428 research outputs found
Beppo-SAX Observations of Galaxy Clusters
The high spatial resolution of the MECS experiment on board Beppo-SAX has
encouraged a few scientists, including the author, to perform observations of
galaxy clusters. Results from the analysis of the first few observed objects
are encouraging. After having reviewed the Beppo-SAX observing program for
galaxy clusters and referenced contributions to these proceedings by other
authors on the same topic, I present results from the analysis of the Perseus
cluster.Comment: 4 pages, 4 Postscript figures included. To appear in the proceedings
of the ``Active X-ray Sky: Results from BeppoSAX and Rossi-XTE'
The evolution of the spatially-resolved metal abundance in galaxy clusters up to z=1.4
We present the combined analysis of the metal content of 83 objects in the
redshift range 0.09-1.39, and spatially-resolved in the 3 bins (0-0.15,
0.15-0.4, >0.4) R500, as obtained with similar analysis using XMM-Newton data
in Leccardi & Molendi (2008) and Baldi et al. (2012). We use the pseudo-entropy
ratio to separate the Cool-Core (CC) cluster population, where the central gas
density tends to be relatively higher, cooler and more metal rich, from the
Non-Cool-Core systems. The average, redshift-independent, metal abundance
measured in the 3 radial bins decrease moving outwards, with a mean metallicity
in the core that is even 3 (two) times higher than the value of 0.16 times the
solar abundance in Anders & Grevesse (1989) estimated at r>0.4 R500 in CC (NCC)
objects. We find that the values of the emission-weighted metallicity are
well-fitted by the relation at given radius. A
significant scatter, intrinsic to the observed distribution and of the order of
0.05-0.15, is observed below 0.4 R500. The nominal best-fit value of
is significantly different from zero in the inner cluster regions () and in CC clusters only. These results are confirmed also with a
bootstrap analysis, which provides a still significant negative evolution in
the core of CC systems (P>99.9 per cent). No redshift-evolution is observed
when regions above the core (r > 0.15 R500) are considered. A reasonable good
fit of both the radial and redshift dependence is provided from the functional
form , with in CC clusters
and for NCC systems. Our results
represent the most extensive study of the spatially-resolved metal distribution
in the cluster plasma as function of redshift.Comment: 5 pages. Research Note accepted for publication in A&
- …