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A CIGALE module tailored (not only) for low-luminosity active galactic nuclei
Astronomy & Astrophysics ( IF 5.4 ) Pub Date : 2024-12-13 , DOI: 10.1051/0004-6361/202450510
I. E. López, G. Yang, G. Mountrichas, M. Brusa, D. M. Alexander, R. D. Baldi, E. Bertola, S. Bonoli, A. Comastri, F. Shankar, N. Acharya, A. V. Alonso Tetilla, A. Lapi, B. Laloux, X. López López, I. Muñoz Rodríguez, B. Musiimenta, N. Osorio Clavijo, L. Sala, D. Sengupta

The spectral energy distribution (SED) of low-luminosity active galactic nuclei (LLAGN) presents unique challenges as the emission from these objects is comparable to the radiation from their host galaxy and the accretion physics involved is particularly complex. This study introduces a novel CIGALE module specifically designed to address these challenges. The module combines the empirical LXL12 μm relationship with physically motivated accretion models, such as advection-dominated accretion flows (ADAFs) and truncated accretion disks, providing a more accurate depiction of LLAGN central engine emission. A mock analysis of the module revealed good recovery of true parameters, with only a slight bias toward higher input values, further validating its reliability. We tested the module on a sample of 50 X-ray-detected local galaxies, including low-ionization nuclear emission-line regions (LINERs) and Seyferts, and demonstrated its capacity to accurately estimate bolometric luminosities, even in the presence of significant galaxy contamination. Notably, the previous X-ray module failed to provide AGN solutions for this sample, stressing the need for a novel approach. Comparisons with mid-luminosity AGN datasets confirm the module’s robustness and applicability up to LX < 1045 erg/s. We also expanded the X-ray-to-bolometric correction formula, making it applicable to AGN spanning ten orders of magnitude in luminosity, and revealing lower kX values for LLAGN than typically assumed. Additionally, our analysis of the αox index, which represents the slope between UV and X-ray emissions, uncovered trends that differ from those observed in high-luminosity AGN. Unlike quasars, where αox correlates with λEdd, LLAGN exhibit nearly constant or weakly correlated αox values, suggesting a shift in accretion physics and photon production mechanisms in low-luminosity regimes. These results underscore the importance of a multiwavelength approach in AGN studies and reveal distinct behaviors in LLAGN compared to quasars. Our findings significantly advance our understanding of LLAGN and offer a comprehensive framework for future research to complete the AGN population census.

中文翻译:


为低亮度活性星系核量身定制的 CIGALE 模块



低光度活动星系核 (LLAGN) 的光谱能量分布 (SED) 带来了独特的挑战,因为这些天体的发射与其宿主星系的辐射相当,并且所涉及的吸积物理学特别复杂。本研究介绍了一种专为应对这些挑战而设计的新型 CIGALE 模块。该模块将经验 LX-L12 μm 关系与物理驱动的吸积模型相结合,例如平流主导的吸积流 (ADAF) 和截断的吸积盘,从而更准确地描述了 LLAGN 中央发动机排放。对该模块的模拟分析显示,真实参数的恢复良好,仅略微偏向更高的输入值,进一步验证了其可靠性。我们在 50 个 X 射线探测到的局部星系样本上测试了该模块,包括低电离核发射线区域 (LINER) 和 Seyferts,并证明了它准确估计辐射热光度的能力,即使在存在严重星系污染的情况下也是如此。值得注意的是,之前的 X 射线模块无法为该样品提供 AGN 解决方案,因此需要一种新的方法。与中等光度 AGN 数据集的比较证实了该模块的稳健性和高达 LX < 1045 erg/s 的适用性。我们还扩展了 X 射线到辐射热校正公式,使其适用于光度跨越 10 个数量级的 AGN,并揭示了 LLAGN 的 kX 值低于通常假设的。此外,我们对代表紫外线和 X 射线发射之间斜率的 αox 指数的分析揭示了与在高亮度 AGN 中观察到的趋势不同的趋势。 与类星体不同,αox 与 λEdd 相关,LLAGN 表现出几乎恒定或弱相关的 αox 值,这表明在低光度范围内吸积物理学和光子产生机制发生了转变。这些结果强调了多波长方法在 AGN 研究中的重要性,并揭示了与类星体相比,LLAGN 的不同行为。我们的发现极大地促进了我们对 LLAGN 的理解,并为未来的研究提供了一个全面的框架,以完成 AGN 人口普查。
更新日期:2024-12-16