The impact of LAMOST and other major surveys on the kinematic - PowerPoint PPT Presentation

The impact of LAMOST and other major surveys on the kinematic understanding of the solar neighbourhood Dynamics of Disk Galaxies Workshop Seoul National University Oct 24th, 2013 Martin C. Smith Shanghai Astronomical Observatory http://hubble.shao.ac.cn/~msmith/

How we can test theories of galaxy formation • LCDM has proved very successful in terms of large scale structure, Springel et al. (2008) but how accurate are simulations on galaxy scales ?

How we can test theories of galaxy formation • LCDM has proved very successful in terms of large scale structure, but how accurate are Bullock & Johnston (2005) simulations on galaxy scales ? • Predictions for the stellar halos are working well, but the disc is NGC474 significantly more complicated • The crucial question is how to constrain theories of disc formation and evolution using observations? • The ideal place to test these is the Milky Way , where we can amass large observational datasets

The SDSS view of the Milky Way

Progress is driven by large surveys • Cutting edge surveys have driven our understanding of the Milky Way for many years, from Herschel & Kapteyn to modern surveys like 2MASS, Hipparcos & Geneva-Copehagen Survey.

Progress is driven by large surveys • Cutting edge surveys have driven our understanding of the Milky Way for many years, from Herschel & Kapteyn to modern surveys like 2MASS, Hipparcos & Geneva-Copehagen Survey. Belokurov et al. (2006) • Without doubt the most prominent survey in the past decade has been SDSS

Progress is driven by large surveys • Cutting edge surveys have driven our Juric et al. (2008) understanding of the Milky Way for many years, from Herschel & Kapteyn to modern surveys like 2MASS, Hipparcos & Geneva-Copehagen Survey. • Without doubt the most prominent survey in the past decade has been SDSS • An hugely important series of papers were published by Juric & Ivezic in 2008, which constructed and refined photometric distance estimators

What have we learnt from SDSS • Once we have distances we can investigate the full kinematics, looking at the stellar halo (see also Bond et al., Klement et al, etc) Smith et al. Dinescu et al. (1999) 5 (2009)

What have we learnt from SDSS • Once we have distances we can investigate the full kinematics, looking at the stellar halo (see also Bond et al., Klement et al, etc) • SDSS told us a lot about the disc from the photometry, e.g. Newberg et al. (2002), Ivezic et al. (2008) 5

What have we learnt from SDSS • Once we have distances we can de Jong et al. (2010) investigate the full kinematics, looking at the stellar halo (see also Bond et al., Klement et al, etc) • SDSS told us a lot about the disc z (kpc) from the photometry, e.g. Newberg et al. (2002), Ivezic et al. (2008) Distance (kpc) 5

What have we learnt from SDSS • Once we have distances we can Smith et al. (2012) investigate the full kinematics, looking at the stellar halo (see also Bond et al., Klement et al, etc) 1.0 [Fe/H] (-0.5, 0.2) 0.9 (-0.8, -0.5) • SDSS told us a lot about the disc (-1.5, -0.8) from the photometry, e.g. Newberg 0.8 σ z / σ R et al. (2002), Ivezic et al. (2008) 0.7 0.6 • However, with full 6D phase-space we can probe the dynamics 0.5 0.0 0.5 1.0 1.5 2.0 |z| (kpc) 5

What have we learnt from SDSS Smith et al. (2012) • Once we have distances we can investigate the full kinematics, Visible + dark looking at the stellar halo (see also 140 140 matter models OM Bond et al., Klement et al, etc) M 120 120 H S • SDSS told us a lot about the disc N97 100 100 from the photometry, e.g. Newberg • pc -2 ) • pc -2 ) N I M Kuijken & et al. (2002), Ivezic et al. (2008) Σ (M O Σ (M O Gilmore 80 80 Smith et al. • However, with full 6D phase-space 60 60 we can probe the dynamics Visible matter model 40 40 • Although here I am concentrating on SDSS, significant contributions 20 20 0 0 1 1 2 2 3 3 4 4 have been made by other surveys, z (kpc) z (kpc) most notably GCS & RAVE 5

Dissection with alphas • Alpha elements are important tracers of the age of a population 0.6 • The daunting task of determining lo g 10 N [ α /Fe] for SDSS G-dwarfs was 0.5 1.0 1.5 2.0 2.5 1 1 . carried out Young-Sun Lee (2011a) 2 0 . 8 0 0.4 2.00 0.3 [ α /Fe] 1 . 0.2 2 0 2.10 1 . 2 0.1 0 2 . 0 0 0 . 8 1 0.0 -1.0 -0.5 0.0 [Fe/H] Figure 2. Lee et al. (2011a)

