{"_buckets": {"deposit": "79af9f89-aa9e-46b6-ba47-97ecf9f467c2"}, "_deposit": {"id": "15851", "owners": [], "pid": {"revision_id": 0, "type": "depid", "value": "15851"}, "status": "published"}, "_oai": {"id": "oai:soar-ir.repo.nii.ac.jp:00015851"}, "item_6_biblio_info_6": {"attribute_name": "\u66f8\u8a8c\u60c5\u5831", "attribute_value_mlt": [{"bibliographicIssueDates": {"bibliographicIssueDate": "2002-04", "bibliographicIssueDateType": "Issued"}, "bibliographicIssueNumber": "4", "bibliographicPageEnd": "1863", "bibliographicPageStart": "1847", "bibliographicVolumeNumber": "123", "bibliographic_titles": [{"bibliographic_title": "ASTRONOMICAL JOURNAL"}]}]}, "item_6_description_20": {"attribute_name": "\u6284\u9332", "attribute_value_mlt": [{"subitem_description": "We present a modest survey of quasar metal line absorption systems at redshifts 2.3-4.5. Relatively high signal-to-noise ratio (similar to25 pixel(-1)) spectra of 18 quasars at 2 Angstrom FWHM resolution show many absorption systems with strong metal lines in the region redward of the Lyalpha emission lines. We conducted a systematic search and found 55 C IV doublets, 19 Si IV doublets, three Mg II doublets, and seven N v doublets. The present data alone hint that the number of C IV absorption doublets per unit redshift, N(z), decreases with increasing redshift for 2.3 \u003c z \u003c 4.5 but at only the 1-2 sigma level, for either an Einstein de Sitter model (Lambda = 0) or a flat universe with Lambda = 0.7. When we combine our sample with published data that extend to lower redshifts, we detect evolution at the 1-4 sigma level, depending on the cosmological model and the strength of the C IV lines. There are fewer C IV systems per unit z with increasing z, and the systems with stronger C IV lines evolve much faster. At z similar or equal to 2.4, C IV with W \u003e 0.3 Angstrom are approximately 55% of all C IV systems with W \u003e 0.15 Angstrom, but by z similar or equal to 4 that percentage is less than 37%. Similar conclusions were reached by Sargent, Boksenberg, \u0026 Steidel and by Steidel, primarily at lower redshifts. However, we measure approximately twice the density of C IV systems at 2.3 \u003c z \u003c 3.8 with W \u003e 0.15 Angstrom that was reported by Steidel. The probability that our sample and previous samples come from the same distribution is only similar to2%. But this could be a statistical accident because it is an a posteriori comparison. We believe that the systems that we report are real, and we have no other explanation for this difference. For Si IV absorption lines, there is a 1 sigma hint of evolution with the same sense. In contrast, Lyalpha and Mg II systems are known to show evolution of the opposite sense with more absorbers at larger redshifts. The physical cause of this difference may be a mixture of ionization and chemical evolution effects.", "subitem_description_type": "Abstract"}]}, "item_6_description_30": {"attribute_name": "\u8cc7\u6e90\u30bf\u30a4\u30d7\uff08\u30b3\u30f3\u30c6\u30f3\u30c4\u306e\u7a2e\u985e\uff09", "attribute_value_mlt": [{"subitem_description": "Article", "subitem_description_type": "Other"}]}, "item_6_description_5": {"attribute_name": "\u5f15\u7528", "attribute_value_mlt": [{"subitem_description": "ASTRONOMICAL JOURNAL. 123(4):1847-1863 (2002)", "subitem_description_type": "Other"}]}, "item_6_link_3": {"attribute_name": "\u4fe1\u5dde\u5927\u5b66\u7814\u7a76\u8005\u7dcf\u89a7\u3078\u306e\u30ea\u30f3\u30af", "attribute_value_mlt": [{"subitem_link_text": "Misawa, T", "subitem_link_url": "http://soar-rd.shinshu-u.ac.jp/profile/ja.ypchuUkV.html"}]}, "item_6_link_67": {"attribute_name": "WoS", "attribute_value_mlt": [{"subitem_link_text": "Web of Science", "subitem_link_url": "http://gateway.isiknowledge.com/gateway/Gateway.cgi?