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Social and Behavioral Sciences Commons

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University of Wollongong

2001

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Articles 1 - 3 of 3

Full-Text Articles in Social and Behavioral Sciences

On The Soft X-Ray Spectrum Of Cooling Flows, A C. Fabian, R F. Mushotzky, Paul E. J Nulsen, J R. Peterson Jan 2001

On The Soft X-Ray Spectrum Of Cooling Flows, A C. Fabian, R F. Mushotzky, Paul E. J Nulsen, J R. Peterson

Faculty of Engineering and Information Sciences - Papers: Part A

Strong evidence for cooling flows has been found in low-resolution X-ray imaging and spectra of many clusters of galaxies. However, high-resolution X-ray spectra of several clusters from the Reflection Grating Spectrometer on XMM-Newton now show a soft X-ray spectrum inconsistent with a simple cooling flow. The main problem is a lack of the emission lines expected from gas cooling below 1–2 keV. Lines from gas at about 2–3 keV are observed, even in a high-temperature cluster such as A1835, indicating that gas is cooling down to about 2–3 keV, but is not found at lower temperatures. Here ...


Chandra X-Ray Observations Of The 3c 295 Cluster Core, S W. Allen, G B. Taylor, Paul E J Nulsen, R M. Johnstone, L P. David, S Ettori, A C. Fabian, W R. Forman, C Jones, B Mcnamara Jan 2001

Chandra X-Ray Observations Of The 3c 295 Cluster Core, S W. Allen, G B. Taylor, Paul E J Nulsen, R M. Johnstone, L P. David, S Ettori, A C. Fabian, W R. Forman, C Jones, B Mcnamara

Faculty of Engineering and Information Sciences - Papers: Part A

We examine the properties of the X-ray gas in the central regions of the distant (z=0.46), X-ray luminous cluster of galaxies surrounding the powerful radio source 3C 295, using observations made with the Chandra Observatory. Between radii of 50 and 500 kpc, the cluster gas is approximately isothermal with an emission-weighted temperature, kT∼5 keV. Within the central 50-kpc radius this value drops to kT∼3.7 keV. The spectral and imaging Chandra data indicate the presence of a cooling flow within the central 50-kpc radius of the cluster, with a mass deposition rate of approximately 280 M ...


The Soft X-Ray Background: Evidence For Widespread Disruption Of The Gas Haloes Of Galaxy Groups, K K S Wu, A C. Fabian, Paul E. J Nulsen Jan 2001

The Soft X-Ray Background: Evidence For Widespread Disruption Of The Gas Haloes Of Galaxy Groups, K K S Wu, A C. Fabian, Paul E. J Nulsen

Faculty of Engineering and Information Sciences - Papers: Part A

Almost all of the extragalactic X-ray background (XRB) at 0.25 keV can be accounted for by radio-quiet quasars, allowing us to derive an upper limit of 4 keV cm−2 s−1 sr−1 keV−1 for the remaining background at 0.25 keV. However, the XRB from the gas haloes of groups of galaxies, with gas removal resulting from cooling accounted for, exceeds this upper limit by an order of magnitude if non-gravitational heating is not included. We calculate this using simulations of halo merger trees and realistic gas density profiles, which we require to reproduce the observed ...