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arXiv 1906.08877astro-ph.GAastro-ph.HE
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光学诊断图中SDSS-FIRST源的射电光谱指数分布

Radio spectral index distribution of SDSS-FIRST sources across optical diagnostic diagrams

Michal Zajaček, Gerold Busch, Mónica Valencia-S., Andreas Eckart, Silke Britzen, Lars Fuhrmann, Jana Schneeloch, Nastaran Fazeli, Kevin C. Harrington, J. Anton Zensus

摘要:

关于星系核的活动如何调节其宿主的生长的详细了解仍然缺失。为了了解不同宿主中超大质量黑洞的吸积活动和吸积类型,必须研究大量河外源的射电光学性质。特别是,我们的目标是研究整个光发射线诊断图的无线电频谱指数的趋势,以寻找潜在的(反)相关性。为了实现这一目标,我们结合了流量密度从无线电第一次调查在$1.4\,{\rm GHz}$(与流量密度范围$10\,{\rm mJy} \leq F_{1.4} \leq 1000\,{\rm mJy}$)为209 SDSS源在中等红移$(0.04\leq z \leq 0.4)$与Effelsberg射电望远镜测量在$4.85\,{\rm GHz}$和$10.45\,{\rm GHz}$。有关光发射线比的信息来自SDSS-DR 7星表。使用Effelsberg数据,我们能够推断两点射电光谱指数分布的恒星形成星系,复合星系(与合并贡献的线发射的恒星形成和活动星系核活动),塞弗茨,和低电离窄发射区(LINER)星系。在研究陡峭,平坦和倒置源在光学诊断图中的分布时,我们发现我们的样本中有三类不同的无线电发射源:(i)具有陡峭无线电指数,高电离比和高无线电响度的源,(ii)具有平坦无线电指数,低电离比和中等无线电响度的源,(iii)具有倒置无线电指数,低电离比和低无线电响度的源。类(i),(ii),(iii)集群主要沿过渡Seyfert线性源的BPT图。我们将这些群体解释为经常性核喷流活动的结果。

英文摘要:

A detailed understanding of how the activity of a galactic nucleus regulates the growth of its host is still missing. To understand the activity and the types of accretion of supermassive black holes in different hosts, it is essential to study radio-optical properties of a large sample of extragalactic sources. In particular, we aim at studying the radio spectral index trends across the optical emission line diagnostic diagrams to search for potential (anti)correlations. To this goal, we combine flux densities from the radio FIRST survey at $1.4\,{\rm GHz}$ (with the flux density range $10\,{\rm mJy} \leq F_{1.4} \leq 1000\,{\rm mJy}$) for 209 SDSS sources at intermediate redshift $(0.04\leq z \leq 0.4)$ with the Effelsberg radiotelescope measurements at $4.85\,{\rm GHz}$ and $10.45\,{\rm GHz}$. The information about the optical emission-line ratios is obtained from the SDSS-DR7 catalogue. Using the Effelsberg data, we were able to infer the two-point radio spectral index distributions for star-forming galaxies, composite galaxies (with a combined contribution to the line emission from the star-formation and AGN activity), Seyferts, and low ionization narrow emission region (LINER) galaxies. While studying the distribution of steep, flat, and inverted sources across optical diagnostic diagrams, we found three distinct classes of radio emitters for our sample: (i) sources with steep radio index, high ionization ratio and high radio loudness, (ii) sources with flat radio index, lower ionization ratio and intermediate radio loudness, (iii) sources with inverted radio index, low ionization ratio and low radio loudness. The classes (i), (ii), (iii) cluster mainly along the transition from Seyfert to LINER sources in the BPT diagram. We interpret these groups as a result of the recurrent nuclear-jet activity.

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。

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