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Spin-Orbit Misalignment in Binary Black Holes from Triple-Star Common Envelope Evolution: A Semi-Analytical Rate Estimate

TYPEStudent Seminar
Speaker:Lotem Unger
Date:06.05.2026
Time:11:30 - 12:30
Location:Lidow 620
Abstract:

Gravitational-wave observations reveal that the effective inspiral spin distribution of merging binary black holes is asymmetric about zero, with a significant fraction of negative values. We investigate the plausibility of a triple-star formation channel, within the jittering jets explosion mechanism framework, in which two episodes of common envelope evolution naturally produce spin-orbit misalignment. Using empirically calibrated initial distributions for massive stars, we compute the probability that a zero-age main-sequence system has parameters consistent with this channel and calibrate against observed core-collapse supernova and merger rates. We assess both binary and triple progenitor configurations and examine how the additional requirements of the triple channel — a second companion in a specific mass and period range, and dynamical stability — shape the expected contribution of this pathway to the overall merger rate. We discuss the implications of our results for the role of triple-star systems in the observed population of merging binary black holes.