Transcript ALMA - ESO

Science With ALMA
T. L. Wilson
European ALMA Project Scientist,
and
Interim JAO Project Scientist
ESO Seminar, 25 May 2006
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Bilateral ALMA + ALMA Compact Array (in lower right)
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Location
ALMA
Chajntantor
Plateau at
5000m in
northern Chile
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ALMA Science Drivers
Key drivers:
Detect the Milky Way at z=3
Measure dust broadband emission and spectral line radiation
from atoms and molecules in high-z galaxies to obtain
detailed morphology and kinematics
Protostars and planet formation:
Angular resolution of an AU at 150 pc (nearest molecular cloud);
10milli arc seconds
High Fidelity Images in Spectral Lines and Continuum
ESO Seminar, 25 May 2006
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Simulation of a protostellar disk
150
Light
years
300
Light
years
Jupiter-mass protoplanet around 0.5
solar mass star
Orbital radius: 5 AU
Maximum baseline: 10 km
f = 850 GHz
8 hour integration
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Sizes of the SPIRE and PACS beam sizes on the HDF north Field
This
shows the
limits of
Herschel
angular
resolution.
Herschel
measurements
need
follow ups
with higher
angular
resolution
imaging
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UV
Visible
Infrared
mm
Intensity
Add dust
Wavelength
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A Next Generation Millimeter Telescope
A major step in astronomy  a mm/submm equivalent of VLT, HST, JWST, EVLA
Capable of seeing star-forming galaxies across the Universe
Capable of seeing star-forming regions across the Galaxy
These Objectives Require:
An angular resolution of 0.1” at 3 mm
A collecting area of about 6,000 sq m
An array of antennas to obtain arc sec or better angular resolution
A site which is high, dry, large, flat since water vapor absorbs mm/sub-mm
signals
A high Andean plateau is ideal
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Summary of Requirements
Frequency
30 to 950 GHz (initially only 84-720 GHz)
Bandwidth
8 GHz, fully tunable
Spectral resolution
3.15 kHz (0.01 km/s) at 100 GHz
Angular resolution
1.4” to 0.015” at 300 GHz
Dynamic range
10000:1 (spectral); 50000:1 (imaging)
Flux sensitivity
0.2 mJy in 1 min at 345 GHz (median conditions)
Bilateral Antenna Complement 50 to 64 antennas of 12-m diameter
ACA
12 x 7-m & 4 x 12-m diameter antennas
Polarization
All cross products
ESO Seminar,simultaneously
25 May 2006
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Back End & Correlator
Technical
Building
ANTENNA
Correlator
Front-End
Tunable Filter Bank
IF-Processing
(8 * 2-4GHz sub-bands)
Digitizer
8* 4Gs/s -3bit ADC
8* 250 MHz, 48bit out
Local
Oscillator
Digital De-Formatter
Digitizer
Clock
Optical De-Mux
& Amplifier
Data Encoder
12*10Gb/s
12 Optical Transmitters
12->1 DWD Optical Mux
Fiber
ESO Seminar, 25 May 2006
Fiber Patch-Panel
From 270 stations to
64 DTS Inputs
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Correlator Set Up: Four IF Bands of 2 GHz Each Can be Analyzed by
32 Filters, 16 in Each Polarization
Region analyzed by a single spectrometer
(we show ½ of
the filters)
2 GHz wide IF
Spectrometer is a recycling correlator:
# of channels x total bandwidth=(128)x(2 GHz)
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The ALMA
FOV is 25”
at 1 mm
ALMA
Receiver
Bands
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Sensitivity
with 6
antennas
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Bands 3, 6, 7 and 9 are in bilateral ALMA
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Herschel and ALMA Science: The Cool Universe
Herschel is best suited for surveys, ALMA a followup instrument
ALMA has a small Field Of View (FOV), but high angular
resolution and sensitivity
Higher angular resolution to image the sources measured by
Herschel
Follow up to sources discovered with PACS or SPIRE in
longer wavelength dust emission
Also, surveys in CO to determine redshifts
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Herschel and ALMA Science Topics
ISM in Galaxies:
• Normal galaxies
• Physical properties
of star-forming ISM
ISM in the
Milky Way:
Dense cores and
star-formation:
• Structure
• Dynamics (pressure)
• Composition
(gradients)
• Temperature, density
structure
• Dust properties
• Stellar IMF
Late stages of
stellar
evolution:
Solar System:
• Water in Giant Planets
• Atmospheric
chemistry
• Water activity and
composition of comets
• Winds
• Shells
• Asymmetries
• Composition
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Scientific Areas
High Redshift Galaxies and Cosmology
Active Galactic Nuclei & Star Formation in Galaxies
Star and Planet Formation
Water in the Universe
Astrochemistry in Hot Cores and Envelopes of Evolved
Stars
Solar System
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High Redshift Sources and AGN’s
High star formation rates, >>20 solar masses per year
Most of the radiation emitted by stars is absorbed by
dust and re-radiated in the 3 micrometer to 1 mm
wavelength range
The luminous IR galaxies trace regions where the
concentration of galaxies is largest, and trace the
formation of large scale structures.
