[논문]기술문명징후 탐색

Sungwook E. Hong; Bong Won Sohn; Taehyun Jung; Min-Su Shin; Hyunwoo Kang; Minsun Kim

doi:10.5303/pkas.2023.38.2.075

기술문명징후 탐색
SEARCH FOR TECHNOSIGNATURE 원문보기

천문학논총 = Publications of the Korean Astronomical Society, v.38 no.2, 2023년, pp.75 - 89

Sungwook E. Hong (Korea Astronomy and Space Science Institute) , Bong Won Sohn (Korea Astronomy and Space Science Institute) , Taehyun Jung (Korea Astronomy and Space Science Institute) , Min-Su Shin (Korea Astronomy and Space Science Institute) , Hyunwoo Kang (Korea Astronomy and Space Science Institute) , Minsun Kim (Korea Astronomy and Space Science Institute)

Abstract ▼ AI-Helper

Technosignature, previously known as SETI(search for extraterrestrial intelligence), is the scientific evidence of past or present extraterrestrial civilizations. Since NRAO's Project Ozma was performed in 1960, most of the noticeable technosignature searches have been done by radio telescopes, hoping to find strong and narrow bandwidth signals that cannot be explained by known natural processes. Recently, the Breakthrough Listen project has opened a new opportunity for technosignature by utilizing both optical telescopes, radio telescopes, and next-generation radio telescope arrays. In this review, mainly based on NASA Technosignatures Workshop (2018), we review the current trends of technosignature surveys, as well as other possible methods for detecting technosignature. Also, we suggest what the Korean community could contribute the technosignature research, including the new SETI project with Korea VLBI Network (KVN).

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표/그림 (18)

