{"created":"2023-06-20T13:23:16.820936+00:00","id":4061,"links":{},"metadata":{"_buckets":{"deposit":"b5353b1c-ad71-4ae2-9d04-b63060322d93"},"_deposit":{"created_by":21,"id":"4061","owners":[21],"pid":{"revision_id":0,"type":"depid","value":"4061"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00004061","sets":["2:427:13"]},"author_link":["2234","2232","2233"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"松田, 桂子"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"マツタ, ケイコ"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2013-03-22"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（理学）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":"Some galaxies contain compact nuclei, which emit vast amounts of energy over the entire\nelectromagnetic spectrum from radio through gamma-rays, thus called active galactic nuclei\n(AGN). The powerful activity originates from the release of gravitational energy through accretion\nof material on to a supermassive black hole with a typical mass in the range of 106−9M⊙.\nSome of the gravitational energy is thermalized in the accretion disk to radiate ultraviolet and\nsoft X-ray emission. Some is channeled into the generation of energetic particles (or jets) and\nproduces X-ray through gamma-ray emission via inverse Compton scattering and radio through\nX-rays via synchrotron emission. This radiation from the vicinity of the black hole may heat\ncircumnuclear dust in the obscuring torus of clouds, which is believed to exist on parsec scales\noutside the accretion disk. The warm torus can then be a source of a strong infrared emission.\nAGN tend to show large variety in their observational properties, such as luminosities, optical\nline properties, radio brightness, variability, and so on. In spite of such apparent diversity, it\nis widely believed that the various AGN are intrinsically the same. Just a few parameters -\ninclination, accretion rate, and presence/absence of jets - may be responsible for the apparent\ndifferences. However, details of the geometry of the nuclei, especially of the torus, are poorly\nknown because their angular scales are very small and difficult to resolve spatially.\nThe main goal of this thesis is to study the geometry of the nuclear emission region based\nupon unbiased survey data gathered from multiple wavebands. For this purpose, I take two\napproaches; one is to explore the correlation between hard X-ray and infrared luminosities using\nunbiased samples systematically for each AGN type. The other is to analyze variability of midinfrared\nemission for individual sources and for each AGN type statistically using two all-sky\nsurvey catalogs. This is the first large-scale systematic study of mid-infrared variability in AGN,\nprobing timescales of several years separately for different types of AGN.\nFor the first approach, I used all-sky surveys conducted by Swift in the hard X-ray (> 10 keV)\nband and by AKARI in the infrared band. The Swift/Burst Alert Telescope all-sky survey\nprovides an unbiased, flux-limited selection of hard X-ray detected AGN. The hard X-ray band\nis rather insensitive to the photo-electric absorption due to the intervening clouds up to mildly\nCompton-thick (NH ∼1024 cm−2) column densities. In other words, the hard X-ray flux obtained\nby the survey reflects the intrinsic luminosity for all Compton-thin AGN and also for mildly\nCompton-thick ones, thus providing samples largely unbiased by obscuration. In the case of\ninfrared observations, high angular resolution is crucial in order to properly separate AGN from\nstellar emission in the host galaxy. However, this was not possible until the advent of recent\ntelescopes. The AKARI satellite completed an all-sky survey whose catalog was released just\nbefore the beginning of this research. This survey is several times more sensitive than previous\nones, and was carried out at a much higher angular resolution of the order of arcseconds. Crosscorrelating\nthe 22-month hard X-ray survey with the AKARI all-sky survey, I studied 158 AGN\ndetected by both instruments. I find a strong correlation for most AGN between the infrared\n(9, 18, and 90 μm) and hard X-ray (14–195 keV) luminosities, and quantified the correlation for\nvarious complete subsamples of AGN. Partial correlation analysis confirms that the correlation\nis intrinsic; that is, the correlation between the luminosities remains significant after removing\nthe contribution of redshift. Under the unification scheme of AGN, this result may be viewed\nas supporting clumpy torus models. The good one-to-one correlation between mid-infrared\nbolometric luminosities and hard X-ray ones for over four orders of magnitude indicates that\nthe covering factor of torus will decrease with the increase of the intrinsic luminosity. The\ncorrelation for radio galaxies has a slope and normalization identical to that for Seyfert 1s,\nwhere we have a direct view of the nuclear regions in both hard X-rays and infrared, implying\nsimilar hard X-ray/infrared emission processes in both. In contrast, sources with large Comptonthick\ncolumn densities show a large deficit in the hard X-ray band, because high gas column\ndensities in the torus diminish their apparent luminosities even in the hard X-ray band.