Scientific Synergy Between
GMT and the SKA
P. McCarthy
GMT
Astronomical Society of Australia Meeting - Perth July 08
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Topics
• Common Science Drivers
• Exoplanets
• Galaxy Evolution
• Dark Energy
• First Light & the Epoch of Reionization
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GMT Science Drivers
Three Approaches:
Discovery Space
Contemporary Science Drivers
Synergy with Current and Future Facilities
Scientific Strengths of the GMT Design:
High angular resolution - 10mas at 1μm
1AU at 100pc - 100 pc at z = 1
Large collecting area - 380 m2 - 10 x Magellan 6.5m
Wide Field - practical paths to seeing-limited survey instruments
Gregorian Adaptive Secondary - GLAO, Great mid-IR performance
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GMT SCIENCE: CONTEXT & SYNERGY
Broad Synergy Across Wavelength,
Spatial and Time Domains
JWST
Physical Diagnostics
Deep/Wide Surveys
High-resolution imaging
High SNR & Res. Spectroscopy
ALMA
LSST
SKA
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Magellan
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SKA Key Science Projects
•
•
•
•
The Cradle of Life
Strong-Field Test of GR
Cosmic Magnetism
Galaxy Evolution & Cosmology
Exoplanets
Black Holes/Pulsars
Galactic/IGM fields
HI in Galaxies
Evolution of Dark Energy
• Probing the Dark Ages
Astronomical Society of Australia Meeting - Perth July 08
Reionization
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GMT Science Goals
• Planets and Their Formation
• Stellar Populations and Chemical Evolution
• Assembly of Galaxies
• Black Holes in the Universe
• The Accelerating Universe
• First Light and Reionization of the Universe
http://www.gmto.org/sciencecase
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GMT Science Goals
• Planets and Their Formation
• Stellar Populations and Chemical Evolution
• Assembly of Galaxies
• Black Holes in the Universe
• The Accelerating Universe
• First Light and Reionization of the Universe
http://www.gmto.org/sciencecase
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Imaging Exoplanets
Exoplanets are faint!…
Jupiter reflects 10-9 Lsun
Earth reflects 10-10 Lsun
…and close in
Jupiter 0.5´´ @ 10pc
Earth 0.1´´ @10pc
Image by David Aguilar, CfA
Suppression of
diffraction is essential
Coronagraphy, phase modulation, nulling, μ-lensing, transits, PRV
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GMT PSF
with phase apodization
1.65 μm, 5% bandwidth
10-6 suppression at 4 λ/D, 56 mas
Young planets are best detected in the 5μm and
10μm bands. There are dozens of young star
clusters visible from Chile and hundreds of
candidate planetary systems.
Typical mass sensitivities:
Age < 100Myr
M < 1Mjup
0.5 Gyr
~2-5 Mj
1.0 Gyr
~5-10 Mj
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10-5 companion
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Internal Structure of Distant Galaxies
|------
1 arcsecond
------|
SKA - 17mas @5Ghz
GMT- 15mas @1.6μm
140mas @591 MHz
150mas with GLAO -8′ fov
Z = 0.1 HST
Hα + Continuum
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Z = 1.4
GMT @1.6μm
1-Hour
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GMT Survey Instruments
IMACS f/2
… maybe not “wide field” by
Australian standards, but large
by ELT standards
GMACS
NIRMOS
GMACS = 10 x Deimos on Keck
18′
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Stellar Populations in Massive Galaxies
Current State of the
Art
Gemini GNIRS
Kreik et al.
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The sky may not be the limit!
Photon counting
Detector + OH
Suppression
OH suppression
Before dispersion
Z = 1.5
Old Galaxy
OH removed in
Post processing
Sky subtracted
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Dark Energy Studies with GMT
•
BAO at z = 5
if w ≠-1 ….. then what?
…….Lyα based BAO study at z = 5 with GMT
cost is high (~100 - 200 nights) but possible
•
SNe spectroscopy at z > 1
SNe Ia at
z=1
•
Identification of LISA sources
Cosmological Distances to ≤ 1%
… may need some help with pre-imaging
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Probing the EOR with GMT & SKA
Key Questions:
- What is “the” redshift
of reionization?
- What is the source(s)
of ionization?
- How does the topology
evolve with redshift?
