pint.models.binary_bt.BinaryBT
- class pint.models.binary_bt.BinaryBT[source]
Bases:
PulsarBinary
Blandford and Teukolsky binary model.
This binary model is described in Blandford and Teukolshy 1976. It is a relatively simple parametrized post-Keplerian model that does not support Shapiro delay calculations.
The actual calculations for this are done in
pint.models.stand_alone_psr_binaries.BT_model.BTmodel
.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
FB{number}
0th time derivative of frequency of orbit
1 / s
GAMMA
Time dilation & gravitational redshift
s
Notes
Because PINT’s binary models all support specification of multiple orbital frequency derivatives FBn, this is capable of behaving like the model called BTX in tempo2. The model called BTX in tempo instead supports multiple (non-interacting) companions, and that is not supported here. Neither can PINT accept “BTX” as an alias for this model.
See Blandford & Teukolsky 1976, ApJ, 205, 580.
Methods
FBX_description
(n)FBX_unit
(n)add_param
(param[, deriv_func, setup])Add a parameter to the Component.
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.
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 BT model parameters
validate_toas
(toas)Check that this model component has TOAs where needed.
Attributes
Return all the aliases and map to the PINT parameter name.
category
component_types
Return the free parameters in the component.
param_prefixs
register
- 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.
- apply_units()
Apply units to parameter value.
- binarymodel_delay(toas, acc_delay=None)
Return the binary model independent delay call.
- change_binary_epoch(new_epoch)
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 thepint.fitter.Fitter
optiontrack_mode="use_pulse_number"
can make this extremely simple.- Parameters:
new_epoch (float MJD (in TDB) or astropy.Time object) – The new epoch value.
- d_binary_delay_d_xxxx(toas, param, acc_delay)
Return the binary model delay derivatives.
- 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.
- 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:
- 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.
- pb(t=None)
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
- print_par(format='pint')
- 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, 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.
- setup()
Finalize construction loaded values.
- update_binary_object(toas, acc_delay=None)
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) andpsr_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.
- validate_toas(toas)
Check that this model component has TOAs where needed.