红移7.19类星体中的潮汐瓦解事件
A tidal disruption event in a quasar at redshift 7.19
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中文总结 AI 辅助
报道GNz7q（红移7.19）中一个长寿命核瞬变，经多波段观测和t^-5/3模型拟合，确认为高能潮汐瓦解事件，揭示了早期宇宙黑洞的间歇性吸积。
中文摘要 AI 辅助
我们报道了GNz7q中一个长寿命的核瞬变事件，GNz7q是一个红移z=7.19的红类星体，由一个约3×10^7太阳质量的黑洞提供能量，并由一个致密的、布满尘埃的星暴星系所承载。该瞬变事件在HST、Spitzer和JWST超过二十年的成像中被识别出来。在快速上升之后，源在静止系紫外波段约2个静止系年内平滑地变暗了约Δm≃1.1星等，在1–5微米范围内具有连贯的、随波长变化的演化，这使得GNz7q位于SDSS类星体变率分布的第99.9百分位以上，并且在z≳5处不存在这种演化。其持续时间和能量学不支持超亮超新星，而随机类星体变率重现多波段演化的概率≲10^-5。一个结合热连续谱与t^-5/3衰减的全波段模型重现了光变曲线，得到的峰值热光度约为3×10^45 erg s^-1，辐射能量约为1.5×10^53 erg，这意味着一个几倍太阳质量恒星的潮汐瓦解，并使该事件跻身已知最具能量的潮汐瓦解事件（TDE）之列。独立的JWST/NIRSpec光谱中一个红移的、极宽的巴耳末线分量与一个瞬变的、非维里化的宽线区一致。JWST/MIRI测光进一步揭示了来自亚秒差距半径处约1500 K尘埃的延迟中红外发射，与耀发的尘埃回波一致。GNz7q相对较低的黑洞质量和致密的恒星形成核是TDE预期最有效的条件。这些观测提供了大爆炸后7亿年时黑洞间歇性吸积及其尘埃核环境的时域视角。Roman和Euclid在近红外的宽视场巡天，辅以LSST在较低红移处的观测，可能会大量发现此类瞬变事件。
英文摘要
We report a long-lived nuclear transient in GNz7q, a red quasar at $z=7.19$ powered by a $\sim3\times10^{7}\,M_\odot$ black hole and hosted by a compact, dusty starburst galaxy. The transient was identified in more than two decades of imaging with HST, Spitzer, and JWST. After a rapid rise, the source faded smoothly by $Δm\simeq1.1$ mag in the rest-frame ultraviolet over $\sim2$ rest-frame yr, with coherent, wavelength-dependent evolution across 1--5 $μ$m that places GNz7q above the 99.9th percentile of the SDSS quasar variability distribution and is absent at $z\gtrsim5$. The duration and energetics disfavor superluminous supernovae, and stochastic quasar variability reproduces the multi-band evolution with a probability of $\lesssim10^{-5}$. A panchromatic model combining a thermal continuum with a $t^{-5/3}$ decline reproduces the light curves, yielding a peak bolometric luminosity of $\simeq3\times10^{45}$ erg s$^{-1}$ and a radiated energy of $\simeq1.5\times10^{53}$ erg, which imply the tidal disruption of a star of a few solar masses and place the event among the most energetic tidal disruption events (TDEs) known. A redshifted, extremely broad Balmer-line component in independent JWST/NIRSpec spectroscopy is consistent with a transient, non-virialized broad-line region. JWST/MIRI photometry further reveals delayed mid-infrared emission from $\simeq1500$ K dust at a sub-parsec radius, consistent with a dust echo of the flare. The relatively low black-hole mass and dense star-forming nucleus of GNz7q are conditions under which TDEs are expected to be most efficient. These observations provide a time-domain view of episodic black-hole fueling and its dusty nuclear environment 700 million years after the Big Bang. Wide-field surveys with Roman and Euclid in the near-infrared, complemented by LSST at lower redshifts, may uncover such transients in large numbers.
发表机构
- University of Toronto（多伦多大学）
- Dunlap Institute for Astronomy and Astrophysics, University of Toronto（多伦多大学邓普天文学与天体物理研究所）
- Cosmic Dawn Center (DAWN)（宇宙黎明中心）
- Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）
- Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）
- Department of Astronomy, School of Physics, Peking University（北京大学物理学院天文学系）
- The University of Texas at Austin（德克萨斯大学奥斯汀分校）
- Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理学研究所）
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