Help on NRHybSur3dq8 in module gwsurrogate.surrogate object:
class NRHybSur3dq8(SurrogateEvaluator)
| A class for the NRHybSur3dq8 surrogate model presented in Varma et al. 2018,
| arxiv:1812.07865.
|
| Evaluates gravitational waveforms generated by aligned-spin binary black hole
| systems. This model was built using numerical relativity (NR) waveforms that
| have been hybridized using post-Newtonian (PN) and effective one body (EOB)
| waveforms.
|
| This model includes the following spin-weighted spherical harmonic modes:
| (2,2), (2,1), (2,0), (3,3), (3,2), (3,1), (3,0), (4,4) (4,3), (4,2) and (5,5).
| The m<0 modes are deduced from the m>0 modes.
|
| The parameter space of validity is:
| q \in [1, 10] and chi1z/chi2z \in [-1, 1],
| where q is the mass ratio and chi1z/chi2z are the spins of the heavier/lighter
| BH, respectively, in the direction of orbital angular momentum.
|
| The surrogate has been trained in the range
| q \in [1, 8] and chi1z/chi2z \in [-0.8, 0.8], but produces reasonable waveforms
| in the above range and has been tested against existing NR waveforms in that
| range.
|
| See the __call__ method on how to evaluate waveforms.
| In the __call__ method, x must have format x = [q, chi1z, chi2z].
|
| Method resolution order:
| NRHybSur3dq8
| SurrogateEvaluator
| __builtin__.object
|
| Methods defined here:
|
| __init__(self, h5filename)
|
| ----------------------------------------------------------------------
| Methods inherited from SurrogateEvaluator:
|
| __call__(self, q, chiA0, chiB0, M=None, dist_mpc=None, f_low=None, f_ref=None, dt=None, df=None, times=None, freqs=None, mode_list=None, ellMax=None, inclination=None, phi_ref=0, precessing_opts=None, tidal_opts=None, par_dict=None, units='dimensionless', skip_param_checks=False, taper_end_duration=None)
| INPUT
| =====
| q : Mass ratio, mA/mB >= 1.
| chiA0: Dimensionless spin vector of the heavier black hole at
| reference epoch.
| chiB0: Dimensionless spin vector of the lighter black hole at
| reference epoch.
|
| This follows the same convention as LAL, where the spin
| components are defined as:
| \chi_z = \chi \cdot \hat{L}, where L is the orbital angular
| momentum vector at the epoch.
| \chi_x = \chi \cdot \hat{n}, where n = body2 -> body1 is the
| separation vector at the epoch. body1 is the heavier body.
| \chi_y = \chi \cdot \hat{L \cross n}.
| These spin components are frame-independent as they are
| defined using vector inner products. This is equivalent to
| specifying the spins in the coorbital frame used in the
| surrogate papers.
|
| M, dist_mpc: Either specify both M and dist_mpc or neither.
| M : Total mass (solar masses). Default: None.
| dist_mpc : Distance to binary system (MegaParsecs). Default: None.
|
| f_low : Instantaneous initial frequency of the (2, 2) mode. In
| practice, this is estimated to be twice the initial orbital
| frequency in the coprecessing frame. Note: the coprecessing
| frame is the minimal rotation frame of arXiv:1110.2965.
|
| f_low should be in cycles/M if units = 'dimensionless',
| should be in Hertz if units = 'mks'.
| If 0, the entire waveform is returned.
| Default: None, must be specified by user.
|
| NOTE: For some models like NRSur7dq4, f_low=0 is recommended.
| The role of f_low is only to truncate the lower frequencies
| before returning the waveform. Since this model is already
| very short, this truncation is not required. On the other hand,
| f_ref is used to set the reference epoch, and can be freely
| specified.
|
| WARNING: Using f_low=0 with a small dt (like 0.1M) can lead to
| very expensive evaluation for hybridized surrogates like
| NRHybSur3dq8.
|
| f_ref: Frequency used to set the reference epoch at which the
| reference frame is defined and the spins are specified.
| See below for definition of the reference frame.
| Should be in cycles/M if units = 'dimensionless', should be
| in Hertz if units = 'mks'.
| Default: If f_ref is not given, we set f_ref = f_low. If
| f_low is 0, this corresponds to the initial index.
|
| For time domain models, f_ref is used to determine a t_ref,
| such that the orbital frequency in the coprecessing frame
| equals f_ref/2 at t=t_ref.
|
| dt, df : Time/Frequency step size, specify at most one of dt/df,
| depending on whether the surrogate is a time/frequency domain
| surrogate.
| Default: None. If None, the internal domain of the surrogate is
| used, which can be nonuniformly sampled.
| dt (df) Should be in M (cycles/M) if units = 'dimensionless',
| should be in seconds (Hertz) if units = 'mks'. Do not specify
| times/freqs if using dt/df.
|
|
| times, freqs:
| Array of time/frequency samples at which to evaluate the
| waveform, depending on whether the surrogate is a
| time/frequency domain surrogate. time (freqs) should be in
| M (cycles/M) if units = 'dimensionless', should be in
| seconds (Hertz) if units = 'mks'. Do not specify dt/df if
| using times/freqs. Default None.
|
| ellMax: Maximum ell index for modes to include. All available m
| indicies for each ell will be included automatically.
| Default: None, in which case all available modes wll be
| included.
|
| mode_list : A list of (ell, m) modes tuples to be included.
| Example: mode_list = [(2,2),(2,1)].
| Default: None, in which case all available modes are included.
| The m<0 modes will automatically be included for nonprecessing
| models. At most one of ellMax and mode_list can be specified.
|
| Note: mode_list is allowed only for nonprecessing models; for
| precessing models use ellMax. For precessing systems, all m
| indices of a given ell index mix with each other, so there is
| no clear hierarchy. To get the individual modes just don't
| specify inclination and a dictionary of modes will be returned.
