THE STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES. III. CHARACTERIZING QUENCHING IN LOW-MASS GALAXIES
THE STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES. III. CHARACTERIZING QUENCHING IN LOW-MASS GALAXIES
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DOI：
10.1088/0004-637x/804/2/136
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发表时间：
2015-03
期刊：
影响因子：
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通讯作者：
D. Weisz;A. Dolphin;E. Skillman;J. Holtzman;K. Gilbert;J. Dalcanton;B. Williams
中科院分区：
文献类型：
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作者：
D. Weisz;A. Dolphin;E. Skillman;J. Holtzman;K. Gilbert;J. Dalcanton;B. Williams
我们探索了低质量星系的猝灭(10.4 > M−> ？> 108 m⊙？>)作为回溯时间的函数，利用38个本星系群的恒星形成历史（SFHs）。sfh是通过分析哈勃太空望远镜/宽视场行星照相机2的存档图像中已分辨恒星群的彩色星等图得出的。我们发现：(1)低质量星系比高质量星系更早猝灭；(2) R的内部？>，卫星当前与大质量宿主的距离与其熄灭时间之间没有相关性；(3) M31和银河系卫星（MW）的猝灭时间存在系统差异，尽管M31矮星的样本量和SFHs的不确定性无法得出明确的结论。结合文献的结果，我们定性地考虑了在恒星质量（10.4 > ?）的~ 7指数上淬灭星系部分的红移演化（z = 0-1）。> m - ？bbbb10 11.5 ？bbbbm⊙？>)。所有星系的淬灭部分一般都在增加，在所有红移中，质量最低和质量最高的星系都表现出最大的淬灭部分。相比之下，M -百科~ ？> 108-1010 m⊙？>的淬火分数最低。我们认为这样的中等质量星系是最不容易熄灭的。最后，我们将我们的猝灭时间与与MW相关的低质量星系的落入时间预测进行了比较。我们发现一些质量最低的卫星（例如，CVn II, Leo IV）可能在坠落前已经被淬灭，而质量较高的卫星（例如，Leo I, Fornax）通常在坠落后淬灭~ 1-4 Gyr。
We explore the quenching of low-mass galaxies (10 4 ≲ M ⋆ ≲ ?> 108 M ⊙ ?> ) as a function of lookback time using the star formation histories (SFHs) of 38 Local Group dwarf galaxies. The SFHs were derived by analyzing color–magnitude diagrams of resolved stellar populations in archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. We find: (1) lower-mass galaxies quench earlier than higher-mass galaxies; (2) inside of R virial ?> there is no correlation between a satellite’s current proximity to a massive host and its quenching epoch; and (3) there are hints of systematic differences in the quenching times of M31 and Milky Way (MW) satellites, although the sample size and uncertainties in the SFHs of M31 dwarfs prohibit definitive conclusions. Combined with results from the literature, we qualitatively consider the redshift evolution (z = 0–1) of the quenched galaxy fraction over ∼7 dex in stellar mass (10 4 ≲ ?> M ⋆ ≲ ?> 10 11.5 ?> M ⊙ ?> ). The quenched fraction of all galaxies generally increases toward the present, with both the lowest and highest-mass systems exhibiting the largest quenched fractions at all redshifts. In contrast, galaxies between M ⋆ ∼ ?> 108–1010 M ⊙ ?> have the lowest quenched fractions. We suggest that such intermediate-mass galaxies are the least efficient at quenching. Finally, we compare our quenching times with predictions for infall times for low-mass galaxies associated with the MW. We find that some of the lowest-mass satellites (e.g., CVn II, Leo IV) may have been quenched before infall, while higher-mass satellites (e.g., Leo I, Fornax) typically quench ∼1–4 Gyr after infall.