arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1412.7896astro-ph.GA
收藏

巨低亮星系核活动和恒星形成的射电连续谱研究

Studying the radio continuum from nuclear activity and star formation in Giant Low Surface Brightness Galaxies

Alka Mishra, N. G. Kantharia, M. Das, D. C. Srivastava, S. N. Vogel

摘要:

利用巨米波射电望远镜对7个低表面亮度(GLSB)巨星系进行了多频射电连续谱研究。GLSB星系是光学暗淡的,暗物质占主导地位的系统,进化不良,具有大的HI气体盘。我们的样本由GLSB星系组成,这些星系在其光谱中显示出核活动的特征。我们探测到所有七个星系核的无线电辐射。有五个星系的核光谱指数在0.12到-0.44之间,似乎是核心主导的;两个星系的光谱更陡。其中两个星系,UGC 2936和UGC 4422显示出明显的射电辐射。在我们对UGC 6614的610 MHz观测中,我们探测到了与射电强活动星系核(AGN)有关的射电瓣。波瓣的频谱指数为-1.06+/-0.12。根据射电辐射估算出的整个样本的恒星形成速率范围为0.15 ~ 3.6百万太阳年^{-1}。我们比较无线电图像与近紫外(NUV)图像从GALEX和近红外(NIR)图像从2 MASS。星系呈现出相对NUV、NIR和射电辐射的多样性,支持这些星系的恒星形成情景。四个星系被归类为集团成员,一个被归类为孤立星系。我们对这个样本的多波长研究表明,环境在这些星系的演化中起着重要的作用。

英文摘要:

We present a multifrequency radio continuum study of seven giant low surface brightness (GLSB) galaxies using the Giant Metrewave Radio Telescope (GMRT). GLSB galaxies are optically faint, dark-matter dominated systems that are poorly evolved and have large HI gas disks. Our sample consists of GLSB galaxies that show signatures of nuclear activity in their optical spectra. We detect radio emission from the nuclei of all the seven galaxies. Five galaxies have nuclear spectral indices that range from 0.12 to -0.44 and appear to be core-dominated; the two galaxies have a steeper spectrum. Two of the galaxies, UGC 2936 and UGC 4422 show significant radio emission from their disks. In our 610 MHz observations of UGC 6614, we detect radio lobes associated with the radio-loud active galactic nucleus (AGN). The lobes have a spectral index of -1.06+/-0.12. The star formation rates estimated from the radio emission, for the entire sample range from 0.15 to 3.6 M{solar} yr^{-1} . We compare the radio images with the near-ultraviolet (NUV) images from GALEX and near-infrared (NIR) images from 2MASS. The galaxies present a diversity of relative NUV, NIR and radio emission, supporting an episodic star formation scenario for these galaxies. Four galaxies are classified members of groups and one is classified as isolated. Our multiwavlength study of this sample suggests that the environment plays an important role in the evolution of these galaxies.

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。

↑