Publications by authors named "Donghui Jeong"
Article Synopsis
- The study investigates compact binary coalescences with at least one component mass between 0.2 and 1.0 solar masses using data from Advanced LIGO and Advanced Virgo detectors over six months in 2019, but they found no significant gravitational wave candidates.
- The analysis leads to an upper limit on the merger rate of subsolar binaries ranging from 220 to 24,200 Gpc⁻³ yr⁻¹, based on the detected signals’ false alarm rate.
- The researchers use these limits to set new constraints on two models for subsolar-mass compact objects: primordial black holes (suggesting they make up less than 6% of dark matter) and
Certain anomalies in the CMB bring out a tension between the six-parameter flat ΛCDM model and the CMB data. We revisit the PLANCK analysis with loop quantum cosmology (LQC) predictions and show that LQC alleviates both the large-scale power anomaly and the tension in the lensing amplitude. These differences arise because, in LQC, the primordial power spectrum is scale dependent for small k, with a specific power suppression.
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- - The difference in the Hubble parameter values derived from local measurements versus those from the cosmic microwave background (CMB) has led to a deeper investigation of the assumptions behind both methods.
- - The position of the recombination peak in the CMB B-mode power spectrum acts as a new standard ruler, allowing for cross-checks against the acoustic peaks in the CMB temperature power spectrum and helping to address the Hubble tension.
- - Future stage-IV B-mode experiments could achieve a measurement precision better than 2%, which would also help determine the speed of gravitational wave propagation in the early Universe.
We explore the possible spectrum of binary mergers of subsolar mass black holes formed out of dark matter particles interacting via a dark electromagnetism. We estimate the properties of these dark black holes by assuming that their formation process is parallel to Population-III star formation, except that dark molecular cooling can yield a smaller opacity limit. We estimate the binary coalescence rates for the Advanced LIGO and Einstein telescope, and find that scenarios compatible with all current constraints could produce dark black holes at rates high enough for detection by Advanced LIGO.
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- The study focuses on how small-scale adiabatic perturbations dissipate when the Universe is hotter than approximately 0.5 keV, examining the effects of acoustic damping on various cosmic processes.
- When wavelength falls below a critical damping scale, acoustic modes diffuse and thermalize, resulting in increased entropy and impacting phenomena like relic neutrino numbers and primordial nucleosynthesis.
- The research establishes a new limit on the amplitude of primordial fluctuations, showing Δ(R)(2) < 0.007 for certain scales and a model-dependent limit of Δ(R)(2) < 0.3 for much larger scales.
Many inflationary theories introduce new scalar, vector, or tensor degrees of freedom that may then affect the generation of primordial density perturbations. Here we show how to search a galaxy (or 21-cm) survey for the imprint of primordial scalar, vector, and tensor fields. These new fields induce local departures to an otherwise statistically isotropic two-point correlation function, or equivalently, nontrivial four-point correlation functions (or trispectra, in Fourier space), that can be decomposed into scalar, vector, and tensor components.
View Article and Find Full Text PDFWe probe the pure Einstein gravity contributions to the second-order density power spectrum. On the small scale, we discover that Einstein's gravity contribution is negligibly small. This guarantees that Newton's gravity is currently sufficient to handle the baryon acoustic oscillation scale.
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