What is a cool-core cluster? a detailed analysis of the cores of the X-ray flux-limited HIFLUGCS cluster sample

D. S. Hudson; R. Mittal; T. H. Reiprich; P. E. J. Nulsen; H. Andernach; C. L. Sarazin

doi:10.1051/0004-6361/200912377

Free Access

Issue		A&A Volume 513, April 2010


Article Number		A37
Number of page(s)		40
Section		Cosmology (including clusters of galaxies)
DOI		https://doi.org/10.1051/0004-6361/200912377
Published online		21 April 2010

Online Material

Appendix A: Calculating central density for a double $\beta$ model

Starting from the definition of the normalization of the APEC model (Mewe et al. 1985; Smith et al. 2001; Mewe et al. 1986; Smith & Brickhouse 2000) and taking $n(r) = n_{\rm e}$ with $\zeta = \frac{n_{\rm e}}{n_{\rm H}}$ , (calculated individually, but generally $\sim$ 1.2),

$\begin{displaymath} {\mathcal N} \equiv \frac{10^{-14}}{4\pi\:D_{\rm A}\:D_{\rm L}\:\zeta}\int n(r)^2 {\rm d}V, \end{displaymath}$

(A.1)

where the terms are defined as in Eq. (9). For a double $\beta$ model the expression for n(r) is:

$\begin{displaymath}n(r) = \left[ n_{01}^{2} \left( 1 + \left( \frac{r}{r_{\rm c_... ...} \right)^{2} \right)^{-3\beta_{2}} \right]^{\frac{1}{2}}\cdot \end{displaymath}$

(A.2)

The unabsorbed surface brightness at a projected distance, x from the center over an energy range between E₁ and E₂ is

$\begin{displaymath} \Sigma(x) = \frac{\int_{E_{1}}^{E_{2}} \Lambda_{\rm X}(T,Z,E... ...4\pi (1+z)^{4}\:\zeta}\int_{-\infty}^{\infty} n(r)^2 {\rm d}l, \end{displaymath}$

(A.3)

where r² = x² + l² and $\Lambda_{\rm X}(T,Z,E)$ is the emissivity function for a plasma of temperature T and metalicity Zat energy E. This can be rewritten in terms of n₀₁ and n₀₂ as:

$\begin{displaymath}\Sigma(x) = \frac{\int_{E_{1}}^{E_{2}}\Lambda_{\rm X}(T,Z,E){... ...^2}{x_{\rm c_{2}}^{2}} \right) \right)^{-3\beta_{2}} {\rm d}l. \end{displaymath}$

(A.4)

Solving the integral gives the standard expression for the double $\beta$ model in terms of surface brightness:

$\begin{displaymath}\Sigma(x) = \Sigma_{01} \left( 1 + \left( \frac{x}{x_{\rm c_{... ..._{\rm c_{2}}} \right)^{2} \right)^{-3\beta_{2} + \frac{1}{2}}, \end{displaymath}$

(A.5)

where

$\begin{displaymath}\Sigma_{0i} \equiv \frac{n_{0i}^2 \int_{E_{1}}^{E_{2}} \Lambd... ...} \right)} \int_{E_{1}}^{E_{2}}\Lambda_{\rm X}(T,Z,E){\rm d}E. \end{displaymath}$

(A.6)

Therefore,

$\begin{displaymath}\frac{n_{01}^2}{n_{02}^2} = \frac{\Sigma_{01} {\rm LI}_{2}}{\... ...\rm LI}_{1}} = \frac{\Sigma_{12}\:{\rm LI}_{2}}{{\rm LI}_{1}}, \end{displaymath}$

(A.7)

where LI_i and $\Sigma_{12}$ are as defined in Eq. (12). Using this relation along with the fact that $n_{0} \equiv n(0) = \sqrt{n_{01}^2 + n_{02}^2}$ , we find:

$\begin{displaymath}n_{01}^2 = \frac{\Sigma_{12}\:{\rm LI}_{2}}{\Sigma_{12}\:{\rm LI}_{2}+{\rm LI}_{1}} n_{0}^2, \end{displaymath}$

(A.8)

and

$\begin{displaymath}n_{02}^2 = \frac{{\rm LI}_{1}}{\Sigma_{12}\:{\rm LI}_{2}+{\rm LI}_{1}} n_{0}^2\cdot \end{displaymath}$

(A.9)

Inserting these values into Eq. (A.2) to find an expression for n(r) in terms of n₀, we get

$\begin{displaymath}n(r) =\frac{n_{0}}{\sqrt{\Sigma_{12}\:{\rm LI}_{2}+ {\rm LI}_... ...{2}}} \right)^{2} \right)^{-3\beta_{2}} \right]^{\frac{1}{2}}. \end{displaymath}$

(A.10)

Inserting this expression of n(r) into Eq. (A.1) and solving for n₀, we recover Eq. (12).

Appendix B: K $_{\rm BIAS}$ calculations

From the definition of surface brightness (Eq. (A.3)), a cluster at redshift z, of a region with an angular radius x, has an integrated surface brightness (or Flux ${\mathcal F}$ ) between energies E₁ and E₂:

$\begin{displaymath} {\mathcal F} = \frac{\int_{E_{1}}^{E_{2}} \Lambda_{\rm X}(T... ...\infty} \int_{0}^{x} n_{\rm e} n_{\rm H}\;x {\rm d}x {\rm d}l, \end{displaymath}$

(B.1)

where $n_{\rm e}$ is the electron density, $n_{\rm H}$ is the proton density, $\Lambda_{\rm X}(T,Z,E)$ is the emissivity function as defined in Eq. (A.3). To remove the redshift dependence of the projected region size, we convert the projected region of angular radius x to a cylindrical region of physical radius R, such that $R \approx xD_{\rm A}(z)$ . Equation (B.1) becomes:

$\begin{displaymath} {\mathcal F} = \frac{\int_{E_{1}}^{E_{2}} \Lambda_{\rm X}(T,Z,E){\rm d}E}{4\pi\:D_{\rm A}\:D_{\rm L}\:(1+z)^2} I(R), \end{displaymath}$

(B.2)

where $D_{\rm A}$ is angular diameter distance, $D_{\rm L}$ is the luminosity distance and I(R) is defined as in Eq. (20). Therefore the total counts ${\mathcal C}$ collected by a telescope for an observation of length $t_{\rm obs}$ , in an energy band from E₁ to E₂, of a cylindrical region of physical radius R is:

