Spectral separation of the stochastic gravitational-wave background for LISA: Observing both cosmological and astrophysical backgrounds
Résumé
With the goal of observing a stochastic gravitational-wave background (SGWB) with LISA, the spectral separability of the cosmological and astrophysical backgrounds is important to estimate. We attempt to determine the level with which a cosmological background can be observed given the predicted astrophysical background level. We predict detectable limits for the future LISA measurement of the SGWB. Adaptive Markov chain Monte Carlo methods are used to produce estimates with the simulated data from the LISA Data Challenge. We also calculate the Cramer-Rao lower bound on the variance of the SGWB parameter estimates based on the inverse Fisher information using the Whittle likelihood. The estimation of the parameters is done with the three LISA channels A, E, and T. We simultaneously estimate the noise using a LISA noise model. Assuming the expected astrophysical background around ΩGW,astro(25 Hz)=0.355→35.5×10-9, a cosmological SGWB normalized energy density of around ΩGW,Cosmo≈1×10-12 to 1×10-13 can be detected by LISA after 4 years of observation.
Mots clés
Cosmology
gravitational radiation: background
gravitational radiation: stochastic
Monte Carlo: Markov chain
cosmological model
LISA
energy: density
detector: noise
LIGO
noise
covariance
VIRGO
statistical analysis: Bayesian
black hole: binary
binary: coalescence
gravitational radiation: emission
neutron star: binary
binary: compact
data analysis method
background: stochastic
gravitational radiation detector
detector: sensitivity
white dwarf: binary
cosmic string
time delay: interferometer
numerical methods
numerical calculations
inflation