Journal Club 2017/10/16

Transcription

1 Journal Club 2017/10/16 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy [arxiv: ] Anthony M. Young, Liliya L. R. Williams, Jens Hjorth [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions [arxiv: ] Álvaro A. Orsi, Raúl E. Angulo

2 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy Introduction Galaxies are hosted by dark-matter halos and halos sometimes merge Dynamical state of dark matter and baryon have information about merging history. Elliptical galaxies at z~2 are more compact than those at z~0 Credit : Deborch Byrd in SCIENCE WIRE

3 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy In this paper they Method Use Illustris-1 Simulation(hydrodynamic N-body) Select one halo(halo 138) and also Select some DMparticles(set A) Analyze their evolution history focusing on their E and L " distribution

4 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy Focus on 3 phases Phase 1 Phase 2 Phase 3 Halo Major merger Minor merger Accretion Condition of Set A Merging as smaller halo Merging as main halo Main halo

5 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy All DM Initial Set A All DM Final Set A Phase1 log Phase2 Phase3 E

6 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy Set A Phase 1 Phase 2 Phase 3 Median(f $ ) Median(f & ')

7 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy z=1.47(during Phase 1) z=0(now) blue:set A ) particle (Main halo Set A) green:set A particle All DM vs theory(best-fit) All DM vs Set A

8 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy z=0(now) DM and baryon are not well mixed. Distribution of DM alone is much closer to theoretical model than that of all particles. All particle vs theory Phase 2 Set A N 789: and N ;97 are defined over energy range they consider. The most bound DM particles retain most of their energy, and so as to star.

9 [1]:Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy r 8 is spherically averaged radius at which the density of baryons is equal to that of DM

10 [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions Introduction Correlation function of galaxies is important for cosmology To estimate correlation function accurately, redshiftspace distortion effect should be considered Main target galaxies of Spectroscopic observation are Luminous Red Galaxies Emission Line Galaxies Credit: Nasa, Alma

11 [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions In this paper they Method Use Millennium-XXL simulation(dmonly Nbody simulation) correspond galaxy to halo by L-Galaxy(semi-analytical model) Analyze galaxy s peculiar velocity and make models to correct redshift-space distortion effects for LRG and ELG separately

12 [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions Red : all galaxies of each type(lrg or ELG, Centrals or Satellites, or Mass range of host halo) Green : their samples of each type

13 [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions Black solid line: Double Gauss model

14 [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions LRG satellite s host halos are more massive than ELG ELG satellites are populating in outskirt and now infalling

15 [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions Model A Model B Only σ is a fitting parameter f 798 and σ are fitting parameters Model C (1 f 798 ) +f 798 δ? 0 α, f 798, v :,C, v :,", σ F,C, σ F," are fitting parameters

16 [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions Gray line show P(v IJ7 )=δ? 0, i. e.not corrected Blue and Red lines are model C. The difference between Gray and Red points is significant The difference between points and color lines(modelc) is O(1).

17 [2]:The impact of galaxy formation on satellite kinematics and redshift-space distortions Model C Gets good agreement.