文章基本信息

标题：Near- to mid-infrared spectroscopy of the heavily obscured AGN LEDA 1712304 with AKARI/IRC
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作者：T. Tsuchikawa ; H. Kaneda ; S. Oyabu 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：626
DOI：10.1051/0004-6361/201935483
语种：English
出版社：EDP Sciences
摘要：Context. Although heavily obscured active galactic nuclei (AGNs) have been found by many observational studies, the properties of the surrounding dust are poorly understood. Using AKARI/IRC spectroscopy, we discovered a new heavily obscured AGN in LEDA 1712304 which shows a deep spectral absorption feature due to silicate dust.Aims.We study the infrared (IR) spectral properties of circumnuclear silicate dust in LEDA 1712304.Methods.We performed IR spectral fitting, considering silicate dust properties such as composition, porosity, size, and crystallinity. Spectral energy distribution fitting was also performed on the flux densities in the UV to submillimeter range to investigate the global spectral properties.Results.The best-fit model indicates 0.1 μm-sized porous amorphous olivine (Mg2xFe2−2xSiO4;x = 0.4) with 4% crystalline pyroxene. The optical depth isτsil ∼ 2.3, while the total IR luminosity and stellar mass are estimated to beLIR = (5 ± 1)×1010 L⊙andMstar = (2.7 ± 0.8)×109 M⊙, respectively. In such lowLIRandMstarranges, there are few galaxies that show such a largeτsil.Conclusion.The silicate dust in the AGN torus of LEDA 1712304 has properties that are notably similar to those in other AGNs overall, but slightly different in the wing shape of the absorption profile. The porosity of the silicate dust suggests dust coagulation or processing in the circumnuclear environments, while the crystallinity suggests that the silicate dust is relatively fresh.
关键词：eninfrared: galaxiesgalaxies: nucleigalaxies: individual: LEDA 1712304