agnslim, AGN super-Eddington accretion model

A broadband spectral model for a super-Eddington black hole accretion disc developed by Kubota & Done (2019; KD19). This is based on the slim disc emissivity ( Abramowicz et al., 1988; Watarai et al., 2000; Sadowski, 2011), where radial advection keeps the surface luminosity at the local Eddington limit, resulting in $L(r) \propto r^{-2}$ rather than the $r^{-3}$ expected from the Novikov-Thorne (standard, sub-Eddington) disc emissivity. This is the only major change from the sub-Eddington agnsed model (Kubota & Done 2018; KD18, an updated version of optxagnf (Done et al. (2012)). The flow is radially stratified, with an outer standard disc (from $R_{out}$ to $R_{warm}$), an inner hot Comptonising region ($R_{in}$ to $R_{hot}$) and an intermediate warm Comptonising region to produce the soft X-ray excess ($R_{warm}$ to $R_{hot}$). A minor difference from agnsed is that the disc is assumed to extend untruncated down to the inner radius of the flow, $R_{in}$. This can be below the innermost stable circular orbit as pressure forces are important. By default, the code calculates its own expected value of $R_{in}$ given the mass accretion rate. However, we also allow this to be a free parameter e.g. for use for the extreme super Eddington mass accretion rates probably truncate at some radius from strong wind mass loss. Another minor difference from agnsed is that we do not calculate the reprocessed emission as the geometry of the inner disc is very uncertain but it probably shields the outer flow.

The model calculates some useful quantities, such as the radius at which the flux first goes above the local Eddington limit, and the inner radius of the flow. These are not normally displayed but can be seen by inputting the command chatter 20, and getting the model to recalculate the fit e.g. by changing the normalisation to 1.0001. Set this back to the default of chatter 10 to suppress all this information if further fits are required.

Parameters for agnslim:

par1	mass, black hole mass in solar masses
par2	dist, comoving (proper) distance in Mpc
par3	logmdot, mdot = Mdot/Mdot_Edd where eta Mdot_Edd c$^2$ = L_Edd
par4	astar, dimensionless black hole spin
par5	cosi, cosine of the inclination angle i for the warm Comptonising component and the outer disc.
par6	kTe_hot, electron temperature for the hot Comptonisation component in keV. If this parameter is negative then only the hot Comptonisation component is used.
par7	kTe_warm, electron temperature for the warm Comptonisation component in keV. If this parameter is negative then only the warm Comptonisation component is used.
par8	Gamma_hot, the spectral index of the hot Comptonisation component.
par9	Gamma_warm, the spectral index of the warm Comptonisation component. If this parameter is negative then only the outer disc component is used.
par10	R_hot, outer radius of the hot Comptonisation component in Rg
par11	R_warm, outer radius of the warm Comptonisation component in Rg
par12	logrout, log of the outer radius of the disc in units of Rg. If this parameter is negative, the code will use the self gravity radius as calculated from Laor & Netzer (1989).
par13	R_in, the inner radius of the disc in Rg. If this parameter is -1 (the default), the model will use the radius calculated from KD19. This must be greater than R_hot for mdot greater than 6 and greater than R_isco for mdot less than 6.
par14	redshift
norm	this must be fixed to 1.

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Last modified: Friday, 23-Aug-2024 13:20:40 EDT