pint.models.pulsar_binary.PulsarBinary

class pint.models.pulsar_binary.PulsarBinary[source]

Bases: DelayComponent

Base class for binary models in PINT.

This class provides a wrapper for internal classes that do the actual calculations. The calculations are done by the classes located in pint.models.stand_alone_psr_binary.

Binary models generally support the below parameters, although some may support additional parameters and/or remove/ignore some of these.

Model parameters:

T0 - time of (any) periastron (MJD)

PB - binary period (days, non-negative)

PBDOT - time derivative of binary period (s/s)

A1 - projected orbital amplitude, $a sin i$ (ls, non-negative)

A1DOT - time derivative of projected orbital amplitude (ls/s)

ECC (or E) - eccentricity (no units, 0<=ECC<1)

EDOT - time derivative of eccentricity (1/s)

OM - longitude of periastron (deg)

OMDOT - time derivative of longitude of periastron (deg/s)

M2 - companion mass for Shapiro delay (solMass, non-negative)

SINI - system inclination (0<=SINI<=1)

FB0 - orbital frequency (1/s, alternative to PB, non-negative)

FBn - time derivatives of orbital frequency (1/s**(n+1))

The internal calculation code uses different names for some parameters:

Eccentric Anomaly: E (not parameter ECC)

Mean Anomaly: M

True Anomaly: nu

Eccentric: ecc

Longitude of periastron: omega

Projected semi-major axis of orbit: a1

Parameters supported:

Name / Aliases	Description	Kind
PB	Orbital period	d
PBDOT	Orbital period derivative respect to time	number
A1	Projected semi-major axis of pulsar orbit, ap*sin(i)	ls
A1DOT / XDOT	Derivative of projected semi-major axis, d[ap*sin(i)]/dt	ls / s
ECC / E	Eccentricity	number
EDOT	Eccentricity derivative respect to time	1 / s
T0	Epoch of periastron passage	d
OM	Longitude of periastron	deg
OMDOT	Rate of advance of periastron	deg / yr
M2	Companion mass	solMass
SINI	Sine of inclination angle	number
FB{number}	0th time derivative of frequency of orbit	1 / s

Methods

`FBX_description`(n)
`FBX_unit`(n)
`add_param`(param[, deriv_func, setup])	Add a parameter to the Component.
`apply_units`()	Apply units to parameter value.
`binarymodel_delay`(toas[, acc_delay])	Return the binary model independent delay call.
`change_binary_epoch`(new_epoch)	Change the epoch for this binary model.
`check_required_params`(required_params)
`d_binary_delay_d_xxxx`(toas, param, acc_delay)	Return the binary model delay derivatives.
`get_params_of_type`(param_type)	Get all the parameters in timing model for one specific type.
`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.
`pb`([t])	Return binary period and uncertainty (optionally evaluated at different times) regardless of binary 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.
`remove_param`(param)	Remove a parameter from the Component.
`set_special_params`(spcl_params)
`setup`()	Finalize construction loaded values.
`update_binary_object`(toas[, acc_delay])	Update stand alone binary's parameters and toas from PINT-facing object.
`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`

setup()[source]: Finalize construction loaded values.

validate()[source]: Validate loaded values.

apply_units()[source]: Apply units to parameter value.

update_binary_object(toas, acc_delay=None)[source]

Update stand alone binary’s parameters and toas from PINT-facing object.

This function passes the PINT-facing object’s parameter values and TOAs to the stand-alone binary object. If the TOAs are not provided, it only updates the parameters not the TOAs.

Parameters:

toas (pint.toa.TOAs) – The TOAs that need to pass to the stand alone model.Default value is None. If toas is None, this function only updates the parameter value. If ‘acc_delay’ is not provided, the stand alone binary receives the standard barycentered TOAs.
acc_delay (numpy.ndarray) – If provided, TOAs will be corrected by provided acc_delay instead of the standard barycentering. The stand alone binary receives the input TOAs - acc_delay.

Notes

The values for obs_pos (the observatory position wrt the Solar System Barycenter) and psr_pos (the pulsar position wrt the Solar System Barycenter) are both computed in the same reference frame, ICRS or ECL depending on the model.

Warns:

If passing ‘None’ to ‘toa’ argument, the stand alone binary model will use
the TOAs were passed to it from last iteration (i.e. last barycentered
TOAs) or no TOAs for stand alone binary model at all. This behavior will
cause incorrect answers. Allowing the passing None to ‘toa’ argument is
for some lower level functions and tests. We do not recommend PINT
user to use it.

binarymodel_delay(toas, acc_delay=None)[source]: Return the binary model independent delay call.

d_binary_delay_d_xxxx(toas, param, acc_delay)[source]: Return the binary model delay derivatives.

print_par(format='pint')[source]

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

change_binary_epoch(new_epoch)[source]

Change the epoch for this binary model.

T0 will be changed to the periapsis time closest to the supplied epoch, and the argument of periapsis (OM), eccentricity (ECC), and projected semi-major axis (A1 or X) will be updated according to the specified OMDOT, EDOT, and A1DOT or XDOT, if present.

Note that derivatives of binary orbital frequency higher than the first (FB2, FB3, etc.) are ignored in computing the new T0, even if present in the model. If high-precision results are necessary, especially for models containing higher derivatives of orbital frequency, consider re-fitting the model to a set of TOAs. The use of pint.simulation.make_fake_toas() and the pint.fitter.Fitter option track_mode="use_pulse_number" can make this extremely simple.

Parameters:: new_epoch (float MJD (in TDB) or astropy.Time object) – The new epoch value.

pb(t=None)[source]

Return binary period and uncertainty (optionally evaluated at different times) regardless of binary model

Parameters:

t (astropy.time.Time, astropy.units.Quantity, numpy.ndarray, float, int, str, optional) – Time(s) to evaluate period

Returns:

astropy.units.Quantity – Binary period
astropy.units.Quantity – Binary period uncertainty

add_param(param, deriv_func=None, setup=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

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.

property free_params_component

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): Get all the parameters in timing model for one specific type.

get_prefix_mapping_component(prefix)

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)

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)

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(): Print help lines for all available parameters in model.

register_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)

Remove a parameter from the Component.

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

validate_toas(toas): Check that this model component has TOAs where needed.