2016 Fiscal Year Research-status Report
Dust-free Insight into the Obscured Cosmic Accretion History and Modes of Galaxy Assembly
| Project/Area Number |
15K17604
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| Research Institution | The University of Tokyo |
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Principal Investigator |
RUJOPAKARN WIPHU 東京大学, カブリ数物連携宇宙研究機構, 特任研究員 (60731776)
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| Project Period (FY) |
2015-04-01 – 2018-03-31
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| Keywords | Galaxy Evolution / Radio Astronomy / Ultra-deep sky survey |
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| Outline of Annual Research Achievements |
We have made the first characterization of the distribution of star formation in a representative sample of star-forming galaxies at the peak epoch of galaxy assembly, one of the key goals of the proposed research. This is accomplished by conducting the most sensitive observations to date of an area of the sky called “Hubble Ultra-Deep Field” (HUDF) using the Jansky Very Large Array (VLA) and the Atacama Large Millimeter/sub-millimeter Array (ALMA). This level of sensitivity is required to image the typical population of star-forming galaxies, i.e., the population relevant to our understanding of the place where most stars in the present-day universe were formed. Our extinction-independent, sub-arcsecond-resolution imaging of the HUDF shows that typical star-forming galaxies have extended star-forming sizes comparable to the extent of their stellar mass distributions. This finding is a direct evidence confirming that galaxies assemble most of their stellar mass via accretion of cold gas, which leads to gas-rich, unstable disks and in-situ disk-wide star formation. Furthermore, we have discovered that intense star formation are occurring co-spatially with supermassive black hole accretion based on the combination of VLA and ALMA observations, which favors the scenario of in-situ and concurrent growth of both bulge and supermassive black hole, another key goal of our research.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The key output from this program is the deepest image of the sky at the radio frequency. We have published/submitted three journal papers using this data to date (with three more being prepared). The data was used to help guide three other ALMA observing programs in the HUDF and its vicinity area, as well as to plan some of the first observations of the upcoming James Webb Space Telescope. These stretched attainment were not envisioned in the originally proposed program. Overall, the project has progressed better than the original plan.
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| Strategy for Future Research Activity |
We will submit three more papers using this radio data. We have used the results from this program to submit an ALMA proposal in Cycle 5 to conduct high resolution observation of two of the galaxies in the sample of Rujopakarn et al. (2016) to search for substructures of star formation, which will provide a more stringent test for the galaxy assembly scenario. The PI is now a member of the James Webb Space Telescope’s Near Infrared Camera (NIRCam) Guaranteed Time Observations team to further expand and deepen this research work.
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| Causes of Carryover |
The PI is being invited to give a talk in July 2017, and therefore
wish to use the Kakenhi fund to travel to present result in FY2017.
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| Expenditure Plan for Carryover Budget |
Attend a conference in Durham, UK
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