The generation of optical emission-line filaments in galaxy clusters

Abstract

Recent data support the idea that the filaments observed in H_alpha emission near the centres of some galaxy clusters were shaped by bulk flows within their intracluster media. We present numerical simulations of evaporated clump material interacting with impinging winds to investigate this possibility. In each simulation, a clump falls due to gravity while the drag of a wind retards the fall of evaporated material leading to elongation of the tail. However, we find that long filaments can only form if the outflowing wind velocity is sufficiently large, 10^8 cm s^-1. Otherwise, the tail material sinks almost as quickly as the cloud. For reasonable values of parameters, the morphological structure of a tail is qualitatively similar to those observed in clusters. Under certain conditions, the kinematics of the tail resemble those reported in Hatch et al.(2006). A comparison of the observations with the numerical results indicates that the filaments are likely to be a few tens of Myrs old. We also present arguments which suggest that the momentum transfer, from an outflowing wind, in the formation of these filaments is probably significant. As a result, tail formation could play a role in dissipating some of the energy injected by a central AGN close to the cluster centre where it is needed most. The trapping of energy by the cold gas may provide an additional feedback mechanism that helps to regulate the heating of the central regions of galaxy clusters and couple the AGN to the ICM.

arXiv comment15 pages, 18 figures. Altered density values in table 1, which were a factor of 1000 too small. Also extended caption for table 1 to show the mass outflow rate. Accepted for publication in MNRAS

References in corpus (16)

• The ROSAT Brightest Cluster Sample (BCS): -- III. Optical spectra of the central cluster galaxies
• The detection of molecular gas in the central galaxies of cooling-flow clusters
• Filaments, Bubbles, and Weak Shocks in the Gaseous Atmosphere of M87
• The relationship between the optical Halpha filaments and the X-ray emission in the core of the Perseus cluster
• A deeper X-ray study of the core of the Perseus galaxy cluster: the power of sound waves and the distribution of metals and cosmic rays
• AGN Feedback and Cooling Flows: Problems with Simple Hydrodynamical Models
• Impact of tangled magnetic fields on AGN-blown bubbles
• HST Observations of Vibrationally-Excited Molecular Hydrogen in Cluster Cooling Flow Nebulae
• On the origin and excitation of the extended nebula surrounding NGC 1275
• Ionized nebulae surrounding brightest cluster galaxies
• Metal mixing by buoyant bubbles in galaxy clusters
• Dynamical and Pressure Structures in Winds with Multiple Embedded Evaporating Clumps I. 2D Numerical Simulations
• Cold filaments in galaxy clusters: effects of heat conduction
• Energy Dissipation in Multi-Phase Infalling Clouds in Galaxy Halos
• Heating Rate Profiles in Galaxy Clusters
• The tails in the Helix Nebula NGC 7293

Cited by in corpus (7)

• Evolution of shocks and turbulence in major cluster mergers
• The X-ray cavities, filaments and cold fronts in the core of the galaxy group NGC 5044
• The turbulent destruction of clouds - I. A k-epsilon treatment of turbulence in 2D models of adiabatic shock-cloud interactions
• Adaptively refined large eddy simulations of clusters
• The Turbulent Destruction of Clouds - II. Mach Number Dependence, Mass-loss Rates, and Tail Formation
• Molecular Tracers of Filamentary CO Emission Regions Surrounding the Central Galaxies of Clusters
• Cold gas in the Intra Cluster Medium: implications for flow dynamics and powering optical nebulae