\nOn the other hand, a few radio-loud sources (radio galaxies and blazars) show systematic deviations\ntoward higher X-ray luminosities in the correlations as compared to radio-quiet sources.\nOrigin of the broadband emission of radio galaxies is a matter of considerable debate. One possible\nexplanation of this deviation (i.e., excess X-rays) is the contribution of jets to the hard\nX-ray emission. Observations of flux variability can be useful for isolating the jet contribution,\nbecause strong and rapid fluctuations are characteristic of beamed jet emission. Useful hard\nX-ray variability data are not yet available, but such data have recently become available in\nthe mid-infrared band. Furthermore, mid-infrared variations can also potentially constrain the\ngeometry of the dusty torus by measuring the response of the torus to changes of the nucleus\nemission. This leads to the second topic of my thesis to study mid-infrared variability of AGN\nsystematically. I combine two mid-infrared all-sky surveys, i.e., the data released by AKARI\nand Wide-field Infrared Survey Explorer (WISE). WISE was launched about four years after\nAKARI and accomplished all-sky surveys with high sensitivity in several mid-infrared bands\n(particularly relevant for my work are the 12 and 22 μm bands). Because the bands observed\nby the two telescopes are slightly different, I calculated the flux ratio of WISE and AKARI\nafter subtracting the contribution of band differences, for which the spectral slope calculated\nfor each source was used. In addition, cross-calibration errors of the two telescopes are carefully\nexamined. I find significant mid-infrared variations in 3 sources, 2 blazars and 1 radio galaxy, in\neither or both of the 9 and 18 μm bands. Although no significant variations are detected from\nthe rest of the sources, low level variations may be hidden in statistical errors. Therefore, I tried\nto constrain the average sample variability for different AGN types, which was actually detected\nfrom Seyfert 1 in the 9 μm band. This is the first detection of variability from Seyfert 1 by using\ntwo mid-infrared all-sky surveys. I quantified the amplitudes of sample variability and found\nthat the amplitude reaches ∼10% in 4 years for Seyfert 1 in the 9 μm band. If this variability is\nexplained by the torus emission only, dust distribution in the torus should be compact, although\nother possibilities, such as jet contribution, cannot be excluded. Combining the results of the\nhard X-ray vs. mid-infrared correlations and mid-infrared variability, geometry and structure\nof the obscuring torus are discussed.","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第1584号 ","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"物理科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"11 宇宙科学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2012"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"MATSUTA, Keiko ","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-26"}],"displaytype":"simple","filename":"甲1584_要旨.pdf","filesize":[{"value":"504.4 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨","url":"https://ir.soken.ac.jp/record/4061/files/甲1584_要旨.pdf"},"version_id":"07501526-be10-4b69-9a02-2eab908a9799"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲1584_本文.pdf","filesize":[{"value":"1.8 MB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"本文","url":"https://ir.soken.ac.jp/record/4061/files/甲1584_本文.pdf"},"version_id":"78c8bd73-78ac-47f2-bc85-e60acc6055b8"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"A Systematic Study of Local Active Galactic Nuclei with Infrared and Hard X-ray All-Sky Surveys","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"A Systematic Study of Local Active Galactic Nuclei with Infrared and Hard X-ray All-Sky Surveys"},{"subitem_title":"A Systematic Study of Local Active Galactic Nuclei with Infrared and Hard X-ray All-Sky Surveys","subitem_title_language":"en"}]},"item_type_id":"1","owner":"21","path":["13"],"pubdate":{"attribute_name":"公開日","attribute_value":"2013-11-14"},"publish_date":"2013-11-14","publish_status":"0","recid":"4061","relation_version_is_last":true,"title":["A Systematic Study of Local Active Galactic Nuclei with Infrared and Hard X-ray All-Sky Surveys"],"weko_creator_id":"21","weko_shared_id":21},"updated":"2023-06-20T15:15:14.147772+00:00"}