Future Directions for Astronomy at MSU

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Future Directions for Astronomy at MSU
The lab
The rest of the lab
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The connection to JINA
7x108 ly
Cell-like arrangement of galaxies in the local
Universe (de Lapparent, Geller Huchra 1986)
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The SOAR Telescope
Dedication April 17, 2004
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Initial Instrument ComplementExploit high image
quality over widest possible FOV

• IR imager MSU
• IR spectrographs NOAO
• Optical imager NOAO
• High-throughput optical spectro. UNC
• IFU optical spectrograph Brazil

• 2nd Generation Instruments
• Optical echelle spectrograph Brazil
• Optical adaptive optics system NOAO (MSU?)

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Adaptive Optics

• Fast wavefront sensor detects distortions due to
  atmospheric seeing.
• Rubber mirror corrects wavefront.
• Natural guide star systems are operational, but
  low sky coverage.
• Need laser guide stars for high science
  productivity.

?MSU?
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Galactic structure and stellar astronomy
Tim Beers
Bob Stein
Ed Brown
Horace Smith
Gene Capriotti
Extragalactic Astronomy
Megan Donahue
Steve Zepf
Mark Voit
Jack Baldwin
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What is the Universe made of?

• 73 Dark Energy (using E mc2)
• 22 Dark Matter
• 4 Normal Matter

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Dark Energy Measured using Type Ia supernovae
as standard candles
-2.5 log flux
0 0.2 0.4 0.6 0.8
1.0 Redshift z

• Ed Loh collaborators (Baldwin, Donahue, Zepf)
• Use Spartan Infrared Camera on SOAR to measure
  SNe at greater distances.
• Are SNe really reliable standard candles?
• Dimming by dust?
• Luminosity evolves with lookback time?
• use dL/L ? 1/time as strawman.

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Dark Energy Equation of State
pressure

• P-? relation is unknown
• Results usually shown assuming P -?
• Cosmological constant
• But poorly constrained.
• Can be measured using high-precision SN
  observations.
• Proposed SNAP satellite project?
• But meanwhile, can make progress with SOAR
  larger telescopes

energy density
Dicus Repko 2003 Goodness of fit contours for
various equations of state.
P -?
P -R(t)?
P -0.726?
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Looking back to the time of galaxy formation
Steve Zepf

• Bottom-up structure formation.
• Huge light-travel times ? we can see galaxies
  being assembled from smaller units, over 13
  billion years ago.

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Jack BaldwinUse quasars to trace early history
of metal enrichment in massive galaxies
Rate at which stars are formed in galaxies.
Number of Quasars per unit volume
Formation of universe
? time
Now 14 billion yrs
Quasars are events in young galaxies.
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Steve ZepfThe History of Galaxy Assembly
Galaxies trace the evolution of structure in
the universe. Galaxies are where star and
planet formation occurs.
Use globular clusters to reconstruct the
formation history of nearby galaxies of all types
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Megan Donahue Mark Voit Giant galaxy clusters
Hercules Cluster

• Recently formed ? test details of bottom-up
  formation scenario.
• Evolution of cluster population
  ? sensitive probe of dark matter and dark energy
• Best fair sample of matter content of Universe
• Dark vs. normal matter

Gravitational lensing measures total mass of
foreground cluster
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Galactic structure and stellar astronomy
Tim Beers
Bob Stein
Ed Brown
Horace Smith
Gene Capriotti
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The History of our own Galaxy.Star-by-star
archeology.

• Growth of galaxies by accretion.
• Chemical evolution.
• all elements heavier than H and He were formed
  by nuclear reactions in stars.

Small Magellanic Cloud
Milky Way
M31, M32, NGC 205
Large Magellanic Cloud
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Tim Beers ( Brian Marsteller, Ankur Warikoo)
The First Star HE 0107-5240 Fe/H
-5.3 C/Fe 3.9 N/Fe 2.4
Chemical abundances in oldest 2nd generation
stars.

• Long-lived stars from just after initial round of
  star formation.
• Found by searches through huge samples.
• SOAR optical imager for
• Metallicity distribution of halo stars.
• Kinematics of thick disk and
  halo populations.
• Distance to high velocity H I clouds in galactic
  halo.

Wavelength ?
Galactic orbital velocity components vs. Fe/H
Fe/H distributions in the MK and HES surveys
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Tim Beers

• SOAR medium resolution spectroscopy
• Candidate giants with Fe/H lt -2.5
• for follow-up with 8m-class telescopes.
• find additional r-process enhanced stars.
• Carbon-enhanced stars
• Candidates for high-resolution abundance
  analyses.
• likely to have s-process enhancement.
• Study C and N abundances.

Cooler, Ultra Metal-Poor Fe/H -3.60
C/Fe 1.87

Warmer, Slightly Metal-Poor Fe/H -1.04
C/Fe 0.24

• SOAR high-resolution spectrocopy
• Carbon-enhanced binary stars
• Find through long-term monitoring of radial
  velocity variations
• orbital properties ? mass ratios, mass transfer
  mechanisms, stellar evolution
• observe during twilight at beginning and end of
  nights.
• Elemental abundances for metal-poor stars
  brighter than B 14.5

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Horace Smith Variable stars

• Keys to distance scale.
• Determining size of universe depends on local
  distance scale.
• Laboratories for stellar evolution.
• Pulsation properties probe inner structure of
  stars.
• Probes of galactic structure and history
• Easily identified by brightness changes

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With SOAR, Variable Stars can be studied in
detail throughout the Local Group
Large Magellanic Cloud
and in the bulge of the Milky Way.
The galactic bulge includes many globular clusters
NGC 6822
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What we study

• Dark energy
• Type Ia supernovae
• Galaxy clusters
• Dark matter
• Evolution of structures
• Galaxies
• Galaxy clusters
• Chemical evolution
• Stellar processes
• Chemical abundances in stars
• Evolution of stellar populations

REF proposal Center for the Study of Cosmic
Evolution
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Dark Energy

• Dark energy was discovered by measuring distant
  supernovae.

• Ed Loh collaborators (Baldwin, Donahue, Zepf)
• Use Spartan Infrared Camera on SOAR to measure
  SNe at greater distances.
• Are SNe really reliable standard candles?
• Was Dark Energy constant throughout time?

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Some Hypotheses
Dust

• SNe do not evolve (?M,?L) (0.2,0.8)
• SNe do not evolve, but are dimmed by grey dust.
• SNe evolve so that dL/L ? 1/time

Reiss et al. 2001
No Dust
(0.2,0) evolution
No evolution
Evolving
(?M,??) (0.3,0.7)
(0.2,8)
g
a
(0.3,0)
(0.2,0)
m
?
(1,0)
(1,0)
z
Flux difference as function of z
Number of SNe per 4 hr SOAR exposure