Variable scintillation arcs of millisecond pulsars observed with the Large European Array for Pulsars

Abstract

We present the first large sample of scintillation arcs in millisecond pulsars, analysing 12 sources observed with the Large European Array for Pulsars (LEAP), and the Effelsberg 100 m telescope. We estimate the delays from multipath propagation, measuring significant correlated changes in scattering timescales over a 10-year timespan. Many sources show compact concentrations of power in the secondary spectrum, which in PSRs J0613−0200 and J1600−3053 can be tracked between observations, and are consistent with compact scattering at fixed angular positions. Other sources such as PSRs J1643−1224 and J0621+1002 show diffuse, asymmetric arcs which are likely related to phase-gradients across the scattering screen. PSR B1937+21 shows at least three distinct screens which dominate at different times and evidence of varying screen axes or multi-screen interactions. We model annual and orbital arc curvature variations in PSR J0613−0200, providing a measurement of the longitude of ascending node, resolving the sense of the orbital inclination, where our best fit model is of a screen with variable axis of anisotropy over time, corresponding to changes in the scattering of the source. Unmodeled variations of the screen’s axis of anisotropy are likely to be a limiting factor in determining orbital parameters with scintillation, requiring careful consideration of variable screen properties, or independent VLBI measurements. Long-term scintillation studies such as this serve as a complementary tool to pulsar timing, to measure a source of correlated noise for pulsar timing arrays, solve pulsar orbits, and to understand the astrophysical origin of scattering screens.

The NANOGrav 12.5 yr Data Set: Search for Gravitational Wave Memory

“…Previous work has shown that scattering variations may result in excess correlated noise in pulsar timing data sets (Keith et al 2013;Chalumeau et al 2021;Goncharov et al 2021). In particular, Main et al (2020Main et al ( , 2023 have shown that data from PSR J0613−0200 show significant evidence of scattering variations. These scattering variations may be the source of the differences in GW memory upper limits in the vicinity of this pulsar when using different CURN spectral indices.…”

A Simultaneous Dual-frequency Scintillation Arc Survey of Six Bright Canonical Pulsars Using the Upgraded Giant Metrewave Radio Telescope

“…As a consequence, large surveys of scintillation arcs have typically focused on canonical (i.e., nonrecycled) pulsars with high flux densities and low dispersion measures (Stinebring et al 2022) or observations at low observing frequencies where pulsars are typically brightest (Wu et al 2022). Some recent large surveys have used newer, more sensitive instruments and observing configurations, in some cases detecting scintillation arcs in over 100 pulsars across a wide range of dispersion measures (Main et al 2023b), and in others performing large scintillation arc surveys using generally lower-flux-density millisecond pulsars (Main et al 2023a). Pulsar scintillometry, which uses observations of scintillation arcs over many years, has allowed for highprecision estimations on the localization of scattering screens along a given LOS (McKee et al 2022;Sprenger et al 2022).…”