%0 Journal Article
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%@dissemination WEBSCI; PORTALCAPES.
%@nexthigherunit 8JMKD3MGPCW/3ETR8EH
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%3 La Barbera_The nature.pdf
%X We use SDSS-DR4 photometric and spectroscopic data out to redshift z similar to 0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of 25 fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample, and the main pitfalls are also discussed. The spatial density of FGs, estimated via the V/V-MAX test, is 2.83 x 10(-6) h(75)(3) Mpc(-3) for L-X > 0.89 x 10(42) h(75)(-2) erg s(-1) consistent with Vikhlinin et al., who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same data set. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a(4) and internal color gradients. Furthermore, examination of stellar populations shows that our 25 FGs have similar ages, metallicities, and alpha-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the universe.
%@mirrorrepository sid.inpe.br/mtc-m18@80/2008/03.17.15.17.24
%8 Apr.
%N 137
%T The nature of fossil galaxy groups: are they really fossils?
%@secondarytype PRE PI
%K digital sky survey, rosat all-sky, active galactic nuclei, color-magnitude relation, band optical-properties, x-ray-properties, cluster survey, data release, stellar populations, elliptic galaxies.
%@group
%@group DAS-CEA-INPE-MCT-BR
%@secondarykey INPE--PRE/
%@issn 0004-6256
%2 sid.inpe.br/mtc-m18@80/2009/07.20.12.40.53
%@affiliation Osserv Astron Capodimonte, INAF, I-80131 Naples, Italy
%@affiliation VSTceN, I-80131 Naples, Italy
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Inst Astrofis Canarias, Tenerife, Spain
%@affiliation Osserv Astron Capodimonte, INAF, I-80131 Naples, Italy
%@affiliation Univ Hawaii, Inst Astron, Honolulu, HI 96822 US
%B Astronomical Journal
%P 3942-3960
%4 sid.inpe.br/mtc-m18@80/2009/07.20.12.40
%D 2009
%V 137
%@doi 10.1088/0004-6256/137/4/3942
%A La Barbera, F.,
%A Carvalho, Reinaldo Ramos,
%A de la Rosa, I. G.,
%A Sorrentino, G.,
%A Gal, R.,
%A Kohl-Moreira, J. L.,
%@area CEA