Conveners
Cosmology III
- Jae Hyeok Chang (JHU/UMD)
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Arushi Bodas10/05/2022, 14:00
Sudden onset of classical oscillations of a heavy field during inflation leaves a characteristic scale-invariance-breaking oscillatory feature in the power spectrum of primordial fluctuations. The presence of such features provides a unique opportunity to detect the dynamics of heavy fields during inflation. While such features are constrained to be small in adiabatic perturbations, we show...
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Clayton Ristow (University of Maryland)10/05/2022, 14:15
The Cosmic Microwave Background (CMB) spectrum matches that of a perfect blackbody with very high precision. Therefore, any model that distorts this spectrum is highly constrained. Motivated by certain dark sector models, we consider distortions caused by an axion-dark photon-photon coupling. In an axion dark matter background, this coupling converts CMB photons into invisible dark photons. We...
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Christina Gao10/05/2022, 14:30
We study how a Yukawa coupling of the Standard Model fermion to a light scalar affects the stellar structure of cold stellar remnants such as neutron stars. For a broad scalar mass range, the equation-of-state and stellar structure depends only the effective coupling $g_{\rm eff}=g_f m_f / m_\phi$, where $g_f$ is the Yukawa coupling, $m_f$ the fermion mass and $m_\phi$ the scalar mass. If the...
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Mr Lennart Röver (Institut für Theoretische Physik, Universität Heidelberg )10/05/2022, 14:45
The SKA allows to map the distribution of neutral hydrogen in the
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Universe over a vast redshift range. The three-dimensional 21cm power
spectrum found through this map can be used to perform precision tests
not only for several astrophysical phenomena but also for early Universe
cosmology. Even considering only a small redshift range it allows to
significantly improve current... -
Andreas Tsantilas (New York University)10/05/2022, 15:00
In this work, we present updated results on an ongoing dark matter search using astrometric weak gravitational lensing. Following the analysis in Mondino et al. (2020), results are reported on a dark matter search using proper motions on stars in the Magellanic Clouds from Gaia's most recent data release. Additionally, we assess our method on star-star lensing, and introduce a parallax...
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Dawid Brzeminski (University of Maryland - College Park)10/05/2022, 15:15
In the future, Stochastic Gravitational Wave Background can be measured by LISA. If the signal turns out to be produced by a causality-limited process such as a first-order phase transition, then the shape of its low-frequency spectrum would be independent of the details of the production mechanism. The slope of this low-frequency tail would encode information about the equation of state and...
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Fei Huang (ITP CAS and UC Irvine)10/05/2022, 15:30
One signature of an expanding universe is the time-variation of the cosmological abundances of its different components. For example, a radiation-dominated universe inevitably gives way to a matter-dominated universe, and critical moments such as matter-radiation equality are fleeting. In this talk, we point out that this lore is not always correct, and that it is possible to obtain a form of...
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Ido Ben-Dayan10/05/2022, 15:45
A limiting temperature of a species can cause the Universe to asymptote to it yielding a de-Sitter (dS) phase due to macroscopic emergent behavior. The limiting temperature is generic for theories slightly shifted from their conformal point. We demonstrate such behavior in the example of unparticles/Banks-Zaks theory. The unparticles behave like radiation at high energies reducing the Hubble...
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