一个射电明亮的局域小红点类比天体
A Radio-Bright Local Little Red Dot Analog
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中文总结 AI 辅助
该研究发现了一个射电明亮的局域小红点类比天体J2048，其射电光度远高于此前探测的同类天体，为研究早期宇宙小红点的射电特性提供了新的观测参考。
中文摘要 AI 辅助
詹姆斯·韦布空间望远镜在早期宇宙（红移z>4）中发现了大量小红点（LRDs），这类致密的红色发光源拥有快速增长的超大质量黑洞（SMBH），周围伴随同代的核星暴。LRDs的关键特性之一是未被探测到射电辐射，这种未探测可能源于它们距离遥远。研究LRDs射电特性的一种方法是搜索其局域类比天体的射电辐射，局域小红点（LLRD）星系是红移z<1、具有与LRDs类似特性的天体。我们报告了对LLRD类比天体J204837.26−002437.2（z=0.4332，简称J2048）的射电连续谱探测，这是继另外两个LLRD射电探测后的新增成果。J2048在3.0 GHz处的流量密度为3.0±0.2 mJy，其射电光度比之前的探测结果高两个数量级，谱指数α=-0.39±0.04，符合中等光厚同步辐射的特征。J2048的射电光度为1.2×10^41 erg s^-1，处于射电噪巨椭圆星系和类星体（射电光度范围为L_R=10^41-46 erg s^-1）的低端。与J2048相关的SMBH的预期射电光度估计约大一个数量级，表明其射电光度可能被强烈遮蔽。一个射电光度与J2048相似的早期宇宙（z>4）LRD，可通过甚大天线阵（VLA）经中等时长的积分探测到。
英文摘要
The James Webb Space Telescope revealed the existence in the early Universe ($z >$ 4) of large populations of little red dots (LRDs), compact red luminous sources that host rapidly growing supermassive black holes (SMBHs) surrounded by coeval nuclear starbursts. LRDs have defining properties, one of which is the absence of radio detections. LRDs could be radio-undetected because of their large distances. A way to investigate the radio properties of LRDs is to search for radio emission in their local analogs, the Local Little Red Dot (LLRD) galaxies at $z <$ 1 with analogous properties to LRDs. We report the radio continuum detection of the LLRD analog J204837.26${-}$002437.2 ($z$ = 0.4332, hereinafter J2048). This adds to the previous radio detection of two other LLRDs. However, with a flux density of 3.0$\pm$0.2 mJy at 3.0 GHz, J2048 is two orders of magnitude more radio luminous than the previous detections. The spectral index of $α$ = -0.39$\pm$0.04 is consistent with moderately optically-thick synchrotron emission. The radio luminosity of J2048 is $1.2 \times 10^{41}~ \mathrm{erg ~s^{-1}}$, in the lower end of the range defined by radio-loud giant elliptical galaxies and quasars of $L_R$ = $10^{41-46} ~\mathrm{erg ~s^{-1}}$. The expected radio luminosity of the SMBH associated with J2048 is estimated to be about an order of magnitude larger, suggesting that its radio luminosity could potentially be strongly dimmed. A cosmological ($z >$ 4) LRD with radio luminosity similar to that of J2048 would be detectable using the VLA with moderately long integrations.
