ESO Seminar, 25 May 20061 Science With ALMA T. L. Wilson European ALMA Project Scientist, and Interim JAO Project Scientist

ESO Seminar, 25 May 2006 1

Science With ALMA

T. L. WilsonEuropean ALMA Project Scientist,

and

Interim JAO Project Scientist


Bilateral ALMA + ALMA Compact Array (in lower right)


ALMALocation

Chajntantor Plateau at5000m in northern Chile


ALMA Science DriversKey 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


Simulation of a protostellar disk

Jupiter-mass protoplanet around 0.5 solar mass star Orbital radius: 5 AU

Maximum baseline: 10 kmf = 850 GHz8 hour integration

150 Light years

300Light years


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


Visible Infrared mmUV

Wavelength

Inte

nsit

y

Add dust


A Next Generation Millimeter Telescope

A major step in astronomy a mm/submm equivalent of VLT, HST, JWST, EVLACapable of seeing star-forming galaxies across the UniverseCapable of seeing star-forming regions across the Galaxy

These Objectives Require:An angular resolution of 0.1” at 3 mmA collecting area of about 6,000 sq mAn array of antennas to obtain arc sec or better angular resolutionA site which is high, dry, large, flat since water vapor absorbs mm/sub-mm signals

A high Andean plateau is ideal


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 simultaneously


Back End & Correlator

Front-End

DigitizerClock

Local Oscillator

ANTENNA

Data Encoder12*10Gb/s

12 Optical Transmitters

12->1 DWD Optical Mux

Digitizer8* 4Gs/s -3bit ADC

8* 250 MHz, 48bit out

IF-Processing(8 * 2-4GHz sub-bands)

Fiber Patch-PanelFrom 270 stations to 64 DTS Inputs

Optical De-Mux& Amplifier

Digital De-Formatter

Correlator

Technical Building

Tunable Filter Bank

Fiber


Correlator Set Up: Four IF Bands of 2 GHz Each Can be Analyzed by 32 Filters, 16 in Each Polarization

2 GHz wide IF

Region analyzed by a single spectrometer

Spectrometer is a recycling correlator: # of channels x total bandwidth=(128)x(2 GHz)

(we show ½ of the filters)


The ALMAFOV is 25”at 1 mm

ALMA ReceiverBands


Sensitivity

with 6

antennas

Bands 3, 6, 7 and 9 are in bilateral ALMA


Herschel and ALMA Science: The Cool Universe

Herschel is best suited for surveys, ALMA a follow-up instrument

ALMA has a small Field Of View (FOV), but high angular resolution and sensitivityHigher angular resolution to image the sources measured by HerschelFollow up to sources discovered with PACS or SPIRE in longer wavelength dust emission Also, surveys in CO to determine redshifts


Herschel and ALMA Science Topics

Solar System:• Water in Giant Planets• Atmospheric chemistry• Water activity and composition of comets

ISM in Galaxies:• Normal galaxies• Physical properties of star-forming ISM

Dense cores and star-formation:• Temperature, density

structure• Dust properties• Stellar IMF

ISM in the Milky Way:• Structure• Dynamics (pressure)• Composition (gradients)

Late stages of stellar evolution:• Winds• Shells• Asymmetries• Composition


Scientific Areas

High Redshift Galaxies and CosmologyActive Galactic Nuclei & Star Formation in GalaxiesStar and Planet FormationWater in the UniverseAstrochemistry in Hot Cores and Envelopes of Evolved StarsSolar System


High Redshift Sources and AGN’s

High star formation rates, >>20 solar masses per yearMost of the radiation emitted by stars is absorbed by dust and re-radiated in the 3 micrometer to 1 mm wavelength rangeThe luminous IR galaxies trace regions where the concentration of galaxies is largest, and trace the formation of large scale structures.


AGN’s: Herschel & ALMAMeasure 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


Image of the redshift z=6.4 source in CO line emission

The CO emissionwas shown to beextended


CO Lines Observable with ALMA Receivers as a Function of Redshift


Normalized integrated CO line intensity

With a number of CO linemeasurementsone can determinephysical parametersof a source


NGC6240-An AGN Case Study

NICMOS 1.6 micronNICMOS 1.6 micron

CO J=2-10.7” resolutionIRAM Interferometer

2”, 960 pc


2”, 960 pc


2”, 960 pc


Nearby Galaxies

Investigate star formation in other types of galaxiesAt 10 Mpc, 0.1” is equivalent to 4.8 pc

Compare to models, in regard to the influence of nearby surroundings, metallicity, mergers


IC10-A Nearby Blue Dwarf Galaxy

D=0.7 Mpc;

Total size of the image is 10’


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


Star Formation in our Galaxy

We can study different stages of star formation in individual sourcesWe believe that the basic physical laws are understood but the relative importance of various effects is not knownThe study of low mass star formation will allow us to understand how our solar system formedIn this study we group ‘protostars’ and ‘debris disks’


Sketch of Protostar Development


450/850 micrometerimages of Fomalhaut.The contours are13 and 2 mJy/beam. Below are deconvolvedimages (data from JCMT and SCUBA)


Dust Spectra and Herschel Bolometer Bands


Orion KL Spectrum from Ground


Orion KL: The Classical Hot Core Source

Within a

20” region

there are

a variety

of physical

conditions


Heerschel HIFI Water Lines

This transition inALMA band 5 (a maser line)


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 LMCIn 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


Sample spectra from IRC+10216(R Leo), a nearbycarbonstar


Images of some molecules in IRC10216, a nearby carbon star


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 planetsFollow 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


A Comparison of

analysis schemes


Conclusions

Overall, Herschel is best suited for surveys, while ALMA a follow up instrument

ALMA has a small FOV, but high angular resolution and sensitivityHigher angular resolution to image the sources measured or detected by HerschelAlso follow ups to PACS or SPIRE surveys in CO or in longer wavelength dust emission

Need common set of sourcesIn 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

Documents

ESO Seminar, 25 May 20061 Science With ALMA T. L. Wilson European ALMA Project Scientist, and Interim JAO Project Scientist