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A Radio View of the Bullet Cluster from 100 MHz to 9 GHz

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dc.contributor.advisor Johnston-Hollitt, Melanie
dc.contributor.author Srinivasan, Raghav
dc.date.accessioned 2015-10-29T02:57:49Z
dc.date.accessioned 2022-11-03T03:29:51Z
dc.date.available 2015-10-29T02:57:49Z
dc.date.available 2022-11-03T03:29:51Z
dc.date.copyright 2015
dc.date.issued 2015
dc.identifier.uri https://ir.wgtn.ac.nz/handle/123456789/29764
dc.description.abstract We investigate a sample of 10 massive galaxy clusters for diffuse synchrotron emission. The shortlisted clusters are drawn from a sample of clusters observed with the South Pole Telescope (SPT) shown to have high Sunyaev-Zeldovich (SZ) signals.They are analysed for diffuse emission from the results of the Australia Telescope Compact Array (ATCA) archival data reduction. The focus then is on the cluster with the most prominent diffuse emission - the Bullet cluster. We used the Murchison Widefield Array Commissioning Survey (MWACS) data in conjunction with the ATCA images to derive the spectral behaviour of the Bullet cluster from 0.118 GHz to 8.896 GHz. In particular, we study the spectral properties of the known radio halo and radio relic. We search for spectral bending of this diffuse emission as seen in other clusters like the Coma cluster, A2256, A521 and A3256. We detect the radio relic at all frequencies in the cluster periphery. Polarised flux is detected for the relic at all frequencies except at 1.344 GHz and as expected the percentage polarisation increases with frequency. Our spectral index values of -1.08 ± 0.02 and -1.74 ± 0.22 for 2 regions of the radio relic agreed with the literature. We detect spectral flattening for a region in the radio relic at 4.532 GHz. This is a common spectral characteristic for a radio galaxy. This suggests that the source could be a recently dead radio galaxy. We discuss a scenario in which a dead radio galaxy supplying seed electrons for reacceleration and a merger process providing the required energy for the diffuse radio relic. We detect the radio halo at all frequencies and we derive a spectral index of -2.11±0.03 using our ATCA flux measurements. Our individual flux measurements at 1.344 and 2.1 GHz agree with the literature. However, we get a steeper ATCA spectral index value for the radio halo as compared to the existing value in the literature. We observe spectral flattening of the radio halo in the Bullet cluster at low frequencies between 0.180 GHz and 1.3 GHz. This is similar to the spectral property of the halo in clusters like the Coma cluster, A521 and A3256. en_NZ
dc.language en_NZ
dc.language.iso en_NZ
dc.publisher Te Herenga Waka—Victoria University of Wellington en_NZ
dc.rights Access is restricted to staff and students only until 11/2017. For information please contact the Library. en_NZ
dc.subject Radio halo en_NZ
dc.subject Bullet cluster en_NZ
dc.subject Diffuse emission en_NZ
dc.title A Radio View of the Bullet Cluster from 100 MHz to 9 GHz en_NZ
dc.type Text en_NZ
vuwschema.contributor.unit School of Chemical and Physical Sciences en_NZ
vuwschema.subject.anzsrcfor 020103 Cosmology and Extragalactic Astronomy en_NZ
vuwschema.subject.anzsrcfor 020104 Galactic Astronomy en_NZ
vuwschema.subject.anzsrcseo 970102 Expanding Knowledge in the Physical Sciences en_NZ
vuwschema.type.vuw Awarded Research Masters Thesis en_NZ
thesis.degree.discipline Physics en_NZ
thesis.degree.grantor Te Herenga Waka—Victoria University of Wellington en_NZ
thesis.degree.level Masters en_NZ
thesis.degree.name Master of Science en_NZ

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