The Binary Black Hole Merger Rate Deviates From the Cosmic Star Formation Rate: A Tug of War Between Metallicity and Delay Times
arxiv(2024)
摘要
Gravitational-wave detectors are now making it possible to investigate how
the merger rate of binary black holes (BBHs) evolves with redshift. In this
study, we examine whether the BBH merger rate of isolated binaries deviates
from a scaled star formation rate density (SFRD) – a frequently used model in
state-of-the-art research. To address this question, we conduct population
synthesis simulations using COMPAS with a grid of stellar evolution models,
calculate their cosmological merger rates, and compare them to a scaled SFRD.
We find that our simulated rates deviate by factors up to 3.5× at
z∼0 and 5× at z∼ 9 due to two main phenomena: (i) The
formation efficiency of BBHs is an order of magnitude higher at low
metallicities than at solar metallicity; and (ii) BBHs experience a wide range
of delays (from a few Myr to many Gyr) between formation and merger. Deviations
are similar when comparing to a delayed SFRD, and even larger (up to
∼ 10×) when comparing to SFRD-based models scaled to the local merger
rate. Interestingly, our simulations find that the BBH delay time distribution
is redshift-dependent, increasing the complexity of the redshift distribution
of mergers. We find similar results for simulated merger rates of BHNSs and
BNSs. We conclude that the rate of BBH, BHNS, and BNS mergers from the isolated
channel can significantly deviate from a scaled SFRD, and that future
measurements of the merger rate will provide insights into the formation
pathways of gravitational-wave sources.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要