AGN relics in the radio sky: a LOFAR look into spectral ageing and AGN duty cycles

Research output: ThesisThesis fully internal (DIV)

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Abstract

Galaxies have black holes in their nuclei: big galaxies host bigger while small galaxies host smaller black holes. These black holes grow during the lifetime of a galaxy (billions of years) through accretion of matter and they can end up being as massive as billions of suns put together. The accretion is not a steady process but occurs in episodes, each lasting tens of millions of years.
Certain types of galaxies produce strong radio waves during the accretion episodes. The radio emission can be detected for millions of years after the matter accretion episode of a black hole has ended, and it slowly fades as time passes. The observed structures, connected to galaxies which host previously active black holes are known as radio relics.
This thesis investigates radio relics by imaging their radio emission using the revolutionary Dutch built LOw Frequency ARray (LOFAR) radio telescope. We have used LOFAR to study several examples of radio relics and have derived the duration of the black hole accretion episodes as well as the time elapsed since the accretion has stopped. We have also made new relic discoveries, showcasing the promise which LOFAR holds for
future work in this field of research.
Translated title of the contributionRestanten van kosmische radiostralers: een eerste blik met LOFAR
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Groningen
Supervisors/Advisors
  • Morganti, Raffaella, Supervisor
  • Barthel, Pieter, Co-supervisor
Award date6-Feb-2015
Place of Publication[S.l.]
Publisher
Print ISBNs978-90-367-7632-5
Electronic ISBNs978-90-367-7631-8
Publication statusPublished - 2015

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