$\begin{displaymath} {\mathcal C} = t_{\rm obs} \frac{\int_{E_{1}}^{E_{2}} \alph... ...\rm eff}(E) {\rm d}E}{4\pi D_{\rm A} D_{\rm L}\;(1+z)^2} I(R), \end{displaymath}$

(B.3)

where $\alpha(E)$ and $A_{\rm eff}(E)$ are the absorption from Galactic hydrogen and the effective area of the telescope at energy E, respectively. We can calculate $\int_{E_{1}}^{E_{2}}\alpha(E)\Lambda_{\rm X}(T,Z,E)A_{\rm eff}(E){\rm d}E$ for an absorbed thermal model using XSPEC with an appropriate ARF and RMF. Specifically, since normalization ${\mathcal N} \propto {\mathcal CR} \equiv C/t_{\rm obs}$ , XSPEC can be used to find the constant of proportionality $\kappa$ . From the definition of ${\mathcal N}$ (see Eq. (A.1)):

$\begin{displaymath}\int_{E_{1}}^{E_{2}}\alpha(E)\Lambda_{\rm X}(T,Z,E)A_{\rm eff}(E){\rm d}E= \frac{(1+z)^2\kappa}{10^{14}}, \end{displaymath}$

(B.4)

so that

$\begin{displaymath} {\mathcal C} = t_{\rm obs} \frac{10^{-14}\;\kappa}{4\pi D_{\rm A} D_{\rm L}} I(R). \end{displaymath}$

(B.5)

Using an on-axis Chandra ARF and RMF, we determined $\kappa$ (122.3 photons cm⁵ s^-1) for an energy band from 0.5-7.0 keV, with Z = 0.25 solar, $N_{\rm H} = 2 \times 10^{20}$ cm^-2and our median observation time (44 ks), redshift (0.047) and virial temperature (4.3 keV). Inserting our determined value of $\kappa$ into Eq. (B.5) and solving for I, such that C = 10 000 counts, yields $I = 8.6 \times 10^{65}$ h₇₁^-2 cm^-3. Therefore using the criterion that our median observation would have $K_{\rm BIAS}$ determined by circle with 10 000 counts, equivalent regions from other observations would have:

$\begin{displaymath}\frac{{\mathcal C}}{{\rm cnts}} = 17~910 \left ( \frac{ t_{\r... ...{200 \;h_{71}^{-1}\;{\rm Mpc}}{D_{\rm A}(1+z)} \right )^2\cdot \end{displaymath}$

(B.6)

Appendix C: Notes on individual clusters

C.1 A0085

This cluster appears to have two subclumps, one near the center and one further to the south (Kempner et al. 2002). In determining the temperature profile and global cluster temperature the latter was excluded. This SCC cluster hosts a well-studied radio relic, which is close to but not connected to the central radio galaxy (e.g. Slee et al. 2001). The central region of this cluster requires a double thermal model out to $\sim$ 11 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 12 h₇₁^-1 kpc).

C.2 A0119

This is possibly a merging cluster, which shows elongation towards the northeast. The X-ray peak of this NCC cluster, which does not dominate the surface brightness, has a cD galaxy cospatial with it. The cluster contains three wide-angle-tailed (WAT) radio galaxies which may be interacting with the ICM (e.g. Feretti et al. 1999).

C.3 A0133

Central regions of this cluster show an east-west elongation. An in-depth study with XMM and Chandra by Fujita et al. (2004,2002) revealed an X-ray tongue extending northwest. This SCC cluster hosts a radio relic, that is close to but not connected to the central radio galaxy (e.g. Slee et al. 2001). The central region of this cluster requires a double thermal model out to $\sim$ 15 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 16 h₇₁^-1 kpc).

C.4 NGC 0507 group

The overall X-ray spectrum of this group shows a suspicious hard tail. An additional powerlaw component was included in the overall temperature fit. It is possible that the hard tail is due to unresolved low mass X-ray binaries (LMXBs), although the central region ( $\sim$ $1\hbox{$.\mkern-4mu^\prime$ }8 = 35.7~h_{71}^{-1}$ kpc) was removed and no evidence of a hard excess is seen in the spectra of the central annuli. It is possible that (given the redshift of NGC 0507 z = 0.0165) the LMXBs are only strong enough to be measured in a large region and are insignificant compared to the group emission in the central region. On the other hand the powerlaw has a steep photon index ( $\Gamma_{\rm X} = 2.3{-}3.0$ ) that is not consistent with LMXBs, which usually have a photon index of $\Gamma_{\rm X}=1.6$ . The component has a total flux of $\sim$ $4 \times 10^{-12}$ erg cm^-2 s^-1corresponding to a luminosity of $2 \times 10^{42}$ h₇₁^-2 erg s^-1 (over 0.4-10.0 keV). It is also possible that the hard excess is related to an insufficiently subtracted particle background, which is visible in this cool cluster. Both models (additional particle background or powerlaw) give an identical overall temperature. We also note that a more detailed analysis of the residual background in outer cluster regions shows no residual particle background. The central region of this cluster requires a double thermal model out to $\sim$ 62 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 20.6 h₇₁^-1 kpc).

C.5 A0262

The spectral fits to the inner regions are poor ( $\chi^2$ /d.o.f. $\sim$ 1.4) even with a double thermal model. Using non-solar abundance ratios significantly improves the fit, but does not change the best-fit overall temperature. We therefore used solar ratios for simplicity. The central region of this cluster requires a double thermal model out to $\sim$ 43 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 14 h₇₁^-1 kpc).

C.6 A0400

This cluster hosts the double radio source 3C75 within its center and shows evidence of merging (Hudson et al. 2006). As noted in Hudson et al. (2006), the hydrogen column density is higher than measured in the radio ( $N_{\rm H} = 0.85 \times 10^{21}$ cm^-2 Kalberla et al. 2005) and therefore we left it free for all spectral fits. We find a hydrogen column density of $N_{\rm H} = 0.98{-}1.22 \times 10^{21}$ cm^-2 for our fit to the overall cluster.

C.7 A0399

This cluster is near to A401 and shows evidence of interaction with A401 (e.g. Sakelliou & Ponman 2004). The temperature profile of this cluster peaks at the X-ray center.

