Presentacin de PowerPoint

1
Satellite Galaxies in numerical simulations
I Results at z0
Laura V. Sales
2

• This talk is organized as follows
• Milky Way review
• Why satellite galaxies are important?
• Our results using numerical simulations
• Future Work

3
What would you do with US 100000000000?
(and fill it with beautiful women)
4
What would you do with US 100000000?
But why not to buy your own galaxy?
5
Buying the galaxy
Famous galaxies Store
6
So Let us begin with the first question
Type of galaxy elliptical or
spiral
7
Spiral Galaxy (Full)

• A barred bulge (the MW appears to have a
  bar of
• 3.5-4.5
  Kpc placed at 20- 40 angle to the
• 
  sun-galactic center direction)
• Not one but TWO disk component!
• Thin disk containing more than 90 of
  the disk baryons and the youngest
  
• stars. Also
  concentrates almost all the angular momentum.
  Typical
• scale height
  300 pc
• Thick disk stars older than 12 Gyr
  and more metal poor than thin disk stars.
• Typical scale
  height 1Kpc
• A plus of old stars! We give you for free up
  to 1 of the total stellar mass
• 
  ( 109 Msun) in the form of old-metal poor
  stars
• 
  distributed spherically into the stellar
  halo.
• Star clusters Satellite galaxies Find much
  more fun in your galaxy
• trying to understand how,
  when, why open and globular clusters had
• formed!. Satellites can also
  provide tricky evidence of what is going on in
  
• the outer parts of your
  galaxy!!!.

Would you like to enlarge your combo??? For only
50 we also include a fantastic central Black
Hole of MBH2.6x106 Msun
8
(No Transcript)
9
Why satellite galaxies are important?
10
Why satellite galaxies are important?
Within the hierarchical galaxy formation
scenario, satellites are the building blocks of
galaxies
Those who survive until the present
Those who had merged with the host at early times
Impact on typical star ages of the host components
11
Why satellite galaxies are important?
Within the hierarchical galaxy formation
scenario, satellites are the building blocks of
galaxies
Those who survive until the present
Those who had merged with the host at early times
Direct observational tests!
12
Some examples of this in the MW...
13
Milky Way satellites
(11 confirmed satellite galaxies within 300 Kpc)
MW
14
MW and M31 satellite magnitudes (MV)
15
The simulations

• High resolution Nbody SPH code
• Scenario LCDM universe
• Particle mass resolution
• DM particles mpdrk 1.2x107 Msun
• Gas particles mpgas 2x106 Msun
• Distance resolution 0.5 Kpc

16
Mgas 1-2 Mstr 9-20 Mdrk 85-90
17
Galaxy formation scenario
18
Scatter mario
19
Our results

• Satellite velocities
• 2) How isotropic are satellite orbits?
• 3) How are satellite radially distributed?

20
1) Satellite Velocities
Once appropriately scaled, satellite velocities
have Gaussian distributions within Rvir
21
2) How circular are satellite orbits?
Anisotropy parameter
b1-(sT2/2sr2)
Binney Tremaine 1987
22
How circular are satellite orbits?

• Satellite orbits are increasing radially
  anisotropic, with a typical value of b 0.4,
  quite similar to the DM particles.
• Satellites behave consistently with the DM
  particles, however halo stars are characterized
  by very radial orbits in the external regions.

23
Comparison with MW satellites
24
How can we use this?
25
By doing this what we get is
Not so bad! ?
26
We could try the same with our nearest neighbour
(M31)...
Most probable values for M31 Vvir 260
Km/s Rvir 522 Kpc Mvir 7x1012 Msun
27
3) Satellite radial distribution
Using our previous estimations of Rvir for MW and
M31 we find very good agreement between simulated
satellites and real satellites radial
distributions...?
28
How is related the satellite radial distribution
with the DM distribution?
But... What about other luminous tracers?
29
Comparing different possible tracers of the DM
halo
MW

• Globular clusters and simulated stellar halo
  have very similar distributions, with a density
  profile rr-3.5. Satellites and DM have a steeper
  r a r-2.
• Satellite galaxies are the best
• DM tracers in the outer galaxy halo.

(simulations)
30
Future Work

• How does satellite population evolutionate with
  time?
• Which satellites have the largest probabilities
  of surviving?
• Does the initial orbital parameters change when
  satellites orbit their host?
• What can survival population of satellties tell
  us about their infall redshift?

31
Many thanks for your attention