The X-ray Zurich Environmental Study (X-ZENS). II. X-ray observations of the diffuse intragroup medium in galaxy groups
- Physics Department, Wolfgang-Pauli-Strasse 27, ETH-Zürich, CH-8093, Zürich (Switzerland)
- Department of Physics, Gustaf Hällströmin katu 2a, FI-00014, University of Helsinki (Finland)
- Institute for the Physics and Mathematics of the universe (IPMU), University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba 277-8568 (Japan)
- Astronomy Center, Dept. of Physics and Astronomy, University of Sussex, Falmer, Brighton BN1 9QH (United Kingdom)
We present the results of a pilot XMM-Newton and Chandra program aimed at studying the diffuse intragroup medium (IGM) of optically selected nearby groups from the Zurich ENvironmental Study (ZENS) catalog. The groups are in a narrow mass range about 10{sup 13} M{sub ⊙}, a mass scale at which the interplay between the IGM and the group member galaxies is still largely unprobed. X-ray emission from the IGM is detected in the energy band 0.5–2 keV with flux ⩽10{sup −13} erg s{sup −1} cm{sup −2}, which is one order of magnitude fainter than for typical ROSAT groups (RASS). For many groups, we set upper limits on the X-ray luminosity, indicating that the detections are likely probing the upper envelope of the X-ray emitting groups. We find that weighting the group halo mass by the fraction of the total stellar mass locked in the bulge galaxy components might reduce the bias of mass estimates based on the total optical luminosity with respect to the X-ray mass estimates, (consistent with Andreon, at larger mass scales). We measure a stellar mass fraction with a median value of about 1%, with a contribution from the most massive galaxies between 30% and 50%. Optical and X-ray data often give complementary answers concerning the dynamical state of the groups, and are essential for a complete picture of the group system. Extending this pilot program to a larger sample of groups is necessary to unveil any imprint of interaction between member galaxies and IGM in halo potentials of key importance for environmentally driven galactic evolution.
- OSTI ID:
- 22886986
- Journal Information:
- Astrophysical Journal, Vol. 819, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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