Galaxy evolution in the Virgo Cluster - Home | Max Planck ... · NGC 4330 NGC 4522 NGC 4388 NGC...

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Galaxy evolution in the Virgo Cluster Bernd Vollmer CDS, Observatoire de Strasbourg

Transcript of Galaxy evolution in the Virgo Cluster - Home | Max Planck ... · NGC 4330 NGC 4522 NGC 4388 NGC...

Page 1: Galaxy evolution in the Virgo Cluster - Home | Max Planck ... · NGC 4330 NGC 4522 NGC 4388 NGC 4569 model model model model pre-peak near peak ~150Myr after peak ~300Myr after peak

Galaxy evolution in the VirgoCluster

Bernd VollmerCDS, Observatoire de Strasbourg

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Tout d’abord: un grand merci à

P. Amram, C. Balkowski, R. Beck, D. Bomans,A. Boselli, J. Braine, V. Cayatte, F. Combes, A. Chung, K. Chyzy, H. Crowl, W. Duschl, O. Garrido, W. Huchtmeier, J. Kenney, M. Marcelin, K. Otmianowska-Mazur, W. Reich, Y. Sofue, M. Soida, M. Urbanik, W. van Driel, J. van Gorkom, R. Wielebinski

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Galaxy evolution in the VirgoCluster

• Introduction• Interactions of a cluster spiral with its environment• The data• The model• NGC 4522 – a case study• Ram pressure stripping time sequence• Stripping of multiple gas phases• Ram pressure stripping and star formation• New VLA radio continuum observations

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Galaxy evolution

SDSSBlanton & Moustakas(2009)

starformationhistory

old

young

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Interaction of a spiral galaxy with its environment

• Gravitational interaction galaxy - cluster

• Gravitational interaction galaxy - galaxy

• Ram pressure galaxy ISM – intraclustermedium (ICM) (Kenney et al. 1995)

(Böhringer et al. 1994)

(Kenney et al. 2004)

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Ram pressure stripping & color

evolution

Ram pressure stripping partly responsible for cluster spirals in “green valley” & “red sequence”Crowl et al. 2012

Contours: generalSDSS galaxiesPoints: ram pressurestripped Virgo spirals

Galaxies with good evidence for RPS:

Quenching timesfrom spectraNo spectra

(slide from J. Kenney)

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Atomic gas: the HI view(Chung et al. 2009) (Bravo-Alfaro et al. 2000)

HI deficiency = log((expected HI mass)/(observed HI mass))

Cluster spirals are HI deficient and show truncated gas disks

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Molecular gas: the CO view(Kenney & Young 1989) (Boselli et al. 1994)

Cluster spirals are NOT CO deficient

Even the CO detection rate of Virgo early type galaxies is NOTdifferent from that of the field (Atlas3D; Young et al. 2011)

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Star formation: the Hα view« normal » Hα disks (Koopmann & Kenney 2001,2004)

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Star formation: the Hα view(Koopmann & Kenney 2001, 2004)

anemic Hα disks anemic truncated Hα disks

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Star formation: the Hα view(Koopmann & Kenney 2001, 2004)

truncated Hα disks

cluster radial profiles

52 Virgo galaxies: 37% normal, 6% anemic, 6% enhanced, 52% truncated

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The Virgo Cluster

• Distance: ~17 Mpc• 1’ = 5 kpc• Velocity dispersion:

~700 km/s• Dynamically young

cluster• Mass: ~1014 Msolar

at R=1 Mpc• Mgas/Mtot ~ 14%• Mgal/Mtot ~ 4%• M/L ~ 500

(Schindler et al. 1999)

Greyscale: X-ray Contour: galaxy density

3.5Mpc

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Virgo - Coma

• D=17 Mpc• Mass: ~1014 Msolar

at R=1 Mpc• Velocity dispersion:

~700 km/s • Large spiral fraction• One central galaxy• Asymmetric overall ICM

distribution• Dynamical young cluster

• D=100 Mpc• Mass: ~5 1014 Msolar at

R=1 Mpc• Velocity dispersion:

~1200 km/s• Small spiral fraction• Two central galaxies• Symmetric overall ICM

distribution• « relaxed » cluster

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Interaction diagnostics

• Which interaction is responsible for the observed distorsions/perturbations?