C.8 A0401

See also A0399. This cluster may host a radio halo (Giovannini et al. 1999). We included an early observation (before 2001), since the later observation was offset, with the cluster center in the corner of a CCD. The BCG closest to the X-ray peak is $\sim$ 34 h₇₁^-1 kpc away, making it one of fourteen clusters with the BCG >12 h₇₁^-1 kpc from the X-ray peak.

C.9 A3112

Although the background flaring seen in some observations was removed, the effect seems to have broadened a fluorescence line. This can be seen in the fit to the overall cluster spectrum (at $\sim$ 7.5 keV). This effect seems simply to make the fit poor ( $\chi^2$ /d.o.f. $\sim$ 1.6), but it does not affect the best-fit values whether the line is removed or not. Takizawa et al. (2003) first presented the Chandra data of A3112, interpreting the radio active central cD galaxy as interacting with the ICM. Bonamente et al. (2007) claim a soft excess and hard excess in this cluster that may be related with the central radio active BCG. We do not see a similar effect, however we do not separately fit the 1 $\hbox{$^\prime$ }$ -2 $\hbox{$.\mkern-4mu^\prime$ }$ 5 annulus that Bonamente et al. (2007) fit. We do confirm that the 1 $\hbox{$^\prime$ }$ -2 $\hbox{$.\mkern-4mu^\prime$ }$ 5 annulus is isothermal in our kT-profile so that their result is not due to a temperature fluctuations in the cluster. This SCC cluster is one of sixteen clusters for which no data exist for the BCG central velocity dispersion.

C.10 NGC 1399/Fornax cluster

This nearby SCC cluster has two X-ray peaks cospatial with NGC 1399 and NGC 1404. The X-ray peak is taken to be cospatial with the BCG NGC 1399. The peak on NGC 1404 was removed for spatial and spectral analysis. Fornax appears to be an outlier in six of the plots of parameters versus CCT in which it has an anomalously low value for its CCT. These parameters are: (1) ${\Sigma _{0}}$ ; (2) ${r}_{\rm c}$ /r₅₀₀; (3) $K_{\rm BIAS}$ ; (4) cooling radius; (5) $\dot{M}_{\rm classical}$ /M₅₀₀ and (6) ${M}_{\rm gas}$ /M₅₀₀. Additionally it is the only SCC cluster in which $\dot{M}_{\rm classical} \leq \dot{M}_{\rm spec}$ . One possible explanation is that NGC 1404 is about 0.04 r₅₀₀ from the X-ray peak and due to the extended emission around it, the surface brightness profile severely flattens. The extrapolated outer profile therefore overestimates the projected gas lowering the central density (and altering associated parameters). To check how much this influenced the Fornax cluster as an outlier, we fit only the central part of the surface brightness that could be fit well to a single $\beta$ -model. This model most likely underestimates the projected gas, thereby providing the largest possible values for central density. In the case of Fig. 10, this model raises $\dot{M}_{\rm classical}$ to $0.75 \pm 0.04~h_{71}^{-2}$ $M_{\odot }$ yr^-1making it larger than $\dot{M}_{\rm spectral} = 0.52\pm0.02~M_{\odot}$ yr^-1. We emphasize that this result overestimates $\dot{M}_{\rm classical}$ and in any case $\dot{M}_{\rm spec}$ $\approx$ $\dot{M}_{\rm classical}$ , making it an odd SCC cluster. In all other cases the Fornax cluster remains an outlier. In the case of the CCT the value falls to $\sim$ 0.4 h₇₁^-1/2 Gyr moving the Fornax cluster to the left in Fig. 6. (1) ${\Sigma _{0}}$ , not surprisingly, remains almost the same, $\sim$ $0.21 \times 10^{-6}$ photons cm^-2 s^-1 arcsec^-2. The shift to the left in this case makes the Fornax cluster even more of an outlier. (2) $r_{\rm c}/r_{500}$ , likewise, remains almost identical, $\sim$ $4 \times 10^{-4}$ . Unlike, ${\Sigma _{0}}$ , the shift to the left in this case makes the Fornax cluster more similar to other SCC clusters. (3) $K_{\rm BIAS}$ is, of course, unaffected by the density model, however moving the Fornax cluster to the left makes it more consistent with the other SCC clusters. (4) The cooling radius remains almost identical, increasing to 0.03 r₅₀₀. Additionally moving the Fornax cluster to the left makes it even more of an outlier. (5) $\dot{M}_{\rm classical}$ /M₅₀₀ increases slightly to $\sim$ $1.8 \times 10^{-14}$ h₇₁^-1 yr^-1. Moving the Fornax cluster to the left makes the trend of decreasing $\dot{M}_{\rm classical}$ /M₅₀₀ with CCT worse, but it is more consistent with other groups with short CCT. (6) ${M}_{\rm gas}$ /M₅₀₀, is raised slightly, $\sim$ $0.2 \times 10^{-3}$ . Similar to $\dot{M}_{\rm classical}$ /M₅₀₀, moving the Fornax cluster to the left makes the trend with CCT worse, but makes it more consistent with the other groups. We emphasize that the Fornax cluster is still an outlier in all six cases, and that these values are the other extrema, with the true value somewhere between these and where they are plotted in Fig. 6. The physical interpretation is that it is possible that Fornax is in the process of forming a cool core (i.e. it has a nascent core in the terms of Burns et al. (2008)) and therefore is dynamically different from the other SCC clusters that have well-established cores. The central region of this cluster requires a double thermal model out to $\sim$ 170 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 15.9 h₇₁^-1 kpc).

C.11 2A0335+096

This cluster, along with A0478 and NGC 1550, has a significantly higher hydrogen column density than measured at radio wavelengths ( $N_{\rm H} = 1.68 \times 10^{21}$ cm^-2 Kalberla et al. 2005). We fit all spectra with the column density free. For the fit to the overall spectrum we find $N_{\rm H} = 2.35{-}2.47 \times 10^{21}$ cm^-2. This cluster has two major galaxies near the X-ray peak, which resides between the two of them ( $\sim$ 10 h₇₁^-1 kpc from the closest). Of the 16 clusters in which no information about the BCG central velocity dispersion is available, this cluster has the shortest CCT. The central region of this cluster requires a double thermal model out to $\sim$ 38 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 26 h₇₁^-1 kpc).

