Qinxun Li

Qinxun Li

Graduate student at Department of Physics and Astronomy in University of Utah

Talks and presentations

Cluster Seminar: Subhalo Properties in SDSS DR7 with Galaxy-galaxy Lensing

October 04, 2022

talk, University of Michigan, Department of Astronomy, Ann Arbor, US

This is a talk of cluster seminar of Department of Astronomy, Umich. In this talk, I will focus on our recent work about subhalo properties in Yang et al. (2007) 's group catalog based on SDSS DR7. We devide satellite galaxies into different stellar mass and BCG-center separation bins, then measure the lensing signals around these satellites. We discover an unreported selection effect between separation and host halo mass and use a weighting method to correct it. With a 2 free paramater model to describe excess surface density of subhalo, we fit the weighted lensing signal by MCMC. In this talk, I will first introduce galaxy-galaxy lensing method and subhalo density profile, then talk about the methods and main results of this work.

2022 PKU-DoA Undergraduate Astronomy Symposium: Subhalo Properties from SDSS Weak Lensing

September 23, 2022

Talk, Peking University, The Kavli Institute for Astronomy and Astrophysics and Department of Astronomy, Beijing, China

This is a talk of 2022 PKU-DoA Undergraduate Astronomy Symposium. In this talk, I introduce my work on subhalo mass measurement from SDSS weak lensing. We use Luo et al. (2017) SDSS DR7 shape catalog to study subhaloes in Yang et al. (2006) group catalog. We find an unreported selection bias between host halo mass and separation between satellite galaxies and their central galaxies. We develop a weigting method to correct this bias. With a 2 free paramater model to describe excess surface density of subhalo, we fit the weighted lensing signal by MCMC. In this talk, I will first introduce galaxy-galaxy lensing method and subhalo density profile, then talk about the methods and main results of this work.

Undergraduate Academic Annual Conference: Dark Matter Halo Mass Measurement with Galaxy-galaxy Lensing

June 11, 2022

Talk, University of Science and Technology of China (USTC), Department of Astronomy, Hefei, China

This is a talk of Undergraduate Academic Annual Conference of Department of Astronomy, USTC. In this talk, I introduce basic principles of using galaxy-galaxy lensing to measure dark matter halo mass and some recent progress of two of my works, satellite lensing of SDSS and comparison between weak lensing mass and caustic mass.