NGC 5044星系群中心星系中亚秒差距双超大质量黑洞的直接成像
Direct imaging of sub-parsec binary SMBHs in the central galaxy of the NGC 5044 group
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中文总结 AI 辅助
通过VLBA对NGC 5044的观测，直接成像了相距0.38秒差距的双活动星系核，为迄今最紧密的双AGN，并指出团中心椭圆星系是搜寻双超大质量黑洞的优选目标。
中文摘要 AI 辅助
双活动星系核（AGN）由位于同一星系中的两个超大质量黑洞（SMBHs）组成，它们同时吸积气体。这些系统是理解星系等级结构演化的关键，也是低频引力波（GW）实验的首要目标。然而，双AGN极为罕见：仅有少数在数百秒差距尺度上被确认，且只有一个秒差距尺度的双星——位于星系团中心的椭圆星系中——被可靠且直观地识别。亚秒差距双AGN是进入引力波阶段前的最后阶段，其直接成像迄今仍缺失。本文报告了对NGC 5044的甚长基线阵列（VLBA）观测，NGC 5044是X射线最亮星系群的中心星系。已知该星系表现出秒差距尺度的射电喷流，几乎与两次较老的AGN爆发正交。4.9、8.4、15.2和23.6 GHz的VLBA图像揭示了星系核心处两个致密、平谱且可变射电核，它们仅相距0.38秒差距，构成了迄今已知的直接成像双AGN中距离最近的一个，其紧密程度高出一个数量级。这一发现表明，较老的爆发可能由次级核的喷流驱动，而无需假设主喷流轴重新定向。更广泛地，与其他系统的比较表明，大质量、星系团中心的椭圆星系是搜寻双SMBHs的有前景的目标。
英文摘要
Binary active galactic nuclei (AGN) consist of two supermassive black holes (SMBHs) hosted in a single galaxy that are simultaneously accreting gas. These systems are key to understanding hierarchical galaxy evolution and represent prime targets for low-frequency gravitational wave (GW) experiments. However, binary AGN remain extremely rare: only a handful are confirmed at separations of a few hundred parsecs, and just one pc-scale binary - in an elliptical galaxy at the center of a galaxy cluster - has been securely and visually identified. Direct imaging of sub-parsec binary AGN, the final stage before the GW regime, has so far been missing. Here we report on Very Long Baseline Array (VLBA) observations of NGC 5044, the central galaxy of the X-ray brightest galaxy group. This galaxy is known to exhibit pc-scale radio jets nearly orthogonal to two older AGN outbursts. The 4.9, 8.4, 15.2, and 23.6 GHz VLBA images reveal two compact, flat-spectrum, and variable radio cores separated by just 0.38 parsec at the heart of the galaxy, forming the tightest directly imaged binary AGN known by an order of magnitude. This discovery suggests that the older outbursts may have been powered by jets from the secondary core, without invoking any reorientation of the primary jet axis. More broadly, comparison with other systems points to massive, cluster-central elliptical galaxies being promising targets to search for binary SMBHs.
发表机构
- Università di Bologna（博洛尼亚大学）
- Istituto Nazionale di Astrofisica（意大利国家天体物理研究所）
- Naval Research Laboratory（海军研究实验室）
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