October 30, 2023 to November 3, 2023
TD Lee Library
Asia/Shanghai timezone

Characterize the assembly of dark matter halos with protohalo size histories

Oct 31, 2023, 9:40 AM
20m
Conference Hall (TD Lee Library)

Conference Hall

TD Lee Library

901 Jianchuan Road, Minhang District, Shanghai, 200240
Talk Structure Formation halo: assembly & clustering

Speaker

Kai Wang (Kavli Institute for Astronomy and Astrophysics at Peking University)

Description

We propose a novel method to quantify the assembly histories of dark matter halos with the redshift evolution of the mass-weighted spatial variance of their progenitor halos, i.e. the protohalo size history. We find that the protohalo size history for each individual halo at z~0 can be described by a double power-law function. The amplitude of the fitting function strongly correlates to the central-to-total stellar mass ratios of descendant halos. The variation of the amplitude of the protohalo size history can induce a strong halo assembly bias effect for massive halos. This effect is detectable in observation using the central-to-total stellar mass ratio as a proxy of the protohalo size. The correlation to the descendant central-to-total stellar mass ratio and the halo assembly bias effect seen in the protohalo size are much stronger than that seen in the commonly adopted half-mass formation time derived from the mass accretion history. This indicates that the information loss caused by the compression of halo merger trees to mass accretion histories can be captured by the protohalo size history. Protohalo size thus provides a useful quantity to connect protoclusters across cosmic time and to link protoclusters with their descendant clusters in observations.

Primary author

Kai Wang (Kavli Institute for Astronomy and Astrophysics at Peking University)

Presentation materials