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Context. The hot plasma in a galaxy cluster is expected to be heated to high temperatures through shocks and adiabatic compression. The thermodynamical properties of the gas encode information on the processes leading to the... more
Context. The hot plasma in a galaxy cluster is expected to be heated to high temperatures through shocks and adiabatic compression. The thermodynamical properties of the gas encode information on the processes leading to the thermalization of the gas in the cluster’s potential well and on non-gravitational processes such as gas cooling, AGN feedback, shocks, turbulence, bulk motions, cosmic rays and magnetic field. Aims. In this work we present the radial profiles of the thermodynamic properties of the intracluster medium (ICM) out to the virial radius for a sample of 12 galaxy clusters selected from the Planck all-sky survey. We determine the universal profiles of gas density, temperature, pressure, and entropy over more than two decades in radius, from 0.01R500 to 2R500. Methods. We exploited X-ray information from XMM-Newton and Sunyaev-Zel’dovich constraints from Planck to recover thermodynamic properties out to 2R500. We provide average functional forms for the radial dependenc...
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In the paper ``A Flux-limited Sample of Bright Clusters of Galaxies from the Southern Part of the ROSAT All-Sky Survey: The Catalog and logN-logS'' by S. De Grandi, H. Böhringer, L. Guzzo, S. Molendi, G. Chincarini, C. Collins, R.... more
In the paper ``A Flux-limited Sample of Bright Clusters of Galaxies from the Southern Part of the ROSAT All-Sky Survey: The Catalog and logN-logS'' by S. De Grandi, H. Böhringer, L. Guzzo, S. Molendi, G. Chincarini, C. Collins, R. Cruddace, D. Neumann, S. Schindler, P. Schuecker, and W. Voges (ApJ, 514, 148 [1999]), eight objects in Table 1 with positive declinations are reported with negative declinations. The corrected objects are shown below:
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Multi-object spectroscopic observations of A545 were carried out at the TNG telescope in October 2009. We used DOLORES/MOS with the LR-B Grism 1, yielding a dispersion of 187Å/mm. We used the new 2048x2048pixels E2V CCD, with a pixel size... more
Multi-object spectroscopic observations of A545 were carried out at the TNG telescope in October 2009. We used DOLORES/MOS with the LR-B Grism 1, yielding a dispersion of 187Å/mm. We used the new 2048x2048pixels E2V CCD, with a pixel size of 13.5um. In total, we observed 4 MOS masks for a total of 142 slits. We acquired three exposures of 1200s
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On May 27th 2010, the Italian astronomical community learned with concern that the National Institute for Astrophysics (INAF) was going to be suppressed, and that its employees were going to be transferred to the National Research Council... more
On May 27th 2010, the Italian astronomical community learned with concern that the National Institute for Astrophysics (INAF) was going to be suppressed, and that its employees were going to be transferred to the National Research Council (CNR). It was not clear if this applied to ...
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Aims. We present the results of a joint XMM-Newton and NuSTAR observation (200 ks) of the galaxy cluster Abell 523 at z = 0.104. The peculiar morphology of the cluster radio halo and its outlier position in the radio power P(1.4 GHz) –... more
Aims. We present the results of a joint XMM-Newton and NuSTAR observation (200 ks) of the galaxy cluster Abell 523 at z = 0.104. The peculiar morphology of the cluster radio halo and its outlier position in the radio power P(1.4 GHz) – X-ray luminosity plane make it an ideal candidate for the study of radio and X-ray correlations and for the search of inverse Compton (IC) emission. Methods. We constructed bi-dimensional maps for the main thermodynamic quantities (i.e., temperature, pressure and entropy) derived from the XMM observations to describe the physical and dynamical state of the cluster’s intracluster medium (ICM) in detail. We performed a point-to-point comparison in terms of surface brightness between the X-ray and radio emissions to quantify their morphological discrepancies. Making use of NuSTAR’s unprecedented hard X-ray focusing capability, we looked for IC emission both globally and locally after properly modeling the purely thermal component with a multi-temperature...
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We present a theoretical model which aims at predicting the clustering properties of X-ray clusters in flux-limited surveys for different cosmological scenarios. The model uses the theoretical and empirical relations between mass,... more
We present a theoretical model which aims at predicting the clustering properties of X-ray clusters in flux-limited surveys for different cosmological scenarios. The model uses the theoretical and empirical relations between mass, temperature and X-ray luminosity, and fully accounts for the redshift evolution of the underlying dark matter clustering and cluster bias factor. We apply the model to the RASS1 Bright Sample and to the XBACs catalogue. The results show that the Einstein-de Sitter models display too low a correlation length, while models with a matter density parameter Omega_0m=0.3 (with or without a cosmological constant) are successful in reproducing the observed clustering.
