| Author(s) and Co-Author(s) with Affiliation: Jyotirmoy Das(National Centre for Radio Astrophysics (NCRA), Pune-411007, India), Jayanta Roy(National Centre for Radio Astrophysics (NCRA), Pune-411007, India), Paulo C. C. Freire(Max-Planck-Institut für Radioastronomie (MPIfR), Auf dem Hügel 69-53121, Bonn, Germany), Scott Ransom(National Radio Astronomy Observatory (NRAO), Charlottesville, Virginia, United States), Bhaswati Bhattacharyya(National Centre for Radio Astrophysics (NCRA), Pune-411007, Maharashtra, India), Karel Adamek(Department of Physics, Silesian University in Opava, Opava, 74601, Czech Republic), Wes Armour(Oxford e-Research Centre (OeRC) University of Oxford, Oxford-OX13PJ, United Kingdom), Sanjay Kudale(National Centre for Radio Astrophysics (NCRA), Pune-411007, Maharashtra, India), Mekhala V. Muley(Giant Metrewave Radio Telescope (GMRT), Khodad, Pune- 410504, Maharashtra, India) |
| Abstract: Globular clusters (GCs) are dense stellar environments known to efficiently produce millisecond pulsars (MSPs) through frequent stellar interactions. Leveraging the enhanced sensitivity of the upgraded Giant Metrewave Radio Telescope (uGMRT) phased array beam and the steep radio spectra of MSPs, we initiated the Globular Clusters GMRT Pulsar Search (GCGPS) in the 300-750 MHz range (uGMRT Band 3 and Band 4), a largely underexplored frequency regime for GC MSP searches having a complementary sky coverage to the FAST.
To date, GCGPS has discovered seven new MSPs across four globular clusters, none of which had previously known pulsars. This represents the most successful pulsar search in globular clusters conducted with the GMRT. These discoveries have provided precise dispersion measures for the host clusters and revealed a diverse set of systems, including one isolated MSP and one in a moderately compact binary with an orbital period of ~1.56 days, likely an eclipsing redback system with a relatively long orbital period. One particularly interesting system is a highly eccentric relativistic binary with an orbital period of ~19 hours and an eccentricity of ~0.54. For this compact system, we were able to measure a post-Keplerian (PK) parameter, which allowed for a direct estimate of the total system mass.
In this talk, we will present an overview of the GCGPS survey, highlight recent discoveries, and present results from the timing analysis of the newly identified MSPs. We will also outline Phase 2 of GCGPS using multiple post-correlation beam SPOTLIGHT systems targeting wider clusters as well as potential runaway MSPs providing evidence of strong gravitational interactions in dense stellar systems. |
