Sabrina Grandi - Academia.edu (original) (raw)
Papers by Sabrina Grandi
Astronomy & Astrophysics, 2016
Astronomy & Astrophysics, 2019
Context. The hot plasma in a galaxy cluster is expected to be heated to high temperatures through... 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...
The Astrophysical Journal
In the paper ``A Flux-limited Sample of Bright Clusters of Galaxies from the Southern Part of the... 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:
Multi-object spectroscopic observations of A545 were carried out at the TNG telescope in October ... 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
The Astrophysical Journal, 2001
Astronomy & Astrophysics, 2011
Astronomy & Astrophysics, 2004
Astronomy & Astrophysics, 2010
Astronomy and Astrophysics, 2009
Astronomy & Astrophysics, 2004
Astronomy and Astrophysics, 2002
On May 27th 2010, the Italian astronomical community learned with concern that the National Insti... 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 ...
Astronomy & Astrophysics, 2014
Astronomy & Astrophysics
Aims. We present the results of a joint XMM-Newton and NuSTAR observation (200 ks) of the galaxy ... 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...
We present a theoretical model which aims at predicting the clustering properties of X-ray cluste... 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.
The crisis of the standard cooling flow model brought about by Chandra and XMM-Newton observation... 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...
Astronomy & Astrophysics
We present the first metal abundance profiles for a representative sample of massive clusters. Ou... 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...
We present the first metal abundance profiles for a representative sample of massive clusters. Ou... 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...
Astronomy & Astrophysics
Context. Nearby clusters of galaxies, z ≲ 0.1, are cosmic structures still under formation. Under... 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...
Astronomy & Astrophysics
Galaxy clusters are the endpoints of structure formation and are continuously growing through the... 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...
Astronomy & Astrophysics, 2016
Astronomy & Astrophysics, 2019
Context. The hot plasma in a galaxy cluster is expected to be heated to high temperatures through... 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...
The Astrophysical Journal
In the paper ``A Flux-limited Sample of Bright Clusters of Galaxies from the Southern Part of the... 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:
Multi-object spectroscopic observations of A545 were carried out at the TNG telescope in October ... 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
The Astrophysical Journal, 2001
Astronomy & Astrophysics, 2011
Astronomy & Astrophysics, 2004
Astronomy & Astrophysics, 2010
Astronomy and Astrophysics, 2009
Astronomy & Astrophysics, 2004
Astronomy and Astrophysics, 2002
On May 27th 2010, the Italian astronomical community learned with concern that the National Insti... 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 ...
Astronomy & Astrophysics, 2014
Astronomy & Astrophysics
Aims. We present the results of a joint XMM-Newton and NuSTAR observation (200 ks) of the galaxy ... 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...
We present a theoretical model which aims at predicting the clustering properties of X-ray cluste... 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.
The crisis of the standard cooling flow model brought about by Chandra and XMM-Newton observation... 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...
Astronomy & Astrophysics
We present the first metal abundance profiles for a representative sample of massive clusters. Ou... 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...
We present the first metal abundance profiles for a representative sample of massive clusters. Ou... 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...
Astronomy & Astrophysics
Context. Nearby clusters of galaxies, z ≲ 0.1, are cosmic structures still under formation. Under... 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...
Astronomy & Astrophysics
Galaxy clusters are the endpoints of structure formation and are continuously growing through the... 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...