2011年度・東京大学・天文学教育研究センター・談話会

次回の談話会

第181回 2011/07/21(木) 15:30~16:30

柏川 伸成 氏 (国立天文台)

「AKB48 vs. NMB48 vs. SKE48, そして LAE45vs.LAE54」
"Completing the Census of Lyα Emitters at the Reionization Epoch"

We carried out extended spectroscopic confirmations of Lyα emitters (LAEs) at z = 6.5 and 5.7 
in the Subaru Deep Field. Now, the total number of spectroscopically confirmed LAEs is 45 and 54 
at z = 6.5 and 5.7, respectively, and at least 81% (70%) of our photometric candidates 
at z = 6.5 (5.7) have been spectroscopically identified as real LAEs. 
We made careful measurements of the Lyα luminosity, both photometrically and spectroscopically, 
to accurately determine the Lyα and rest-UV luminosity functions (LFs). 
The substantially improved evaluation of the Lyα LF at z = 6.5 shows an apparent deficit 
from z = 5.7 at least at the bright end, and a possible decline even at the faint end, 
though small uncertainties remain. The rest-UV LFs at z = 6.5 and 5.7 are in good agreement, 
at least at the bright end, in clear contrast to the differences seen in the Lyα LF. 
These results imply an increase in the neutral fraction of the intergalactic medium 
from z = 5.7 to 6.5. The rest-frame equivalent width (EW_0 ) distribution at z = 6.5 
seems to be systematically smaller than z = 5.7, and it shows an extended tail toward larger EW_0 . 
The bright end of the rest-UV LF can be reproduced from the observed Lyα LF and a reasonable 
EW_0 -UV luminosity relation. Integrating this rest-UV LF provides the first measurement of 
the contribution of LAEs to the photon budget required for reionization. The derived UV LF 
suggests that the fractional contribution of LAEs to the photon budget among Lyman break galaxies 
significantly increases toward faint magnitudes. Low-luminosity LAEs could dominate 
the ionizing photon budget, though this inference depends strongly on the uncertain 
faint-end slope of the Lyα LF.

趣旨

東京大学・天文学教育研究センターでは2003年4月から, 院生コロキウムに引き続き, 談話会を開いています.
第一線で活躍されている研究者の方々を講師にお招きし, 最先端の研究成果をお話しいただきます.
講師の方には, 大学院生の参加者のことも考慮し, レビュー的な側面も含めた上で, ご自身の研究紹介をお願いしています.

日時

場所

タイムテーブル

13:30-14:30院生コロキウム講義室
15:30-16:30談話会講義室
16:30-お茶の時間講義室横のお茶部屋~講師の方を交えて~

世話人

予定

#日付講演者 (所属)タイトル
1812011/07/21(木)柏川 伸成 氏 (国立天文台)「AKB48 vs. NMB48 vs. SKE48, そして LAE45vs.LAE54」」, "Completing the Census of Lyα Emitters at the Reionization Epoch"
1822011/07/28(木)上塚 貴史 氏 (東京大学・天文センター)Mid-infrared spectral monitoring toward AGB stars - Probing the formation of circumstellar dust -
-2011/09/01(木)眞山 聡 氏 (総研大)未定
-2011/09/29(木)西澤 淳 氏 (東京大学・IPMU)未定

終了した談話会

#日付講演者 (所属)タイトル
1772011/05/19(木)田村 陽一 氏 (東京大学・天文センター)「ASTE搭載用超伝導転移端センサ型ボロメータカメラとALMA初期科学運用」
1782011/06/16(木)Michael Richmond 氏 (Rochester Institute of Technology)"Looking for eclipsing RR Lyr stars in the MACHO database"
1792011/06/30(木)田中 賢幸 氏 (東京大学・IPMU)"A new method to identify AGNs and the nature of low-luminosity AGNs"
1802011/07/07(木)橋本 哲也 氏 (国立天文台)"A hint of AGN feedback: Shock heating of ISM induced by a jet in NGC 1068"

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