The Square Kilometre Array (SKA)

Abstract:

PSR J0901−4046, a likely radio-loud neutron star with a period of 75.88 s, challenges conventional models of neutron star radio emission. Here, we showcase results from 46 h of follow-up observations of PSR J0901−4046 using the MeerKAT, Murriyang, Giant Metrewave Radio Telescope, and Murchison Widefield Array radio telescopes. We demonstrate the intriguing stability of the source’s timing solution over more than 3 yr, leading to an RMS arrival-time uncertainty of just of the rotation period. Furthermore, non-detection below 500 MHz may indicate a low-frequency turnover in the source’s spectrum, while no secular decline in the flux density of the source over time, as was apparent from previous observations, has been observed. Using high time-resolution MeerKAT data, we demonstrate two distinct quasi-periodic oscillation modes present in single pulses, with characteristic time-scales of 73 and 21 ms. We also observe a statistically significant change in the relative prevalence of distinct pulse morphologies compared to previous observations, possibly indicating a shift in the magnetospheric composition over time. Finally, we show that the W pulse width is nearly constant from 544 to 4032 MHz, consistent with zero radius-to-frequency mapping. The very short duty cycle () is more similar to radio pulsars with periods >5 s than to radio-loud magnetars. This, along with the lack of magnetar-like outbursts or timing glitches, complicates the identification of the source with ultralong period magnetar models.

Abstract:

We present the Evolutionary Map of the Universe (EMU) survey conducted with the Australian Square Kilometre Array Pathfinder (ASKAP). EMU aims to deliver the touchstone radio atlas of the southern hemisphere. We introduce EMU and review its science drivers and key science goals, updated and tailored to the current ASKAP five-year survey plan. The development of the survey strategy and planned sky coverage is presented, along with the operational aspects of the survey and associated data analysis, together with a selection of diagnostics demonstrating the imaging quality and data characteristics. We give a general description of the value-added data pipeline and data products before concluding with a discussion of links to other surveys and projects and an outline of EMU’s legacy value.