Extreme Variability Quasars in Their Various States. II: Spectral Variation Revealed with Multi-epoch Spectra
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| Format: | Preprint |
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2023
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| author | Ren, Wenke Wang, Junxian Cai, Zhenyi Hu, Xufan |
| author_facet | Ren, Wenke Wang, Junxian Cai, Zhenyi Hu, Xufan |
| contents | We previously built a sample of 14,012 extremely variable quasars (EVQs) based on SDSS and Pan-STARRS1 photometric observations. In this work we present the spectral fitting to their SDSS spectra, and study the spectral variation in 1,259 EVQs with multi-epoch SDSS spectra (after prudently excluding spectra with potentially unreliable spectroscopic photometry). We find clear "bluer-when-brighter" trend in EVQs, consistent with previous findings of normal quasars and AGNs. We detect significant intrinsic Baldwin effect (iBeff, i.e., smaller line EW at higher continuum flux in individual AGNs) in the broad MgII and CIV lines of EVQs. Meanwhile, no systematical iBeff is found for the broad Hb line, which could be attributed to strong host contamination at longer wavelengths. Remarkably, by comparing the iBeff slope of EVQs with archived changing-look quasars (CLQs), we show that the CLQs identified in literature are mostly likely a biased (due to its definition) sub-population of EVQs, rather than a distinct population of quasars. We also found no significant broad line breathing of either Hb, MgII or CIV, suggesting the broad line breathing in quasars may disappear at longer timescales ($\sim$ 3000 days). |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2312_10869 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Extreme Variability Quasars in Their Various States. II: Spectral Variation Revealed with Multi-epoch Spectra Ren, Wenke Wang, Junxian Cai, Zhenyi Hu, Xufan Astrophysics of Galaxies We previously built a sample of 14,012 extremely variable quasars (EVQs) based on SDSS and Pan-STARRS1 photometric observations. In this work we present the spectral fitting to their SDSS spectra, and study the spectral variation in 1,259 EVQs with multi-epoch SDSS spectra (after prudently excluding spectra with potentially unreliable spectroscopic photometry). We find clear "bluer-when-brighter" trend in EVQs, consistent with previous findings of normal quasars and AGNs. We detect significant intrinsic Baldwin effect (iBeff, i.e., smaller line EW at higher continuum flux in individual AGNs) in the broad MgII and CIV lines of EVQs. Meanwhile, no systematical iBeff is found for the broad Hb line, which could be attributed to strong host contamination at longer wavelengths. Remarkably, by comparing the iBeff slope of EVQs with archived changing-look quasars (CLQs), we show that the CLQs identified in literature are mostly likely a biased (due to its definition) sub-population of EVQs, rather than a distinct population of quasars. We also found no significant broad line breathing of either Hb, MgII or CIV, suggesting the broad line breathing in quasars may disappear at longer timescales ($\sim$ 3000 days). |
| title | Extreme Variability Quasars in Their Various States. II: Spectral Variation Revealed with Multi-epoch Spectra |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2312.10869 |