Submillimeter Astronomy in Taiwan
Submillimeter Astronomy in Taiwan
Academia Sinica Institute of Astronomy and Astrophysics, Taipei, Taiwan
1. INTRODUCTION is 509 m, providing an angular resolution
Submillimeter astronomy in Taiwan was of 0.1” at 690 GHz. Fig. 1 shows a picture
dramatically developed in the last 15 years. of the SMA.
The development was initiated at ASIAA
by joining the Berkeley-Illinois-Maryland While the initial SAO concept for the
Association millimeterwave interferom- SMA was six 6-m antennas, in 1996
eter (BIMA) project in 1993 in order to ASIAA joined the SMA project by agree-
educate young staff members and students ing to add two more antennas and all the
working at ASIAA for radio astronomy. associated electronics, including a dou-
The emphasis was on interferometric bling of the correlator and additional re-
technique, which is the key to achieve ceiver systems. The additional two anten- Nagayoshi Ohashi
high angular resolutions at millimeter nas increased the number of instantaneous
and submillimeter wavelengths. While the baselines from 15 to 28, nearly doubling
participation in the BIMA project focused the mapping speed of the array. and the SMA was formally dedicated on
on producing good radio astronomers 2003 November 22. More details of the
as “users,” ASIAA also recognized the The Academia Sinica funded the expan- SMA are found in Ref. 1.
importance of technical development for sion of the SMA as the first astronomical
radio astronomy. The Submillimeter Ar- project at the ASIAA. Collaborating with 2.1. Science with the SMA
ray (SMA) project was identified as the the Aeronautical Research Laboratory The SMA is a multi-purpose telescope,
first astronomical project associated with (ARL), ASIAA delivered two SMA tele- which allows us to conduct research on a
significant technical development. The scopes. In the newly established receiver variety of astronomical subjects. Major re-
participation in the SMA project has been lab, the associated receiver system and search areas include Solar system, Galactic
of great help for ASIAA not only in devel- electronics were constructed. By the end star formation, nearby galaxies, AGNs, ul-
oping a strong submillimeter astronomy of 2003, all eight antennas of the array had tra luminous galaxies, high-Z galaxies, and
group at ASIAA, but also in establishing a been deployed on the top of Mauna Kea, astrochemistry. Although it is impossible to
receiver laboratory at ASIAA and in devel-
oping good partnerships with the industry
in Taiwan. The SMA project also helped
to diffuse submillimeter astronomy among
universities in Taiwan. These successful
developments were followed by the Tai-
wanese participation in the Atacama Large
Millimeter/submillimeter Array Project.
2. SUBMILLIMETER ARRAY
The SMA, a collaborative project of
ASIAA and the Smithsonian Astrophysi-
cal Observatory (SAO), consists of eight
6-m radio telescopes constructed at the
top of Mauna Kea, Hawaii. It covers the
frequency range of 180 GHz to 950 GHz,
although receivers above 700 GHz are still
under development. The longest baseline Fig. 1: Photograph of the SMA at Mauna Kea, Hawaii.
AAPPS Bulletin October 2009, Vol. 19, No. 5 11
Astronomy in Taiwan
Fig. 2: (Left-hand panels): SMA images of the SiO (8-7) outflow in the HH211 system. The red- and blue-shifted parts of the outflow show a
clumpy and wiggling structure along the jet. The green contours mark the dust emission from the central disk which surrounds the exciting source.
(Right-hand panels): Velocity structures of the innermost blue-shifted lobe (BK1) and red-shifted lobe (RK1). Blue and red contours represent
blue- and red-shifted components in each lobe, respectively, indicating that there is a velocity gradient along the minor axis of the outflow.
describe all the scientific results the SMA hourglass-like fashion exactly at the areas the Academia Sinica entered into an agree-
has been producing, some of the most where cloud contraction has been found via ment with the National Institutes of Natural
important results are highlighted below. kinematical studies . The role of mag- Sciences in Japan to join the ALMA project
netic support, the relation to filamentary or through the ALMA-Japan project. Taiwan
Molecular outflows are ubiquitous in flattened structures of molecular clouds and will contribute at the level of about 5% of
the star formation process, and a better envelopes, their interactions with outflows the Japanese effort. This Taiwanese effort
understanding of their nature is one of the and winds, are all currently being studied. as well as the Japanese effort represents
important problems. Previous research on the ALMA-East Asia (ALMA-EA) effort.
