arXiv subjects

Sabrina De Grandi

Publications and source records attributed to Sabrina De Grandi.

23 records · Page 2Linked to original sources

arXiv1999

Spatially resolved spectroscopy of the cooling flow cluster PKS 0745-191 with BeppoSAX

We present results from a BeppoSAX observation of the cooling flow cluster PKS 0745-191 (z=0.1028). By performing spatially resolved spectroscopy, we find that the projected temperature profile is consistent with being constant. We can rule out, at more than the 99% confidence level, a temperature decrement of a factor 2 when going from the cluster core out to 1.2 Mpc. On the contrary, the projected metal abundance is found to drop from 0.4 (solar units) within the cluster core to 0.2 (solar units) at radii larger than 300 kpc, this decrement is significant at more than the 99.9% confidence level.

astro-ph↗

arXiv1999

A BeppoSAX observation of the merging cluster Abell 3266

We present results from a BeppoSAX observation of the rich cluster Abell 3266. The broad band spectrum (2-50 keV) of the cluster, when fitted with an optically thin thermal emission model, yields a temperature of 8.1 +/- 0.2 keV and a metal abundance of 0.17 +/- 0.02 in solar units, and with no evidence of a hard X-ray excess in the PDS spectrum. By performing a spatially resolved spectral analysis we find that the projected temperature drops with increasing radius, going from ~ 10 keV at the cluster core to ~ 5 keV at about 1.5 Mpc. Our BeppoSAX temperature profile is in good agreement with the ASCA temperature profile of Markevitch et al. (1998). From our two-dimensional temperature map we find that the gradient is observed in all azimuthal directions. The temperature gradient may have been caused by a recent merger event also responsible for a velocity dispersion gradient measured in the optical band. The projected metal abundance profile and two-dimensional map are both consistent with being constant.

astro-ph↗

arXiv1999

A BeppoSAX observation of the cooling flow cluster Abell 2029

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 a hard X-ray excess is found in the PDS spectrum. By performing a spatially resolved spectral analysis we find that the projected temperature and abundance drop with increasing radius, going from about 8 keV and 0.5 (solar units) at the cluster core to about 5 keV and 0.2 (solar units) at about 1.2 Mpc.

astro-ph↗

arXiv1999

Predicting the Clustering of X-Ray Clusters

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.

astro-ph↗

arXiv1998

The Composite Luminosity Function of A496

Deep photometric observations in three colours of the cluster A 496 show that the luminosity function is bimodal with a deep gap at g about 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 and reduced out of a sample of 19 clusters which we have in our program. However comparison with the data of Virgo and Coma might suggest a correlation between cluster morphology and amplitude of the two distribution: Normal and dwarf population. This would have strong implication for the understanding of cluster formation and evolution so that we are pursuing the estimate of the LF in various colours and to faint magnitudes both for low and high redshift clusters.

astro-ph↗