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Session 53 - The X Clusters: Cooling Flows.
Display session, Thursday, January 08
Exhibit Hall,

[53.03] The Nature of the Large Scale X-ray Emission around Abell Clusters

T. Miyaji (Astrophysikalisches Inst. Potsdam), R. Kneissl (MPI fuer Astrophysik)

Soltan et al. (1996) found a significant positive component extending up to several degrees in their angular cross-correlation function (CCF) between the ROSAT All-Sky Survey (RASS) diffuse soft X-ray (E\sim 1keV) map and Abell clusters. To explain this, one model they have suggested consists of a 20h_50^-1 Mpc-scale X-ray emitting hot gas halo associated with each Abell cluster.

In order to constrain the nature of this extended component, we have made CCF studies between Abell clusters and hard X-ray maps observed with HEAO-1 A2 as well as the microwave map observed with COBE DMR. Our preliminary analysis shows that there also exists an extended component in the hard X-ray - Abell cluster CCF at a similar scale, indicating that the spectrum of the extended component is harder than a thermal spectrum for gas temperatures of typical clusters. A robust upper limit to the Sunyaev-Zel'dovich decrement set by the COBE DMR - Abell cluster CCF excludes an extended gas halo model with temperatures kT>1 keV. Combining these results, we can rule out any gas origin with a smooth profile for the extended component. A possibility consistent with the data is that X-ray emitting field AGNs clustered with Abell clusters give rise to the extended CCF signal.

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Program listing for Thursday