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Sign of Hard-X-Ray Pulsation from the γ -Ray Binary System LS 5039
Takahashi, T.; Enoto, T.; Makishima, K. +3 more
To understand the nature of the brightest γ -ray binary system LS 5039, hard x-ray data of the object, taken with the Suzaku and NuSTAR observatories in 2007 and 2016, respectively, were analyzed. The two data sets jointly gave tentative evidence for a hard x-ray periodicity, with a period of ∼9 s and a period increase rate by ∼3 ×10-10…
X-Ray Signatures of Axion Conversion in Magnetic White Dwarf Stars
Safdi, Benjamin R.; Dessert, Christopher; Long, Andrew J.
White dwarf (WD) stars may radiate keV-energy axions produced in their stellar cores. This has been extensively studied as an extra channel by which WDs may cool, with some analyses even suggesting that axions can help explain the observed WD luminosity function. We show that the radiated axions may convert into x rays in the strong magnetic field…
Possible Evidence for Free Precession of a Strongly Magnetized Neutron Star in the Magnetar 4U 0142+61
Hiraga, J. S.; Enoto, T.; Murakami, H. +5 more
Magnetars are a special type of neutron stars, considered to have extreme dipole magnetic fields reaching ∼1011 T. The magnetar 4U 0142+61, one of the prototypes of this class, was studied in broadband x rays (0.5-70 keV) with the Suzaku observatory. In hard x rays (15-40 keV), its 8.69 sec pulsations suffered slow phase modulations by …