Primordial Black Holes and Gravitational Waves Kin-Wang Ng ( ) - - PowerPoint PPT Presentation

Primordial Black Holes and Gravitational Waves

Kin-Wang Ng (吳建宏) Institute of Physics & Institute of Astronomy and Astrophysics Academia Sinica, Taiwan Workshop on Gravitational Wave activities in Taiwan (GWTW) Jan 15, 2017

Suyama

Suyama

Zel'dovich & Novikov (1967), Hawking (1971)

LIGO events are indirect signal of DM ! Versus astrophysical BHs from collapses of high-mass stars

Production of PBHs in inflation

N is e-foldings before the end

• f inflation

e.g. Trapped inflation with a steep potential

Cheng, Lee, Ng 16

• - - - m2φ2/2

all rescaled by Mp inflaton-photon interaction φ EŸB à photon production

Production of 10-100M¤ PBHs

Density perturbation Δζ

2 = (δρ/ρ)2

PBH bound - deduced from astrophysical and cosmological constraints on PBH mass fraction β(M)

backreaction due to photon production

Associated Stochastic Gravitational waves

Spectral energy density

Pulsar timing array experiments

Sources due to transverse traceless part

• f higher-order density perturbation

Tµν

GWs associated with PBHs of different masses in inflation models

Garcia et al. 16 Cheng et al. 16 Inomata et al. 16

Conclusion

• The binary BHs observed by aLIGO gravity-wave

detectors may be primordial BHs

• 10-100 M¤ PBHs could be dark matter
• Production of these PBHs in inflation models
• Also can produce a wide range of PBH masses
• How to distinguish PBHs from astrophysical BHs?

PBHs have less spins – need more data and statistics

• Associated stochastic gravitational waves

polarized (+ mode / - mode) GWs in trapped inflation

• Simulations on the evolution of PBHs G.-C. Luo, H. Tu

binaries formation, merging rate, stochastic GW background