Timing and scintillation of a young Galactic halo pulsar

Abstract

We present a timing and scintillation study of the young Galactic halo pulsar PSR J1740+1000 using observations from the Nanshan, FAST, and Parkes radio telescopes. From timing analysis, we measure the pulsar's proper motion for the first time, indicating motion away from the Galactic plane at a position angle of 16.7 +/- 4.8 degrees (Galactic coordinates), with a total proper motion of 56.9 +/- 8.0 mas/yr and a corresponding transverse velocity of 329 +/- 80 km/s. This velocity suggests that PSR J1740+1000 is a typical-velocity young pulsar born within the Galactic halo. In scintillation studies, we detect scintillation arcs, arclets, and double-layered adjacent arcs in the secondary spectra. Under isotropic and anisotropic scattering assumptions, the screen-to-pulsar distance is 370 +/- 72 pc and 1 +/- 12 pc, respectively. The latter closely matches the scale of the pulsar wind nebula associated with PSR J1740+1000 and provides a better fit, suggesting that scattering is likely dominated by the PWN. The double-layered adjacent arcs observed on MJD 60180 imply that the pulsar's scattered image consists of two dominant components (A and B) and multiple weaker components. Component A is located at the pulsar's geometric position (0 uas), while Component B is located 112 +/- 16 uas and 23 +/- 17 uas from the central component under isotropic and anisotropic scattering, respectively. The frequency-independent angular position of Component B hints at refraction by an AU-scale structure within the scattering region, possibly originating from the PWN.

Figures (19)

• Figure 1: The position of PSR J1740+1000 at MJDs 51662, 55384 and 59711. The blue points represent positions derived from AO observations, the cyan points represent positions obtained from the first segment of Nanshan data, and the red points represent positions derived from the second segment of Nanshan data combined with FAST observations. The black lines indicate the best-fit results.
• Figure 2: The dynamic spectra from twelve observations of PSR J1740+1000 using FAST centered at 1250 MHz.
• Figure 3: The dynamic spectra from four observations of PSR J1740+1000 using Parkes centered at 1369 MHz.
• Figure 4: The ACF of PSR J1740+1000 on MJD 59510 at 1375 MHz. Panel a: the 2D ACF. Panel b: the corresponding 1D frequency-domain ACF. Panel c: the corresponding 1D time-domain ACF.
• Figure 5: Secondary spectra for PSR J1740+1000 from twelve FAST observations. The red dash lines represent the best-fit arc curvature cetered at 1100 MHz.