The birthrate of magnetars

Magnetars, neutron stars with ultrastrong magnetic fields (B similar to 10(14)-10(15) G), manifest their exotic nature in the form of soft gamma-ray repeaters and anomalous X-ray pulsars. This study estimates the birthrate of magnetars to be similar to 0.22 per century with a Galactic population comprising similar to 17 objects. A population synthesis was carried out based on the five anomalous X-ray pulsars detected in the ROSAT All Sky Survey by comparing their number to that of massive OB stars in a well-defined volume. Additionally, the group of seven X-ray dim isolated neutron stars detected in the same survey were found to have a birthrate of similar to 2 per century with a Galactic population of similar to 22 000 objects.