(proto-)clusters of galaxies @z>1.5: an x-ray view

Stefano EttoriINAF-OA / INFN Bologna

(Proto-)Clusters of Galaxies @z>1.5: an X-ray view

XLSSC122 @z1.99 (Mantz+16)


Two issues are relevant to the X-rays:

•  Detection of the ICM •  Characterization of its properties

Entropy profile Pure gravitation

With AGN and

supernova heating

Radius (kpc)

1000

100

10 100 1000

Chandra view of high-z clusters

Santos+08, 10

An example: RXJ1252, z=1.235

z=0.81

z=1.26

Gas density from the deprojected Sb~int(ε dl)

Mtot (< r)∝− r Tgas (r)d ln(ngas Tgas )

d ln r€

Mgas(< r) = µmu n∫ gas(r) dV

Gas temperature profiles @z>1

Amodeo+16 on the c-M-z relation

z=0.83-1.24

The entropy of ICM: K = Pρ-5/3 ∝ T ne

-2/3 (keV cm2)

•  Entropy distribution in ICM determines the clusterʼs equilibrium structure high-K gas floats, low-K gas sinks; ICM convects until its isentropic surface coincide with equipotential surface of DM potential • Entropy distribution retains information about clusterʼs thermodynamic history • Heating and cooling change K more than T

Evolution of the K profile

Ghirardini+ in prep

Evolution of the K profile

Ghirardini+ in prep.


•  For a given mass, scaling relations in the LCDM predict that the clusters formed at larger redshift are hotter / denser and therefore more luminous in X-rays than their local z~0 counterparts.

•  This effect overturns the decrease in the observable X-ray flux so that it does not decrease at z>1, similar to the SZ signal.

•  Provided that scaling relations remain valid at larger redshifts, X-ray surveys will not miss massive clusters at any redshift, no matter how far they are.

Evolution of the X-ray scaling laws ü  In the absence of non-gravitational physical processes,

ICM evolves in the DM potential following the (pseudo-; see Diemer+12) evolution of the associated overdensity:

M / R3 ~ <ρ> ~ Δ ρcr(z) ~ Hz2

Hz ~ (1+z)1.4 (@z>1.5)

ü  From virial theorem/HEE: M / R ≈ T & hz M ∝ T3/2

ü  Assuming brehmsstrahlung emission & ρDM ≈ ngas,L ≈ ∫ ngas

2 Λ(T) dV ≈ ngas2 T1/2 R3 ∝ fgas

2 T2 ∝ fgas2 M4/3

hz-1 L ∝ (hz M)4/3

hz-1 L ∝ T2

Dashed (solid) line: expected (best-fit) relation

Evolution of the X-ray scaling laws Reichert et al. 11

•  No evolution, apart from self-similar expectations, is observed in M-T & Mgas-T & L-YThe normalization in M – T/YX for nearby systems is lower (by ~20%) than the one predicted from simulations including cooling & galaxy feedback.

High-z preheating+cooling

•  Negative evolution in L-T: i.e. a slight decrease in L for given T at higher z is observed (when cores are not excised; the entropy at 0.1 R200 is measured higher in systems at higher redshift)

•  eROSITA needs SLs to connect 105 (only 2% with T; ~100 @z>1.5) X-ray detected GCs to their mass

SN/AGN feedback from SAM

Gravitational heat only

Evolution of the X-ray scaling laws

Cluster Surveys: eROSITA (Merloni+12, Pillepich+12, Borm+14)

The Athena Observato ry

L2 orbit Ariane V Mass < 5100 kg Power 2500 W 5 year mission

X-ray Integral Field Unit: ΔE: 2.5 eV Field of View: 5 arcmin Operating temp: 50 mk

Wide Field Imager: ΔE: 125 eV Field of View: 40 arcmin High countrate capability

Silicon Pore Optics: 2 m2 at 1 keV 5 arcsec HEW Focal length: 12 m Sensitivity: 3 10-17 erg cm-2 s-1

