On the Fe abundance peak formation in cool-core clusters of galaxies: hints from cluster WARPJ1415.1+3612 at z = 1.03

¹ INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Italy
e-mail: sabrina.degrandi@brera.inaf.it
² INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
e-mail: jsantos@arcetri.astro.it; ptozzi@arcetri.astro.it
³ INAF, Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34143 Trieste, Italy
e-mail: nonino@oats.inaf.it
⁴ INAF – IASF, via Bassini 15, 20100 Milano, Italy
e-mail: silvano@iasf-milano.inaf.it; afritz@iasf-milano.inaf.it
⁵ Università di Milano, 20100 Milano, Italy
e-mail: mariachiara.rossetti@unimi.it
⁶ Università di Ferrara, Via Saragat 1, 44122 Ferrara, Italy
e-mail: rosati@fe.infn.it

Received: 2 April 2014
Accepted: 30 May 2014

Abstract

We present a detailed study of the iron content of the core of the high-redshift cluster WARPJ1415.1+3612 (z = 1.03). By comparing the central Fe mass excess observed in this system, M_Fe^exc = (1.67 ± 0.40) × 10⁹ M_⊙, with those measured in local cool-core systems, we infer that the bulk of the mass excess was already in place at z = 1, when the age of the Universe was about half of what it is today. Our measures point to an early and intense period of star formation most likely associated with the formation of the BCG. Indeed, in the case of the power-law delay time distribution with slope − 1, which reproduces the data of WARPJ1415.1+3612 best, half of the supernovae explode within 0.4 Gyr of the formation of the BCG. Finally, while for local cool-core clusters the Fe distribution is broader than the near-infrared light distribution of the BCG, in WARPJ1415.1+3612 the two distributions are consistent, indicating that the process responsible for broadening the Fe distribution in local systems has not yet started in this distant cluster.