Temperature and total mass profiles of the A3571 cluster of galaxies

Abstract

We present BeppoSAX results of a spatially resolved spectral analysis of A3571, a relaxed nearby cluster of galaxies. In the central 2′ (130 h50-1 kpc) radius the metal abundance is 0.49 ± 0.08 solar and the absorption (1.13 ± 0.28) 1021 atom cm-2, whereas elsewhere within an 8′ (520 h50-1 kpc) radius the abundance is 0.32 ± 0.05 solar and the absorption consistent with the galactic value of 4.4 1020 atom cm-2. The significant central metal abundance enhancement is consistent with the supernova enrichment scenario. The excess absorption may be attributed to the cooling flow, whose mass flow rate is 80 ± 40 M⊙ yr-1 from our spectral fit. The BeppoSAX and ASCA radial temperature profiles agree over the entire overlapping radial range r < 25′ = 1.6 h50-1 Mpc. The combined BeppoSAX and ASCA temperature profile exhibits a constant value out to a radius of ∼10′ (650 h50-1 kpc) and a significant decrease (T ∝ r-0.55, corresponding to γ = 1.28) at larger radii. These temperature data are used to derive the total mass profile. The best fit NFW dark matter density model results in a temperature profile that is not convectively stable, but the model is acceptable within the uncertainties of the data. The temperature profile is acceptably modeled with a "core" model for the dark matter density, consisting of a core radius with a constant slope at larger radii. With this model the total mass and formal 90% confidence errors within the virial radius r178 (2.5 h50-1 Mpc) are 9.1-1.5+3.6 1014 h50-1 M⊙, by a factor of 1.4 smaller than the isothermal value. The gas mass fraction increases with radius, reaching fgas(r178) = 0.26-0.10+0.05 × h50-3/2. Assuming that the measured gas mass fraction is the lower limit to the primordial baryonic fraction gives Ωm < 0.4 at 90% confidence.