科学研究
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2024.01.09
Exploring the new high-redshift frontier with the James Webb Space Telescope
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...
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2024.01.02
Expanding our perspective to the distant universe through Intensity Mapping of HI and CII
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...
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2023.12.26
The “Missing baryons” in the cosmic web—what is it? Where is it? How much?
Previous studies of galaxy formation have shown that only 10 per cent of the cosmic baryons are in stars and galaxies, while 90 per cent of them are missing. In this talk, I will present several observational studies that coherently find significant evidences of the missing baryons. The first measurement is the cross-correlation between the thermal Sunyaev-Zeldovich effect with gravitational le...
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2023.12.19
A New AGN Photoionization Model and Multi-wavelength Metallicity Diagnostics
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...
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2023.12.12
Cross-correlation between the Thermal Sunyaev–Zeldovich Effect and the Integrated Sachs–Wolfe Effect
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...
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