The SKA pulsar search pipeline will be used for real time detection of pulsars. Modern radio telescopes such as SKA will be generating petabytes of data in their full scale of operation. Hence experience-based and data-driven algorithms become indispensable for applications such as candidate detection. Here we describe our findings from testing a state of the art object detection algorithm called Mask R-CNN to detect candidate signatures in the SKA pulsar search pipeline. We have trained the Mask R-CNN model to detect candidate images. A custom annotation tool was developed to mark the regions of interest in large datasets efficiently. We have successfully demonstrated this algorithm by detecting candidate signatures on a simulation dataset. The paper presents details of this work with a highlight on the future prospects.
The Square Kilometre Array will be an amazing instrument for pulsar astronomy. While the full SKA will be sensitive enough to detect all pulsars in the Galaxy visible from Earth, already with SKA1, pulsar searches will discover enough pulsars to increase the currently known population by a factor of four, no doubt including a range of amazing unknown sources. Real time processing is needed to deal with the 60 PB of pulsar search data collected per day, using a signal processing pipeline required to perform more than 10 POps. Here we present the suggested design of the pulsar search engine for …
There are two types of timing irregularities seen in pulsars: glitches and timing noise. Both of these phenomena can help us probe the interior of such exotic objects. This article presents a brief overview of the observational and theoretical aspects of pulsar timing irregularities and the main results from the investigations of these phenomena in India. The relevance of such Indian programs for monitoring of young pulsars with the Square Kilometer Array (SKA) is presented, highlighting possible contributions of the Indian neutron star community to the upcoming SKA endeavour.
50-250 MHz Pulsar Census with an SKA-Low prototype station: Spectra and Polarization
International Centre for Radio Astronomy Research, Curtin University（国际射电天文研究中心，科廷大学）；SKAO, Science Operations Centre, CSIRO ARRC（平方公里阵列望远镜组织，科学运营中心，CSIRO ARRC）
Trinity College Dublin（都柏林三一学院）；Royal Holloway, University of London（伦敦大学皇家霍洛威学院）；University of Manchester（曼彻斯特大学）；Curtin University（科廷大学）；Université d’Orléans（奥尔良大学）；CNRS（法国国家科学研究中心）；Institute of Space Sciences (CSIC-ICE)（空间科学研究所（CSIC-ICE））；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚空间研究研究所（IEEC））；ASTRON, the Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
Prospects for Discovering Pulsars in Future Continuum Surveys Using Variance Imaging
在Dai等人（2016）中，我们开发了一种形式主义，用于从包含时间和频率信息的标准干涉无线电图像计算方差图像。方差成像与未来的无线电连续调查，使我们能够识别无线电脉冲星，并作为一个补充，传统的脉冲星搜索是最敏感的严格的周期性信号。在这里，我们进行模拟来预测我们可以在未来的连续调查中使用方差成像发现的卫星数量。我们表明，澳大利亚SKA探路者（ASKAP）的宇宙进化图（EMU）调查可以发现$\sim30$正常的恒星和$\sim40$毫秒恒星（MSP）超过和超过今天已知的数量，同样的，一个全天空连续调查与SKA-MID可以发现$\sim140$正常的恒星和$\sim110$ MSP与此技术。EMU和SKA-MID的方差成像将检测具有大占空比的双星，因此是在相对论双星系统中寻找MSP和双星的潜在工具。与目前在南半球银河系高纬度地区进行的脉冲星调查相比，EMU和SKA-MID的方差成像将更加灵敏，并将能够探测色散测量值在$\sim10$和100 cm $^{-3}$ pc之间的脉冲星。
Supermassive black holes are commonly found in the center of galaxies and evolve with their hosts. The supermassive binary black holes (SMBBH) are thus expected to exist in close galaxy pairs, however, none has been unequivocally detected. The square kilometre array (SKA) is a multi-purpose radio telescope with a collecting area approaching 1 million square metres, with great potential for detecting nanohertz gravitational waves (GWs). In this paper, we quantify the GW detectability by SKA for a realistic SMBBH population using pulsar timing array (PTA) technique and quantify its impact on rev…
FPGA-based Matched Filter Group Optimisation for SKA Pulsar Search Engine
PARC Lab, University of Auckland（奥克兰大学）；Jodrell Bank Centre for Astrophysics, University of Manchester（曼彻斯特大学）；Raman Research Institute, University of Manchester（曼彻斯特大学拉曼研究所）
Decades long monitoring of millisecond pulsars, which exhibit highly stable rotational periods, in pulsar timing array experiments is on the threshold of discovering nanohertz stochastic gravitational wave background. This paper describes the Indian Pulsar timing array (InPTA) experiment, which employs the upgraded Giant Metrewave Radio Telescope (uGMRT) for timing an ensemble of millisecond pulsars for this purpose. We highlight InPTA's observation strategies and analysis methods, which are relevant for a future PTA experiment with the more sensitive Square Kilometer Array (SKA) telescope. We…
