A sample of metal-poor galaxies identified from the LAMOST spectral survey  

作　　者：Yu-Long Gao Jian-Hui Lian Xu Kong Ze-Sen Lin Ning Hu Hai-Yang Liu En-Ci Wang Zi-Huang Cao Yong-Hui Hou Yue-Fei Wang Yong Zhang 

机构地区：[1]CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Scienceand Technology of China, Hefei 230026, China [2]School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, China [3]Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences,Beijing 100012, China [4]Nanjing Institute of Astronomical Optics & Technology, National Astronomical Observatories, Chinese Academyof Sciences, Nanjing 210042, China

出　　处：《Research in Astronomy and Astrophysics》2017年第5期17-30,共14页天文和天体物理学研究（英文版）

基　　金：Funding for the project has been provided by the National Development and Reform Commission;supported by the Strategic Priority Research Program “The Emergence of Cosmological Structures” of the Chinese Academy of Sciences (No. XDB09000000);the National Basic Research Program of China (973 Program) (2015CB857004);the National Natural Science Foundation of China (NSFC, Nos. 11225315, 1320101002, 11433005 and 11421303)

摘　　要：We present a sample of 48 metal-poor galaxies at z 〈 0.14 selected from 92 510 galaxies in the LAMOST survey. These galaxies are identified by their detection of the auroral emission line[OⅢ]λ4363 above the 3σ level, which allows a direct measurement of electron temperature and oxygen abundance. The emission line fluxes are corrected for internal dust extinction using the Balmer decrement method. With electron temperature derived from [OⅢ]λλ4959, 5007/[OⅢ]λ4363 and electron density from [SⅡ]λ6731/[SⅡ]λ6717, we obtain the oxygen abundances in our sample which range from 12 ＋ log（O/H） = 7.63（0.09 Z_⊙） to 8.46（0.6 Z_⊙）. We find an extremely metal-poor galaxy with 12 ＋ log（O/H） = 7.63 ± 0.01. With multiband photometric data from FUV to NIR and Hαmeasurements, we also determine the stellar masses and star formation rates, based on the spectral energy distribution fitting and Hα luminosity, respectively. We find that our galaxies have low and intermediate stellar masses with 6.39 ≤ log（M/M_⊙） ≤ 9.27, and high star formation rates（SFRs） with-2.18 ≤ log（SFR/M_⊙yr^（-1）） ≤ 1.95. We also find that the metallicities of our galaxies are consistent with the local T_e-based mass-metallicity relation, while the scatter is about 0.28 dex. Additionally,assuming the coefficient of α = 0.66, we find most of our galaxies follow the local mass-metallicity-SFR relation, but a scatter of about 0.24 dex exists, suggesting the mass-metallicity relation is weakly dependent on SFR for those metal-poor galaxies.We present a sample of 48 metal-poor galaxies at z 〈 0.14 selected from 92 510 galaxies in the LAMOST survey. These galaxies are identified by their detection of the auroral emission line[OⅢ]λ4363 above the 3σ level, which allows a direct measurement of electron temperature and oxygen abundance. The emission line fluxes are corrected for internal dust extinction using the Balmer decrement method. With electron temperature derived from [OⅢ]λλ4959, 5007/[OⅢ]λ4363 and electron density from [SⅡ]λ6731/[SⅡ]λ6717, we obtain the oxygen abundances in our sample which range from 12 ＋ log（O/H） = 7.63（0.09 Z_⊙） to 8.46（0.6 Z_⊙）. We find an extremely metal-poor galaxy with 12 ＋ log（O/H） = 7.63 ± 0.01. With multiband photometric data from FUV to NIR and Hαmeasurements, we also determine the stellar masses and star formation rates, based on the spectral energy distribution fitting and Hα luminosity, respectively. We find that our galaxies have low and intermediate stellar masses with 6.39 ≤ log（M/M_⊙） ≤ 9.27, and high star formation rates（SFRs） with-2.18 ≤ log（SFR/M_⊙yr^（-1）） ≤ 1.95. We also find that the metallicities of our galaxies are consistent with the local T_e-based mass-metallicity relation, while the scatter is about 0.28 dex. Additionally,assuming the coefficient of α = 0.66, we find most of our galaxies follow the local mass-metallicity-SFR relation, but a scatter of about 0.24 dex exists, suggesting the mass-metallicity relation is weakly dependent on SFR for those metal-poor galaxies.

关 键 词：galaxies： abundances -- galaxies： evolution -- galaxies： starburst -- star formation 

分 类 号：P152[天文地球—天文学]