arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1606.07214astro-ph.GA
收藏

高红移星系中尘埃的问题性增长

The problematic growth of dust in high redshift galaxies

Andrea Ferrara, Serena Viti, Cecilia Ceccarelli

摘要:

通过气体物质的吸积而产生的尘埃增长被认为是增加星系中尘埃数量的主要过程。我们在这里表明,这一假设遇到了严重的困难,使其不适合解释所观察到的紫外和红外光谱性质的系统,特别是在高红移。尘埃在扩散ISM阶段的增长受到以下因素的阻碍:(a)吸积速度太慢;(b)尘埃温度太高;(c)库仑势垒有效地阻止了吸积。在分子云中,这些问题在很大程度上得到了缓解。粒子是冷的(但不低于CMB温度,(Tcmb = 20 K,红移z=6)。然而,在稠密的环境中,增生的物质形成冰水地幔,也许还有杂质。在云的寿命结束时,当颗粒返回到弥漫的ISM时,地幔立即被光解吸,从而消除了任何生长的记忆。我们的结论是,在高$z$衰减恒星光的尘埃必须是现成的星尘,主要产生于超新星喷出物。

英文摘要:

Dust growth via accretion of gas species has been proposed as the dominant process to increase the amount of dust in galaxies. We show here that this hypothesis encounters severe difficulties that make it unfit to explain the observed UV and IR properties of such systems, particularly at high redshifts. Dust growth in the diffuse ISM phases is hampered by (a) too slow accretion rates; (b) too high dust temperatures, and (c) the Coulomb barrier that effectively blocks accretion. In molecular clouds these problems are largely alleviated. Grains are cold (but not colder than the CMB temperature, (Tcmb = 20 K at redshift z=6). However, in dense environments accreted materials form icy water mantles, perhaps with impurities. Mantles are immediately photo-desorbed as grains return to the diffuse ISM at the end of the cloud lifetime, thus erasing any memory of the growth. We conclude that dust attenuating stellar light at high-$z$ must be ready-made stardust largely produced in supernova ejecta.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