| Seminar: |
CPS Seminar
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| date: |
2022 July 29 (FRI) 17:00-19:00
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| Room: |
Online seminar (Zoom)
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| Speaker: |
MIYOSHI Makoto (Assistant Professor, JASMINE Project, National Astronomical Observatory of Japan)
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| Title: |
"Is the EHTC "ring" image of M87 black hole real? --- Results of independent analysis of the EHTC data ----."
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| Abstract: |
We performed an independent reanalysis of the EHTC public data and obtained imaging results that are different from the ring image shown by the EHTC. Why the different imaging results? Which one is correct? We explain the issues in this talk.(1) Why the different imaging results?There is a sampling bias in the data (i.e., it tends to create structures with about 40 microarcseconds scales),and EHTC's narrow setting of the field of view enhanced this bias effect, resulting in the about 40 microarcseconds ring. While we performed a normal imaging analysis with a wide field of view setting (25 milliarcseconds), which is less subject to the bias effect; EHTC claims that a wide field of view cannot be obtained, but theoretical calculations of radio interferometry show that a wider range of view than that of EHTC thought.(2) Which is correct? Admitting that our result is not perfect yet, but it is more correct than the EHTC's ring image.The pieces of evidence are following.(a) Our results are consistent with the previous observations, such as the detection of the famous M87 jet structure.(b) Our results show much better agreement between the data and imaging results than the case of the EHTC ring image.(c) The EHTC ring is a structure tend to create from the EHT array configuration (u-v cover), and the ring image can be produced from simulated data (point source data).
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| Keywords: |
sampling bias, M87 black hole imaging
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| Organizer: |
MAKINO Junichiro
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