The search for active black holes in nearby low-mass galaxies using optical and mid-IR data
The search for active black holes in nearby low-mass galaxies using optical and mid-IR data
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使用光学和中红外数据寻找附近低质量星系中的活跃黑洞
DOI：
10.1093/mnras/stv2238
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发表时间：
2015
影响因子：
4.8
通讯作者：
K. Oh
中科院分区：
文献类型：
--
作者：
L. Sartori;K. Schawinski;E. Treister;B. Trakhtenbrot;M. Koss;M. Shirazi;K. Oh
我们研究了低质量星系中活动星系核的活动，这是一个重要的机制，可以揭示BH的形成和演化，以及它们与宿主星系的相互作用。在SDSS中，我们从48，000个邻近低质量星系（$M_{\rm \星星} \leq 10^{9.5}M_\odot$，$z < 0.1$）的母样本中识别出336个活动星系核候选者。我们使用经典的BPT图、基于HeII 4686线的类似光学发射线诊断和中红外色切来选择活动星系核。不同的标准选择具有不同物理性质（如恒星质量和光学颜色）的宿主星系，336个源中只有3个满足所有三个标准。这可能部分是由于选择偏差。由此产生的活动星系核分数为$\sim 0.7 \%$至少比估计的更大质量星系低一个数量级。在光学波长，基于HeII的活动星系核的选择似乎是更敏感的活动星系核托管在恒星形成的星系比经典的BPT图，至少在低质量的制度。一些光学选择的活动星系核候选者的X射线和射电数据似乎证实了它们的活动星系核性质，但需要后续观测来证实其余样本的活动星系核性质，特别是在中红外选择的情况下。我们的样本将是重要的，为未来的后续研究，旨在了解BH和宿主星系之间的关系，在低质量制度。
We investigated AGN activity in low-mass galaxies, an important regime that can shed light onto BH formation and evolution, and their interaction with their host galaxies. We identified 336 AGN candidates from a parent sample of $\sim 48,000$ nearby low-mass galaxies ($M_{\rm \star} \leq 10^{9.5}M_\odot$, $z < 0.1$) in the SDSS. We selected the AGN using the classical BPT diagram, a similar optical emission line diagnostic based on the HeII$\lambda$4686 line, and mid-IR color cuts. Different criteria select host galaxies with different physical properties such as stellar mass and optical color, and only 3 out of 336 sources fulfill all three criteria. This could be in part due to selection biases. The resulting AGN fraction of $\sim 0.7 \%$ is at least one order of magnitude below the one estimated for more massive galaxies. At optical wavelengths, the HeII-based AGN selection appears to be more sensitive to AGN hosted in star-forming galaxies than the classical BPT diagram, at least in the low-mass regime. The archival X-ray and radio data available for some of the optically selected AGN candidates seem to confirm their AGN nature, but follow-up observations are needed to confirm the AGN nature of the rest of the sample, especially in the case of mid-IR selection. Our sample will be important for future follow-up studies aiming to understand the relation between BHs and host galaxies in the low-mass regime.