Galaxy evolution in the Virgo clusterBernd VollmerCDS, Observatoire de Strasbourg

Interaction of a spiral galaxy with its environmentGravitational interaction galaxy - cluster

Gravitational interaction galaxy - galaxy

Ram pressure galaxy ISM intracluster medium (ICM)(Kenney et al. 1995)(Bhringer et al. 1994)(Kenney et al. 2004)

Interaction diagnostics for Virgo cluster spiral galaxiesObservations: HI (VLA, Effelsberg), CO(1-0) (IRAM 30m), radio continuum (VLA)Simulations: non-collisional and collisional N-body code (sticky particles) including ram pressureComparison of the gas distribution and velocity field

The Virgo Cluster3 MpcNGC4522(Cayatte et al. 1990)

Observational gas characteristicsExtraplanar, high surface brightness gas (NGC 4522, NGC 4438)Extraplanar, very low surface brightness gas (NGC 4388)Perturbed, low surface brightness arms (NGC 4548, NGC 4569, NGC 4654, NGC 4254)

3 MpcNGC4522(Cayatte et al. 1990)

NGC 4522Contours: PIGreyscale: HI (Kenney et al. 2004)Contours: PI (Vollmer et al. 2004)Greyscale: B band(nearly edge-on disk)

NGC 4522Observations ModelGrey: HI Contours: 6cm PI Grey: gas Contours: stellar disk

3 MpcNGC4522(Cayatte et al. 1990)

NGC 4438Color: optical B bandSpectra: IRAM 30m CO(1-0) (Kenney et al. 1995) (Vollmer et al. 2004)

NGC 4438ModelGrey: gas Contours: starsModelspectraCO(1-0)spectra

Observational gas characteristicsExtraplanar, high surface brightness gas (NGC 4522, NGC 4438)Extraplanar, very low surface brightness gas (NGC 4388)Perturbed, low surface brightness arms (NGC 4548, NGC 4569, NGC 4654, NGC 4254)

3 MpcNGC4522(Cayatte et al. 1990)

NGC 438820 kpc

NGC 4388modelobservations(Vollmer & Huchtmeier 2003)

Observational gas characteristicsExtraplanar, high surface brightness gas (NGC 4522, NGC 4438)Extraplanar, very low surface brightness gas (NGC 4388)Perturbed, low surface brightness arms (NGC 4548, NGC 4569, NGC 4654, NGC 4254)

3 MpcNGC4522(Cayatte et al. 1990)

NGC 4548Grey: HIContours: CO(1-0)(Vollmer et al. 1999)3D visualization

3 MpcNGC4522(Cayatte et al. 1990)

NGC 4569Contours: HI VLA C+DGreyscale: B band(Vollmer et al. 2004)

NGC 4569HI observations active stripping past stripping (Vollmer et al. 2004)

3 MpcNGC4522(Cayatte et al. 1990)

NGC 4654(Phookun & Mundy 1995)HI gas distributionHI velocity fieldNGC4654NGC4639

NGC 4654model I:ram pressuremodel II:ram pressure +tidal interactionHI observations(Phookun & Mundy 1995)(Vollmer 2003)gas distribution velocity field

3 MpcNGC4522(Cayatte et al. 1990)

NGC 4254Model:gravitationalonly

Model:gravitational+ ram pressure+ evaporation/ expansion

HI observations(Phookun et al. 1993)Solid: model spectraDashed: Effelsberg HI spectra(Vollmer 2004)

Towards a time sequence of ram pressure strippingNGC 4438 NGC 4569NGC 4522 NGC 4548NGC 4388modelmodelmodelmodel

NGC4654NGC4522NGC4254(3cm, Effelsberg 100m) (Chyzy et al.)(6cm, VLA)(Vollmer et al.)(3.6cm, VLA)(Chyzy et al.)Grey: model gas distributionContours: Model distributionof polarised radiocontinuum emissionEvolution of the polarised radio continuum emission(Otmianowska-Mazur & Vollmer 2003)

Polarized radio emission in NGC4654 simulations versus observations Observations SimulationsEffelsberg 3cm :Chyzy et al. in prep.)(Soida et al. in prep.)