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    Contributions to the Cosmic Reionization and Growth of the First Supermassive Black Holes

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    ํ•™์œ„๋…ผ๋ฌธ(๋ฐ•์‚ฌ)--์„œ์šธ๋Œ€ํ•™๊ต ๋Œ€ํ•™์› :์ž์—ฐ๊ณผํ•™๋Œ€ํ•™ ๋ฌผ๋ฆฌยท์ฒœ๋ฌธํ•™๋ถ€(์ฒœ๋ฌธํ•™์ „๊ณต),2019. 8. ์ž„๋ช…์‹ .๊ณ ์ ์ƒ‰ํŽธ์ด(z > 5)์˜ ์ดˆ๊ธฐ ์šฐ์ฃผ์—์„œ, ์–ด๋‘์šด ํ€˜์ด์‚ฌ๋Š” ์ „์ฒด ํ€˜์ด์‚ฌ์˜ ๋Œ€๋ถ€๋ถ„์„ ์ด๋ฃจ๊ณ  ์žˆ๋‹ค. ํ•˜์ง€๋งŒ ๊ทธ๋“ค์˜ ์–ด๋‘์šด ๋ฐ๊ธฐ ๋•Œ๋ฌธ์—, ๊ด€๋ จ ์—ฐ๊ตฌ๋“ค์€ ์ œํ•œ๋œ ๋ฒ”์œ„์—์„œ ์ตœ๊ทผ์—์„œ์•ผ ๋“œ๋ฌผ๊ฒŒ ์ด๋ฃจ์–ด์กŒ๋‹ค. ๋ณธ ํ•™์œ„๋…ผ๋ฌธ์—์„œ๋Š” ๊ณ ์ ์ƒ‰ํŽธ์ด์˜ ์–ด๋‘์šด(M_1450 > -24 mag) ํ€˜์ด์‚ฌ์— ๋Œ€ํ•ด ๋‹ค์–‘ํ•œ ๋ฐฉ๋ฉด์—์„œ ์—ฐ๊ตฌ๋ฅผ ์ง„ํ–‰ํ–ˆ๋‹ค. ์ฒซ์งธ๋กœ, ์ ์ƒ‰ํŽธ์ด 6์— ์žˆ๋Š” ์–ด๋‘์šด ํ€˜์ด์‚ฌ๋ฅผ ์ฐพ๊ธฐ ์œ„ํ•œ ์—ฐ๊ตฌ๋ฅผ Infrared Medium-deep Survey (IMS) ๊ทผ์ ์™ธ์„  ์ด๋ฏธ์ง€ ์ž๋ฃŒ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ์ง„ํ–‰ํ•˜์˜€๋‹ค. ์ด 86 deg^2์˜ ์˜์—ญ์—์„œ ์ƒ‰ ์„ ํƒ ๋ฐฉ๋ฒ•์„ ์ด์šฉํ•ด 25๊ฐœ์˜ ํ€˜์ด์‚ฌ ํ›„๋ณด๋ฅผ ์„ ๋ณ„ํ•˜์˜€๊ณ , ์ด๋ฒˆ ์—ฐ๊ตฌ์—์„œ ์ƒˆ๋กญ๊ฒŒ ๋ฐœ๊ฒฌ๋œ IMS J2204+0112๋ฅผ ํฌํ•จํ•˜์—ฌ ๊ทธ๋“ค ์ค‘ 3๊ฐœ์˜ ํ›„๋ณด๋Š” ๋ถ„๊ด‘ ๊ด€์ธก์„ ํ†ตํ•ด ์ ์ƒ‰ํŽธ์ด 6์— ์žˆ๋Š” ํ€˜์ด์‚ฌ์ž„์ด ํ™•์ธ๋˜์—ˆ๋‹ค. ์ด๋Ÿฌํ•œ ํ€˜์ด์‚ฌ ๋ฐ ํ€˜์ด์‚ฌ ํ›„๋ณด๋กœ๋ถ€ํ„ฐ ์ ์ƒ‰ํŽธ์ด 6์—์„œ์˜ ํ€˜์ด์‚ฌ ๊ด‘๋„ ๊ณก์„ ์„ ๊ตฌํ–ˆ์œผ๋ฉฐ, ์ด ๊ณก์„ ์œผ๋กœ๋ถ€ํ„ฐ ์ดˆ๊ธฐ ์šฐ์ฃผ์˜ ์ค‘์„ฑ ์ˆ˜์†Œ๋“ค์„ ๋ชจ๋‘ ์ด์˜จํ™”์‹œํ‚ค๋Š”๋ฐ ํ•„์š”ํ•œ ๊ด‘์ž์˜ 15 % ๋ฏธ๋งŒ์ด ํ€˜์ด์‚ฌ๋กœ๋ถ€ํ„ฐ ๋ฐฉ์ถœ๋˜๋Š” ๊ฒƒ์œผ๋กœ ๊ณ„์‚ฐ๋˜์—ˆ๋‹ค. ์ฆ‰ ์ดˆ๊ธฐ ์šฐ์ฃผ์˜ ์žฌ์ด์˜จํ™” ๊ณผ์ •์— ํ€˜์ด์‚ฌ๋Š” ๊ทธ๋ฆฌ ๋งŽ์ง€ ์•Š์€ ๊ธฐ์—ฌ๋ฅผ ํ•œ ๊ฒƒ์œผ๋กœ ํ™•์ธ๋˜์—ˆ๋‹ค. ๋‘˜์งธ๋กœ, ๊นŠ์€ ๊ทผ์ ์™ธ์„  ๋ถ„๊ด‘ ๊ด€์ธก์„ ํ†ตํ•ด์„œ IMS J2204+0112์˜ ์ค‘์‹ฌ๋ถ€์— ์žˆ๋Š” ์ดˆ๊ฑฐ๋Œ€์งˆ๋Ÿ‰ ๋ธ”๋ž™ํ™€์˜ ์งˆ๋Ÿ‰์„ ์ธก์ •ํ•˜์˜€๋‹ค. ๋ธ”๋ž™ํ™€ ์ฃผ๋ณ€์˜ ๊ฐ€์Šค๋“ค์˜ ๋น„๋ฆฌ์–ผ(Virial) ์šด๋™์„ ๊ฐ€์ •ํ•˜์—ฌ, ์ ์ƒ‰ํŽธ์ด๋œ CIV 1549 ๋ฐฉ์ถœ์„ ์„ ํ†ตํ•ด ๋ธ”๋ž™ํ™€ ์งˆ๋Ÿ‰์ด M_BH = 1.2 x 10^9 M_sun ์ž„์„ ์ธก์ •ํ•˜์˜€๊ณ , ๊ทธ ๊ฒฐ๊ณผ ์—๋”ฉํ„ด ๋น„์œจ์ด R_Edd ~ 0.1์ž„์„ ํ™•์ธํ–ˆ๋‹ค. ์ด ๊ฐ’์€ ์ง€๊ธˆ๊นŒ์ง€ ์•Œ๋ ค์ง„ ์ ์ƒ‰ํŽธ์ด 6 ํ€˜์ด์‚ฌ์˜ ์—๋”ฉํ„ด ๋น„์œจ ์ค‘ ๊ฐ€์žฅ ๋‚ฎ์€ ๊ฐ’๋“ค์— ์†ํ•˜๋ฉฐ, ์ดˆ๊ธฐ ์šฐ์ฃผ์˜ ์ดˆ๊ฑฐ๋Œ€์งˆ๋Ÿ‰ ๋ธ”๋ž™ํ™€์€ ๋ชจ๋‘ ๊ธ‰๊ฒฉํ•˜๊ฒŒ ์„ฑ์žฅํ•œ๋‹ค๊ณ  ์•Œ๋ ค์ง„ ์‚ฌ์‹ค์˜ ๋ฐ˜๋ก€๊ฐ€ ๋˜์—ˆ๋‹ค. ์ด๋ ‡๊ฒŒ ๋‚ฎ์€ ์—๋”ฉํ„ด ๋น„์œจ์„ ๊ฐ€์ง„ ํ€˜์ด์‚ฌ๋Š” 100 M_sun์˜ ๋ธ”๋ž™ํ™€์ด ์Šˆํผ ์—๋”ฉํ„ด ๊ฐ•์ฐฉ์„ ๊ฒช๊ฑฐ๋‚˜ 10^5 M_sun ์ •๋„์˜ ์งˆ๋Ÿ‰์„ ๊ฐ–๋Š” ๋ฌด๊ฑฐ์šด ๋ธ”๋ž™ํ™€์ด ์—๋”ฉํ„ด ์ œํ•œ์ ์ธ ๊ฐ•์ฐฉ์„ ๊ฒช์œผ๋ฉด์„œ ์„ฑ์žฅํ•˜๋Š” ๊ฒƒ์œผ๋กœ ์„ค๋ช…๋  ์ˆ˜ ์žˆ๋‹ค. ๋˜ํ•œ IMS J2204+0112๋ฅผ ํฌํ•จํ•˜์—ฌ, ์ ์ƒ‰ํŽธ์ด 6 ํ€˜์ด์‚ฌ์˜ ๋ณธ์งˆ์ ์ธ ์—๋”ฉํ„ด ๋น„์œจ ๋ถ„ํฌ๋ฅผ ๊ณ„์‚ฐํ•˜์˜€๊ณ , ์ ์ƒ‰ํŽธ์ด 2์˜ ํ€˜์ด์‚ฌ์™€ ๋น„๊ตํ–ˆ์„ ๋•Œ ๊ทธ ๊ฐ’์ด 0.35 dex ์ •๋„ ์•ฝ๊ฐ„ ๋†’์€ ๊ฒƒ์œผ๋กœ ํ™•์ธ๋์œผ๋ฉฐ, ์ด๋ฅผ ํ†ตํ•ด ์ดˆ๊ธฐ ์šฐ์ฃผ ์ดˆ๊ฑฐ๋Œ€์งˆ๋Ÿ‰ ๋ธ”๋ž™ํ™€์˜ ์„ฑ์žฅ์— ๋Œ€ํ•ด ์ œ์•ฝ์„ ์ฃผ์—ˆ๋‹ค. ์…‹์งธ๋กœ, Atacama Large Millimeter/submillimeter Array (ALMA)๋ฅผ ์ด์šฉํ•œ IMS J2204+0112์˜ sub-mm ์˜์—ญ ๊ด€์ธก์„ ํ†ตํ•˜์—ฌ, ํ•ด๋‹น ํ€˜์ด์‚ฌ์˜ ๋ชจ์€ํ•˜๊ฐ€ 500-700 M_sun yr^(-1)์˜ ๋ณ„์ƒ์„ฑ๋ฅ ์„ ๊ฐ–๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๊ณ , ์ด ๊ฐ’์€ ๋น„์Šทํ•œ ๋ฐ๊ธฐ๋ฅผ ์ง€๋‹Œ ์—๋”ฉํ„ด ๋น„์œจ์ด ๋†’์€ ํ€˜์ด์‚ฌ๋ณด๋‹ค 10๋ฐฐ ์ •๋„ ๋†’์€ ๊ฐ’์ด๋‹ค. ํฅ๋ฏธ๋กญ๊ฒŒ๋„, IMS J2204+0112์™€ ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ ๋‚ฎ์€ ์—๋”ฉํ„ด ๋น„์œจ(R_Edd < 0.2)์„ ๊ฐ–๋Š” ํ€˜์ด์‚ฌ๊ฐ€ ๋ชจ๋‘ ๋ณ„์ƒ์„ฑ๋ฅ ์ด ๋†’์€ ์€ํ•˜๋“ค์— ์†ํ•ด์žˆ๋Š” ๊ฒƒ์„ ํ™•์ธํ–ˆ๊ณ , ์ด๋Š” ๋จผ์ € ๋น ๋ฅด๊ฒŒ ์„ฑ์žฅํ•˜๋Š” ์ดˆ๊ฑฐ๋Œ€์งˆ๋Ÿ‰ ๋ธ”๋ž™ํ™€๊ณผ ๋’ค๋”ฐ๋ผ ์„ฑ์žฅํ•˜๋Š” ๋ชจ์€ํ•˜์— ๋Œ€ํ•œ ์ตœ๊ทผ ์‹œ๋ฎฌ๋ ˆ์ด์…˜๊ณผ ์ผ์น˜ํ•˜๋Š” ๊ฒฐ๊ณผ์ด๋‹ค. ์ด์— ๋”ฐ๋ฅด๋ฉด, ๋‚ฎ์€ ์—๋”ฉํ„ด ๋น„์œจ์„ ๊ฐ–๋Š” ํ€˜์ด์‚ฌ์˜ ์ดˆ๊ฑฐ๋Œ€์งˆ๋Ÿ‰ ๋ธ”๋ž™ํ™€์€ ์„ฑ์žฅ์ด ๊ฑฐ์˜ ๋๋‚˜๊ฐ€๋Š” ๋‹จ๊ณ„์— ์žˆ์œผ๋ฉฐ, ๋ฐ˜๋ฉด ๊ทธ๋“ค์˜ ๋ชจ์€ํ•˜๋Š” ๋” ์„ฑ์žฅํ•  ๊ฐ€๋Šฅ์„ฑ์ด ์žˆ๋‹ค. ๋งˆ์ง€๋ง‰์œผ๋กœ, ๋Œ€์—ญํญ์ด 500 A์ธ ์ค‘๋Œ€์—ญ ํ•„ํ„ฐ๋ฅผ ๊ด€์ธก์„ ๋ฐ”ํƒ•์œผ๋กœํ•œ ์ƒ‰ ์„ ํƒ ๋ฐฉ๋ฒ•์„ ์ด์šฉํ•˜์—ฌ ์ ์ƒ‰ํŽธ์ด 5์˜ ์–ด๋‘์šด ํ€˜์ด์‚ฌ ํƒ์‚ฌ๋ฅผ ์ง„ํ–‰ํ•˜์˜€๋‹ค. ๊ฐ€์‹œ๊ด‘ ์˜์—ญ์˜ ๋ถ„๊ด‘ ๊ด€์ธก์„ ํ†ตํ•ด์„œ -25 5), but they are hidden owing to their brightness, and so related research has