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

Dynamics of Disk Galaxies Workshop Seoul National University Oct 24th, 2013 Martin C. Smith Shanghai Astronomical Observatory http://hubble.shao.ac.cn/~msmith/

The impact of LAMOST and

• ther major surveys on the

kinematic understanding of the solar neighbourhood

How we can test theories of galaxy formation

Springel et al. (2008)

• LCDM has proved very successful

in terms of large scale structure, 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 simulations on galaxy scales?

• Predictions for the stellar halos are

working well, but the disc is 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

Bullock & Johnston (2005) NGC474

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

Belokurov et al. (2006)

• 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.

• Without doubt the

most prominent survey in the past decade has been SDSS

Progress is driven by large surveys

Juric et al. (2008)

• 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.

• 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

5

Dinescu et al. (1999) Smith et al. (2009)

• Once we have distances we can

investigate the full kinematics, looking at the stellar halo (see also Bond et al., Klement et al, etc)

What have we learnt from SDSS

5

• 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)

What have we learnt from SDSS

5

• 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)

Distance (kpc) z (kpc)

de Jong et al. (2010)

What have we learnt from SDSS

5

• 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)

• However, with full 6D phase-space

we can probe the dynamics

0.5 0.6 0.7 0.8 0.9 1.0 σz/σR 0.0 0.5 1.0 1.5 2.0 |z| (kpc)

[Fe/H] (-0.5, 0.2) (-0.8, -0.5) (-1.5, -0.8)

Smith et al. (2012)

What have we learnt from SDSS

5

• 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)

• However, with full 6D phase-space

we can probe the dynamics

• Although here I am concentrating
• n SDSS, significant contributions

have been made by other surveys, most notably GCS & RAVE

1 2 3 4 z (kpc) 20 40 60 80 100 120 140 Σ (MO

• pc-2)

Visible matter model

Visible + dark matter models M I N N97 OM 1 2 3 4 z (kpc) 20 40 60 80 100 120 140 Σ (MO

• pc-2)

Smith et al. S H M Kuijken & Gilmore Smith et al. (2012)

Dissection with alphas

• Alpha elements are important

tracers of the age of a population

• The daunting task of determining

[α/Fe] for SDSS G-dwarfs was carried out Young-Sun Lee (2011a)

• 1.0
• 0.5

0.0 [Fe/H] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 [α/Fe]

log10 N 1.0 1.5 2.0 2.5

1 . 2 1 . 2 1 . 2 1 . 8 1 . 8 2 . 2.00 2.10

Figure 2.

Lee et al. (2011a)

Dissection with alphas

• Alpha elements are important

tracers of the age of a population

• The daunting task of determining

[α/Fe] for SDSS G-dwarfs was carried out Young-Sun Lee (2011a)

• Old stars behave as expected, but

young stars exhibit opposite trend (see also Loebman et al. 2011, Yu et al. 2012)

• This is a natural consequence of

radial mixing (not migration), with eccentric orbits bringing in stars from the outer- and inner-disc

• 1.0
• 0.5

0.0 [Fe/H] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 [α/Fe]

log10 N 1.0 1.5 2.0 2.5

1 . 2 1 . 2 1 . 2 1 . 8 1.80 2 . 2.00 2 . 1

Figure 2.

140

• 1.0
• 0.5

0.0 [Fe/H] 140 160 180 200 220 240 260 Vφ [km s-1]

Nthin = 8062, ∆Vφ/∆[Fe/H] = -22.6 ± 1.6 Nthick = 5586, ∆Vφ/∆[Fe/H] = +45.8 ± 2.9 0.1 ≤ |Z| < 3.0 kpc

Lee et al. (2011b)

Velocity structure in the outer disc

Kinematics of the disc

8

Liu et al. (2012); Molloy, Smith & Shen (in prep)

• The local velocity distribution

shows a wealth of substructures, which are now being traced beyond the solar-neighbourhood

