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首页> 外文期刊>PASJ: Publications of the Astronomical Society of Japan >A molecular line survey toward the nearby galaxies NGC?1068, NGC?253, and IC?342 at 3?mm with the Nobeyama 45?m radio telescope: Impact of an AGN on 1 kpc scale molecular abundances
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A molecular line survey toward the nearby galaxies NGC?1068, NGC?253, and IC?342 at 3?mm with the Nobeyama 45?m radio telescope: Impact of an AGN on 1 kpc scale molecular abundances

机译：用Nobeyama 45？m射电望远镜在3？mm处向附近星系NGC？1068，NGC？253和IC？342进行的分子线调查：AGN对1 kpc尺度分子丰度的影响

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摘要

It is important to investigate the relationships between the power sources and the chemical compositions of galaxies in order to understand the scenario of galaxy evolution. We carried out an unbiased molecular line survey towards active galactic nucleus (AGN) host galaxy NGC1068, and prototypical starburst galaxies, NGC?253 and IC?342, with the Nobeyama 45?m telescope in the 3?mm band. The advantage of this line survey is that the obtained spectra have the highest angular resolution ever obtained with single-dish telescopes. In particular, the beam size of this telescope is ～15″–19″, which is able to separate spatially the nuclear molecular emission from that of the starburst ring (d?～?30″) in NGC?1068. We successfully detected approximately 23 molecular species in each galaxy, and calculated rotation temperatures and column densities. We estimate the molecular fractional abundances with respect to 13CO and CS molecules and compare them among three galaxies in order to investigate the chemical signatures of an AGN environment. As a result, we found clear trends in the abundances of molecules surrounding the AGN on a 1-kpc scale. HCN, H13CN, CN, 13CN, and HC3N are more abundant, and CH3CCH is deficient in NGC?1068 compared with the starburst galaxies. High abundances of HCN, H13CN, and HC3N suggest that the circumnuclear disk in NGC?1068 is in a high-temperature environment. The reason for the non-detection of CH3CCH is likely to be dissociation by high-energy radiation or less sublimation of a precursor of CH3CCH from grains.
机译：重要的是要研究电源与星系化学组成之间的关系，以便了解星系演化的情况。我们使用Nobeyama 45？m望远镜在3？mm波段对活动星系核（AGN）宿主星系NGC1068，原型星暴星系NGC？253和IC？342进行了无偏分子线调查。该线测量的优势在于，所获得的光谱具有单碟望远镜所获得的最高角度分辨率。特别是，该望远镜的光束尺寸为〜15“ –19”，可以在空间上将NGC？1068中的核分子发射与星爆环的发射（d？〜？30''）分开。我们成功地在每个星系中检测到大约23种分子，并计算了旋转温度和列密度。我们估计相对于13CO和CS分子的分子分数丰度，并在三个星系中进行比较，以调查AGN环境的化学特征。结果，我们发现围绕AGN的1kpc规模的分子丰度有明显的趋势。与星爆星系相比，HCN，H13CN，CN，13CN和HC3N含量更高，而CH3CCH的NGC？1068含量不足。 HCN，H13CN和HC3N的丰度很高，表明NGC？1068中的核周盘处于高温环境中。未检测到CH3CCH的原因可能是由于高能辐射引起的解离或CH3CCH前体从颗粒中的升华程度降低。

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