Sleeping Giants Arise: Monitoring the Return of Three Changing-look Quasars to Their High States
Changing-look quasars (CLQs) challenge many models of the quasar central engine. Their extreme variability in both the continuum and broad emission-line fluxes on timescales on the order of years is difficult to explain. To investigate the cause of the observed transitions, we present new contempora...
Saved in:
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/adeb73 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849242799435677696 |
|---|---|
| author | Laura Duffy Michael Eracleous John J. Ruan Qian Yang Jessie C. Runnoe |
| author_facet | Laura Duffy Michael Eracleous John J. Ruan Qian Yang Jessie C. Runnoe |
| author_sort | Laura Duffy |
| collection | DOAJ |
| description | Changing-look quasars (CLQs) challenge many models of the quasar central engine. Their extreme variability in both the continuum and broad emission-line fluxes on timescales on the order of years is difficult to explain. To investigate the cause of the observed transitions, we present new contemporaneous optical and X-ray observations of three faded CLQs as they return to a state of high optical luminosity. Two of these three remained in a quiescent state for more than 10 yr before returning to a new high state. We find that before, during, and after transition, the spectral energy distributions of all three follow predictions for quasars based on X-ray binary outbursts, suggesting that the underlying mechanism is likely a changing accretion rate causing changes in the accretion flow structure. In two of the three cases, the transition between the initial high and low state and the transition between the low and new high state took nearly identical amounts of time, on the order of hundreds of days. This transition timescale is a useful constraint on models of the accretion state changes. The behavior of the broad emission-line profiles suggests that the broad-line region structure is changing during the transition. |
| format | Article |
| id | doaj-art-e112045206b94c4dab0fb16c194bf77f |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-e112045206b94c4dab0fb16c194bf77f2025-08-20T03:59:41ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01989110210.3847/1538-4357/adeb73Sleeping Giants Arise: Monitoring the Return of Three Changing-look Quasars to Their High StatesLaura Duffy0https://orcid.org/0000-0003-1752-679XMichael Eracleous1https://orcid.org/0000-0002-3719-940XJohn J. Ruan2https://orcid.org/0000-0001-8665-5523Qian Yang3https://orcid.org/0000-0002-6893-3742Jessie C. Runnoe4https://orcid.org/0000-0001-8557-2822Department of Astronomy and Astrophysics and Institute for Gravitation and the Cosmos, The Pennsylvania State University , 525 Davey Lab, University Park, PA 16803, USADepartment of Astronomy and Astrophysics and Institute for Gravitation and the Cosmos, The Pennsylvania State University , 525 Davey Lab, University Park, PA 16803, USADepartment of Physics and Astronomy, Bishop’s University , 2600 College Street, Sherbrooke, QC J1M 1Z7, CanadaCenter for Astrophysics, Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USADepartment of Physics and Astronomy, Vanderbilt University , Nashville, TN 37235, USAChanging-look quasars (CLQs) challenge many models of the quasar central engine. Their extreme variability in both the continuum and broad emission-line fluxes on timescales on the order of years is difficult to explain. To investigate the cause of the observed transitions, we present new contemporaneous optical and X-ray observations of three faded CLQs as they return to a state of high optical luminosity. Two of these three remained in a quiescent state for more than 10 yr before returning to a new high state. We find that before, during, and after transition, the spectral energy distributions of all three follow predictions for quasars based on X-ray binary outbursts, suggesting that the underlying mechanism is likely a changing accretion rate causing changes in the accretion flow structure. In two of the three cases, the transition between the initial high and low state and the transition between the low and new high state took nearly identical amounts of time, on the order of hundreds of days. This transition timescale is a useful constraint on models of the accretion state changes. The behavior of the broad emission-line profiles suggests that the broad-line region structure is changing during the transition.https://doi.org/10.3847/1538-4357/adeb73Active galactic nucleiQuasarsAccretionSupermassive black holes |
| spellingShingle | Laura Duffy Michael Eracleous John J. Ruan Qian Yang Jessie C. Runnoe Sleeping Giants Arise: Monitoring the Return of Three Changing-look Quasars to Their High States The Astrophysical Journal Active galactic nuclei Quasars Accretion Supermassive black holes |
| title | Sleeping Giants Arise: Monitoring the Return of Three Changing-look Quasars to Their High States |
| title_full | Sleeping Giants Arise: Monitoring the Return of Three Changing-look Quasars to Their High States |
| title_fullStr | Sleeping Giants Arise: Monitoring the Return of Three Changing-look Quasars to Their High States |
| title_full_unstemmed | Sleeping Giants Arise: Monitoring the Return of Three Changing-look Quasars to Their High States |
| title_short | Sleeping Giants Arise: Monitoring the Return of Three Changing-look Quasars to Their High States |
| title_sort | sleeping giants arise monitoring the return of three changing look quasars to their high states |
| topic | Active galactic nuclei Quasars Accretion Supermassive black holes |
| url | https://doi.org/10.3847/1538-4357/adeb73 |
| work_keys_str_mv | AT lauraduffy sleepinggiantsarisemonitoringthereturnofthreechanginglookquasarstotheirhighstates AT michaeleracleous sleepinggiantsarisemonitoringthereturnofthreechanginglookquasarstotheirhighstates AT johnjruan sleepinggiantsarisemonitoringthereturnofthreechanginglookquasarstotheirhighstates AT qianyang sleepinggiantsarisemonitoringthereturnofthreechanginglookquasarstotheirhighstates AT jessiecrunnoe sleepinggiantsarisemonitoringthereturnofthreechanginglookquasarstotheirhighstates |