README File for Simulation of Galactic White Dwarf Binary Background.

Matthew Benacquista, Donald Lunder, and John De Goes

March 10, 2004



Source Information
====================

9.0e4 Close White Dwarf Binaries 

The sources were drawn from the distribution described in

M. Benacquista, J. DeGoes, and D. Lunder, Class. Quant. Grav., 21, S509 (2004).

The population has been artificially cut off at orbital periods above 2000 s
corresponding to gravitational wave frequency of 1 mHz. The number of sources
has been chosen to approximately match the number of CWDB in the relevant 
frequency band as described in

D. Hils, P. Bender, and R.F. Webbink, Astrophys. J., 360, 75 (1990).

We have reduced the number by the same factor of 10 as Hils, et al.

The source parameters for the entire population are recorded in the file
"Parameters.dat". The file is organized by increasing orbital period. Each
row represents one binary and the nine columns list the following parameters.
The masses of the first (M_1) and second (M_2) white dwarf formed in the 
system in solar masses. The orbital period (P_orb) of the systems in seconds. The distance (d) in kpc from the sun to the binary. The angular position 
(theta_s) and (phi_s) of the binary in polar ecliptic coordinates. The 
orientation of the angular momentum vector of the binary (theta_l) and 
(phi_l) in the same coordinate system. The relative orbital phase (phi_o)
of the binary.

The position and orientation parameters are described in Benacquista, et al.


Detector Information
====================

The simulation is based on the low frequency approximation described in

C. Cutler, Phys. Rev. D, 57, 7089 (1998)

using phibar = 0 and alpha_o =0. These correspond to the following LISA
Simulator parameters:

Total Observation Time = 3.2e7 seconds
Number of sample points: 3.2e7
Sample Cadence: 1 second
kappa: 0
lambda: 3 pi/4

All binaries are assumed to be monochromatic (an assumption that breaks down 
for some of the highest frequency sources in the simulation). If desired, 
these sources can be subtracted from the simulation.

The connection between the LISA Simulator output and Curt Cutler's low 
frequency approximation is described in

N.J. Cornish and L.J. Rubbo, Phys. Rev. D, 67, 022001 (2003).

Simulated Data Information
==========================

The simulated response to the Galactic population of close white dwarf 
binaries can be found in the file "h1sum90k.dat". This file lists one 
column of the strain amplitude h_I calculated from Cutler (1998). Details
of the computation can be found in Benacquista et al. (2004). This 
simulation can be combined with other LISA Simulator data if the 
prescription found in Cornish and Rubbo (2003) is used to combine the
TDI variables X, Y, and Z to generate h_I.