Known Pulsars Identified in the GMRT 150 MHz All-Sky Survey

TL;DR

This study used the GMRT 150 MHz survey to identify radio emission from pulsars, revealing new detections, analyzing their properties, and comparing flux densities with other surveys, especially noting steep spectra in gamma-ray binaries.

Contribution

First comprehensive 150 MHz survey of well-localized pulsars, identifying 288 pulsars and analyzing their spectral properties and flux density discrepancies with LOFAR.

Findings

Detected 200 pulsars with high confidence and 88 at fainter levels.

Found many gamma-ray binary millisecond pulsars with steep spectral indices.

Identified a flux density scale discrepancy between GMRT and LOFAR samples.

Abstract

We have used the 150 MHz radio continuum survey (TGSS ADR) from the Giant Metrewave Radio Telescope (GMRT) to search for phase-averaged emission toward all well-localized radio pulsars north of -53deg Declination. We detect emission toward 200 pulsars with high confidence (>=5-sigma) and another 88 pulsars at fainter levels. We show that most of our identifications are likely from pulsars, except for a small number where the measured flux density is confused by an associated supernova or pulsar-wind nebula, or a globular cluster. We investigate the radio properties of the 150 MHz sample and we find an unusually high number of gamma-ray binary millisecond pulsars with very steep spectral indices. We also note a discrepancy in the measured flux densities between GMRT and LOFAR pulsar samples, suggesting that the flux density scale for the LOFAR pulsar sample may be in error by approximately a factor two. We carry out a separate search of 30 well-localized gamma-ray, radio-quiet pulsars in an effort to detect a widening of the radio beam into the line-of-sight at lower frequencies. No steep spectrum emission was detected either toward individual pulsars or in a weighted stack of all 30 images.