小红点中的宿主星系紫外辐射与尘埃红化
Host Galaxy UV Emission and Dust Reddening in Little Red Dots
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中文总结 AI 辅助
本研究通过光谱拟合分析十三个小红点，发现其紫外发射主要源于宿主星系，且受尘埃红化影响，并根据断裂强度划分出极端子群体。
中文摘要 AI 辅助
小红点（LRDs）一直是大量分析的主题，旨在将其置于星系和黑洞演化的背景中。尽管针对LRDs静止光学发射的性质提出了几种可能的情景，但我们对紫外发射的理解仍存在争议。在此，我们旨在研究LRDs中紫外发射的起源。我们利用NIRSpec PRISM和中分辨率G235M与G395M光谱的组合，对十三个LRDs进行了发射线和连续谱拟合分析。我们分离并分析了来自LRDs中较大物理尺度的窄线发射。我们观察到，窄线巴耳末递减量通常大于情况B复合所预测的值，并且与紫外斜率和断裂强度大致相关，这提供了清晰的证据表明紫外发射起源于星系尺度，且其斜率受到尘埃红化的显著影响。SED拟合分析进一步表明，LRDs的紫外连续谱与尘埃衰减的恒星模板一致。最后，通过比较紫外斜率和巴耳末断裂强度，我们表明LRDs可以根据断裂强度进一步划分，使得典型的LRD光谱形状（强断裂强度（>3）和平坦的静止紫外连续谱）代表了最极端的子群体。我们的结果意味着，对于大多数LRDs，紫外发射主要来源于年轻的宿主星系，而特征性的光学发射可能是尘埃红化和本质上红色的吸积过程的组合所致。
英文摘要
Little Red Dots (LRDs) have been the subject of extensive analysis to place them within the context of galaxy and black hole evolution. Despite several proposed scenarios for the nature of the rest optical emission in LRDs, our understanding of the UV emission remains a matter of debate. Here, we aim to study the origin of the UV emission in LRDs. We conduct emission-line and continuum fitting analysis of thirteen LRDs using a combination of NIRSpec PRISM and medium-resolution G235M and G395M spectroscopy. We isolate and analyze the narrow-line emission arising from larger physical scales in LRDs. We observe that the narrow-line Balmer decrements are typically greater than those predicted for case B recombination and broadly correlated with both the UV slope and the break strength, providing clear evidence that the UV emission originates from galaxy scales and its slope is significantly affected by dust reddening. SED fitting analysis further shows that the UV continuum of LRDs is consistent with a dust attenuated stellar template. Finally, we show through a comparison of the UV slope and the Balmer break strength, that LRDs can be further divided based on break strength, such that the canonical LRD spectral shape (strong break strength ($>$ 3) and flat rest UV continuum) represents the most extreme sub-population. Our results imply that for most LRDs, the UV emission originates primarily from the young host galaxy, and that the characteristic optical emission may be due to a combination of dust reddening and intrinsically red accretion processes.
发表机构
- Dartmouth College（达特茅斯学院）
- Durham University（杜伦大学）
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