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arXiv · 2206.07957

Observability of HOFNARs with SRG/eROSITA

A. D. Khokhriakova·A. I. Chugunov·S. B. Popov·M. E. Gusakov·E. M. Kantor
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Abstract

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 $\sim 10^6$~K 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 $\sim 10^6$~K we obtain $\sim 500$ sources above the detection limit 0.01~cts~s$^{-1}$ and $\sim 100$ easier identifiable sources with $>0.1$~cts~s$^{-1}$. Temperatures $\gtrsim 1.2\times 10^6$~K start to be in contradiction with non-detection of HOFNARs by ROSAT. Only for $T\lesssim 5\times 10^5$~K 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.

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A. D. Khokhriakova, A. I. Chugunov, S. B. Popov, M. E. Gusakov, E. M. Kantor. 2022-06-16. Observability of HOFNARs with SRG/eROSITA. https://doi.org/10.3390/universe8070354

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