Wei-Jian Guo, Zhiwei Pan, Małgorzata Siudek, Jessica Nicole Aguilar, Steven Ahlen, Davide Bianchi, David Brooks, Todd Claybaugh, Kyle Dawson, Axel de la Macorra, Peter Doel, Kevin Fanning, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Klaus Honscheid, Robert Kehoe, Theodore Kisner, Andrew Lambert, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, John Moustakas, Andrea Muñoz-Gutiérrez, Adam Myers, Jundan Nie, Nathalie Palanque-Delabrouille, Claire Poppett, Francisco Prada, Mehdi Rezaie, Graziano Rossi, Eusebio Sanchez, Michael Schubnell, Hee-Jong Seo, Joseph Harry Silber, David Sprayberry, Gregory Tarlé, Benjamin Alan Weaver, Zhimin Zhou and Hu Zou
{"title":"The First Identification of Lyα Changing-look Quasars at High Redshift in DESI","authors":"Wei-Jian Guo, Zhiwei Pan, Małgorzata Siudek, Jessica Nicole Aguilar, Steven Ahlen, Davide Bianchi, David Brooks, Todd Claybaugh, Kyle Dawson, Axel de la Macorra, Peter Doel, Kevin Fanning, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Klaus Honscheid, Robert Kehoe, Theodore Kisner, Andrew Lambert, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, John Moustakas, Andrea Muñoz-Gutiérrez, Adam Myers, Jundan Nie, Nathalie Palanque-Delabrouille, Claire Poppett, Francisco Prada, Mehdi Rezaie, Graziano Rossi, Eusebio Sanchez, Michael Schubnell, Hee-Jong Seo, Joseph Harry Silber, David Sprayberry, Gregory Tarlé, Benjamin Alan Weaver, Zhimin Zhou and Hu Zou","doi":"10.3847/2041-8213/adb426","DOIUrl":null,"url":null,"abstract":"We present two cases of Lyα changing-look (CL) quasars (J1306 and J1512) along with two additional candidates (J1511 and J1602), all discovered serendipitously at z > 2 through the Dark Energy Spectroscopic Instrument and the Sloan Digital Sky Survey. It is the first time to capture CL events in Lyα at high redshift, which is crucial for understanding the underlying mechanisms driving the CL phenomenon and the evolution of high-redshift quasars and galaxies. We find that the accretion rate in the dim state for these CL objects corresponds to a relatively low value ( ), which suggests that the inner region of the accretion disk might be in transition between the advection dominated accretion flow ( ) and the canonical accretion disk (optically thick, geometrically thin). However, unlike in C iv CL quasars in which broad Lyα remained, the broad C iv may still persist after a CL event occurs in Lyα, making the physical origin of the CL and ionization mechanism event more puzzling and interesting.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"31 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Astrophysical Journal Letters","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3847/2041-8213/adb426","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
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Abstract
We present two cases of Lyα changing-look (CL) quasars (J1306 and J1512) along with two additional candidates (J1511 and J1602), all discovered serendipitously at z > 2 through the Dark Energy Spectroscopic Instrument and the Sloan Digital Sky Survey. It is the first time to capture CL events in Lyα at high redshift, which is crucial for understanding the underlying mechanisms driving the CL phenomenon and the evolution of high-redshift quasars and galaxies. We find that the accretion rate in the dim state for these CL objects corresponds to a relatively low value ( ), which suggests that the inner region of the accretion disk might be in transition between the advection dominated accretion flow ( ) and the canonical accretion disk (optically thick, geometrically thin). However, unlike in C iv CL quasars in which broad Lyα remained, the broad C iv may still persist after a CL event occurs in Lyα, making the physical origin of the CL and ionization mechanism event more puzzling and interesting.
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