The ALPINE–ALMA [C ii] Survey: The Infrared–Radio Correlation and Active Galactic Nucleus Fraction of Star-forming Galaxies at z ∼ 4.4

DOI：

10.3847/1538-4357/ac81c5

发表时间：

2022-08

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

Lu Shen;B. Lemaux;L. Lubin;Guilin Liu;M. Béthermin;M. Boquien;O. Cucciati;O. Le Fèvre;M. Talia;D. Vergani;G. Zamorani;A. Faisst;M. Ginolfi;C. Gruppioni;G. Jones;S. Bardelli;N. Hathi;A. Koekemoer;M. Romano;D. Schaerer;E. Zucca;Wenjuan Fang;Ben Forrest;R. Gal;D. Hung;E. Shah;Priti Staab;B. Vanderhoof;E. Ibar

我们展示了 66 个经光谱证实的 COSMOS 场中 4.4 < z < 5.9 处正常恒星形成星系 (SFG) 的射电特性，这些星系是在阿塔卡马大型毫米/亚毫米阵列大型计划（ALPINE）中检测到的 [C ii]。我们将这些星系（“C ii-detected-all”）分为低红移（“C ii-detected-lz”；<z> = 4.5）和高红移（“C ii-detected-hz”；<z> = 5.6）子样本，并对每个子样本从 X 射线到射电波段进行叠加多波长成像。在 C ii-检测到的所有样本和 lz 样本的堆叠 3 GHz 图像中检测到无线电信号，≥3σ。我们发现，我们的样本的红外-射电相关性（通过 q TIR 量化）低于正常 SFG 在 ∼3σ 显着性水平上的局部关系，并且与 2 < z < 5 的明亮亚毫米星系的局部关系大致一致。这些样本都没有在其堆叠光谱能量分布 (SED)、UV 光谱或堆叠 X 射线图像中显示出主要活动星系核活动的证据。尽管我们不能排除假设的光谱指数和应用的红外 SED 模板可能对造成这些差异的影响，但至少部分地，与较低红移相比，恒星形成的较低遮蔽部分可以减轻我们的堆叠 q TIR 与局部正常 SFG 之间的紧张关系。除了较老的恒星群之外，主要控制红外发射的尘埃堆积可能还没有足够的时间在这些星系中完全发生，而射电发射可以在更快的时间尺度上做出反应。因此，我们可能期望较低的 q TIR 是高红移 SFG 的一般特性。

We present the radio properties of 66 spectroscopically confirmed normal star-forming galaxies (SFGs) at 4.4 < z < 5.9 in the COSMOS field that were [C ii]-detected in the Atacama Large Millimeter/submillimeter Array Large Program to INvestigate [C ii] at Early times (ALPINE). We separate these galaxies (“C ii-detected-all”) into lower-redshift (“C ii-detected-lz”; 〈z〉 = 4.5) and higher-redshift (“C ii-detected-hz”; 〈z〉 = 5.6) subsamples, and stack multiwavelength imaging for each subsample from X-ray to radio bands. A radio signal is detected in the stacked 3 GHz images of the C ii-detected-all and lz samples at ≳3σ. We find that the infrared–radio correlation of our sample, quantified by q TIR, is lower than the local relation for normal SFGs at a ∼3σ significance level, and is instead broadly consistent with that of bright submillimeter galaxies at 2 < z < 5. Neither of these samples show evidence of dominant active galactic nucleus activity in their stacked spectral energy distributions (SEDs), UV spectra, or stacked X-ray images. Although we cannot rule out the possible effects of the assumed spectral index and applied infrared SED templates in causing these differences, at least partially, the lower obscured fraction of star formation than at lower redshift can alleviate the tension between our stacked q TIRs and those of local normal SFGs. It is possible that the dust buildup, which primarily governs the infrared emission, in addition to older stellar populations, has not had enough time to occur fully in these galaxies, whereas the radio emission can respond on a more rapid timescale. Therefore, we might expect a lower q TIR to be a general property of high-redshift SFGs.

The ALPINE–ALMA [C ii] Survey: The Infrared–Radio Correlation and Active Galactic Nucleus Fraction of Star-forming Galaxies at z ∼ 4.4–5.9

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