The Birmingham-CfA cluster scaling project - III. Entropy and similarity in galaxy systems

By Trevor J. Ponman, A. Sanderson, A. Finoguenov. 2003

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We examine profiles and scaling properties of the entropy of the intergalactic gas in a sample of 66 virialized systems, ranging in mass from single elliptical galaxies to rich clusters, for which we have resolved X-ray temperature profiles. Some of the properties we derive appear to be inconsistent with any of the models put forward to explain the breaking of self-similarity in the baryon content of clusters. In particular, the entropy profiles, scaled to the virial radius, are broadly similar in form across the sample, apart from a normalization factor that differs from simple self-similar scaling with temperature. Low-mass systems do not show the large isentropic cores predicted by preheating models, and the high entropy excesses reported at large radii in groups by Finoguenov et al. are confirmed, and found to extend even to moderately-rich clusters. We discuss the implications of these results for the evolutionary history of hot gas in clusters, and suggest that preheating may affect the entropy of intracluster gas primarily by reducing the density of material accreting into groups and clusters along cosmic filaments.

Subfields: Astronomy and Astrophysics, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/52e5cccb06b6b9db43bf4afc40fa7e6196845ea0

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Citations in the corpus

Scaling laws in X-ray galaxy clusters at redshift between 0.4 and 1.3 (2003, background): “However, these models are in conflict with recent observations of non-isentropic cores in galaxy groups (e.g. Ponman et al. 2003; Mushotzky et al. 2003).”
A unified model for AGN feedback in cosmological simulations of structure formation (2007, background): “…000–000 ature and entropy profiles into much better agreement with observational findings of cool core clusters (e.g. De Grandi & Molendi, 2002; Pratt & Arnaud, 2003; Ponman et al., 2003; Vikhlinin et al., 2005; Bauer et al., 2005; Dunn & Fabian, 2006; Sanderson et al., 2006; Pratt et al., 2007).”
LoCuSS: comparison of observed X-ray and lensing galaxy cluster scaling relations with simulations (2008, methodology): “We scaled the radial entropy profiles using the empirically scaling (Ponman et al. 2003) S ∝ T 0.65 and r500.”
The representative XMM-Newton cluster structure survey (REXCESS) of an X-ray luminosity selected galaxy cluster sample (2007, background): “…relations as a consequence of energy input from other sources, related to galaxy and star formation processes and the cooling of dense intracluster gas regions (e.g. Kaiser 1991; Bower 1997; Ponman et al. 1999, 2003; Voit & Bryan 2000; Voit et al. 2003; Pratt & Arnaud 2005; Pratt et al. 2006).”
Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction (2009, background): “…ASCAdata indicated that groups had flatter entropy profiles than cluster scale objects (David et al. 1996), and measurements of the entropy at 0.1R200 revealed an entropytemperature (K − T) relation that was shallower than expected (Ponman et al. 1999; Lloyd-Davies et al. 2000; Ponman et al. 2003).”
X‐ray properties of galaxy clusters and groups from a cosmological hydrodynamical simulation (2003, methodology): “Although this is quite expected, as long as non–gravitational effects are negligible, it conflicts with the recent results by Ponman et al. (2003).”
The XMM-Newton Wide-Field Survey in the COSMOS Field: Statistical Properties of Clusters of Galaxies (2006, background): “Understanding these scaling relations apparently requires more ingredients than simple heating by adiabatic compression during the growth of fluctuations (Kaiser 1986; Ponman et al. 2003, Borgani et al. 2004, 2005).”
The GEMS project: X-ray analysis and statistical properties of the group sample (2004, background): “Firstly, individual groups do not show isentropic cores, as would be expected in such a simple preheating model (Pratt & Arnaud 2003; Ponman et al. 2003; Sun et al. 2003; Mushotzky 2003; Rasmussen & Ponman 2004; Khosroshahi, Jones & Ponman 2004), and secondly the scaling properties of entropy in…”
Galaxy-cluster gas-density distributions of the Representative XMM-Newton Cluster Structure Survey (REXCESS) (2008, unknown): “The observed departure from simple scaling of the entropy-temperature relation for clusters (e.g. Finoguenov et al. 2002, Ponman et al. 2003) implies a temperature dependence of the gas density normalisation such thatne ∝ T 0.525.”
INTRACLUSTER MEDIUM ENTROPY PROFILES FOR A CHANDRA ARCHIVAL SAMPLE OF GALAXY CLUSTERS (2009, background): “…flattens at less than 0.1rvirial, or that the core entropy has much larger dispersion than the entropy at larger radii (David et al. 1996; Ponman et al. 1999; Lloyd-Davies et al. 2000; Ponman et al. 2003; Piffaretti et al. 2005; Donahue et al. 2005, 2006; Pratt et al. 2006; Morandi & Ettori 2007).”
Temperature profiles of a representative sample of nearby X-ray galaxy clusters (2006, background): “…in the underlying gravitational mass distribution (such as has already been seen in the X-ray mass profiles of morphologically relaxed clusters, e.g., Pointecouteau et al. 2005), and similarity in the entropy of the ICM (such as has been seen by e.g., Ponman et al. 2003; Pratt et al. 2006).”
CHANDRA STUDIES OF THE X-RAY GAS PROPERTIES OF GALAXY GROUPS (2008, methodology): “The Ponman et al. (2003) results rely on extrapolations based on assumed density (β-model) and temperature (polytropic-model) profiles, which may not be adequate and may bias the derived ICM properties (e.g., Borgani et al. 2004; Vikhlinin et al. 2006, V06 hereafter).”
Radial temperature profiles for a large sample of galaxy clusters observed with XMM-Newton (2008, background): “…can also be combined to determine the ICM entropy distribution, that provides valuable information on the cluster thermodynamic history and has proven to be a powerful tool to investigate non-gravitational processes (e.g. Ponman et al. 2003; McCarthy et al. 2004; Voit 2005; Pratt et al. 2006).”
The case for AGN feedback in galaxy groups (2009, background): “One way to examine the trends with mass and scatter is to plot the entropy at several fixed characteristic radii versus system mass, or some proxy for system mass such as the mean X-ray temperature (see, e.g., Ponman et al. 2003).”