Changing our understanding of the Universe with the SKA

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Planck

Changing our understanding of the Universe with the SKA

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Courtesy: SKAO

Journée SKA au LAM

Changing our understanding of the Universe with the SKA

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Pulsars and the SKA Michael Kramer

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Figure 1: Pulsar-related discoveries as a function of time. The time of the first SKA Science Book is markedand some important (selected) discoveries since are marked. The right panel puts the current numbers intoperspective with those expected for the SKA.

2. Science enabled by the discovery & study of pulsars and radio emitting neutronstars with the SKA

The pulsar key science described in the first SKA Science Book had a number of relatedcomponents, which were summarised under the theme of “Testing Gravity”. With pulsars beingstrongly self-gravitating bodies and precision clocks at the same time, timing observations of bi-nary and isolated millisecond pulsars allow unprecedented strong-field experiments. These includetesting general relativity and alternative theories of gravity using binary pulsars and (the yet to bediscovered) pulsar-black hole systems as well as the direct detection of gravitational waves usinga “Pulsar Timing Array” (PTA) experiment. Given the advances in recent years, prospects are nowdescribed in two separate chapters by Shao et al. (2015) and Janssen et al. (2015), respectively.In addition to those, we provide here a summary of the rich and varied science goals for the SKAdescribed in the appropriate chapters:

Chapter 37 — Gravitational wave astronomy with the SKA — Janssen et al. (2015) APulsar Timing Array (PTA) is used as a cosmic gravitational wave (GW) detector. As describedin the chapter by Janssen et al. (2015), Phase I essentially guarantees the direct detection of aGW signal. This may appear as a stochastic background from binary super-massive black holes inthe process of early galaxy evolution, or it may be bright individual source(s) of this kind. Exoticphenomena like cosmic strings may also be expected to produce measurable GW signals, shouldthey exist. The last ten years have seen a much better understanding of the source population, thedetection procedures and the use of a PTA for fundamental physics (such as graviton properties,e.g. Lee et al. 2010) or single source localisation capabilities (e.g. Lee et al. 2011), all of which isdescribed in the corresponding chapter.

Chapter 38 — Understanding pulsar magnetospheres with the SKA — Karastergiou etal. (2015) Considerable progress has been made with our understanding of the pulsar emissionmechanism in the last decade. However, the wide bandwidth and exceptional sensitivity of theSKA will revolutionise our understanding of radio emission from all types of radio emitting neu-

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Kramer & Stappers