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arXiv · 2408.16183

Galaxies Lighting Up: Discovery of Seventy New Turn-on Changing-look Quasars

Qian Yang·Paul J. Green·Xue-Bing Wu·Michael Eracleous·Linhua Jiang·Yuming Fu
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Abstract

"Changing-look quasars" (CLQs), discovered less than a decade ago, show dramatic, rapid changes in optical/UV continuum and broad line emission. The majority of CLQs have been found dimming as "turn-off" CLQs because most selection methods start from samples of spectroscopically-confirmed quasars. We present here a sample of 82 spectroscopically confirmed "turn-on" CLQs, 70 of which are newly identified. The turn-on CLQs are selected from spectroscopically classified galaxies with subsequent significant and dramatic variability in both the optical and mid-infrared bands, indicating a mechanism of changing accretion rate of the supermassive black holes rather than variable obscuration. Based on their bright state Eddington ratios, turn-on CLQs are associated with lower accretion rates compared to turn-off CLQs or typical SDSS quasars with similar redshift and magnitude distributions, even though turn-on CLQs have lower black hole masses. Most turn-on CLQs reside in host galaxies that follow local relations between the central black hole mass and host galaxy properties, such as stellar mass and velocity dispersion. However, their host galaxies have higher mass than normal inactive galaxies, with star formation rates more similar to hosts of Type 2 AGN than to the overall galaxy population.

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Qian Yang, Paul J. Green, Xue-Bing Wu, Michael Eracleous, Linhua Jiang, Yuming Fu. 2024-08-29. Galaxies Lighting Up: Discovery of Seventy New Turn-on Changing-look Quasars. https://arxiv.org/abs/2408.16183

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