Parameters

The zdm package uses a hierarchical parameter system organized into dataclasses. All parameters are accessible through the State object.

State Object

The State object is the central configuration container:

from zdm import parameters

state = parameters.State()

# Access parameter groups
print(state.cosmo.H0)      # Cosmology parameters
print(state.energy.gamma)  # Energy parameters
print(state.host.lmean)    # Host galaxy parameters

Updating Parameters

Single parameter update:

state.update_param('H0', 70.0)

Multiple parameter update via dictionary:

vparams = {
    'cosmo': {'H0': 70.0},
    'energy': {'gamma': -1.1}
}
state.update_param_dict(vparams)

Cosmology Parameters (cosmo)

Parameters for Lambda-CDM cosmology. Default values from Planck18.

Parameter	Default	Unit	Description
`H0`	67.66	km/s/Mpc	Hubble constant
`Omega_k`	0.0	–	Curvature density parameter
`Omega_lambda`	0.6889	–	Dark energy density parameter
`Omega_m`	0.3111	–	Matter density parameter
`Omega_b`	0.0490	–	Baryon density parameter
`Omega_b_h2`	0.0224	–	Baryon density times h^2
`fix_Omega_b_h2`	True	–	Keep Omega_b_h2 fixed when varying H0

FRB Demographics Parameters (FRBdemo)

Parameters controlling FRB source population evolution.

Parameter	Default	Unit	Description
`source_evolution`	0	–	Evolution function: 0=SFR^n, 1=(1+z)^(2.7n)
`alpha_method`	1	–	Scaling method: 0=k-correction, 1=rate interpretation
`sfr_n`	1.77	–	Scaling of FRB rate with star-formation rate
`lC`	3.3249	–	log10 rate constant (Gpc^-3 day^-1 at z=0)

Energy Parameters (energy)

Parameters for the FRB luminosity/energy function.

Parameter	Default	Unit	Description
`lEmin`	30.0	log10(erg)	Minimum FRB energy
`lEmax`	41.84	log10(erg)	Maximum FRB energy
`alpha`	1.54	–	Spectral index (rate ~ nu^alpha)
`gamma`	-1.16	–	Luminosity function slope
`luminosity_function`	2	–	LF type: 0=power-law, 1=gamma, 2=spline+gamma, 3=gamma+linear+log10

Host Galaxy Parameters (host)

Parameters for the host galaxy DM contribution.

Parameter	Default	Unit	Description
`lmean`	2.16	log10(pc/cm^3)	Log-mean of host DM distribution
`lsigma`	0.51	log10(pc/cm^3)	Log-sigma of host DM distribution

Milky Way Parameters (MW)

Parameters for Galactic DM contributions.

Parameter	Default	Unit	Description
`ISM`	35.0	pc/cm^3	Assumed DM for Galactic ISM
`DMhalo`	50.0	pc/cm^3	DM contribution from Galactic halo
`halo_method`	0	–	Halo model: 0=uniform, 1=Yamasaki & Totani, 2=Das+
`sigmaDMG`	0.0	–	Fractional uncertainty in Galactic ISM DM
`sigmaHalo`	15.0	pc/cm^3	Uncertainty in halo DM
`logu`	False	–	Use log-normal for DMG distributions

IGM Parameters (IGM)

Parameters for the intergalactic medium DM distribution.

Parameter	Default	Unit	Description
`logF`	-0.49	–	log10(F), cosmic web fluctuation parameter

Width Parameters (width)

Parameters for intrinsic FRB width distribution.

Parameter	Default	Unit	Description
`Wlogmean`	-0.29	log10(ms)	Log-mean of intrinsic width distribution
`Wlogsigma`	0.65	log10(ms)	Log-sigma of intrinsic width distribution
`Wmethod`	2	–	Width method: 0=ignore, 1=intrinsic, 2=+scattering, 3=+z-dep, 4=specific
`WidthFunction`	2	–	Width function: 0=log-constant, 1=log-normal, 2=half-lognormal
`WNbins`	12	–	Number of width bins
`Wthresh`	0.5	–	Starting fraction for width histogramming

Scattering Parameters (scat)

Parameters for FRB scattering distribution.

Parameter	Default	Unit	Description
`Slogmean`	-1.3	log10(ms)	Mean of log-scattering distribution at 600 MHz
`Slogsigma`	0.2	log10(ms)	Sigma of log-scattering distribution
`Sfnorm`	1000	MHz	Reference frequency for scattering
`Sfpower`	-4.0	–	Frequency scaling power-law index
`ScatFunction`	2	–	Scattering function: 0=log-constant, 1=lognormal, 2=half-lognormal
`Sbackproject`	False	–	Calculate p(tau\|w,DM,z) arrays

Repeater Parameters (rep)

Parameters for repeating FRB population models.

Parameter	Default	Unit	Description
`lRmin`	-3.0	log10(day^-1)	Minimum repeater rate
`lRmax`	1.0	log10(day^-1)	Maximum repeater rate
`Rgamma`	-2.375	–	Differential index of repeater density
`RC`	0.01	–	Constant repeater density
`RE0`	1e39	erg	Energy at which rates are defined

Analysis Parameters (analysis)

Parameters controlling analysis behavior.

Parameter	Default	Unit	Description
`NewGrids`	True	–	Generate new z-DM grids
`sprefix`	“Std”	–	Calculation detail: “Full” or “Std”
`min_lat`	-1.0	degrees	Minimum absolute Galactic latitude
`DMG_cut`	None	pc/cm^3	Maximum DMG to include