The MOSDEF Survey: The Nature of Mid-infrared Excess Galaxies and a Comparison of IR and UV Star Formation Tracers at z ∼ 2
The MOSDEF Survey: The Nature of Mid-infrared Excess Galaxies and a Comparison of IR and UV Star Formation Tracers at z ∼ 2
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MOSDEF 巡天：中红外多余星系的性质以及 z 〜 2 处红外和紫外恒星形成示踪剂的比较
DOI：
10.3847/1538-4357/aad3c8
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
T. Zick
中科院分区：
文献类型：
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作者：
Mojegan Azadi;A. Coil;J. Aird;I. Shivaei;N. Reddy;A. Shapley;M. Kriek;W. Freeman;G. Leung;B. Mobasher;S. Price;R. Sanders;B. Siana;T. Zick
我们使用MOSFIRE深度演化场（MOSDEF）调查对“MIR-excess”星系的性质进行了分析，这些星系的恒星形成率（SFRs）是从中红外（MIR）数据推断出来的，相对于从尘埃校正的紫外线数据估计的恒星形成率（SFRs）大大提高。我们使用了来自MIPS/Spitzer的24 μm（静止帧8 μm）的1.40 < z < 2.61的活动星系核（agn）样本约200个星系。我们发现，mir -过剩星系的识别在很大程度上取决于用于估计红外光度的方法（），并校正紫外线的尘埃衰减。我们发现，从观测到的24 μm通量中推断出的SFR，使用基于局部星系的光度相关模板，在z ~ 2星系中大大高估了。通过包括赫歇尔观测和使用与恒星质量无关、与亮度无关的方法，我们获得了更可靠的SFR估计和更低比例的mir -过剩星系。一旦考虑到恒星质量选择偏差，我们确定约24%的星系是MIR过剩。然而，在MIR过量的星系中，与MIR正常的星系相比，MIR过量的本征分数并没有升高，这表明MIR过量的本征分数可能更低。在MOSDEF中使用x射线、红外和光学选择的agn，我们没有发现相对于mir -正常星系，mir -过量星系中agn的患病率更高。对未检测到的x射线星系的叠加分析并没有显示出相对于mir -正常星系，mir -过量星系的光谱更硬。我们的分析表明，AGN活性并不是MIR过量的主要原因，相反，这可能是由于多环芳烃排放的增加。
We present an analysis using the MOSFIRE Deep Evolution Field (MOSDEF) survey on the nature of “MIR-excess” galaxies, which have star formation rates (SFRs) inferred from mid-infrared (MIR) data that are substantially elevated relative to those estimated from dust-corrected UV data. We use a sample of ∼200 galaxies and active galactic nuclei (AGNs) at 1.40 < z < 2.61 with 24 μm detections (rest-frame 8 μm) from MIPS/Spitzer. We find that the identification of MIR-excess galaxies strongly depends on the methodologies used to estimate IR luminosity ( ) and to correct the UV light for dust attenuation. We find that extrapolations of the SFR from the observed 24 μm flux, using luminosity-dependent templates based on local galaxies, substantially overestimate in z ∼ 2 galaxies. By including Herschel observations and using a stellar-mass-dependent, luminosity-independent , we obtain more reliable estimates of the SFR and a lower fraction of MIR-excess galaxies. Once stellar-mass selection biases are taken into account, we identify ∼24% of our galaxies as MIR excess. However, is not elevated in MIR-excess galaxies compared to MIR-normal galaxies, indicating that the intrinsic fraction of MIR excess may be lower. Using X-ray-, IR-, and optically selected AGNs in MOSDEF, we do not find a higher prevalence for AGNs in MIR-excess galaxies relative to MIR-normal galaxies. A stacking analysis of X-ray-undetected galaxies does not reveal a harder spectrum in MIR-excess galaxies relative to MIR-normal galaxies. Our analysis indicates that AGN activity does not contribute substantially to the MIR excess and instead implies that it is likely due to the enhanced polycyclic aromatic hydrocarbon emission.