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Author
Date
2019Type
- Doctoral Thesis
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Abstract
Variable emission is a ubiquitous property of active galactic nuclei (AGN). It can be observed or inferred at essentially all timescales, from hours to billions of years, and across the entire electromagnetic spectrum. Since most of the AGN luminosity originates from the accretion of matter into the central supermassive black hole (SMBH), the study of AGN variability can provide crucial information about the physics and structure of the central engine, including at spatial scales that are beyond the resolving power of most of the observing facilities for the majority of the AGN. In addition, the study of AGN variability allows us to probe the close link between SMBHs and their host galaxies by taking into account the fact that the energy injection from the AGN varies with time. In this thesis, I investigate AGN variability on multiple timescales and its effect on the host galaxy by combining multiwavelength observations, phenomenological models, and simulations. With multiwavelength observations, we can investigate AGN variability on an object-by-object basis, phenomenological models describe the general behaviour of the AGN population, while simulations of the AGN luminosity evolution with time (AGN light curves) are very valuable both for the planning of future time-domain surveys and for the interpretation of the observations.
The methods and results presented in this thesis provide a first important step towards a novel unified approach to AGN variability. This approach will be extremely valuable in the upcoming era of time-domain astronomy, in particular by linking phenomena observed in different galaxies and at very different timescales, that may appear unrelated. Show more
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https://doi.org/10.3929/ethz-b-000382815Publication status
publishedExternal links
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Publisher
ETH ZurichSubject
Astronomy and astrophysicsOrganisational unit
03928 - Refregier, Alexandre / Refregier, Alexandre
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