Famaey et al. (2005)

Kinematics of the disc

8

Liu et al. (2012); Molloy, Smith & Shen (in prep)

• The local velocity distribution

shows a wealth of substructures, which are now being traced beyond the solar-neighbourhood

Famaey et al. (2005) Antoja et al. (2013)

Kinematics of the disc

8

Liu et al. (2012); Molloy, Smith & Shen (in prep)

• The local velocity distribution

shows a wealth of substructures, which are now being traced beyond the solar-neighbourhood

• Recent work has uncovered a

bifurcation in the vR distribution towards the anti-centre

• What are the causes of this?

Spiral structure, resonances with spiral or maybe bar?

• We are now investigating this

using the simulation of Juntai Shen - what are the predictions from a realistic model of the bar?

20 RGC(kpc) RV(km/s) 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 −80 −60 −40 −20 20 40 60 80 Liu et al. (2012)

Molloy, Smith & Shen (in prep)

• Take a realisation of the solar

neighbourhood, assuming a bar angle of 20 deg.

Can we see this in simulations?

Shen et al. (2010)

Molloy, Smith & Shen (in prep)

• Take a realisation of the solar

neighbourhood, assuming a bar angle of 20 deg.

• Does this match the behaviour
• f Liu et al. (2012)?

Can we see this in simulations?

20 RGC(kpc) RV(km/s) 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 −80 −60 −40 −20 20 40 60 80

Solar Neighbourhood

R (kpc) vR (km/s)

Solar Neighbourhood

R (kpc) vR (km/s)

Molloy, Smith & Shen (in prep)

• Take a realisation of the solar

neighbourhood, assuming a bar angle of 20 deg.

• Does this match the behaviour
• f Liu et al. (2012)?
• What if we look at a random

location in the disc?

Can we see this in simulations?

20 RGC(kpc) RV(km/s) 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 −80 −60 −40 −20 20 40 60 80

Solar Neighbourhood + 90 deg

R (kpc) vR (km/s)

Solar Neighbourhood + 90 deg

R (kpc) vR (km/s)

Molloy, Smith & Shen (in prep)

• Take a realisation of the solar

neighbourhood, assuming a bar angle of 20 deg.

• Does this match the behaviour
• f Liu et al. (2012)?
• What if we look at a random

location in the disc?

• Is this just a statistical fluke?

Unlikely, since we see this on both sides of the disc.

• What causes this structure...

Can we see this in simulations?

20 RGC(kpc) RV(km/s) 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 −80 −60 −40 −20 20 40 60 80

Solar Neighbourhood + 180 deg

R (kpc) vR (km/s)

Solar Neighbourhood + 180 deg

R (kpc) vR (km/s)

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. Solar Neighbourhood

R (kpc) vR (km/s)

Molloy, Smith & Shen (in prep) y (kpc) x (kpc)

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

Molloy, Smith & Shen (in prep)

What causes this feature?

Density of closed orbits

Ωp (km/s/kpc) Rg (kpc)

• 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

Molloy, Smith & Shen (in prep)

What causes this feature?

Density of closed orbits

Ωp (km/s/kpc) Rg (kpc)

• 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

• What are we looking at?

Ω = 27 km/s/kpc

−20 −10 10 20 −20 −10 10 20

Ω = 32 km/s/kpc

−20 −10 10 20 −20 −10 10 20

Ω = 46 km/s/kpc

−20 −10 10 20 −20 −10 10 20

Ω = 39 km/s/kpc

−20 −10 10 20 −20 −10 10 20

3:1 2:1 3:2 1:1

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

• What are we looking at?
• It seems they are 3:2
• rbits, in resonance with

the bar - surprising?

