Open AccessNon‐linear electrodynamics and the gravitational redshift of highly magnetized neutron stars
Author(s) -
Mosquera Cuesta Herman J.,
Salim José M.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08375.x
Subject(s) - physics , neutron star , pulsar , general relativity , gravitational redshift , redshift , astrophysics , gravitational field , gravitation , gravitational wave , radius , equation of state , classical mechanics , quantum mechanics , galaxy , computer security , computer science
We show that non‐linear electrodynamics (NLED) modifies in a fundamental basis the concept of gravitational redshift (GRS) as introduced by Einstein's theory of general relativity (GR). The effect becomes apparent when light propagation from super‐strongly magnetized compact objects, such as pulsars, is under focus. The analysis, here based on the (exact) non‐linear Lagrangian of Born & Infeld (1934), proves that unlike GR, where the GRS is independent of any background magnetic field ( B ‐field), when NLED is incorporated into the photon dynamics, an effective GRS appears, which happens to depend decidedly on the B ‐field pervading the pulsar. The resulting GRS tends to infinity as the B ‐field grows larger, as opposed to the Einstein prediction. As in astrophysics, the GRS is used to infer the mass–radius relation, and thus the equation of state (EOS) of a compact star (for example, a neutron star; Cottam et al. 2002). This unexpected GRS critical change may mislead observers into considering that fundamental property: the EOS. Hence, a correct procedure to estimate those crucial physical properties demands a neat separation of the NLED effects from the pure gravitational ones in the light emitted by ultra‐magnetized pulsars.