Seminar by Dr. Qianhang DING (Institute for Basic Science)

Ultralight bosons (ULBs) can form macroscopic superradiant clouds around spinning black holes. For scalar ULB mass μ ∼ 10−21 eV, its cloud-induced dynamical friction significantly impacts supermassive black hole (SMBH) binary dynamics. Considering orbital-decay power of the century-monitored OJ287 system, we place novel bounds restricting ULB mass range μ ≃ (8.5−22) ×10−22 eV independent of any dark matter assumptions and show ULB drag can also efficiently reconcile any future confirmations of the debated orbital decay excess. Meanwhile, we show that for scalar ULB masses μ ∼ 10−22 − 10−21 eV, boson cloud dynamical friction drives SMBH final-parsec evolution in ≲ 1 Gyr and suppresses the nanohertz gravitational wave background with turnover. Forthcoming pulsar timing array data and precise SMBH orbital timings will decisively test this scenario.

You may also like the following events from Department of Physics, CUHK 香港中文大學物理系:

• This Friday, 21st November, 02:00 pm, Colloquium by Professor Victor SOURJIK (Max Planck Institute) in Hong Kong

Also check out other Workshops in Hong Kong.