Early-type dwarf galaxies with multicomponent stellar structure: Are they remnants of disc galaxies strongly transformed by their environment?

Abstract

Context. The surface brightness distribution of ∼30-40% of the early-type dwarf galaxies with −18 ≤ M B ≤ −15 in the Virgo and the Coma clusters is fitted by models that include two structural components (Sérsic + exponential) as for bright disc galaxies. Aims. The goal of the present study is to determine whether early-type dwarf galaxies with a two-component stellar structure in the Virgo and the Coma clusters are low-luminosity copies of bright disc galaxies or are the remnants of bright galaxies strongly transformed by cluster environmental effects. Methods. I analysed the location of bright disc galaxies and early-type dwarfs in the r b,e /h-n plane. The location in this plane of the two-component dwarf galaxies was compared with the remnants of tidally disrupted disc galaxies reported by numerical simulations. Results. Bright unbarred disc galaxies show a strong correlation in the r b,e /h-n plane. Galaxies with larger Sérsic shape parameters show a higher r b,e /h ratio. In contrast, two-component early-type dwarf galaxies do not follow the same correlation. A fraction (∼55%) of them are located outside the locus defined in this plane by having 95% of bright disc galaxies. This distribution indicates that they are not a low-mass replica of bright disc galaxies. The different location in the r b,e /h-n plane of two-component early-type dwarfs and bright galaxies can be qualitatively explain whether the former are remnants of disc galaxies strongly transformed by tidal processes. Conclusions. The progenitors of ∼20−25% of early-type dwarf galaxies with −18 ≤ M B ≤ −15 in the Virgo and Coma clusters could be bright disc galaxies transformed by effects of the environment. These tidally transformed galaxies can be selected according to their location in the r b,e /h-n plane.

Fossil group origins

“…There is some dynamical evidence that at least a fraction of dwarf galaxies residing in galaxy clusters today were not formed within the cluster (e.g., Conselice et al 2001). In contrast, they were accreted into the clusters over several Gyr (Adami et al 2007;Aguerri et al 2017), or could be produced by the disruption of brighter galaxies due to strong tidal interactions between galaxies or with the cluster potential (e.g., Popesso et al 2006;Aguerri 2016).…”

“…The lack of dwarfs shown by this group can also be explained as a consequence of a destruction of low-mass halos in this system. This galaxy disruption could be due to interactions with the group potential or other galaxy group members (e.g., Popesso et al 2006;Aguerri 2016). The low velocity dispersion of the system would favor low-velocity interactions that make stripping of stars from low-mass galaxies more efficient, making them fainter (e.g., Mastropietro et al 2005;Aguerri & González-García 2009;D'Onghia et al 2009D'Onghia et al , 2010.…”

Implications for the Origin of Early-type Dwarf Galaxies: A Detailed Look at the Isolated Rotating Early-type Dwarf Galaxy LEDA 2108986 (CG 611), Ramifications for the Fundamental Plane’s Kinematic Scaling, and the Spin–Ellipticity Diagram

“…They found that less than onequarter of orbits from a cosmological simulation resulted in any stripping of disk stars, as required in the harassment scenario. In addition, Aguerri (2016) concluded, based on his analysis of the (R e,bulge /h disk )-n diagram, that most dwarf ETGs in clusters are not transformed disk galaxies.…”

The Fornax Deep Survey with the VST

“…Clusters of galaxies are excellent sites to study the effects of the environment on the galaxy structure and on the star formation rate (e.g. Trujillo et al 2001;Lewis et al 2002;Aguerri et al 2004;Gutiérrez et al 2004;Méndez-Abreu et al 2012;Aguerri 2016;Merluzzi et al 2016;Lisker et al 2018). There are several types of environmental mechanisms that can act, also simultaneously, on the cluster members, which induce strong changes in the stellar distribution and gas content.…”