AN INCREASING STELLAR BARYON FRACTION IN BRIGHT GALAXIES AT HIGH REDSHIFT
AN INCREASING STELLAR BARYON FRACTION IN BRIGHT GALAXIES AT HIGH REDSHIFT
复制标题
高红移明亮星系中恒星重子比例的增加
DOI：
--
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
S. Willner
中科院分区：
文献类型：
--
作者：
S. Finkelstein;Mimi Song;P. Behroozi;R. Somerville;C. Papovich;M. Milosavljevic;A. Dekel;D. Narayanan;M. Ashby;A. Cooray;G. Fazio;H. Ferguson;A. Koekemoer;B. Salmon;S. Willner
最近的观察表明，静止帧紫外光(UV)光度函数的特征光度在4<；z<；7处没有显著变化，约为M UV*∼−21。？>；我们研究了173muv<；−21星系(z=4-7)，分析了它们的恒星群和宿主晕质量，从而研究了这种明显的非演化。包括对静止标架的光学光进行约束的深度斯皮策成像，我们发现在z=4-7的MUV*和GT；星系具有相似的恒星质量log(M/M⊙)=9.6-9.9，因此对于这些高红移来说是相对大的。然而，与z=2-3时的明亮星系相比，z=4-7时的明亮星系质量更小，推测的年龄也更早，尽管这两个星系群在固定的尘埃衰减曲线下具有相似的恒星形成率和尘埃衰减水平。将这些明亮的z=4-7星系的丰度与来自BolhoiΛCDM模拟的晕质量函数进行匹配，表明∼M UV*>；星系中的典型晕质量从z=4时的log(Mh/M⊙)=11.9时减小到z=7时的log(Mh/M⊙)=11.4.因此，尽管我们研究的是多个红移中具有相似恒星质量的星系，但这些星系生活在较高红移的低质量晕中.∼Muv？>；星系中的恒星重子分数以宇宙平均Ωb/Ωm为单位，从z=4时的5.1%增加到z=7时的11.7%；这一演化在∼3σ水平上是显著的。这种上升并不符合对星系如何增长的简单预期，而是意味着某种影响，也许是反馈效率的下降，允许更高比例的可用重子转化为高红移的恒星。
Recent observations have shown that the characteristic luminosity of the rest-frame ultraviolet (UV) luminosity function does not significantly evolve at 4 < z < 7 and is approximately M UV * ∼ − 21 . ?> We investigate this apparent non-evolution by examining a sample of 173 bright, MUV < −21 galaxies at z = 4–7, analyzing their stellar populations and host halo masses. Including deep Spitzer/IRAC imaging to constrain the rest-frame optical light, we find that M UV * ?> galaxies at z = 4–7 have similar stellar masses of log(M/M⊙) = 9.6–9.9 and are thus relatively massive for these high redshifts. However, bright galaxies at z = 4–7 are less massive and have younger inferred ages than similarly bright galaxies at z = 2–3, even though the two populations have similar star formation rates and levels of dust attenuation for a fixed dust-attenuation curve. Matching the abundances of these bright z = 4–7 galaxies to halo mass functions from the Bolshoi ΛCDM simulation implies that the typical halo masses in ∼ M UV * ?> galaxies decrease from log(Mh/M⊙) = 11.9 at z = 4 to log(Mh/M⊙) = 11.4 at z = 7. Thus, although we are studying galaxies at a similar stellar mass across multiple redshifts, these galaxies live in lower mass halos at higher redshift. The stellar baryon fraction in ∼ M UV * ?> galaxies in units of the cosmic mean Ωb/Ωm rises from 5.1% at z = 4 to 11.7% at z = 7; this evolution is significant at the ∼3σ level. This rise does not agree with simple expectations of how galaxies grow, and implies that some effect, perhaps a diminishing efficiency of feedback, is allowing a higher fraction of available baryons to be converted into stars at high redshifts.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.
DOI：
10.1088/0004-637x/769/1/80
发表时间：
2013-05
期刊：
The Astrophysical Journal
影响因子：
--
作者：
M. Ashby;S. Willner;G. Fazio;J.-S. Huang;R. Arendt;P. Barmby;G. Barro;E. Bell;R. Bouwens
通讯作者：
M. Ashby;S. Willner;G. Fazio;J.-S. Huang;R. Arendt;P. Barmby;G. Barro;E. Bell;R. Bouwens