Speaker
Description
Making precise measurements of pulsar dispersion measures (DMs) and applying suitable corrections for them is one of the major challenges in pulsar timing arrays (PTAs). While the advent of wide-band pulsar instrumentation can enable more precise DM measurements and thence improved timing precision, it also necessitates careful assessments of frequency-dependent (chromatic) DMs that was theorised by Cordes et al. (2016). We present the detection of such an effect in our broadband observations of the millisecond pulsar PSR J2241-5236, a high-priority target for current and future PTAs. The observations were made contemporaneously using the wide-band receiver capabilities now available at the Murchison Widefield Array (MWA), the upgraded Giant Metrewave Radio Telescope (uGMRT), and the Parkes (Murriyang) telescopes, thus providing an unprecedentedly large frequency coverage from 80 MHz to 4032 MHz. Our analysis has revealed measurable changes in DMs that scale with the observing frequency. We discuss the potential implications of such a frequency dependence in the measured DMs, and the likely impact on the timing noise budget, and comment on the usefulness of low-frequency observations for advancing PTA efforts.
| Presentation length | 20 minutes |
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| Keynote presentation | yes |