C.12 IIIZw54

IIIZw54 is a pair of galaxies near the center of a poor galaxy group. We used a 6 $\hbox {$^{\prime \prime }$ }$ kernel when smoothing the image in order to determine the emission peak. This cluster does not have a bright core, although it appears to be quite round and relaxed. The brighter of two galaxies in the galaxy pair IIIZw54 (a cD galaxy) is cospatial with the X-ray peak.

C.13 A3158

okas et al. (2006) report A3158 as a relaxed cluster based on the velocity dispersion of the galaxies. The X-ray emission appears to be elliptical and there are two cDs near the cluster center, one of which lies at the X-ray peak. This cluster definitely does not have a bright core, with a central density of only $\sim$ $5 \times 10^{-3}$ cm^-3. The temperature profile peaks in the center at $\sim$ 5.7 keV.

C.14 A0478

This cluster, along with 2A0335+096 and NGC 1550, has a significantly higher hydrogen column density than measured in the radio ( $N_{\rm H} = 1.64 \times 10^{21}$ cm^-2 Kalberla et al. 2005). We fit all spectra with the column density free. Our fit to the overall cluster yields a column density of ( $N_{\rm H} = 2.89{-}2.96 \times 10^{21}$ cm^-2), consistent with the value found by Sanderson et al. (2005). This cluster has the highest spectral mass deposition rate of any HIFLUGCS cluster, making it an ideal candidate for a grating observation. Unfortunately the RGS data from a long XMM-Newton exposure was virtually unusable (de Plaa et al. 2004). This SCC cluster is also one of sixteen clusters in which no data for the BCG central velocity dispersion are available.

C.15 NGC 1550 group

This cluster, along with 2A0335+096 and A0478, has a significantly higher hydrogen column density than measured in the radio ( $N_{\rm H} = 0.981 \times 10^{21}$ cm^-2 Kalberla et al. 2005). We fit all spectra with the column density free. Our fit to the overall cluster yields a column density of $N_{\rm H} = 1.34{-}1.41 \times 10^{21}$ cm^-2. The column density appears to peak towards the center of the cluster, having a value of $N_{\rm H} = 1.9{-}2.2 \times 10^{21}$ cm^-2 in the innermost annulus.

C.16 EXO0422-086/RBS 0540

The short observation of this SCC cluster indicates a round, centrally peaked cluster with a moderate central temperature drop. The BL Lac object EXO 0423.4-0840 at the center of this cluster was studied by Belsole et al. (2005). This is one of sixteen clusters for which no data about the BCG central velocity dispersion are available.

C.17 A3266

This cluster has a very low background scaling factor; therefore an additional unfolded powerlaw component was included in the spectral fits to account for any residual particle background. Reading in the background as a corfile (i.e. a second background component with an adjustable scaling factor), the overall best-fit temperature is found to be consistent with our result including an unfolded powerlaw. Henriksen & Tittley (2002); Finoguenov et al. (2006) presented detailed analyses of this merging system.

C.18 A0496

The high abundances in the central region of this cluster are better fit with a VAPEC model, however since this did not change the best-fit values of temperature, solar ratios were used for simplicity. A double thermal model greatly improved the fits to spectra in annuli out to 0 $\hbox{$.\mkern-4mu^\prime$ }$ 3. However, the high temperature component for annuli between 0 $\hbox{$.\mkern-4mu^\prime$ }$ 18 and 0 $\hbox{$.\mkern-4mu^\prime$ }$ 3 is $\gg$ $kT_{\rm vir}$ ( $kT \sim 8$ keV). Although this may be evidence of very hot gas near the cluster core, the investigation is beyond the scope of this paper. Therefore for annuli between 0 $\hbox{$.\mkern-4mu^\prime$ }$ 18 and 0 $\hbox{$.\mkern-4mu^\prime$ }$ 3, we used a single thermal fit. Dupke et al. (2007a) studied the longest of the three Chandra observations of this cluster in depth. They argue that there is a cold front at the center of this cluster, which is caused by an off-center passage of a smaller dark matter halo.

C.19 A3376

This cluster was fit with an unfolded powerlaw component to account for possible low-level flares in both observations. This cluster appears highly disturbed in the X-ray with a strong elongation along the east-west direction. Bagchi et al. (2006) report the existence of double relics, one to the east of the cluster center and one to the west. Nevalainen et al. (2004) found a diffuse, hard excess with the BeppoSAX PDS at 2.7 $\sigma$ significance. The BCG of this cluster is $\sim$ 1 Mpc from the X-ray peak, the most distant of any cluster in the sample and one of eight clusters with a separation of >50 h₇₁^-1 kpc. There is a radio galaxy with bent jets very close to the X-ray peak (Mittal et al. 2009). Optically it is clearly much fainter than the BCG and is most likely an AGN that may have been activated by the merger. The jets are bent in the opposite direction to the elongation of the cluster, possibly bent from ICM ram pressure.

C.20 A3391

The short observation of this NCC cluster shows an elliptical shaped ICM with a BCG cospatial with the emission peak. Tittley & Henriksen (2001) discovered a filament between A3391 and the nearby cluster A3395.

C.21 A3395s

This cluster is very close to and may be interacting with A3395e. A3395e was excluded from all extended analysis. Donnelly et al. (2001) claim A3395s and A3395e are near first core passage.

C.22 A0576

Kempner & David (2004) originally presented an analysis of the Chandra data. Dupke et al. (2007b) presented a detailed analysis of the XMM-Newton and Chandra data suggesting that it is a line-of-sight merger. The X-ray image seems somewhat perturbed with elliptical isophotes with alternating NW-SE shifted centers, reminiscent of sloshing, already noted by Kempner & David (2004). The BCG is $\sim$ 24 h₇₁^-1 kpc from the X-ray peak, making it one of fourteen clusters with the separation >12 h₇₁^-1 kpc. There is, however, a slightly fainter galaxy closer (<12 h₇₁^-1 kpc) to the X-ray peak that is radio active, whereas the BCG is not. The peculiar velocity of the BCG is one of five clusters that is more than 50% of the velocity dispersion. This WCC cluster is one of the three WCC/NCC clusters with CCT $\gg$ 1 h₇₁^-1/2 Gyr (i.e. not on the border between SCC and WCC) and a systematic temperature decrease at the cluster center.

