Ability of LISA to detect a gravitational-wave background of cosmological origin: the cosmic string case

Understand

We investigate the ability of the Laser Interferometer Space Antenna (LISA) to detect a stochastic gravitational-wave background (GWB) produced by cosmic strings, and to subsequently estimate the string tension $G\mu$ in the presence of instrument noise, an astrophysical background from compact binaries, and the galactic foreground from white dwarf binaries.

• Fisher Information and Markov Chain Monte Carlo methods provide estimates of the LISA noise and the parameters for the different signal sources.
• We demonstrate the ability of LISA to simultaneously estimate the galactic foreground, as well as the astrophysical and cosmic string produced backgrounds.
• Considering the expected astrophysical background and a galactic foreground, a cosmic string tension in the $G \mu \approx 10^{-16}$ to $G\mu \approx 10^{-15}$ range or bigger could be measured by LISA, with the galactic foreground affecting this limit more than the astrophysical background.