Pr

1
Pierre-Alain Duc Recycling in the galaxy
environment
F. Bournaud J. Braine U. Lisenfeld P. Amram P.
Weilbacher
Chania, Crete, August 2004 The environment of
galaxies
2
Looking between galaxies
_at_ Gregg West
3
Stars in the intracluster medium

• Diffuse light
• Streams, filaments revealed by deep imaging
• Resolved stellar populations
• Giant red stars (HST detections)
• Planetary nebulae (Narrow-band optical images
• Spectroscopic confirmation)
• ULXs, Supernovae

Gregg West, 1998
Arnaboldi et al., 2002

• Between 10 and 50 (20) of the stellar mass in
  the ICM

4
(No Transcript)
5
Intergalactic molecular hydrogen
IRAM 30m CO(1-0)
Stephans quintet

• More than
• 2.2 x 109 Mo
• of H2 outside
• galactic disks

CO(1-0)
HST/Gallagher et al., 2001HI Williams et al.,
2002 COLisenfeld et al., 2002
6
Intergalactic molecular hydrogen
7
Intergalactic ionized hydrogen
8
Intergalactic ionized hydrogen
9
Intergalactic star forming regions

• Emission line regions detected in Ha images
• - Diffuse
• Extended
• EL dots
• A range of star-formation rates
• 0.001 to 0.1 Mo / yr

NGC 5291
Gavazzi et al., 2001
Bournaud et al., 2004
Ryan-Weber et al., 2004
10
Intergalactic recycling

• HI -gt H2 -gt stars -gt HII

• HI
• Old stars
• Young stars

11
Super Star Clusters, Globular Clusters in tidal
debris
Weilbacher et al., 2002
Duc Mirabel, 1995
Observations
Hibbard Barnes., 2004
Elmegreen et al., 1993
Simulations
12
Tidal Dwarf Galaxies
HI

• 109 Mo end-of-tail bound, gaseous
  accumulations

13

• Kinematical signature
• of end-of-tail projection effects

Simulations

• Streaming motions a change in the velocity
  gradient before the end of the tail may reveal
  projection effects

Bournaud et al., 2004
14

• Kinematical signature
• of end-of-tail projection effects

Bournaud et al., 2004
Observations

• Projection effects cannot account for all massive
  end-of-tail accumulations some of them are real

15
Reproducing the structure of tidal tails
Truncated DM halo
Stars 15kpc (50,000) Gas 35 kpc
(100,000) Dark matter halo 45 kpc (100,000)
16
Extended DM halo
Reproducing the structure of tidal tails
Stars 15kpc (50,000) Gas 35 kpc
(100,000) Dark matter halo 150 kpc (100,000)
17
Reproducing the structure of tidal tails with
high-resolution simulations

• Stars 106 particles
• Gas 106 particles
• Dark matter halo
• 150 kpc (2 x 106)
• Full N-body
• (dissipation, self-gravity,
• Star formation, feedback)
• Vectorial computer
• NEC-SX6 CCRT CEA

Extended dark matter halo required
18
Reproducing the formation of Tidal Dwarf Galaxies
Gas
NGC 7252
Stars
Duc, Bournaud Masset, 2004

• M 2 x109 Mo

• M 109 Mo

Observations
N-body simulations
19
Simulations
Observations
20
The formation of Tidal Dwarf Galaxies
Simulations
Duc, Bournaud Masset, 2004

• without self-gravity

• without gas dissipation

• The
  proto-TDGs are still formed!
• Their origin is fundamentally kinematical only
  later self-gravity takes over, and the clouds
  collapse

21
The role of the extended dark matter halo
Extended halo
Halo tronqué Potential of an
isothermal sphere
Keplerian potential

• According to the shape of the tidal field, matter
  from the external disk is either diluted or
  transported keeping its original surface
  brightness. This creates a density enhancement at
  the origin of the proto-TDGs

22
Radial excursions of tidal material with an
extended/truncated halo
Constant density
Dilution
Duc, Bournaud Masset, 2004
23
The role of a dark matter baryonic component
If existing in the disk, it should also be
present in tidal tails, and in particular in TDGs
NGC 5291 (optique HI)
Bournaud et al., 2004

• Internal kinematics of tidal tails and TDGs -gt
  dynamical mass, compared to the luminous mass

24
Conclusions

• All material available to fuel intergalactic
  star-formation
• Stripped, pre-enriched HI, transformed into H2
  and stars
• Recycled gravitationally bound objects formed
  out of tidal debris around interacting systems
  and mergers
• Observations and simulations two types of tidal
  objects, with different physical origins
• 106 - 108 Mo, distributed all along the tails,
  progenitors of Super Star Clusters and/or
  Globular Clusters, formed from growing local
  gravitational instabilities
• 109 Mo, at or near the tip of tidal tails,
  progenitors of Tidal Dwarf Galaxies, with a
  kinematical origin, formed within extended Dark
  Matter haloes, according to a top-down scenario