Probing the disk–corona systems and broad-line regions of changing-look quasars with X-ray and optical observations

Xiangyu Jin; John J. Ruan; Daryl Haggard; Marie Joëlle Gingras; Joseph Hountalas; Chelsea L. MacLeod; Scott F. Anderson; Anh Doan; Michael Eracleous; Paul J. Green; Jessie C. Runnoe

doi:10.3847/1538-4357/abeb17

Probing the disk–corona systems and broad-line regions of changing-look quasars with X-ray and optical observations

Xiangyu Jin, John J. Ruan, Daryl Haggard, Marie Joëlle Gingras, Joseph Hountalas, Chelsea L. MacLeod, Scott F. Anderson, Anh Doan, Michael Eracleous, Paul J. Green, Jessie C. Runnoe

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Abstract

“Changing-look” quasars are a new class of highly variable active galactic nuclei that have changed their spectral type over surprisingly short timescales of just a few years. The origin of this phenomenon is debated, but is likely to reflect some change in the accretion flow. To investigate the disk–corona systems in these objects, we measure optical/UV–X-ray spectral indices (a_OX) and Eddington ratios (l_Edd) of 10 previously discovered changing-look quasars at two or more epochs. By comparing these data with simulated results based on the behavior of X-ray binaries, we find possible similarities in spectral indices below the 1% Eddington ratio. We further investigate the Eddington ratios of changing-look quasars before and after their spectral type changes, and find that changing-look quasars cross the 1% Eddington ratio boundary when their broad emission lines disappear/emerge. This is consistent with the disk-wind model as the origin of broad emission lines.

Original language	English (US)
Article number	20
Journal	Astrophysical Journal
Volume	912
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/abeb17
State	Published - May 1 2021

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/1538-4357/abeb17

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@article{dffa558ffe384c04b096703de185b3db,

title = "Probing the disk–corona systems and broad-line regions of changing-look quasars with X-ray and optical observations",

abstract = "“Changing-look” quasars are a new class of highly variable active galactic nuclei that have changed their spectral type over surprisingly short timescales of just a few years. The origin of this phenomenon is debated, but is likely to reflect some change in the accretion flow. To investigate the disk–corona systems in these objects, we measure optical/UV–X-ray spectral indices (aOX) and Eddington ratios (lEdd) of 10 previously discovered changing-look quasars at two or more epochs. By comparing these data with simulated results based on the behavior of X-ray binaries, we find possible similarities in spectral indices below the 1% Eddington ratio. We further investigate the Eddington ratios of changing-look quasars before and after their spectral type changes, and find that changing-look quasars cross the 1% Eddington ratio boundary when their broad emission lines disappear/emerge. This is consistent with the disk-wind model as the origin of broad emission lines.",

author = "Xiangyu Jin and Ruan, {John J.} and Daryl Haggard and Gingras, {Marie Jo{\"e}lle} and Joseph Hountalas and MacLeod, {Chelsea L.} and Anderson, {Scott F.} and Anh Doan and Michael Eracleous and Green, {Paul J.} and Runnoe, {Jessie C.}",

note = "Funding Information: Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. The SDSS-IV acknowledges support and resources from the center for High-Performance Computing at the University of Utah. The SDSS website is www.sdss.org. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. Publisher Copyright: {\textcopyright} 2021. The American Astronomical Society. All rights reserved.",

year = "2021",

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doi = "10.3847/1538-4357/abeb17",

language = "English (US)",

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T1 - Probing the disk–corona systems and broad-line regions of changing-look quasars with X-ray and optical observations

AU - Jin, Xiangyu

AU - Ruan, John J.

AU - Haggard, Daryl

AU - Gingras, Marie Joëlle

AU - Hountalas, Joseph

AU - MacLeod, Chelsea L.

AU - Anderson, Scott F.

AU - Doan, Anh

AU - Eracleous, Michael

AU - Green, Paul J.

AU - Runnoe, Jessie C.

N1 - Funding Information: Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. The SDSS-IV acknowledges support and resources from the center for High-Performance Computing at the University of Utah. The SDSS website is www.sdss.org. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. Publisher Copyright: © 2021. The American Astronomical Society. All rights reserved.

PY - 2021/5/1

Y1 - 2021/5/1

N2 - “Changing-look” quasars are a new class of highly variable active galactic nuclei that have changed their spectral type over surprisingly short timescales of just a few years. The origin of this phenomenon is debated, but is likely to reflect some change in the accretion flow. To investigate the disk–corona systems in these objects, we measure optical/UV–X-ray spectral indices (aOX) and Eddington ratios (lEdd) of 10 previously discovered changing-look quasars at two or more epochs. By comparing these data with simulated results based on the behavior of X-ray binaries, we find possible similarities in spectral indices below the 1% Eddington ratio. We further investigate the Eddington ratios of changing-look quasars before and after their spectral type changes, and find that changing-look quasars cross the 1% Eddington ratio boundary when their broad emission lines disappear/emerge. This is consistent with the disk-wind model as the origin of broad emission lines.

AB - “Changing-look” quasars are a new class of highly variable active galactic nuclei that have changed their spectral type over surprisingly short timescales of just a few years. The origin of this phenomenon is debated, but is likely to reflect some change in the accretion flow. To investigate the disk–corona systems in these objects, we measure optical/UV–X-ray spectral indices (aOX) and Eddington ratios (lEdd) of 10 previously discovered changing-look quasars at two or more epochs. By comparing these data with simulated results based on the behavior of X-ray binaries, we find possible similarities in spectral indices below the 1% Eddington ratio. We further investigate the Eddington ratios of changing-look quasars before and after their spectral type changes, and find that changing-look quasars cross the 1% Eddington ratio boundary when their broad emission lines disappear/emerge. This is consistent with the disk-wind model as the origin of broad emission lines.

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Probing the disk–corona systems and broad-line regions of changing-look quasars with X-ray and optical observations

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