molecular outflows has revealed that the 3. ATACAMA LARGE MILLIME- Through this agreement, Taiwan has the
CO lines, which have been most often used TER/SUBMILLIMETER AR- right to propose for time from the Japanese
to observe molecular outflows, trace mostly RAY (ALMA) fraction of ALMA time. In October 2008,
material entrained by the central jets. The ALMA is the largest ground-based tele- the National Science Council in Taiwan
SMA has provided a big step forward in the scope that has ever been built. The and the US National Science Foundation
observations of the central jets themselves: array is now under construction in the reached an agreement for collaboration with
the SiO J = 8-7 and 5-4 lines have revealed Chajnantor area in the Atacama desert in ALMA-North America. The agreement is
very well collimated jetlike outflows. The northern Chile. The ALMA project has for Taiwan to contribute the equivalent of
jet consists of a chain of knots. Importantly, three major international partners: North 2 fully loaded 12-m telescopes. In return,
the SMA found possible rotation of the jets, America (NA), Europe (EU), and Japan. Taiwan has the right to propose from the
which is predicted by theory  [Fig. 2]. The NA and EU partners are responsible North American fraction of ALMA time,
By measuring the rotation of the jets, it is for the construction of the 12 m Array and also on all NRAO instruments. It is
possible to estimate the size scale of the (ALMA-baseline project), while Japan important to note that Taiwan did not ne-
launching point of the jets. is responsible for the construction of the gotiate for guaranteed time since the total
Atacama Compact Array (ACA; ALMA- Taiwan contribution is less than 3% of the
Magnetic field is another crucial element Japan project). The ALMA construction total ALMA effort. Astronomers in Taiwan
in the star formation process. The SMA can will be completed in 2012, and its expected have chosen a strategy to gain observation
trace the direction of magnetic fields at high lifetime is at least 50 years. time through open competition.
angular resolutions by observing polarized
dust emission. At an angular resolution Taiwan has been participating in the Although ASIAA is the lead agency
of 1”, previously smooth magnetic field ALMA project through ALMA-Japan and for the ALMA-Taiwan project, major
structures are found to be pinched in an ALMA-North America. In September 2005, universities having astronomy-related de-
12 AAPPS Bulletin October 2009, Vol. 19, No. 5
Submillimeter Astronomy in Taiwan
were delivered and made operational in
the lab in 2008-2009. At the same time,
EA FEIC members at ARL were trained
at ASIAA, SMA in Hawaii, and NRAO
in the US. In February 2008, the EA
FEIC started partial operation, and the
first front-end assembly from EA FEIC
was delivered to Chile in December 2008.
This very first unit from EA FEIC was
installed into one of the first two ALMA
antennas assembled and accepted at the
ALMA Operation Support Facility (OSF)
in Chile, and was used together with
another front-end assembly delivered by
FEIC in North America to obtain the first
astronomical fringe on the ALMA project.
Fig. 3: Test measurement system of EA FEIC, and a front-end assembly attached to the
measurement system. These are located in an environmental chamber, where temperature
and humidity are under control. In addition to EA FEIC, Taiwan has been
working on the following ALMA con-
struction projects: (1) joint development of
partments in Taiwan, i.e., National Central “ARClet-Taiwan” to support the users in SIS mixers with NAOJ for the band-10 re-
University, National Tsing Hua University, Taiwan. Actual functions of ARClet-T are ceivers, which cover the highest frequency
National Taiwan Normal University, Na- still under discussion. band in the ALMA project; (2) software
tional Taiwan University, National Cheng development in Garching, German and in
Kung University, and Tamkang Univer- 3.1. Taiwanese Contribution to the Socorro, New Mexico; (3) development of
sity have also participated in the project. ALMA Construction the Alternate Laser Synthesizer (ALS) for
These universities formed the university Taiwan has been making significant con- the ALMA Local Signal System. All these
consortium for ALMA-T (UCAT). ASIAA tributions for the ALMA construction. To efforts are underway.
and UCAT cooperate to promote ALMA date the largest Taiwanese contribution is
science in Taiwan. the East Asia Front-End Integration Cen- Industry in Taiwan has also been con-
ter (EA FEIC; see Fig. 3). Each ALMA tributing on the ALMA construction: (1)
Science preparation for future ALMA antenna is equipped with one front-end as- the CoTech company has a contract with
experiments is one of the crucial activities sembly, i.e., a receiver system to detect the ALMA-NA to build the nutating subre-
for the project. In particular, Taiwan and very weak radio signals from the universe. flectors for the ALMA-J 12-m telescopes,
Japan established the ALMA East Asia There are two other regional FEICs, one and (2) the CoTech company has also
Science Advisory Committee (EA SAC), in the US and the other in the UK. At each a contract with ALMA-NA to build the
which has held extensive discussions on regional FEIC, subassemblies delivered by ALMA Front End Service Vehicles. The
what kinds of ALMA science should be suppliers all over the world are integrated long cooperation that ASIAA has had
promoted in the East Asia region and how into each front-end assembly, and their with the Taiwanese industries over the last
to promote such science. EA SAC has performances after the integration are ten years has played an important role in
also been organizing ALMA-EA Science verified through various tests. After verifi- promoting ALMA technical projects in
Workshops to provide the occasions for the cation of the performance, the FEIC ships Taiwan. We are looking forward to more
community in Taiwan and Japan to discuss out each front-end assembly to the ALMA projects like these.
potential ALMA science together. site in Chile. EA FEIC will deliver all the
front-end assemblies for the ACA system. REFERENCES
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