1 / 14

Orbital Poles of Milky Way Satellites (based on Palma, Majewski and Johnston 2002)

Orbital Poles of Milky Way Satellites (based on Palma, Majewski and Johnston 2002). Nick Cowan UW Astronomy February 2005. Dramatis Personae. Globular Clusters Red Horizontal Branch (RHB) Blue Horizontal Branch and Metal Poor (BHP+MP) Dwarf Satellite Galaxies (DSG). Bottom-Up

yakov
Download Presentation

Orbital Poles of Milky Way Satellites (based on Palma, Majewski and Johnston 2002)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Orbital Poles of Milky Way Satellites(based on Palma, Majewski and Johnston 2002) Nick Cowan UW Astronomy February 2005

  2. Dramatis Personae Globular Clusters • Red Horizontal Branch (RHB) • Blue Horizontal Branch and Metal Poor (BHP+MP) Dwarf Satellite Galaxies (DSG)

  3. Bottom-Up Small-scale (GCs, DSGs) form first. Small pieces coalesce into a galaxy. Top-Down Galaxy forms first GCs and DSGs form in the context of a large galaxy. Galactic Formation Schemes

  4. Pole Analysis

  5. Orbits will not be perfectly correlated: • Even in a spherical potential, tidal forces will degrade orbits. • Potential is probably not spherical so we expect precession of orbits. • Clumpy dark matter will scatter satellites. • A time-dependant potential will scatter satellites.

  6. Great Circle Pole Families

  7. Crossing Points of Great Circles

  8. Correlation Function and [Fe/H] RHB and DSG BHB/MP and DSG

  9. Correlation Function and Rgc Rgc > 25 kpc 8 < Rgc < 25 kpc

  10. Arc Segment Family Analysis

  11. Determining Arc Segment Families • Find the two nearest arc segments. • Lump them together. • Find the next-nearest arc segments. • Lump them together. • etc. • Stop when you stop believing.

  12. How far is too far? “I’m getting nervous, let’s stop here.”

  13. Reality Check

  14. Conclusions • BHB+MP GCs do not appear to track DSGs in their orbits around the MW. • Some RHB GCs have correlated orbits. • Orbital Pole Analysis is a powerful tool but better proper motion measurements will be needed to put more meaningful constraints on Galaxy formation schemes.

More Related