Lunch talk on Mar. 7, 2022

Photometric Objects around Cosmic Webs (PAC): Taking Full Use of the Spectroscopic and Photometric Surveys

Speaker: Kun Xu (SJTU)

Venue: Video Conference

Time: 12:30 PM, Monday, Mar. 7, 2022

Abstract: 

In recent years, upcoming large and deep spectroscopic and photometric cosmological surveys (e.g., DESI, LSST, Euclid, CSST, PFS) will uncover the universe to an unprecedented width and depth. Spectroscopic and photometric surveys both have their advantages and disadvantages. Spectroscopic surveys can precisely measure the 3D positions while photometric surveys are deeper and more complete. Thus, methods and techniques which can combine and take full use of both these two surveys will bring much more information for galaxy formation, galaxy-halo connection and cosmology studies. I’d like to introduce our new method PAC that can estimate the projected density distribution of photometric objects with certain physical properties (e.g., luminosity, mass, color etc.) around spectroscopic objects. As an example, we apply the PAC method to the CMASS spectroscopic and HSC-SSP PDR2 photometric samples. We can accurately measure the stellar-halo mass relation (SHMR), stellar mass function (SMF) and conditional stellar mass function (CSMF) for a wide stellar mass range ($10^{9.0}-10^{12.0} M_{\odot}$) at redshift $z~0.6$. We also find morphology, color and galaxy size dependences of the SHMR, which may indicate the existence of so called galaxy assembly bias. PAC can have many other applications in galaxy formation and cosmology with the large and deep surveys.

Report PPT:  SWIFAR_Kun Xu.pptx