Intracluster patches of baryons in the core of the Fornax cluster

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>In the core of the Fornax cluster, on the west side of NGC 1399, we have detected a previously unknown region of intracluster light (ICL). It is made up by several faint (μ_r ≃ 28–29 mag arcsec⁻²) patches of diffuse light. The bulk of the ICL is located in between the three bright galaxies in the core, NGC 1387, NGC 1379, and NGC 1381, at 10 ⩽ <em>R</em> ⩽ 40 arcmin (~58–230 kpc) from the central galaxy NGC 1399. We show that the ICL is the counterpart in the diffuse light of the known over-density in the population of blue globular clusters (GCs). The total g-band luminosity of the ICL is <em>L_g</em> ≃ 8.3 × 10⁹ <em>L</em> ⊙, which is ~5% of the total luminosity of NGC 1399. This is consistent with the fraction of the blue GCs in the same region of the cluster. The ICL has <em>g − r</em> ∼ mag, which is similar to the colors in the halo of the bright galaxies in the cluster core. The new findings were compared with theoretical predictions for the ICL formation and they support a scenario in which the intracluster population detected in the core of the Fornax cluster is build up by the tidal stripping of material (stars and GCs) from galaxy outskirts in a close passage with the central brightest galaxy (cD). Moreover, the diffuse form of the ICL and its location close to the core of the cluster is expected in a dynamically evolved cluster like Fornax.</p></div>