Intracluster Patches of Baryons in the Core of the Fornax Cluster

Abstract

In the core of the Fornax cluster, on the West side of NGC 1399, we have detected a previously unknown region of intra-cluster 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 ≤ R ≤ 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 L g 8.3 × 10 9 L , 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 g − r ∼ 0.7 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 intra-cluster 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 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 as Fornax.

Chandra Detection of Intracluster X-Ray Sources in Fornax

“…As a related remark, some GCs (and any associated GC-LMXBs) might also be classified as part of the ICL. Indeed, Iodice et al (2017) found the aforementioned ICL to be spatially coincident with a previously known overdensity of blue GCs (D'Abrusco et al 2016).…”

“…The third possibility is X-ray binaries associated with a more diffuse stellar population, either the extended stellar halo of NGC 1399 (Iodice et al 2016) or the ICL (Iodice et al 2017). The BCG halo grows primarily from mergers of infalling galaxies, whereas the ICL is built up mainly through stars tidally stripped from the outskirts of large galaxies or tidally disrupted low-mass galaxies orbiting in the cluster potential.…”

The Fornax 3D project: Unveiling the thick disk origin in FCC 170; possible signs of accretion

“…In addition, this light was shown to be the counterpart of previously detected over-densities of blue globular clusters (Bassino et al 2006;D'Abrusco et al 2016), indicators of a tidal stream. The morphology, the location and the faintness of this ICL were interpreted by Iodice et al (2017a) as signs of tidal stripping from the galaxies in this dense region, which would have passed close to the central cD in an earlier epoch. The velocity difference of FCC 170 with respect to NGC 1399 is compatible with tidal interactions with the cluster potential (Iodice et al 2017a), which could have strongly affected its evolution.…”

The Fornax3D project: Tracing the assembly history of the cluster from the kinematic and line-strength maps

“…The deep FDS imaging revealed that the region of the cluster where the clump is located hosts the bulk of the gravitational interactions between galaxies. It is the only region inside the virial radius where intra-cluster baryons were found, including faint stellar filaments between some of the galaxies (Iodice et al 2016(Iodice et al , 2017.…”