Detailed Description

Functions to transform waveform parameters between LALSimulation and LALInference coordinate conventions.

Author: Riccardo Sturani

Prototypes
int	XLALSimInspiralTransformPrecessingNewInitialConditions (REAL8 incl, REAL8 S1x, REAL8 S1y, REAL8 S1z, REAL8 S2x, REAL8 S2y, REAL8 *S2z, const REAL8 thetaJN, const REAL8 phiJL, const REAL8 theta1, const REAL8 theta2, const REAL8 phi12, const REAL8 chi1, const REAL8 chi2, const REAL8 m1_SI, const REAL8 m2_SI, const REAL8 fRef, const REAL8 phiRef)
	Transform Precessing Parameters. More...

int	XLALSimInspiralTransformPrecessingWvf2PE (REAL8 thetaJN, REAL8 phiJL, REAL8 theta1, REAL8 theta2, REAL8 phi12, REAL8 chi1, REAL8 *chi2, const REAL8 incl, const REAL8 S1x, const REAL8 S1y, const REAL8 S1z, const REAL8 S2x, const REAL8 S2y, const REAL8 S2z, const REAL8 m1, const REAL8 m2, const REAL8 fRef, const REAL8 phiRef)
	inverse to XLALSimInspiralTransformPrecessingNewInitialConditions() More...

Function Documentation

◆ XLALSimInspiralTransformPrecessingNewInitialConditions()

int XLALSimInspiralTransformPrecessingNewInitialConditions	(	REAL8 *	incl,
		REAL8 *	S1x,
		REAL8 *	S1y,
		REAL8 *	S1z,
		REAL8 *	S2x,
		REAL8 *	S2y,
		REAL8 *	S2z,
		const REAL8	thetaJN,
		const REAL8	phiJL,
		const REAL8	theta1,
		const REAL8	theta2,
		const REAL8	phi12,
		const REAL8	chi1,
		const REAL8	chi2,
		const REAL8	m1_SI,
		const REAL8	m2_SI,
		const REAL8	fRef,
		const REAL8	phiRef
	)

Transform Precessing Parameters.

Routine for transforming LALInference geometric variables to ChooseWaveform input

Function to specify the desired orientation of a precessing binary in terms of several angles and then compute the vector components with respect to orbital angular momentum as needed to specify binary configuration for ChooseTDWaveform.

Representation of input variables.

Input:

thetaJN is the inclination between total angular momentum (J) and the direction of propagation (N=(0,sin(thetaJN),cos(thetaJN)))
Note
This choice has been made to made so that thetaJN -> inclination for \( S_{1}+S_{2} \to 0\).
theta1 and theta2 are the inclinations of \(S_{1,2}\) measured from the Newtonian orbital angular momentum ( \(L_{N}\)).
phi12 is the difference in azimuthal angles of \(S_{1,2}\).
chi1, chi2 are the dimensionless spin magnitudes ( chi1, chi2 \(\le 1\))
phiJL is the azimuthal angle of \(L_{N}\) on its cone about J.
m1, m2, f_ref, phiref are the component masses and reference GW frequency and orbital phase, they are needed to compute the magnitude of \(L_{N}\), and thus J.

Output:

incl - inclination angle of N relative to L_N (N=(0,sin(incl),cos(incl))) in the p-q-Z frame. x, y, z components \(S_{1,2}\) (unit spin vectors times their dimensionless spin magnitudes - i.e. they have unit magnitude for extremal BHs and smaller magnitude for slower spins). where x-y are rotated by phiRef with respect to p-q, i.e. is \(S_{1}\) wrt to x-y is (a,b,0), wrt to p-q will be (a cos(phiRef) + b sin (phiRef), )

Note: Here the "total" angular momentum is computed as J = \(L_{N}(1+l_{1PN}) + S_{1} + S_{2}\) where \(L_N\) is the Newtonian orbital angular momentum and \(l_{1PN}\) its relative 1PN corrections. In fact, there are PN corrections to L which contribute to J that are NOT ACCOUNTED FOR in this function. This is done so to avoid complications with spin-orbit contributions to L, which would require the full knowledge fo the orbital motion, not just the evolution of L (see e.g. eq.2.9c of arXiv:gr-qc/9506022). Also, it is believed that the difference in Jhat with or without these PN corrections to L is quite small.

Attention: fRef = 0 is not a valid choice. If you will pass fRef=0 into ChooseWaveform, then here pass in f_min, the starting GW frequency

UNREVIEWED

Parameters

incl	Inclination angle of L_N (returned)
S1x	S1 x component (returned)
S1y	S1 y component (returned)
S1z	S1 z component (returned)
S2x	S2 x component (returned)
S2y	S2 y component (returned)
S2z	S2 z component (returned)
thetaJN	zenith angle between J and N (rad)
phiJL	azimuthal angle of L_N on its cone about J (rad)
theta1	zenith angle between S1 and LNhat (rad)
theta2	zenith angle between S2 and LNhat (rad)
phi12	difference in azimuthal angle btwn S1, S2 (rad)
chi1	dimensionless spin of body 1
chi2	dimensionless spin of body 2
m1_SI	mass of body 1 (kg)
m2_SI	mass of body 2 (kg)
fRef	reference GW frequency (Hz)
phiRef	reference orbital phase

Definition at line 3587 of file LALSimInspiral.c.

◆ XLALSimInspiralTransformPrecessingWvf2PE()

int XLALSimInspiralTransformPrecessingWvf2PE	(	REAL8 *	thetaJN,
		REAL8 *	phiJL,
		REAL8 *	theta1,
		REAL8 *	theta2,
		REAL8 *	phi12,
		REAL8 *	chi1,
		REAL8 *	chi2,
		const REAL8	incl,
		const REAL8	S1x,
		const REAL8	S1y,
		const REAL8	S1z,
		const REAL8	S2x,
		const REAL8	S2y,
		const REAL8	S2z,
		const REAL8	m1,
		const REAL8	m2,
		const REAL8	fRef,
		const REAL8	phiRef
	)

inverse to XLALSimInspiralTransformPrecessingNewInitialConditions()

This function performs inverse transformation to XLALSimInspiralTransformPrecessingNewInitialConditions() it takes as input waveform parameters, assume to be defined in the L=z, n=x (L-robital momentum at fRef, n is orbital separation at fRef. Direction of propagation (direction to the observer) N is defined by spherical angles (pi/2-phiRef, inclination). The return parameters are what is used in PE for sampling (see description in ....) Note that the masses are in solar mass and |L| is computed to the same order as in the direct function above. Spins are dimensionless.