The XMM–NEWTON Project: I. The X-ray Luminosity – Temperature Relation at z > 0.4

Romer, A.K., Lumb, D. H., Bartlett, J.G., Blanchard, A., Burke, D.J., Collins, C.A., Nichol, R.C., Giard, M., Marty, P.B., Nevalainen, J., Sadat, R. and Vauclair, S. C. (2004) The XMM–NEWTON Project: I. The X-ray Luminosity – Temperature Relation at z > 0.4. Astronomy and Astrophysics, 420. pp. 853-872. ISSN 0066-4146

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We describe XMM-Newton Guaranteed Time observations of a sample of eight high redshift (0.45<z<0.62) clusters. The goal of these observations was to measure the luminosity and the temperature of the clusters to a precision of ∼10%, leading to constraints on the possible evolution of the luminosity–temperature (Lx − Tx) relation, and ultimately on the values of the matter density, M, and, to a lesser extent, the cosmological constant . The clusters were drawn from the SHARC and 160 Square Degree (160SD) ROSAT surveys and span a bolometric (0.0–20 keV) luminosity range of 2.0 to 14.4 ×1044 erg s−1 (Ho=50, M=1, =0). Here we describe our data analysis techniques and present, for the first time with XMMNewton, a Lx − Tx relation. For each of the eight clusters in the sample, we have measured total (r < rvirial) bolometric luminosities, performed -model fits to the radial surface profiles and made spectral fits to a single temperature isothermal model. We describe data analysis techniques that pay particular attention to background mitigation. We have also estimated temperatures and luminosities for two known clusters (Abell 2246 and RXJ1325.0-3814), and one new high redshift cluster candidate (XMMU J084701.8+345117), that were detected off-axis. Characterizing the Lx − Tx relation as Lx = L6( T 6keV ), we find L6 = 15.9+7.6 −5.2 × 1044erg s−1 and =2.7±0.4 for an = 0.0, M = 1.0, H0 = 50 km s−1 Mpc−1 cosmology at a typical redshift z ∼ 0.55. Comparing with the low redshift study by Markevitch, 1998, we find to be in agreement, and assuming Lx − Tx to evolve as (1 + z)A, we find A=0.68±0.26 for the same cosmology and A = 1.52+0.26 −0.27 for an = 0.7, M = 0.3 cosmology. Our A values are very similar to those found previously by Vikhlinin et al., 2002 using a compilation of Chandra observations of 0.39 < z < 1.26 clusters. We conclude that there is now evidence from both XMM-Newton and Chandra for an evolutionary trend in the Lx − Tx relation. This evolution is significantly below the level expected from the predictions of the self-similar model for an = 0.0, M = 1.0, cosmology, but consistent with self-similar model in an = 0.7, M = 0.3 cosmology. Our observations lend support to the robustness and completeness of the SHARC and 160SD surveys.

Item Type: Article
Keywords: X-rays: Galaxies: clusters
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QC Physics
Depositing User: Gemma Farrell
Date Deposited: 14 Mar 2008
Last Modified: 06 Mar 2017 14:12
Google Scholar:69 Citations

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