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The epoch and environmental dependence of radio-loud active galaxy feedback

The epoch and environmental dependence of radio-loud active galaxy feedback
The epoch and environmental dependence of radio-loud active galaxy feedback
This thesis contains the first systematic X-ray investigation of the relationships between the properties of different types of radio-loud AGN and their large-scale environments, using samples at two distinct redshifts to isolate the effects of evolution. I used X-ray observations of the galaxy clusters hosting the radio galaxies to characterise the properties of the environments and compared them with the low-frequency radio properties of the AGN. I found a strong relationship between radio luminosity and ICM richness for lowexcitation radio galaxies (LERGs) but not for high-excitation radio galaxies (HERGs), and tentative evidence of evolution of the environment for HERGs, but not for LERGs.

I then used the X-ray emission from the lobes of the FRII galaxies in the samples to calculate their internal pressures, finding them to be at slightly higher pressures than predicted by equipartition and near pressure balance with their external environment at the lobe mid-points. I made the first estimates of lower limits for lobe-tip Mach numbers for a large sample of lobes; suggesting that about half the lobe tips were driving strong shocks.

Finally I verified that the correlation between LERG radio luminosity and cluster X-ray luminosity is not caused by a common correlation with black hole mass, and also found no evidence that HERG properties are affected by ICM richness, adding evidence for theories of local fuelling for HERGs. I found evidence that HERGs should have a strong relationship between jet power and radio luminosity, but that LERG jet power must be subject to factors additional to black hole mass. I also found evidence that the same mass black hole is associated with lower radio luminosities in FRI morphology galaxies than in FRIIs, perhaps as a result of the higher proton content of FRI jets leading to lower radiative efficiency.
Ineson, Judith
2786e312-601a-4387-bb3d-deda0a05219f
Ineson, Judith
2786e312-601a-4387-bb3d-deda0a05219f
Croston, Judith
b10aa3fb-620e-4ec2-93e5-8594748d4822

Ineson, Judith (2016) The epoch and environmental dependence of radio-loud active galaxy feedback. University of Southampton, Faculty of Physical Sciences and Engineering, Doctoral Thesis, 237pp.

Record type: Thesis (Doctoral)

Abstract

This thesis contains the first systematic X-ray investigation of the relationships between the properties of different types of radio-loud AGN and their large-scale environments, using samples at two distinct redshifts to isolate the effects of evolution. I used X-ray observations of the galaxy clusters hosting the radio galaxies to characterise the properties of the environments and compared them with the low-frequency radio properties of the AGN. I found a strong relationship between radio luminosity and ICM richness for lowexcitation radio galaxies (LERGs) but not for high-excitation radio galaxies (HERGs), and tentative evidence of evolution of the environment for HERGs, but not for LERGs.

I then used the X-ray emission from the lobes of the FRII galaxies in the samples to calculate their internal pressures, finding them to be at slightly higher pressures than predicted by equipartition and near pressure balance with their external environment at the lobe mid-points. I made the first estimates of lower limits for lobe-tip Mach numbers for a large sample of lobes; suggesting that about half the lobe tips were driving strong shocks.

Finally I verified that the correlation between LERG radio luminosity and cluster X-ray luminosity is not caused by a common correlation with black hole mass, and also found no evidence that HERG properties are affected by ICM richness, adding evidence for theories of local fuelling for HERGs. I found evidence that HERGs should have a strong relationship between jet power and radio luminosity, but that LERG jet power must be subject to factors additional to black hole mass. I also found evidence that the same mass black hole is associated with lower radio luminosities in FRI morphology galaxies than in FRIIs, perhaps as a result of the higher proton content of FRI jets leading to lower radiative efficiency.

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Published date: June 2016
Organisations: University of Southampton, Astronomy Group

Identifiers

Local EPrints ID: 400891
URI: http://eprints.soton.ac.uk/id/eprint/400891
PURE UUID: 14d9abf7-6f0a-45e7-ae62-706fdda7173b

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Date deposited: 12 Dec 2016 13:47
Last modified: 17 Jul 2017 18:08

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