An ALMA Survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS Field: The Far-infrared/Radio Correlation for High-redshift Dusty Star-forming Galaxies
An ALMA Survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS Field: The Far-infrared/Radio Correlation for High-redshift Dusty Star-forming Galaxies
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DOI：
10.3847/1538-4357/abb77b
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发表时间：
2020-09
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通讯作者：
H. Algera;I. Smail;U. Dudzevičiūtė;A. Swinbank;S. Stach;J. Hodge;A. Thomson;O. Almaini;V. Arumugam;A. Blain;G. Calistro-Rivera;S. Chapman;Chian-Chou Chen;E. D. Cunha;D. Farrah;S. Leslie;D. Scott;D. V. D. Vlugt-D.-V.-D.-Vlugt-27732973;J. Wardlow;P. V. D. Werf
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作者：
H. Algera;I. Smail;U. Dudzevičiūtė;A. Swinbank;S. Stach;J. Hodge;A. Thomson;O. Almaini;V. Arumugam;A. Blain;G. Calistro-Rivera;S. Chapman;Chian-Chou Chen;E. D. Cunha;D. Farrah;S. Leslie;D. Scott;D. V. D. Vlugt-D.-V.-D.-Vlugt-27732973;J. Wardlow;P. V. D. Werf
利用阿塔卡马大型毫米波阵列从超深巡天场的SCUBA-2宇宙学遗产巡天图中选取了706个位于870 μm的亚毫米星系（smg）的射电特性进行了研究。我们在Karl G. Jansky Very Large Array 1.4 GHz观测中探测到273个bbbb4 σ的smg，其中在610 MHz巨型米波射电望远镜成像中额外探测到45个smg。我们通过参数qIR量化远红外/射电相关性（FIRRC），定义为远红外和射电亮度的对数比，并通过叠加分析包括射电未探测到的smg。我们确定了整个样本的中位数qIR = 2.20±0.03，与红移无关，这使得这些z ~ 2.5的尘埃恒星形成星系比正常恒星形成星系和局部超发光红外星系（ulrgs）的局部相关指数低0.44±0.04。与本地恒星形成源相比，缺乏红移演化和本地相关性的偏移都可能是高红移星暴星系中不同物理条件的结果。我们通过强磁场（B≥0.2 mG）、高星际介质（ISM）密度和次级宇宙射线产生的额外射电辐射的组合来解释偏移。虽然局部ulrgs可能具有相似的磁场强度，但我们发现它们的致密性，加上与smg相比更高的ISM密度，自然解释了为什么局部和高红移尘埃恒星形成星系遵循不同的FIRRC。总的来说，我们的发现将smg描绘成一个均匀的星系群，正如它们紧密且不进化的远红外/射电相关性所说明的那样。
We study the radio properties of 706 submillimeter galaxies (SMGs) selected at 870 μm with the Atacama Large Millimeter Array from the SCUBA-2 Cosmology Legacy Survey map of the Ultra Deep Survey field. We detect 273 SMGs at >4σ in deep Karl G. Jansky Very Large Array 1.4 GHz observations, of which a subset of 45 SMGs are additionally detected in 610 MHz Giant Metre-Wave Radio Telescope imaging. We quantify the far-infrared/radio correlation (FIRRC) through parameter qIR, defined as the logarithmic ratio of the far-infrared and radio luminosity, and include the radio-undetected SMGs through a stacking analysis. We determine a median qIR = 2.20 ± 0.03 for the full sample, independent of redshift, which places these z ∼ 2.5 dusty star-forming galaxies 0.44 ± 0.04 dex below the local correlation for both normal star-forming galaxies and local ultra-luminous infrared galaxies (ULIRGs). Both the lack of redshift evolution and the offset from the local correlation are likely the result of the different physical conditions in high-redshift starburst galaxies, compared to local star-forming sources. We explain the offset through a combination of strong magnetic fields (B ≳ 0.2 mG), high interstellar medium (ISM) densities and additional radio emission generated by secondary cosmic rays. While local ULIRGs are likely to have similar magnetic field strengths, we find that their compactness, in combination with a higher ISM density compared to SMGs, naturally explains why local and high-redshift dusty star-forming galaxies follow a different FIRRC. Overall, our findings paint SMGs as a homogeneous population of galaxies, as illustrated by their tight and nonevolving far-infrared/radio correlation.