New approaches for the real-time detection of binary pulsars with the Square Kilometre Array (SKA)

The Square Kilometre Array (SKA) project is responsible for developing the SKA Observatory, the world’s largest radio telescope, with eventually over a square kilometre of collecting area and including a general headquarters as well as two radio telescopes: SKA1-Mid in South Africa and SKA1-Low in Australia. The SKA project consists of a number of subsystems (elements) among which the Telescope Manager (TM) is the one involved in controlling and monitoring the SKA telescopes. The TM element has three primary responsibilities: management of astronomical observations, management of telescope hardware and software subsystems, management of data to support system operations and all stakeholders (operators, maintainers, engineers and science users) in achieving operational, maintenance and engineering goals. Operators, maintainers, engineers and science users will interact with TM via appropriate user interfaces (UI). The TM UI framework envisaged is a complete set of general technical solutions (components, technologies and design information) for implementing a generic computing system (UI platform). Such a system will enable UI components to be instantiated to allow for human interaction via screens, keyboards, mouse and to implement the necessary logic for acquiring or deriving the information needed for interaction. It will provide libraries and specific Application Programming Interfaces (APIs) to implement operator and engineer interactive interfaces. This paper will provide a status update of the TM UI framework, UI platform and UI components design effort, including the technology choices, and discuss key challenges in the TM UI architecture, as well as our approaches to addressing them.

Pulsar search is one of the main tasks for the Square Kilometre Array (SKA) central signal processor (CSP) sub-element. Because most of the pulsar details are unknown, many pulsar search approaches are employed. The main compute-intensive application of the pulsar search modules is the matched filter group, which convolves the input signals with a group of filters. High-performance designs on FPGAs have been proposed that can process multiple large filters efficiently. But given that in many applications, including the here targeted pulsar search, filters have different sizes, there is a high potential for optimisation. This paper investigates the optimisation of general matched filtering design for the SKA pulsar search engine. The influence of changing the number of filters and the difference in sizes is analysed. The general implementations in time-domain (TD) and frequency-domain (FD) are optimised, employing the longest processing time (LPT) first rule to distribute filter templates across filter processing pipelines. The proposed design is employed to implement the matched filter groups in two SKA pulsar modules. The results show that the optimisation can provide up to 2.1x speedup in TD and 1.2x speedup in FD.

The next generation interferometric radio telescope, the Square Kilometre Array (SKA), which will be the most sensitive and largest radio telescope ever constructed, could greatly contribute to the detection, survey and characterization of Gamma Ray Bursts (GRBs). By the SKA, it will be possible to perform the follow up of GRBs even for several months. This approach would be extremely useful to extend the Spectrum Energetic Distribution (SED) from the gamma to the to radio band and would increase the number of radio detectable GRBs. In principle, the SKA could help to understand the physics of GRBs by setting constraints on theoretical models. This goal could be achieved by taking into account multiple observations at different wavelengths in order to obtain a deeper insight of the sources. Here, we present an estimation of GRB radio detections, showing that the GRBs can really be observed by the SKA. The approach that we present consists in determining blind detection rates derived by a very large sample consisting of merging several GRB catalogues observed by current missions as Swift, Fermi, Agile and INTEGRAL and by previous missions as BeppoSAX, CGRO, GRANAT, HETE-2, Ulysses and Wind. The final catalogue counts 7516 distinct sources. We compute the fraction of GRBs that could be observed by the SKA at high and low frequencies, above its observable sky. Considering the planned SKA sensitivity and through an extrapolation based on previous works and observations, we deduce the minimum fluence in the range 15-150 keV. This is the energy interval where a GRB should emit to be detectable in the radio band by the SKA. Results seem consistent with observational capabilities.

In this work, we investigate what role the redshift-drift data of the Square Kilometre Array (SKA) will play in the cosmological parameter estimation in the future. To test the constraint capability of the redshift-drift data of SKA-only, the Lambda CDM model is chosen as a reference model. We find that using the SKA1 mock data, the Lambda CDM model can be loosely constrained, while the model can be well constrained when the SKA2 mock data are used. When the mock data of SKA are combined with the data of the European Extremely Large Telescope (E-ELT), the constraints can be significantly improved, becoming almost as good as the data combination of the type Ia supernovae observation (SN), the cosmic microwave background observation (CMB), and the baryon acoustic oscillations observation (BAO). Furthermore, we explore the impact of the redshift-drift data of SKA on the basis of SN+CMB+BAO+E-ELT in the Lambda CDM model, the wCDM model, the CPL model, and the HDE model. We find that the redshift-drift measurement of SKA could help to significantly improve the constraints on dark energy and could break the degeneracy between the cosmological parameters. Therefore, we conclude that redshift-drift observation of SKA would provide a good improvement in the cosmological parameter estimation in the future and has the enormous potential to be one of the most competitive cosmological probes in constraining dark energy.

