view Abstract Citations (12) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Characteristic-based Models for the Evolution of Cooling Flows Murray, Stephen D. ; Balbus, Steven A. Abstract X-ray observations over the past several years have established the existence of large amounts of hot gas within clusters of galaxies. In many cases, the cooling time of the gas is less than a Hubble time, implying that the gas must be flowing inward as a cooling flow, with inferred mass accretion rates exceeding 100 M_sun_ yr^-1^ in some cases. The fate of the cooling gas is uncertain. The observations that M decreases inward have generally been taken to imply that gas is "dropping out" of the flow to form stars. We examine this picture using numerical models of cooling flows. A basic premise of the models is that cluster ages are not much greater than their initial central cooling times. The models are made as simple as possible in order to best determine the roles played by thermal and dynamical processes as the flows evolve in time. Most important, we assume that mass is conserved. Unlike previous studies, the numerical method uses the theory of characteristics, which has several practical and conceptual advantages over standard finite difference techniques. It is found that the techniques to observationally obtain values of M are valid, despite the fact that they assume the flows to be in steady state, which the models find not to be the case. This is because the conservative energy equation used in the data reduction is highly insensitive to non-steady state effects. The lack of steady state evolution stems from the fact that the system evolves on the cooling time scale, which is a decreasing function of time. Observations of M increasing with r need not, therefore, directly imply mass dropout from the flow, but may also result from dynamical evolution. Because of the acceleration of the evolution with time, the total accreted mass is much smaller than would be inferred from the final value of the accretion rate, such that only ~10^11^ M_sun_ accrete within the inner 50 kpc. In other models, it is found that neither having a cluster potential which deepens with time, nor adding a central galactic potential delay the onset of core collapse, but, if anything, accelerate the evolution. Publication: The Astrophysical Journal Pub Date: August 1992 DOI: 10.1086/171633 Bibcode: 1992ApJ...395...99M Keywords: Astronomical Models; Cooling Flows (Astrophysics); Galactic Clusters; Intergalactic Media; X Ray Sources; High Temperature Gases; Hubble Constant; X Ray Astronomy; Astrophysics; GALAXIES: COOLING FLOWS; GALAXIES: CLUSTERING; GALAXIES: INTERGALACTIC MEDIUM; X-RAYS: GALAXIES full text sources ADS |