Radius (kpc) Pattern Speed (km/s/kpc) Frequency (Myr -1)

Ω = 27 km/s/kpc

−20 −10 10 20 −20 −10 10 20

Ω = 32 km/s/kpc

−20 −10 10 20 −20 −10 10 20

Ω = 46 km/s/kpc

−20 −10 10 20 −20 −10 10 20

Ω = 39 km/s/kpc

−20 −10 10 20 −20 −10 10 20

3:1 2:1 3:2 1:1

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

• What are we looking at?
• It seems they are 3:2
• rbits, in resonance with

the bar - surprising?

• Can they explain the

bifurcation? −150 −100 −50 0 50 100150 10 20 30 40

vR (kpc) Number

LAMOST begins its contribution

The prospects for LAMOST

• Building on the success of SDSS,

China has constructed LAMOST

• This is a 4m telescope with 4000

fibers across a 20 sq deg field of view

• This is a huge undertaking for China,

with no other domestic telescope coming close to this level of complexity

• As with any large project, the early

days are slow, but science results are beginning to emerge

The status of LAMOST

• This is a survey telescope, with

the main focus on the Milky Way

• Aim to collect 5m stars to r<18

in five years, at R = 1,800

• Commissioning has been

completed along with first year

• f full survey, resulting in 2m

stellar spectra

• Large area contiguous survey is

ideal for probing the nature of

• ur galaxy

The status of LAMOST

• This is a survey telescope, with

the main focus on the Milky Way

• Aim to collect 5m stars to r<18

in five years, at R = 1,800

• Commissioning has been

completed along with first year

• f full survey, resulting in 2m

stellar spectra

• Large area contiguous survey is

ideal for probing the nature of

• ur galaxy

100 200 300 RA 10 20 30 40 50 60 Dec

S/N > 10, v_r err < 30 km/s: Total = 15043

18 16 14 12 10 r mag 200 400 600 Num

sigma = 45.1 km/s, mean = −6.79 km/s

−200 −100 100 200 v_r (km/s) 500 1000 1500 2000 Number

Disc populations: M-dwarfs with LAMOST

Zhong et al. (2013)

• M-dwarfs are the dominant class of

stars in our galaxy

• Jing Zhong is working on M-dwarf

classification, in collaboration with Sebastian Lepine

• Using commissioning data they

have a sample of 2,600 M-dwarfs, with distances accurate to ~30%

• Full survey could measure as many

as 100k per year

Disc populations: M-dwarfs with LAMOST

Zhong et al. (2013)

• M-dwarfs are the dominant class of

stars in our galaxy

• Jing Zhong is working on M-dwarf

classification, in collaboration with Sebastian Lepine

• Using commissioning data they

have a sample of 2,600 M-dwarfs, with distances accurate to ~30%

• Full survey could measure as many

as 100k per year

7,000 M-giant candidates LAMOST DR1

A closer look at the disc

• As we have seen, the local

velocity distribution is rich in structures

• Two LAMOST groups are

working on this:

• Qiran Xia has taken a sample
• f FG dwarfs and reconstruct

the underlying distribution

Xia et al. (in prep)

Dehnen (2000)

A closer look at the disc

• As we have seen, the local

velocity distribution is rich in structures

• Two LAMOST groups are

working on this:

• Qiran Xia has taken a sample
• f FG dwarfs and reconstruct

the underlying distribution

• Jingkun Zhao is working on a

similar subject, trying to find moving groups in a sample of thick disc stars

Zhao et al. (in prep)

Conclusions

Summary

• I have shown how current and future surveys are crucial to pushing

forward our knowledge of this field

• SDSS has been highly influential and LAMOST can build on this, by

dramatically increasing the spectroscopic sampling (around 1M stars per year) and by extending to regions avoided by SDSS (e.g. low-latitude)

• Ivezic et al (2008) photometric distance relations have proved to be

very useful (and are crucial to many of the works presented here), but what we really need are Gaia parallaxes

• This is only a brief mention of current and upcoming spectroscopic

surveys, but there are many more such as Gaia-ESO, GALAH, APOGEE, PFS on Subaru, 4MOST, etc, etc....