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2024.04.02

Baryon Recycle in Disc Galaxy

<p>We utilize the public Gizmo code to simulate twelve galaxies from the NIHAO suite simulated with the ESF-Gasoline2 code, then compare the corresponding galaxies in the two simulations. We find that while both codes with the same initial conditions and large-scale environments can successfully produce similar disc galaxies, significant differences are still seen in many properties of the galaxie...</p>

2024.03.26

Primordial non-Gaussianity (PNG) and Its Detection by Cosmolgical Surveys

<p>The simplest single-field inflation models predict a nearly Gaussian distribution of primordial density perturbations. However, the non-Gaussianity of the primordial density field serves as a powerful probe into the physics of the early universe, especially when considering more complex inflation models. The Cosmic Microwave Background (CMB) bispectrum has provided the tightest constraint on th...</p>

2024.03.19

Can we test cosmic homogeneity and isotropy?

<p>The Cosmological Principle (CP) was a major achievement of modern cosmology to turn qualitative statements into quantitative ones. It makes the strong assumption that space is globally homogeneous and isotropic. By doing so, it reduces Einstein’s Field Equations to provide highly symmetric cosmological models. The latter then enable us to interpret a very sparse amount of data and put them int...</p>

2024.03.12

A decelerating bar in the Galaxy

<p>The bar of the Galaxy is believed to slow down. We use an axisymmetric background potential plus a central bar model to perform the test particle simulations in order to investigate the possible origin of the phase space spirals and the thin-disc-like low-metallicity stars (VMPs). The Gaia data reveal a two-armed phase spiral pattern in the local &nbsp;plane inside the solar radius. On the contrary,...</p>

2024.03.05

Towards a Unified Model of Dwarf Galaxy Star Formation and Halo Connection with UniverseMachine

<p>Dwarf galaxies provide rich constraints on galaxy formation, reionization, and the nature of dark matter. However, flexible models of their star formation histories in a cosmological context are lacking. We introduce a novel framework for connecting dwarf galaxy dark matter assemblies and star formation histories based on the empirical model UniverseMachine (UM). Our framework is flexible, such...</p>

2024.01.09

Exploring the new high-redshift frontier with the James Webb Space Telescope

<p>The advent of the James Webb Space Telescope (JWST) has brought the study of early galaxy formation to a new level. Shortly after it began its scientific operation, JWST revealed a large number of candidate galaxies at redshift (z) greater than 11 when the universe was less than ~420 million years old, some of which could even be at z ~ 20 (age of the universe ~180 million years). This was comp...</p>

2024.01.02

Expanding our perspective to the distant universe through Intensity Mapping of HI and CII

<p>As a prevalent and widely distributed component of galactic gas, neutral atomic hydrogen (HI) and Carbon lines (CO, CII) play a crucial role in comprehending various astrophysical processes, including star formation histories, galaxy interactions, and the tracing of cosmic large-scale structures. However, the sensitivity limitations of telescopes pose challenges to directly measuring line signa...</p>

2023.12.19

A New AGN Photoionization Model and Multi-wavelength Metallicity Diagnostics

<p>The photoionization model of narrow-line regions (NLRs) in active galactic nuclei (AGNs) has been investigated for decades. Many published models are restricted to simple linear scaling abundance relations, dust-free assumption, uniform AGN radiation field, and using one specific photoionization code, which restricts them from providing a satisfactory prediction on a broad range of AGN observa...</p>

2023.12.12

Cross-correlation between the Thermal Sunyaev–Zeldovich Effect and the Integrated Sachs–Wolfe Effect

<p>Understanding the composition and distribution of baryonic matter in the Universe is a crucial step toward unraveling the mysteries of its formation and evolution. Early estimates and numerical simulations show that most baryons are “missing,” whereas the baryons that are already made into stars and galaxies constitute a small portion of the total baryon budget. Therefore accurate constraints...</p>

2023.12.05

Reconstruction of Cosmological Initial Density Field with Observations from the Epoch of Reionization

<p>Initial density distribution provides a basis for understanding the complete evolution of cosmological density fluctuations. While reconstruction in our local Universe exploits the observations of galaxy surveys with large volumes, observations of high-redshift galaxies are performed with a small field of view and therefore can hardly be used for reconstruction. Here we propose to reconstruct t...</p>