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The crisis of the standard cooling flow model brought about by Chandra and XMM-Newton observations of galaxy clusters has led to the development of several models that explore different heating processes in order to assess whether they... more
The crisis of the standard cooling flow model brought about by Chandra and XMM-Newton observations of galaxy clusters has led to the development of several models that explore different heating processes in order to assess whether they can quench the cooling flow. Among the most appealing mechanisms are thermal conduction and heating through buoyant gas deposited in the intracluster medium (ICM) by active galactic nuclei (AGNs). We combine Virgo/M87 observations of three satellites (Chandra, XMM-Newton, and BeppoSAX) to inspect the dynamics of the ICM in the center of the cluster. Using the spectral deprojection technique, we derive the physical quantities describing the ICM and determine the extra heating needed to balance the cooling flow, assuming that thermal conduction operates at a fixed fraction of the Spitzer value. We assume that the extra heating is due to buoyant gas, and we fit the data using the model developed by Ruszkowski and Begelman. We derive a scale radius for th...
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We present the first metal abundance profiles for a representative sample of massive clusters. Our measurements extend to R500 and are corrected for a systematic error plaguing previous outskirt estimates. Our profiles flatten out at... more
We present the first metal abundance profiles for a representative sample of massive clusters. Our measurements extend to R500 and are corrected for a systematic error plaguing previous outskirt estimates. Our profiles flatten out at large radii, admittedly not a new result, however the radial range and representative nature of our sample extends its import well beyond previous findings. We find no evidence of segregation between cool-core and non-cool-core systems beyond ∼0.3 R500, implying that, as was found for thermodynamic properties, the physical state of the core does not affect global cluster properties. Our mean abundance within R500 shows a very modest scatter, < 15%, suggesting the enrichment process must be quite similar in all these massive systems. This is a new finding and has significant implications for feedback processes. Together with results from the thermodynamic properties presented in a previous X-COP paper, it affords a coherent picture in which feedback e...
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We present the first metal abundance profiles for a representative sample of massive clusters. Our measures extend to R500 and are corrected for a systematic error plaguing previous outskirt estimates. Our profiles flatten out at large... more
We present the first metal abundance profiles for a representative sample of massive clusters. Our measures extend to R500 and are corrected for a systematic error plaguing previous outskirt estimates. Our profiles flatten out at large radii, admittedly not a new result, however the radial range and representative nature of our sample extends its import well beyond previous findings. We find no evidence of segregation between cool-core and non-cool-core systems beyond ∼ 0.3 R500, implying that, as was found for thermodynamic properties (Ghirardini et al. 2019), the physical state of the core does not affect global cluster properties. Our mean abundance within R500 shows a very modest scatter, <15%, suggesting the enrichment process must be quite similar in all these massive systems. This is a new finding and has significant implications on feedback processes. Together with results from thermodynamic properties presented in a previous X-COP paper, it affords a coherent picture whe...
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Context. Nearby clusters of galaxies, z ≲ 0.1, are cosmic structures still under formation. Understanding the thermodynamic properties of merging clusters can provide crucial information on how they grow in the local universe. Aims. A... more
Context. Nearby clusters of galaxies, z ≲ 0.1, are cosmic structures still under formation. Understanding the thermodynamic properties of merging clusters can provide crucial information on how they grow in the local universe. Aims. A detailed study of the intra-cluster medium (ICM) properties of un-relaxed systems is essential to understand the fate of in-falling structures and, more generally, the virialization process. Methods. We analyzed a mosaic of XMM-Newton observations (240 ks) of the Lyra system (z ∼ 0.067) that shows a complex dynamical state. Results. We find the main cluster RXC J1825.3+3026 to be in a late merger phase, whereas its companion CIZA J1824.1+3029 is a relaxed cool-core cluster. We estimate a mass ratio of ∼1 : 2 for the pair. No diffuse X-ray emission is found in the region between them, indicating that these clusters are in a pre-merger phase. We found evidence of a galaxy group infalling on RXC J1825.3+3026 in an advanced state of disruption. The SG, one...
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Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized,... more
Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized, mainly in the form of kinetic motions (turbulence, bulk motions). Measuring the level of non-thermal pressure support is necessary to understand the processes leading to the virialization of the gas within the potential well of the main halo and to calibrate the biases in hydrostatic mass estimates. We present high-quality measurements of hydrostatic masses and intracluster gas fraction out to the virial radius for a sample of 13 nearby clusters with available XMM-Newton and Planck data. We compare our hydrostatic gas fractions with the expected universal gas fraction to constrain the level of non-thermal pressure support. We find that hydrostatic masses require little correction and infer a median non-thermal pressure fraction of ∼6% and ∼10% at R50...
