The Distribution of Stellar Mass in Galaxy Clusters since z≈1

Remco van der Burg CEA Saclay, France Adam Muzzin, Henk Hoekstra, Monique Arnaud, Gabriel Pratt, Jean-Baptiste Melin, Hervé Aussel, Gillian Wilson, Chris Lidman, Howard Yee, Sean McGee, Michael Balogh, Cristóbal Sifón SpARCS-1613, z=0.87

The Distribution of Stellar Mass in Galaxy Clusters since z≈1

Remco van der Burg CEA Saclay, France Adam Muzzin, Henk Hoekstra, Monique Arnaud, Gabriel Pratt, Jean-Baptiste Melin, Hervé Aussel, Gillian Wilson, Chris Lidman, Howard Yee, Sean McGee, Michael Balogh, Cristóbal Sifón Abell 85, z=0.05

“Ultra-Diffuse Galaxies”

!   Concentration: !   Beware of Pseudo-evolution

!   Presence of Baryons can alter Substructure Distribution

NFW Profiles of Dark Matter Haloes

(e.g. Nagai & Kravtsov 2005)

Mh≈1014 M¤

Mh≈1012 M¤

Navarro, Frenk, White (1997)

Moore et al. 1999

What is the radial distribution of stellar mass in high mass haloes?

(e.g. Diemer+13, Wetzel+15)

Observed Stellar Mass Distributions !   Stellar Matter also well described by NFW profile

!   Concentration of stars (observations) is consistent with the concentration of the dark matter in similar haloes (simulations)

? Lin+2004

This is a K-band luminosity profile

These are number density profiles

Different studies not homogeneous + unknown what happens at high z

!   60 clusters at 0.05 < z < 0.26 !   Canadian-Cluster-Comparison Project

!   Multi-Epoch Nearby Cluster Survey

! ugri-band photometry

!   ∼10,000 spectroscopic members

Two Galaxy Cluster Samples !   10 clusters at 0.86 < z < 1.34 from 42

deg2 SpARCS/SWIRE survey !   Gemini CLuster Astrophysics Spectroscopic

Survey (GCLASS)

! ugrizJKs + 4IRAC band photometry

!   457 spectroscopic members

vdBurg+13 vdBurg+14

vdBurg+15

(Sifón+2015)

(Muzzin+2012)

z≈0.15 Stellar Mass Distribution

!   NFW profile (c≈2) fits ensemble distribution for radii R > 0.10 R200

!   Significant excess in the centre, ≈1011 M⊙ per cluster !   No dependence on: redshift, halo mass, BCG stellar mass, cluster

central entropy, richness

vdBurg+15

z≈0.15 Stellar Mass Distribution

!   NFW profile (c≈2) fits ensemble distribution for radii R > 0.10 R200

!   Generalized NFW profile gives a better fit overall !   Inner slope ρ∝ r−1.63±0.10

vdBurg+15

Inner slope ρ∝r−1.6

Generalized NFW (free inner slope)

z≈0.15 Stellar Mass Distribution

!   NFW profile (c≈2) fits ensemble distribution for radii R > 0.10 R200

!   Reasonable agreement with dark matter distribution (N-body simulations)

z≈1 Stellar Mass Distribution vdBurg+14

!   Well fitted by NFW profile with concentration parameter c≈7

!   Stellar Mass at z=1 significantly more concentrated than !   Dark matter in N-body simulations

!   Dynamically-estimated average mass profile cNFW=4.0

!   Likely descendants at lower redshift (z=0.15)

+1.0 -0.6

(Biviano+2016)

Observed Evolution !   Complications:

!   NFW profile no good fit to low-z at small radii

!   Pseudo-evolution complicates interpretation

!   Cluster samples are linked progenitors-descendants !   Compare profiles on the same physical scale

!   Orange region ≈6⨉1011 M☉: consistent with BCG growth

!   Clusters accrete stellar mass onto the outskirts

Physical distance

BCG+ICL growth

Outside Growth

(e.g. Diemer+13, Wetzel+15)

Observed Evolution

!   Inner ~400kpc of the stellar mass distribution already present in the centre by z=1

!   Different from evolution of dark matter distribution in N-body simulations

cf. Dutton & Macciò 2014

cf. talk by Chris Lidman on BCG growth

!   So far limited sample at high-z (z~1, 10 systems)