C.23 A0754

This irregularly shaped cluster hosts a halo and relic (Kassim et al. 2001). Henry et al. (2004) presented a detailed analysis of this merging system using the XMM-Newton observation. Only the pre-2001 Chandra observation is used, since it was the only one that contained the cluster core. More recent observation have been made but do not cover the cluster center and therefore are not useful for core studies. The BCG for this cluster is $\sim$ 714 h₇₁^-1 kpc away from the X-ray peak, making it one of eight clusters where this separation is >50 h₇₁^-1 kpc.

C.24 A0780/Hydra-A cluster

This cluster is known to have a massive central AGN outburst (Nulsen et al. 2005).

C.25 A1060

This WCC cluster is also known as the Hydra cluster. Sato et al. (2007) recently presented a Suzaku observation of this cluster. This cluster has two bright galaxies near the core, one of which is cospatial with X-ray peak. Both galaxies have a clearly visible diffuse X-ray component (Yamasaki et al. 2002).

C.26 A1367

Due to the short exposure time and lack of a bright core, we used a 12 $\hbox {$^{\prime \prime }$ }$ kernel when smoothing to determine the X-ray peak. This is a very well-studied merging cluster. This cluster has an infalling starburst group (Cortese et al. 2006; Sun et al. 2005) and optical evidence suggests that this is a merging system (Cortese et al. 2004). The X-ray image appears rather disturbed with several off-centered bright sources. Sun & Vikhlinin (2005) studied the survival of galaxy coronae in this system. This cluster hosts a radio relic (Gavazzi & Trinchieri 1983). The BCG of this cluster is $\sim$ 666 h₇₁^-1 kpc from the X-ray peak making it one of eight clusters where this separation is >50 h₇₁^-1 kpc. It is also one of five clusters where the BCG peculiar velocity is >50% of the cluster velocity dispersion.

C.27 MKW4

A single thermal model is a poor fit to this high metalicity center. Although a second thermal model does provide an improvement, freeing the ratio of elements for a single thermal model provides the best-fit. Since freeing the abundance ratios does not change the overall best-fit temperatures of the annuli, solar ratios with a single thermal model were used for simplicity.

C.28 ZwCl 1215.1+0400

The short observation of this NCC cluster, shows a round cluster with no bright central peak and an elliptical BCG located at the X-ray emission peak. This is one of the sixteen clusters for which no data about the BCG central velocity dispersion are available. The BCG of this clusters is also $\sim$ 18 h₇₁^-1 kpc from the X-ray peak, making it one of fourteen clusters where this separation is >12 h₇₁^-1 kpc.

C.29 NGC 4636 group

This nearby group contains extended nonthermal emission in the central region extending out $\sim$ 122 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 9.19 h₇₁^-1 kpc). The luminosity of this emission ( $L_{\rm X} \sim 10^{40}$ h₇₁^-2 erg s^-1) is consistent with the expected unresolved LMXB population for NGC 4636. In addition to a powerlaw component, the central region of this cluster requires a double thermal model out to $\sim$ 35 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 2.6 h₇₁^-1 kpc).

C.30 A3526/Centaurus cluster

This is a well-studied, prototypical CC cluster, with a central temperature drop (having the largest fractional drop, $kT_{0} \sim 0.2 kT_{\rm vir}$ ) and enhanced central metalicity. An arc-like X-ray feature near the center has been identified as most likely being a cold front associated with sloshing in the core (Sanders & Fabian 2002). The central region of this cluster requires a double thermal model out to $\sim$ 72 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 16.5 h₇₁^-1 kpc).

C.31 A1644

As with A0085, this SCC cluster shows evidence of merging, with the existence of a double X-ray peak. Reiprich et al. (2004) analyzed the XMM EPIC observation of this cluster. They found the flux of the northern (smaller) subclump is below the HIFLUGCS flux limit whereas the flux of the southern (larger) subclump is above the flux limit. Therefore for purposes of this analysis the smaller subclump was excluded from spatial and spectral analysis. Additionally Reiprich et al. (2004) found evidence that the smaller sub-clump was being stripped as it passes through the ICM. This is one of sixteen clusters in which the central velocity dispersion of the BCG is unavailable. The central region of this cluster requires a double thermal model out to $\sim$ 32 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 30 h₇₁^-1 kpc).

C.32 A1650

This CC cluster hosts a radio quiet cD galaxy (Donahue et al. 2005). Mittal et al. (2009) find an upper-limit to the bolometric radio luminosity of $\sim$ $9 \times 10^{38}$ h₇₁^-2 erg s^-1. The original short Chandra observation showed a flat temperature profile (Donahue et al. 2005). However, the longer, mosaiced observations show a slight temperature decrease in the central region. Due to the elevated entropy in the core, Donahue et al. (2005) concluded a major AGN outburst had disrupted the cooling flow. This cluster is one of four clusters on the border between SCC and WCC. Its CCT ( $\sim$ 1.2 h₇₁^-1/2 Gyr) is slightly longer than the 1 Gyr cutoff. Moreover this cluster shows a central temperature decrease typical of SCC clusters. This is one of sixteen clusters in which the central velocity dispersion of the BCG is unavailable.

C.33 A1651

As with A1650, Donahue et al. (2005) claim this is a radio quiet CC cluster, however Mittal et al. (2009) detect central radio emission with a bolometric luminosity of $\sim$ 10⁴⁰ h₇₁^-2 erg s^-1. Gonzalez et al. (2000) fit the optical light out to $\sim$ 670 h₁₀₀^-1 kpc, over one quarter of ${r}_{\rm vir}$ . The X-ray structure looks quite round and shows no evidence of external interaction. However, the X-ray peak does not dominate as much as in SCC clusters and there is no evidence of a central temperature drop. This WCC is one of sixteen clusters in which the central velocity dispersion of the BCG is unavailable.

C.34 A1656/Coma cluster

This well-studied NCC cluster appears to be involved in a merger with a group. This cluster hosts the first detected radio halo (Willson 1970).

C.35 NGC 5044 troup

The spectra for the inner regions of this group are not well fit by a single thermal model ( $\chi^2$ /d.o.f. > 2). After trying several different models to fit the residuals, we found that the statically best model which is also physically motivated is a thermal model that allows oxygen, silicon, sulfur, and iron to vary from solar ratios and a powerlaw to account for a the clear hard tail (most likely due to LMXBs). We note that a double thermal model with the above elements not constrained at solar ratios provides the statistically best-fit (in the innermost annulus $\chi^2$ /d.o.f. = 1.04 vs. $\chi^2$ /d.o.f. = 1.13 for the thermal plus powerlaw model). In this model, however, the hotter thermal model has a temperature of kT = 1.4-3.0 which is hotter than any gas found in the outer annuli and the measured virial temperature ( $kT_{\rm vir} = 1.22^{+0.03}_{-0.04}$ ). Unless there is a hot halo of gas extending from the center of the group out to $\sim$ 16 h₇₁^-1 kpc, this model is unphysical. Finally, we note that adding a powerlaw to the second thermal model does not improve the fit and similar high temperatures are found for the hotter thermal component as for the simple two thermal model.