Fast radio bursts (FRBs) are mysterious extragalactic radio signals. Revealing their origin is one of the central foci in modern astronomy. Previous studies suggest that occurrence rates of non-repeating and repeating FRBs could be controlled by the cosmic stellar-mass density (CSMD) and cosmic star formation-rate density (CSFRD), respectively. The Square Kilometre Array (SKA) is one of the best future instruments to address this subject due to its high sensitivity and high-angular resolution. Here, we predict the number of FRBs to be detected with the SKA. In contrast to previous predictions, we estimate the detections of non-repeating and repeating FRBs separately, based on latest observational constraints on their physical properties including the spectral indices, FRB luminosity functions, and their redshift evolutions. We consider two cases of redshift evolution of FRB luminosity functions following either the CSMD or CSFRD. At $z$ ≳ 2, $z$ ≳ 6, and $z$ ≳ 10, non-repeating FRBs will be detected with the SKA at a rate of ∼104, ∼102, and ∼10 (sky−1 d−1), respectively, if their luminosity function follows the CSMD evolution. At $z$ ≳ 1, $z$ ≳ 2, and $z$ ≳ 4, sources of repeating FRBs will be detected at a rate of ∼103, ∼102, and ≲10 (sky−1 d−1), respectively, assuming that the redshift evolution of their luminosity function is scaled with the CSFRD. These numbers could change by about one order of magnitude depending on the assumptions on the CSMD and CSFRD. In all cases, abundant FRBs will be detected by the SKA, which will further constrain the luminosity functions and number density evolutions.

As the scientific exploitation of the Square Kilometre Array (SKA) approaches, there is a need for new advanced data analysis and visualization tools capable of processing large high-dimensional datasets. In this study, we aim to generalize the YOLO-CIANNA deep learning source detection and characterization method for 3D hyperspectral HI emission cubes. We present the adaptations we made to the regression-based detection formalism and the construction of an end-to-end 3D convolutional neural network (CNN) backbone. We then describe a processing pipeline for applying the method to simulated 3D HI cubes from the SKA Observatory Science Data Challenge 2 (SDC2) dataset. The YOLO-CIANNA method was originally developed and used by the MINERVA team that won the official SDC2 competition. Despite the public release of the full SDC2 dataset, no published result has yet surpassed MINERVA's top score. In this paper, we present an updated version of our method that improves our challenge score by 9.5%. The resulting catalog exhibits a high detection purity of 92.3%, best-in-class characterization accuracy, and contains 45% more confirmed sources than concurrent classical detection tools. The method is also computationally efficient, processing the full ∼1TB SDC2 data cube in 30 min on a single GPU. These state-of-the-art results highlight the effectiveness of 3D CNN-based detectors for processing large hyperspectral data cubes and represent a promising step toward applying YOLO-CIANNA to observational data from SKA and its precursors.

The Square Kilometre Array (SKA) Observatory is gearing up the formal construction of its two radio interferometers in Australia and South Africa after the end of design and pre-construction phases. Agile methodologies, the Cloud native Computing technologies and the DevOps software ideas are influencing the design of compute infrastructures that will be key to reduce the operational costs of SKA while improving the control and monitoring of the SKA antennas and ancillary systems, Correlators, HPC facilities or related data centre tiered systems. These tools will likely include advanced power metering technologies and efficient distribution automation and Network Operation Centres (NOC). SKA will become the world's largest radio telescope and is expected to achieve its first science by 2026. To cope with this dimension and complexity, a key part of this distributed Observatory is the overall software control and monitoring system embodied in the Observatory Management and Control (OMC) and the Services Teams that requires specialized Agile Teams to assist in software and cyber infrastructure building using an Agile development environment that includes test automation, Continuous Integration, and Continuous Deployment. To manage such a large and distributed machine, the Agile approach was adopted for the core software package of the SKA Telescope aimed at scheduling observations, controlling their execution, monitoring the telescope status and ensuring scalability and reliability. Here, we report on the ENGAGE SKA ciberinfrastructure prototyping support to the SKA Agile Software Development Life Cycle (SDLC).

