所有小红点都去哪了？z < 0.35的宽线天体中小红点类似体的丰度
Where did all the Little Red Dots go? The abundance of LRD analogues among objects with broad lines at $z < 0.35$
AI总结：
该研究在z < 0.35的SDSS宽线天体中搜寻本地小红点（LRD）类似体，发现9个类似体，表明LRDs在低红移处极为罕见，验证了搜寻方法的有效性。
AI中文摘要：
自詹姆斯·韦布空间望远镜发射以来，最令人困惑的发现之一是高红移处大量被称为“小红点”（LRDs）的源。LRDs的特征是具有宽的巴尔末发射线、致密形态以及静止帧光学波段的v型光谱能量分布（SED），其本质仍不明确。一个主要挑战是LRDs的高红移特性，这使得观测成本极高且难度大。寻找本地LRD类似体是揭示产生LRDs物理过程的关键一步，因为这可以利用众多设备进行成本更低的观测。在本文中，我们从SDSS的一个无偏母星表出发，该星表包含0 < z < 0.35范围内所有具有宽Hα或Hβ发射线的天体（包括星系和类星体），并结合存档的测光和光谱数据，开展本地LRD类似体的搜寻工作。我们发现，在宽线天体中，19%呈现v型SED。随后，我们选择SED能被修正黑体（MBB）很好描述的天体，共识别出9个本地LRD类似体，占所有宽线天体的0.08%。在仅匹配LRDs典型连续谱和发射线光度的天体中，5%呈现v型，0.37%呈现MBB型SED。我们找到了一个先前已确认的本地LRD类似体（即所谓的“蛋”），验证了我们方法的有效性。在其余8个类似体中，一个（J0302−0101）尽管明显嵌在星系核心中，但仍展现出LRD的所有特征；另一个天体性质模糊，其余6个天体的特殊SED可能有其他解释。我们的研究表明，LRDs在z < 0.35处极为罕见；即使不尝试匹配LRDs的致密性，我们也发现极少宽线天体具有LRD-like SED。
英文摘要：
One of the most puzzling discoveries since the launch of the James Webb Space Telescope is a numerous population of sources at high redshift nicknamed ``Little Red Dots'' (LRDs). Characterized by broad Balmer emission lines, compact morphologies and v-shaped spectral energy distributions (SEDs) in the rest-frame optical, the nature of LRDs remains elusive. A major challenge is the high redshift nature of LRDs, which makes observations very expensive and difficult. Finding local LRD analogues is a crucial step in unravelling the physical processes giving rise to LRDs, as cheaper observations with many facilities would become available. In this paper, we conduct a search for local LRD analogues by starting from an unbiased parent catalogue of all SDSS objects with broad H$α$ or H$β$ emission lines (both galaxies and quasars) at $0 < z < 0.35$, complemented by archival photometry and spectroscopy. We find that among broad-line objects, $19\%$ show a v-shaped SED. We then select objects whose SED is well described by a modified black body (MBB), and identify nine local LRD analogues, corresponding to $0.08\%$ of all objects with broad lines. Among only objects which match the typical continuum and emission line luminosities of LRDs, $5\%$ display a v-shape and $0.37\%$ display a MBB-like SED. We recover one previously-identified local LRD analogue (the so-called ``Egg''), validating our methodology. Among the other eight analogues, one (J0302$-$0101) shows all the hallmarks of an LRD despite being visibly embedded in the core of a galaxy; another object is ambiguous, and the remaining six may have alternative explanations for their peculiar SEDs. Our study highlights that LRDs are extremely rare at $z < 0.35$; we find very few objects with broad lines which have LRD-like SEDs, even without attempting to match the compactness of LRDs.
