Observations of Cold Dust in Nearby Elliptical Galaxies
Observations of Cold Dust in Nearby Elliptical Galaxies
复制标题
附近椭圆星系中冷尘埃的观测
DOI：
10.1086/422795
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
N. Kuno
中科院分区：
文献类型：
--
作者：
L. Leeuw;A. Sansom;E. I. Robson;M. Haas;N. Kuno
光谱能量分布（SED）的分析，包括新的毫米远红外（FIR）的观测获得的连续仪器上的Nobeyama和詹姆斯克拉克麦克斯韦望远镜和红外空间天文台的7个附近（<45 Mpc）的FIR明亮的椭圆星系。这些分析与档案FIR和短波无线电数据从美国宇航局/IPAC河外数据库（NED）。射电到红外SED最适合于幂律加灰体模型，该模型是银河系中央区域直径为2.4 kpc，温度在~21和28 K之间，发射率指数为1.2，质量在~1.6到19 × 105 M之间的尘埃。的发射率指数是一致的尘埃组成的无定形硅酸盐和碳质颗粒先前模拟恒星加热的尘埃在银河系和其他附近的河外来源。使用更新的灰尘吸收系数，这种类型的灰尘，灰尘质量的估计是类似的，从早期的FIR数据单独确定的，即使后者的结果意味着更热的灰尘温度。通量和质量是一致的，新的FIR和亚毫米波数据估计的尘埃温度低于20 K的中央银河系区域内。对于这种表面亮度低的寒冷、弥漫的尘埃（如果存在的话），更严格的物理约束将需要斯皮策太空望远镜、SCUBA 2或阿尔马进行敏感的FIR到亚毫米观测。
Spectral energy distribution (SED) analyses that include new millimeter to far-infrared (FIR) observations obtained with continuum instruments on the Nobeyama and James Clerk Maxwell Telescopes and the Infrared Space Observatory are presented for seven nearby (<45 Mpc) FIR-bright elliptical galaxies. These are analyzed together with archival FIR and shortwave radio data obtained from the NASA/IPAC Extragalactic Database (NED). The radio to infrared SEDs are best-fitted by power law plus graybody models of dust residing in the central galactic regions within a 2.4 kpc diameter and with temperatures between ~21 and 28 K, emissivity index ≃2, and masses from ~1.6 to 19 × 105 M☉. The emissivity index is consistent with dust constituting amorphous silicate and carbonaceous grains previously modeled for stellar-heated dust observed in the Galaxy and other nearby extragalactic sources. Using updated dust absorption coefficients for this type of dust, dust masses are estimated that are similar to those determined from earlier FIR data alone, even though the latter results implied hotter dust temperatures. Fluxes and masses that are consistent with the new FIR and submillimeter data are estimated for dust cooler than 20 K within the central galactic regions. Tighter physical constraints for such cold, diffuse dust (if it exists) with low surface brightness will need sensitive FIR to submillimeter observations with the Spitzer Space Telescope, SCUBA2, or ALMA.