ExpDisk

class dysmalpy.models.ExpDisk(baryon_type='gas+stars', **kwargs)[source]

Bases: MassModel, _LightMassModel

Infinitely thin exponential disk (i.e. Freeman disk)

Parameters:

total_mass (float) – Log of total mass of the disk in solar units
r_eff (float) – Effective radius in kpc
baryon_type ({'gas+stars', 'stars', 'gas'}) – What type of baryons are included. Used for dlnrhogas/dlnr

Attributes Summary

`mass_to_light`
`param_names`	Names of the parameters that describe models of this type.
`r_eff`
`rd`
`total_mass`
`tracer`

Methods Summary

`circular_velocity`(r)	Circular velocity as a function of radius
`dlnrhogas_dlnr`(r)	Exponential disk asymmetric drift term
`enclosed_mass`(r)	Enclosed mass as a function of radius
`evaluate`(r, total_mass, r_eff, mass_to_light)	Mass surface density of a thin exponential disk
`light_profile`(r)	Conversion from mass to light as a function of radius
`rhogas`(r)	Mass surface density as a function of radius

Attributes Documentation

mass_to_light = DysmalParameter('mass_to_light', value=1.0, fixed=True, prior=<dysmalpy.parameters.UniformPrior object>)

param_names = ('total_mass', 'r_eff', 'mass_to_light')

Names of the parameters that describe models of this type.

The parameters in this tuple are in the same order they should be passed in when initializing a model of a specific type. Some types of models, such as polynomial models, have a different number of parameters depending on some other property of the model, such as the degree.

When defining a custom model class the value of this attribute is automatically set by the Parameter attributes defined in the class body.

r_eff = DysmalParameter('r_eff', value=1.0, bounds=(0, 50), prior=<dysmalpy.parameters.UniformPrior object>)

rd

total_mass = DysmalParameter('total_mass', value=1.0, bounds=(5, 14), prior=<dysmalpy.parameters.UniformPrior object>)

tracer = 'mass'

Methods Documentation

circular_velocity(r)[source]

Circular velocity as a function of radius

Parameters:: r (float or array) – Radii at which to calculate the enclosed mass
Returns:: vcirc – Circular velocity in km/s
Return type:: float or array

dlnrhogas_dlnr(r)[source]

Exponential disk asymmetric drift term

Parameters:: r (float or array) – Radius in kpc
Returns:: log_drhodr – Log surface density derivative as a function or radius
Return type:: float or array

Notes

See [1] for derivation and specificall Equations 3-11

References

enclosed_mass(r)[source]

Enclosed mass as a function of radius

Parameters:: r (float or array) – Radii at which to calculate the enclosed mass
Returns:: menc – 1D enclosed mass profile
Return type:: float or array

static evaluate(r, total_mass, r_eff, mass_to_light)[source]: Mass surface density of a thin exponential disk

light_profile(r)[source]

Conversion from mass to light as a function of radius

Parameters:: r (float or array) – Radii at which to calculate the enclosed mass
Returns:: light – Relative line flux as a function of radius
Return type:: float or array

rhogas(r)[source]

Mass surface density as a function of radius

Parameters:: r (float or array) – Radii at which to calculate the enclosed mass
Returns:: surf_dens – Mass surface density at r in units of Msun/kpc^2
Return type:: float or array