Dissection with alphas Lee et al. (2011b) 140 • Alpha elements are important N thin = 8062, ∆ V φ / ∆ [Fe/H] = -22.6 ± 1.6 0.1 ≤ |Z| < 3.0 kpc 260 tracers of the age of a population N thick = 5586, ∆ V φ / ∆ [Fe/H] = +45.8 ± 2.9 240 V φ [km s -1 ] 220 200 • The daunting task of determining 180 160 [ α /Fe] for SDSS G-dwarfs was 140 carried out Young-Sun Lee (2011a) -1.0 -0.5 0.0 [Fe/H] • Old stars behave as expected, but young stars exhibit opposite trend 0.6 (see also Loebman et al. 2011, Yu lo g 10 N 0.5 et al. 2012) 1.0 1.5 2.0 2.5 1.80 1 . 2 0 0.4 2.00 0.3 [ α /Fe] • This is a natural consequence of 1 . 0.2 2 radial mixing (not migration), with 0 2 . 1 0 1 0.1 . 2 0 eccentric orbits bringing in stars 2 . 0 0 . 8 0 1 0.0 from the outer- and inner-disc -1.0 -0.5 0.0 [Fe/H] Figure 2.

Velocity structure in the outer disc

Liu et al. (2012); Molloy, Smith & Shen (in prep) Kinematics of the disc • The local velocity distribution Famaey et al. (2005) shows a wealth of substructures, which are now being traced beyond the solar-neighbourhood 8

Liu et al. (2012); Molloy, Smith & Shen (in prep) Kinematics of the disc Antoja et al. (2013) • The local velocity distribution Famaey et al. (2005) shows a wealth of substructures, which are now being traced beyond the solar-neighbourhood 8

Liu et al. (2012); Molloy, Smith & Shen (in prep) Kinematics of the disc • The local velocity distribution shows a wealth of substructures, which are now being traced 20 beyond the solar-neighbourhood 80 60 • Recent work has uncovered a 40 RV(km/s) bifurcation in the v R distribution 20 towards the anti-centre 0 − 20 − 40 • What are the causes of this? − 60 Spiral structure, resonances with − 80 spiral or maybe bar? 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 R GC (kpc) • We are now investigating this using the simulation of Juntai Liu et al. (2012) Shen - what are the predictions from a realistic model of the bar? 8

Molloy, Smith & Shen (in prep) Can we see this in simulations? • Take a realisation of the solar neighbourhood, assuming a bar angle of 20 deg. Shen et al. (2010)

Molloy, Smith & Shen (in prep) 20 Can we see this in simulations? 80 60 40 RV(km/s) 20 0 − 20 • Take a realisation of the solar − 40 − 60 neighbourhood, assuming a bar − 80 angle of 20 deg. 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 R GC (kpc) • Does this match the behaviour Solar Neighbourhood Solar Neighbourhood of Liu et al. (2012)? v R (km/s) v R (km/s) R (kpc) R (kpc)

Molloy, Smith & Shen (in prep) 20 Can we see this in simulations? 80 60 40 RV(km/s) 20 0 − 20 • Take a realisation of the solar − 40 − 60 neighbourhood, assuming a bar − 80 angle of 20 deg. 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 R GC (kpc) • Does this match the behaviour Solar Neighbourhood + 90 deg Solar Neighbourhood + 90 deg of Liu et al. (2012)? • What if we look at a random location in the disc? v R (km/s) v R (km/s) R (kpc) R (kpc)

Molloy, Smith & Shen (in prep) 20 Can we see this in simulations? 80 60 40 RV(km/s) 20 0 − 20 • Take a realisation of the solar − 40 − 60 neighbourhood, assuming a bar − 80 angle of 20 deg. 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 R GC (kpc) • Does this match the behaviour Solar Neighbourhood + 180 deg Solar Neighbourhood + 180 deg of Liu et al. (2012)? • What if we look at a random location in the disc? v R (km/s) v R (km/s) • Is this just a statistical fluke? Unlikely, since we see this on both sides of the disc. • What causes this structure... R (kpc) R (kpc)

Molloy, Smith & Shen (in prep) What causes this feature? • Since we have the full orbital history of these stars, we can test whether they are in Solar Neighbourhood resonance with the bar. v R (km/s) R (kpc)

Molloy, Smith & Shen (in prep) What causes this feature? • Since we have the full orbital history of these stars, we can test whether they are in resonance with the bar. • The orbits of stars in a resonance will close in a particular rotating frame y (kpc) x (kpc)

Molloy, Smith & Shen (in prep) What causes this feature? • Since we have the full orbital history of these stars, we can test whether they are in resonance with the bar. Density of closed orbits • The orbits of stars in a resonance will close in a particular rotating frame Ω p (km/s/kpc) R g (kpc)