!   Now studying 22 of the most massive clusters at 0.5<z<0.7, selected based on Sunyaev-Zel’dovich effect with Planck

Outlook- Observations

With Monique Arnaud, Hervé Aussel, Gabriel Pratt, Jean-Baptiste Melin, Håkon Dahle, Amandine Le Brun, Jessica Démoclès, Iacopo Bartalucci, …

PLCKG73.3+67.5, z=0.61

cf. Monique’s talk on Friday

Total stellar mass distribution

An observational study of the build-up of stellar mass in galaxy clusters by combining 2 samples which are progenitors/descendants:

!   At z=0.15, significant central excess (for R < 0.10 R200) compared to best-fitting NFW profile

!   Naïve comparison of NFW concentrations suggests a dramatic evolution since z=1

!   Comparison on the same physical scale indicates inside-out growth of the stellar mass distribution since z=1 !   Stellar material is already present in the centre (R < 0.4 Mpc)

vdBurg+15

How about different galaxy types?

47 Ultra-Diffuse Galaxies (UDGs) in the Coma cluster van Dokkum+2015

•  reff>1.5 kpc •  <μ(r,reff)> ≈25 mag arcsec-2

How can UDGs survive the harsh dynamical environment of galaxy clusters?

In the following months:

How can UDGs survive the harsh dynamical environment of galaxy clusters?

!   Models rely on quantitative observational constraints

!   Only Coma cluster studied, and some examples in Virgo and Fornax

!   Early studies not systematic, nor objective/reproducible

A systematic study of UDGs in 8 of the low-z clusters

!   Image simulations to quantify completeness

!   Tightened selection criteria (SExtractor & GALFIT) to keep purity high

!   Estimate background statistically using “empty” fields

!   2500 selected in 8 clusters, 600 selected in 4 reference fields

vdBurg+16b

What are their physical properties? Almost all on the red sequence

r eff [k

pc]

Rec

over

y ra

te

Radial distribution of UDGs

! Einasto parameters different from typical dark matter halo

!   Where does this distribution originate from?

Radial distribution of UDGs

!   Roughly follows dynamically old population in outskirts

Total stellar-mass-weighted distribution of quiescent galaxies

Radial distribution of UDGs

!   They can exist down to 300kpc (3D radius, before projection)

!   They have to be centrally dark-matter dominated !   Are they “failed Milky-Ways”?

Total stellar-mass-weighted distribution of quiescent galaxies

(van Dokkum+2015)

Radial distribution of “normal” dwarfs

!   “Normal” dwarfs with 0.5< reff [kpc] <1.0 and same luminosities as UDGs, exist down to ~100kpc from the cluster centre

UDGs Dwarfs

Roche limit for UDGs and “normal” dwarfs

!   A comparison of UDGs and more compact dwarfs with stellar masses of 108 M¤

!   Given cluster mass interior to 100kpc, one needs 4×108 M¤

within a tidal disruption radius of 2kpc for dwarfs

!   Given cluster mass interior to 300kpc, one needs 2×109 M¤

within a tidal disruption radius of 6kpc for UDGs

Two enclosed masses for 2 different populations

UDGs Dwarfs

Roche limit for UDGs and “normal” dwarfs

!   Consistent with them having similar dark-matter haloes

!   Dynamically-measured masses very high !   Working on stacked lensing mass of UDGs With Cristóbal Sífon, Henk

Hoekstra, Adam Muzzin

Abundance versus halo mass

!   Similar slope as mass-richness relation

!   Does this relation extend down to groups? And individual galaxies?

Mass measurements: Sifón+15

(Román & Trujillo 2016; Merritt+2016)

Tota

l ste

llar

mas

s An observational study of the build-up of stellar mass in galaxy clusters by combining 2 samples which are progenitors/descendants:

!   NFW concentrations suggest a dramatic evolution since z=1

!   Comparison on the same physical scale indicates inside-out growth of the stellar mass distribution since z=1 !   Stellar material is already present in the centre (R < 0.4 Mpc)

vdBurg+15 Conclusions

Ultr

a-D

iffu

se G

alax

ies

Abundance of UDGs in clusters surprising and not yet understood

!   Quantitative constraints from a systematic study in 8 clusters !   They follow dynamically old galaxies spatially, with central deficit

What are their (sub-)halo masses?

!   Abundant in each cluster, with abundance scaling with M200

Are they also abundant in groups, and in isolation?

vdBurg+16b