Routing (electronic design automation)

Stellar density

Demography

Galaxy

Astrophysics

Computer science

Intermediate-mass black hole

Computer network

Routing protocol

Elliptical galaxy

Physics

Astronomy

Link-state routing protocol

Supermassive black hole

Population

Sociology

Gravitational wave

Black hole (networking)

Globular cluster

Star cluster

Monthly Notices of the Royal Astronomical Society

We model the inspiral of globular clusters (GCs) towards a galactic nucleus harboring a supermassive black hole (SMBH), a leading scenario for the formation of nuclear star clusters.We consider the case of GCs containing either an intermediate-mass black hole (IMBH) or a population of stellar mass black holes (BHs), and study the formation of gravitational wave (GW) sources.We perform direct summation N -body simulations of the infall of GCs with different orbital eccentricities in the live background of a galaxy with either a shallow or steep density profile.We find that the GC acts as an efficient carrier for the IMBH, facilitating the formation of a bound pair.The hardening and evolution of the binary depends sensitively on the galaxy's density profile.If the host galaxy has a shallow profile the hardening is too slow to allow for coalescence within a Hubble time, unless the initial cluster orbit is highly eccentric.If the galaxy hosts a nuclear star cluster, the hardening leads to coalescence by emission of GWs within 3 -4 Gyr.In this case, we find a IMBH-SMBH merger rate of Γ IMBH-SMBH = 2.8×10 -3 yr -1 Gpc -3 .If the GC hosts a population of stellar BHs, these are deposited close enough to the SMBH to form extreme-mass-ratio-inspirals with a merger rate of Γ EMRI = 0.25 yr -1 Gpc -3 .Finally, the SMBH tidal field can boost the coalescence of stellar black hole binaries delivered from the infalling GCs.The merger rate for this merging channel is Γ BHB = 0.4 -4 yr -1 Gpc -3 .

Gravitational wave sources from inspiralling globular clusters in the Galactic Centre and similar environments