\u0026GWVersion=2\u0026SrcAuth=ShinshuUniv\u0026SrcApp=ShinshuUniv\u0026DestLinkType=FullRecord\u0026DestApp=WOS\u0026KeyUT=000174756400004"}]}, "item_6_publisher_4": {"attribute_name": "\u51fa\u7248\u8005", "attribute_value_mlt": [{"subitem_publisher": "UNIV CHICAGO PRESS"}]}, "item_6_relation_48": {"attribute_name": "DOI", "attribute_value_mlt": [{"subitem_relation_name": [{"subitem_relation_name_text": "10.1086/339313"}], "subitem_relation_type_id": {"subitem_relation_type_id_text": "http://dx.doi.org/10.1086/339313", "subitem_relation_type_select": "DOI"}}]}, "item_6_rights_62": {"attribute_name": "\u6a29\u5229", "attribute_value_mlt": [{"subitem_rights": "Copyright\u00a9 2002 The American Astronomical Society"}]}, "item_6_select_64": {"attribute_name": "\u8457\u8005\u7248\u30d5\u30e9\u30b0", "attribute_value_mlt": [{"subitem_select_item": "publisher"}]}, "item_6_source_id_35": {"attribute_name": "ISSN", "attribute_value_mlt": [{"subitem_source_identifier": "0004-6256", "subitem_source_identifier_type": "ISSN"}]}, "item_6_source_id_39": {"attribute_name": "NII ISSN", "attribute_value_mlt": [{"subitem_source_identifier": "0004-6256", "subitem_source_identifier_type": "ISSN"}]}, "item_6_source_id_40": {"attribute_name": "\u66f8\u8a8c\u30ec\u30b3\u30fc\u30c9ID", "attribute_value_mlt": [{"subitem_source_identifier": "AA00552749", "subitem_source_identifier_type": "NCID"}]}, "item_6_text_69": {"attribute_name": "wosonly authkey", "attribute_value_mlt": [{"subitem_text_value": "galaxies : abundances; galaxies : evolution; quasars : absorption lines"}]}, "item_6_text_70": {"attribute_name": "wosonly keywords", "attribute_value_mlt": [{"subitem_text_value": "MG-II ABSORPTION; HIGH-RESOLUTION; HIGH-REDSHIFT; EVOLUTION; SAMPLE; SPECTRA; QSOS; ALPHA"}]}, "item_6_textarea_68": {"attribute_name": "wosonly abstract", "attribute_value_mlt": [{"subitem_textarea_value": "We present a modest survey of quasar metal line absorption systems at redshifts 2.3-4.5. Relatively high signal-to-noise ratio (similar to25 pixel(-1)) spectra of 18 quasars at 2 Angstrom FWHM resolution show many absorption systems with strong metal lines in the region redward of the Lyalpha emission lines. We conducted a systematic search and found 55 C IV doublets, 19 Si IV doublets, three Mg II doublets, and seven N v doublets. The present data alone hint that the number of C IV absorption doublets per unit redshift, N(z), decreases with increasing redshift for 2.3 \u003c z \u003c 4.5 but at only the 1-2 sigma level, for either an Einstein de Sitter model (Lambda = 0) or a flat universe with Lambda = 0.7. When we combine our sample with published data that extend to lower redshifts, we detect evolution at the 1-4 sigma level, depending on the cosmological model and the strength of the C IV lines. There are fewer C IV systems per unit z with increasing z, and the systems with stronger C IV lines evolve much faster. At z similar or equal to 2.4, C IV with W \u003e 0.3 Angstrom are approximately 55% of all C IV systems with W \u003e 0.15 Angstrom, but by z similar or equal to 4 that percentage is less than 37%. Similar conclusions were reached by Sargent, Boksenberg, \u0026 Steidel and by Steidel, primarily at lower redshifts. However, we measure approximately twice the density of C IV systems at 2.3 \u003c z \u003c 3.8 with W \u003e 0.15 Angstrom that was reported by Steidel. The probability that our sample and previous samples come from the same distribution is only similar to2%. But this could be a statistical accident because it is an a posteriori comparison. We believe that the systems that we report are real, and we have no other explanation for this difference. For Si IV absorption lines, there is a 1 sigma hint of evolution with the same sense. In contrast, Lyalpha and Mg II systems are known to show evolution of the opposite sense with more absorbers at larger redshifts. 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