A 33 GHz Survey of Local Major Mergers: Estimating the Sizes of the Energetically Dominant Regions from High-resolution Measurements of the Radio Continuum
A 33 GHz Survey of Local Major Mergers: Estimating the Sizes of the Energetically Dominant Regions from High-resolution Measurements of the Radio Continuum
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DOI：
10.3847/1538-4357/aa789a
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发表时间：
2017-05
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通讯作者：
L. Barcos-Muñoz;L. Barcos-Muñoz;A. Leroy;A. Evans;A. Evans;J. Condon;G. Privon;G. Privon;T. Thompson;L. Armus;T. Díaz-Santos;J. Mazzarella;David S. Meier;David S. Meier;E. Momjian;E. Murphy;J. Ott;D. Sanders;E. Schinnerer;S. Stierwalt;J. Surace;F. Walter
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作者：
L. Barcos-Muñoz;L. Barcos-Muñoz;A. Leroy;A. Evans;A. Evans;J. Condon;G. Privon;G. Privon;T. Thompson;L. Armus;T. Díaz-Santos;J. Mazzarella;David S. Meier;David S. Meier;E. Momjian;E. Murphy;J. Ott;D. Sanders;E. Schinnerer;S. Stierwalt;J. Surace;F. Walter
我们提出了甚大阵观测的33 GHz无线电连续辐射从22个本地超亮和亮红外（IR）星系（U/LIRGs）。这些观测的空间（角）分辨率为30-720 pc（0.″07-0.″67），在光谱的一部分，可能是光学薄。这使我们能够估计能量占优势的区域的大小。我们发现半光半径从30秒差距到1.7千秒差距。33 GHz的通量密度与红外辐射密切相关，我们将这些大小作为产生大部分能量的区域大小的指示。结合我们的33 GHz的尺寸与未解决的测量，我们估计红外光度和星星形成率单位面积和分子气体的表面和体积密度。这些量跨越了很宽的范围（4 dex），包括一些对任何星系测量的最高值（例如，).至少有13个源显示为康普顿厚（）。与以前的工作相一致，这些数据与正常盘星系的观测结果进行对比，表明星星形成率和分子气体表面密度之间存在非线性和可能的多值关系，尽管这一结果取决于采用的CO到H2的转换因子和我们的33 GHz大小适用于气体的假设。11个来源似乎超过了由辐射压和超新星反馈支持的星爆预测的光度表面密度;然而，我们注意到需要更详细的观测内部磁盘结构。具有较高表面亮度的U/LIRG表现出更强的[C ii] 158 μm缺陷，这与高能量密度驱动这种现象的建议一致。
We present Very Large Array observations of the 33 GHz radio continuum emission from 22 local ultraluminous and luminous infrared (IR) galaxies (U/LIRGs). These observations have spatial (angular) resolutions of 30–720 pc (0.″07–0.″67) in a part of the spectrum that is likely to be optically thin. This allows us to estimate the size of the energetically dominant regions. We find half-light radii from 30 pc to 1.7 kpc. The 33 GHz flux density correlates well with the IR emission, and we take these sizes as indicative of the size of the region that produces most of the energy. Combining our 33 GHz sizes with unresolved measurements, we estimate the IR luminosity and star formation rate per area and the molecular gas surface and volume densities. These quantities span a wide range (4 dex) and include some of the highest values measured for any galaxy (e.g., ). At least 13 sources appear Compton thick ( ). Consistent with previous work, contrasting these data with observations of normal disk galaxies suggests a nonlinear and likely multivalued relation between star formation rate and molecular gas surface density, though this result depends on the adopted CO-to-H2 conversion factor and the assumption that our 33 GHz sizes apply to the gas. Eleven sources appear to exceed the luminosity surface density predicted for starbursts supported by radiation pressure and supernova feedback; however, we note the need for more detailed observations of the inner disk structure. U/LIRGs with higher surface brightness exhibit stronger [C ii] 158 μm deficits, consistent with the suggestion that high energy densities drive this phenomenon.