Where Are the R-modes? Chandra Observations of Millisecond Pulsars
Abstract
We present the results of Chandra observations of two non-accreting millisecond pulsars PSRs J1640+2224 (J1640) and J1709+2313(J1709), with low inferred magnetic fields in order to constrain their surface temperatures, obtain limits on the amplitude of unstable r-modes in them and make comparisons with similar limits obtained for a sample of accreting LMXB neutron stars (NSs). We detect both pulsars in the X-ray band for the first time. We found upper limits on the global surface temperature of these pulsars that are ∼ 3.3 × 10^5 - 4.7 × 10^5K. These sources are several Gyr old. In all standard cooling models NSs cool to surface temperatures less than 10^4K in less than 10^7 yr. While we derived upper limits on the surface temperatures of these sources, they appear to be consistent with the values measured for PSR J0437-4715 and J2124-3358. Taken together these results suggest that the surface temperatures of at least some MSPs are significantly higher, given their ages, than standard cooling models would suggest. For pulsars that are inside the r-mode instability window, r-mode dissipation can provide a potential source of reheating.
- Publication:
-
The X-ray Universe 2017
- Pub Date:
- October 2017
- Bibcode:
- 2017xru..conf..135M