|
| phi_ref : The angle on the plane of the orbit from the line of ascending
| nodes to the position of the body 1 at reference epoch. Can
| also be thought of as the orbital phase at reference epoch.
| Default: 0.
|
| inclination : Inclination angle between the orbital angular momentum
| direction at the reference epoch and the line-of-sight to the
| observer.
| If inclination is None, the mode data is returned as a
| dictionary.
| If specified, the complex strain (h = hplus -i hcross)
| evaluated at (inclination, pi/2) on the sky of the reference
| frame is returned. This follows the same convention as LAL,
| where the azimuthal angle is set through phi_ref. See below
| for definition of the reference frame.
| Default: None.
|
| precessing_opts:
| A dictionary containing optional parameters for a precessing
| surrogate model. Default: None.
| Allowed keys are:
| quat_ref: The unit quaternion (length 4 vector) giving the
| rotation from the coprecessing frame to the inertial frame
| at the reference epoch.
| Default: None, in which case the spins in the coprecessing
| frame are equal to the spins in the inertial frame.
| return_dynamics:
| Return the frame dynamics and spin evolution along with
| the waveform. Default: False.
| use_lalsimulation_conventions:
| If True, interprets the spin directions and init_orbphase
| using lalsimulation conventions. Specifically, before
| evaluating the surrogate, the spins will be rotated about
| the z-axis by init_phase. Default: True (see
| DynamicsSurrogate, which is the only place this option is
| used).
| Example: precessing_opts = {
| 'quat_ref': [1,0,0,0],
| 'return_dynamics': True
| }
|
| tidal_opts:
| A dictionary containing optional parameters for a tidal
| surrogate model. Default: None.
| Allowed keys are:
| Lambda1: The tidal deformability parameter for the heavier
| object.
| Lambda2: The tidal deformability parameter for the lighter
| object.
| Example: tidal_opts = {'Lambda1': 200, 'Lambda2': 300}
|
|
| par_dict: A dictionary containing any additional parameters needed for a
| particular surrogate model. Default: None.
|
| units: 'dimensionless' or 'mks'. Default: 'dimensionless'.
| If 'dimensionless': Any of f_low, f_ref, dt, df, times and
| freqs, if specified, must be in dimensionless units. That
| is, dt/times should be in units of M, while f_ref, f_low
| and df/freqs should be in units of cycles/M.
| M and dist_mpc must be None. The waveform and domain are
| returned as dimensionless quantities as well.
| If 'mks': Any of f_low, f_ref, dt, df, times and freqs, if
| specified, must be in MKS units. That is, dt/times should
| be in seconds, while f_ref, f_low and df/freqs should be
| in Hz. M and dist_mpc must be specified. The waveform and
| domain are returned in MKS units as well.
|
|
| skip_param_checks :
| Skip sanity checks for inputs. Use this if you want to
| extrapolate outside allowed range. Default: False.
|
| taper_end_durataion:
| Taper the last TAPER_END_DURATION (M) of a time-domain waveform
| in units of M. For exmple, passing 40 will taper the last 40M.
| When set to None, no taper is applied
| Default: None.
|
| RETURNS
| =====
|
| domain, h, dynamics
|
|
| domain : Array of time/frequency samples corresponding to h and
| dynamics, depending on whether the surrogate is a
| time/frequency domain model. This is the same as times/freqs
| if times/freqs are given as an inputs.
| For time domain models the time is set to 0 at the peak of
| the waveform. The time (frequency) values are in M (cycles/M)
| if units = 'dimensionless', they are in seconds (Hertz) if
| units = 'mks'
|
| h : The waveform.
| If inclination is specified, the complex strain (h = hplus
| -i hcross) evaluated at (inclination, pi/2) on the sky of
| the reference frame is returned. This follows the LAL
| convention, see below for details. This includes all modes
| given in the ellMax/mode_list argument. For nonprecessing
| systems the m<0 modes are automatically deduced from the
| m>0 modes. To see if a model is precessing check
| self.keywords.
|
| Else, h is a dictionary of available modes with (l, m)
| tuples as keys. For example, h22 = h[(2,2)].
|
| If M and dist_mpc are given, the physical waveform
| at that distance is returned. Else, it is returned in
| code units: r*h/M extrapolated to future null-infinity.
|
| dynamics: A dict containing the frame dynamics and spin evolution. This
| is None for nonprecessing models. This is also None if
| return_dynamics in precessing_opts is False (Default).
|
| The dynamics include (L=len(domain)):
|
| q_copr = dynamics['q_copr']
| The quaternion representing the coprecessing frame with
| shape (4, L)
| orbphase = dynamics['orbphase']
| The orbital phase in the coprecessing frame with length L.
| chiA = dynamics['chiA']
| The inertial frame chiA with shape (L, 3)
| chiB = dynamics['chiB']
| The inertial frame chiB with shape (L, 3)
|
|
| IMPORTANT NOTES:
| ===============
|
| The reference frame (or inertial frame) is defined as follows:
| The +ve z-axis is along the orbital angular momentum at the reference
| epoch. The orbital phase at the reference epoch is phi_ref. This means
| that the separation vector from the lighter BH to the heavier BH is at
| an azimuthal angle phi_ref from the +ve x-axis, in the orbital plane at
| the reference epoch. The y-axis completes the right-handed triad. The
| reference epoch is set using f_ref.
|
| Now, if inclination is given, the waveform is evaluated at
| (inclination, pi/2) in the reference frame. This agrees with the LAL
| convention. See LIGO DCC document T1800226 for the LAL frame diagram.
|
| ----------------------------------------------------------------------
| Data descriptors inherited from SurrogateEvaluator:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
