Justin G. Elfritz | Searcharxiv

arXiv2026

FORTVSH: A Fortran Library For Vector Spherical Harmonics Computations

The vector spherical harmonics (VSH) are crucial ingredients for representation of arbitrary vector fields in curvilinear coordinate systems throughout mathematical physics. Performant, efficient computations of the VSH are essential to high-performance computing applications that utilize spectral analysis, including magnetohydrodynamics (MHD) simulations for geophysics and astrophysics. The free open-source FORTVSH library provides a catalog of numerical routines for evaluating various VSH forms and related mathematical functions. This manuscript establishes the theoretical basis, addresses the computational need for efficient VSH solvers, and presents a comprehensive overview of the FORTVSH routines.

astro-ph.SR↗

arXiv2018

Discovery of X-rays from the old and faint pulsar J1154--6250

We report on the first X-ray observation of the 0.28 s isolated radio pulsar PSR J1154--6250 obtained with the XMM-Newton observatory in February 2018. A point-like source is firmly detected at a position consistent with that of PSR J1154--6250. The two closest stars are outside the 3$σ$ confidence limits of the source position and thus unlikely to be responsible for the observed X-ray emission. The energy spectrum of the source can be fitted equally well either with an absorbed power-law with a steep photon index $Γ\approx 3.3$ or with an absorbed blackbody with temperature $kT=0.21\pm 0.04$~keV and emitting radius $R_\mathrm{BB} \approx 80$ m (assuming a distance of 1.36~kpc). The X-ray luminosity of $4.4\times 10^{30}$ erg s$^{-1}$ derived with the power-law fit corresponds to an efficiency of $η_X = L^\mathrm{unabs}_X/\dot E = 4.5\times 10^{-3}$, similar to those of other old pulsars. The X-ray properties of PSR J1154--6250 are consistent with an old age and suggest that the spatial coincidence of this pulsar with the OB association Cru OB1 is due to a chance alignment.

astro-ph.HE↗