SearcharxivSearch

arXiv subjects

Thomas Toniazzo

Publications and source records attributed to Thomas Toniazzo.

2 recordsLinked to original sources

Gas Dynamic Stripping and X-Ray Emission of Cluster Elliptical Galaxies

Detailed 3-D numerical simulations of an elliptical galaxy orbiting in a gas-rich cluster of galaxies indicate that gas dynamic stripping is less efficient than the results from previous, simpler calculations (Takeda et al. 1984; Gaetz et al. 1987) implied. This result is consistent with X-ray data for cluster elliptical galaxies. Hydrodynamic torques and direct accretion of orbital angular momentum can result in the formation of a cold gaseous disk, even in a non-rotating galaxy. The gas lost by cluster galaxies via the process of gas dynamic stripping tends to produce a colder, chemically enriched cluster gas core. A comparison of the models with the available X-ray data of cluster galaxies shows that the X-ray luminosity distribution of cluster galaxies may reflect hydrodynamic stripping, but also that a purely hydrodynamic treatment is inadequate for the cooler interstellar medium near the centre of the galaxy.

astro-ph

COOLING FLOW MODELS OF THE X--RAY EMISSION AND TEMPERATURE PROFILES FOR A SAMPLE OF ELLIPTICAL GALAXIES

A simple spherically-symmetric, steady-state, cooling-flow description with gas loss (following Sarazin \& Ashe 1989), within galaxy models constrained by radially extended stellar dynamical data, is shown to provide generally reasonable fits to the existing data on X-ray emission profiles and temperatures for a set of bright elliptical galaxies in Virgo and Fornax. Three free parameters are needed to specify the model: the external mass flux, the external pressure, and a dimensionless factor, which regulates the mass deposition rate along the flow. Three different assumptions on the supernova rate have been considered. A moderate value for the supernova rate in elliptical galaxies is found to be preferred. Confining pressures of $p_{ext}\sim4\div15\times10^3\kelvin$ cm$^{-3}$ and significant accretion rates of external material, up to $4\msolar/\yr$, are suggested by our models. A possible correlation between $L_X/L_B$ and the iron abundance in the gas inside ellipticals is pointed out.

astro-ph