HI
HII
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N. Gnedin
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Lyα as a probe of the EOR
How can ELTs explore the end of the Dark Ages?
-
Gunn-Peterson effect
-
“Dark” GRBs ?
-
Lyα florescence from boundary regions
-
Evolution of the Lyα luminosity density
-
Spatial correlation between SKA HI maps and LAEs
-
Pencil beam surveys targeted from SKA
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Gunn-Peterson Effect & Reionization Topology
High
τGP
White et al. 2003
High
τGP
11-hour exposures with Keck 10m
Larger aperture needed to sample
more sight-lines
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Reionization History - Double Reionization?
Z=9.4 QSO
Magellan 8hrs
GMT 8hrs
X. Fan
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Lyα Florescence at z ~ 3
QSO
Cont.
At z = 3 all of the HI is in
damped Lyα systems
Lyα abs
Lyα emission
There is a strong case
for florescence at z ~ 3
Adelberger et al. 2005
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Lyα Florescence at the EOR?
FUV
HI
Lyα
Sensitive to
local Jν, xHI
Lyα at z ~ 9
Florescence signal from the
metagalactic flux is faint!
Lyα florescence from bright
QSO is potentially
detectable, if there are
bright sources at the
reionization epoch.
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Visible Halos at z ~ 9
Fully Ionized
25% Neutral
Lyα LF & distribution
provides a probe of
the neutral faction at
high z
Scales are very
large - impractical at
z > 7?
50% Neutral
75% Neutral
Damping wings are
primary escape path
for Lyα photons
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250Mpc = 15 degrees!
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Evolving UV Luminosity Density
Bouwens et al.
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A steep drop off for z > 6.5
could signal the end of the
EOR
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Lyα Luminosity Function at z ~ 6
Ly α luminosity function
from Malhotra & Rhoads
Strong Lensing
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Wide-field NB imaging
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Lyα Luminosity Function at z ~ 6
35 hour integrations
with GMOS on
Gemini S. Faintest
objects have
F = 5E-18.
Stanway et al. 2006.
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Use Case: Lyα Luminosity Function at z ~ 6
500 km/s FWHM
Wλ = 100Å
30hr integration with GMACS
using 0.5” slits in 0.5” seeing
30% throughput
Gemini sky spectrum
Nod & Shuffle sky rejection
R = 5000 rebinned to
R = 1200, Gaussian smoothing
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Mock Lyα Luminosity Function at z ~ 6 with GMT
How do we extend
this to z > 8?
Move to the near-IR,
but fields of view are
smaller, so must
target fields using HI
maps
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IGM Structure at z ~ 9
130 Mpc
“Pencil beam”
surveys can easily
miss the important
structures
SKA can provide the
map needed to
make an informed
survey for Lyα at the
end of the EOR.
~20
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Lyα Spectroscopy in the Near-IR
4Msun/yr
Lyα at z = 8.7
NIRMOS Properties with
current Near-IR detectors
200 km/sec line widths
Photons/sec/cm2
in the J-band
MW Star
formation
rate!
MW Star
formation
rate?
25 hour exposures
7′ x 7′ field of view
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Lyα Spectroscopy in the Near-IR
NIRMOS Properties with OH
Suppression and low-noise
Near-IR detectors
200 km/sec line widths
25 hour exposures
7′ x 7′ field of view
With OH suppression
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Lyα Spectroscopy in the Near-IR
NIRMOS Properties with OH
Suppression and low-noise
Near-IR detectors
200 km/sec line widths
25 hour exposures
7′ x 7′ field of view
With OH suppression
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Structure at z ~ 10
Numerical simulation of gas cooling at z = 10
Dave’, Katz & Weinberg
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Internal Structure in Galaxies at z ~ 10
Ly alpha
image with
GMT GLAO
R=3000 filter
20% escape
fraction for
Lyα
8 hour
exposure
HeII 1640
Lyα
Very top-heavy IMF!
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Laser
Tomography
AO
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Things to take away…..
1. Like SKA, the scientific motivation for GMT is
compelling
2. The two projects are more powerful together than
either is alone
3. Australia can make major contributions to the scientific
and technical development
instruments, adaptive optics, photonics….
Astronomical Society of Australia Meeting - Perth July 08
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