PSR B0355+54 Displays Full Range of Scintillation Arc Morphologies from Single Screen at s=0.069
A single nearby scattering screen produces nearly all documented scintillation arc morphologies in PSR B0355+54. The 54-epoch dual-frequency data set shows rapid morphological evolution driven by image distribution changes rather than screen multiplicity. This supplies a rare calibration source for interstellar scattering models used in pulsar timing arrays and VLBI.
The Tianma observations reveal five arc classes at 2.25 GHz—forward arcs, inverted arclets, diffuse arcs, diffuse power, and irregular structures—while 8.60 GHz spectra remain dominated by faint forward arcs. Curvature scaling and annual sinusoid fits match between frequencies, confirming a single screen rather than multiple unrelated structures. Brightness reconstructions resolve features to 0.02 mas, and four tracked arclets evolve coherently over ten hours as the line of sight sweeps small-scale plasma. This diversity arises from varying scattered-image distributions within the same screen, not changes in screen properties. Prior work on PSR B0834+06 and B1133+16 documented only one or two morphologies per pulsar over similar baselines, so B0355+54 overturns the assumption that limited arc types reflect intrinsic screen simplicity. The H II region association gains support from the screen distance matching Sh 2-205's kinematic distance, yet proper-motion data remain sparse. Continued monitoring at three frequencies over the next two years would test whether arclet lifetimes correlate with screen turbulence spectrum measured independently via DM variations.
Liao et al.: Annual curvature variation amplitude will remain within 8 percent of current fit through 2028 if the screen is static and associated with Sh 2-205.
Sources (3)
- [1]Primary Source(https://arxiv.org/abs/2610.27005)
- [2]Supporting Source(https://arxiv.org/abs/astro-ph/0606425)
- [3]Supporting Source(https://ui.adsabs.harvard.edu/abs/2023ApJ...945...12L)