A real-time software backend for the GMRT

Roy, Jayanta; Gupta, Yashwant; Pen, Ue-Li; Peterson, Jeffrey B.; Kudale, Sanjay; Kodilkar, Jitendra

doi:10.1007/s10686-010-9187-0

Cited by 99 publications

(89 citation statements)

References 11 publications

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“…This shows how proper foreground removal remains a challenge. Removal of RFI, compensation for ionospheric disturbances, proper calibration of radio sources etc., are among the major challenges that the GMRT faces currently though efforts are ongoing to overcome some of the hurdles (Roy et al 2010;.…”

Section: Selected Results From Ska Precursors and Pathfindersmentioning

confidence: 99%

Reionization and the Cosmic Dawn with the Square Kilometre Array

et al. 2013

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The Square Kilometre Array (SKA) will have a low frequency component (SKA-low) which has as one of its main science goals the study of the redshifted 21cm line from the earliest phases of star and galaxy formation in the Universe. This 21cm signal provides a new and unique window both on the time of the formation of the first stars and accreting black holes and the subsequent period of substantial ionization of the intergalactic medium. The signal will teach us fundamental new things about the earliest phases of structure formation, cosmology and even has the potential to lead to the discovery of new physical phenomena. Here we present a white paper with an Executive SummaryThe Square Kilometre Array (SKA) will have a low frequency component (AA-low/SKA-low 1 ) which has as one of its main science goals the study of the redshifted 21cm line from the earliest phases of star and galaxy formation in the Universe (see SKA Memo 125). It is during this phase that the first building blocks of the galaxies that we see around us today, including our own Milky Way, were formed. It is a crucial period for understanding the history of the Universe and one for which we have currently very little observational data.We divide the period into two different phases based on the physical processes which affect the Intergalactic Medium. The first period, which we call the Cosmic Dawn, saw the formation of the first stars and accreting black holes, which changed the quantum state of the still neutral Intergalactic Medium. The second period, known as the Epoch of Reionization, is the one during which large areas between the galaxies were photo-ionized by the radiation produced in galaxies and which ended when the Intergalactic Medium had become completely ionized.Observations of the redshifted 21-cm line with SKA will provide a new and unique window on the entire period of Cosmic Dawn and Reionization. The signal is sensitive to the emergence of the first stellar populations, radiation from growing massive black holes and the formation of larger groups of galaxies and bright quasars. At the same time it maps the distribution of most of the baryonic matter in the Universe. The study of the redshifted 21cm line will teach us fundamental new things about the earliest phases of structure formation and cosmology. It even has the potential to lead to the discovery of new physical phenomena. Here we present an overview of the science questions that SKA-low can address, how we plan to tackle these questions and what this implies for the basic design of the telescope.The redshifted 21cm signal will be analyzed with different techniques, which each come with their own requirements for the SKA: (i) Tomography, (ii) power-spectra and higher-order statistics, (iii) hydrogen absorption, (iv) global/total-intensity signal. Whereas all precursors/pathfinders aim to study the signal statistically through its power spectrum, SKA will be able to image the neutral hydrogen distribution directly and its focus will therefore be more on tomograph...

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Section: Selected Results From Ska Precursors and Pathfindersmentioning

confidence: 99%

Reionization and the Cosmic Dawn with the Square Kilometre Array

et al. 2013

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“…Both these modes are described in Roy et al (2010). The frequency range was from 1371 MHz to 1404 MHz.…”

Section: A2 Giant Meterwave Radio Telescopementioning

confidence: 99%

A 24 Hr Global Campaign to Assess Precision Timing of the Millisecond Pulsar J1713+0747

Dolch

Lam

Cordes

et al. 2014

ApJ

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General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 08 May 2018The Astrophysical Journal, 794:21 (14pp), 2014 October 10 doi:10.1088/0004-637X/794/1/21 C 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. A 24 HR GLOBAL CAMPAIGN TO ASSESS PRECISION TIMING OF THE MILLISECOND PULSAR J1713+0747 ABSTRACTThe radio millisecond pulsar J1713+0747 is regarded as one of the highest-precision clocks in the sky and is regularly timed for the purpose of detecting gravitational waves. The International Pulsar Timing Array Collaboration undertook a 24 hr global observation of PSR J1713+0747 in an effort to better quantify sources of timing noise in this pulsar, particularly on intermediate (1-24 hr) timescales. We observed the pulsar continuously over 24 hr with the Arecibo, Effelsberg, GMRT, Green Bank, LOFAR, Lovell, Nançay, Parkes, and WSRT radio telescopes. The combined pulse times-of-arrival presented here provide an estimate of what sources of timing noise, excluding DM variations, would be present as compared to an idealized √ N improvement in timing precision, where N is the number of pulses analyzed. In the case of this particular pulsar, we find that intrinsic pulse phase jitter dominates arrival time precision when the signal-to-noise ratio of single pulses exceeds unity, as measured using the eight telescopes that observed at L band/1.4 GHz. We present first results of specific phenomena probed on the unusually long timescale (for a single continuous observing session) of tens of hours, in particular interstellar scintillation, and discuss the degree to which scintillation and profile evolution affect precision timing. This paper presents the data set as a basis for future, deeper studies.

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“…VLA observations of Abell 523 were taken in D-array. We also included archival observations from project AB1180 (Lband D and C-array Roy et al 2010) was used.…”

Section: Radio Observationsmentioning

confidence: 99%

Radio continuum observations of new radio halos and relics from the NVSS and WENSS surveys

Weeren

Brüggen

Röttgering

et al. 2011

A&A

118

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Context. Radio halos and relics are diffuse radio sources found in galaxy clusters showing significant substructure at X-ray wavelengths. These sources provide important information about non-thermal processes taking place in the intracluster medium (ICM). Until now only a few dozen relics and halos are known, while models predict that a much larger number of these sources exist. In this paper we present the results of an extensive observing campaign to search for new diffuse radio sources in galaxy clusters. Aims. The aim of the observations is to create a large sample of diffuse radio sources in galaxy clusters that help to understand the formation of radio relics and halos and can be used to probe the physical conditions of the ICM. Methods. We carried out radio continuum observations with the Westerbork Synthese Radio Telescope (WSRT), Giant Metrewave Radio Telescope (GMRT) and Very Large Array (VLA) of clusters with diffuse radio emission visible in NVSS and WENSS survey images. Optical images were taken with the William Herschel and Isaac Newton Telescope (WHT, INT). Results. We discovered 6 new radio relics, including a probable double relic system, and 2 radio halos. In addition, we confirm the presence of diffuse radio emission in four galaxy clusters. By constructing a sample of 35 radio relics we find that relics are mostly found along the major axis of the X-ray emission from the ICM, while their orientation is perpendicular to this axis. We also compared the X-ray luminosity and redshift distributions of clusters with relics to an X-ray selected sample from the NORAS and REFLEX surveys. We find tentative evidence for an increase of the cluster's relic fraction with X-ray luminosity and redshift. The major and minor axis ratio distribution of the ICM for clusters with relics is broader than that of the NORAS-REFLEX sample. Conclusions. The location and orientation of radio relics with respect to the ICM elongation is consistent with the scenario that relics trace merger shock waves.

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A real-time software backend for the GMRT

Cited by 99 publications

References 11 publications

Reionization and the Cosmic Dawn with the Square Kilometre Array

Reionization and the Cosmic Dawn with the Square Kilometre Array

A 24 Hr Global Campaign to Assess Precision Timing of the Millisecond Pulsar J1713+0747

Radio continuum observations of new radio halos and relics from the NVSS and WENSS surveys

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