The GMRT High resolution Southern Sky Survey for Pulsars and Transients. I. Survey Description and Initial Discoveries

Abstract

We are conducting a survey for pulsars and transients using the Giant Metrewave Radio Telescope (GMRT). The GMRT High Resolution Southern Sky (GHRSS) survey is an off-Galactic-plane (|b| > 5) survey in the declination range −40 • to −54 • at 322 MHz. With the high time (up to 30.72 µs) and frequency (up to 0.016275 MHz) resolution observing modes, the 5σ detection limit is 0.5 mJy for a 2 ms pulsar with 10% duty cycle at 322 MHz. Total GHRSS sky coverage of 2866 deg 2 , will result from 1953 pointings, each covering 1.8 deg 2 . The 10σ detection limit for a 5 ms transient burst is 1.6 Jy for the GHRSS survey. In addition, the GHRSS survey can reveal transient events like rotating radio transients or fast radio bursts. With 35% of the survey completed (i.e. 1000 deg 2 ), we report the discovery of 10 pulsars, one of which is a millisecond pulsar (MSP), one of the highest pulsar per square degree discovery rates for any off-Galactic plane survey. We re-detected 23 known in-beam pulsars. Utilising the imaging capability of the GMRT we also localised 4 of the GHRSS pulsars (including the MSP) in the gated image plane within ± 10 . We demonstrated rapid convergence in pulsar timing with a more precise position than is possible with single dish discoveries. We also exhibited that we can localise the brightest transient sources with simultaneously obtained lower time resolution imaging data, demonstrating a technique that may have application in the SKA.

A Post-correlation Beamformer for Time-domain Studies of Pulsars and Transients

“…This block includes removal of dispersion delay followed by a flagging and calibration pipeline and snapshot imaging. We note that part of this imaging pipeline to localise time-domain events has already been demonstrated for the GHRSS phase-1 survey (Bhattacharyya et al 2016).…”

“…The GMRT was one of the first interferometric instruments to be systematically used for pulsar searches. The high discovery rate of the GMRT High Resolution Southern Sky (GHRSS 12 ; Bhattacharyya et al (2016); Bhattacharyya (2017)) as well as the Fermi-directed survey (Bhatacharyya et al 2013) demonstrate the capabilities of the GMRT for low frequency pulsar searches. The recent upgrade of the GMRT allowing much larger instantaneous bandwidths (uGMRT; Gupta et al (2017)) brings a significant increase in its theoretical survey sensitivity for pulsars and FRBs at low and mid radio frequencies.…”

Super-knee Cosmic Rays from Galactic Neutron Star Merger Remnants

“…Note that the central remnant of GW170817 should be a black hole, because we do not observe the luminous X rays and high-energy gamma rays in later time from GW170817 (see Murase et al 2018 for related discussions). The magnetar model will be examined by the counterpart searches of GWs (see Abbott et al 2017b, and references therein) and transient searches in the radio band (Hales 2013;Bhattacharyya et al 2016;Fender et al 2017).…”

The LOFAR Tied-Array All-Sky Survey (LOTAAS): Survey overview and initial pulsar discoveries

“…An ongoing, full-sky 350-MHz survey with the GBT, the GBNCC, has found 160 pulsars to date (Stovall et al 2014;Kawash et al 2018;Lynch et al 2018). An ongoing driftscan survey with Arecibo at 327 MHz has found 82 pulsars 3 (AO327; Deneva et al 2013), while the GMRT High Resolution Southern Sky (GHRSS; Bhattacharyya et al 2016) survey discovered 10 pulsars at 322 MHz in the Southern sky (−54 • < δ < −40 • ). Targeted low-frequency searches of unidentified Fermi gammaray sources have also discovered 62 millisecond pulsars (e.g.…”