ENHANCEMENT OF CO(3-2)/CO(1-0) RATIOS AND STAR FORMATION EFFICIENCIES IN SUPERGIANT H II REGIONS

被引：14

作者：

Miura, Rie E. ^{[1
,2
]}

Kohno, Kotaro ^{[3
,4
]}

Tosaki, Tomoka ^{[5
]}

Espada, Daniel ^{[1
,6
,7
]}

Hirota, Akihiko ^{[8
]}

Komugi, Shinya ^{[1
]}

Okumura, Sachiko K. ^{[9
]}

Kuno, Nario ^{[7
,8
]}

Muraoka, Kazuyuki ^{[10
]}

Onodera, Sachiko ^{[10
]}

Nakanishi, Kouichiro ^{[1
,6
,7
]}

Sawada, Tsuyoshi ^{[1
,6
]}

Kaneko, Hiroyuki ^{[11
]}

Minamidani, Tetsuhiro ^{[8
]}

Fujii, Kosuke ^{[1
,2
]}

Kawabe, Ryohei ^{[1
,6
]}

机构：

[1] Natl Astron Observ Japan, Mitaka, Tokyo 1818588, Japan

[2] Univ Tokyo, Dept Astron, Bunkyo Ku, Tokyo 1330033, Japan

[3] Univ Tokyo, Sch Sci, Inst Astron, Mitaka, Tokyo 1810015, Japan

[4] Univ Tokyo, Sch Sci, Res Ctr Early Univ, Bunkyo Ku, Tokyo 1130033, Japan

[5] Joetsu Univ Educ, Niigata 9438512, Japan

[6] Joint ALMA Observ, Santiago 7630355, Chile

[7] Grad Univ Adv Studies Sokendai, Dept Astron Sci, Mitaka, Tokyo 1810015, Japan

[8] Nobeyama Radio Observ, Nagano 3841805, Japan

[9] Japan Womens Univ, Fac Sci, Dept Math & Phys Sci, Bunkyo Ku, Tokyo 1128681, Japan

[10] Osaka Prefecture Univ, Sakai, Osaka 5998531, Japan

[11] Meisei Univ, Dept Phys, Tokyo 1918506, Japan

来源：

ASTROPHYSICAL JOURNAL | 2014年 / 788卷 / 02期

关键词：

galaxies: individual (M33); H II regions; ISM: clouds; radio lines: ISM; GIANT MOLECULAR CLOUDS; LARGE-MAGELLANIC-CLOUD; ALL-DISK SURVEY; NEARBY GALAXIES; HII-REGIONS; FORMATION LAW; SCHMIDT LAW; 30; DORADUS; DYNAMICAL EXPANSION; MASSIVE STAR;

D O I：

10.1088/0004-637X/788/2/167

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present evidence that super giant H II regions (GHRs) and other disk regions of the nearby spiral galaxy, M33, occupy distinct locations in the correlation between molecular gas, Sigma H-2, and the star formation rate surface density, Sigma(SFR). This result is based on wide-field and high-sensitivity CO(3-2) observations at 100 pc resolution. Star formation efficiencies (SFEs), defined as Sigma(SFR)/Sigma H-2, in GHRs are found to be similar to 1 dex higher than in other disk regions. The CO(3-2)/CO(1-0) integrated intensity ratio, R3-2/1-0, is also higher than the average over the disk. Such high SFEs and R3-2/1-0 can reach the values found in starburst galaxies, which suggests that GHRs may be the elements building up a larger-scale starburst region. Three possible contributions to high SFEs in GHRs are investigated: (1) the I-CO-N(H-2) conversion factor, (2) the dense gas fraction traced by R3-2/1-0, and (3) the initial mass function (IMF). We conclude that these starburst-like properties in GHRs can be interpreted by a combination of both a top-heavy IMF and a high dense gas fraction, but not by changes in the I-CO-N(H-2) conversion factor.

引用

页数：7

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