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Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized,... more
Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized, mainly in the form of kinetic motions (turbulence, bulk motions). Measuring the level of non-thermal pressure support is necessary to understand the processes leading to the virialization of the gas within the potential well of the main halo and to calibrate the biases in hydrostatic mass estimates. We present high-quality measurements of hydrostatic masses and intracluster gas fraction out to the virial radius for a sample of 12 nearby clusters with available XMM-Newton and Planck data. We compare our hydrostatic gas fractions with the expected universal gas fraction to constrain the level of non-thermal pressure support. We find that hydrostatic masses require little correction and infer a median non-thermal pressure fraction of ∼ 6% and ∼ 10% at R...
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We present the final data from the spectroscopic survey of the ROSAT-ESO Flux-Limited X-ray (REFLEX) catalogue of galaxy clusters. The REFLEX survey covers 4.24 steradians (34% of the entire sky) below a declination +2.50° and at high... more
We present the final data from the spectroscopic survey of the ROSAT-ESO Flux-Limited X-ray (REFLEX) catalogue of galaxy clusters. The REFLEX survey covers 4.24 steradians (34% of the entire sky) below a declination +2.50° and at high galactic latitude (|b|&amp;amp;amp;lt;20°). The full survey includes 447 galaxy clusters with a median redshift of 0.08 and is better than 90% complete to
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We present, for the first time, a comprehensive analysis of nearby galaxy clusters observed with BeppoSAX. The better spatial resolution of the BeppoSAX data when compared to the ASCA data allow us to improve substantially on similar... more
We present, for the first time, a comprehensive analysis of nearby galaxy clusters observed with BeppoSAX. The better spatial resolution of the BeppoSAX data when compared to the ASCA data allow us to improve substantially on similar studies conducted with ASCA. Our main results can be summarized as follows. Merging clusters can exhibit very different temperature profiles, on the contrary cooling-flow clusters show evidence of a universal temperature profile. Merging clusters have flat Fe profiles while cooling-flow clusters have very strong Fe gradients.
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ABSTRACT
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ABSTRACT
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We review all the BeppoSAX results relative to the search for additional nonthermal components in the spectra of clusters of galaxies. In particular, our MECS data analysis of A2199 does not confirm the presence of the nonthermal excess... more
We review all the BeppoSAX results relative to the search for additional nonthermal components in the spectra of clusters of galaxies. In particular, our MECS data analysis of A2199 does not confirm the presence of the nonthermal excess reported by Kaastra et al. (1999). A new observation of A2256 seems to indicate quite definitely that the nonthermal fluxes detected in
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We aim to review the internal structure and dynamics of the Abell 1351 cluster, shown to host a radio halo with a quite irregular shape. Our analysis is based on radial velocity data for 135 galaxies obtained at the Telescopio Nazionale... more
We aim to review the internal structure and dynamics of the Abell 1351 cluster, shown to host a radio halo with a quite irregular shape. Our analysis is based on radial velocity data for 135 galaxies obtained at the Telescopio Nazionale Galileo. We combine galaxy velocities and positions to select 95 cluster galaxy members and analyse the internal dynamics of the whole cluster. We also examine X-ray data retrieved from Chandra and XMM archives. We measure the cluster redshift, =0.325, the line-of-sight (LOS) velocity dispersion, \sigma_v~1500 km/s, and the X-ray temperature, kT~9 keV. From both X-ray and optical data independently, we estimate a large cluster mass, in the 1--4 $10^{15}$ M$_\odot$ range. We attribute the extremely high value of \sigma_v to the bimodality in the velocity distribution. We find evidence of a significant velocity gradient and optical 3D substructure. The X-ray analysis also shows many features in favour of a complex cluster structure, probably supporting...
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We review all the BeppoSAX results relative to the search for additional nonthermal components in the spectra of clusters of galaxies. In particular, our MECS data analysis of A2199 does not confirm the presence of the nonthermal excess... more
We review all the BeppoSAX results relative to the search for additional nonthermal components in the spectra of clusters of galaxies. In particular, our MECS data analysis of A2199 does not confirm the presence of the nonthermal excess reported by Kaastra et al. (1999). A new observation of A2256 seems to indicate quite definitely that the nonthermal fluxes detected in Coma and A2256 are due to a diffuse nonthermal mechanism involving the intracluster medium. We report marginal evidence (~3\sigma) for a nonthermal excess in A754 and A119, but the presence of point sources in the field of view of the PDS makes unlikely a diffuse interpretation.