Understanding the Neutron Star Population with the SKAO telescopes
The University of Manchester（曼彻斯特大学）；The Institute of Mathematical Sciences（数学科学研究所）；Homi Bhabha National Institute（霍米·巴巴国立学院）；INAF – Osservatorio Astronomico di Cagliari（意大利国家天体物理研究所卡利亚里天文台）；Swinburne University of Technology（斯威本科技大学）；Royal Holloway, University of London（伦敦大学皇家霍洛威学院）；Newcastle University（纽卡斯尔大学）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；West Virginia University（西弗吉尼亚大学）；University of Oxford（牛津大学）；Raman Research Institute（拉曼研究所）；Institute of Space Sciences (ICE-CSIC)（空间科学研究所）；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚空间研究学院）
FIP-TOI: Fast Imaging Pipeline for Pulsar Localisation with a Transient-Oriented Radio Astronomical Imager
University of Oxford（牛津大学）；Silesian University in Opava（奥帕瓦西里西亚大学）；Mila - Québec Artificial Intelligence Institute（米拉-魁北克人工智能研究所）；University of Cambridge（剑桥大学）；Special Astrophysical Observatory of the Russian Academy of Sciences（俄罗斯科学院特别天体物理观测站）
This paper presents the High-Performance computing efforts with FPGA for the accelerated pulsar/transient search for the SKA. Case studies are presented from within SKA and pathfinder telescopes highlighting future opportunities. It reviews the scenario that has shifted from offline processing of the radio telescope data to digitizing several hundreds/thousands of antenna outputs over huge bandwidths, forming several 100s of beams, and processing the data in the SKA real-time pulsar search pipelines. A brief account of the different architectures of the accelerators, primarily the new generati…
Pulsar data analysis pipelines have historically been comprised of bespoke software systems, supporting the off-line analysis of data. However modern data acquisition systems are making off-line analyses impractical. They often output multiple simultaneous high volume data streams, significantly increasing data capture rates. This leads to the accumulation of large data volumes, which are prohibitively expensive to retain. To maintain processing capabilities when off-line analysis becomes infeasible due to cost, requires a shift to on-line data processing. This paper makes four contributions f…
The Southern-sky MWA Rapid Two-metre (SMART) pulsar survey--IV. Survey update and an atlas of 205 non-recycled southern pulsars
International Centre for Radio Astronomy Research, Curtin University（国际射电天文研究中心，科廷大学）；Australian SKA Regional Centre (AusSRC), Curtin University（澳大利亚SKA区域中心（AusSRC），科廷大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；CSIRO Astronomy and Space Science（CSIRO天文学与空间科学）；National Radio Astronomy Observatory（美国国家射电天文台）；Manly Astrophysics（曼利天体物理学）
The upgraded GMRT (uGMRT) with its unprecedented sensitivity and high figure of merit, is expected to result in the discovery of a large population of pulsars including pulsars of previously unknown type. In the phase-2 of the GMRT High Resolution Southern Sky (GHRSS) survey with the uGMRT we will reach 1/4th of sensitivity of the SKA Phase-1. In this paper we highlight the salient features of the survey of pulsars and fast transients with the uGMRT highlighting its discovery potential. The extended GMRT (eGMRT) equipped with wide field- of-view, increased collecting area will have unprecedent…
Using the Fourier Domain Acceleration Search (FDAS) method to search for binary pulsars is a computationally costly process. Next generation radio telescopes will have to perform FDAS in real time, as data volumes are too large to store. FDAS is a matched filtering approach for searching time-domain radio astronomy datasets for the signatures of binary pulsars with approximately linear acceleration. In this paper we will explore how we have reduced the energy cost of an SKA-like implementation of FDAS in AstroAccelerate, utilising a combination of mixed-precision computing and dynamic frequenc…