only been conducted rarely in recent years. In this thesis, faint high-redshift quasars with M_1450 > -24 mag are studied in various ways. First, the survey of faint quasars at z ~ 6 was performed with the near-infrared (NIR) imaging data from the Infrared Medium-deep Survey (IMS). Over an area of 86 deg^2, thirteen quasar candidates were selected by the color-selection technique, three of which were spectroscopically identified as quasars at z ~ 6, including IMS J2204+0112 that is newly discovered in this work. The z = 6 quasar luminosity functions (QLFs) were derived from the samples consisting of these three quasars and/or quasar candidates, resulting in the low ionizing photon density that is only < 15 % of the amount required to fully ionize neutral hydrogen in the universe. This suggests the minor contribution of high-redshift quasars to the cosmic reionization. Second, the black hole mass (M_BH) of a supermassive black hole (SMBH) centered at IMS J2204+0112 was estimated through deep NIR spectroscopy. Assuming the virial motion of gas around the SMBH, its M_BH was measured from the redshifted CIV 1549 emission line as M_BH = 1.2 x 10^9 M_sun, resulting in the Eddington ratio of R_Edd ~ 0.1. This is one of the lowest R_Edd values of z > 6 quasars discovered so far, which breaks the decadal belief on extremely growing SMBHs in the early universe. Such a low R_Edd quasar can grow from a 100 M_sun seed black hole with episodic super-Eddington accretion or from a heavy black hole of ~10^5 M_sun with Eddington-limited accretion. Furthermore, the inclusion of IMS J2204+0112 gives the intrinsic R_Edd distribution of z ~ 6 quasars that has slightly higher R_Edd values by 0.35 dex than that of z ~ 2 quasars, giving a constraint to the SMBH growth in the early universe. Third, based on the sub-mm observations of IMS J2204+0112 with the Atacama Large Millimeter/submillimeter Array (ALMA), its host galaxy is found to have a star formation rate (SFR) of 500-700 M_sun yr^(-1), which is an order of magnitude higher than those of the luminosity-matched z ~ 6 quasars with high R_Edd. Interestingly, all of the low R_Edd quasars like IMS J2204+0112 known so far (R_Edd < 0.2) are also hosted by high SFR galaxies, corresponding to the recent simulation of the preceding SMBH growth and the subsequent formation of its host galaxy. Following this picture, such low R_Edd quasars are in the end stage of SMBH evolution, while their host galaxies can afford to grow more. Finally, the z ~ 5 faint quasar survey with IMS was conducted using the advanced selection method with medium-band observations, where the medium-band filters have a bandwidth of 500 A. Through the optical spectroscopy of the selected candidates, ten quasars with -25 20 % of the broad-band-selected candidates. Also, the inclusion of medium-band data improves the accuracy of the photometric redshift determination to= 0.016. Consequently, the medium-band-based approach is a cost-effective way to find high-redshift quasars even with their accurate redshifts.1 Introduction 1 1.1 Active Galactic Nucleus 1 1.2 Discovery of Quasars in the Early Universe 3 1.3 Quasar Contributions to the Cosmic Reionization 8 1.4 Growth of the First Supermassive Black Holes 11 1.5 Black Hole-Galaxy Co-evolution at High Redshift 14 1.6 Thesis Outline 18 2 Survey of Faint z ~ 6 Quasars in IMS and Implications for the Cosmic Reionization 19 2.1 Introduction 19 2.2 IMS and CFHTLS Data 21 2.3 Quasar Candidate Selection 35 2.4 Spectroscopic Data 40 2.4.1 Gemini/GMOS Observation of IMS J2204+0112 40 2.4.2 Supplemental Data 41 2.5 Quasar Luminosity Function at z ~ 6 44 2.5.1 Photometric Completeness 44 2.5.2 Quasar Selection Function 44 2.5.3 Binned Luminosity Function 48 2.6 Implication for the Cosmic Reionization 52 2.7 Summary 54 3 Low Eddington Ratio of a Faint Quasar at z ~ 6: Not Every Supermassive Black Hole is Growing Fast in the Early Universe 57 3.1 