Fossil groups origins II. Unveiling the formation of the brightest group galaxies through their scaling relations

Abstract

(Abridged) Fossil systems are galaxy associations dominated by a relatively isolated, bright elliptical galaxy, surrounded by a group of smaller galaxies lacking L* objects. We analyzed the near-infrared photometric and structural properties of a sample of 20 BGGs present in FGs in order to better understand their formation mechanisms. Their surface-brightness distribution was fitted to a Sersic profile using the GASP2D algorithm. Then, the standard scaling relations were derived for the first time for these galaxies and compared with those of normal ellipticals and brightest cluster galaxies in non-fossil systems. The BGGs presented in this study represent a subset of the most massive galaxies in the Universe. We found that their ellipticity profiles are continuously increasing with the galactocentric radius. Our fossil BCGs follow closely the fundamental plane described by normal ellipticals. However, they depart from both the log σ_0 vs. log L_{K_{s}} and log r_{\rm e} vs. log L_{K_{s}} relations described by intermediate mass ellipticals. This occurs in the sense that our BGGs have larger effective radii and smaller velocity dispersions than those predicted by these relations. We also found that more elliptical galaxies systematically deviate from the previous relations while more rounder object do not. No similar correlation was found with the Sersic index. The derived scaling relations can be interpreted in terms of the formation scenario of the BGGs. Because our BGGs follow the fundamental plane tilt but they have larger effective radii than expected for intermediate mass ellipticals, we suggest that they only went through dissipational mergers in a early stage of their evolution and then assembled the bulk of their mass through subsequent dry mergers, contrary to previous claims that BGGs in FGs were formed mainly by the merging of gas-rich galaxies.

16 pages, 10 figures, accepted for publication at A&A

References in corpus (18)

• The influence of gas on the structure of merger remnants
• Dissipation and Extra Light in Galactic Nuclei: II. 'Cusp' Ellipticals
• Intracluster light and the extended stellar envelopes of cD galaxies: An analytical description
• Scaling relations in fossil galaxy groups
• The Mass Assembly of Fossil Groups of Galaxies in the Millennium Simulation
• Dissipation and the Fundamental Plane: Observational Tests
• The Fossil Phase in the Life of a Galaxy Group
• Photometric Properties and Scaling Relations of Early Type Brightest Cluster Galaxies
• Are disk galaxies the progenitors of giant ellipticals?
• Fossil Groups in the Sloan Digital Sky Survey
• The evolution of the galaxy Red Sequence in simulated clusters and groups
• Stellar Populations of Bulges in 14 Cluster Disc Galaxies
• A fossil galaxy cluster; an X-ray and optical study of RX J1416.4+2315
• Velocity dispersion, mass and the luminosity function of the fossil cluster RX J1416.4+2315
• On the Nature of Fossil Galaxy Groups: Are they really fossils ?
• Structure and dynamics of galaxies with a low surface brightness disc. I. The stellar and ionised-gas kinematics
• The Kormendy Relation for early-type galaxies. Dependence on the magnitude range
• Are fossil groups a challenge of the Cold Dark Matter paradigm?

Cited by in corpus (28)

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• Brightest Group Galaxies: Stellar Mass and Star Formation Rate (paper I)
• The intrinsic shape of bulges in the CALIFA survey
• Fossil groups in the Millennium simulation. From the brightest to the faintest galaxies during the past 8 Gyr
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• Chandra Studies of the X-ray Gas Properties of Fossil Systems
• RXCJ1111.6+4050 galaxy cluster: the observational evidence of a transitional fossil group