Rau et al. 2013 arXiv1307.1709 Barret et al., 2013 arXiv:1308.6784

Willingale et al, 2013 arXiv1308.6785

100 x ASTRO-‐H

The f i r s t Deep Un iverse X- ray Observato ry Athena+ has vastly improved capabilities compared to current or planned facilities,

and will provide transformational science on virtually all areas of astrophysics

Athena+ XIFUASTRO-H SXSChandra HETGXMM-Newton RGS

Effec

tive

area

(cm

2 )

1

10

100

1000

10000

Energy (keV)1 10

XMM-Newton EPIC PNAthena+ WFI

x ~15

Effec

tive

are

a (c

m2)

1000

10000

Energy (keV)1 10

XMM-pn

eROSITA

Athena+

Athena+ (goal)

Chandra ACIS-I

ROSAT PSPC

NuSTAR

Swift XRT

Suzaku XISAstro-H SXI

Gra

sp (m

2 de

g2 )

0.001

0.01

0.1

1

Half Energy Width (arcsec)110100

Role of Athena By 2030s, the cosmological parameters describing the evolution of the Universe as a whole will likely be tightly constrained (thanks to Euclid & eROSITA).

Progress will have been made in understanding how structure formation works via the study of the galaxy distribution and evolution (Euclid, LSST).

However, major astrophysical questions related to the formation and the evolution of galaxy clusters will still remain: •  Interplay btw central BH / galaxy / gas•  Processes driving metal & energy enrichment of the ICM•  How & when first collapsed groups appear

The fo rmat ion and evo lu t ion o f c lus te r s and g roups o f ga lax ies

How and when was the energy contained in the hot intra-cluster medium generated?

How does ordinary matter assemble into the large-scale structures that we see today?

Ettori+15

Pure gravitation

With AGN and supernova

heating

Entropy profile

Radius (kpc)

1000

100

10 100 1000

The fo rmat ion and evo lu t ion o f c lus te r s and g roups o f ga lax ies

How and when was the energy contained in the hot intra-cluster medium generated?

z=1 Entropy profile Pure gravitation

With AGN and supernova

heating

Radius (kpc)

1000

100

10 100 1000

z=2

Entr

op

y

Athena+ Simulation

Pointecouteau, Reiprich et al., 2013 arXiv1306.2319

How does ordinary matter assemble into the large-scale structures that we see today?

The most massive clusters at high-z

There are ~50 clusters with M>1015 M¤ in the observable Universe (using Tinker+08 mass function; Churazov+16)

Number of objects with M500/M¤ > 5e13 (solid; >1e14 dashed): 1900 (WMAP9; 5000 using Planck13) are expected at z>2.5 (full sky; 1 per 22 deg2; Reiprich+)!

The most massive clusters at high-z

Accretion history from!Van den Bosch+14!

How does it appear a z~2.5 object with M500~5e13 Msun?

Reiprich et al,supporting paper to Athena’s WP

How does it appear a z~2.5 object with M500~5e13 Msun?

Reiprich et al,supporting paper to Athena’s WP

For the planned multi-tiered survey (4*1 Ms +20*300ks +75*100ks +250*30ks ~78 deg2 over 5 years)

~50 (5) groups @z>2 (2.5)

Properties of a object with M500~5e13 Msun


@z=2.5, 1 Msec XIFU εT~10%


•  For a given mass, scaling relations in the LCDM predict that the clusters formed at larger redshift are hotter / denser and therefore more luminous in X-rays than their local z~0 counterparts.

•  Provided that scaling relations remain valid at larger redshifts, X-ray surveys will not miss massive clusters at any redshift, no matter how far they are.

•  Athena will resolve ICM properties up to z~2, detecting the first collapsed structure at z~2.5

(proto-)clusters of galaxies @z>1.5: an x-ray view

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