Spacetime¶

Instances of Spacetime are ambient Schwarzschild spacetimes in which photospheres are embedded.

class xpsi.Spacetime.Spacetime(bounds, values)[source]

The ambient Schwarzschild spacetime and Earth coordinates.

Parameters: bounds (dict) – Tuples of hard bounds on parameters with keys matching the names in the initialiser body. A None bound will be interpreted as fixed variable, in which case a value must be supplied in the corresponding dictionary. If there is no entry for a default parameter, it will be assumed to be fixed, but an exception will be raised if there is no associated value. values (dict) – Values of fixed parameters or initial values for free parameters, with keys matching the names in the initialiser body. If there is no entry for a default parameter, no initial value will be specified, but an exception will be raised if there is also no bound specified.

We define a property for parameters and combinations of parameters to shortcut access, given that this subspace is passed to other subspaces for model computation. We would like to access the values with fewer characters than self[<name>].

Required parameter names:
• frequency
• mass
• distance
• cos_inclination
M

Get the (rotationally deformed) gravitational mass in SI.

Omega

Get the coordinate angular rotation frequency.

R

Get the coordinate equatorial radius in SI.

R_r_s

d

Get the distance of the Earth to the star in SI.

d_sq

Get the squared distance of the Earth to the star in SI.

epsilon

Get the derived parameter epsilon for universal relations.

A dimensionless function of stellar properties.

See Morsink et al. (2007), and AlGendy & Morsink (2014).

f

Get the coordinate rotation frequency.

classmethod fixed_spin(frequency)[source]
Parameters: frequency (float) – The fixed coordinate spin frequency in Hz.

Note

The degeneracy due to equatorially-reflection symmetric physics is eliminated here by declaring prior support for Earth inclination from northern rotation pole to equatorial plane.

i

Get the inclination of the Earth to the rotational axis.

r_g

Get the Schwarzschild gravitational radius in SI.

r_s

Get the Schwarzschild radius in SI.

zeta

Get the derived parameter zeta for universal relations.

A dimensionless function of stellar properties.

See Morsink et al. (2007), and AlGendy & Morsink (2014).