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arXiv 1802.02782astro-ph.GA
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红外线中深探测。IV。在$z\sim6$的微弱类星体的低爱丁顿比:不是每个超大质量黑洞都在早期宇宙中快速增长

The Infrared Medium-deep Survey. IV. Low Eddington Ratio of A Faint Quasar at $z\sim6$: Not Every Supermassive Black Hole is Growing Fast in the Early Universe

Yongjung Kim, Myungshin Im, Yiseul Jeon, Minjin Kim, Minhee Hyun, Dohyeong Kim, Jae-Woo Kim, Yoon Chan Taak, Yongmin Yoon, Changsu Choi, Jueun Hong, Hyunsung Da… 展开作者

Yongjung Kim, Myungshin Im, Yiseul Jeon, Minjin Kim, Minhee Hyun, Dohyeong Kim, Jae-Woo Kim, Yoon Chan Taak, Yongmin Yoon, Changsu Choi, Jueun Hong, Hyunsung David Jun, Marios Karouzos, Duho Kim, Ji Hoon Kim, Seong-Kook Lee, Soojong Pak, Won-Kee Park

摘要:

到目前为止,大多数在$z\sim6$发现的发光类星体都是以爱丁顿比($λ_{\rm{Edd}}\sim1$)处于最大吸积状态,这表明早期宇宙的核活动增强。然而,这可能不是超大质量黑洞(SMBH)生长的全貌,因为以前的研究还没有涉及到更有可能拥有低$λ_{\rm{Edd}}$的SMBH的微弱类星体。为了更好地了解早期宇宙中类星体的吸积活动,我们获得了一个类星体IMS J220417.92+011144.8(以下简称IMS J2204+0112)的深近红外光谱,它是$z\sim6$发现的最暗类星体之一。从近红外光谱中的红移C IV $λ1549$发射线,我们发现IMS J2204+0112拥有一个大约10亿太阳质量的SMBH和$λ_{\rm{Edd}} \sim 0.1$,但这两个量都有很大的不确定性(0.41 dex)。IMS J2204+0112在$z\sim6$的类星体中具有最低的爱丁顿比,但在$z\sim2$的类星体中具有共同的值。它的低$λ_{\rm{Edd}}$可以用两种情况来解释; SMBH从恒星质量黑洞通过短持续时间的超爱丁顿吸积事件或从大质量黑洞种子($\sim10^{5}\,M_{\odot}$)与爱丁顿有限吸积的增长。更微弱的类星体的近红外光谱需要更好地了解在$z \sim 6$的SMBH吸积活动。

英文摘要:

To date, most of the luminous quasars known at $z\sim6$ have been found to be in maximal accretion with the Eddington ratios, $λ_{\rm{Edd}}\sim1$, suggesting enhanced nuclear activities in the early universe. However, this may not be the whole picture of supermassive black hole (SMBH) growth since previous studies have not reached on faint quasars that are more likely to harbor SMBHs with low $λ_{\rm{Edd}}$. To gain a better understanding on the accretion activities in quasars in the early universe, we obtained a deep near-infrared (NIR) spectrum of a quasar, IMS J220417.92+011144.8 (hereafter IMS J2204+0112), one of the faintest quasars that have been identified at $z\sim6$. From the redshifted C IV $λ1549$ emission line in the NIR spectrum, we find that IMS J2204+0112 harbors a SMBH with about a billion solar mass and $λ_{\rm{Edd}} \sim 0.1$, but with a large uncertainty in both quantities (0.41 dex). IMS J2204+0112 has one of the lowest Eddington ratios among quasars at $z\sim6$, but a common value among quasars at $z\sim2$. Its low $λ_{\rm{Edd}}$ can be explained with two scenarios; the SMBH growth from a stellar mass black hole through short-duration super-Eddington accretion events or from a massive black hole seed ($\sim10^{5}\,M_{\odot}$) with Eddington-limited accretion. NIR spectra of more faint quasars are needed to better understand the accretion activities of SMBHs at $z \sim 6$.

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