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2024.11.20

[PDS seminar] The instability mechanism of compact multiplanet systems [EN]

<p>Numerical integrations of Kepler-like tightly packed planetary systems show that they are chaotic, with fairly short Lyapunov times, but that they can be stable against planet-planet or planet-star collisions for billions of years. Recent work by Petit et al. showed that this behavior was due to the overlap of three-body mean motion resonances. Caleb Lammers, Sam Hadden and I recently showed th...</p>

2024.11.08

A study on Kinematical Small-scale Fluctuations Vary with Galaxy Surface Density

<p>Massive galaxies usually observed as symmetric stellar motions and can be fitted well by the commonly used symmetric dynamical models. However, the stellar kinematics of many low-mass galaxies typically contain lots of small patches, causing the stellar second moment of velocity distribution to be non-smooth in small-scales and far from symmetry, we call these patches kinematical small-scale fl...</p>

2024.11.06

A chemical survey of exoplanet atmospheres with Ariel

<p>TBD</p>

2024.11.06

Breeding seeds to grow supermassive black holes in the cosmological context: theory and semi-analytical forecasts

<p>Supermassive black holes (SMBHs) are indispensable components of galaxy ecosystems. Their origin, growth, and feedback to the host galaxies are among the most fundamental questions in galaxy formation. In this talk, I will introduce a theoretical framework that coherently describes the formation of SMBHs from their seeding epoch to the present within the cosmological context. I will show that t...</p>

2024.11.01

Finding QPE-like systems in MOCCA simulation

<p>QPE(Quasi Periodic Eruptions) is new type of &nbsp;X-ray transient event first observed in 2018. It&#39;s characterized by the periodic X-ray outbursts in contrast to its quiescent radiation. One of the proposed model for QPE events involves a secondary body orbiting around the central massive black hole, generating periodic flares as the mass of the secondary object accretes onto the BH. These systems ...</p>

2024.10.30

Constraints on the tensor-to-scalar ratio r via a likelihood-based, optimal lensing reconstruction

<p>The cosmic microwave background (CMB) holds valuable information about the early Universe, including an imprint of its mass distribution that overshadows the faint signal from primordial gravitational waves, likely generated during inflation. Removing this imprint is crucial for future CMB observations to tightly constrain the tensor-to-scalar ratio r. This talk focuses on achieving the tightes...</p>

2024.10.23

The influence of GC evolution on the specific frequency in dwarf galaxies

<p>The presence of large fractions of metal-poor stars in dwarf galaxies still belonging to GCs raises questions about cluster mass loss and their formation mechanisms. These high ratios of metal-poor GCs relative to the number of low-metallicity field stars could imply that clusters in dwarfs have not lost enough mass, compared to more massive galaxies, or that the formation of field stars was su...</p>

2024.10.25

Galaxy Cluster Studies in the Era of High-resolution X-ray Spectroscopy

<p>Galaxy clusters, as massive, virialized halos within the cosmic web, serve as ideal laboratories for advancing our understanding of cosmology, plasma physics, and the nature of dark matter. High-resolution spectroscopy in soft X-rays will open a new window to map multiphase gas in galaxy clusters and probe physics of the intracluster medium, including but not limited to chemical enrichment hist...</p>

2024.10.18

Gravitational Lensing in the Kerr Spacetime: An Analytic Approach for Light and High-Frequency Gravitational Waves

<p>Current efforts of the Event Horizon Telescope aim at resolving the black hole shadow, mainly with the goal to probe the nature of the black hole and thus the underlying theory of gravity. Here, including other lensing features, in particular multiple images either of individual sources or in form of the so-called photon rings, will allow to place much tighter constrains on the spacetime parame...</p>

2024.10.22

Mapping the 3D Universe: From the Past to the Future, Bridging Theories and Observations

<p>This collaborative talk introduces the recent work in COSMO-3D group at EPFL’s Laboratory of Astrophysics (LASTRO). Jiaxi Yu (PhD student) will begin with a historical review of cosmology. The Universe started from a Big Bang, followed by inflation. The emission of the first light of the Universe, cosmic microwave background (CMB), happened in an opaque and dark era of the Universe afterwards....</p>