Galaxy-cluster interactions : bent jets, wakes, and Ram pressure stripping
Galaxy-cluster interactions : bent jets, wakes, and Ram pressure stripping
The work in this thesis is concerned with the physical processes that take place in clusters of galaxies, and in particular the manifestations of the galaxy-intracluster medium (ICM) interactions.
The effects of such interactions are seen in wide-angle tailed radio galaxies (WATs), which are radio galaxies whose jets are bent in a wide C-shape. Their appearance can be attributed to the combined action of ram pressure and buoyancy forces. A new method is developed for measuring the galaxy velocity independently from the jet velocity, by solving the detailed hydrodynamical equations for a specific point on the radio jets. The technique is applied to two radio galaxies 4C 34.16 and 3C 354. The jet velocity is also calculated: for both sources it is found to be in the range of (103 - 104) km s-1.
The first quantitative attempt is made to explain the sudden flaring and subsequent deceleration of radio jets from relativistic to subrelativistic velocities. According to theoretical models such jet structures could arise when the jets cross the interface between the hot, X-ray emitting interstellar medium (ISM) of the host galaxy and the ICM of any surrounding cluster. Using ROSAT PSPC and HRI data, the underlying, extended X-ray emission is detected from the galaxy which hosts 3C 354. It is shown in order to reach firm conclusions for the position and strength of the ISM/ICM interface in this system X-ray data of higher spectral resolution are required.
A sample of WAT sources is compiled in order to investigate the dynamics of their host clusters. The direction in which their jets are bent is used to discover their orbits in the clusters. X-ray observation retrieved from the ROSAT archive are used to determine their properties (accurate position of the cluster centre, size and morphology). WATs are found to lie preferentially on radial orbits heading away from or towards the cluster centre. The results are consistent with the idea that WATs are radio galaxies that originated in poor groups, but are now in the process of falling into richer clusters.
Another result of galaxy-ICM interactions is the creation of X-ray wakes, down-stream from each moving galaxy. This phenomenon is detected in the ICM around the WAT source 4C 34.16. Its properties revealed by X-ray observations (density and temperature) are used to measure the projection of the galaxy velocity on the plane of the sky.
University of Southampton
Sakelliou, Irini
f86be6d8-0465-49ca-ac73-81f2c2c8d028
1998
Sakelliou, Irini
f86be6d8-0465-49ca-ac73-81f2c2c8d028
Sakelliou, Irini
(1998)
Galaxy-cluster interactions : bent jets, wakes, and Ram pressure stripping.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The work in this thesis is concerned with the physical processes that take place in clusters of galaxies, and in particular the manifestations of the galaxy-intracluster medium (ICM) interactions.
The effects of such interactions are seen in wide-angle tailed radio galaxies (WATs), which are radio galaxies whose jets are bent in a wide C-shape. Their appearance can be attributed to the combined action of ram pressure and buoyancy forces. A new method is developed for measuring the galaxy velocity independently from the jet velocity, by solving the detailed hydrodynamical equations for a specific point on the radio jets. The technique is applied to two radio galaxies 4C 34.16 and 3C 354. The jet velocity is also calculated: for both sources it is found to be in the range of (103 - 104) km s-1.
The first quantitative attempt is made to explain the sudden flaring and subsequent deceleration of radio jets from relativistic to subrelativistic velocities. According to theoretical models such jet structures could arise when the jets cross the interface between the hot, X-ray emitting interstellar medium (ISM) of the host galaxy and the ICM of any surrounding cluster. Using ROSAT PSPC and HRI data, the underlying, extended X-ray emission is detected from the galaxy which hosts 3C 354. It is shown in order to reach firm conclusions for the position and strength of the ISM/ICM interface in this system X-ray data of higher spectral resolution are required.
A sample of WAT sources is compiled in order to investigate the dynamics of their host clusters. The direction in which their jets are bent is used to discover their orbits in the clusters. X-ray observation retrieved from the ROSAT archive are used to determine their properties (accurate position of the cluster centre, size and morphology). WATs are found to lie preferentially on radial orbits heading away from or towards the cluster centre. The results are consistent with the idea that WATs are radio galaxies that originated in poor groups, but are now in the process of falling into richer clusters.
Another result of galaxy-ICM interactions is the creation of X-ray wakes, down-stream from each moving galaxy. This phenomenon is detected in the ICM around the WAT source 4C 34.16. Its properties revealed by X-ray observations (density and temperature) are used to measure the projection of the galaxy velocity on the plane of the sky.
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Published date: 1998
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Local EPrints ID: 463561
URI: http://eprints.soton.ac.uk/id/eprint/463561
PURE UUID: be3151cf-a930-43e6-be44-04fa0404f624
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Date deposited: 04 Jul 2022 20:53
Last modified: 16 Mar 2024 19:05
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Author:
Irini Sakelliou
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