Year: 2026
Type: article
Abstract: High-redshift massive black-hole binary (MBHB) mergers provide a probe of black-hole seed formation and early galaxy assembly, but the population detected by LISA can be modified by galaxy-scale strong lensing. We quantify this effect for MBHB mergers at 10≤z≤20 and assess its impact on intrinsic formation-channel fractions. We use four light- and heavy-seed channels with delayed and non-delayed mergers, and compute 4-year LISA-detectable event numbers with and without strong lensing. The lens population follows an evolving velocity-dispersion-function prescription. We consider a reference mixture with equal catalogue mixture coefficients and additional mixtures with selected catalogue coefficients increased. Strong lensing can change the detected channel mixture and total number of detections unequally. For the adopted lens population, the total correction is small in the reference mixture, although the channel dependence can be appreciable for LS-nod. Conditional analyses using lensing-aware and lensing-ignored templates give broadly similar formation-fraction posteriors across the tested mixtures, while the heavy-seed delay fraction remains poorly constrained because its detectable contribution is small. For the adopted lens population, the shift induced by neglecting strong lensing remains smaller than the statistical formation-fraction uncertainty in the conditional analyses considered here.
Authors: yanheng jin, Wenbiao Han
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7167578652
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