| Authors : | Avishek Basu, Patrick Weltevrede, Mike J. Keith, Simon Johnston, Aris Karastergiou, Lucy S. Oswald, Bettina Posselt, Xiaoxi Song and Andrew D. Cameron |
| Authors Affiliation: | 1. Avishek Basu, Patrick Weltevrede, Mike J. Keith (Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, UK, M13 9PL)
2. Simon Johnston (Australia Telescope National Facility, CSIRO Space and Astronomy, PO Box 76, Epping NSW 1710, Australia)
3. Aris Karastergiou, Lucy S. Oswald, Bettina Posselt (Department of Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK)
4. Lucy S. Oswald (Magdalen College, University of Oxford, Oxford OX1 4AU, UK)
5. Bettina Posselt (Department of Astronomy & Astrophysics, Pennsylvania State University, 525 Davey Lab, 16802 University Park, PA, USA)
6. Xiaoxi Song (ASTRON, The Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD, Dwingeloo, The Netherlands)
7. Andrew D. Cameron (Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, VIC 3122, Australia)
8. Andrew D. Cameron (ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), Swinburne University of Technology, PO Box 218, VIC 3122, Australia)
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| Abstract : | The average pulse profile of a pulse serves as its fingerprint and is unique to every pulsar. A wealth of information about the pulsar magnetosphere is derived from its profile shape. For the majority of the pulsars, the average shape remains invariant over time. However, for very few sources variations in the profile shape have been observed. Sometimes these changes are correlated with the changes in the rotation of the pulsar, which gives insight into the dynamic nature of the magnetosphere. The MeerKAT monitoring data accrued over the last few years on ~500 pulsars under the MeerTIME's Thousand Pulsar Array (TPA) programme, has enabled the detection of subtle emission changes in seven sources not yet known to exhibit long-term profile evolution. These variations are theorised to originate from the magnetospheric state changes with associated current density variations.
Precession could play a role, and emission heights could be affected. In this talk, I will briefly describe the techniques adopted to measure the subtle changes in the emission state of the pulsar both in the total intensity and polarization domain and discuss how they are connected to the rotational evolution of the neutron stars. Further, I will elucidate how these measurements have been used to derive the limits on the various measurable parameters such as changes in the emission height, impact parameter of the line of sight, and changes in the magnetospheric charge density. |
