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The Submillimeter Array
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David J. Wilner
[email protected]
What is the Submillimeter Array?
The SMA is an exploratory instrument comprised of eight moveable
6 meter antennas designed for high spatial and spectral resolution
imaging through semi-transparent submillimeter atmospheric windows.
The SMA is a collaborative project of the Smithsonian Astrophysical Observatory, part of the Harvard-Smithsonian Center for
Astrophysics, and the Academia Sinica Institute of Astronomy and Astrophysics (Taiwan)
Why “Submillimeter” ?
best part of electromagnetic
spectrum to study “cool” material
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Why a Submillimeter “Array” ?
• resolution ~ /D:
1 arcsec at  = 1 mm
requires D = 200 meters!
• interferometry: combine
signals from separate
small telescopes to
synthesize a large one
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Submillimeter Array Science
• a unique and versatile telescope
– Solar System bodies, protoplanetary disks, star forming
regions, evolved star envelopes, black holes, nearby galaxies,
ultraluminous galaxies at cosmological distances, …
• in very high demand
– more than 200 observing proposals per year
– fewer than 1 out of 4 of submm requests accommodated
– archive: data in public domain after 15 months
• more than 200 papers in refereed journals
– more than 1000 authors and co-authors
– PhDs: Harvard, SAO predocs, Hawaii, Taiwan, …
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Submillimeter Array Operations
• dynamic queue scheduling according to weather
• primary observations from Mauna Kea, remote from Hilo base
facility, Cambridge, Taipei
• SMAOC web portal for both operations and PIs to track projects
from proposal through observations with up-to-minute information
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SMA Science Examples
Debris on Jupiter
SgrA* Black Hole
Planet Forming Disks
Distant Galaxies
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Cometary Debris on Jupiter
• comet SL-9 impact in
1994 deposited material
in Jovian atmosphere,
fading over time
SMA HCN J=3-2
• SMA images distribution
of molecules, e.g. HCN
• fate: downward transport
at poles dominates
photo-chemical evolution
Moreno et al., 2010
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Planet Forming Disks
• images of dust and gas around ~1 Myr
old stars at scale of our Solar System
• initial conditions for planet building
• significant fraction show inner holes:
evidence for giant planets in formation
NASA/JPL/T. Pyle (SSC)
Andrews et al. 2010
Hughes et al. 2009
Brown et al. 2007, 2009
Early Universe Starbursts
• half of luminous cosmic
energy density comes from
dust enshrouded sources
• SMA observations locate
dusty sources to <0.2 arcsec,
enable multi- assessment
• population of galaxies with
extreme star formation
when Universe was <20%
of current age, invisible to
Hubble Space Telescope
Younger et al. 2007, 2009, 2010
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Closest Look at a Black Hole
• SgrA* at Galactic Center,
4 million times mass of Sun,
largest black hole on the sky
• Earth-size mm telescope!
Hawaii-California-Arizona
(SMA/JCMT-CARMA-SMT)
– 37 arcsec scale emission
size of event horizon
– hot spot in accretion flow?
• higher sensitivity planned to
access time variable structure
Doelman et al. 2008
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SMA Outreach
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