A2125 and its environs: Evidence for an X-ray-emitting hierarchical superstructure

Q. Daniel Wang, Andrew J. Connolly, Robert J. Brunner

Research output: Contribution to journalArticlepeer-review


Based on a deep ROSAT/PSPC observation, we reveal an elongated complex of extended X-ray-emitting objects in and around the galaxy cluster A2125. Multicolor optical imaging of galaxies in the field suggests that this complex represents a hierarchical superstructure spanning ∼11 h50-1 Mpc at the redshift ∼0.247. The multiple peak X-ray morphology and large blue galaxy fraction of A2125 indicate that the cluster is undergoing a coalescence of subunits. The superstructure contains two additional clusters, projected at distances of only 3 and 4.3 h50-1 Mpc from A2125. The most interesting feature is, however, the low surface brightness X-ray emission from a moderate galaxy concentration away from individual clusters. The emission likely arises in a hot (∼107 K) intergalactic medium, as predicted in N-body/hydro simulations of structure formation.

Original languageEnglish (US)
Pages (from-to)L13-L16
JournalAstrophysical Journal
Issue number1 PART II
StatePublished - 1997
Externally publishedYes


  • Cosmology: observations
  • Galaxies: clusters: general
  • Galaxies: clusters: individual (A2125)
  • Large-scale structure of universe
  • X-rays: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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