Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994aas...185.7407w&link_type=abstract
American Astronomical Society, 185th AAS Meeting, #74.07; Bulletin of the American Astronomical Society, Vol. 26, p.1428
Astronomy and Astrophysics
Astronomy
Scientific paper
One of the most persistent problems concerning cooling flows is the ultimate repository of the cooling gas. Recently, White et al. (1991) have found evidence for excess soft X-ray absorption in the spectra of a sample of cluster cooling flows observed with the Einstein SSS. The typical excess columns of cold material (in excess to the galactic column N_H) are Delta N_H ~ 10(21) cm(-2) . When these columns are accumulated over the area of the cooling flow, they imply the presence of very large quantities of cold absorbing material (Mcold ~ 10(11) --10(12) Msun). This soft X-ray absorption could represent the first direct evidence for the large amounts of cooled material which current cooling flow models predict. We will present results from the analysis of a 45 ksec ASCA observation of the bright, relatively nearby (z=0.0767) cooling flow cluster A2029. Our preliminary analysis confirms both the strong cooling flow (dot M ~ 370 Msun yr(-1) ) as well as the presence of excess absorption at a level ~ 5 times the standard galactic column. The spectrum is reasonably well fit by a partial covering fraction absorption model with a covering fraction of ~ 0.7. Models assuming simple galactic absorption are NOT consistent with the data. There is also evidence for an absorption feature at ~ 0.49 keV, consistent with the redshifted O K-edge one would expect from intrinsic absorption due to cold material. In addition, we have constructed a grid of detailed models for the expected X-ray spectra and surface brightnesses of cluster cooling flows including the opacity due to accumulated cold material. These models indicate that derived values for the total cooling rate dot M may be underestimated by ~ 2 assuming 100% of the cooling material goes into a cold, X-ray absorbing form. We find that models with higher mass deposition in the central regions can produce profiles comparable to the dot M(
Sarazin Craig L.
Wise Michael Wayne
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