Flow Patterns of Cluster Winds and X-Ray Emissions from Clusters of Galaxies

Abstract

751The flow of intracluster gas injected from galaxies by galactic winds or ram pressure 1s investigated by numerical time-dependent calculations in the beam scheme.Under a given gravitational field and mass loss rate, there are three flow patterns at the Hubble time, depending on the temperature of the injected gas. If we take a gravitational field of the Coma cluster, lower temperature of the injected gas than 10' OK and higher temperature than 3 X 10 8 OK result in wholly inward and wholly outward flow, respectively.For the temperature between them, there appears a partially inward and outward flow that the injected gas flows inwardly within a stagnation point and outwardly outside of it.The highest X-ray luminosity is expected for the case of the pure inflows, because of high central gas density. The pure outflows become steady at the Hubble time and result in the lowest luminosity in spite of higher central temperatures. The partial flows are the intermediate case. It is concluded that the results for the pure inflow or partial flow models are consistent with X-ray observational data of the Coma cluster. § I. IntroductionMany clusters of galaxies are known as powerful X-ray sources!) and models of X-ray emissions from these clusters have been proposed. There are two types of the models, that is, the thermal bremsstrahlung model and the inverse-Compton model. However, observations of X-ray spectra and of iron line emissions at 7 ke V from clusters 2 J.sJ seem to support the existence of a hot intracluster plasma with a temperature of 10 8 oK and favor the thermal bremsstrahlung model. The iron line emission also suggests that the hot plasma might be supplied not only from primordial matter left at the initial formation of galaxies but also from stars 111 galaxies where the nuclear synthesis proceeded.Gull and Northover 4 J and Lea 5 l studied static models of hot primordial matter.They and other authors 6 l computed the infall of the primordial gas or the intracluster gas distributed homogeneously. They, however, ignored the effect of the gas ejected from stars in galaxies into clusters.The theory of stellar evolution reveals that a part of stellar mass is shedded into galaxies when less massive stars evolve from the giant branch to the horizontal branch,') while observations directly show that mass loss from stars occurs as planetary nebula and supernova. It is also likely that the stellar winds from at Bibliothekssystem der Universitaet Giessen on May 14, 2015 http://ptp.oxfordjournals.org/ Downloaded from

Characteristics of the response of isothermal atmospheres with nonlinear waves

“…We have adopted a numerical code used by Hirayama et al (1978) with a suitable choice of the cell interval, which we have modified slightly so that gravity is included in the source term in the equation of momentum conservation.…”