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We carried out a detailed study of the Si, Fe and Ni abundances in the cool cores of a representative sample of local galaxy clusters using XMM-Newton data. We first evaluated the systematic errors on the abundance measurements that are... more
We carried out a detailed study of the Si, Fe and Ni abundances in the cool cores of a representative sample of local galaxy clusters using XMM-Newton data. We first evaluated the systematic errors on the abundance measurements that are related to the instruments, the plasma codes and the spectral modeling. We then used the Si/Fe and Ni/Fe abundance ratios to revisit the relative contribution of type Ia and core-collapsed supernovae to the enrichment process taking into account the uncertainties on both the measured abundances and the current theoretical supernovae yields. WFXT will push forward sensibly abundance studies of the kind described in this paper: first by increasing dramatically the number of objects with adequate photon statistics and secondly, by means of an improved spatial resolution will allows us to study galaxy cluster cores at redshifts up to 1.
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The authors describe the construction of an X-ray selected, flux limited sample of 111 clusters of galaxies from the ESO Key Programme "A Redshifts Survey of ROSAT Clusters of Galaxies". First, the authors discuss a new method -... more
The authors describe the construction of an X-ray selected, flux limited sample of 111 clusters of galaxies from the ESO Key Programme "A Redshifts Survey of ROSAT Clusters of Galaxies". First, the authors discuss a new method - "the steepness ratio technique" (SRT) - which they have used to derive X-ray fluxes for the sources. Then, the authors describe the selection criteria applied to the ESO sample in order to maximize the degree of completeness of the flux limited sample. On the basis of a thorough analysis of the data, they estimate the sample to be complete at the >97% level. Finally, the authors derive a log N - log S distribution with a limiting flux of ≡3×10-12 erg s-1cm2 in the 0.5 - 0.2 keV band.
The radial temperature profile of the X-ray emitting intra-cluster medium (ICM) is a key observable in determining the total mass of galaxy clusters. To date different studies (ROSAT, ASCA and BeppoSAX) have found conflicting results... more
The radial temperature profile of the X-ray emitting intra-cluster medium (ICM) is a key observable in determining the total mass of galaxy clusters. To date different studies (ROSAT, ASCA and BeppoSAX) have found conflicting results regarding temperature gradients in clusters and no firm results have been obtained from recent XMM-Newton analysis of a few pointed observations of clusters. We propose
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Detailed studies of A545 at radio, optical and X-ray wavelengths point to a system undergoing a major merger. The unique discovery of an extended stellar halo resembling that of a cD but with no associated BCG is particularly intriguing... more
Detailed studies of A545 at radio, optical and X-ray wavelengths point to a system undergoing a major merger. The unique discovery of an extended stellar halo resembling that of a cD but with no associated BCG is particularly intriguing as it suggests this system may be undergoing a critical dynamic phase that is rarely observed. The available XMM data while
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We review observations on the chemical enrichment of the intracluster medium (ICM) performed using BeppoSAX MECS data. The picture emerging is that non-cooling flow clusters have flat metallicity profiles, whereas a strong enhancement in... more
We review observations on the chemical enrichment of the intracluster medium (ICM) performed using BeppoSAX MECS data. The picture emerging is that non-cooling flow clusters have flat metallicity profiles, whereas a strong enhancement in the abundance is found in the central regions of the cooling flow clusters. All the non-cooling flow clusters present evidence of recent merger activity suggesting that
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We present results from a BeppoSAX observation of the cooling flow cluster Abell 2029. The broad band spectrum (2-35 keV) of the cluster, when fitted with a model including a cooling flow component and a one temperature thermal component,... more
We present results from a BeppoSAX observation of the cooling flow cluster Abell 2029. The broad band spectrum (2-35 keV) of the cluster, when fitted with a model including a cooling flow component and a one temperature thermal component, yields a temperature of 8.3+/-0.2 keV and a metal abundance of 0.46+/-0.03 in solar units, for the latter. No evidence of
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Deep photometric observations in three colours of the cluster A 496 show that the luminosity function is bimodal with a deep gap at g ~ 19.0. That is there is a net separation between E/SO galaxies that are nicely fitted by a gaussian... more
Deep photometric observations in three colours of the cluster A 496 show that the luminosity function is bimodal with a deep gap at g ~ 19.0. That is there is a net separation between E/SO galaxies that are nicely fitted by a gaussian distribution curve and the dwarfs that better match a Shechter function. This is the first cluster observed