact that inside a relativistic AGN jet, we are not dealing with a cold thermal plasma, see, e.g., [Davies2021]. In this scenario, the effective photon mass in the plasma is not just the plasma frequency (as it is in a cold thermal plasma) – it has to be calculated with an integral over the electron energy distribution function. Once the actual effective photon mass has been found, an “effective” electron density can be used which would give a plasma frequency in a cold plasma equal to the actual effective photon mass within the jet.

Reference / API

class gammaALPs.nel.jet.NelJet(n0, r0, beta)

Bases: object

Class to set characteristics of electron density of AGN Jet

__call__(r)

Calculate the electron density as function from cluster center

Parameters:

r (array-like) – n-dim array with distance from cluster center in pc

Returns:

nel – n-dim array with electron density in cm**-3

Return type:

ndarray

__init__(n0, r0, beta)

Initialize the class

Parameters:

• n0 (float) – electron density in cm**-3

• r0 (float) – radius where electron density is equal to n0 in pc

• beta (float) – power-law index of distance dependence of electron density

property beta

property n0

property r0

class gammaALPs.nel.jet.NelJetHelicalTangled(n0, r0, R0, alpha, beta)

Bases: object

Class to get effective electron densities in jet, taking into account that the jet is not a cold plasma. i.e. the electron distribution is non-thermal.

property R0

__call__(r, R)

Calculate the effective electron density as function from cluster center. Done by finding actual electron density and actual photon effective masses, then making effective mass = w_pl(n_eff) to get n_eff.

Parameters:

• r (array-like) – n-dim array with distance from BH in pc

• R (array-like) – n-dim array with jet widths at R in pc

Returns:

nel – n-dim array with electron density in cm**-3

Return type:

ndarray

__init__(n0, r0, R0, alpha, beta)

Initialize the class

Parameters:

• n0 (float) – electron density in cm^-3

• r0 (float) – radius where electron density is equal to n0 in pc

• R0 (float) – jet width at r0 in pc

• alpha (float) – power-law index of electron energy distribution function

• beta (float) – power-law index of distance dependence of electron density

property alpha

property beta

get_photon_mass_ne(alpha, ne)

Function to calculate effective photon mass from electron distribution, here derived from the electron density and power-law index.

Parameters:

• alpha (float) – power-law index

• ne (array-like) – electron density in cm^-3

Returns:

m_T_2 – effective photon mass squared

Return type:

float

property n0

property r0