• Determination of the interaction parameters

• Means: HI maps and velocity fields, dynamical simulations, polarized radio continuum emission, photometry+ spectroscopy + stellar population synthesis

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Polarized radio continuum emission –a new diagnostic tool for interactions

• Polarized radio continuum emission is proportional to the density of relativistic electrons and the strength of the large-scale regular magnetic field: PI αααα neB2-4

• Polarized radio continuum emission is sensitive to shearand compression motions

NGC 4522(Kenney et al.2004)

Grey: opticalContour: HI

(Vollmer et al.2004)

Grey: HIContour: polarized

radio continuumemission

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First survey of 8 Virgo cluster spiral galaxies in polarized radio continuum emission

• 8 bright Virgo spiral galaxies

• 90h of VLA observations• 20cm C array; 6cm D array

• Resolution: ~20’’

• Sensitivity: 10µJy/beam at 6cm

B. Vollmer, M. Soida, R. Beck, C. Chyzy, K. Otmianowska-Mazur, M. Urbanik, J. van Gorkom, J. Kenney

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VLA 6cm polarized radio continuum emissionD

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Greyscale: optical B band; contour: 4.85GHz polarized radio continuum emission

Vollmer et al. (2007)

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MHD simulations

• Solve the induction equation on the velocityfields of the sticky particlesimulations evolution of the large scale regular magneticfield

• Assume relativistivelectron distribution evolution of the polarizedradio continuum emission

(with M. Soida and K. Otmianowska-Mazur)

grey: HI, contours: PI(Vollmer et al. 2006)

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VIVA = VLA Imaging of Virgo in Atomic Gas(A. Chung, J. van Gorkom, J. Kenney, H. Crowl, B. Vollmer)

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Numerical simulations• ISM-ICM interaction + gravitational interaction• turbulent/viscous stripping (Nulsen 1982; timescale ~1Gyr)

ram pressure stripping (momentum transfer; timescale ~10Myr)• constant time dependent ram pressure• Models: (i) Eulerian hydro (2D, 3D),

(ii) SPH,

(iii) sticky particles

(Roediger & Hensler 2005, Roediger & Brueggen 2006/2008,

Marcolini et al. 2003)

(Abadi et al. 1999, Schulz & Struck 2001)

(Vollmer et al. 2001)

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Comparison between the different codesface-on stripping

Conclusion: models are consistent within a factor 2: Gunn & Gott works

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Simulations with time dependent ram pressure

• depends on galaxy orbits within the cluster• simulations of galaxy orbits in the Virgo cluster and

determination of temporal ram pressure profiles

galaxy orbits

temporal ram pressure profile (ρv2)

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Normalization of the codeboxes: Cayatte et al. (1994); stars: simulations

truncated diskwith a 1/R profile

Conclusion: whatever you do with the disk, you will end up with a truncatedgas disk

Vollmer et al. (2001)

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Comparison between the models and the observations

• Known: systemic velocity, distance from cluster center, i, PA, gas distribution and velocity field

• Unknown: maximum ram pressure, time to maximum, angle between galactic disk and ram pressure wind

Ram pressure stripping criterion:Gunn & Gott (1972): Σgas vrot

2/R = ρICM vgal2

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A case study: NGC 4522• Distance from M87:

3.3o ~ 1 Mpc• Radial velocity:

+1000km/s w.r.t. M87• View: edge-on

(Kenney et al. 2004)

(Vollmer et al. 2004)

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NGC 4522: the « best fit » model

to observer

incl

i

image plane

wind direction

galactic plane

WEST

EAST

+RA

DEC

inclPA

αααα

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NGC 4522: final resultmodel HI

Greyscale: gas; Contours: polarized radio continuum emission

(Vollmer et al. 2007)

near peak ram pressure stripping

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NGC 4522: peak ram pressure stripping +projected distance of ~1 Mpc

moving intracluster medium due to infallof the M49 group of galaxies

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Observational gas characteristics• Asymmetric ridge of polarized radio continuum emissionat the outer disk (all)

• Gas disk truncated near the optical radius, asymmetricouter disk with tail structure (NGC 4501, NGC 4330)

• Truncated gas disk + extraplanar, high surface brightness gas (NGC 4522, NGC 4438)

• Truncated gas disk + extraplanar, very low surface brightness gas (NGC 4388)

• Truncated gas disk + perturbed, low surface brightnessarms (NGC 4569)

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Gas disk truncated near the optical radius, asymmetric outer disk with tail structure pre-peak stripping

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NGC 4501observations

HI

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grey: HI, contours: PI

HI

NGC 4330observations

Vollmer et al. (2008)

model

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Strongly truncated gas disk + extraplanar, high surface brightness gasnear peak stripping

NGC 4522 (Vollmer et al. 2006) NGC 4438 (Vollmer et al. 2005)

