cluster scaling relations and mass definitions

Transcription

1 cluster scaling relations and mass definitions Andrey Kravtsov Department of Astronomy & Astrophysics Kavli Institute for Cosmological Physics The University of Chicago Abell 85 SDSS

2 Abell 85 SDSS/ Abell Chandra 85 SDSS/ Chandra

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5 The nature of scaling relations scaling relations arise from tight relations between radial profiles of various cluster quantities Example: velocity dispersion-mass correlation: Diemer, Kravtsov, More 2013

6 halo edges sharp steepening of the density profile is present in the outskirts of the fast accreting halos Diemer & Kravtsov 2014, ApJ 789, 1 cf. also Adhikari et al. 2014, PRD; More, Diemer & Kravtsov 2015, in prep. dark matter density map in two different cluster-sized halos in a slice through the center of thickness =0.15 Rvir (density is reconstructed using phase-space sheet, cf. Hahn & Abel 11)

7 what are these edges? they are formed by the recently accreted matter that passed through halo just once and has splashed back to the first apocenter. Such edge is predicted by the secondary infall models (e.g., Gunn & Gott 72; Fillmore & Goldreich 84; Bertschinger 85; Lithwick & Dalal 11; Vogelsberger et al. 11; Adhikari et al. 14) radial velocity-radius diagram and density profile predicted in such models for initial density peaks of different ellipticity (e=0 is spherically symmetric peak) splashback radial velocity matter overdensity splashback radius in units of the turnaround radius

8 the splashback radius depends on halo mass accretion rate Diemer & Kravtsov 2014, ApJ cf. also Adhikari et al. 2014, More, Diemer & Kravtsov 2015, in prep. slow accreting cluster splashback is farther out relative to Rvir fast accreting cluster splashback is closer to Rvir dark matter density map in two different cluster-sized halos in a slice through the center of thickness =0.15 Rvir

9 Similar edge exists in cluster gas density profile in hydro simulations as expected in the secondary infall models (Bertschinger 85) slope of gas density profile ratio of gas density to DM density profile radius in units of R 200mean Lau et al (arxiv/ )

10 point sources removed splashback in Abell 133 Vikhlinin et al. in prep based on 2 Msec Chandra observation splashback is quite close to R 200 indicating very high mass accretion rate (consistent with high galaxy overdensity around the cluster) clumps removed, surface brightness stretched

11 comparison of mass evolution in the inner regions of halos and total mass within splashback relatively quiet inner regions, but actively growing outer regions. (note that high mass accretion rate high rate of major mergers) thus, A133 may have a cool core in the center, but may still be actively accreting mass mass(z) normalized by virial mass at z=0 mass within Rsplashback mass within 2 NFW scale radii (~R 500 ) More, Diemer & Kravtsov 2015, in prep.

12 regions around massive cluster which should be accessible with target sensitivity of SMART-X cf. Christine Jones talk on Friday 25 Mpc observable in X-ray until now based on simulation by E. Rasia and K. Dolag

13 summary Cluster scaling relations arise from the tight relations between radial profiles of the corresponding quantities. Mass definitions are usually arbitrary and can be optimized for specific purpose (e.g., minimize scatter in the corresponding scaling relation). Beware of spurious definitional redshift factors! They have no physical meaning Clusters do have physical boundary corresponding to the splashback radius of the recently accreted matter. Expected in both dark matter and gas with radius depending on total mass accretion rate. Splashback may already have been detected in Abell 133 in gas. If true it indicates that A133 accretes at very high rates and illustrates that high mass accretion may co-exist with relatively quiet cool core. Kravtsov & Borgani 2012, ARAA Diemer, Kravtsov & More 2013, ApJ 766, 25 Diemer & Kravtsov 2014, ApJ 789, 1 Diemer, More & Kravtsov 2015, in prep. Vikhlinin et al. 2015, in prep.

14 The choice of the outer radius may matter e.g., matter density profile in the outer regions scales better with R200m, but for the inner regions R200c appears to be better log. slope profile of matter density profiles of 3.5 sigma halos at different z Diemer & Kravtsov 2014, ApJ 789, 1

15 The first derived cluster scaling relation?