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arXiv 1403.7201astro-ph.GAastro-ph.CO
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亮红外星系NGC1614中心千秒差距区域的多波长观测

A multi-wavelength view of the central kiloparsec region in the Luminous Infrared Galaxy NGC1614

Rubén Herrero-Illana, Miguel Á. Pérez-Torres, Almudena Alonso-Herrero, Antxon Alberdi, Luis Colina, Andreas Efstathiou, Lorena Hernández-García, Daniel Miralles… 展开作者

Rubén Herrero-Illana, Miguel Á. Pérez-Torres, Almudena Alonso-Herrero, Antxon Alberdi, Luis Colina, Andreas Efstathiou, Lorena Hernández-García, Daniel Miralles-Caballero, Petri Väisänen, Christopher C. Packham, Vinesh Rajpaul, Albert A. Zijlstra

摘要:

亮红外星系NGC 1614拥有一个突出的恒星形成环。然而,在其中央~100 pc的主导发射机制的性质仍在争论中。我们提出了次弧秒角分辨率无线电,中红外,Pa-α,光学和X射线观测NGC 1614,旨在详细研究环核环和核区域。由甚大阵(VLA)和双子座/T-ReCS 8.7微米发射跟踪的8.4 GHz连续辐射,以及Pa-α线发射,在恒星形成环内显示出显着的形态相似性,这表明潜在的发射机制是紧密相关的。我们使用了HST/NICMOS Pa-α地图类似的分辨率,我们的无线电地图解开热自由和非热同步辐射的无线电发射,从中我们获得了内在的同步功率定律为每个单独的区域内的中央kpc的NGC 1614。射电环围绕着一个位于星系中心的相对微弱的陡谱源,这表明中心源不是由活动星系核提供动力,而是由一个紧凑的(r < 90 pc)星暴提供动力。钱德拉X射线数据还表明,中央kpc区域主要是由星暴活动,而不需要活动星系核的存在。我们还使用公开的红外数据模型拟合的光谱能量分布的星爆环和一个假定的活动星系核在NGC 1614。总之,我们的结论是,没有必要调用活动星系核来解释观测到的星系的辐射热特性。

英文摘要:

The Luminous Infrared Galaxy NGC1614 hosts a prominent circumnuclear ring of star formation. However, the nature of the dominant emitting mechanism in its central ~100 pc is still under debate. We present sub-arcsecond angular resolution radio, mid-infrared, Pa-alpha, optical, and X-ray observations of NGC1614, aimed at studying in detail both the circumnuclear ring and the nuclear region. The 8.4 GHz continuum emission traced by the Very Large Array (VLA) and the Gemini/T-ReCS 8.7 micron emission, as well as the Pa-alpha line emission, show remarkable morphological similarities within the star-forming ring, suggesting that the underlying emission mechanisms are tightly related. We used an HST/NICMOS Pa-alpha map of similar resolution to our radio maps to disentangle the thermal free-free and non-thermal synchrotron radio emission, from which we obtained the intrinsic synchrotron power-law for each individual region within the central kpc of NGC1614. The radio ring surrounds a relatively faint, steep-spectrum source at the very center of the galaxy, suggesting that the central source is not powered by an AGN, but rather by a compact (r < 90 pc) starburst. Chandra X-ray data also show that the central kpc region is dominated by starburst activity, without requiring the existence of an AGN. We also used publicly available infrared data to model-fit the spectral energy distribution of both the starburst ring and a putative AGN in NGC1614. In summary, we conclude that there is no need to invoke an AGN to explain the observed bolometric properties of the galaxy.

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