pint.models.dispersion_model.FDJumpDM

class pint.models.dispersion_model.FDJumpDM

Bases: Dispersion

This class provides system-dependent DM offsets for narrow-band datasets. Such offsets can arise if different fiducial DMs are used to dedisperse the template profiles used to derive the TOAs for different systems. They can also arise while combining TOAs obtained using frequency- collapsed templates with those obtained using frequency-resolved templates.

FDJumpDM is not to be confused with DMJump, which provides a DM offset without providing the corresponding DM delay. DMJump is specific to wideband datasets whereas FDJumpDM is intended to be used with narrowband datasets.

This component is called FDJumpDM because the name DMJump was already taken, and because this is often used in conjunction with FDJumps which account for the fact that the templates may not adequately model the frequency-dependent profile evolution.

Parameters supported:

Name / Aliases	Description	Kind
FDJUMPDM {flag} {value}	System-dependent DM offset.	pc / cm3

Methods

add_param(param[, deriv_func, setup])	Add a parameter to the Component.
d_delay_d_dmparam(toas, param_name[, acc_delay])	Derivative of delay wrt to DM parameter.
d_dm_d_fdjumpdm(toas, jump_param)	Derivative of DM values w.r.t FDJUMPDM parameters.
dispersion_slope_value(toas)
dispersion_time_delay(DM, freq)	Return the dispersion time delay for a set of frequencies.
dispersion_type_delay(toas)
dm_value(toas)	Compute modeled DM value at given TOAs.
fdjump_dm(toas)	Return the system-dependent DM offset.
fdjump_dm_delay(toas[, acc_delay])	This is a wrapper function for interacting with the TimingModel class
get_params_of_type(param_type)	Get all the parameters in timing model for one specific Parameter subtype.
get_prefix_mapping_component(prefix)	Get the index mapping for the prefix parameters.
is_in_parfile(para_dict)	Check if this subclass included in parfile.
match_param_aliases(alias)	Return the parameter corresponding to this alias.
param_help()	Print help lines for all available parameters in model.
print_par([format])	param format: Parfile output format. PINT outputs the 'tempo', 'tempo2' and 'pint'
register_deriv_funcs(func, param)	Register the derivative function in to the deriv_func dictionaries.
register_dm_deriv_funcs(func, param)	Register the derivative function in to the deriv_func dictionaries.
remove_param(param)	Remove a parameter from the Component.
set_special_params(spcl_params)
setup()	Finalize construction loaded values.
validate()	Validate loaded values.
validate_toas(toas)	Check that this model component has TOAs where needed.

Attributes

aliases_map	Return all the aliases and map to the PINT parameter name.
category
component_types
free_params_component	Return the free parameters in the component.
param_prefixs
register

setup()

Finalize construction loaded values.

validate()

Validate loaded values.

fdjump_dm(toas)

Return the system-dependent DM offset.

The delay value is determined by FDJUMPDM parameter value in the unit of pc / cm ** 3.

fdjump_dm_delay(toas, acc_delay=None)

This is a wrapper function for interacting with the TimingModel class

d_dm_d_fdjumpdm(toas, jump_param)

Derivative of DM values w.r.t FDJUMPDM parameters.

add_param(param: Parameter, deriv_func: Callable | None = None, setup: bool = False)

Add a parameter to the Component.

The parameter is stored in an attribute on the Component object. Its name is also recorded in a list, self.params.

Parameters:

• param (pint.models.Parameter) – The parameter to be added.

• deriv_func (function) – Derivative function for parameter.

property aliases_map: Dict[str, str]

Return all the aliases and map to the PINT parameter name.

This property returns a dictionary from the current in timing model parameters’ aliase to the pint defined parameter names. For the aliases of a prefixed parameter, the aliase with an existing prefix index maps to the PINT defined parameter name with the same index. Behind the scenes, the indexed parameter adds the indexed aliase to its aliase list.

d_delay_d_dmparam(toas, param_name, acc_delay=None)

Derivative of delay wrt to DM parameter.

Parameters:

• toas (pint.TOAs object.) – Input toas.

• param_name (str) – Derivative parameter name

• acc_delay (astropy.quantity or numpy.ndarray) – Accumulated delay values. This parameter is to keep the unified API, but not used in this function.

dispersion_time_delay(DM, freq)

Return the dispersion time delay for a set of frequencies.

This equation is taken from Duncan Lorimer, Michael Kramer, Handbook of Pulsar Astronomy, Second edition, Page 86, Equation [4.7] Here we assume the reference frequency is at infinity and the EM wave frequency is much larger than plasma frequency.

dm_value(toas)

Compute modeled DM value at given TOAs.

Parameters:

toas (TOAs object or TOA table(TOAs.table)) –

If given a TOAs object, it will use the whole TOA table in the

TOAs object.

Return type:

DM values at given TOAs in the unit of DM.

property free_params_component: List[str]

Return the free parameters in the component.

This function collects the non-frozen parameters.

Return type:

A list of free parameters.

get_params_of_type(param_type: str) → List[str]

Get all the parameters in timing model for one specific Parameter subtype.

get_prefix_mapping_component(prefix: str) → Dict[int, str]

Get the index mapping for the prefix parameters.

Parameters:

prefix (str) – Name of prefix.

Returns:

A dictionary with prefix parameter real index as key and parameter name as value.

Return type:

dict

is_in_parfile(para_dict: Dict) → bool

Check if this subclass included in parfile.

Parameters:

para_dict (dictionary) – A dictionary contain all the parameters with values in string from one parfile

Returns:

Whether the subclass is included in the parfile.

Return type:

bool

match_param_aliases(alias: str) → str

Return the parameter corresponding to this alias.

Parameters:

alias (str) – Alias name.

Note

This function only searches the parameter aliases within the current component. If one wants to search the aliases in the scope of TimingModel, please use TimingModel.match_param_aliase().

param_help() → str

Print help lines for all available parameters in model.

print_par(format: Literal['tempo', 'tempo2', 'pint'] = 'pint') → str

Parameters:

format (str, optional) – Parfile output format. PINT outputs the ‘tempo’, ‘tempo2’ and ‘pint’ format. The defaul format is pint. Actual formatting done elsewhere.

Returns:

str

Return type:

formatted line for par file

register_deriv_funcs(func: Callable, param: str) → None

Register the derivative function in to the deriv_func dictionaries.

Parameters:

• func (callable) – Calculates the derivative

• param (str) – Name of parameter the derivative is with respect to

register_dm_deriv_funcs(func, param)

Register the derivative function in to the deriv_func dictionaries.

Parameters:

• func (callable) – Calculates the derivative

• param (str) – Name of parameter the derivative is with respect to

remove_param(param: str | Parameter) → None

Remove a parameter from the Component.

Parameters:

param (str or pint.models.Parameter) – The parameter to remove.

validate_toas(toas) → None

Check that this model component has TOAs where needed.