About me

My name is Yun-Ao Xiao (肖云奥), a 1st-year PhD student in WSGP group, NAOC. I’m working under the guidance of Prof. Hu Zou, focusing on stellar streams, dwarf galaxies, and the Milky Way dark matter halo.

My Research

In the formation and evolution of galaxies, halos are built through mergers with satellite galaxies. When dwarf galaxies undergo tidal stripping, their stars and globular clusters are stretched out to form tidal streams. Mergers with lower mass ratios may also produce or enhance the thick disk component of galaxies. Since the dynamical timescales required for the global equilibrium of the outer halo are quite long, stars, clusters, tidal streams, and satellite galaxies in the halo serve as excellent tracers for probing the mass distribution and dynamical properties of the dark matter halo.

Based on photometric data with a time baseline of 10–20 years from SDSS and DESI, we constructed a proper motion catalog covering 12,589 square degrees, containing over 100 million PSF sources, using a galaxy-based reference frame. More than 40% of the sources in this catalog are fainter than 21.5 mag (in the r-band). The systematic and random errors of proper motions, evaluated using 730,000 quasars, show that most sources have systematic errors under 0.5 mas/year, with precision reaching 3~6 mas/year. Utilizing this deeper proper motion catalog, we aim to systematically search for tidal streams and satellite galaxies in combination with DESI and other photometric and spectroscopic data, facilitating dynamical and chemical studies of the Milky Way halo and its substructures.

In addition to the substructures within the Milky Way halo, we are also interested in stellar streams and dwarf galaxies in nearby galaxies. Thanks to deeper photometric and spectroscopic surveys, we can resolve member stars within certain distant substructures and study them using similar methods as those applied to the Milky Way. For substructures where individual stars cannot be resolved, we are also trying to detect them using CNN and other techniques in processed images.

Skills in Programming, Observing, and Data Processing

I’m proficient in multiple programming languages, and I frequently use servers such as NERSC to handle large datasets and run complex analyses efficiently.

My observational experience is extensive, having used multiple telescopes across China and the 200-inch Hale Telescope (P200), and also handled some data from the UArizona Bok 2.3-meter Telescope (Bok). I’m also contributing to the photometric pipeline development for Chinese Space Station Telescope (CSST), Multi-channel Photometric Survey Telescope (Mephisto), and the 60-90cm Schmidt telescope.

In addition, during my undergraduate studies, I participated in the development and testing of the imaging detectors for the Cherenkov telescopes of Large High Altitude Air Shower Observatory (LHAASO), gained some experience in high-energy observations and cosmic-ray physics.

These experiences have equipped me with advanced skills in data reduction, processing, and pipeline design, enabling me to efficiently manage large photometric datasets and perform high-quality data analyses for various astronomical research needs.

Involvement in the DESI Collaboration

I have participated in Dark Energy Spectroscopic Instrument (DESI) observations, gaining hands-on experience with spectral data acquisition and processing. This has helped me develop expertise in spectral observation techniques and data analysis skills essential for large-scale astronomical surveys.

I am actively involved in the DESI Milky Way Survey Working Group (MWS) and frequently participate in discussions, where I have gained substantial knowledge on the study of Milky Way stellar streams and learned how to use these streams as probes to investigate the structure and properties of the Milky Way’s dark matter halo.

Working in the DESI Collaboration has provided me with valuable insights into the inner workings of large astronomical collaborations and advanced my skills in handling, reducing, and interpreting spectral data for the study of galactic structure and kinematics.

For more info

My office is located at A449, NAOC. Feel free to visit if you would like to discuss any of these topics!