This effectively halts star formation in the galaxy, supporting the belief that ram pressure stripping could be one of the processes responsible for the morphology density relation.
The result of ram pressure stripping is a galaxy which contains very little cold gas. This has revealed bright blue stars along the leading edge of the galaxy (bottom of the galaxy in the image). Our results suggest that if there is any ram pressure stripping induced enhancement, it is at best locally modest, and galaxies undergoing enhancement make up a. At the same time, the ‘wind’ has pushed the dust and gas that would normally be found ahead of the motion of the galaxy up into the galaxy itself. Streamers of dust and gas can be seen trailing behind the motion of the galaxy, obscuring and reddening the stars behind (top of the galaxy in the image).This observation suggests that the loosely bound dust and gas in the outer regions of the disk has been stripped from the galaxy after the formation of these stars. The stellar disk (blue) appears to extend well beyond the star forming disk of dust and gas.This indicates that the galaxy is having trouble holding onto the loosely bound dust and gas in the outer regions of the disk against the pressure of the ‘wind’. The disk of dust and gas appears bowed.The different symbols correspond to the different inclination angles (triangles: 90o, diamonds. Negative values indicate that the galaxy falls into the cluster center. For example, NGC 4402 (right), which is currently falling into the Virgo cluster, shows several clear indicators that ram pressure stripping is at work: Critical distance at which the total enclosed mass within 20 kpc drops below 5×109 M (solid lines) and 3 × 109 M (dashed lines) as a function of the normalized ram pressure maximum for each simulation. ‘Ram pressure stripping’ occurs if this wind is strong enough to overcome the gravitational potential of the galaxy to remove the gas contained within it.Įvidence for ram pressure stripping can be found in many galaxy clusters. As individual galaxies move within such clusters, they experience this intra-cluster gas as a ‘wind’ – much like the wind experienced by a moving bicyclist, even on a still day.
Galaxy clusters are permeated by hot, X-ray emitting gas known as the intra-cluster medium. The density of the ambient medium decreases as we decrease the mass, suppressing the effect of ram pressure. Crowl (Yale University) and WIYN/NOAO/AURA/NSF We next describe ram pressure stripping in a group environment where the halo mass of the group is assumed to be 2 × 10 13.5 M. The bowed and truncated disk, and the concentration of dust and gas to one side of the galaxy are all indicators that ram pressure stripping is forcing gas out of the galaxy. The spiral galaxy, NGC4402, is currently falling towards the centre of the Virgo cluster (downwards in this image).
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