SSA22-AzTEC26场中CO发射体的特征研究
Characterizing CO Emitters in the SSA22-AzTEC26 Field
AI总结：
本研究通过分析SSA22-AzTEC26场的观测数据，探测并表征了四个CO发射体，揭示了盲目CO谱线搜索能够发现具有低比恒星形成率但气体储量丰富的大质量星系，并指出抑制恒星形成可能需要气体消耗以外的机制。
摘要：
我们报告了对在明亮亚毫米星系（SMG）SSA22-AzTEC26附近探测到的四个CO发射体的物理特征研究。我们分析了Atacama Large Millimeter/submillimeter Array（阿塔卡马大型毫米/亚毫米阵列）对SSA22-AzTEC26场的3、4和7波段观测数据。除了目标SMG外，我们在用300 km s$^{-1}$ FWHM高斯滤波器平滑的数据立方体中探测到四个信噪比$>5.2$的谱线发射体。所有四个源在1$\arcsec$内都有近红外（NIR）对应体。我们进行了从紫外到远红外（UV-to-FIR）的光谱能量分布建模，以推导测光红移和物理性质。基于测光红移，我们发现其中两个是红移为1.113和1.146的CO(2-1)发射，一个是$z=2.124$的CO(3-2)发射。这三个源是恒星质量$\gtrsim10^{10.5}M_\odot$的大质量星系，但具有不同的恒星形成水平。两个位于$z\sim1-2$恒星形成星系主序（MS）的散布范围内，而质量最大的星系显著低于MS。然而，所有三个源的气体分数都在MS标度关系的散布范围内。这表明盲目的CO谱线搜索可以探测到具有低比恒星形成率但仍拥有大量气体储库的大质量星系，并且它补充了目标巡天，暗示了后期气体获取以及除了气体消耗外还需要其他机制来抑制恒星形成。
英文摘要：
We report the physical characterization of four CO emitters detected near the bright submillimeter galaxy (SMG) SSA22-AzTEC26. We analyze the data from Atacama Large Millimeter/submillileter Array band 3, 4, and 7 observations of the SSA22-AzTEC26 field. In addition to the targeted SMG, we detect four line emitters with a signal-to-noise ratio $>5.2$ in the cube smoothed with 300 km s$^{-1}$ FWHM Gaussian filter. All four sources have NIR counterparts within 1$\arcsec$. We perform UV-to-FIR spectral energy distribution modeling to derive the photometric redshifts and physical properties. Based on the photometric redshifts, we reveal that two of them are CO(2-1) at redshifts of 1.113 and 1.146 and one is CO(3-2) at $z=2.124$. The three sources are massive galaxies with a stellar mass $\gtrsim10^{10.5}M_\odot$, but have different levels of star formation. Two lie within the scatter of the main sequence (MS) of star-forming galaxies at $z\sim1-2$, and the most massive galaxy lies significantly below the MS. However, all three sources have a gas fraction within the scatter of the MS scaling relation. This shows that a blind CO line search can detect massive galaxies with low specific star formation rates that still host large gas reservoirs and that it also complements targeted surveys, suggesting later gas acquisition and the need for other mechanisms in addition to gas consumption to suppress star formation.
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