1. MACRO – the Simulated Galaxy Cluster Project : What can we suggest?
Cui Weiguang*, Power Chris, Borgani Stefano, et al.
@NAOC
20/10/2016
Cui et al. 2016a (MNRAS, 456, 2566),
Cui et al. 2016b (arXiv: , accepted by MN)
Cui et al. 2016c (to be submitted)
1 It is a great pleasure to come and visit here
Today I am going to talk about my recent work on a galaxy cluster sample.
Physics – designed experiment -> astronomy is driving by observation -> theory is used to explain what we see, how can one prove or disprove the theory? simulation is the only lab

2. Introduction The nature of galaxy / the Universe X-ray SZ Optical
Big picture!
Not the same galaxy cluster!!
Radio and other bands are not included in here
The simulated galaxy / universe
Physical models:
N-body simulations + SAM/HOD
Hydro-dynamical simulations

3. Introduction Hydro-dynamical simulations
Simulated galaxies with all physical properties
Hydro-dynamical simulations
Self-consistent in model and gravity solving
Mock observations through physical processes
Introducing details of what we do
Consistency properties -> can they give the same results? We have theoretical result as a base line
What can we learn through these multi-wavelength observations?

4. What in this talk The MACRO* cluster sample Post processing
What can we suggest/learn?
MACRO the name abbreviate alphabet
As I said before the mocking park plays important role!

5. MACRO: the cosmology simulations
The cosmological simulation parameters:
Parameters: Ωm = 0.24; Ωb = 0.04; h = 0.72; σ8 = 0.8; ns = 0.96.
Simulation details: 2*10243 particles; Boxsize 410 Mpc/h; softening length 7.5 kpc/h
The versions of the simulation:
DM: dark matter only
CSF: gas cooling, star formation and SN feedback
AGN: also with AGN feedback
More details can be found in Cui et al & 2014

6. MACRO: cluster selection
Halos are identified with the spherical overdensity (SO) algorithm (PIAO, Cui et al )
From DM run, we select out ~180 halos, which has M200 > 2.0x1014 M⊙/h
Using the unique dark matter particle ID, all the halos from the CSF and AGN runs are matched to these selected halos from the DM run.

7. MACRO: mock process
Optical image: star particles are treated as a simple stellar population. With the synthetic code (Cui et al. 2011, based on BC03), we produced the SDSS u, g, r band images of these clusters.
X-ray Emission: PHOX code, X- ray photons are obtained from the bremsstrahlung continuum plus metal emission lines spectrum calculated for every gas particle (Biffi et al. 2012, 2013). The realistic image has an exposure time of 50 ks and convolved with the response matrices of Chandra ACIS- S detector.
SZ signal: SZ-pack (Chluba, et al 2012, 2013) is used to calculate the thermal and kinematic SZ effect. Both explicit numerical integration as well as approximate representation of the SZ signals can be obtained.
More, radio signal is in development.

8. MACRO: sample Up panels: dynamical un-relaxed
Bottom panels: dynamical relaxed

9. MACRO: what to do? Galaxy cluster center
Galaxy cluster dynamical states

10. MACRO I: The centre
Theoretical definitions: minimum potential (most bound particle) position, maximum density position(estimation methods: SPH, Voronoi tessellation, iterative centre of mass).
Optical centre: the position of the BCG.
X-ray centre: Centroid, X-ray peak.
Cui et al. 2016a MNRAS, 456, 2566

11. Differences between two theoretical centres
MACRO I: The centre
Differences between two theoretical centres
Minimum potential center agrees with maximum density center
Cui et al. 2016a MNRAS, 456, 2566

12. Optical and X-ray centres
MACRO I: The centre
Optical and X-ray centres
Optical
centre
Optical is better than X-ray for identifying cluster center!
X-ray
centre
Cui et al. 2016a MNRAS, 456, 2566

13. MACRO II : The dynamical state
The classification of the cluster dynamical state
Relaxed or Unrelaxed?
Theoretical approaches: virial ratio, centre of mass offset, subhalo mass fraction (e.g. Neto et al. 2007).
Optical methods: Based on luminosity map of the cluster, the asymmetry, the ridge flatness and the normalized deviation (e.g. Wen et al. 2013)
X-ray methods: Power ratio, centre of luminosity/mass offset (e.g. Bohringer et al. 2010), Morphology method: Rasia, et al ; peakiness, alignment, symmetry (Mantz et al. 2015)
Paper II
Paper III
Cui et al. 2016b, MNRAS, accepted

14. MACRO II: The dynamical state
Xray luminosity function

15. MACRO II: The dynamical state

16. MACRO II: The dynamical state
Theoretical approaches
Substructure mass fraction
The subhalo is identified by the SubFind program。
The subhalo mass fraction is defined as the total subhalo mass (excluded the main subhalo) divided by the halo mass.

17. MACRO II: The dynamical state

18. MACRO II: The dynamical state
The radial profile
Cui et al. 2016b

19. MACRO II: The dynamical state
The Baryon effects
The change of \eta (for baryon effects) is mainly caused by the deeper gravitational potential.
Cui et al. 2016b

20. MACRO II: The dynamical state
The relations
~70%
~35%
(~75% cross
identified)
Eta - zeta relation can be used in observation to infer the theoretical dynamical predictions.
Observation predicts that the relaxation fraction is ~30%, which agrees more with the restricted limitations. Neto et al ’s parameters give a relaxation fraction ~70%.
Cui et al. 2016b

21. MACRO III: a comparison of dynamical state finding methods
Primordial results
Agreed to the Zhang 2014 and Yang 2010 that SZ tend to be located at minimum potential and to have less impact on the cluster dynamical states.

22. MACRO III: a comparison of dynamical state finding methods
Primordial results
Wen’s method mainly deepened on the BCG, which is apparently more massive in the simulation.
X-ray
Rasia et al. 2012
Optical
Wen & Han 2013

23. Summary The cluster centre: The cluster dynamical state:
The potential centre and density centre are not fully consistent.
Optical selected BCG centre traces the potential centre better than the X-ray centre.
The cluster dynamical state:
The η parameter from the CSF/AGN runs is ∼ 10 per cent lower than from the DM run.
No clear bimodal distribution between the relaxed and un-relaxed clusters.
The correlation between η and ζ suggests a new way in observation of calculating η parameter, thus the cluster dynamical state.
The relaxation fraction is relying on the parameter limitations, but is un-affected by baryons.
Seek collaborations more than exhibitions.