C.36 A1736

This NCC cluster is a member of the Shapley Supercluster. Due to the short exposure time and lack of a bright core, the X-ray peak was found by smoothing the image with a $\sim$ 10 $\hbox {$^{\prime \prime }$ }$ kernel. The X-ray morphology shows an irregular shape with no well-defined core. A preliminary temperature map shows heating to the east and west of the emission peak with cool gas extending to the south. The BCG of this cluster is $\sim$ 642 h₇₁^-1 kpc from the peak, making it one of eight clusters where this separation is >50 h₇₁^-1kpc. This is the only cluster with a separation of >50 h₇₁^-1 kpc that does not have any known associated radio halo or relic.

C.37 A3558

This WCC cluster is located in the core of the Shapley Supercluster. The observation was heavily flared, and even after a conservative cleaning of the light curve there was evidence of some low-level flaring in the back-illuminated chips. Rossetti et al. (2007) presented the XMM and Chandra analysis of this cluster, concluding that it had a cool core that had survived a merger. We find evidence of a slight temperature drop in the core of this WCC cluster.

C.38 A3562

This WCC cluster is located in the core of the Shapley Supercluster. The X-ray emission from this cluster appears to be elongated along the northeast-southwest direction. Giacintucci et al. (2005) report the detection of a radio halo (also see Venturi et al. 2000) and argue for a merger scenario between A3562 and SC 1329-313. Finoguenov et al. (2004) presented a detailed analysis of the XMM observation of this cluster. The BCG of this cluster is $\sim$ 31 h₇₁^-1 kpc from the X-ray peak, making it one of fourteen clusters where this separation is >12 h₇₁^-1 kpc. However, the BCG is located in a chip gap, so the separation may simply be an instrumental effect (i.e. the peak on the BCG may not be detected due to the chip gap). The XMM observation also shows an offset between the X-ray peak and BCG but on a scale of only $\sim$ 23 h₇₁^-1 kpc (Zhang, private communication).

C.39 A3571

This WCC cluster is a member of the Shapley Supercluster.

C.40 A1795

The core of this well-studied SCC cluster has a large filament seen in X-rays and H $\alpha$ (Crawford et al. 2005). Early core studies with Chandra were done by Fabian et al. (2001) and Markevitch et al. (2001). Fabian et al. (2001) found a CCT of $\sim$ 0.4 h₇₁^-1/2 Gyr, approximately the same age as they estimate for the filament. The difference between their measurement for CCT and our measurement is probably due to the different values of $r_{\rm cool}$ used to determine CCT. In order to keep consistency between clusters we determined the CCT at 0.004 r₅₀₀, however at the redshift of A1795 we are able to determine the CCT at an even smaller radius which gives a CCT $\sim$ 0.5 h₇₁^-1/2 Gyr, consistent with Fabian et al. (2001). Moreover, their technique for determining CCT is slightly different from ours. Markevitch et al. (2001) found a cold front in the core of A1795, which they attribute to sloshing gas. Oegerle et al. (2001) studied FUSE observations and found an upper limit for $\dot{M}_{\rm spec}$ (20 kpc $) < 28~h_{71}^{-1/2}~M_{\odot}$ yr^-1, consistent with our measurement of $\sim$ 15 $M_{\odot }$ yr^-1.

C.41 A3581

This SCC cluster is a member of the Hydra-Centaurus Supercluster. The central region of this cluster requires a double thermal model out to $\sim$ 40 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 18 h₇₁^-1 kpc). Johnstone et al. (2005) analyzed the Chandra data from A3581. They find a point source coincident with the powerful radio source PKS 1404-267 at the cluster center. They find a central temperature drop to $\sim$ 0.4 $kT_{\rm vir}$ at the cluster center, similar to our measurement of $\sim$ 0.5 $kT_{\rm vir}$ .

C.42 MKW8

This NCC cluster shows little substructure in the X-ray image. The X-ray isophotes are elliptical with the major axis along the east-west direction. The isophotes seem to have a common center (i.e. no evidence of sloshing), however the X-ray peak appears to lie to the east of the center of the isophotes. There are two bright galaxies at the center of the cluster. The brighter of the two corresponds to the X-ray peak (which unfortunately falls in a chip gap). The second galaxy is to the east, corresponding to the direction of the elongation of the surface brightness. This cluster shows a possible radio relic at 74 MHz in the VLA Low-Frequency Sky Survey (VLSS) data. The extended radio emission is northwest of the X-ray peak and extends southwest to northeast $\sim$ 165 h₇₁^-1 kpc at the resolution of the VLSS (Cohen et al. 2007).

C.43 RX J1504.1-0248/RBS 1460

RX J1504 is the cluster with the highest redshift and X-ray luminosity in HIFLUGCS, and shows the largest classical mass deposition rate. Böhringer et al. (2005) reported the results to the Chandra observation of this cluster. This cluster was originally not included in HIFLUGCS because its X-ray flux is only slightly (<20%) above the flux limit. RX J1504 appears only marginally extended in the ROSAT All-Sky Survey. Additionally the galaxy at the center of the X-ray emission is classified as AGN (Machalski & Condon 1999) and its optical spectrum shows emission lines. It was assumed that even if there is only a small AGN contribution from the central AGN to the total X-ray flux ( $\sim$ 20%), the cluster would fall below the flux limit. However, the Chandra image reveals that there is actually no significant point source emission at the center of this cluster (Böhringer et al. 2005), which argues against any significant contamination by AGN emission. Therefore, this cluster is included into HIFLUGCS. The BCG features a compact and flat-spectrum radio source (Mittal et al. 2009). This SCC cluster is one of sixteen clusters in which the BCG's central velocity dispersion is not available.

C.44 A2029

The spectra of the inner annuli fit best to non-solar metalicity ratios, but freeing ratios does not change the best-fit temperatures, so solar ratios were used for simplicity. Clarke et al. (2004) studied the core of this cluster in detail with Chandra.

