首页

2023.06.12

The Power of Milky Way's Stellar Streams Enabled by Multi-Object Spectroscopic Surveys

<p>In this talk, I will discuss two ongoing spectroscopic programs to study the stellar streams in our Milky Way and highlight a few latest scientific results from these two programs. The Southern Stellar Stream Spectroscopic Survey (S5), started in 2018, is the first systematic program pursuing a complete census of known streams in the Southern Hemisphere. The science results from S5 include a ho...</p>

2023.05.10

A dynamical model and structure decomposition of barred galaxies

<p>Galaxy structures are fossil records of their assembly history. Modern IFU spectrographs offer the ability to map the spatial distribution of the motions, ages, and chemical abundances of stars in galaxies, which provide unprecedented detailed view of galaxies structures. But the information are still blended along the line-of-sight. Decomposition of galactic structures in a physical way is cha...</p>

2023.05.23

Binaries of the first stars as progenitors of compact object mergers

<p>A grand challenge for modern astrophysics is to understand star and galaxy formation in the first billion years of cosmic history. In particular, the first generation of stars born in extremely metal-poor/free primordial gas, the so-called population III (Pop III), are believed to have distinct features compared with present-day stars: They are more likely to become massive black holes due thei...</p>

2023.04.26

21cm Cosmology in the Post-Reionization Universe

<p>I will discuss some recent progress in 21cm line intensity mapping within the SKA cosmology science working group. In particular, we report the first direct detection of the cosmological power spectrum using 21cm line (2301.11943), derived from interferometric observations with the L-band receivers of the MeerKAT radio telescope. I review the challenges in analysing the MeerKAT data and present...</p>

2023.04.25

Unveiling BCGs and their host clusters using the ICL and Satellite Galaxy Populations

<p>At the heart of every galaxy cluster is the brightest central galaxy (BCG). The central location of the BCG along with its unique formation history yield the underlying galaxy-dark matter halo connection. This statistical correlation allows us to enhance our understanding of the assembly and evolution of BCGs over cosmic time. However, we gain further insight into the formation and evolution of...</p>

2023.04.19

Galaxy-Scale Strong Gravitational Lensing at High Angular Resolution

<p>Anomalous flux ratios between lensed images can provide a key test of the dark matter sub-halo population, and hence the nature of dark matter. However, the observed anomalous flux ratios at radio frequencies can also be the result of systematics associated with our lack of knowledge about the source structure, source variability, propagation effects and microlensing of compact objects within t...</p>

2023.04.11

X-ray reflection spectroscopy on black hole X-ray binaries

<p>Black hole X-ray binaries are bright accreting systems that can undergo apparent state changes on the reasonable timescales for human. These systems are good analogy to their supermassive counterparts: active galactic nuclei. X-ray reflection spectroscopy is a powerful tool to study the accretion geometry under different regimes. In this talk, I will present how we use X-ray reflection spectros...</p>

2023.06.30

Revealing the Recycled inflow of the massive galaxies at high redshift

<p>The gas surrounding galaxies is known as the circumgalactic medium (CGM) which is considered to be deeply coupled with the evolution of galaxies. Although lots of works have been done, how galaxies co-evolve with the CGM is still poorly understood. To explore the CGM-galaxy ecosystem, especially the baryon cycle, we conduct observations on the high redshift CGM. First, we study the gas surroun...</p>

2023.06.16

Flow Annealed Kalman Filters: Gradient-free inference for expensive forward models

<p>For many scientific applications the forward model consists of an expensive black-box simulator without easy access to gradients of the forward model. In such a situation, inference can be challenging, with standard gradient-free sampling algorithms requiring an intractably large number of serial model evaluations. In this talk I will introduce the flow annealed Kalman filter for approximate Ba...</p>

2023.06.09

3D Structure and Extinction of Nearby Molecular Clouds

<p>The 3D structure and extinction law are studied for the Taurus, Orion, Perseus and California molecular clouds (MCs) based on the LAMOST and APOGEE spectroscopy. Extinctions are calculated from color excess derived from the Blue Edge methods. In combination with the distance from the Gaia, &nbsp;a 3D extinction map and the structure of these MCs can be retrieved and the clouds that overlap in the sk...</p>