專題演講 2025
週四中午定期舉辦專題演講
地點：教學研究大樓 S801-2講堂
時間：12:20-13:20
- 物理學系與地球科學系專題演講時間地點請見系網公告
- 內部演講與專題研講隔週輪流辦理，由中心成員主講
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is designed to probe dark energy by mapping the large-scale structure of the Universe using the 21 cm line of neutral hydrogen. With its wide field of view and daily coverage of most of the northern sky, CHIME offers unprecedented survey power in the redshift range 0.8 < z < 2.5 and has already achieved 21 cm detections through cross-correlation studies. Beyond cosmology, CHIME has also become a leading instrument for the study of fast radio bursts, pulsars, and 21 cm absorption systems. In this talk, I will discuss CHIME’s design, data, recent discovery and
scientific progress, especially the first detection of the 21 cm auto power spectrum.
Trans-Neptunian objects (TNOs) with large perihelion distances (q > 60 au) and semi-major axes (a > 200 au) provide insights into the early evolution of the Solar System and the existence of a hypothetical distant planet. These objects are challenging to observe, and thus their detections are still rare, yet they play a crucial role in constraining models of Solar System formation. Here we report the discovery of a Sedna-like TNO, 2023 KQ14, nicknamed ‘Ammonite’, with q = 66 au, a = 252 au and inclination i = 11°. The orbit of Ammonite does not align with those of the other Sedna-like objects and fills the previously unexplained ‘q-gap’ in the observed distribution of distant Solar System objects. Simulations demonstrate that Ammonite is dynamically stable over 4.5 Gyr. Our analysis suggests that Ammonite and the other Sedna-like objects may have shared a primordial orbital clustering around 4.2 Ga. Furthermore, the stable orbit of Ammonite favours larger orbits (~500 au) rather than closer ones for a large hypothetical planet in present-day trans-Neptunian space.
Venue: NTNU Gongguan campus B413
The release of the first black hole image by the Event Horizon Telescope (EHT) marked a new era in studying gravity and astrophysics in the strong-field regime. In this talk, I will introduce the key astrophysical concepts behind black hole imaging, explore how horizon-scale observations of M87 deepen our understanding of black hole astrophysics, and share some of my personal contributions to this rapidly evolving field.
[PHY colloquium] Venue: S101; Time: 14:20