그림 Figure 1. On August 15, 1997, the Big Ear radio telescope at Ohio State University received a strong narrowband radio signal. Astronomer Jerry R. Ehman discovered the anomaly. (Credit: Big Ear Radio Observatory, North American Astro- Physical Observatory (NAAPO), Source: Fig. 3 of Kraus (1979))
그림 Figure 2. Searches for extraterrestrial intelligence (SETI) have grown in reach since a first survey in 1960. But if Earth's oceans represent all possible searches, SETI re- searchers have scanned only a hot tub's worth. (Credit: (Graphic) N. Desai/Science; (Data) Jason Wright/PENN State; Source: Fig. 2 of Clery (2020); reprinted with per- mission from AAAS; permission of reusing the figure must be obtained from the original copyright holder)
그림 Figure 3. An example of axes of merit for a certain technosig- nature project. It can help the government and academic so- ciety to determine the priorities for various technosignature- related projects. (Credit: S. Sheikh; Source: Fig. 1 of NASA Technosignatures Workshop (2018))
그림 Figure 4. A cartoon of the three directions of target selec- tion and the relative advantages of Breakthrough Listen's primary programs observing stars and galaxies (green), a survey of the Breakthrough Listen Exotica Catalog (blue), and some example campaigns. Previous SETI surveys have generally aimed for maximal depth, achieving strong limits for a small number of similar targets, or count, achieving modest limits for a large number of similar targets. Other exotica efforts can include high-depth (red) or high-count (gold) campaigns, but observations of the Exotica Catalog will be broad, achieving modest limits on a small number each of a wide variety of targets. Future discoveries may be added to a later version of the catalog (pale blue), or prompt new campaigns that we cannot yet plan for (gray). (Source: Fig. 1 of Lacki et al. (2021); reprinted with permission from AAAS; permission of reusing the figure must be obtained from the original copyright holder)
그림 Figure 5. H-R Diagram of the 5-50 pc subsample of target stars for Breakthrough Listen. Domains of B - V and M_V were constructed along the main sequence, within which the nearest 100 stars were selected to be included in the final Breakthrough Listen target list. In addition, a domain of gi- ant stars was constructed and the nearest 100 such stars were identified. (Source: Fig. 2 of Isaacson et al. (2017); used with permission of ⓒ The Astronomical Society of the Pacific; permission conveyed through Copyright Clearance Center, Inc.; permission of reusing the figure must be obtained from the original copyright holder)
그림 Figure 6. Sky map of all TESS TOIs (blue dots), with transit- ing TESS targets analyzed in Franz et al. (2022) overlaid as red x's. The grey-shaded region is the zone above declination -20º where BL targets are usually observed with the GBT; BL targets below this declination are usually observed at the Parkes Observatory. (Source: Fig. 1 of Franz et al. (2022))
표 Table 1 Breakthrough Listen Facilities
그림 Figure 7. The signal of interest, BLC1, from our search of Prox Cen. Here, Smith et al. (2021) plots the dynamic spectrum around the signal of interest over an eight-pointing cadence of on-source and off-source observations. BLC1 passes their coincidence filters and persists for over 2h. The red dashed line, purposefully offset from the signal, shows the expected frequency based on the detected drift rate (0.038 Hz/s) and start frequency in the first panel. BLC1 is analysed in detail in Sheikh et al. (2021a). (Source: Fig. 4 of Smith et al. (2021))
그림 Figure 8. Automated Planet Finder (APF) installed at the Lick Observatory. (Source: Fig. 1 of Vogt et al. (2014); used with permission of ⓒThe Astronomical Society of the Pacific; permission conveyed through Copyright Clearance Center, Inc.; permission of reusing the figure must be obtained from the original copyright holder)
표 Table 2 Basic characteristics of BLC1 (Sheikh et al., 2021a)
그림 Figure 9. Examples of technosignature studies done by APF. Top: Periodogram of a stellar spectrum. (Source: Fig. 2 of Isaacson et al. (2019)) Bottom: Spectrum of Boyajian's star. (Source: Fig. 1 of Lipman et al. (2019)) (Both figures used with permission of ⓒThe Astronomical Society of the Pacific; permission conveyed through Copyright Clearance Center, Inc.; permission of reusing the figure must be obtained from the original copyright holder)
그림 Figure 10. SEDs of an old elliptical galaxy (black) and a typical Sd spiral (green) normalized by their optical flux. In blue is the old elliptical with 10% of the starlight reprocessed as 300 K waste heat. (Source: Fig. 1 of Wright et al. (2019))
그림 Figure 11. Sources common to WISE and the 2MASS XSC, including the starlights with and without waste heat. (Source: Fig. 2 ofWright et al. (2019), adopted from Fig. 3 of Wright et al. (2014); reprinted with permission from AAAS; permission of reusing the figure must be obtained from the original copyright holder)
표 Table 3 Observable frequency bands in KVN
표 Table 4 Estimated technosignature detection with KVN
그림 Figure 12. The turboSETI pipeline adapted for compatibility with the Google Cloud Platform. (Source: Fig. 4 of Traas et al. (2021); reprinted with permission from AAAS; permission of reusing the figure must be obtained from the original copyright holder)
그림 Figure 13. High-resolution spectrographs that KASI is codeveloping. Top: IGRINS-2 (Credit: UT Austin; Source: https://www.as.utexas.edu/astronomy/research/people/jaffe/igrins.html). Middle: MagNIFIES (Credit: UT Austin; Source: http://m-worthington.com/gmtnirs/). Bottom: GCLEF (Credit: SAO/Harvard; Source: https://www.gmt.iag.usp.br/telescopio/a-instrumentacao-do-gmt).
표 Table 5 Specifications of three high-resolution spectrographs that KASI is co-developing, compared by the APF.

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표제어: PCR

동의어: Packet Collision Rate

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용어 설명: PCR은 세균 특이성이 있는 primer를 이용하여 적은 수의 세균이 있을지라도 쉽게 검출할 수 있는 유용한 방법이며, 이를 이용하여 구강 내 치면세균막이나 타액에서 직접 세균을 검출할 수 있게 되었다[8].

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