| Name: | Anu Kundu |
| Affiliation: | Centre for Space Research, North-West University, Potchefstroom, South Africa |
| Conference ID : | ASI2024_630 |
| Title : | The multipolar magnetic field of NICER Millisecond Pulsar J0030+0451 |
| Authors : | Anu Kundu 1, Alice K. Harding 2, Constantinos Kalapotharakos 3, Demosthenes Kazanas 3, Christo Venter 1, Zorawar Wadiasingh 3,4
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| Authors Affiliation: | 1 Centre for Space Research, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa
2 Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 58545, USA
3 Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
4 Universities Space Research Association (USRA), Columbia, MD 21046, USA |
| Mode of Presentation: | Poster |
| Abstract Category : | High Energy Phenomena, Fundamental Physics and Astronomy |
| Abstract : | The Neutron star (NS) Interior Composition ExploreR (NICER) has been operating since 2017 to better understand the extreme nature of NSs. With its exceptional sensitivity and timing, its ultimate aim is to constrain the equation of state of NSs to better precision. Modelling thermal X-ray light curves (LCs) of pulsars can provide insights into their magnetic field structure and the morphology of their surface hot spots, leading to constraints on their mass and radius due to gravitational light bending effects.
Recent studies have strongly indicated the presence of a multipolar magnetic field for the millisecond pulsar PSR J0030+0451 (J0030) while also localising hot spots on its surface. Kalapotharakos et al. (2021) used an offset static dipole plus quadrupole magnetic field description to fit the NICER X-ray LCs of J0030. We have developed a code to implement a generic multipolar magnetic field expansion to constrain the field parameter space for J0030, adopting retarded vacuum field solutions (Pétri 2015), as opposed to previous works based on static fields, since these are closer to the more realistic force-free field configurations required to simultaneously explain and fit the gamma-ray LCs seen by Fermi-LAT. We consider all m = -l to l field components from l = 1 to l = 3, and employ Markov chain Monte Carlo (MCMC) methods to fit the bolometric X-ray LCs of J0030, and constrain the number of components and orientation of the field required for an adequate fitting.
We aim to eventually expand our parameter space by keeping the stellar mass and radius independent, and hence, putting more robust constraints on the equation of state. We present the methods of our approach, highlight the field configuration differences between different multipolar components, and show some preliminary fits for the thermal X-ray LC of J0030 discussing the optimal magnetic field configuration. |
