Cosmic string gravitational wave backgrounds at LISA: II. Reconstruction of conventional signals over astrophysical foregrounds
arXiv:2607.15219
The paper investigates how well LISA can recover a stochastic gravitational‑wave background from cosmic strings when realistic astrophysical foregrounds are present, using the GWBackFinder simulation‑based inference framework, and finds that detectable string tensions must be roughly 10⁻¹¹ or larger.
Abstract
We study the reconstruction of conventional cosmic-string signals with LISA in the presence of all major known astrophysical foregrounds expected in the LISA band. These include stellar-origin black-hole binaries (SOBHBs), galactic (WDs) and extragalactic (ExWDs) white dwarfs, extreme-mass-ratio-inspirals (EMRIs), and massive black-hole binaries (MBHBs). Using the Simulation-based Inference package GWBackFinder, we perform a joint inference on the LISA noise, foregrounds, and signal, across a range of injected string tensions . We find that reconstructing tensions with an error requires values as large as , i.e. a factor larger than previous estimates with no foregrounds, and larger compared to estimates accounting only for SOBHB and WD foregrounds. This work is the second in a series initiated in Ref. arXiv:2508.05395, which aims to quantify LISA's ability to measure representative cosmic-string models.
19 pages + 8 figures