论文标题
Hubble Ultra Deep Field（VLASPECS）中的VLA-Alma光谱调查：Z = 2-3“主序列”星系的总冷气质量和CO线比率
VLA-ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (VLASPECS): Total Cold Gas Masses and CO Line Ratios for z=2-3 "Main Sequence" Galaxies
论文作者
论文摘要
使用NSF的Karl G. Jansky非常大的阵列（VLA），我们报告了CO（J = 1-0）排放的六个检测，Z = 2-3个星系中的一个上限最初在Atacama大型亚略微计/毫米/毫米阵列（Alma）eppassromoscic spectromoscic the Hubble ulta field（与Hubble Ulta teep）中（与HIBBLE ULPLA深度）中的高级co发射中检测到。从CO（J = 1-0）线强度，我们测量M_GAS的总冷分子气体质量= 2.4-11.6 x 10^10（alpha_co/3.6）msun。我们还测量了一个中间CO（j = 3-2）至R_31 = 0.84 +/- 0.26的CO（j = 1-0）线亮度温度比，而CO（j = 7-6）与CO（J = 1-0）的比率范围为R_71 <0.05至0.17。这些结果表明，基于在高红移（COLDZ）监测高的ASPEC和VLA CO的发光度密度的有限的，目前可用的样品（CO）（j = 1-0）选定的星系中，CO（J = 3-2）所选星系平均具有更高的CO线激发。这意味着，基于CO（J = 3-2）测量值对星系中冷气体宇宙密度的先前估计值应根据CO激发的假设平均修改〜= 2的因子。这种校正进一步改善了当前最佳现有的限制，从线扫描调查到宇宙历史上的冷气密度演变与隐含的特征气体耗尽时间之间的一致性。
Using the NSF's Karl G. Jansky Very Large Array (VLA), we report six detections of CO(J=1-0) emission and one upper limit in z=2-3 galaxies originally detected in higher-J CO emission in the Atacama Large submillimeter/Millimeter Array (ALMA) Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS). From the CO(J=1-0) line strengths, we measure total cold molecular gas masses of M_gas = 2.4-11.6 x 10^10 (alpha_CO/3.6) Msun. We also measure a median CO(J=3-2) to CO(J=1-0) line brightness temperature ratio of r_31 = 0.84 +/- 0.26, and a CO(J=7-6) to CO(J=1-0) ratio range of r_71 <0.05 to 0.17. These results suggest that CO(J=3-2) selected galaxies may have a higher CO line excitation on average than CO(J=1-0) selected galaxies, based on the limited, currently available samples from the ASPECS and VLA CO Luminosity Density at High Redshift (COLDz) surveys. This implies that previous estimates of the cosmic density of cold gas in galaxies based on CO(J=3-2) measurements should be revised down by a factor of ~=2 on average based on assumptions regarding CO excitation alone. This correction further improves the agreement between the best currently existing constraints on the cold gas density evolution across cosmic history from line scan surveys, and the implied characteristic gas depletion times.
