A Very Large Array Survey of Luminous Extranuclear Star-forming Regions in Luminous Infrared Galaxies in GOALS
A Very Large Array Survey of Luminous Extranuclear Star-forming Regions in Luminous Infrared Galaxies in GOALS
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DOI：
10.3847/1538-4357/ab2872
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发表时间：
2019-06
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影响因子：
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通讯作者：
S. Linden;Y. Song;A. Evans;E. Murphy;L. Armus;L. Barcos-Muñoz;K. Larson;T. Díaz-Santos;G. Privon;J. Howell;J. Surace;V. Charmandaris;U. Vivian;A. Medling;J. Chu;E. Momjian
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作者：
S. Linden;Y. Song;A. Evans;E. Murphy;L. Armus;L. Barcos-Muñoz;K. Larson;T. Díaz-Santos;G. Privon;J. Howell;J. Surace;V. Charmandaris;U. Vivian;A. Medling;J. Chu;E. Momjian
我们提出了高分辨率的卡尔G。Jansky甚大阵对大天文台全天LIRG巡天中的发光和超亮红外星系（U/LIRG）的成像巡天。从68个星系的完整样本中，我们选择了25个亮红外星系（LIRGs），这些星系显示出足够灵敏度的分辨扩展发射，以成像超过核的星星形成活动的各个区域。利用宽带无线电连续谱观测，其采样频率范围从3到33 GHz，我们对位于星系核心13.2 μm之外的总共48个单独的恒星形成区域进行了光度和光谱指数的无干扰测量，这些恒星形成区域被确定为具有去投影的银河系中心半径（rG）。在这些“双核”区域测得的3-33 GHz光谱指数和33 GHz热分数的中位数分别为−0.51 ± 0.13和65% ± 11%。这些值与在正常恒星形成星系中匹配的空间尺度上进行的测量一致，并表明这些区域相对于本地U/LIRGs的中心更受热自由发射的支配。此外，我们发现这些区域的星星形成率中位数为1.11兆兆年−1，当我们把它们放在亚银河系恒星形成的主星系序列（SFMS）上时，我们发现它们偏离了它们的宿主星系的全球平均特定星星形成率。我们的结论是，虽然核星暴活动驱动LIRGs以上的SFMS，双核星星的形成仍然在一个更极端的方式进行相对于什么是在本地螺旋星系。
We present the first results of a high-resolution Karl G. Jansky Very Large Array imaging survey of luminous and ultra-luminous infrared galaxies (U/LIRGs) in the Great Observatories All-sky LIRG Survey. From the full sample of 68 galaxies, we have selected 25 luminous infrared galaxies (LIRGs) that show resolved extended emission at sufficient sensitivity to image individual regions of star formation activity beyond the nucleus. With wideband radio continuum observations, which sample the frequency range from 3 to 33 GHz, we have made extinction-free measurements of the luminosities and spectral indicies for a total of 48 individual star-forming regions identified as having deprojected galactocentric radii (rG) that lie outside the 13.2 μm core of the galaxy. The median 3–33 GHz spectral index and 33 GHz thermal fraction measured for these “extranuclear” regions is −0.51 ± 0.13 and 65% ± 11%, respectively. These values are consistent with measurements made on matched spatial scales in normal star-forming galaxies, and suggests that these regions are more heavily dominated by thermal free–free emission relative to the centers of local U/LIRGs. Further, we find that the median star formation rate derived for these regions is ∼1 M⊙ yr−1, and when we place them on the sub-galactic star-forming main sequence of galaxies (SFMS), we find they are offset from their host galaxies’ globally averaged specific star formation rates. We conclude that while nuclear starburst activity drives LIRGs above the SFMS, extranuclear star formation still proceeds in a more extreme fashion relative to what is seen in local spiral galaxies.