FRIDA's scientific case is broad: it ranges from solar
system bodies to high redshift systems, including pre-stellar cores, circumstelar phenomena in advanced stages of stellar
evolution, the insterestellar medium in the centre of galaxies, thermal vs non thermal emission at high redshift
A number of
scientific challenges for FRIDA are identified here:
High
redshift at kpc scale with FRIDA
FRIDA and
the nearest Universe
FRIDA in
the Milky-Way - sub-parsec scale
High redshift at kpc
scales with FRIDA
- The panoramic view:
FRIDA => Diffraction limit imaging in JHK on 40” x
40“ FoV
- The microscopic view:
FRIDA => 2D spec with <100 mas resolution and a suite
of spectral resolutions
R= 75 km/s
|
=> galaxy dynamics
|
=> Mass
|
R~ 200 km/s (JHK at once)
|
=> Gas diagnosis
|
=> galaxy classification
|
The
challenge for AO-assisted instrumentation at high redshift is to get targets
with a bright star next to it. The figure below shows examples of B-dropouts,
from the HUDF, corresponding to the redshift range 3.5 < z < 4.7
(Beckwith et al. 2006, AJ 132) . Object sizes are typically less than 0.5
arcsec and thus FRIDA spatial scales are ideal for their detailed
spectroscopic study. Unfortunatly, these objects are difficult to observe
with AO instruments due to the lack of a relatively bright star next to
it. Thus, we call the attention of the GTC community on the planning of
current or future surveys, we encourage survey teams looking for
possibilities to explore fields with a relatively bright star, V< 16, in
it so that potential targets for follow up 2D spectroscopy with FRIDA
become possible.
Each image is 1.9 x 1.9
arcsec^2 (13 x 13 kpc at z ~ 4). The FoV of FRIDA at its highest
angular resolution mode is about half of that. The sizes of these objects are
typically < 0.5 arcsec, thus FRIDA spatial scales are ideal for the
detailed spectroscopic study.
FRIDA and the nearest Universe
- The panoramic view:
FRIDA => Diffraction limit imaging in JHK on 40” x
40“ FoV
- The microscopic view:
FRIDA => 2D spec with
40-100 mas resolution and spectral resolution R= 75 km/s
FRIDA spatial resolutions allow us to
study galaxies in the near Universe with unprecedented detail:
FWHM ~ 100 mas =>
|
~ 150 pc @ z=0.05
|
|
FWHM ~ 100 mas =>
|
~ 13 pc @ Virgo
|
=> galaxies across the Hubble sequence
|
FWHM ~ 45 mas =>
|
~ 0.7 pc @ M82
|
=> the nearest starburst
|
FWHM ~ 45 mas =>
|
~ 0.2 pc @ M31
|
=> the nearest spiral
|
As an example, the figure below show
adaptive optics VLT images, in the 1 to 2.5 um range, of the central parsecs
of some of the nearest galaxies in Southern Hemisphere. These galaxies are
part of a international observational program, PARSEC, with VLT and Keck aimed at uncovering the central few
parsecs of the brightest and closest galaxies in the local Universe.
The panels show VLT NACO images of the central parsecs of nearby galaxies. The spatial resolution is ~ FWHM
< 0.1 arcsec. The galaxy nucleus is resolved in two cases: Circinus, ~ 2 pc size at 2 µm (Prieto et al. 2004), and NGC 1068, ~2 x1 pc at 10 µm and at 2 µm (Jaffe et al.
2004, Weigelt et al. 2004)
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Even closer: resolving stars
in Andromeda
Andromeda, the nearest spiral
galaxy to Earth, will be seen with FRIDA down to scales of 1/6 of pc at 2 µm.
At these esolutions, it shall be possible to resolve stars down to the tip of
the RGB and AGB stars, which in Andromeda are brigther than K<18 mag.
Moreover, RGB stars span a wide range of ages, 106 to 109 yr, their detection across Andromeda shall make them suitable candles for:
=> tracing the different stellar
population in the halo, disk, bulge, arms, from which ages could be estimated
and thus, clues on Andromeda history formation be derived.
=> tracing chemical enrichment across the galaxy.
=> kinematics of individual RGB stars => accurate determination of
galaxy potential.
Spitzer view of Andromeda reveals a spiral network of dust filaments at 24 micron in the disk. FRIDA will be able to see through this dust to explore the dynamic of multutud of proto star clusters forming behind this dust. FRIDA will attain a resolution 25 times superior than Spitzer, 1.6 superior than JWST. It will resolve Androemda at 1/10 of parsec in J-band, at 1/6 of parsec in K-band.
The figure shows a
synthetic color-magnitude diagram (CMD) generated for a stellar population
located at M31's distance (Marin-Franch, 2007). It can be seen that the tip
of the RGB is brighter then K=18.
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FRIDA in the Milky Way - sub parsec
- The panoramic view:
FRIDA => Diffraction limit imaging in JHK on 40” x 40“
FoV
- The microscopic view:
FRIDA => 2D spec
with 45 mas resolution and spectral resolution down to R= 10 km /s
FRIDA will allow us both,
parsec-scale studies of a large number of galactic sources
(HII regions, HH objects, binaries, planetary nebulae, stellar disks …)
but also accurate spectral diagnosis of many of these sources (stellar
atmospheres, metalicities, ages) thanks to its very high spectral
resolution. The figure below illustrates the case of ultra compact HII
regions. These are very dusty regions where massive stars come to light. The
new born stars are embedded in their parental cloud and therefore the
mechanisms by which star formation sparks can only be explored in the IR.
Left panel is an optical view of
the compact HII region G61.48+0.09, the right panel shows the same region in the IR with the AO system ALPHA at the Calar Alto
observatory. The IR -AO uncovers many hidden
stars, among which the brightest, K=9 mag star, is thought to be
the lionizing source of the HII region (Puga et al. 2004). FRIDA will provide similar images but
with the add-on of a very accurate spectral characterization of the
sources with resolution of 10 km/s.
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