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Improvement in resolution and sensitivity from SMA subcompact (left, resolution of 2”) to SMA extended (middle, resolution of 0.7”) to ALMA (resolution of 0.26”) towards the high-mass star-forming cores W51 e2 (top) and W51 e8 (bottom). Contours are dust continuum. Red segments indicate magnetic field orientations measured from dust polarization in Band 6 (220 GHz) with ALMA and at 345 GHz with the SMA (Koch et al. 2018, ApJ, 855, 39).
A First Glimpse of ALMA at the High-Mass Star-Forming Region W51
NA 12m Vertex prototype antenna at the JVLA site in Socorro, New Mexico.
NA 12m Vertex prototype antenna at the JVLA site in Socorro, New Mexico.
Cleaned SZE images of clusters observed by seven-element AMiBA. The white circles indicate the half-maximum contour of the primary beam (the field of view; 23'), and the blue patches at the bottom-right corners show the half-maximum regions of the dirty beams (~6').
The first SZE signal with the 7-element AMiBA
Delegation from Taiwan during the ALMA inauguration in March 2013 at the OSF in Chile.
Delegation from Taiwan during the ALMA inauguration in March 2013 at the OSF in Chile.
the procured NA 12m Vertex prototype antenna at the JVLA site in Socorro, New Mexico.
the procured NA 12m Vertex prototype antenna at the JVLA site in Socorro, New Mexico.
the latest tuCASA-ASIAA imaging workshop held at National Normal University ShiDa
the latest tuCASA-ASIAA imaging workshop held at National Normal University ShiDa
the ALMA alternative laser synthesizer
the ALMA alternative laser synthesizer
Nutating subreflector in the laboratory at ASIAA.
Nutating subreflector in the laboratory at ASIAA
EA-FEIC staff members celebrating the delivery of the very last front-end for Europe in 2012.
EA-FEIC staff members celebrating the delivery of the very last front-end for Europe in 2012.
EA FEIC team delivering the first front end to Chile in 2008.
EA FEIC team delivering the first front end to Chile in 2008.
One of the front ends during testing and integration at the EA FEIC in Taichung, Taiwan. Pictured is the tilt table holding the cryogenic dewar (in blue) in which the receiver units are installed and tested.
the front ends during testing and integration at the EA FEIC
An aerial view of the technical building at the AOS at 5000m
An aerial view of the technical building at the AOS at 5000m
To the right are the three antenna assembly sites belonging to the Japanese, North American and European partners; in the upper middle section is the operations building, and in the upper right, the road to the Chajnantor Plain.
Aerial view of the Operations Support Facilities (OSF) at around 2900m.
ALMA antennas on the Chajnantor plateau in Chile. (Picture Credit: C. Padilla, ALMA, ESO/NAOJ/NRAO)
ALMA antennas on the Chajnantor plateau in Chile
EA-FEIC staff members celebrating the delivery of the last receiver front-end system for our ALMA-Japan partner (blue cylinder-shaped object in the middle of the photo).
EA-FEIC staff members celebrating the delivery of the last receiver front-end system for our ALMA-Japan partner
The AMiBA receiver with the vacuum chamber removed (Chen et al., 2009, ApJ, 694, 1664).
The AMiBA receiver with the vacuum chamber removed
Left Figure: SMA dust continuum observation at 345 GHz of the star-forming core W51 e2 with a resolution of about 0.7 arcsec. The color-wedge indicates the dust emission intensity. The measured magnetic field morphology (white segments), shows that gravity is bending the field lines almost radially and pulling them toward the core center. Overlaid in blue are the intensity gradients of the dust emission. The correlation between field and intensity gradient orientations is used as a starting point in our method. Right Figure: Resulting field strength map for W51 e2. An increase in field strength toward the center is apparent.
A New Method for Magnetic Field Strength Maps for Molecular Clouds
SMA observational results of the dust continuum emission at wavelengths of 870 micron (color scales and contours) and the magnetic field projected in the plane of sky (shown in segments). The observed magnetic field orientations (red segments) on the ∼0.3 pc scale with the SMA subcompact configuration (SMA-SubC, color scale and cyan contours) shows some mirror-symmetry features from north to south. Here, the field lines might be channeling and aligning material from both north and south. At a∼60 mpc scale resolution observed with the SMA extended configuration (SMA-Ext), dense cores are, indeed, detected along the east–west mirror symmetry axis (black contours). Smooth changes in field morphologies (white segments) are found within individual cores, whereas large overall changes in position angles can occur in between the cores.
Dust continuum and polarization from envelope to cores in star formation: a case study in the W51 North region
Left: Contour plot of the antenna beam pattern measured in the far field. The units are in decibels. The cross-structure around the secondary sidelobes is likely to result from scattering of the secondary-mirror support structure. Right: One-dimensional scans, extracted from the left panel, parallel to the x- and y-axes after location of the main beam maximum. Overlaid is the simulation result for the E-plane at 95 GHz.
1.2 m Shielded Cassegrain Antenna for Close-Packed Radio Interferometer
Magnetic field strength map for the collapsing core W51 e2, calculated with the polarization-intensity gradient method (Koch, Tang and Ho, 2012, ApJ 747(1), 79, 2012-03).
Mapping the Magnetic Field Strength in Molecular Clouds: W51 e2
Koch, Patrick
Associate Research Fellow (Tenured)
photo of Koch, Patrick
Office: ASMAB 1419
TEL: +886-2-2366-5478
FAX: +886-2-2367-7849
Email: pmkoch_replace2@_asiaa.sinica.edu.tw

Education and Positions

  • Associate Research Fellow, ASIAA (2016~present)
  • Assistant Research Fellow, ASIAA (2011~2015)
  • Research Scientist, ASIAA (2006~2010)
  • Postdoctoral Fellow, ASIAA (2003~2006)
  • Ph.D., Physics, University of Zurich, Switzerland (2003)
  • M.S., Physics, ETH Zurich, Switzerland (1999)
  • B.S., Physics, ETH Lausanne, Switzerland (1996)
  • B.S., Mechanical Engineering, ETH Lausanne, Switzerland (1995)

Honors & Awards

  • Career Development Award, Academia Sinica (2015~2019)
  • Significant Research Achievement, Academia Sinica (2012)

Research Interests

  • Structure Formation, Magnetic Fields, Turbulence
  • Star, Disk, and Planet Formation
  • Galactic Center
  • Clusters of Galaxies: SZ Effect, Cluster Mergers, Turbulence, Plasma Physics Processes
  • Observational and Analysis Techniques
  • Telescope Commissioning

Recent Journal Papers

Complete List of Publications

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TEL: 886-2-3365-2200 FAX: 886-2-2367-7849
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