Upper Limits on X-ray Emission from Two Rotating Radio Transients - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate

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Abstract: X-ray emission from the enigmatic Rotating RAdio Transients RRATs offers avital clue to understanding these objects and how they relate to the greaterneutron star population. An X-ray counterpart to J1819-1458 is known, and itsproperties are similar to those of other middle-aged 0.1 Myr neutron stars.We have searched for X-ray emission with Chandra-ACIS at the positions of twoRRATs with arcsecond or better localisation, J0847-4316 and J1846-0257.Despite deep searches especially for J1847-0257 we did not detect anyemission with 0.3-8 keV count-rate limits of 1 counts-ks and 0.068 counts-ks,respectively, at 3sigma confidence. Assuming thermal emission similar to thatseen from J1819-1458 a blackbody with radius of approximately 20 km, wederive effective temperature limits of 77 eV and 91 eV for the nominal valuesof the distances and column densities to both sources, although both of thosequantities are highly uncertain and correlated. If we instead fix thetemperature of the emission a blackbody with kT=0.14 keV, we deriveunabsorbed luminosity limits in the 0.3-8 keV range of 1e32 erg-s and 3e32erg-s. These limits are considerably below the luminosity of J1819-1458 4e33erg-s, suggesting that RRATs J0847-4316 and J1846-0257 have cooled beyond thepoint of visibility plausible given the differences in characteristic age.However, as we have not detected X-ray emission, it may also be that theemission from RRATs J0847-4316 and J1846-0257 has a different character fromthat of J1819-1458. The two non-detections may prove a counterpoint toJ1819-1458, but more detections are certainly needed before we can begin toderive general X-ray emission properties for the RRAT populations.

Author: D. L. Kaplan, P. Esposito, S. Chatterjee, A. Possenti, M. A. McLaughlin, F. Camilo, D. Chakrabarty, P. O. Slane

Source: https://arxiv.org/

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