COHERENTLY DEDISPERSED GATED IMAGING OF MILLISECOND PULSARS
Abstract
Motivated by the need for rapid localization of newly discovered faint millisecond pulsars (MSPs), we have developed a coherently dedispersed gating correlator. This gating correlator accounts for the orbital motions of MSPs in binaries while folding the visibilities with a best-fit topocentric rotational model derived from a periodicity search in a simultaneously generated beamformer output. Unique applications of the gating correlator for sensitive interferometric studies of MSPs are illustrated using the Giant Metrewave Radio Telescope (GMRT) interferometric array. We could unambiguously localize five newly discovered Fermi MSPs in the on-off gated image plane with an accuracy of {+-}1''. Immediate knowledge of such a precise position enables the use of sensitive coherent beams of array telescopes for follow-up timing observations which substantially reduces the use of telescope time ({approx}20 Multiplication-Sign for the GMRT). In addition, a precise a priori astrometric position reduces the effect of large covariances in the timing fit (with discovery position, pulsar period derivative, and an unknown binary model), which in-turn accelerates the convergence to the initial timing model. For example, while fitting with the precise a priori position ({+-}1''), the timing model converges in about 100 days, accounting for the effect of covariance between the position andmore »
- Authors:
-
- National Centre for Radio Astrophysics, Pune 411007 (India)
- Publication Date:
- OSTI Identifier:
- 22130821
- Resource Type:
- Journal Article
- Journal Name:
- Astrophysical Journal Letters
- Additional Journal Information:
- Journal Volume: 765; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCOUNTING; ACCURACY; BEAMS; CALIBRATION; CONVERGENCE; IMAGES; PERIODICITY; PULSARS; QUANTUM DECOHERENCE; RADIO TELESCOPES; SENSITIVITY
Citation Formats
Roy, Jayanta, and Bhattacharyya, Bhaswati. COHERENTLY DEDISPERSED GATED IMAGING OF MILLISECOND PULSARS. United States: N. p., 2013.
Web. doi:10.1088/2041-8205/765/2/L45.
Roy, Jayanta, & Bhattacharyya, Bhaswati. COHERENTLY DEDISPERSED GATED IMAGING OF MILLISECOND PULSARS. United States. https://doi.org/10.1088/2041-8205/765/2/L45
Roy, Jayanta, and Bhattacharyya, Bhaswati. 2013.
"COHERENTLY DEDISPERSED GATED IMAGING OF MILLISECOND PULSARS". United States. https://doi.org/10.1088/2041-8205/765/2/L45.
@article{osti_22130821,
title = {COHERENTLY DEDISPERSED GATED IMAGING OF MILLISECOND PULSARS},
author = {Roy, Jayanta and Bhattacharyya, Bhaswati},
abstractNote = {Motivated by the need for rapid localization of newly discovered faint millisecond pulsars (MSPs), we have developed a coherently dedispersed gating correlator. This gating correlator accounts for the orbital motions of MSPs in binaries while folding the visibilities with a best-fit topocentric rotational model derived from a periodicity search in a simultaneously generated beamformer output. Unique applications of the gating correlator for sensitive interferometric studies of MSPs are illustrated using the Giant Metrewave Radio Telescope (GMRT) interferometric array. We could unambiguously localize five newly discovered Fermi MSPs in the on-off gated image plane with an accuracy of {+-}1''. Immediate knowledge of such a precise position enables the use of sensitive coherent beams of array telescopes for follow-up timing observations which substantially reduces the use of telescope time ({approx}20 Multiplication-Sign for the GMRT). In addition, a precise a priori astrometric position reduces the effect of large covariances in the timing fit (with discovery position, pulsar period derivative, and an unknown binary model), which in-turn accelerates the convergence to the initial timing model. For example, while fitting with the precise a priori position ({+-}1''), the timing model converges in about 100 days, accounting for the effect of covariance between the position and pulsar period derivative. Moreover, such accurate positions allow for rapid identification of pulsar counterparts at other wave bands. We also report a new methodology of in-beam phase calibration using the on-off gated image of the target pulsar, which provides optimal sensitivity of the coherent array removing possible temporal and spacial decoherences.},
doi = {10.1088/2041-8205/765/2/L45},
url = {https://www.osti.gov/biblio/22130821},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 765,
place = {United States},
year = {Sun Mar 10 00:00:00 EST 2013},
month = {Sun Mar 10 00:00:00 EST 2013}
}