C.45 A2052

The central region of this cluster requires a double thermal model out to $\sim$ 45 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 32 h₇₁^-1 kpc). Blanton et al. (2001) found prominent X-ray cavities in the original Chandra observation. They determined these cavities to be cospatial with radio lobes from the central radio source.

C.46 MKW3S/WBL 564

This SCC cluster shows some disruption in the core and bubbles to the south (Mazzotta et al. 2004). MKW3S is one of sixteen clusters in which data about the BCG's central velocity dispersion are not available. This cluster is a member of the Hercules Supercluster.

C.47 A2065

A2065 is a member of the Corona Borealis Supercluster, in projection close to the Hercules Supercluster but twice as distant. This cluster is one of four clusters on the border between SCC and WCC clusters. Its CCT is ( $\sim$ 1.3 h₇₁^-1/2 Gyr) is slightly longer than the 1 Gyr cutoff. This cluster shows an inwardly decreasing temperature profile as seen in the SCC clusters. This cluster is one of sixteen clusters in which the BCG's central velocity dispersion is not available. It is one of five clusters where the BCG peculiar velocity is more than 50% of cluster velocity dispersion. This offset suggests possible sloshing which may have disrupted the CC. Based on the Chandra data, Chatzikos et al. (2006) suggest that the cluster is involved in an unequal mass merger and that one cool core has survived the merger. Feretti & Giovannini (1994) identified a WAT $\sim$ 19 $\hbox{$^\prime$ }$ (1.6 h₇₁^-1 Mpc) south south-west of the cluster center. The jets of the WAT are bent away from the center of the cluster. In the NRAO VLA Sky Survey at 1.4 GHz (NVSS Condon et al. 1998), there appears to be a diffuse radio source $\sim$ 91 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 124 h₇₁^-1 kpc) to the southwest of the cluster center. It is unclear whether this source is associated with the central radio source.

C.48 A2063

This WCC cluster appears to have a very regular morphology in X-rays, with some hint of an elongation to the northeast. The BCG resides at the X-ray peak. The NVSS shows three bright radio sources in a line along an axis from southwest to northeast but only the center source is associated with the BCG, while the other two are cospatial with two neighbouring galaxies. As with many WCC clusters this cluster shows a flat central temperature profile and a raised central entropy K₀ > 50 h₇₁^-1/3 keV cm². This cluster is close to MKW3S.

C.49 A2142

This cluster has a double cold front (Markevitch et al. 2000). The separation between the BCG and the X-ray peak is $\sim$ 23 h₇₁^-1 kpc for this cluster, making it one of fourteen with this value >12 h₇₁^-1 kpc. This is one of sixteen clusters in which no data is available for the BCG's central velocity dispersion. It is possible this cluster hosts a radio halo, but the evidence remains dubious (Giovannini & Feretti 2000).

C.50 A2147

A2147 is a member of the Hercules Supercluster. Due to the short observing time combined with the lack of a bright core, we used a 10 $\hbox {$^{\prime \prime }$ }$ kernel when smoothing to determine the X-ray peak of this NCC cluster. There are three bright galaxies in a line near the core, of which the northernmost (the BCG) is located at the X-ray peak. This is one of the six NCC clusters in which $\dot{M}_{\rm spec} > 0$ . The X-ray morphology indicates that it is a merging cluster. The X-ray emission extends toward the south from the peak following the line of the three bright galaxies as well as extending to the southeast. There is, additionally, a sharp drop in the X-ray emission to the northwest. We argue that the observed $\dot{M}_{\rm spec}$ is not due to cooling, but results from multiple temperatures along the line of sight caused by the merger. Although the cluster has been labeled as a CC cluster in the past (e.g. Henriksen & White 1996), Sanderson et al. (2006a) found it to be an NCC cluster and likely merger system.

C.51 A2163

This well-known merging cluster contains the largest known radio halo (Feretti et al. 2001). The separation between the BCG and X-ray peak is $\sim$ 158 h₇₁^-1 kpc for this cluster, making it one of eight clusters where this value is >50 h₇₁^-1. Our measurement of $kT_{\rm vir}$ ( $\sim$ 16 keV) is higher than the value of $\sim$ 12 keV found by Markevitch & Vikhlinin (2001) with data from the original, shorter Chandra observation. However, a recent measurement by Vikhlinin et al. (2009), using the same Chandra as we, finds $kT_{\rm vir} \sim15$ keV, more consistent with our result. The difference between our result and Vikhlinin et al. (2009) is barely inconsistent within 1 $\sigma$ and is probably due to differences in the techniques used to determine $kT_{\rm vir}$ in this extremely hot cluster. This is the second most distant and hottest cluster in the HIFLUGCS sample. This is one of sixteen clusters for which data on the BCG's central velocity dispersion are not available, however, since the BCG is not cospatial with the X-ray peak so this information is not important for our analysis.

C.52 A2199

The central region of this cluster requires a double thermal model out to $\sim$ 29 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 17 h₇₁^-1 kpc).

C.53 A2204

Recently Reiprich et al. (2009) determined the temperature of this cluster out to $\sim$ r₂₀₀ using Suzaku. They find that the temperature declines all the way from 0.3 r₂₀₀ to r₂₀₀, consistent with predictions of simulations. This is one of sixteen clusters where data on the BCG's central velocity dispersion is not available.

C.54 A2244

As with A1651, Donahue et al. (2005) claim it to be a radio quiet CC cluster, but Mittal et al. (2009) detect central radio emission with a bolometric luminosity of $\sim$ $7 \times 10^{39}$ h₇₁^-2 erg s^-1. Although this is not particularly luminous, it is consistent with radio activity in other CC clusters (Mittal et al. 2009). Due to elevated entropy in the core, Donahue et al. (2005) concluded a major AGN outburst had disrupted the cooling flow. Like many WCC clusters, this cluster shows a flat temperature profile. However, we point out that the same was true of A1650 until a deeper observation revealed a slight temperature drop in the core. This is one of sixteen clusters in which the central velocity dispersion of the BCG is unavailable.

