EVIDENCE OF VERY LOW METALLICITY AND HIGH IONIZATION STATE IN A STRONGLY LENSED, STAR-FORMING DWARF GALAXY AT z = 3.417
EVIDENCE OF VERY LOW METALLICITY AND HIGH IONIZATION STATE IN A STRONGLY LENSED, STAR-FORMING DWARF GALAXY AT z = 3.417
复制标题
在 z = 3.417 处的强透镜状恒星形成矮星系中存在非常低的金属度和高电离态的证据
DOI：
10.1088/2041-8205/788/1/l4
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
E. Merlin
中科院分区：
文献类型：
--
作者：
R. Amorín;A. Grazian;M. Castellano;L. Pentericci;A. Fontana;V. Sommariva;A. van der Wel;M. Maseda;E. Merlin
我们调查的气相金属丰度和莱曼连续（LyC）逃逸分数的强引力透镜，极端发射线星系在z = 3.417，J1000+ 0221 S，最近发现的坎德尔团队。我们从H+K波段大双筒望远镜（LBT）/LUCI中分辨率光谱中获得电离和金属敏感的发射线比。J1000+ 0221 S显示出高电离条件，这可以通过其增强的[O iii]/[O ii]和[O iii]/Hβ比率来证明。基于现有线比的强线方法表明，J1000+ 0221 S是一个极度贫金属的星系，金属丰度为12+log（O/H）< 7.44（Z < 0.05 Z），使其成为迄今为止发现的最贫金属的恒星形成星系之一。结合它的低恒星质量（2 × 108 M）和高星星形成率（5 M yr−1），J1000+ 0221 S的金属丰度与莱曼破裂星系在z = 3处追踪到的质量-金属丰度关系外推到低质量一致，但它比基本金属丰度关系在z = 2.5处预测的低0.55 dex。这些观测表明，一个快速增长的星系，可能是由大量原始气体的吸积提供的。此外，深LBT/LBC测光在UGR波段被用来获得限制的LyC逃逸分数，从而使我们能够探索的第一次制度的sub-L* 星系在z > 3。我们发现逃逸分数的1σ上限为23%，这给最近的理论模型增加了一个新的观测约束，预测在高z的亚L * 星系具有高逃逸分数，因此是宇宙再电离的原因。
We investigate the gas-phase metallicity and Lyman continuum (LyC) escape fraction of a strongly gravitationally lensed, extreme emission-line galaxy at z = 3.417, J1000+0221S, recently discovered by the CANDELS team. We derive ionization- and metallicity-sensitive emission-line ratios from H+K band Large Binocular Telescope (LBT)/LUCI medium resolution spectroscopy. J1000+0221S shows high ionization conditions, as evidenced by its enhanced [O iii]/[O ii] and [O iii]/Hβ ratios. Strong-line methods based on the available line ratios suggest that J1000+0221S is an extremely metal-poor galaxy, with a metallicity of 12+log (O/H) < 7.44 (Z < 0.05 Z☉), placing it among the most metal-poor star-forming galaxies at z ≳ 3 discovered so far. In combination with its low stellar mass (2 × 108 M☉) and high star formation rate (5 M☉ yr−1), the metallicity of J1000+0221S is consistent with the extrapolation of the mass–metallicity relation traced by Lyman-break galaxies at z ≳ 3 to low masses, but it is 0.55 dex lower than predicted by the fundamental metallicity relation at z ≲ 2.5. These observations suggest a rapidly growing galaxy, possibly fed by massive accretion of pristine gas. Additionally, deep LBT/LBC photometry in the UGR bands are used to derive a limit to the LyC escape fraction, thus allowing us to explore for the first time the regime of sub-L* galaxies at z > 3. We find a 1σ upper limit to the escape fraction of 23%, which adds a new observational constraint to recent theoretical models predicting that sub-L* galaxies at high-z have high escape fractions and thus are the responsible for the reionization of the universe.
DOI：
10.1088/0004-637x/783/1/45
发表时间：
2014-01
期刊：
The Astrophysical Journal
影响因子：
--
作者：
J. Almeida;A. B. Morales-Luis;C. Muñoz-Tuñón;D. Elmegreen;B. Elmegreen;J. I. D. A. D. Canarias-J.-I.-D.-A.-D.-Canarias-1388340798;La Laguna;Tenerife;Spain.;D. Astrof́isica;U. L. Laguna;D. Physics;Astronomy;Vassar College;Ny;USA.;Ibm Research Division;T. J. W. R. Center;S. O. Physics;U. S. Andrews;UK.
通讯作者：
J. Almeida;A. B. Morales-Luis;C. Muñoz-Tuñón;D. Elmegreen;B. Elmegreen;J. I. D. A. D. Canarias-J.-I.-D.-A.-D.-Canarias-1388340798;La Laguna;Tenerife;Spain.;D. Astrof́isica;U. L. Laguna;D. Physics;Astronomy;Vassar College;Ny;USA.;Ibm Research Division;T. J. W. R. Center;S. O. Physics;U. S. Andrews;UK.
马萨诸塞大学阿默斯特分校（美国）
DOI：
--
发表时间：
--
期刊：
影响因子：
--
作者：
通讯作者：
--