Gone with the wind: The origin of SO galaxies in clusters

Science

Volumn 288, Issue 5471, 2000, Pages 1617-1620

  Quilis, Vicent ^a   Moore, Ben ^a   Bower, Richard ^a  

^a DURHAM UNIVERSITY   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

HYDROGEN;

ARTICLE; ASTRONOMY; COSMOS; DIFFUSION; EVOLUTION; HYDRODYNAMICS; PRESSURE; PRIORITY JOURNAL;

EID: 0034596049     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.288.5471.1617     Document Type: Article

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19. V. Quilis, J. Ma. Ibánez, D. Sáez, Astrophys. J. 469, 11 (1996). The numerical code used in this report is a 3D Eulerian code on a fix cartesian grid. This code is based on modern high-resolution shock-capturing (HRSC) techniques, a general denomination for a recently developed family of methods to solve hyperbolic systems of equations such as the hydrodynamic equations. Our code is similar to PPM (piecewise parabolic method) but with some particular features. It has four key ingredients: (i) conservative formulation, numerical quantities are conserved up to the numerical order of the method, (ii) the reconstruction procedure, which allow to recover the distribution of the quantities inside the computational cells, (iii) the Riemann solver, which solves the evolution of discontinuities between cell interfaces, and (iv) the advancing in time, designed to be consistent with the conservation properties. HRSC schemes have the following advantages: (i) they do not suffer from numerical artifacts such as artificial viscosity, (ii) they can resolve strong shocks extremely well, typically in one or two cells, (iii) strong gradients are perfectly modeled, and (iv) they work very well in low-density regions and are high-order in smooth regions of the flow.
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37. 7 years, then the decline in the molecular gas content of infalling galaxies is as rapid as the rate of HI removal by the stripping process. Initially, this seems at odds with the observations of J. D. P. Kenney and J. S. Young [Astrophys. J. 344, 171 (1989)], who found that bright HI-deficient spirals in the Virgo cluster contained similar masses of molecular H to counterparts of the same morphological type in the field. This apparently suggests that molecular clouds must have a lifetime that is considerably longer than the stripping time scale. However, we note that this comparison is made at a fixed morphology. Morphology is strongly dependent on the star formation rate, in the sense that galaxies with low star formation rate will be classified as earlier type. Thus, it is unlikely that galaxies with similar morphology will exhibit large differences in CO content. Rather, a large deficiency in CO will result in a galaxy with low star formation rate and earlier morphological type. It is then hard to disentangle any deficiency in CO content due to stripping from the reduction in CO content expected for the change in morphological type. It is encouraging, nevertheless, that galaxies of earlier type match more closely the curve in Kenney and Young's data expected if the molecular and atomic gas contents decline at similar rates.
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41. Supplementary material is available at www. sciencemag.org/feature/data/1050370.shl.
42. V.Q. is a Marie Curie research fellow of the European Union (grant HPMF-CT-1999-00052). During the first part of this work, V.Q. was supported by a fellowship of the Spanish SEUID (Ministerio de Educación y Cultura) and partially by Spanish DGES (grant PB96-0797). B.M. is a Royal Society research fellow. Numerical simulations were carried out as part of the Virgo Consortium and the UK Computational Cosmology Consortium.