11/16/2018 Probing the Galactic Potential Using the μarcsec astrometric observations of Disk Stars T. Sumi (Nagoya STE) K.V. Johnston (Columbia) S. Tremaine (IAS) D.N. Spergel (Princeton)
MOA-II1.8m telescope （New Zealand/Mt. John Observatory at NZ, 44S ） 11/16/2018 MOA-II1.8m telescope （New Zealand/Mt. John Observatory at NZ, 44S ） Mirror : 1.8m CCD : 8k x 10k pix. FOV : 2.2 square deg.
MACHO fraction depends on halo model 11/16/2018 MACHO fraction depends on halo model
Proper motion 11/16/2018 ~300 I-band frames, 4years ~1mas/yr
Streaming motions of the bar 11/16/2018 Streaming motions of the bar Sun Color Magnitude Diagram faint bright Vrot=~50km/s
SIM Key Project: Taking Measure of the Milky Way 11/16/2018 SIM Key Project: Taking Measure of the Milky Way Steven Majewski (Virginia) [John Bahcall (IAS)] Doug Geisler (Concepción) Wolfgang Gieren (Concepción) Eva Grebel (Basel) Carl Grillmair (Caltech) Kathryn Johnston (Wesleyan) Ricky Patterson (Virginia) I. Neill Reid (STScI) David Spergel (Princeton) Scott Tremaine (Princeton) Takahiro Sumi (Princeton) Jeff Crane (OCIW) Peter Frinchaboy (Virginia) Ricardo Muñoz (Virginia) Clara Moskowitz (Wesleyan) Christina Hampton (Virginia) David Nidever (Virginia) Roberta Johnson (Caltech) Mei-Yin Chou (Virginia) Cameron Hummels (Wesleyan) Mike Siegel (Texas) Tony Sohn (Korean Astro Obs) Kyle Westfall (Wisconsin) David Law (Caltech) Bill Kunkel (Carnegie) James Bullock (UC-Irvine) Rachael Beaton (Virginia) SIM Science Team Meeting – Washington 8 January 2006
KP Proposed Scope (1999) 11/16/2018 Mass Potential of Galaxy (tidal tails & satellites in halo) Mass and Mass Distribution (shape, radial profile) of MW “Lumpiness” of the Halo Dynamics of the Disk Surface Mass Density (Oort limit) Milky Way Rotation Curve Dynamics of the Central Galaxy Dynamics of Bulge Orientation and Motions of the Bar Fundamental and Legacy Measurements Proper motions of every known MW satellite galaxy & globular Proper motions for large number of selected open clusters Solar rotation speed, p & dynamical distance to GC
Halo & Disk model Halo mass: Disk density: Radial dispersion: 11/16/2018 Halo & Disk model Hernquist 1990 Halo mass: Disk density: Radial dispersion:
Spiral arms model m:number of spirals K=C/R:radial wave number 11/16/2018 Spiral arms model Potential: Radial verlocity: m:number of spirals K=C/R:radial wave number p:pattern speed :epicyclic frequency F:reduction factor
11/16/2018 Parameters (kpc)
11/16/2018 Disk stars
SIM Mission time & the number of targets 11/16/2018 SIM Mission time & the number of targets 240hr 10μas N=810
Markov Chain Monte Carlo 11/16/2018 Markov Chain Monte Carlo Likelihood: n:number density of stars V:volume ~p-4(p-3)
Provability distribution of p 11/16/2018 Provability distribution of p V~p-3
Recovery by MCMC. (N=810) 11/16/2018
11/16/2018 Consistency Check 10 MCMC runs
Accuracy v.s. Numer of stars 11/16/2018
Accuracy v.s. parallax accuracy 11/16/2018
11/16/2018 Disk stars
Accuracy v.s. 11/16/2018
Summary SIM can constrain Rotation curve in 3% up to 20 kpc δMN-1/2 11/16/2018 Summary SIM can constrain Rotation curve in 3% up to 20 kpc δMN-1/2 δM do NOT depnd on δp until 500μas should be >60 Knowing the error distribution is important APOGEE, RVs with <0.5 km/s for 1-2 x 10^5 stars
Likelihood surface. (N=810) 11/16/2018 68%,95%CL.
11/16/2018
2005: Satellite Galaxy Tails 11/16/2018 Extensive new data on Sgr tidal streams 2 new wraps of debris (Pakzad et al. 2005) Evidence for interaction w/LMC 2 Gyrs ago (Majewski, Nidever et al., in prep) Proper motion predictions for the LMC-Sgr interaction made. Extensive RV survey of Sgr core (~1500 stars)