(Proto-)Clusters of Galaxies @z>1.5: an X-ray view Stefano Ettori INAF-OA / INFN Bologna XLSSC122 @z1.99 (Mantz+16)
(Proto-)Clusters of Galaxies @z>1.5: an X-ray view Two issues are relevant to the X-rays: • Detection of the ICM • Characterization of its properties 1000 Entropy profile Pure gravitation With AGN and supernova heating 100 10 100 1000 Radius (kpc)
Chandra view of high-z clusters Santos+08, 10
An example: RXJ1252, z=1.235
An example: RXJ1252, z=1.235
z=0.81 z=0.81 Gas density from the deprojected S b ~int( ε dl) ∫ M gas ( < r ) = µ m u n gas ( r ) dV M tot ( < r ) ∝− r T gas ( r ) d ln( n gas T gas ) d ln r z=1.26 z=1.26
Gas temperature profiles @z>1 z=0.83-1.24 Amodeo+16 on the c-M-z relation
The entropy of ICM: K = P ρ -5/3 ∝ T n e -2/3 (keV cm2) • Entropy distribution in ICM determines the cluster ʼ s 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 cluster ʼ s 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.
(Proto-)Clusters of Galaxies @z>1.5: an X-ray view • 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 / R 3 ~ < ρ > ~ Δ ρ cr (z) ~ H z 2 H z ~ (1+z) 1.4 (@z>1.5) ü From virial theorem/HEE: M / R ≈ T & h z M ∝ T 3/2 ü Assuming brehmsstrahlung emission & ρ DM ≈ n gas , 2 Λ (T) dV ≈ n gas 2 T 1/2 R 3 ∝ f gas 2 T 2 ∝ f gas 2 M 4/3 L ≈ ∫ n gas -1 L ∝ (h z M) 4/3 h z -1 L ∝ T 2 h z
Evolution of the X-ray scaling laws Reichert et al. 11 Dashed (solid) line: expected (best-fit) relation
Evolution of the X-ray scaling laws Reichert et al. 11 Dashed (solid) line: expected (best-fit) relation
Evolution of the X-ray scaling laws • No evolution, apart from self-similar expectations , is observed in M-T & M gas -T & L-Y The normalization in M – T/Y X for nearby systems is lower (by ~20%) than the one predicted from simulations including cooling & galaxy feedback. • 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 R 200 is measured higher in systems at higher redshift) SN/AGN feedback from SAM • eROSITA needs SLs to connect 10 5 High-z preheating+cooling Gravitational heat only (only 2% with T; ~100 @z>1.5) X-ray detected GCs to their mass ¡
Cluster Surveys: eROSITA (Merloni+12, Pillepich+12, Borm+14)
The Athena Observatory Willingale et al, 2013 arXiv1308.6785 L2 orbit Ariane V Mass < 5100 kg Power 2500 W 5 year mission Silicon Pore Optics: 2 m 2 at 1 keV 5 arcsec HEW Focal length: 12 m Sensitivity: 3 10 -17 erg cm -2 s -1 X-ray Integral Field Unit: Δ E: 2.5 eV Wide Field Imager: Field of View: 5 arcmin Δ E: 125 eV Operating temp: 50 mk Field of View: 40 arcmin High countrate capability Barret et al., 2013 arXiv:1308.6784 Rau et al. 2013 arXiv1307.1709
The first Deep Universe X-ray Observatory Athena+ has vastly improved capabilities compared to current or planned facilities, and will provide transformational science on virtually all areas of astrophysics 10000 10000 Athena+ XIFU ASTRO-H SXS 1000 Chandra HETG x ~15 E ff ective area (cm 2 ) E ff ective area (cm 2 ) XMM-Newton RGS 100 ¡x ¡ASTRO-‑H ¡ 100 1000 10 XMM-Newton EPIC PN Athena+ WFI 1 1 10 1 10 Energy (keV) Energy (keV) Athena+ (goal) 1 Athena+ eROSITA Grasp (m 2 deg 2 ) 0.1 ROSAT PSPC XMM-pn 0.01 Astro-H SXI Suzaku XIS NuSTAR Chandra ACIS-I Swift XRT 0.001 100 10 1 Half Energy Width (arcsec)
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 formation and evolution of clusters and groups of galaxies How and when was the energy contained in the hot intra-cluster medium generated? Ettori+15 How does ordinary matter assemble into the large-scale structures that we see today?
The formation and evolution of clusters and groups of galaxies How and when was the energy contained in the hot intra-cluster medium generated? Pointecouteau, Reiprich et al., 2013 arXiv1306.2319 z =2 z =1 1000 1000 Entropy profile Entropy profile Pure gravitation Pure gravitation Entropy With AGN and With AGN and supernova supernova heating heating 100 100 Athena+ Simulation 10 10 100 100 1000 1000 Radius (kpc) Radius (kpc) 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>10 15 M ¤ in the observable Universe (using Tinker+08 mass function; Churazov+16) Number of objects with M 500 /M ¤ > 5e13 (solid; >1e14 dashed) : 1900 (WMAP9; 5000 using Planck13) are expected at z>2.5 (full sky; 1 per 22 deg 2 ; 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 M 500 ~5e13 Msun? Reiprich et al, supporting paper to Athena’s WP
How does it appear a z~2.5 object with M 500 ~5e13 Msun? For the planned multi-tiered survey (4*1 Ms +20*300ks +75*100ks +250*30ks ~78 deg 2 over 5 years) ~50 (5) groups @z>2 (2.5) Reiprich et al, supporting paper to Athena’s WP
Properties of a object with M 500 ~5e13 Msun
Properties of a object with M 500 ~5e13 Msun @z=2.5, 1 Msec XIFU ε T ~10%
Properties of a object with M 500 ~5e13 Msun
Properties of a object with M 500 ~5e13 Msun
(Proto-)Clusters of Galaxies @z>1.5: an X-ray view • 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
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