X‐ray properties of galaxy clusters and groups from a cosmological hydrodynamical simulation

By Stefano Borgani, Giuseppe Murante, Volker Springel, A. Diaferio, Klaus Dolag, L. Moscardini, G. Tormen, Luca Tornatore, P. T. Astr.Dept., Trieste and 9 more. 2003

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We present results on the X-ray properties of clusters and groups of galaxies, extracted from a large cosmological hydrodynamical simulation. We used the TREE+SPH code GADGET to simulate a concordance A cold dark matter cosmological model within a box of 192 h -1 Mpc on a side, 480 3 dark matter particles and as many gas particles. The simulation includes radiative cooling assuming zero metallicity, star formation and supernova feedback. The very high dynamic range of the simulation allows us to cover a fairly large interval of cluster temperatures. We compute X-ray observables of the intracluster medium (ICM) for simulated groups and clusters and analyse their statistical properties. The simulated mass-temperature relation is consistent with observations once we mimic the procedure for mass estimates applied to real clusters. Also, with the adopted choices of Ω m = 0.3 and σ 8 = 0.8 for matter density and power spectrum normalization, respectively, the resulting X-ray temperature functton agrees with the most recent observational determinations. The luminosity-temperature relation also agrees with observations for clusters with T ≥ 2 keV. At the scale of groups, T ≥ 1 keV, we find no change of slope in this relation. The entropy in central cluster regions is higher than predicted by gravitational heating alone, the excess being almost the same for clusters and groups. We also find that the simulated clusters appear to have suffered some overcooling. We find f * ≃ 0.2 for the fraction of baryons in stars within clusters, thus approximately twice as large as the value observed. Interestingly, temperature profiles of simulated clusters are found to increase steadily toward cluster centres. They decrease in the outer regions, much like observational data do at r ≥ 0.2r vir , while not showing an isothermal regime followed by a smooth temperature decline in the innermost regions. Our results thus demonstrate the need for yet more efficient sources of energy feedback and/or the need to consider additional physical process which may be able to further suppress the gas density at the scale of poor clusters and groups, and, at the same time, to regulate the cooling of the ICM in central regions.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

