CATALOG OF NARROW Mg II ABSORPTION LINES IN THE BARYON OSCILLATION SPECTROSCOPIC SURVEY
CATALOG OF NARROW Mg II ABSORPTION LINES IN THE BARYON OSCILLATION SPECTROSCOPIC SURVEY
复制标题
DOI：
10.1088/0067-0049/221/2/32
复制
发表时间：
2015-12
期刊：
影响因子：
--
通讯作者：
Zhi-Fu Chen;Q. Gu;Yan-Mei Chen
中科院分区：
文献类型：
--
作者：
Zhi-Fu Chen;Q. Gu;Yan-Mei Chen
利用重子振荡巡天数据发布9类星体光谱（不包括斯隆数字巡天数据发布7的类星体光谱），我们在1250 Å（类星体静止框架）光谱数据区发现了狭窄的Mg ii λ2796, 2803吸收双重态，直到Mg ii λ2800发射线的红翼。我们的调查仅限于类星体光谱，其中位数信噪比⟨S / N⟩≥4 ？在测量的光谱区域中，得到了43260个类星体。我们共检测到18598个Mg ii吸收双态，0.2933≤zabs≤2.6529。约75%的吸收器在静止框架下的等效宽度为W r λ 2796≥1 Å ？>。约75%的吸收剂具有双重倍率（DR = W r λ 2796 / W r λ 2803 ?）>)在1≤DR≤2范围内，约3.2%不在1−σDR≤DR≤2 + σDR范围内。我们通过在光谱数据信噪比范围内检测到的Mg ii吸收重态的频率来表征检测的假阳性/阴性。S/N = 4.5极限的完备分数为53%，当S/N大于4.5时趋于完备。所有检测到的镁吸收体的红移数密度从z≈0.4适度增加到z≈1.5，这与宇宙恒星形成速率密度的演化相一致。将我们的研究限制在那些发射红移可以从窄发射线确定的类星体上，Mg ii吸收体的相对速度（β）具有复杂的分布，可能由三种类型的Mg ii吸收体组成：(1)宇宙干涉吸收体；(2)类星体宿主星系或星系团内的环境吸收体；(3)类星体流出吸收体。在减去宇宙介入吸收剂和环境吸收剂的贡献后，类星体流出吸收剂的β分布可能主要由类星体流出吸收剂贡献，其峰值在υ≈1500 km s−1处。这个峰值速度低于在c4吸收剂的统计分析中发现的2000 km s−1的值。
Using the Data Release 9 Quasar spectra from the Baryonic Oscillation Spectroscopic Survey, which does not include quasar spectra from the Sloan Digital Sky Survey Data Release 7, we detect narrow Mg ii λλ2796, 2803 absorption doublets in the spectral data redward of 1250 Å (quasar rest frame) until the red wing of the Mg ii λ2800 emission line. Our survey is limited to quasar spectra with a median signal-to-noise ratio ⟨ S / N ⟩ ≥ 4 ?> pixel−1 in the surveyed spectral region, resulting in a sample that contains 43,260 quasars. We have detected a total of 18,598 Mg ii absorption doublets with 0.2933 ≤ zabs ≤ 2.6529. About 75% of absorbers have an equivalent width at rest frame of W r λ 2796 ≥ 1 Å ?> . About 75% of absorbers have doublet ratios ( DR = W r λ 2796 / W r λ 2803 ?> ) in the range of 1 ≤ DR ≤ 2, and about 3.2% lie outside the range of 1 − σDR ≤ DR ≤ 2 + σDR. We characterize the detection false positives/negatives by the frequency of detected Mg ii absorption doublets in the limits of the S/N of the spectral data. The S/N = 4.5 limit is assigned a completeness fraction of 53% and tends to be complete when the S/N is greater than 4.5. The redshift number densities of all of the detected Mg ii absorbers moderately increase from z ≈ 0.4 to z ≈ 1.5, which parallels the evolution of the cosmic star formation rate density. Limiting our investigation to those quasars whose emission redshift can be determined from narrow emission lines, the relative velocities (β) of Mg ii absorbers have a complex distribution which probably consists of three classes of Mg ii absorbers: (1) cosmologically intervening absorbers; (2) environmental absorbers that reside within the quasar host galaxies or galaxy clusters; (3) quasar outflow absorbers. After subtracting contributions from cosmologically intervening absorbers and environmental absorbers, the β distribution of the Mg iiabsorbers might mainly be contributed by the quasar outflow absorbers and peaks at υ ≈ 1500 km s−1. This peak velocity is lower than the value of 2000 km s−1 found in statistical analysis of C iv absorbers.