CPLUOS Astrophysics team meeting

Monday 15 Nov 2021, 16:30 → 17:55 Asia/Seoul

물리학과

https://uos-ac-kr.zoom.us/j/8264902652

COSMOLOGY

1 Dr.Sangnam Park's Report - FDM_Offset

Speaker: Sangnam Park

2 Hyeonmo's report - CDM Halo Collision for Gadget2 Simulation

Speaker: Hyeonmo Koo (University of Seoul)

• CDM Halo Collision for Gadget2 Simulation
  • Some Bumps in CDM Simulation
    • In Initial Velocity [28.184km/s] - Velocity Decrease [28.184km/s] graph,
      • 1st bump : v_0 = 20.758473157164275
      • 2nd bump : v_0 = 27.314859836299792
      • 3rd bump : v_o = 42.87933659802936
      • A strange thing is seen in the velocity decrease curve of CDM, that as the initial velocity v_0 increases, Δv is not slight, but decreases with a few bumps.
    • The result of comparing this result with the graph in FDM is as follows.
      • As for the initial velocity, FDM data is higher than CDM data from 0 to 42.8933659802936, and FDM data is almost identical to CDM data from 42.8933659802936.
  • In t[Gadget Unit] - r[kpc] graph,
    • v3 = 42.85
    • v2 = 27.27
    • v1 = 20.75
  • In x[kpc] - y[kpc] graph, (M = 21, V = 18.0)
    • Halo's oscillation because of relexation
  • T_(1/2) = 0.06, τ_gadget = 0.028τ_c

3 Young's report. FoF and MST algorithm

Speaker: Young Ju

• FoF and MST algorithm
  • Test FoF for 50,000 noise data
  • The FoF algorithm of astropy halotools takes only positive coordinates.
  • So, we translate parallel coordinate and compute FoF.
  • Linking length = 0.3 * mean separation (5.23) ~ 1.6
    • Returned cluster with more than 50 member = 7
  • Check density of random clusters : To find proper minimum member
  • In Cluster id - ρ graph,
  • Black line indicate noise 50,000 density : ρ_Noise = Noise / Volume = 0.00625
  • Most of density for clusters is higher than noise level
  • In Distance - Number graph,
    • Distance between two cluster pairs _(50)C_2
    • Distance between galaxy and center of clusters
    • Linking length = 10 is proper because the LL is not too smaller than average of size of cluster.

4 CHOA(Cosmology of High-Order Statistics)

Speaker: Se Yeon Hwang

5 Dr.Sabiu's Report

Speaker: Dr Cristiano Sabiu (University of Seoul)

• Title : Probing Ultra-light Axion Dark Matter from 21cm Tomography using Convolutional Neural Networks.

6 Discussion