Introduction 57 3.2 Observation and Data Analysis 60 3.3 Spectral Modeling 63 3.3.1 Continuum Components 63 3.3.2 C IV Line Measurement 68 3.4 Results 71 3.4.1 Black Hole Mass 71 3.4.2 Eddington Ratio 73 3.5 Discussion 80 3.5.1 Growth of IMS J2204+0112 80 3.5.2 Intrinsic Eddington Ratio Distribution of z ~ 6 Quasars 81 3.6 Conclusion 87 4 High Star Formation Rates of Low Eddington Ratio Quasars at z ~ 6 89 4.1 Introduction 89 4.2 Observations and Data 92 4.2.1 ALMA 92 4.2.2 SCUBA-2 93 4.2.3 Ancillary Data 93 4.3 Results 96 4.3.1 Sub-mm Continuum Maps of IMS J2204+0112 96 4.3.2 FIR Luminosity and Star-formation Rate 101 4.4 Discussion 105 4.4.1 FIR Excess of IMS J2204+0112 105 4.4.2 SMBH Activity and Star Formation 113 4.5 Summary 115 5 Discovery of Faint Quasars at z ~ 5 with a Medium-band-based Approach 119 5.1 Introduction 119 5.2 Initial Sample Selection 123 5.2.1 CFHTLS and IMS Imaging Data 123 5.2.2 Broadband Color Selection 129 5.3 Medium-Band Selection 134 5.3.1 Medium-band Observation 134 5.3.2 Medium-band Selection of z ~ 5 Quasar Candidates 135 5.4 Spectroscopy Data 140 5.4.1 Gemini/GMOS Observation 140 5.4.2 Magellan/IMACS Observation 142 5.4.3 Supplemental Spectroscopic Redshift Sample 143 5.4.4 Spectra of Nonquasar Objects 144 5.5 Results 148 5.5.1 Spectroscopic Identification of Quasars 148 5.5.2 Medium-band Color Selection and Its Efficiency 148 5.5.3 SED fitting and Redshift Measurements 151 5.5.4 Medium-band Photometric Redshift Accuracy 159 5.6 Implication on the QLF at z ~ 5 163 5.7 Summary 164 6 Conclusion 167 Bibliography 170Docto

    Si[1-x]C[x] ๋‹จ๊ฒฐ์ •๋ง‰์—์„œ ์น˜ํ™˜ํ˜•์ž๋ฆฌ ํƒ„์†Œ์˜ ์†์‹ค ๊ฑฐ๋™ ์—ฐ๊ตฌ

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    ํ•™์œ„๋…ผ๋ฌธ(์„์‚ฌ)--์„œ์šธ๋Œ€ํ•™๊ต ๋Œ€ํ•™์› :์žฌ๋ฃŒ๊ณตํ•™๋ถ€,2001.Maste

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    Thesis (doctoral)--์„œ์šธ๋Œ€ํ•™๊ต ๋Œ€ํ•™์› :์žฌ๋ฃŒ๊ณตํ•™๋ถ€,2004.Docto
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