Born-Infeld magnetars: larger than classical toroidal magnetic fields and implications for gravitational-wave astronomy

Author(s)

Pereira, Jonas P. ^{[1, 2, 3]} ; Coelho, Jaziel G. ^{[4, 5]} ; de Lima, Rafael C. R. ^[6]

Affiliation

^[1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Ave Estados 5001, BR-09210170 Santo Andre, SP - Brazil

^[2] Univ Southampton, Math Sci, Southampton SO17 1BJ, Hants - England

^[3] Univ Southampton, STAG Res Ctr, Southampton SO17 1BJ, Hants - England

^[4] Inst Nacl Pesquisas Espaciais, Div Astrofis, Ave Astronautas 1758, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[5] Univ Tecnol Fed Parana, Dept Fis, BR-85884000 Medianeira, PR - Brazil

^[6] Univ Estado Santa Catarina, Av Madre Benvenuta 2007, BR-88035901 Florianopolis, SC - Brazil

• Document type: Journal article
• Source: EUROPEAN PHYSICAL JOURNAL C; v. 78, n. 5 MAY 8 2018.
• Web of Science Citations: 0

Abstract

Magnetars are neutron stars presenting bursts and outbursts of X- and soft-gamma rays that can be understood with the presence of very large magnetic fields. In this setting, nonlinear electrodynamics should be taken into account for a more accurate description of such compact systems. We study that in the context of ideal magnetohydrodynamics and make a realization of our analysis to the case of the well known Born-Infeld (BI) electromagnetism in order to come up with some of its astrophysical consequences. We focus here on toroidal magnetic fields as motivated by already known magnetars with low dipolar magnetic fields and their expected relevance in highly magnetized stars. We show that BI electrodynamics leads to larger toroidal magnetic fields when compared to Maxwell's electrodynamics. Hence, one should expect higher production of gravitational waves (GWs) and even more energetic giant flares from nonlinear stars. Given current constraints on BI's scale field, giant flare energetics and magnetic fields in magnetars, we also find that the maximum magnitude of magnetar ellipticities should be 10(-6)-10(-5) . Besides, BI electrodynamics may lead to a maximum increase of order 10-20% of the GW energy radiated from a magnetar when compared to Maxwell's, while much larger percentages may arise for other physically motivated scenarios. Thus, nonlinear theories of the electromagnetism might also be probed in the near future with the improvement of GW detectors. (AU)

• FAPESP's process: 17/21384-2 - Asteroseismology of quasi-periodic oscillations and constraints to hybrid neutron star models
• Grantee: Jonas Pedro Pereira
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 15/04174-9 - Some consequences of the microphysics of volumes and surfaces in compact systems
• Grantee: Jonas Pedro Pereira
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/26258-4 - Superdense matter in the universe
• Grantee: Manuel Máximo Bastos Malheiro de Oliveira
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 13/15088-0 - Magnetars and the highly magnetized, fast, very massive, strange white dwarfs pulsars, and the generation of gravitational waves
• Grantee: Jaziel Goulart Coelho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral