The first high-redshift changing-look quasars
| Autor: | Barry McKernan, Nicholas P. Ross, K. E. Saavik Ford, Daniel Stern, Matthew J. Graham, Giorgio Calderone |
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| Rok vydání: | 2020 |
| Předmět: |
Astrophysics::High Energy Astrophysical Phenomena
Population FOS: Physical sciences Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics 01 natural sciences Virial theorem symbols.namesake 0103 physical sciences Emission spectrum education Spectroscopy 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Physics education.field_of_study 010308 nuclear & particles physics Astronomy and Astrophysics Quasar Light curve Astrophysics - Astrophysics of Galaxies Redshift Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Eddington luminosity symbols |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 498:2339-2353 |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1093/mnras/staa2415 |
| Popis: | We report on three redshift $z>2$ quasars with dramatic changes in their C IV emission lines, the first sample of changing-look quasars (CLQs) at high redshift. This is also the first time the changing-look behaviour has been seen in a high-ionisation emission line. SDSS J1205+3422, J1638+2827, and J2228+2201 show interesting behaviour in their observed optical light curves, and subsequent spectroscopy shows significant changes in the C IV broad emission line, with both line collapse and emergence being displayed on rest-frame timescales of $\sim$240-1640 days. These are rapid changes, especially when considering virial black hole mass estimates of $M_{\rm BH} > 10^{9} M_{\odot}$ for all three quasars. Continuum and emission line measurements from the three quasars show changes in the continuum-equivalent width plane with the CLQs seen to be on the edge of the full population distribution, and showing indications of an intrinsic Baldwin effect. We put these observations in context with recent state-change models, and note that even in their observed low-state, the C IV CLQs are generally above $\sim$5\% in Eddington luminosity. 12 pages, 7 figures, 4 tables. All data, analysis code and text are fully available at: github.com/d80b2t/CIV_CLQs. Comments, questions and suggestions welcome and encouraged |
| Databáze: | OpenAIRE |
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