The IRAM M 33 CO(2–1) survey - A complete census of molecular gas out to 7 kpc
The IRAM M 33 CO(2–1) survey - A complete census of molecular gas out to 7 kpc
复制标题
IRAM M 33 CO(2–1) 调查 - 分子气体的完整普查，直至 7 kpc
DOI：
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
P. Werf
中科院分区：
文献类型：
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作者：
C. Druard;J. Braine;K. Schuster;Nathan Schneider;P. Gratier;S. Bontemps;M. Boquien;F. Combes;E. Corbelli;Christian Henkel;Christian Henkel;F. Herpin;C. Kramer;F. V. D. Tak;F. V. D. Tak;P. Werf
为了研究低金属丰度环境中的星际介质以及原子和分子成分之间的相互作用，我们提供了本星系群12 CO（J = 2-1）发射的完整高角度和光谱分辨率地图以及位置-位置-速度数据立方体。梅西耶33。它的金属丰度大约是太阳的一半，因此我们可以将其星际介质与银河系进行比较，主要变化是金属丰度和气体质量分数。数据的角分辨率为12″（~50 pc），光谱分辨率为2.6 km s-1，天线温度的平均和中值噪声水平为20 mK/通道。在12 CO（J = 1-0）谱线中也观察到沿长轴的径向切割沿着。CO数据立方体和集成的强度图是最佳的，当使用H i数据来定义基线窗口和CO排放的速度被集成。在构建这些地图、测试不同的窗口和基线选项以及调查误差光束拾取的影响时，都非常小心。CO（2-1）的总光度为2.8 × 107 K km s-1 pc 2，沿着内盘的旋臂，平均强度大约沿着一个尺度长度为2.1 kpc的指数盘下降。CO（2-1/1-0）强度比随半径的变化不明显，平均值约为0.8。使用N（H2）/ICO（1 - 0）= 4 × 1020 cm-2/（K km s-1）的转换因子，估计总分子气体质量为3.1 × 108 M，包括氦。通过从CO光谱中减去Hi峰的速度，将立方体中的CO光谱移动到零速度。堆叠这些光谱在整个磁盘产生一个CO线的半功率宽度为12.4公里秒-1。因此，原子和分子成分之间的速度色散非常低，独立地证明了在构建我们的地图中使用H i线的合理性。同心环的光谱叠加表明，CO线宽和可能的CO-H i速度色散在外盘减少。误差光束拾取器可以从Hi线峰值未达到10 K的区域明显地产生弱CO发射，使得在这些区域中实际上没有检测到CO。使用CO（2-1）发射来追踪分子气体，H2柱密度的概率分布函数在高于对数正态分布的高柱密度处显示出过量。
To study the interstellar medium and the interplay between the atomic and molecular components in a low-metallicity environment, we present a complete high angular and spectral resolution map and position-position-velocity data cube of the 12CO(J = 2-1) emission from the Local Group galaxy Messier 33. Its metallicity is roughly half-solar, such that we can compare its interstellar medium with that of the Milky Way with the main changes being the metallicity and the gas mass fraction. The data have a 12″ angular resolution (~50 pc) with a spectral resolution of 2.6 km s-1 and a mean and median noise level of 20 mK per channel in antenna temperature. A radial cut along the major axis was also observed in the 12CO(J = 1-0) line. The CO data cube and integrated intensity map are optimal when using H i data to define the baseline window and the velocities over which the CO emission is integrated. Great care was taken when building these maps, testing different windowing and baseline options, and investigating the effect of error beam pickup. The total CO(2-1) luminosity is 2.8 × 107 K km s-1 pc2, following the spiral arms in the inner disk, with an average decrease in intensity approximately following an exponential disk with a scale length of 2.1 kpc. There is no clear variation in the CO(2-1/1-0) intensity ratio with radius and the average value is roughly 0.8. The total molecular gas mass is estimated, using a N(H2) /ICO(1 - 0) = 4 × 1020cm-2/(K km s-1) conversion factor, to be 3.1 × 108 M⊙, including helium. The CO spectra in the cube were shifted to zero velocity by subtracting the velocity of the H i peak from the CO spectra. Stacking these spectra over the whole disk yields a CO line with a half-power width of 12.4 km s-1. As a result, the velocity dispersion between the atomic and molecular components is extremely low, independently justifying the use of the H i line in building our maps. Stacking the spectra in concentric rings shows that the CO linewidth and possibly the CO-H i velocity dispersion decrease in the outer disk. The error beam pickup could produce the weak CO emission apparently from regions in which the H i line peak does not reach 10 K, such that no CO is actually detected in these regions. Using the CO(2-1) emission to trace the molecular gas, the probability distribution function of the H2 column density shows an excess at high column density above a log-normal distribution.
DOI：
10.1088/0004-637x/779/1/42
发表时间：
2013-04
期刊：
The Astrophysical Journal
影响因子：
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作者：
E. Schinnerer;S. Meidt;J. Pety;A. Hughes;D. Colombo;S. García-Burillo;K. Schuster;G. Dumas;C. Dobbs;A. Leroy;C. Kramer;T. Thompson;M. Regan
通讯作者：
E. Schinnerer;S. Meidt;J. Pety;A. Hughes;D. Colombo;S. García-Burillo;K. Schuster;G. Dumas;C. Dobbs;A. Leroy;C. Kramer;T. Thompson;M. Regan
M33 的 PACS 和 SPIRE 光度计图：Herschel M33 扩展勘测 (HERM33ES) 的第一个结果
影响因子：
6.5
作者：
Kramer
通讯作者：
Kramer