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Title: DETECTION OF FAST TRANSIENTS WITH RADIO INTERFEROMETRIC ARRAYS

Abstract

Next-generation radio arrays, including the Square Kilometre Array (SKA) and its pathfinders, will open up new avenues for exciting transient science at radio wavelengths. Their innovative designs, comprising a large number of small elements, pose several challenges in digital processing and optimal observing strategies. The Giant Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for developing and validating suitable observing modes and strategies for transient experiments with future arrays. Here we describe the first phase of the ongoing development of a transient detection system for GMRT that is planned to eventually function in a commensal mode with other observing programs. It capitalizes on the GMRT's interferometric and sub-array capabilities, and the versatility of a new software backend. We outline considerations in the plan and design of transient exploration programs with interferometric arrays, and describe a pilot survey that was undertaken to aid in the development of algorithms and associated analysis software. This survey was conducted at 325 and 610 MHz, and covered 360 deg{sup 2} of the sky with short dwell times. It provides large volumes of real data that can be used to test the efficacies of various algorithms and observing strategies applicable for transient detection. We present examplesmore » that illustrate the methodologies of detecting short-duration transients, including the use of sub-arrays for higher resilience to spurious events of terrestrial origin, localization of candidate events via imaging, and the use of a phased array for improved signal detection and confirmation. In addition to demonstrating applications of interferometric arrays for fast transient exploration, our efforts mark important steps in the roadmap toward SKA-era science.« less

Authors:
 [1]; ; ; ; ;  [2]; ; ; ;  [3]
  1. International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia)
  2. National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411007 (India)
  3. Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, Victoria 3122 (Australia)
Publication Date:
OSTI Identifier:
22156546
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 206; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALGORITHMS; COMPUTER CODES; DESIGN; DETECTION; EXPLORATION; INTERFEROMETERS; MHZ RANGE 100-1000; PULSARS; RADIO TELESCOPES; SIGNALS; SKY; TRANSIENTS

Citation Formats

Bhat, N. D. R., Chengalur, J. N., Gupta, Y., Prasad, J., Roy, J., Kudale, S. S., Cox, P. J., Bailes, M., Burke-Spolaor, S., and Van Straten, W. DETECTION OF FAST TRANSIENTS WITH RADIO INTERFEROMETRIC ARRAYS. United States: N. p., 2013. Web. doi:10.1088/0067-0049/206/1/2.
Bhat, N. D. R., Chengalur, J. N., Gupta, Y., Prasad, J., Roy, J., Kudale, S. S., Cox, P. J., Bailes, M., Burke-Spolaor, S., & Van Straten, W. DETECTION OF FAST TRANSIENTS WITH RADIO INTERFEROMETRIC ARRAYS. United States. doi:10.1088/0067-0049/206/1/2.
Bhat, N. D. R., Chengalur, J. N., Gupta, Y., Prasad, J., Roy, J., Kudale, S. S., Cox, P. J., Bailes, M., Burke-Spolaor, S., and Van Straten, W. 2013. "DETECTION OF FAST TRANSIENTS WITH RADIO INTERFEROMETRIC ARRAYS". United States. doi:10.1088/0067-0049/206/1/2.
@article{osti_22156546,
title = {DETECTION OF FAST TRANSIENTS WITH RADIO INTERFEROMETRIC ARRAYS},
author = {Bhat, N. D. R. and Chengalur, J. N. and Gupta, Y. and Prasad, J. and Roy, J. and Kudale, S. S. and Cox, P. J. and Bailes, M. and Burke-Spolaor, S. and Van Straten, W.},
abstractNote = {Next-generation radio arrays, including the Square Kilometre Array (SKA) and its pathfinders, will open up new avenues for exciting transient science at radio wavelengths. Their innovative designs, comprising a large number of small elements, pose several challenges in digital processing and optimal observing strategies. The Giant Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for developing and validating suitable observing modes and strategies for transient experiments with future arrays. Here we describe the first phase of the ongoing development of a transient detection system for GMRT that is planned to eventually function in a commensal mode with other observing programs. It capitalizes on the GMRT's interferometric and sub-array capabilities, and the versatility of a new software backend. We outline considerations in the plan and design of transient exploration programs with interferometric arrays, and describe a pilot survey that was undertaken to aid in the development of algorithms and associated analysis software. This survey was conducted at 325 and 610 MHz, and covered 360 deg{sup 2} of the sky with short dwell times. It provides large volumes of real data that can be used to test the efficacies of various algorithms and observing strategies applicable for transient detection. We present examples that illustrate the methodologies of detecting short-duration transients, including the use of sub-arrays for higher resilience to spurious events of terrestrial origin, localization of candidate events via imaging, and the use of a phased array for improved signal detection and confirmation. In addition to demonstrating applications of interferometric arrays for fast transient exploration, our efforts mark important steps in the roadmap toward SKA-era science.},
doi = {10.1088/0067-0049/206/1/2},
journal = {Astrophysical Journal, Supplement Series},
number = 1,
volume = 206,
place = {United States},
year = 2013,
month = 5
}
  • We relate the underlying properties of a population of fast radio-emitting transient events to its expected detection rate in a survey of finite sensitivity. The distribution of the distances of the detected events is determined in terms of the population luminosity distribution and survey parameters, for both extragalactic and Galactic populations. The detection rate as a function of Galactic position is examined to identify regions that optimize survey efficiency in a survey whose field of view is limited. The impact of temporal smearing caused by scattering in the interstellar medium has a large and direction-dependent bearing on the detection ofmore » impulsive signals, and we present a model for the effects of scattering on the detection rate. We show that the detection rate scales as {Omega}S{sup -3/2+{delta}}{sub 0}, where {Omega} is the field of view, S{sub 0} is the minimum detectable flux density, and 0 < {delta} {<=} 3/2 for a survey of Galactic transients in which interstellar scattering or the finite volume of the Galaxy is important. We derive formal conditions on the optimal survey strategy to adopt under different circumstances for fast transient surveys on next generation large-element, wide-field arrays, such as ASKAP, LOFAR, the MWA, and the SKA, and show how interstellar scattering and the finite spatial extent of a Galactic population modify the choice of optimal strategy.« less
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