On the metal abundance in the core of M 87

¹ Istituto di Fisica Cosmica, CNR, via Bassini 15, 20133 Milano, Italy
² Università di Milano Bicocca, Dip. di Fisica, P.za della Scienza 3 20133 Milano, Italy

Corresponding author: S. Molendi, silvano@ifctr.mi.cnr.it

Received: 11 May 2001
Accepted: 19 June 2001

Abstract

We revisit the XMM-Newton observation of M 87 to make a new and more detailed measurement of the metal abundance profile. After having verified that spectral fits with single temperature models show a dramatic abundance drop within 1 arcmin of the cluster core, we show that more appropriate models, which include a multi-temperature component to account for the strong temperature gradient observed in M 87, and a power-law component to account for the emission of the nucleus and knot A, give a substantially flat abundance profile. The drastic abundance decrement found by fitting a single temperature component to the data is an artifact known as "Fe-bias" (Buote [CITE]a,b) following from the application of an oversimplified spectral model to the data.