ИСТИНА

Neutron stars can appear as sources of different nature. In this paper we address observability of a hypothetical class of neutron stars — HOt and Fast Non Accreting Rotators, HOFNARs. These objects are heated due to the r-mode instability. With surface temperatures 10K they are expected to be thermal soft X-ray emitters. We perform a population synthesis modeling of HOFNARs to predict the number of potentially detectable sources in the eROSITA all-sky survey. For surface temperatures 10K we obtain 500 sources above the detection limit 0.01 cts s and 100 easier identifiable sources with cts s. Temperatures 1.2 10K start to be in contradiction with non-detection of HOFNARs by ROSAT. Only for numbers predicted for eROSITA turn out to be so low that identification does not look possible. We conclude that eROSITA has good chances to discover HOFNARs, if they exist. Non-detection will put very stringent limits on the properties of this type of neutron stars.