Download Future Directions for Astronomy at MSU The lab The rest

Future Directions for Astronomy
at MSU
The lab
The rest
of the lab
The connection to JINA
Pepperoni
Evolution
• of structure
Cheese
stars
Cell-like arrangement of
galaxies in the local Universe
galaxies
(de Lapparent, Geller & Huchra 1986)
galaxy clusters
• Chemical evolution
The SOAR Telescope
Jan. 2004
Jan. 2004
Dedication:
April 17, 2004
Nov. 2003
Initial Instrument Complement
Exploit high image quality over widest
possible FOV
IR imager
MSU
IR spectrographs
NOAO
Optical imager
NOAO
High-throughput optical spectro.
UNC
The Spartan
IFU optical spectrograph
Brazil
Infrared
Camera
2nd Generation Instruments:
• Optical echelle spectrograph
• Optical adaptive optics system
Brazil
NOAO (+MSU?)
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?
Galactic structure and stellar
astronomy
Tim Beers
Bob
Stein
Ed
Brown
Horace
Smith
Astronomical
Instrumentation.
Ed Loh
Gene
Capriotti
Extragalactic
Astronomy
Steve
Zepf
Jack
Baldwin
Megan
Donahue
Mark
Voit
What is the Universe
made of?
We know these are there,
but we don’t know what
they are.
• 73% Dark Energy
• 22% Dark Matter
• 4% Normal Matter
(using E = mc2)
This is the only part we see.
Dark Energy
Dust
Reiss et al. 2001
0
0.2
0.4
0.6
Redshift z
0.8
No Dust
Accelerating
Evolving
Universe.
0.75
mag
-2.5 log flux
Scale factor R(t) 
Measured using
Type Ia supernovae as “standard candles”
0.5
0.25
0
-0.25
-0.5
-0.7
5
0
+ (0.2,0)
No evolution
(0.2,0.8)
(0.2,0)
(1,0)
0.5
1
1.5
2
2.5
z
Now
Flux difference
as function
of z
Time

1.0
Ed Loh + collaborators (Baldwin, Donahue, Zepf)
No evolution
Evolving
2.5
•
2
N(<z)
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.
(M,) = (0.3,0.7)
1.5
(0.3,0)
1
(1,0)
0.5
0
0
0.5 1
1.5 2
z
2.5
Number per 4 hr SOAR exposure
Dark Energy “Equation of State”
pressure
• P- relation is unknown
• Results usually shown assuming P = -
energy density
– “Cosmological constant”
P = -
P = -0.726
• But poorly constrained.
• Can be measured using high-precision SN
observations.
– Proposed SNAP satellite project?
– But meanwhile, can make progress with SOAR
+ larger telescopes
P = -R(t)
Dicus & Repko
2003:
Goodness of fit
contours for various
equations of state.
Steve Zepf:
Looking back to the time of galaxy
formation
Bottom-up structure formation.
• Huge light-travel times  we can see galaxies
being assembled from smaller units, over 13
billion years ago.
Rate at which stars
are formed in
galaxies.
Jack Baldwin:
Use quasars to trace
early history of metal
enrichment in massive
galaxies
Number of
Quasars per unit
volume
Now
= 14 billion yrs
 time
Quasars are
events in young
galaxies.
Formation of
universe
Measure CNO abundance
in gas falling into active
galactic nucleus:
Steve Zepf
The 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
Megan Donahue & Mark Voit:
Giant galaxy clusters
• 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
Hercules Cluster
Galactic structure and stellar
astronomy
Tim Beers
Bob
Stein
Ed
Brown
Horace
Smith
Gene
Capriotti
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
Large Magellanic Cloud
M31, M32,
NGC 205
Tim Beers
The “First Star”: HE 0107-5240
(+ Brian Marsteller, Ankur Warikoo)
[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.
Wavelength 
Galactic orbital
velocity components
vs. [Fe/H]
• 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.
[Fe/H]
distributions
in the MK and
HES surveys
Tim Beers
• SOAR medium resolution spectroscopy:
– Candidate giants with [Fe/H] < -2.5
Cooler, Ultra Metal-Poor
[Fe/H] = -3.60
[C/Fe] = +1.87
• 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.
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
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
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
What we study
• Dark energy
– Type Ia supernovae
– Galaxy clusters
• Dark matter
Astronomy
– Evolution of structures
• Galaxies
• Galaxy clusters
High Energy
Physics
• Chemical evolution
– Stellar processes
– Chemical abundances
in stars
– Evolution of stellar
populations
Nuclear
Physics
REF proposal: Center for the Study of Cosmic Evolution
Scale factor R(t) 
“Dark Energy”
• Dark energy was discovered by
measuring distant supernovae.
Accelerating
Universe.
Now
Time 
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?
Some Hypotheses
– SNe do not evolve &
(M,) = (0.2,0.8)
– SNe do not evolve, but
are dimmed by “grey”
dust.
– SNe evolve so that
dL/L  1/time
2
No Dust
Evolving
(M,) = (0.3,0.7)
1.5
(0.3,0)
1
(1,0)
0.5
0
(0.2,0)
+ evolution
mag
N(<z)
Reiss et al. 2001
No evolution
2.5
Dust
0
0.5
1
z
1.5
2
2.5
Number of SNe per 4 hr SOAR exposure
0.75
0.5
0.25
0
-0.25
-0.5
-0.75
(0.2,8)
(0.2,0)
(1,0)
0
0.5
1
1.5
2
2.5
z
Flux difference as function of z