English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Accretion discs in active galactic nuclei (AGN) foster black hole (BH)formation, growth, and mergers. Stellar mass BHs migrate inwards under theinfluence of hydrodynamical torques unless they encounter a region where thetorque flips sign. At these migration traps, BHs accumulate and merge viadynamical or gas-assisted interactions, producing high-frequencyLIGO/Virgo/KAGRA (LVK) gravitational wave (GW) sources and potentially cuttingoff the supply of extreme mass ratio inspirals that would otherwise makelow-frequency, {\it LISA}-band GWs. In this paper, we study the interplaybetween different types of migration torques, focusing especially on the``thermal torques'' generated by the thermal response of the AGN to embeddedstellar-mass BHs that accrete through their own mini-discs.In contrast toprevious work, we find that Type I torques cannot produce migration traps ontheir own, but thermal torques often do, particularly in low-mass AGN. Themigration traps produced by thermal torques exist at much larger radii ($\sim10^{3-5}$ gravitational radii) than do previously identified Type I traps,carrying implications for GW populations at multiple frequencies. Finally, weidentify a bifurcation of AGN discs into two regimes: migration traps existbelow a critical AGN luminosity, and do not at higher luminosities. Thiscritical luminosity is fit as $\log_{10} L_{\rm AGN}^c = 45 - 0.32\log_{10}{(\alpha/0.01)}$ where $\alpha$ is the AGN alpha viscosity parameter,a range compatible with recent claims that LVK GWs are not preferentiallyassociated with high-luminosity AGN.

The Effect of Thermal Torques on AGN Disc Migration Traps and Gravitational Wave Populations