GMRT High Resolution Southern Sky survey

Main Image
GHRSS sky coverage and discoveries. Part of the target sky already covered with the survey is marked with deep blue shaded region. Part of the sky that is not yet covered is marked as light blue shaded region. (Image Credit: Shreya Umesh (NIUS student))

(Bhaswati Bhattacharyya, Jayanta Roy, Jayaram N. Chengalur, Sanjay Kudale, Ben Stappers (University of Manchester, UK), Mike Keith (University of Manchester, UK), Mateusz Malenta (University of Manchester), Sally Cooper (University of Manchester, UK))

GHRSS - GMRT High Resolution Southern Sky survey of pulsars and transients - is an ongoing off galactic plane survey with the GMRT. The sensitivity of the GMRT combined with the sophisticated and flexible software backend (GSB) makes it the premier instrument for searching for pulsars and extra-galactic radio bursts (FRBs) in the southern sky. The simultaneous time domain and imaging capability of this survey provides an unique opportunity of discovery and simultaneous localisation of pulsars and FRBs. GHRSS is an off the galactic plane (|b|>5) survey scanning a portion of sky having declination -40 to -54 at 322 MHz, i.e. declination complementary to other ongoing low frequency surveys with GBT and LOFAR. This portion of sky is not surveyed at frequencies less than 1.4 GHz for last two decade. This survey uses the high resolution survey modes in the GMRT software backend. The survey sensitivity is 0.5 mJy, which is comparable to the GBNCC surveys conducted with  GBT.  Phase-1 of the survey was funded by Marie Curie grant (PIIF-GA-2013-626533) of European Union of B. Bhattacharyya.  Till now in Phase-1 of the survey covering ∼ 1800 deg^2 of sky (∼62% of the total target sky), we have discovered 13 pulsars including a millisecond pulsar, two mildly recycled pulsars and a pulsar for which we also detect gamma-ray pulsation with Fermi LAT. We have developed a coherently-dedispersed gating correlator (coherently-dedispersed gating correlator - https://arxiv.org/abs/1302.1246) for rapid astrometry of newly discovered pulsars from this survey.
Image 2
Parameters for 27 discoveries from the GHRSS survey
 
Aided by the upgraded GMRT with increased sensitivity, we are starting Phase-2 part of the GHRSS survey with 200 MHz bandwidth. Calculated theoretical sensitivity for 10 mins pointing duration for the GHRSS Phase-2 at 400 MHz is 0.25 mJy. This is important as we start to probe the lower range of the pulsar luminosity distribution. The FRB fluence also improves to 1 Jy-ms in Phase-2 compared to 3 Jy-ms in Phase-1.  Identification of FRBs with host galaxies through simultaneous localisation using the GMRT interferometer can provide vital inputs in understanding the nature of the FRB phenomenon.
We have 14 discoveries from Phase-2, including one MSP and three RRATs. This includes RRAT discovered with the GMRT. The MSP is the first MSP discovered with the upgraded GMRT.
 
Following is the list of pulsars discovered with the GHRSS survey

Pulsar             Period        DM
                      (ms)         (pc/cc)
----------------------------------------
J0418-42         757.11       26.1 
J0514-44	      320.27       15.38
J0600-46         798.8         50.36 
J0703-50	      666.00        98.7 
J0919-42	      812.62        57.8
J0941-43         447.7         105.5 
J1023-43         454.35       62.5
J1239-48	      653.89       107.6
J1242-46         1411.2       76.5
J1243-47         5.31           78.6
J1255-46	      52.03          42.9 
J1428-42         234.70        66.0 
J1456-48	      533.81        133.0 
J1516-43	      36.02          70.25 
J1517-31         140.67        51.0
J1517-31         1103.67      61.7
J1559-44	      1169.89       122.0 
J1708-52	      449.62         102.7 
J1726-52	      631.84         119.7 
J1845-40         324.18         68.4 
J1845-40         373.48         47.8
J1936-30         1675.8         42.3
J1947-43	       180.94         29.9 
J2141-52	       5.04            19.6 

 
RRAT               Period        DM
                       (ms)         (pc/cc)
----------------------------------------
J1406−50          -              40
J1850-48   	327          23
J2004-38           -              23

Publications from GHRSS survey 
1) The GMRT High Resolution Southern Sky Survey for pulsars and transients -I. Survey description
and initial discoveries
Bhattacharyya, B., Cooper, S., Malenta, M., Roy, J., Chengalur, J. N., Keith, M, Kudale, S.,McLaughlin,
M., Ransom, S. M., Ray, P.S., Stappers B. W. et al., 2016, Astrophysical Journal, 817, 130
(https://arxiv.org/abs/1712.04518)

2) Search for pulsars and transients with the GMRT
Bhaswati Bhattacharyya (https://arxiv.org/abs/1712.04518)

3)Post-correlation beamformer for time-domain studies of pulsars and transients
 Jayanta Roy, Jayaram N. Chengalur, Ue-Li Pen
2018, ApJ, 864, 160
(https://arxiv.org/abs/1808.01088)

4) The GMRT High Resolution Southern Sky Survey for pulsars and transients -II. New discoveries, timing and polarization properties
B. Bhattacharyya, J. Roy, B. W. Stappers, T. Johnson, C. D. Ilie, A. Lyne, M. Malenta, P. Weltevrede, J. Chengalur, S. Cooper, B. Kaur, M. Keith, M. Kerr, S. Kudale, M. A. McLaughlin, S. M. Ransom, P. S. Ray 2019, ApJ, 811, 1 
(https://arxiv.org/abs/1906.09574)
Recent Results

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