IMPACT OF CLUSTER PHYSICS ON THE SUNYAEV–ZEL'DOVICH POWER SPECTRUM (2010, result): “A10 found there to be a good agreement between the observed profiles and those measured from the hydrodynamical simulations of Borgani et al. (2004); Nagai et al. (2007a) and Piffaretti & Valdarnini (2008).”
Galaxy-cluster gas-density distributions of the Representative XMM-Newton Cluster Structure Survey (REXCESS) (2008, methodology): “The scaling properties of the gas density profiles appear to be in broad agreement with those of simulated cluster samples (Borgani et al. 2004) at intermediate radius, with a slightly flatter slope in the outer regions.”
Virial Scaling of Massive Dark Matter Halos: Why Clusters Prefer a High Normalization Cosmology (2007, methodology): “Ettori et al. (2006) analyzed the 4803 particle GADGET models of Borgani et al. (2004) plus additional resimulations and found that, while the overall baryon fraction within r200 is relatively robust, ¼ 0:94 0:03, the hot gas fraction f̂ICM is sensitive to physical treatment, varying by 40% over…”
A comparison of weak-lensing masses and X-ray properties of galaxy clusters (2007, background): “The net result is a increased temperature, or lower normalization (e.g. Voit et al. 2002; Borgani et al. 2004).”
Planck intermediate results: V. Pressure profiles of galaxy clusters from the Sunyaev-Zeldovich effect (2012, unknown): “The three shaded areas mark the dispersions about the average proﬁles for three samples of simulated clusters: in blue, the simulations from Borgani et al. (2004), Nagai et al. (2007a) and Pi ﬀ aretti & Valdarnini (2008), which were used in A10 to derive the universal pressure proﬁle together with…”
ERRATUM: “CHANDRA SAMPLE OF NEARBY RELAXED GALAXY CLUSTERS: MASS, GAS FRACTION, AND MASS–TEMPERATURE RELATION” (2006, ApJ, 640, 691) (2005, background): “T relation is also in good agreement with those derived from recent high-resolution numerical simulations (e.g., Borgani et al. 2004) that attempt to model nongravitational processes in the ICM (radiative cooling, star formation, and feedback from supernovas).”
X-Ray and Sunyaev-Zel’dovich Effect Measurements of the Gas Mass Fraction in Galaxy Clusters (2006, unknown): “…Chandra observations and numerical simulations indicate that the β-model is not a good description in the outskirts (r > 1—1.5r2500) of clusters (Borgani et al. 2004; Vikhlinin et al. 2005); to avoid biases associated with this effect, we compute masses enclosed within r2500, the radius at…”
Formation of Galaxy Clusters (2012, background): “The overall shape of the profile at these large radii is reproduceby simulations including a wide range of physical processes, including non-radiatives mulations (e.g., Borgani et al. 2004; Loken et al. 2002; Nagai, Kravtsov & Vikhlinin 2007).”
LoCuSS: comparison of observed X-ray and lensing galaxy cluster scaling relations with simulations (2008, methodology): “The normalization of the X-ray mass-observable relations is lower than the one from simulations (M−YX and M−Mgas in Nagai et al. 2007b; M−T and Lbol−M in Borgani et al. 2004, emission weighted temperature) by (1) 18±4 per cent for M−YX, (2) 13 ± 4 per cent for M−Mgas, (3) 19 ± 6 per cent for M−T , a”
Radial temperature profiles for a large sample of galaxy clusters observed with XMM-Newton (2008, background): “…outer regions are rich of information and interesting to study, because clusters are still forming there by accretion (e.g. Tozzi et al. 2000; Borgani et al. 2004); moreover, far from the core it is easier to compare simulations with observations, because feedback eff cts are less important…”
MASSIVE HALOS IN MILLENNIUM GAS SIMULATIONS: MULTIVARIATE SCALING RELATIONS (2009, methodology): “The mass-weighed temperature, Tm, a useful probe of the hydrodynamic state of the ICM, is known to have small scatter with respect to mass in simulations (Evrard et al. 1996; Bryan & Norman 1998; Borgani et al. 2004).”
Improved constraints on dark energy from Chandra X-ray observations of the largest relaxed galaxy clusters (2007, background): “…range of such variation is constrained by numerical simulations or other, complementary data (Eke et al. 1998; Bialek, Evrard & Mohr 2001; Muanwong et al. 2002; Borgani et al. 2004; Kay S. et al. 2004; Ettori et al. 2004, 2006; Kravtsov, Nagai & Vikhlinin 2005; Nagai, Vikhlinin & Kravtsov 2007a).”
The structural and scaling properties of nearby galaxy clusters. II. The M-T relation (2005, background): “Using this temperature definition at δ = 500, the normalisation of Borgani et al. (2004) is now too high by about 12–20 per cent, the normalisation found by Voit et al. (2002) is marginally too low and the normalisation found by Muanwong et al. (2002) at δ = 200 is 30 per cent too high (Fig.”
A Fitting Formula for the Merger Timescale of Galaxies in Hierarchical Clustering (2007, background): “…known that current hydrodynamic simulations suffer from the so called ’overcooling’ problem, i.e. the gas at the core of massive dark matter halos cools too rapidly resulting in too massive central galaxies compared to observations (e.g., Borgani et al. 2004; Saro et al. 2006; Naab et al. 2007).”
On the efficiency and reliability of cluster mass estimates based on member galaxies (2006, methodology): “We refer to Borgani et al. (2004) for a complete description of this simulation and of the cluster identification procedure.”
CHANDRA STUDIES OF THE X-RAY GAS PROPERTIES OF GALAXY GROUPS (2008, methodology): “The group temperature profiles actually agree more with simulations (e.g., Loken et al. 2002; Borgani et al. 2004), which generally have problems explaining the flat temperature profiles of clusters at 0.15r500−0.3r500 (e.g., Borgani et al. 2004).”
The case for AGN feedback in galaxy groups (2009, result): “These results are consistent with the findings of several previous studies based on cosmological simulations, including Borgani et al. (2004) and Nagai et al. (2007).”
Smoothed Particle Hydrodynamics in Astrophysics (2010, background): “The situation is better for clusters of galaxies, where the most recent SPH simulations have been quite successful in reproducing the primary scaling relations that are observed (Borgani et al., 2004; Puchwein, Sijacki & Springel, 2008; McCarthy et al., 2010).”
Wide-Field InfrarRed Survey Telescope-Astrophysics Focused Telescope Assets WFIRST-AFTA 2015 Report (2015, methodology): “…et al. 2000, Ferrarese & Merritt 2000) and (2) numerical simulations show that star formation in the most massive galaxies must be suppressed by processes more powerful than supernovae and stellar winds in order to simulate galaxies resembling those we actually observe (e.g. Borgani et al. 2004).”