LALSimIMRNRHybSur3dq8.h File Reference

C code for NRHybSur3dq8 waveform model, an NR-hybrid surrogate model for aligned-spin BBH. More...

Prototypes
static bool	NRHybSur3dq8_IsSetup (void)
static void	NRHybSur3dq8_Init_LALDATA (void)
int	NRHybSur3dq8_fitParams (gsl_vector *fit_params, const REAL8 q, const REAL8 chi1z, const REAL8 chi2z)
	Map from mass ratio and spins to surrogate fit parameters. More...
int	NRHybSur3dq8_core (gsl_vector **phi_22, EvaluatedDataPieces **evaluated_mode_dps, LIGOTimeGPS *epoch, const REAL8 deltaTOverM, const REAL8 fMin, const REAL8 fRef, REAL8 q, const REAL8 Mtot_sec, REAL8 chi1z, REAL8 chi2z, LALValue *ModeArray, LALDict *LALparams)
	This is the core function of the NRHybSur3dq8 model. More...

Detailed Description

C code for NRHybSur3dq8 waveform model, an NR-hybrid surrogate model for aligned-spin BBH.

Author

Vijay Varma

The binary data file is available at https://dcc.ligo.org/LIGO-T1900034. Get the lalsuite-extra repo or put the data into a location in your LAL_DATA_PATH.

Paper: https://arxiv.org/abs/1812.07865

Parameter ranges:

q = [1, 10.1] and \(\chi_{1z}, \chi_{2z}\) = [-0.81, 0.81] or q = [1, 9.1] and \(\chi_{1z}, \chi_{2z}\) = [-0.91, 0.91]

modes: \( \ell \leq 4, m \geq 0 \), and (5,5), but not (4,1) or (4,0). m<0 modes are determined from the m \(\geq0\) modes.

\(M \geq 2.25 M_{\odot} \), for fstart=20Hz, for all modes.

Training parameter ranges:

q = [1, 8]

\(\chi_{1z}, \chi_{2z}\) = [-0.8, 0.8]

But extrapolates reasonably to the above mass ratios and spins.

Definition in file LALSimIMRNRHybSur3dq8.h.

Go to the source code of this file.

Variables
static const char	NRHybSur3dq8_DATAFILE [] = "NRHybSur3dq8_lal.h5"

Function Documentation

NRHybSur3dq8_IsSetup()

static bool NRHybSur3dq8_IsSetup ( void  )

static

NRHybSur3dq8_Init_LALDATA()

static void NRHybSur3dq8_Init_LALDATA ( void  )

static

NRHybSur3dq8_fitParams()

int NRHybSur3dq8_fitParams	(	gsl_vector *	fit_params,
		const REAL8	q,
		const REAL8	chi1z,
		const REAL8	chi2z
	)

Map from mass ratio and spins to surrogate fit parameters.

The fit parameters are \([log_e(q), \hat{\chi}, \chi_a]\). \(\hat{\chi}\) is defined in Eq.(46) of arxiv:1812.07865. \(\chi_a = (\chi_{1z} - \chi_{2z})/2 \). These are described in Sec.VI.C.3 of arxiv:1812.07865.

Parameters

fit_params	Output: mapped fit parameters.
q	Mass ratio m1 / m2 >= 1.
chi1z	Dimless spin of heavier BH.
chi2z	Dimless spin of lighter BH.

Definition at line 155 of file LALSimIMRNRHybSur3dq8.c.

NRHybSur3dq8_core()

int NRHybSur3dq8_core	(	gsl_vector **	phi_22,
		EvaluatedDataPieces **	evaluated_mode_dps,
		LIGOTimeGPS *	epoch,
		const REAL8	deltaT,
		const REAL8	fMin,
		const REAL8	fRef,
		REAL8	q,
		const REAL8	Mtot_sec,
		REAL8	chi1z,
		REAL8	chi2z,
		LALValue *	ModeArray,
		LALDict *	LALparams
	)

This is the core function of the NRHybSur3dq8 model.

It evaluates all required waveform modes. For each mode, it evaluates each waveform data piece. The different data pieces are described in Sec.VI.B of arxiv:1812.07865. For the (2,2) mode the data pieces are the amplitude and phase. Note that we model the phase residual but add back the 0PN term at evaluation time. For all other modes the data pieces are the real and imaginary parts of the strain in the coorbital frame.

The reference point is the time at which the (2,2) mode frequency equals fRef. If fRef=0, sets fRef=fMin. We set the orbital phase to 0 at the reference point. The orbital phase is obtained as \(\phi_{22}/2\), so this leaves a pi ambiguity. But the surrogate data is already aligned such that the heavier BH is on the +ve x-axis at t=-1000M. See Sec.VI.A.4 of arxiv:1812.07865. This resolves the pi ambiguity. This means that after the realignment, the orbital phase at reference frequency fRef is 0, or Bh1 is on the +ve x-axis. Note that this is alignment is done using only waveform quantities, so this doesn't necessarily correspond to the (gauge dependent) NR Bh trajectories. The modes are returned in this frame, which agrees with the LAL convention. When combining the modes to get the polarizations, the Ylms should be evaluated at (inclination, pi/2 - phiRef), following the LAL convention.

Only uses data at (2,2) mode frequencies >= fMin. This determines the start time. The start time, along with the step size deltaT, is used to determine the output_times. Uses cubic spline interpolation to interpolate from the surrogate's time array to output_times.

NOTE: If mass ratio q<1, the labels of the two BHs are swapped internally.

Returned values:

phi_22: contains the phase of the (2,2) mode. This is always evaluated as this is required for other modes as well to transform from coorbital frame to inertial frame.

evaluated_mode_dps: Contains all other data pieces. This is a list of size num_modes_incl, the number of modes to include. For each mode this contains the amplitude, and real and imaginary parts of the coorbital frame strain. For the (2,2) mode only the amplitude is required. For all other modes only the coorbital frame strain is required. So, we evaluate only the required data pieces of each mode. The amplitude and coorbital frame strain is in units of rh/M and needs to be rescaled to physical units.

epoch: Initial time value, w.r.t. the peak (t=0 at the peak) of the total waveform amplitude, as defined in Eq.38 of arxiv:1812.07865.

Parameters

phi_22	Output: phase of (2,2) mode.
evaluated_mode_dps	Output: All other data pieces.
epoch	Output: Initial time value, where t=0 is at the peak of the total waveform amplitude.
deltaT	Sampling interval (s).
fMin	Start GW frequency (Hz).
fRef	Reference GW frequency (Hz).
q	Mass ratio m1/m2.
Mtot_sec	Total mass in geometric units (s).
chi1z	Dimensionless spin of Bh1.
chi2z	Dimensionless spin of Bh2.
ModeArray	Container for (ell, m) modes to generate.
LALparams	Dict with extra parameters

Definition at line 230 of file LALSimIMRNRHybSur3dq8.c.

Variable Documentation

NRHybSur3dq8_DATAFILE

const char NRHybSur3dq8_DATAFILE[] = "NRHybSur3dq8_lal.h5"

static

Definition at line 73 of file LALSimIMRNRHybSur3dq8.h.