CO(1-0) IRAM30m

model:Gravitational interaction+ ram pressure

model observations

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Truncated gas disk + extraplanar, very low surface brightness gas~100Myr after ram pressure peak

NGC 4388

model observations

(Vollmer & Huchtmeier 2003)

(Oosterloo & van Gorkom 2005)

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NGC 4569Contours: HI VLA C+DGreyscale: B band

(Vollmer et al. 2004)

Truncated gas disk + perturbed, low surface brightness arms~300Myr after ram pressure peak

NGC 4569

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

model model

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Ram pressure stripping time sequenceVollmer (2009)

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Independent confirmation of stripping ages

• NGC 4522 (Crowl & Kenney 2007, 2008)

• NGC4569 (Boselli et al. 2007)

GALEX UV

WIYN SparsePack& GALEX UV

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The 3D viewVollmer (2009)

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Tidally enhanced ram pressure stripping

(Phookun & Mundy 1995)

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HI gas distribution HI velocity field

NGC4654

NGC4639

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NGC 4654

model I:ram pressure

model II:ram pressure +tidal interaction

HI observations(Phookun & Mundy 1995)

(Vollmer 2003) gas distribution velocity field

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NGC 4654 – PI modeltidal interaction + ram pressure stripping

(Vollmer 2003 & Soida et al. 2006)

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Ram pressure and the multiphase ISM

• Inside the truncationradius, gas disks arenormal

• Slight enhancedmolecular fraction in 3 galaxies (NGC4330, NGC4501, NGC4522)

Molecular gas fraction

Radio deficit region

PI

PI

Radio deficit: Murphy et al. (2009)

(Vollmer et al. 2012)

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Ram pressure and the multiphase ISM

• The ISM ismoved as an entity

• GMC lifetime < ram pressuredynamical time-scale

NGC4330

Amramsonet al. (2011)

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Ram pressure stripping of the multiphase ISM

• IRAM 30m HERA CO(2-1) observations

Dashed: HI (Kenney et al. 2004)Solid: CO(2-1)

model

modeldeprojection

faint COemission

Vollmer et al. (2008)

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(Vollmer et al. 2005)

Ram pressure stripping of the multiphase ISM

• NGC 4438: decoupeledmolecular clouds

• NGC 4402 (Crowl et al. 2005)

Contour: 20cm radio continuum emission; Greyscale: B band

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Ram pressure stripping of the multiphase ISM

• NGC 4438: diffuse ionized gasstripped more efficiently thanneutral gas

• Role of gravitational interaction?

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Velocity differenceHα - CO

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Star formation in the stripped gas

Greyscale: CO(2-1)Contours: Hα (Kenney et al. 2004)

Greyscale: HαContours: HΙfrom Kenneyet al. (2004)

modelGreyscale: HαContours: HI

Vollmer et al. (2008)

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Star formation in thestripped gas

NGC4330

NGC4501

NGC4522

NGC4654

NGC4438

SFR timescale spectral index

SFR timescale

• Except for N4438, clusterenvironment does not changeSFRmol=SFR/Mmol

• NGC4330, NGC4438, N4522show a depressed SFEtot in theextraplanar regions

• NGC4501, NGC4654 showregions of low SFEtot within thedisk with steep spectral index

Vollmer et al. (2012)

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VLA large proposal: survey of 19 Virgocluster spiral galaxies in polarized radio

continuum emission

• 19 Virgo spiral galaxies

• ~200h of VLA observations• 20cm C array; 6cm D array

• Resolution: ~20’’

• Sensitivity: 10µJy/beam at 6cm

B. Vollmer, M. Soida, R. Beck, C. Chyzy, K. Otmianowska-Mazur, M. Urbanik, M. Wezgowiec, J. van Gorkom, J. Kenney

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Symmetric spirals

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Radio halos

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Asymmetricdistributionsof polarizedradio continuumemission

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Conclusions• Polarized radio continuum emission is a useful tool for

interaction diagnostics• Efficiency of ram pressure stripping is ~1 (Gunn & Gott

works) – overall the ISM is stripped as an entity• For NGC 4522 a moving ICM is needed• Temporal ram pressure sequence in the Virgo cluster • Stellar population synthesis models confirm model

stripping ages (NGC 4388, NGC 4569, NGC 4522; PhDthesis of H. Crowl, Yale)

• Indication of different stripping efficiencies of diffuse ionized ISM under certain circumstances

• Ram pressure quenches star formation• Ram pressure stripping plays an important role in the

evolution of Virgo cluster spirals