CPLUOS Astrophysics team meeting

Monday 8 Nov 2021, 16:30 → 17:55 Asia/Seoul

물리학과

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

16:30 → 17:45 COSMOLOGY

16:30 Dr.Sangnam Park's Report - FDM_Offset

Speaker: Sangnam Park

16:45 Hyeonmo's report - CDM Halo Collision for Gadget2 Simulation

Speaker: Hyeonmo Koo (University of Seoul)

17:00 Young's report. FoF and MST algorithm

Speaker: Young Ju

• FoF and MST algorithm
  • Random + Noise data
    • Now the number of galaxies in cluster follows the exponential distribution
    • The minimum number = 52
    • The maximum number = 318
    • Total number of galaxies = 5008
  • Noise = 5k
    • (Min_number, MGS, MST, DBSCAN, Hierarchical)
      • (3, 587, 246, 44, 246)
      • (10, 126, 59, 44, 59)
      • (20, 61, 28, 39, 28)
      • (50, 47, 18, 39, 18)
  • Noise = 50k
    • (Min_number, MGS, MST, DBSCAN, Hierarchical)
      • (3, 534, 1, 1, 1)
      • (10, 513, 1, 1, 1)
      • (20, 473, 1, 1, 1)
      • (50, 334, 1, 1, 1)
  • FoF test : Check returned clusters by changing linking-length
    • Linking-length ~ 2
      • Noise = 5000
      • Noise = 10000
      • Noise = 50000
    • Linking-length ~ 5
      • Noise = 5000
      • Noise = 10000
      • Noise = 50000
    • Linking-length ~ 9.3
      • Noise = 5000
      • Noise = 10000
      • Noise = 50000
    • Linking-length - Noise size graph
      • Minimum >= 3
        • Center value = 433.0
      • Minimum >= 50
        • Center value = 19.0
  • FoF test : This time I use mean separation
    • (Minimum #, 5000, 10000, 50000)
    • (3, 58, 29, 30)
    • (50, 5, 3, 3)
    • Noise = 5000 → Mean separation = 9.3
    • Noise = 10000 → Mean separation = 8.1
    • Noise = 50000 → Mean separation = 5.3

17:15 CHOA(Cosmology of High-Order Statistics)

Speakers: Se Yeon Hwang, Sumi Kim (University of Seoul)

• CHOA(Cosmology of High-Order Statistics)
  • Calculating for the box case
  • Tetrahedron &  Box mean comparison(NGC) graph
    • In the graph, the box is broken about 160r(Mpc).
      • Because of the box shape
        • Have to multiply 1.414......
  • Checking and reviewing our results......
  • How to deal with the 4pcf covariance matrix?
    • In our result...... → 50 ~ 200(Mpc/h), step size = 5(Mpc/h)
    • (pcf, No wiggle, BAO, χ^2, Significance(σ)
      • (2pcf, 72.05, 32.49, 39.56, 6.29)
      • (3pcf, 70.21, 32.2, 38.01, 6.17)
      • (4pcf, 4.99, 1.33, 3.66, 1.91)
  • 1) Using N-body
    • In this plot we used multidark Pathcy Mock which is not full N-body.
    • So, we are going to use fully Nbody, gadget 4.
    • (Before, we compared Abacus(N-body) and Pinocchio(LPT) but we cannot compare them with observation because cosmological parameter of Abacus is fixed.
  • 2) Using jackknife error
    • C_ij → (eq.1)
    • μ_i → (eq.2)
    • Ref) Why your model parameter confidences might be too optimistic - unbiased estimation of the inverse covariance  matrix, https:// arxiv.org/pdf/astro-ph/0608064.pdf

17:30 Dr.Sabiu's Report

Speaker: Dr Cristiano Sabiu (University of Seoul)

17:45 → 17:55 Discussion