z -GAL: A NOEMA spectroscopic redshift survey of bright Herschel galaxies III. Physical properties
z -GAL: A NOEMA spectroscopic redshift survey of bright Herschel galaxies III. Physical properties
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z -GAL：明亮赫歇尔星系的 NOEMA 光谱红移巡天 III。
DOI：
10.1051/0004-6361/202346803
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发表时间：
2023
影响因子：
6.5
通讯作者：
Berta S
中科院分区：
文献类型：
--
作者：
Berta S
Z-GAL巡天利用IRAM北方扩展毫米波阵观测了137个明亮的赫歇尔选择目标，目的是测量它们的红移并研究它们的性质。其中一些已被分解为多个来源。因此，已经测量了165个星系在0.8 <z<6.5范围内的鲁棒光谱红移。 在本文中，我们分析了z-GAL源的毫米光谱，使用它们的连续谱和线发射来推导它们的物理性质。每个源至少检测到两条谱线，包括12 CO、[Cl]和H2O的跃迁。单个源的12 CO谱线比和谱线能量分布类似于当地的星爆。在七个源中，探测到了para-H2O（211−202）跃迁，并遵循亚毫米星系的IR与H2O光度关系。z-GAL源的分子气体质量来自它们的12 CO、[CI]和亚毫米尘埃连续排放。这三种示踪剂导致一致的结果，与12 CO相比，尘埃连续体显示出最大的散射。这些来源的气体-尘埃质量比是通过结合来自12 CO和尘埃连续体的信息计算的，其中值为107，类似于近太阳金属丰度的恒星形成星系。同样的综合分析导致耗尽的时间尺度在0.1和1.0 Gyr之间的范围内，这将z-GAL源之间的“主序列”的星星形成和恒星爆发的轨迹。最后，我们通过反演已知的气体标度关系，得出了恒星质量的第一个估计值--以可能的引力放大率为模：z-GAL样本被证实主要由恒星爆发组成，而其25%的成员位于恒星形成星系的主序列（±0.5 dex以内）。
Thez-GAL survey observed 137 brightHerschel-selected targets with the IRAM Northern Extended Millimeter Array, with the aim to measure their redshift and study their properties. Several of them have been resolved into multiple sources. Consequently, robust spectroscopic redshifts have been measured for 165 individual galaxies in the range 0.8 <z< 6.5. In this paper we analyse the millimetre spectra of thez-GAL sources, using both their continuum and line emission to derive their physical properties. At least two spectral lines are detected for each source, including transitions of12CO, [CI], and H2O. The observed12CO line ratios and spectral line energy distributions of individual sources resemble those of local starbursts. In seven sources the para-H2O (211−202) transition is detected and follows the IR versus H2O luminosity relation of sub-millimetre galaxies. The molecular gas mass of thez-GAL sources is derived from their12CO, [CI], and sub-millimetre dust continuum emission. The three tracers lead to consistent results, with the dust continuum showing the largest scatter when compared to12CO. The gas-to-dust mass ratio of these sources was computed by combining the information derived from12CO and the dust continuum and has a median value of 107, similar to star-forming galaxies of near-solar metallicity. The same combined analysis leads to depletion timescales in the range between 0.1 and 1.0 Gyr, which place thez-GAL sources between the ‘main sequence’ of star formation and the locus of starbursts. Finally, we derived a first estimate of stellar masses – modulo possible gravitational magnification – by inverting known gas scaling relations: thez-GAL sample is confirmed to be mostly composed by starbursts, whereas ∼25% of its members lie on the main sequence of star-forming galaxies (within ±0.5 dex).