Temperature and total mass profiles of the A3571 cluster of galaxies

¹ Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
² SRON Laboratory for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
³ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street Cambridge, MA 02138, USA
⁴ Osservatorio Astronomico di Roma, via dell'Osservatorio 2, 00040 Monteporzio, Italy

Corresponding author: J. Nevalainen, jnevalai@astro.estec.esa.nl

Received: 1 November 2000
Accepted: 12 January 2001

Abstract

We present BeppoSAX results of a spatially resolved spectral analysis of A3571, a relaxed nearby cluster of galaxies. In the central 2´ (130 kpc) radius the metal abundance is solar and the absorption atom cm^-2, whereas elsewhere within an 8´ (520 kpc) radius the abundance is 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 yr^-1 from our spectral fit. The BeppoSAX and ASCA radial temperature profiles agree over the entire overlapping radial range 25´= 1.6 Mpc. The combined BeppoSAX and ASCA temperature profile exhibits a constant value out to a radius of ~10´(650 kpc) and a significant decrease (, corresponding to ) 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 Mpc) are , by a factor of 1.4 smaller than the isothermal value. The gas mass fraction increases with radius, reaching . Assuming that the measured gas mass fraction is the lower limit to the primordial baryonic fraction gives at 90% confidence.