原子核量子光学、量子点材料、超快太赫兹、微腔激子极化激元 | 本周物理讲座

摘要：

The James Webb Space Telescope (JWST) is transforming our understanding on galaxy formation and evolution, revealing distant galaxies deep into the epoch of reionization and red sources that were simply unknown pre-JWST. In this talk, I will discuss two key areas, with a focus on the challenges in modeling the spectral energy distributions in the JWST era. First, a central science goal of JWST is finding the first galaxies, which often requires modeling of photometric data to select candidates for spectroscopic follow-up. I will show the modeling work that turns the nearby cluster A2744 to one of deepest views of our universe, as part of the UNCOVER survey. The resulting rich, public dataset, reveals stellar populations across 0.2 < z < 13, and helps to lead to the discovery of the surprisingly large galaxies at z > 12. I will also briefly discuss how this exquisite dataset is poised to redefine our census of galaxy populations. Second, the optical/IR sensitivity of JWST has led to the discovery of compact red sources, initially interpreted as apparently massive galaxies at z > 7. This interpretation yields a strongly accelerated time line compared to standard models of galaxy growth. Yet, major uncertainties remain about their nature due to the limited photometric data. I will present detailed studies of these so-far mysterious "little red dots", enabled by the spectroscopic data from the RUBIES program. Remarkably, we find clear signatures of evolved stellar populations, the formation histories of which extend hundreds of millions of years into the past in galaxies only 600 -- 800 Myr after the big bang. Confoundingly, some of them exhibit broad Balmer emission lines, suggesting that dust-reddened AGNs contribute to, or even dominate, the spectral energy distributions red-ward of ~ rest 0.6μm. I will explore potential origins and evolutionary tracks, from the cores of massive galaxies to low-mass galaxies with over-massive black holes, and conclude with remaining puzzles and possible future directions to form a complete physical picture of these intriguing systems.

摘要：

In a paradigm-shifting article “More is different” in 1972, Phil Anderson pointed out that new properties can emerge from a many-body system, which cannot be derived from the constituent particles. In this talk I would argue that even two or three can be regarded as “more” in the world of superconductors. During this talk, I will highlight the unnoticed beauty of multiband of i ron-based superconductors, including 1.  Emerge n ce of topological band which coexists with superconductivity, leading to the discovery of Majorana zero mode; 2. Interplay of multicomponent superconductivity, leading to the discoveries of exotic paring with time-reversal symmetry breaking and fractional vortex; 3. Contribution of Hund coupling towards pairing in this unique class of superconductors.

摘要：

Orbits and physical properties of exoplanets may keep evolving after formation. For example, it has long been discussed that the shortest-period planets may have orbits unstable to tidal dissipation and spiral into their host stars. Recent transit observations of low-mass planets have also provided evidence for evaporation of their atmospheres, which provides clues to the internal composition of those planets. Understanding such evolution is crucial for comprehending the diversity of exoplanetary systems and placing our solar system in a broader context. In this talk, I will present our ongoing efforts to probe these changes statistically by examining the dependence of exoplanet occurrence rates on stellar age. I will discuss our recent work on deriving age-dependent occurrence rates of giant planets orbiting Sun-like stars using isochronal ages, and also mention insights into rotation-based ages from high-resolution spectroscopy of Sun-like stars in twin binaries.

报告人简介：

Dr. Yifan Wang is a postdoc at Max Planck Institute for Gravitational Physics (Albert Einstein Institute). He obtained his Ph.D. degree at the Chinese University of Hong Kong and B.S. degree at University of Science and Technology of China. His current research interests are finding more compact binary coalescence systems through gravitational wave, utilizing more advanced search strategies or new waveform models incorporating novel physic effects.