University of Groningen
The life cycle of radio galaxies as seen by LOFAR
Brienza, Marisa
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Publication date:
2018
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Brienza, M. (2018). The life cycle of radio galaxies as seen by LOFAR. Rijksuniversiteit Groningen.
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Propositions
accompanying the dissertation
The life cycle of radio galaxies
as seen by LOFAR
1. Not all remnant radio galaxies have ultra-steep radio spectra at low frequency, contrary to what is commonly assumed. (Chapters 2, 3)
2. Low surface brightness emission in radio galaxies is not always a remnant from a past epoch of jet activity. (Chapters 3 and 4)
3. In the study of radio galaxy evolution, MHz-frequency observations become even more powerful when combined with GHz-frequency observations. (Chapters 2, 3, 4 and 5)
4. At low frequencies, the fraction of remnant radio galaxies with respect to the total radio galaxy population remains low, contrary to earlier expectations. This suggests that the luminosity evolution of the radio plasma is very fast after the jet switches off. (Chapters 2, 6)
5. Monte Carlo simulations demonstrate that the expansion of the plasma of remnant radio galaxies into the surrounding medium plays a crucial role in the luminosity evolution of the remnant (Chapter 3).
6. The paucity of remnants associated with compact radio galaxies suggests that the duty cycle of most radio galaxies must be longer than the remnant phase, i.e. a few tens of Myr. (Chapter 6)
7. With its unprecedented sensitivity and resolution, LOFAR has allowed us to perform the first systematic search for remnant radio galaxies at 150 MHz, and much more will soon be accomplished thanks to the LOFAR Two-metre Sky Survey. 8. Challenges are our opportunity to create new solutions, to think differently and to increase our knowledge.
9. Wise people have more doubts than certainties.
10. Travel is fatal to prejudice, bigotry, and narrow-mindedness. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one’s lifetime. (Mark Twain)
11. Scientists in their laboratories are not only technicians: they are also children placed before natural phenomena which impress them like a fairy tale.
(inspired by Marie Curie)
