论文标题
沿M33（HERM33ES）的主要轴的气体和灰尘冷却 - Herschel/PACS [CII]和[OI]观测值
Gas and dust cooling along the major axis of M33 (HerM33es) -- Herschel/PACS [CII] and [OI] observations
论文作者
论文摘要
M33是当地群体中富含气体的螺旋星系。我们研究了两个主要的气体冷却线与总红外（TIR）粉尘连续体之间的关系。我们使用[CII]和[OI]（63UM）和TIR的远红外线绘制了M33中气体和灰尘的发射。使用Herschel/PACS观察到线图。这些地图具有50％的分辨率，并沿其主要轴线形成〜370pc宽条纹，覆盖了明亮的HII区域的位置，但也以2kpc Galacto以2kpc Galacto的距离向南到北部5.7kpc的距离为2kpc galacto的距离。从Spitzer/MIPS以及PACS的70UM，100UM和160UM处的24UM连续发射的完整 - 全甲状腺图被合并，以获得TIR的图。 TIR和[CII]强度在两个以上的数量级上相关。 TIR的范围转化为G0的一系列远紫外发射（FUV），在平均银河辐射场的单位中观察到2至200。随着TIR的上升，BINNED [CII]/TIR比下降，散射较大但散射较低。经过改良的黑体（MBB）拟合连续发射用于估计尘埃表面密度和总气柱密度。在将其与光子统治区域（PDR）模型进行比较之前，将可能通过冷气的前景吸收进行校正。 [CII]/[OI]和（[CII]+[OI]）/TIR的大部分比与两个模型解决方案一致。中位比与n〜2x10^2 cm-3，g0〜60的一个溶液以及在n〜10^4 cm-3，g0〜1.5处的第二个低蛋白溶液一致。沿视线的大部分气体由低密度高粉状相表示，低光束填充因子〜1。但是，一小部分的气体可能由第二种溶液表示。
M33 is a gas rich spiral galaxy of the Local Group. We investigate the relationship between the two major gas cooling lines and the total infrared (TIR) dust continuum. We mapped the emission of gas and dust in M33 using the far-infrared lines of [CII] and [OI](63um) and the TIR. The line maps were observed with Herschel/PACS. These maps have 50pc resolution and form a ~370pc wide stripe along its major axis covering the sites of bright HII regions, but also more quiescent arm and inter-arm regions from the southern arm at 2kpc galacto-centric distance to the south out to 5.7kpc distance to the north. Full-galaxy maps of the continuum emission at 24um from Spitzer/MIPS, and at 70um, 100um, and 160um from PACS were combined to obtain a map of the TIR. TIR and [CII] intensities are correlated over more than two orders of magnitude. The range of TIR translates to a range of far ultraviolet (FUV) emission of G0,obs~2 to 200 in units of the average Galactic radiation field. The binned [CII]/TIR ratio drops with rising TIR, with large, but decreasing scatter. Fits of modified black bodies (MBBs) to the continuum emission were used to estimate dust mass surface densities and total gas column densities. A correction for possible foreground absorption by cold gas was applied to the [OI] data before comparing it with models of photon dominated regions (PDRs). Most of the ratios of [CII]/[OI] and ([CII]+[OI])/TIR are consistent with two model solutions. The median ratios are consistent with one solution at n~2x10^2 cm-3, G0~60, and and a second low-FUV solution at n~10^4 cm-3, G0~1.5. The bulk of the gas along the lines-of-sight is represented by a low-density, high-FUV phase with low beam filling factors ~1. A fraction of the gas may, however, be represented by the second solution.
