3.55 keV Silicon Anomaly as X-ray Candle in the Universe

Abstract

The Ly-$\alpha$ line of $^{14}$Si with the energy 3.55-keV is formed in the magnetic field $6\cdot 10^{12}$ G. In close binary stellar systems with a red giant and a neutron star in super-strong magnetic fields recombination laser radiation to the Landau ground level may appear from hydrogen-like ions. If the 3.55-keV Ly-$\alpha$ silicon laser realizes, then the detection of this line from any distances in the Universe on $z\leq100$ is possible and this line may be the X-ray candle because of a huge abundance of silicon in these binary systems. Energies for a Ly-$\alpha$ line of hydrogen-like $^{14}$Si in magnetic fields $4\cdot10^{12}-10^{13}$ G are calculated. This line is the unique event because we see this radiation from perpendicular direction to the magnetic column in near-wall layers. The laser radiation to the ground level in the range of (1-20) keV may arise from other hydrogen-like ions. In the presence of a laser, line narrowing is inevitable.