Rewinder

Presented at the Gaia Challenge 2 at the MPIA in Heidelberg.

Transcript

1. REWINDER Adrian Price-Whelan (Columbia University) Kathryn Johnston, David Hogg, Sarah Pearson, Andreas Küpper, Allyson Sheffield
2. Internal dynamics / disruption Underlying potential Streams encode info. about:
3. How to “fit” stream data? Need a generative model!
4. GRAVITY Progenitor Lagrange points
5. Stars Progenitor
6. Present Past Rewinder
8. Stripped star Progenitor
9. (Star orbit) - (Progenitor orbit)
10. x1 = ri · ˆ r prog ( t ) L prog (t), r prog (t), x3 = ri · ˆ L prog ( t ) x2 = ri · ˆ x2
11. Instantaneous orbital plane
12. Normalized by tidal radius
14. Incorrect potential
15. ✓ The disruption is simple?
16. ✓ At the (unknown) unbinding time for each star…
17. “The Pal 5 Challenge” with 4 stars: 3 leading arm 1 trailing arm
19. Previously… Price-Whelan et al. (2014) Nparams / 6Nstars Bug: Computationally can only use a few stars Feature: We can infer the potential with a few stars!
20. Price-Whelan et al. (2014)
21. Now Use importance sampling to marginalize over “true” phase-space positions of the stars Only params. of marginal likelihood are potential params., progenitor position, nuisance params. Price-Whelan et al. (in prep.)
22. Price-Whelan et al. (in prep.)
23. SMHASH Spitzer Merger History And Shape of the Halo RR Lyrae stars: intrinsic 2% scatter in P-L relation in IR Johnston, Madore, Majewski, Besla, Bono, Clementini, Cioni, Cohen, Freedman, Grillmair, Kallivayalil, Kollmeier, Law, Marengo, Mondon, Nidever, Pietrzynski, Persson, Price-Whelan, Rich, Scowcroft, Seibert, Smith, Sesar, Soszynski, Thompson, Udalski, van der Marel (Madore & Freedman 2012) (+ Spitzer Cycle 9 work)
24. SMHASH Debris targets: ~30 stars in Orphan stream ~100 stars in Sagittarius (Sgr) stream 2 Sgr globular clusters 20 Sgr core fields