Clusters In the Zone of Avoidance
The CIZA team:
Project overview:
The CIZA project (Clusters In the Zone of
Avoidance) is the first systematic X-ray search for clusters of
galaxies behind the Milky Way. CIZA uses a combined X-ray/optical/NIR
approach to identify clusters of galaxies at |b| < 20 deg, i.e., in a
region of the sky that has traditionally been excluded from earlier
cluster catalogues because of massive obscuration and extinction
problems. So far, CIZA has identified and spectroscopically confirmed
101 galaxy clusters in what used to be the zone of avoidance; 74 (73%)
of these are new discoveries. An additional 10 clusters have been
confirmed in imaging observations and await spectroscopic observation.
The sample:
The following figure shows the column density of neutral Hydrogen in the
Galactic plane region. Regions of very high nH close to the Galactic center
are impenetrable even to X-rays. At moderate Galactic latitude, however,
and in the direction of the Galactic anticenter X-ray vision allows us to
effectively look through the Milky Way in search of extragalactic objects
such as clusters of galaxies.
Weather permitting we shall finish the compilation of a statistically
complete subset of the X-ray brightest CIZA clusters by mid 2001. We intend
to publish the resulting subsample before the end of the year.
CIZA publications (by the CIZA team):
CIZA - The First Systematic X-ray Search for Clusters of Galaxies
Behind the Milky Way 2000, in Mapping the Hidden Universe: The
Universe Behind the Milky Way / The Universe in HI,
Kraan-Korteweg, Henning, Andernach (eds), ASP
Conference Series, Vol 218, p79
(page last updated by H. Ebeling, January 4, 2001)
