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| 題名: | Slow-blue nuclear hypervariables in PanSTARRS-1 |
| 作者: | 陳婷琬;Lawrence, A.;Bruce, A. G.;MacLeod, C.;Gezari, S.;Elvis, M.;Ward, M.;Smartt, S. J.;Smith, K. W.;Wright, D.;Fraser, M.;Marshall, P.;Kaiser, N.;Burgett, W.;Magnier, E.;Tonry, J.;Chambers, K.;Wainscoat, R.;Waters, C.;Price, P.;Metcalfe, N.;Valenti, S.;Kotak, R.;Mead, A.;Inserra, C.;Chen, T. W.;Soderberg, A. |
| 貢獻者: | 理學院天文研究所 |
| 關鍵詞: | accretion;accretion discs;Amplitudes;ASTRONOMY AND ASTROPHYSICS;Astrophysics;Galaxies;galaxies: active;galaxies: nuclei;gravitational lensing: micro;Luminosity;Object recognition;Photometry;quasars: general;Radio astronomy;Sky surveys (astronomy);Spectroscopic telescopes;Spectrum analysis;Star & galaxy formation;Stars;Supernovae;Telescopes |
| 日期: | 2016-11-21 |
| 上傳時間: | 2026-04-21 14:58:43 (UTC+8) |
| 出版者: | Oxford University Press;London: Oxford University Press |
| 摘要: | 摘要： We discuss 76 large amplitude transients (Δm > 1.5) occurring in the nuclei of galaxies, nearly all with no previously known active galactic nucleus (AGN). They have been discovered as part of the Pan-STARRS1 (PS1) 3π survey, by comparison with Sloan Digital Sky Survey (SDSS) photometry a decade earlier, and then monitored with the Liverpool Telescope, and studied spectroscopically with the William Herschel Telescope (WHT). Based on colours, light-curve shape, and spectra, these transients fall into four groups. A few are misclassified stars or objects of unknown type. Some are red/fast transients and are known or likely nuclear supernovae. A few are either radio sources or erratic variables and so likely blazars. However the majority (∼66 per cent) are blue and evolve slowly, on a time-scale of years. Spectroscopy shows them to be AGN at z ∼ 0.3 − 1.4, which must have brightened since the SDSS photometry by around an order of magnitude. It is likely that these objects were in fact AGN a decade ago, but too weak to be recognized by SDSS; they could then be classed as ‘hypervariable’ AGN. By searching the SDSS Stripe 82 quasar database, we find 15 similar objects. We discuss several possible explanations for these slow-blue hypervariables – (i) unusually luminous tidal disruption events; (ii) extinction events; (iii) changes in accretion state; and (iv) large amplitude microlensing by stars in foreground galaxies. A mixture of explanations (iii) and (iv) seems most likely. Both hold promise of considerable new insight into the AGN phenomenon.
出版者： London: Oxford University Press
出版日期： 2016-11-21
出處： Monthly notices of the Royal Astronomical Society, 2016-11, Vol.463 (1), p.296-331
資源來源： Alma/SFX Local Collection
版權： 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society 2016
版權： Copyright Oxford University Press, UK Nov 21, 2016
識別號： ISSN: 0035-8711
識別號： ISSN: 1365-8711
識別號： ISSN: 1365-2966
識別號： EISSN: 1365-2966
識別號： DOI: 10.1093/mnras/stw1963 |
| 顯示於類別: | [天文研究所] 期刊論文
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