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The High Redshift Universe Next Door. Josh Simon Carnegie Observatories. Things I Work On. Galaxy kinematics. Dark matter. Milky Way satellites and streams. H II regions/chemical evolution. Dwarf galaxies. Supernovae. Metal-poor stars. Pop Quiz, Hotshot. Is your primary research

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the high redshift universe next door

The High Redshift Universe Next Door

Josh Simon

Carnegie Observatories

things i work on
Things I Work On

Galaxy kinematics

Dark matter

Milky Way satellites and streams

HII regions/chemical evolution

Dwarf galaxies

Supernovae

Metal-poor stars

pop quiz hotshot
Pop Quiz, Hotshot
  • Is your primary research

(a) observational

(b) theoretical

(c) don’t know

If you answered (b) or (c), please skip to the last question

pop quiz hotshot1
Pop Quiz, Hotshot

2. At what wavelengths do you observe?

(a) gamma-ray

(b) X-ray

(c) UV

(d) optical

(e) IR

(f) radio

pop quiz hotshot2
Pop Quiz, Hotshot

3. Are the objects you observe

(a) pretty close (solar system)

(b) far away (Galactic)

(c) really far away (extragalactic)

(d) really, really far away (cosmological)

pop quiz hotshot3
Pop Quiz, Hotshot

4. What is your favorite color?

(a) Red.

(b) Orange.

(c) Green.

(d) Blue. No, yellow!

outline
Outline

I. Formation histories of Local Group dwarfs

a) What were the properties of the first stars and galaxies?

b) What role did the dwarfs play in the buildup of the Milky Way halo?

c) What distinguishes dwarfs from globular clusters?

II. Kinematics of dwarf galaxies

a) What is their dark matter content?

b) What is the nature of dark matter?

a whole new local group

globular clusters

tidal stream

new dwarf

A Whole New Local Group
  • 2011: 27 (!) Milky Way satellite galaxies
    • New dwarfs up to 600 times fainter than any previously known galaxies

(Willman et al., Zucker et al., Belokurov et al.)

Belokurov et al. (2006a)

why study nearby galaxies
Why Study Nearby Galaxies?

Oesch et al. (2009)

Belokurov et al. (2006b)

why study nearby galaxies1
Why Study Nearby Galaxies?

Oesch et al. (2009)

Belokurov et al. (2006b)

1/r2 at z=7: 2  10-59

1/r2 at 100 kpc: 1  10-47

spectroscopic surveys of dwarfs
Spectroscopic Surveys of Dwarfs
  • Metallicity distribution functions
    • Dwarf galaxy evolution and the formation of the halo
  • Chemical abundance patterns as a function of metallicity
  • Search for the most metal-poor stars
    • Nucleosynthesis and chemical evolution in the early universe
spectroscopic surveys of dwarfs1
Spectroscopic Surveys of Dwarfs
  • Gas outflow (and infall) needed to explain MDFs
  • MDFs depend on luminosity

Kirby et al. (2011)

luminosity metallicity relation
Luminosity-Metallicity Relation
  • Faint dwarfs ≠ tidally-stripped bright dwarfs
  • Stars know what luminosity system they live in

Progress needed: How do we match these dwarfs to subhalos in simulations?

Kirby et al. (2011)

universal early chemical evolution
Universal Early Chemical Evolution?

[Mg/Fe]

[Ca/Fe]

MV = -20.5

MV = -11.1

MV = -6.6

MV = -6.3

MV = -5.7

MV = -3.9

MV = -3.8

[Ti/Fe]

[Cr/Fe]

Collaboration opportunity: Compare abundance patterns to high-z Ly-a systems?

Frebel et al. (2010)

Simon et al. (2010)

2000 stars in sculptor1
2000 Stars in Sculptor

[Fe/H] ~ -3.1

[Fe/H] = -3.8

[Fe/H] ~ -3.8

[Fe/H] ~ -3.6

A star?

M dwarf?

the nature of dark matter
The Nature of Dark Matter
  • The missing satellite problem

?

Belokurov et al. (2006a)

Springel et al. (2001)

Progress needed:

(1) More/deeper searches for dwarfs

(2) Larger spectroscopic surveys of kinematics

(3) Understanding observation-simulation comparison

the nature of dark matter1

Ursa Minor

Segue 1

The Nature of Dark Matter
  • Indirect detection of dark matter

Fermi Space Telescope

Strigari et al. (2008)

Martinez et al. (2009)

Simon et al. (2010)

the nature of dark matter2

cusp/core

d(r2)

GM(r)

Jeans equation: r

=

— 

— 2(r)r2

dr

r

The Nature of Dark Matter
  • The density profiles of dark matter halos

1

2

Radial velocities only

Strigari et al. (2007)

the nature of dark matter3

cusp/core

d(r2)

GM(r)

Jeans equation: r

=

— 

— 2(r)r2

dr

r

The Nature of Dark Matter
  • The density profiles of dark matter halos

1

2

GMT/TMT proper motions

Radial velocities only

Strigari et al. (2007)

other projects
Other Projects
  • How are heavy elements distributed through galaxies?
  • What are the progenitors of Type Ia SNe?
  • What is the effect of a low-metallicity environment on star formation and gas tracers?
opportunities for collaboration
Opportunities for Collaboration
  • Observational: stellar kinematics of Local Group dwarfs
  • Theoretical: understanding the matching between real dwarfs and simulated subhalos
  • Theoretical: predictions for observable effects of dark subhalos on tidal streams
new opportunity for students
New Opportunity for Students

http://obs.carnegiescience.edu/gradfellowships

slide25

Summary

  • Local Group dwarfs are unique laboratories for
    • Dark matter - missing satellites, indirect detection, dark matter density profiles
    • Early galaxy formation – first stars, chemical evolution
  • Come talk to me about:
    • Comparisons between observations and N-body simulations
    • Spectroscopic surveys in the Local Group
    • Observational tests of dark matter models
    • Predicted properties of first stars and SNe
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