Prsentation PowerPoint

1
When starbursts meet clusters of galaxies

• ISOCAM team
• Dario Fadda
• David Elbaz
• Alberto Franceschini
• Andrea Biviano
• Catherine Cesarsky
• Alan Moorwood
• Bianca Poggianti
• et al

• XMM-LSS team
• Marguerite Pierre (PI)
• Spitzer/SWIRE Team
• Carol Lonsdale (PI)

Pierre-Alain Duc (AIM - CEA-Saclay)
La Thuile, March 2005
Rencontres de Moriond, When UV meets IR
2
When starbursts meet clusters of galaxies

• ISOCAM team
• Dario Fadda
• David Elbaz
• Alberto Franceschini
• Andrea Biviano
• Catherine Cesarsky
• Alan Moorwood
• Bianca Poggianti
• et al

• XMM-LSS team
• Marguerite Pierre (PI)
• Spitzer/SWIRE Team
• Carol Lonsdale (PI)

Pierre-Alain Duc (AIM - CEA-Saclay)
La Thuile, March 2005
Rencontres de Moriond, When UV meets IR
3
(A lack of) activity in clusters of galaxies

• Clusters of galaxies an a priori hostile
  environment for the galaxy activity
  (star-formation, AGN)
• Infalling galaxies suffer
• Ram pressure gt ISM lost
• Strangulation gt External Gas reservoir lost)
• Harassment gt Disk destroyed stars lost

Ram pressure stripping of the galaxy ISM by the
ICM

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

Courtesy of B. Moore
Harassment
4
(Some) activity in (nearby) clusters of galaxies
Outskirts of clusters
Merging clusters
Ferrari et al., 2005
Location of the emission-line galaxies in the
merging cluster Abell 3921
Virgo cluster of galaxies HI contours on X-ray
map
5
(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? Clustering of distant mid-IR sources?
6
The infrared view of the activity in clusters

• IRAS (20 years ago)

• ISO (10 years ago)

• Spitzer (present)

• The first infrared maps of a few intermediate-z
  clusters evidence for a significant dust
  enshrouded activity LIRGs in clusters
• See 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

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

7

• Abell 1689
• at z0.18

HST/ACS
8
Star-forming activity in Abell 1689
Duc et al. 2000
9
Star-forming activity in Abell 1689
Duc et al. 2000

• A population of dust enshrouded SF galaxies?

10

• ISOCAM 15 mm observations of J1888.16 CL
  (z0.56)
• - discovered on deep optical AAT plates detected
  in the X-rays by ROSAT (Lx1.7 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
11

• ISOCAM 15 mm observations
• of J1888.16 CL (z0.56)

• 8 15 mm sources
• associated with spectroscopically confirmed
  cluster members

12
Star Formation Rate (Mo/yr)
Ellipticals at z0.6
Scd,irr at z0.6
Cluster members
Background/foreground
Infrared Luminosity (Lo)

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

13
Spectroscopic properties of the LIRGs in
J1888.16CL

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

Histogram of optical spectral type
(Poggianti et al., 2001)
14

• 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)
• -gt too many given the percentage of field LIRGs

• Within the cluster itself ?
• Velocity dispersion of MIR sources
• 700520-260 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 enough
• Effect of the global tidal field on infalling
  groups (Bekki, 1999)
• or during cluster-cluster merger (Miller, 2003)

15
(Much more) activity in (distant) clusters of
galaxies
Coia et al., 2004
ISOCAM 15micron map of CL00241654 (z0.39)
16

• Conclusions (ISO based)
• From mid-infrared ISOCAM data
• Evidence for a dust enshrouded activity in
  nearby cluster of galaxies (Abell 1689, z0.18)
• Discovery of even more active Luminous Infrared
  Galaxies in intermediate redshift clusters (i.e.
  J1888.16CL, z0.56)
• 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

17
When X-ray meets IR

• 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 maps
• of 9 sq degree.
• Observed Aug 2004
• .
• CFHTLS optical ugriz Megacam images at CFHT
• VVDS optical VLT/VIMOS spectra
• TISWAZ optical 2dF spectra

18
XMM-Newton true color map of D1 field
19
XMM-Newton true color map of D1 field
20
XMM-Newton true color map of D1 field