This paper details on the discovery of 21 pulsars using the Giant Metrewave Radio Telescope (GMRT) from targeted (Fermi directed search) and blind surveys (GMRT High Resolution Southern Sky - GHRSS) and results from the follow up studies. We discovered seven millisecond pulsars (MSPs) in the Fermi directed searches, which are the first Galactic MSPs discovered with the GMRT. We have discovered 13 pulsars (including a MSP and two mildly recycled pulsars) with the GHRSS survey, which is an off-Galactic-plane survey at 322 MHz with complementary target sky (declination range -40 deg to -54 deg) t…
The sensitivity of ongoing searches for gravitational wave (GW) sources in the ultra-low frequency regime ($10^{-9}$ Hz to $10^{-7}$ Hz) using Pulsar Timing Arrays (PTAs) will continue to increase in the future as more well-timed pulsars are added to the arrays. It is expected that next-generation radio telescopes, namely, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) and the Square Kilometer Array (SKA), will grow the number of well-timed pulsars to $O(10^3)$. The higher sensitivity will result in greater distance reach for GW sources, uncovering multiple resolvable GW sour…
Gravitational wave (GW) searches using pulsar timing arrays (PTAs) are assumed to be limited by the typical average observational cadence of $1/(2~{\rm weeks})$ for a single pulsar to GW frequencies $\lesssim 4\times 10^{-7}$ Hz. We show that this assumption is incorrect and that a PTA can detect signals with much higher frequencies, which are preserved in the data due to aliasing, by exploiting asynchronous observations from multiple pulsars. This allows an observation strategy that is scalable to future large-scale PTAs containing $O(10^3)$ pulsars, enabled by the Five-hundred meter Aperture…
Pulsar timing arrays (PTAs) can be used to detect and study gravitational waves in the nanohertz band (i.e., wavelengths of order light-years). This requires high-precision, decades-long data sets from sensitive, instrumentally stable telescopes. NANOGrav and its collaborators in the International Pulsar Timing Array consortium are on the verge of the first detection of the stochastic background produced by supermassive binary black holes, which form via the mergers of massive galaxies. By providing Northern hemisphere sky coverage with exquisite sensitivity and higher frequency coverage compa…
Pulsar timing array experiments have recently reported strong evidence for a common-spectrum stochastic process with a strain spectral index consistent with that expected of a nanohertz-frequency gravitational-wave background, but with negligible yet non-zero evidence for spatial correlations required for a definitive detection. However, it was pointed out by the Parkes Pulsar Timing Array (PPTA) collaboration that the same models used in recent analyses resulted in strong evidence for a common-spectrum process in simulations where none is present. In this work, we introduce a methodology to d…
Pulsars have proven instrumental in exploring a wide variety of physics. Pulsars at low radio frequencies is crucial to further our understanding of spectral properties and emission mechanisms.The Murchison Widefield Array Voltage Capture System (MWA-VCS) has been routinely used to study and discover pulsars at low frequencies, offering the unique opportunity of recording complex voltages ,which can be off-line beamformed or imaged at millisecond time resolution.Devising imaged-based methods for finding pulsar candidates, which can be verified in beamformed data, can accelerate the complete pr…
Glitches are the observational manifestations of superfluidity inside neutron stars. The aim of this paper is to describe an automated glitch detection pipeline, which can alert the observers on possible real-time detection of rotational glitches in pulsars. Post alert, the pulsars can be monitored at a higher cadence to measure the post-glitch recovery phase. Two algorithms namely, Median Absolute Deviation (MAD) and polynomial regression have been explored to detect glitches in real time. The pipeline has been optimized with the help of simulated timing residuals for both the algorithms. Bas…
Enhancing VLBI Capability with the SKA-Mid and the Jingdong 120-m Radio Telescope
Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；State Key Laboratory of Radio Astronomy and Technology, Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台射电天文与技术重点实验室）；Chalmers University of Technology（查尔姆斯理工大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Nanjing University（南京大学）