Large scale radio astronomy (RA) activity, brought to focus in South Africa with the Square Kilometre Array (SKA) developments, only began to impact on local engineering teams from around 2004. The country's first demonstrator was ready for evaluation towards the end of 2007. It was at that point that my EMRIN group's engagement on radio frequency interference (RFI) began. After a review of a number of European RA sites, and doing some calculations of required electromagnetic quietness required for viable SKA observations, it became apparent that RFI management would be a major priority for any contemporary large radio research instruments. This talk will discuss components of site development that are now considered essential for any such instruments to be regarded as robust. The presentation will review: 1. Electromagnetic compatibility (EMC) principles illustrated with simple schematic experiments and computational electromagnetics. The pictorial material will emphasise an understanding of current paths, resistive, E and B-field coupling mechanisms and then the use of enclosures, interfaces and cabling structures [1-3]. Some suitable sensors and their calibration will be described [4-6]. 2. Various radio astronomy observatories (RAO's) that have been visited in Europe and South Africa which will be considered in the light of these principles. 3. Experience gained from the South African experimental demonstrator model (XDM), the Karoo Array Telescopes (KAT-7 and MeerKAT) and some Square Kilometre Array (SKA) precursor lower-frequency arrays [7-21]. 4. Requirements for designing robust large radio research instruments where challenges for these large science projects will be posed. The two primary purposes of the presentation will be to: a) promote the viewpoint that site and instrument construction must embrace EMC principles from the start, and b) encourage the interaction of engineers, scientists and astronomers throughout the development process.

The Square Kilometre Array (SKA), when it becomes functional, is expected to enrich neutron star (NS) catalogues by at least an order of magnitude over their current state. This includes the discovery of new NS objects leading to better sampling of under-represented NS categories, precision measurements of intrinsic properties such as spin period and magnetic field, as also data on related phenomena such as microstructure, nulling, glitching, etc. This will present a unique opportunity to seek answers to interesting and fundamental questions about the extreme physics underlying these exotic objects in the universe. In this paper, we first present a meta-analysis (from a methodological viewpoint) of statistical analyses performed using existing NS data, with a two-fold goal: First, this should bring out how statistical models and methods are shaped and dictated by the science problem being addressed. Second, it is hoped that these analyses will provide useful starting points for deeper analyses involving richer data from SKA whenever it becomes available. We also describe a few other areas of NS science which we believe will benefit from SKA which are of interest to the Indian NS community.

We consider a decaying scalar dark matter (DM) with mass $m_\chi$ in the range 10 GeV - 10 TeV and vary the branching ratios of all possible two-body SM final states (excluding and including $\nu\bar{\nu}$) in the range $0\%-100\%$ to derive constraints on the total decay width $\Gamma$ using the data collected by several astrophysical and cosmological observations. We find that, $\Gamma \lesssim 10^{-26} - 10^{-27}\,{\rm s}^{-1}$ (excluding $\nu\bar{\nu}$) and $\Gamma \lesssim 10^{-24} - 10^{-26}\,{\rm s}^{-1}$ (including $\nu\bar{\nu}$) are allowed, depending on the values of $m_\chi$, which are most robust upper limits on $\Gamma$ for a generic decaying scalar DM. We then investigate the prospect of the upcoming Square Kilometre Array (SKA) radio telescope in detecting the DM decay induced radio signals originating inside the dwarf spheroidal (dSph) galaxies. We have classified the DM parameter space, allowed by the existing observations, independently of the branching ratio of each individual two-body SM final state, based on the detectability at the SKA. Excluding the $\nu\bar{\nu}$ decay mode, we find that, throughout the DM mass range considered, $\Gamma \gtrsim 10^{-30}\,{\rm s}^{-1} - 10^{-29}\,{\rm s}^{-1}$ is detectable for all possible branching ratio combinations at the SKA (assuming 100 hours of observation time), with conservative choices for the relevant astrophysical parameters. On the other hand, when arbitrary branching ratios are allowed also for the $\nu\bar{\nu}$ decay mode, DM decays can be probed independently of the branching ratio of each SM final state for $\Gamma \gtrsim 2 \times 10^{-29}\,{\rm s}^{-1}$, provided DM masses are greater than a few hundreds of GeV.

The Square Kilometre Array (SKA), a flagship 21st-century radio astronomy project [1], necessitates a global distributed network of SKA Regional Centres (SRCs) to address its unprecedented data processing, storage, and distribution needs [2,3].The China SKA Regional Centre (cnSRC) is under development as a critical component of the international SRCNet, this system architecture is designed to flexibly support both High-Performance-Computing (HPC) and Kubernetes container orchestration, enable scientific data access for the Chinese and broader international astronomy communities [4].This presentation provides and overview of the cnSRC's current status, cncompassing its computing infrastructure, data processing capabilities, data management and distribution strategies, scientific research priorities, and user support services [3].We introduce the cnSRC's architecture, strategy, and implementation progress, focusing on the deployment of federated computing models, high-speed networking solutions, and scalable data management systems.Furthermore, we discuss the development of the software framework and data pipelines designed to support SKA workflows, including data ingestion, processing, visualization, and user interaction.By aligning with SKA's global SRC architecture and policies, cnSRC aims to provide a robust and efficient platform for enabling SKA science in China and beyond.We also highlight the robust collaborative framework emerging among Asia-Pacific SKA Regional Centres, with a particular focus on the strong partnership between China and Australia in advancing radio astronomy, demonstrating the region's collective commitment.

