Isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metalicity gradients

Abstract

The chemodynamical evolution of spherical multi-component self-gravitating models for isolated dwarf galaxies is studied. We compared their evolution with and without feedback effects from star formation processes. We found that initially cuspy dark matter profiles flatten with time without any special tuning conditions as a result of star formation. Thus the seemingly flattened profiles found in many dwarfs do not contradict the cuspy profiles predicted by cosmological models. We also calculated the chemical evolution of stars and gas, to permit comparisons with observational data.

Dissipative phenomena in extended-body interactions

“…These results nevertheless contrast with observational properties, as pointed out in Steinmetz & Navarro (1999), Navarro & Steinmetz (2000a), Navarro & Steinmetz (2000b), Portinari & Sommer-Larsen (2007) suggesting that numerical recipes can be improved, as recently shown by Pasetto et al (2010) using prescriptions based on chemo-dynamical studies. These authors made it clear that gas survival in spherical dwarf galaxies is perfectly compatible with the expected SNe rate over the whole mass range of interest for dwarf galaxies (see their Table 1).…”

“…These authors made it clear that gas survival in spherical dwarf galaxies is perfectly compatible with the expected SNe rate over the whole mass range of interest for dwarf galaxies (see their Table 1). This reasonably stems from the reduced SNe feedback expected in the local environment (Cioffi & Shull 1991) different from dwarf to spiral galaxies (Bradamante et al 1998), and it explains the co-existence of old stellar populations and a reservoir of neutral gas in a natural way (e.g., Phillipps et al 1990;Pasetto et al 2010). …”

“…The technique that we adopted is based on a chemodynamical code (e.g., Berczik et al 2003) with new star formation recipes described in detail in Pasetto et al (2010). Our simulations reach a mass resolution of 118 M , resolving the core of the dwarf galaxy with about 127000 particles (stars) over about 700 000 total particles.…”

Orbital evolution of the Carina dwarf galaxy and self-consistent determination of star formation history

“…While the external density profile is generally attributed to the tidal interactions, it is unclear whether the inner regions of dSphs are strongly influenced by tides, or whether a high M/L ratio can dampen the tidal gravitational shocks (see Burkert 1997;Kroupa 1997;Gómez-Flechoso et al 1999;Klessen & Zhao 2002;Gómez-Flechoso & Martínez-Delgado 2003;Kleyna et al 2002;Walker et al 2006a,b;Gilmore et al 2007) 1 . The radial velocity dispersion profile is a powerful tool for investigating multi-component self-gravitating systems, since it is sensitive to the dark matter distribution and accessible to observations (e.g., Pasetto et al 2010). Recently, radial velocity data have become available to track the line-of-sight velocity dispersion as a function of radius for many LG dwarf galaxies (e.g., Pasetto et al 2010;Tolstoy et al 2004;Westfall et al 2006;Wilkinson et al 2004;Muñoz et al 2005;Walker et al 2006aWalker et al ,b, 2009Sohn et al 2007; Koch et al 2007c,b;Muñoz et al 2006), and these data A&A 525, A99 (2011) permit more detailed modelling of the dwarf galaxies kinematic status (e.g., Kroupa 1997;Kleyna et al 1999;Kazantzidis et al 2004;Read et al 2006;Peñarrubia et al 2008Peñarrubia et al , 2009Pasetto et al 2010).…”

“…The radial velocity dispersion profile is a powerful tool for investigating multi-component self-gravitating systems, since it is sensitive to the dark matter distribution and accessible to observations (e.g., Pasetto et al 2010). Recently, radial velocity data have become available to track the line-of-sight velocity dispersion as a function of radius for many LG dwarf galaxies (e.g., Pasetto et al 2010;Tolstoy et al 2004;Westfall et al 2006;Wilkinson et al 2004;Muñoz et al 2005;Walker et al 2006aWalker et al ,b, 2009Sohn et al 2007; Koch et al 2007c,b;Muñoz et al 2006), and these data A&A 525, A99 (2011) permit more detailed modelling of the dwarf galaxies kinematic status (e.g., Kroupa 1997;Kleyna et al 1999;Kazantzidis et al 2004;Read et al 2006;Peñarrubia et al 2008Peñarrubia et al , 2009Pasetto et al 2010). For the same approach to multi-component dSphs in the cosmological ΛCMD contest see, Stoehr et al (2002) and Hayashi et al (2003) or, in a purely dynamical collisonless regime see Ciotti & Morganti (2009), where the primordial stellar population is embedded in an extended dark matter halo without considering any gas process.…”