Continued support for the SKA as priority infrastructure

[manishacaleb]

The Australian Government recognises astronomy as a flagship science and there has been significant financial investment for the Square Kilometre Array (SKA). LOFAR is currently the best low frequency array in the world and SKA-Low in WA will have 25% better resolution and 8 times better sensitivity. Redshifted 21cm line emission will become the most important probe of galaxy and structure formation during early times, and the SKA will be the most sensitive instrument for characterising the power spectrum of brightness temperature fluctuations and for the first time directly make tomographic data cubes of the actual fluctuations out to the redshifts when the first galaxies formed.

Another exciting development is the possibility of having the advanced LIGO and VIRGO gravitational wave detectors operating at the same time as the SKA. The increased volume of the Universe which these detectors will be sensitive to almost guarantees that they will make direct detections of gravitational waves in the near future. The positional accuracy will still be relatively poor, but the wide field and rapid slewing capabilities becomes very important, allowing for the possibility of detecting the electromagnetic counterpart to the gravitational wave source.

Additionally, a number of long-period radio transients are being discovered in image plane surveys and Australia is currently leading the field. The SKA could be crucial in discovering many more of these and possibly even understanding the origins.

[ethrane]

I strongly support this as an infrastructure priority. In addition to all of the compelling science listed in @manishacaleb's post, SKA and SKA precursors play a crucial role in pulsar timing, which allows us to study supermassive black holes with nanohertz gravitational waves and to study ultra relativistic pulsar binary systems.

[manishacaleb]

Not to mention fast radio bursts (FRBs), which are currently one of the hottest topics in astronomy :) Australia/ASKAP is the world leader when it comes to well-localised FRBs.

[cwjames1983]

It's also worthwhile adding here that transient discovery is not driven by the raw sensitivity of the telescope, but the backend that does the transient processing. So we need to keep our eye on the ball here to ensure the SKA can be used efficiently.

[nhurleywalker]

I'd also add that LOFAR is only "the best" by certain metrics (raw sensitivity, resolution). The MWA has a wider field-of-view and that is one of the key metrics for transient discovery. It also has more filled instantaneous (u,v)-coverage which makes a big difference in the detectability of image-plane transients. In the Galactic plane, the Dutch array and the MWA have comparable sensitivity due to the deconvolution challenges of LOFAR data. The MWA also has a wider bandwidth which makes it easier to detect sources at 200MHz where scattering is lower, and characterise the dispersion of pulses. Similarly, while ASKAP has lower sensitivity than MeerKAT, its instantaneous field-of-view is wider.

We should support these facilities, which will still be active for years to decades, as they give Australian astronomers unique capabilities which will not be superseded until full completion of the SKA Phase 1 (~2029). The Southern Hemispehre locations make this particularly important for Galactic transients, and deep-sky wide-field observations without the contaminants of Cyg A and Cas A.

See also @cwjames1983 comment: https://github.com/ethrane/transients/issues/17#issue-2204748781

Note also Ramesh Bhat makes an excellent point about the SKA precursors transferring lessons to the use and science cases for the SKA itself.