When starbursts meet clusters of galaxies…

Starbursts in clusters of galaxies

When starbursts meet clusters of galaxies…

La Thuile, March 2005Rencontres de Moriond, “When UV meets IR”

Pierre-Alain Duc(AIM - CEA-Saclay)

• ISOCAM teamDario FaddaDavid ElbazAlberto FranceschiniAndrea BivianoCatherine CesarskyAlan MoorwoodBianca Poggiantiet al…

• XMM-LSS teamMarguerite Pierre (PI)

• Spitzer/SWIRE TeamCarol Lonsdale (PI)


When starbursts meet clusters of galaxies…

La Thuile, March 2005Rencontres de Moriond, “When UV meets IR”

Pierre-Alain Duc(AIM - CEA-Saclay)

• ISOCAM teamDario FaddaDavid ElbazAlberto FranceschiniAndrea BivianoCatherine CesarskyAlan MoorwoodBianca Poggiantiet al…

• XMM-LSS teamMarguerite Pierre (PI)

• Spitzer/SWIRE TeamCarol Lonsdale (PI)


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• Clusters of galaxies: an a priori hostile environment for the galaxy activity (star-formation, AGN)

• Infalling galaxies suffer: Ram pressure => ISM lost Strangulation => External Gas reservoir lost) Harassment => Disk destroyed; stars lost

(A lack of) activity in clusters of galaxies(A lack of) activity in clusters of galaxies

Courtesy of B. Moore

Ram pressure stripping of the galaxy ISM by the ICM

Harassment

• Indeed, locally, the star formation activity is reduced in denser environments such as clusters-> HI deficiency-> SDSS results: a decline of the mean SFR as a function of local surface density


(Some) activity in (nearby) clusters of galaxies(Some) activity in (nearby) clusters of galaxies

Outskirts of clusters Merging clusters

Ferrari et al., 2005

Virgo cluster of galaxies: HI contours on X-ray map

Location of the emission-line galaxies in the merging cluster Abell 3921


(Much more) activity in (distant) clusters of galaxies(Much more) activity in (distant) clusters of galaxies

The “Butcher-Oemler” effect

As a function of redshift:• Increase in the fraction of blue galaxies (Photometric BO)• Increase in the fraction of spirals (Morphological BO)• Increase in the fraction of star-forming galaxies and post starbursts (Spectroscopic BO)

An environmental effect (role of the cluster; dynamics, ICM) or …

… a field effect (general evolution of galaxies falling in the cluster) ?

(A high level of) activity ? How obscured?(A high level of) activity ? How obscured?Clustering of distant mid-IR sources?Clustering of distant mid-IR sources?


• IRAS (20 years ago)• ISO (10 years ago)

The infrared view of the activity in clustersThe infrared view of the activity in clusters

• Spitzer (present)

• Faint infrared fluxes of galaxies located in the most nearby clusters (Virgo):no LIRGs/ULIRGs

• The first infrared maps of a few intermediate-z clusters: evidence for a significant dust enshrouded activity; LIRGs in clustersSee review by Metcalfe et al. (2005), Space Science Review ISO special issue

• Wide surveys: statistics on the amount of star formation in clusters of galaxies and their surrounding


• Abell 1689: Abell 1689:

at z=0.18at z=0.18

HST/ACS


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Chary & Elbaz, 2002

Duc et al. 2000

Star-forming activity in Abell 1689Star-forming activity in Abell 1689

Affected by obscuration,Metallicity, aperture effects


• A population of dust enshrouded SF galaxies?

Duc et al. 2000

Star-forming activity in Abell 1689Star-forming activity in Abell 1689




• ISOCAM 15 m observations of J1888.16 CL (z=0.56)

- discovered on deep optical AAT plates; detected in the X-rays by ROSAT (Lx=1.7 1044 erg/s); shows an excess of blue galaxies (BO effect)

• A strip of 3 x 15 arcmin (1.3 x 5.9 Mpc) in the LW3 band covering the outskirts of the cluster

- Ground-based follow-up:at ESO (WFI, SOFI, VLT)

• 44 MIR sources detected(redshift measured for 27 of them)

Duc et al., 2004


• ISOCAM 15 m observations of J1888.16 CL (z=0.56)

• 8 15 m sources associated with spectroscopically confirmed cluster members


• A population of Luminous Infrared Galaxies in J1888.16CL

Cluster members

Background/foreground

Star Formation Rate (Mo/yr)

Infrared Luminosity (Lo)

Ellipticals at z=0.6

Scd,irr at z=0.6


Histogram of optical spectral type

• Optical signature of dust enshrouded starburst, typical of luminous infrared starbursts

(Poggianti et al., 2001)

Spectroscopic properties of

the LIRGs in J1888.16CL


Where, when and how the cluster IR activity was triggered ?Where, when and how the cluster IR activity was triggered ?

• In the surrounding field ?: are the MIR sources recently accreted field LIRGS?

8 in 100 Myr (typical duration of LIR phase)-> too many given the percentage of field LIRGs

•Within the cluster itself ?

Velocity dispersion of MIR sources:700+520

-260 km/s

Possible mechanism: an initial shock-induced burst before the gas is stripped by ram pressure ?

•Within sub-groups, accreted along filaments ?

Possible mechanisms:

Tidal interactions: if the velocity dispersion is low enoughEffect of the global tidal field on infalling groups (Bekki, 1999)

or during cluster-cluster merger (Miller, 2003)


ISOCAM 15micron map of CL0024+1654 (z=0.39) Coia et al., 2004

(Much more) activity in (distant) clusters of galaxies(Much more) activity in (distant) clusters of galaxies


Conclusions (ISO based)Conclusions (ISO based)

• From mid-infrared ISOCAM data: Evidence for a dust enshrouded activity in nearby cluster of galaxies (Abell 1689, z=0.18)

Discovery of even more active Luminous Infrared Galaxies in intermediate redshift clusters (i.e. J1888.16CL, z=0.56)

Optical signature of dust enshrouded starbursts

Most active regions in the cluster outerskirts

• The triggering mechanism is still unclear: tidal collisions in falling sub-structures, cluster mergers ?

• An IR BO effect needs to be quantified: the role of Spitzer




• XMM -LSS: 10ks X-ray map with XMM-Newton of a large contiguous area (5 sq deg sofar)A sample of X-ray selected groups and clusters

• SWIRE: IRAC and MIPS mapsof 9 sq degree.Observed Aug 2004 …….

• CFHTLS: optical ugriz Megacam images at CFHT

• VVDS: optical VLT/VIMOS spectra

• TISWAZ: optical 2dF spectra

When X-ray When X-ray meets IR… meets IR…


XMM-Newton true color map of D1 field

Nearby group of galaxies

Valtchanov et al., 2005



Cluster merger at intermediate z


Distant X-ray clusters


Documents

When starbursts meet clusters of galaxies…