10. Their explanation
• Non-emission-line galaxies have been
around the cluster environment for longer
• Emission-line galaxies have only recently
entered and retain memory of their infall
13. Millennium + SAMs
1000 clusters with M200 > 2 x 1014 Msun
1 million galaxies
Colour
Star formation
Age
14. Anisotropy at z=0
Global values:
β = 0.257± 0.03
β = 0.352± 0.04
β = 0.191± 0.03
Populations selected by
colour:
u-i>2.5 / u-i<2.5
15. Member galaxies
of the high-z clusters
Progenitors of z=0 galaxies
at high z
Anisotropy at z>0
16. Anisotropy at z>0
Galaxies surviving till z=0 are characterised by a much lower β at
high z with respect to the full population
(particularly evident for galaxies that are blue at z=0)
17. Anisotropy at infall
Member galaxies
of the high-z clusters
Progenitors of z=0 galaxies at high z
Progenitors of blue gals at z=0
Progenitors that are blue at infall
18. Anisotropy at infall
Progenitors of blue gals at z=0
Progenitors that are blue at infall
Galaxies surviving till z=0 enter the clusters with a much lower β
The anisotropy at infall
grows going towards z=0
19. Anisotropy vs. infall time
Infall
(see previous plot)
z = 0.7 (6.1 Gyrs)
z = 0.5 (5 Gyrs)
z = 0.3 (3.5 Gyrs)
z = 0.2 (2.4 Gyrs)
z = 0.1 (1.4 Gyrs)
z = 0
Anisotropy of
galaxies grouped
by zinfall
20. Anisotropy vs. infall time
Infall
(see previous plot)
The anisotropy of
galaxies increases
after entering the
cluster
(especially in the first
2 Gyrs)
29. Individual orbits
500 galaxies and their full history
integrate the orbits given initial position and velocity
CASE A CASE B
30. Individual orbits
500 galaxies and their full history
integrate the orbits given initial position and velocity
CASE A CASE B
31. Individual orbits
500 galaxies and their full history
integrate the orbits given initial position and velocity
CASE A CASE B
32. Individual orbits - examples
Mass inside rsatellite vs. time_________ orbit
____ bound orbit
original orbit
CASE A - fixed mass
CASE B - varying mass
1.5 · 1014
M
4.9 · 1014
M
33. Individual orbits - examples
_________ orbit
____ bound orbit
Mass inside rsatellite vs. time
3.4 · 1014
M
5.2 · 1014
M
34. Individual orbits - examples
_________ orbit
____ bound orbit
Mass inside rsatellite vs. time
7 · 1013
M
2.7 · 1014
M
35. Individual orbits - examples
Mass inside rsatellite vs. time
_________ orbit
____ bound orbit 1.6 · 1014
M
9.8 · 1013
M
36. Individual orbits - examples
Mass inside rsatellite vs. time
_________ orbit
____ bound orbit
8 · 1013
M
1.4 · 1014
M
39. Summary
• At z=0, blue galaxies have lower β than red galaxies
• Galaxies that are blue at z=0 entered the cluster
with a much lower β than average
• The anisotropy of member galaxies increases once
these enter the cluster environment
(It could be a natural evolution of the orbits when
sgalaxies move in an ever-deeper potential well)
43. Maybe a hint from Rocha et al. (2011)?
Figure 5. Tangential velocity as a function of infall time for subsamples of subhalos with similar radial velocities
and galactocentric distances to those of the given dwarf galaxies. The subsample selection criterion is the same
as in Fig. 4. The 1-sigma uncertainties in the proper motions are represented by the shaded regions. The
addition of proper motion constraints provides a better estimate of the infall time than radial velocity alone.
46. Simulations
• Very similar anisotropy profiles at z=0
(both shape and global β)
• No evidence of evolution at higher z
• No evidence of progenitors having
higher β than their z=0 descendants
49. Jeans analysis
Assume models for
NFW - concentration c
Mamon-Lokas or Osipkov-Merritt - anisotropy radius a
M(rn), β(rn)
50. Mamon-Lokas or Osipkov-Merritt - anisotropy radius a
Assume models for
Jeans analysis
NFW - concentration c
M(rn), β(rn)
from Mamon&Lokas (2005)
Mamon-Lokas
Osipkov-Merritt
51. Jeans analysis
Use 2 independent tracers of the cluster potential
(Battaglia et al. 2008)
ELG & nELG
Solve the equations separately for each component
Minimise χ2
= χ2
nELG + χ2
ELG c
Use c and do it again a and a