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AGN’s: Herschel & ALMA
Measure 1000’s of sources with PACS and SPIRE, then follow
up with longer wavelength continuum data with ALMA
ALMA spectral line measurements of CO and other species
Herschel will sample the regime where most of the luminosity is
radiated
High resolution images with ALMA allow a better determination of the size
of emission sources ALMA would provide high resolution images to refine
models.
Separate star formation and accretion in AGN’s
Could also make imaging survey of sources found with PLANCK
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Image of the redshift z=6.4 source in CO
line emission
The
CO emission
was shown to be
extended
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CO Lines Observable with ALMA Receivers as a Function of Redshift
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Normalized integrated CO line intensity
With a
number of
CO line
measurements
one can determine
physical
parameters
of a source
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NGC6240-An AGN Case Study
NICMOS 1.6 micron
CO J=2-1
0.7” resolution
IRAM Interferometer
2”, 960 pc
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Nearby Galaxies
Investigate star formation in other types of galaxies
At 10 Mpc, 0.1” is equivalent to 4.8 pc
Compare to models, in regard to the influence of nearby
surroundings, metallicity, mergers
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IC10-A Nearby Blue Dwarf Galaxy
D=0.7 Mpc;
Total size
of the
image is 10’
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Boxes
show
FOV
of
Bolometers.
The FOV
of ALMA
at 3 mm
is the
circle
in the
lower
left
Smallest
box is
the integral
field
spectrometer
In PACS
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Star Formation in our Galaxy
We can study different stages of star formation in
individual sources
We believe that the basic physical laws are understood
but the relative importance of various effects is not
known
The study of low mass star formation will allow us to
understand how our solar system formed
In this study we group ‘protostars’ and ‘debris disks’
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Sketch of Protostar Development
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450/850 micrometer
images of Fomalhaut.
The contours are
13 and 2 mJy/beam.
Below are
deconvolved
images (data from
JCMT and SCUBA)
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Dust Spectra and Herschel Bolometer Bands
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Orion KL Spectrum from Ground
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Orion KL: The Classical Hot Core Source
Within a
20” region
there are
a variety
of physical
conditions
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Heerschel HIFI Water Lines
This
transition
in
ALMA
band 5
(a maser
line)
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Main Sequence & Evolved Stars
In broadband continuum, ALMA should be able to detect
high mass stars in our Galaxy, and evolved stars even
in the LMC
In evolved stars such as IRC+10216, ALMA will be able
to image molecular and dust emission
Herschel can be used to search for water vapor in the
envelopes of such stars
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Sample
spectra
from
IRC+10216
(R Leo),
a nearby
carbon
star
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Images of some
molecules
in IRC10216,
a nearby
carbon star
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Solar System Objects
Herschel can easily measure outer planets, and moons
of these planets, as well as Trans Neptune Objects
Highly accurate photometry
Water on the giant planets
Follow up would be HDO, to determine D/H ratio
ALMA and Herschel might be used to measure a
common source at a common wavelength to set up a
system of amplitude calibrators
ALMA provides high resolution image, but also records the
total flux density
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A Comparison of
analysis schemes
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Conclusions
Overall, Herschel is best suited for surveys, while ALMA a follow
up instrument
ALMA has a small FOV, but high angular resolution and sensitivity
Higher angular resolution to image the sources measured or detected by
Herschel
Also follow ups to PACS or SPIRE surveys in CO or in longer wavelength
dust emission
Need common set of sources
In combining results we need well established calibrations
In analyzing the results, really need a much more sophisticated
system
For planets, comets and asteroids can image in spectral lines
and continuum
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