KEK-PH Lectures and Workshops 2021

Session

The KEK-PH + KEK-Cosmo joint workshop on "Primordial Black Holes"

19 Oct 2021, 13:00

Conveners

The KEK-PH + KEK-Cosmo joint workshop on "Primordial Black Holes": Short talks

• Kazunori Kohri (KEK)

The KEK-PH + KEK-Cosmo joint workshop on "Primordial Black Holes": 1st Invited Talk

• Mukaida Kyohei (KEK)

The KEK-PH + KEK-Cosmo joint workshop on "Primordial Black Holes": 2nd Invited Talk

• Kazunori KOHRI (KEK/Theory)

9. Primordial Black Holes from Long-Range Scalar Forces and Scalar Radiative Cooling

Mr Marcos Flores (UCLA)

19/10/2021, 13:30

Primordial black holes (PBHs) are a natural consequence of long-range scalar forces in the early Universe. These forces can lead to the formation of halos of heavy particles, Q-balls or oscillons even during the radiation dominated era. This same force removes energy and angular momentum from virialized systems via scalar radiation, leading to the subsequent formation of black holes. We will...

18. Primordial black holes in peak theory with a non-Gaussian tail

Dr Yuichiro Tada (Nagoya U)

19/10/2021, 14:00

In this work, we update the peak theory for the estimation of the primordial black hole (PBH) abundance,
particularly by implementing the critical behavior in the estimation of the PBH mass and employing the averaged compaction function for the PBH formation criterion to relax the profile dependence.
We apply our peak theory to a specific non-Gaussian feature called the exponential tail,...

19. Spins of primordial black holes formed in the radiation-dominated phase of the universe: first-order effect

Prof. Tomohiro Harada (Rikkyo U)

19/10/2021, 14:30

The standard deviation of the initial values of the nondimensional Kerr parameter a∗ of primordial black holes (PBHs) formed in the radiation-dominated phase of the universe is estimated to the first order of perturbation for the narrow power spectrum. Evaluating the angular momentum at turn around based on linearly extrapolated transfer functions and peak theory, we obtain the expression....

20. Ultrahigh-energy Gamma Rays and Gravitational Waves from Primordial Exotic Stellar Bubbles

Mr Qianhang Ding (HKUST)

19/10/2021, 15:00

We put forward a novel class of exotic celestial objects that can be produced through phase transitions occurred in the primordial Universe. These objects appear as bubbles of stellar sizes and can be dominated by primordial black holes (PBHs). We report that, due to the processes of Hawking radiation and binary evolution of PBHs inside these stellar bubbles, both electromagnetic and...

6. Primordial Black Holes and Gravitational Wave Observations

Dr Gabriele Franciolini (Geneva U)

19/10/2021, 16:00

Primordial Black Holes might comprise a significant fraction of dark matter in the Universe and can give rise to observable signatures at current and future gravitational wave experiments. First, we review the PBH model and discuss how accretion and clustering may affect the properties of PBH binaries. Second, we confront the PBH model with LIGO/Virgo data showing its upsides and shortcomings,...

8. Primordial black holes as a LIGO-Virgo and dark matter candidate

Dr Christian Byrnes (Sussex U)

20/10/2021, 16:00

Although black holes can be the remnants of dead stars, it is also possible that some are primordial. Such primordial black holes are the unique dark matter candidate which is not a new type of particle, and they could also explain some of the unexpected properties of the black hole mergers that LIGO and Virgo have detected. I will summarise the evidence and (fine-tuning) challenges behind...