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2023.10.30

Cluster Intrinsic Alignment in DES Y1

<p>Clusters of galaxies trace the most non-linear peaks in the cosmic density field. The weak gravitational lensing of background galaxies by clusters can allow us to infer their masses. However, galaxies associated with the local environment of the cluster can also be intrinsically aligned due to the local tidal gradient, contaminating any cosmology derived from the lensing signal. In this talk, ...</p>

2023.10.27

First-year JWST results of high-redshift moderate-luminosity AGN

<p>I present the latest results from a JWST Cycle 1 GO program, in which 12 of the lowest-luminosity z&gt;6 quasars selected from the deep Subaru/HSC survey are observed with NIRCam imaging and NIRSpec Fixed-Slit spectroscopy. We have successfully detected stellar light of quasar host galaxies in NIRCam F150W and F356W images, which straddle the redshifted 4000 angstrom break. A self-developed image ...</p>

2023.10.24

Optimization of Cosmological Information Extraction with Minkowski Functionals

<p>Galaxy survey provides an important window for the exploration of fundamental physics by accurately mapping the large-scale structure of the Universe (LSS), which is expected to lead to great scientific discoveries. In cosmology, LSS encodes abundant key cosmological information (e.g., baryon acoustic oscillations, neutrino masses, primordial non-Gaussianities, gravity properties, and cosmologi...</p>

2023.10.26

Exploring the early Milky Way with metal-poor stars

<p>Old low-metallicity (“metal-poor”) stars provide us a unique window to explore the early evolution and formation of our Milky Way as well as the early nucleosynthesis in the universe. In this talk, I would like to introduce the art of Galactic archaeology with metal-poor stars, mainly using the joint efforts between LAMOST and Subaru in the past few years as an example. A homogeneous high-pre...</p>

2023.10.24

An Overview of Stellar Evolution and Pollution in AGN Disk (SEPAD) and their Implication on the Stellar Dynamics in the Galactic Center and around other Supermassive Black Holes

<p>Extended regions of accretion disks around supermassive black holes in bright AGNs are prone to gravitational instability, star formation and stellar dynamical evolution with feedback to the disks&#39; structure. Spectroscopic data provide vital clues on the stellar and residual black hole populations. Their dynamical interaction with each other, their natal disks, and other massive companions in a...</p>

2023.10.20

TRANSforM: stellar parameters estimated from LAMOST DR10 M dwarfs

<p>The accurate determination of stellar parameters in M-type stars holds significant importance in various astronomical studies. In our study, we employed a transfer learning method coupled with PHOENIX synthetic spectra to estimate fundamental atmospheric parameters (Teff, log g, [M/H], [α/M]) and radial velocities (RV) for an extensive dataset encompassing 581,778 M dwarfs obtained from the Lo...</p>

2023.10.17

existing tensions in ΛCDM model

<p>The concordance or standard Λ Cold Dark Matter (ΛCDM) model is a well-defined, predictive and simple cosmological model. A number of challenges of the standard ΛCDM model have been emerging during the past few years, which has been summarized by recent reviews.In this talk, I will give a brief introduction to several existing signals in cosmological and astrophysical data that appear to be i...</p>

2023.10.13

Multiband gravitatioanl wave observations of stellar binary black holes

<p>The ground-based gravitational wave (GW) observatories discover a population of merging stellar binary black holes (BBHs), which are promising targets for multiband observations by the low-, middle-, and high-frequency GW detectors. We investigate the multiband GW detections of BBHs and demonstrate the advantages of such observations in improving the localization and parameter estimates of the ...</p>

2023.10.10

Obstacles from interstellar matter and distortion for warp drive travel

<p>We investigate obstacles of superluminal “warp drive” travels from interactions with interstellar matter and from curvature effects. The effect of collision of interstellar dust particles and photons with the spacecraft will all lead to a pressure proportional to the apparent velocity of the spaceship vs. The force exerted on the spacecraft from the curvature effect has two non-trivial compon...</p>

2023.09.26

Implication of UV variability for the abundance of bright galaxies at cosmic dawn 紫外光度波动对宇宙黎明时明亮星系丰度的影响

<p>The JWST has uncovered a large population of UV-bright galaxies at redshifts above ~10, which surpasses the predictions from a range of theoretical models developed based on lower redshift galaxies. While various solutions have been proposed focusing on systematically increasing the UV photon yield in high-redshift galaxies, I will discuss in this talk an alternate solution from UV variability....</p>