Sloshing cold fronts in the IC1860 group .
Abstract
We present a combined X-ray, optical, and radio analysis of the galaxy group IC 1860 using the currently available Chandra and XMM data, literature multi-object spectroscopy data and GMRT data. The Chandra and XMM data reveal two surface brightness discontinuities at 45 and 76 kpc shown to be consistent with a pair of cold fronts. We find evidence of a characteristic spiral pattern in the X-ray gas distribution, tilted with respect to the plane of the sky, indicative of a mainly line-of-sight off-axis merger responsible for the sloshing. We identify the likely perturber as an optically disturbed spiral galaxy, IC 1859. The peculiar velocity of the BCG with respect to the mean group velocity is another signature consistent with the sloshing scenario. The GMRT observation at 325 MHz shows extended radio emission: one component is contained within the inner cold front as seen in some galaxy clusters, whereas the second component is detached and in the vicinity of the spiral feature. The limits obtained from the NVSS at 1.4 GHz point to a very steep spectral emission coming from aged radio plasma. The evidence presented in this study is among the strongest supporting the currently favored model of cold front formation in relaxed objects and establishes the group scale as a chief environment to study this phenomenon.
- Publication:
-
Memorie della Societa Astronomica Italiana
- Pub Date:
- 2013
- Bibcode:
- 2013MmSAI..84..743G
- Keywords:
-
- clusters: general;
- X-rays: galaxies: clusters;
- hydrodynamics;
- galaxies: kinematics and dynamics;
- galaxies: clusters: individual (IC 1860 group)