C.55 A2256

This well-known merging cluster is the only one of two NCC clusters that shows a systematic temperature decrease in the center. The temperature decrease is the largest of any NCC or WCC cluster. Surprisingly, the separation between the BCG and X-ray peak is $\sim$ 132 h₇₁^-1 kpc for this cluster, making it one of eight clusters where this value is >50 h₇₁^-1 kpc. Since this separation is quite large, the cool gas is not associated with the BCG. It is most likely this gas is the remnant of a CC (perhaps from a merging group) that has been stripped from its central galaxy. This cluster hosts both a radio halo and relic (e.g. Clarke & Ensslin 2006; Bridle & Fomalont 1976)

C.56 A2255

Due to a short exposure time and lack of a bright core, we used a 10 $\hbox {$^{\prime \prime }$ }$ kernel when smoothing the image to determine the X-ray peak. The separation between the BCG and X-ray peak is $\sim$ 72 h₇₁^-1 kpc, making it one of eight clusters where this value is >50 h₇₁^-1 kpc. This cluster BCG also has by far the largest peculiar velocity of any cluster; almost twice the velocity dispersion of the cluster. This cluster hosts both a radio halo and a relic (e.g. Feretti et al. 1997).

C.57 A3667

This well-known merging cluster shows a very sharp cold front (Vikhlinin et al. 2001b,a) and two radio relics (e.g. Roettiger et al. 1999). The separation of the BCG and X-ray peak is $\sim$ 155 h₇₁^-1 kpc for this clusters making it one of eight clusters where this value is >50 h₇₁^-1 kpc. This is the only WCC cluster with such a larger separation; however, A3667 is on the border between NCC and WCC clusters, with CCT $\sim$ 6 h₇₁^-1 Gyr.

C.58 S1101/Sérsic 159-03

Kaastra et al. (2001) provided a detailed analysis of the XMM-Newton RGS and EPIC data. Recently Werner et al. (2007) have claimed discovery of a diffuse soft excess seen by XMM-Newton and Suzaku and suggest it is of non-thermal origin. This is one of sixteen clusters in which the central velocity dispersion of the BCG is unavailable.

C.59 A2589

This WCC shows a systematic temperature drop towards the center, albeit rather flat (kT₀/kT = 0.93 and $\Gamma=-0.079$ ). Like A1650, it is on the cusp between SCC and WCC clusters. Zappacosta et al. (2006) studied this cluster with a radio-quiet BCG in detail with XMM-Newton. They find the cluster to be exceptionally relaxed with a gravitating matter profile that fits a NFW profile with $c_{\rm vir} = 6.1 \pm 0.3$ and $M_{\rm vir} = 3.3 \pm 0.3 \times 10^{14}~M_{\odot}$ ( $r_{\rm vir} = 1.74 \pm 0.05$ Mpc). They conclude that processes during halo formation act against adiabatic contraction. Additionally Buote & Lewis (2004) studied the original short Chandra observation that suffered from flaring.

Following a method to determine the residual CXB (similar to what is described in Sect 2.3), we measured the surface brightness profile out to 750 h₇₁^-1 kpc ( $\sim$ 0.5 ${r}_{\rm vir}$ ). We fit this surface brightness profile to a double- $\beta$ model and the temperature profile to a broken powerlaw. The slope of the inner kTprofile was fixed at zero and the outer kT profile fit well to a powerlaw of slope -0.36 with a break radius of 4 $\hbox{$.\mkern-4mu^\prime$ }$ 2 (204 h₇₁^-1 kpc). Using the fit to the temperature profile and double $\beta$ -model, we find a virial mass and radius of $M_{\rm vir} = 2.7 \pm 0.8 \times 10^{14}$ h₇₁^-1 $M_{\odot }$ and $r_{\rm vir} = 1.6 \pm0.2~h_{71}^{-1}$ Mpc respectively, consistent with the results of Zappacosta et al. (2006).

C.60 A2597

McNamara et al. (2001) analyzed the original, short, flared observation of A2597, noting the ghost bubbles. Morris & Fabian (2005) found high spectral mass deposition rates from the XMM-Newton EPIC and RGS consistent with $\sim$ 100 $M_{\odot }$ yr^-1 down to almost 0 keV, although the improvement to the spectral fits of the RGS data from the addition of a cooling flow model is marginal. The long Chandra ACIS observation shows a mass deposition rate of $\sim$ 150 $M_{\odot }$ yr^-1 down to $\sim$ 1.3 keV and dropping to $\sim$ 10 $M_{\odot }$ yr^-1 down to $\sim$ 0 keV.

C.61 A2634

This WCC cluster contains the WAT source 3C465. There is a pair of galaxies (NGC 7720) located at the X-ray peak. An extended bright X-ray halo (radius = $\sim$ $12\hbox{$^{\prime\prime}$ }$ ), much brighter than the ICM emission, is cospatial with the galaxy pair. The halo seems to be associated with the larger southern galaxy. A2634 is the only CC cluster in the sample with $\dot{M}_{{\rm spec}}> \dot{M}_{{\rm classical}}$ . The temperature profile shows a sudden drop at $\sim$ 2 $\hbox{$.\mkern-4mu^\prime$ }$ 7 ( $\sim$ 100 h₇₁^-1 kpc). Other than NGC 7720, there is no obvious core in A2634 and the elongation of the ICM to the southwest is consistent with a merging cluster. Moreover the inverted temperature profile is more common in NCC clusters than in WCC clusters. We interpret the short cooling time and low $\dot{M}_{\rm classical}$ as a cool core that has either been disrupted or is in the process of being destroyed by a merger. $\dot{M}_{\rm spec}$ may reflect the original mass deposition rate, but probably is strongly affected by multitemperature components along the line of sight in a merging system.

C.62 A2657

This WCC cluster has a slight increase in temperature in the central region. The Chandra image shows a cluster similar to e.g. A1650 and A2244. The central emission peak is clearly visibly but is not as sharply peaked as in SCC clusters. The overall ICM appears to be quite round, with some sloshing features (differently centered X-ray isophotes at different radii) in the central region.

C.63 A4038

The distance between the BCG and X-ray peak is $\sim$ 12.4 h₇₁^-1 kpc for this cluster making it one of fourteen clusters where this separation is >12 h₇₁^-1 kpc. This cluster hosts a radio relic, close to but not connected to the central radio galaxy (Slee & Roy 1998).

C.64 A4059

The central region of this cluster requires a double thermal model out to $\sim$ 22 $\hbox {$^{\prime \prime }$ }$ ( $\sim$ 20 h₇₁^-1 kpc).

Table 2: Observational parameters.

Table 3: Derived parameters.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.