This study presents the findings of using the Square Kilometre Array (SKA) telescope to measure redshift drift via the H i 21 cm signal, employing semiannual observational intervals within a redshift of around z ∼ 1 with a main goal of directly gauging the Universe’s expansion acceleration rate with mm s−1 precision. The SKA can detect over 1 billion H i 21 cm emissions from individual galaxies to redshift z ∼ 2 and thousands of absorption lines from damped Lyα systems against bright quasars to redshift z ∼ 13 with a sensitivity limit of 100 mJy. By utilizing SKA’s high spectral resolution settings (0.001, 0.002, 0.005, 0.01 Hz) to detect redshift drift, particularly focusing on the 0.001 and 0.002 Hz configuration, one aims to achieve the necessary mm s−1 in precision measurement by the 0.5 yr observation period. The velocity drift rate, crucially determined by the two operational regimes within 0.01–0.21 mm s−1 and 0.031–0.17 mm s−1, exceeds the theoretical accuracy limit of 1.28 mm s−1. The analysis thoroughly restricts cosmological parameters related to dark energy using the Sandage–Loeb (SL) signal from the H i 21 cm emission and absorption lines. It estimates a H 0 of about 70 km s−1 Mpc−1, Ωm near 0.3, and w close to −1, w 0 around −1, and wa approaching −0.1. These results strongly endorse the SL effect as an effective method for confirming cosmic acceleration and exploring the dark sector in real-time cosmology with the SKA.

Current imaging observations of protoplanetary disks using the Atacama Large Millimeter/submillimeter Array (ALMA) primarily focus on the submillimeter wavelength, leaving a gap in effective observational approaches for centimeter-sized dust, which is crucial to the issue of planet formation. The forthcoming Square Kilometre Array (SKA) and ngVLA may rectify this deficiency. In this paper, we employ multifluid hydrodynamic numerical simulations and radiative transfer calculations to investigate the potential of SKA1-Mid, ngVLA, and SKA2 for imaging protoplanetary disks at subcentimeter/centimeter wavelengths. We create mock images with ALMA/SKA/ngVLA at multiwavelengths based on the hydrodynamical simulation output and test different sensitivity and spatial resolutions. We discover that both SKA and ngVLA will serve as excellent supplements to the existing observational range of ALMA, and their high resolution enables them to image substructures in the disk’s inner region (∼5 au from the stellar). Our results indicate that SKA and ngVLA can be utilized for more extended monitoring programs in the centimeter wave band. While in the subcentimeter range, ngVLA possesses the capability to produce high-fidelity images within shorter observation times (∼1 hr on source time) than previous research, holding potential for future survey observations. We also discuss for the first time the potential of SKA2 for observing protoplanetary disks at a 0.7 cm wavelength.

One of the five key science projects for the Square Kilometre Array (SKA) is “The Origin and Evolution of Cosmic Magnetism”, in which radio polarimetry will be used to reveal what cosmic magnets look like and what role they have played in the evolving Universe. Many of the SKA prototypes now being built are also targeting magnetic fields and polarimetry as key science areas. Here I review the prospects for innovative new polarimetry and Faraday rotation experiments with forthcoming facilities such as ASKAP, LOFAR, the ATA, the EVLA, and ultimately the SKA. Sensitive wide-field polarisation surveys with these telescopes will provide a dramatic new view of magnetic fields in the Milky Way, in nearby galaxies and clusters, and in the high-redshift Universe.

One of the major science goals of square kilometre array (SKA) is to understand the role played by atomic hydrogen (Hi) gas in the evolution of galaxies throughout cosmic time. The hyperfine transition line of the hydrogen atom at 21-cm is one of the best tools to detect and study the properties of Hi gas associated with galaxies. In this paper, we review our current understanding of Hi gas and its relationship with galaxies through observations of the 21-cm line both in emission and absorption. In addition, we provide an overview of the Hi science that will be possible with SKA and its precursors and pathfinders, i.e., Hi 21-cm emission and absorption studies of galaxies from nearby to high redshifts that will trace various processes governing galaxy evolution.