Scaling laws in X-ray galaxy clusters at redshift between 0.4 and 1.3

By S. Ettori, P. Tozzi, Stefano Borgani, Piero Rosati. 2003

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We present a study of the integrated physical properties of a sample of 28 X-ray galaxy clusters observed with Chandra at a redshift between 0.4 and 1.3. In particular, we have twelve objects in the redshift range 0.4–0.6, five between 0.6 and 0.8, seven between 0.8 and 1 and four at $z>1.0$, compounding the largest sample available for such a study. We focus particularly on the properties and evolution of the X-ray scaling laws. We fit both a single and a double $\beta-$model with the former which provides a good representation of the observed surface brightness profiles, indicating that these clusters do not show any significant excess in their central brightness. By using the best-fit parameters of the $\beta-$model together with the measured emission-weighted temperature (in the range 3–11 keV), we recover gas luminosity, gas mass and total gravitating mass out to R 500 . We observe scaling relations steeper than expected from the self-similar model by a significant (>$3 \sigma$) amount in the $L-T$ and $M_{\rm gas}-T$ relations and by a marginal value in the $M_{\rm tot}-T$ and $L-M_{\rm tot}$ relations. The degree of evolution of the $M_{\rm tot}-T$ relation is found to be consistent with the expectation based on the hydrostatic equilibrium for gas within virialized dark matter halos. We detect hints of negative evolution in the $L-T$, $M_{\rm gas}-T$ and $L-M_{\rm tot}$ relations, thus suggesting that systems at higher redshift have lower X-ray luminosity and gas mass for fixed temperature. In particular, when the 16 clusters at $z>0.6$ are considered, the evolution becomes more evident and its power-law modelization is a statistically good description of the data. In this subsample, we also find significant evidence for positive evolution, such as $(1\,+\,z)^{0.3}$, in the $E_z^{4/3} S - T$ relation, where the entropy S is defined as $T/n_{\rm gas}^{2/3}$ and is measured at 0.1$\,R_{200}$. Such results point toward a scenario in which a relatively lower gas density is present in high-redshift objects, thus implying a suppressed X-ray emission, a smaller amount of gas mass and a higher entropy level. This represents a non-trivial constraint for models aiming at explaining the thermal history of the intra-cluster medium out to the highest redshift reached so far.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/fa5966109ce5913f1741107c21cf9d9147c02b0f

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Citations in the corpus

The representative XMM-Newton cluster structure survey (REXCESS) of an X-ray luminosity selected galaxy cluster sample (2007, background): “For even larger redshifts a systematic study of the RDCS clusters from Rosati et al. (1998, 2002, e.g. Ettori et al. 2004) and of the 160 deg2 of Vikhlinin et al. (1998) is ongoing (e.g. Kotov & Vikhlinin 2006).”
Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction (2009, background): “In addition, indications for excess ntropy have been found at large radius in intermediate redshift groups (Jeltema et al. 2006), and the first measurements of the entropy evolution have been undertaken (Ettori et al. 2004).”
The Observed Growth of Massive Galaxy Clusters II: X-ray Scaling Relations (2009, result): “Ettori et al. (2004) and Morandi et al. (2007) went further, by adopting a model for evolution as in equation (6) with ζ = 1 + z.”
The X-Ray Luminosity-Mass Relation for Local Clusters of Galaxies (2006, background): “However, Ettori et al. (2004) do not see strong evolution to z=1.3 in the luminosity–mass relation with a sample of 28 clusters.”
Predictions for high-frequency radio surveys of extragalactic sources (2004, background): “(9) (see, e.g., Ettori et al. 2004 and references therein).”
X-Ray and Sunyaev-Zel’dovich Effect Measurements of the Gas Mass Fraction in Galaxy Clusters (2006, methodology): “Values of β in our sample are almost entirely in the range 0.5 to 1.0, with most clustered between 0.6 and 0.8; this range is also consistent with many independent studies using other cluster samples (e.g., Jones & Forman 1999; Mohr et al. 1999; Ettori et al. 2004).”
The XMM-Newton Wide-Field Survey in the COSMOS Field: Statistical Properties of Clusters of Galaxies (2006, methodology): “…Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748, Garching, Germany objects, observable quantities like X-ray luminosity LX and temperature TX show fairly tight relations with the cluster mass (e.g. Evrard et al. 1996, Allen et al. 2001, Reiprich & Böhringer 2002, Ettori et al. 2004).”