Taeho Ryu

On the likelihood of detecting gravitational waves from Population III compact object binaries

We study the contribution of binary black hole (BH-BH) mergers from the first, metal-free stars in the Universe (Pop III) to gravitational wave detection rates. Our study combines initial conditions for the formation of Pop III stars based on N-body simulations of binary formation (including rates, binary fraction, initial mass function, orbital separation and eccentricity distributions) with an updated model of stellar evolution specific for Pop III stars. We find that the merger rate of these Pop III BH-BH systems is relatively small ( 1 per cent) contribution of these stars to low-redshift BH-BH mergers. However, it remains to be tested whether (and at what level) rapidly spinning Pop III stars (homogeneous evolution) can contribute to BH-BH mergers in the local Universe.

Formation, disruption and energy output of Population III X-ray binaries

The first astrophysical objects shaped the cosmic environment by reionizing and heating the intergalactic medium (IGM). In particular, X-rays are very efficient at heating the IGM before it became completely ionized, an effect that can be measured through the 21 cm line of neutral hydrogen. High-mass X-ray binaries (HMXBs), known to be prolific X-ray sources in star-forming galaxies at lower redshifts, are prime candidates for driving the thermal evolution of the IGM at redshifts

Intermediate-mass black holes from Population III remnants in the first galactic nuclei

z > 20

Formation of runaway stars in a star-cluster potential

. Despite their importance, the formation efficiency of HMXBs from the first stellar populations is not well understood---as such, their collective X-ray emission and the subsequent imprint on the 21 cm signature are usually evaluated using free parameters. Using

An analytic method for identifying dynamically formed runaway stars

N

When do star clusters become multiple star systems? II. Towards a half-life formalism with four bodies

-body simulations, we estimate the rate of HMXB formation via mutual gravitational interactions of nascent, small groups of the first stars (Pop III stars). We run two sets of calculations: one in which stars form in small groups of five in nearly Keplerian initial orbits, and another in which two such groups collide (expected from mergers of host protogalaxies). We find that HMXBs form at a rate of one per

Turbulence-driven thermal and kinetic energy fluxes in the atmospheres of hot Jupiters

~10^{4}~{\rm M}_{\odot}

Population III X-Ray Binaries

in newly born stars, and that they emit with a power of

Numerical study of N = 4 binary–binary scatterings in a background potential

\sim 10^{41} ~{\rm erg}~{\rm s} ^{-1}

Interactions between multiple supermassive black holes in galactic nuclei: a solution to the final parsec problem

in the