Follow-up of 27 radio-quiet gamma-ray pulsars at 110-190 MHz using the international LOFAR station FR606

Abstract

The Fermi Large Area Telescope has detected over 260 gamma-ray pulsars. About one quarter of these are labeled as radio-quiet. In the population of nonrecycled gamma-ray pulsars, the fraction of radio-quiet pulsars is higher, about one half. Most radio observations of gamma-ray pulsars have been performed at frequencies between 300 MHz and 2 GHz. However, pulsar radio fluxes increase rapidly with decreasing frequency, and their radio beams often broaden at low frequencies. As a consequence, some of these pulsars might be detectable at low radio frequencies even when no radio flux is detected above 300 MHz. Our aim is to test this hypothesis with low-frequency radio observations. We have observed 27 Fermi-discovered gamma-ray pulsars with the international LOw Frequency ARray (LOFAR) station FR606 in single-station mode. We used the LOFAR high band antenna (HBA) band (110-190 MHz). On average, we use 9 h of observation per target after the removal of affected datasets, resulting in a sensitivity for pulse-averaged flux on the order of 1-10 mJy. We do not detect radio pulsations from any of the 27 sources, and we establish stringent upper limits on their low-frequency radio fluxes. These nondetections are compatible with the upper limits derived from radio observations at other frequencies. We also determine the pulsars' geometry from the gamma-ray profiles to see for which pulsars the low-frequency radio beam is expected to cross Earth. This set of observations provides the most constraining upper limits on the flux density at 150 MHz for 27 radio-quiet gamma-ray pulsars. In spite of the beam-widening expected at low radio frequencies, most of our nondetections can be explained by an unfavorable viewing geometry; for the remaining observations, especially those of pulsars detected at higher frequencies, the nondetection is compatible with insufficient sensitivity.

17 pages, 3 figures, 1 appendix. Accepted by A&A

References in corpus (15)

• TEMPO2, a new pulsar timing package. I: Overview
• A New Electron Density Model for Estimation of Pulsar and FRB Distances
• Precise Gamma-Ray Timing and Radio Observations of 17 Fermi Gamma-Ray Pulsars
• Pulsar braking and the P-Pdot diagram
• Population synthesis of radio and gamma-ray millisecond pulsars from the Galactic disk
• Constraints on the Emission Geometries and Spin Evolution of Gamma-ray Millisecond Pulsars
• The Einstein@Home Gamma-ray Pulsar Survey. I. Search Methods, Sensitivity and Discovery of New Young Gamma-ray Pulsars
• Light-curve modelling constraints on the obliquities and aspect angles of the young Fermi pulsars
• PSR J1838-0537: Discovery of a young, energetic gamma-ray pulsar
• First detection of frequency-dependent, time-variable dispersion measures
• A deep campaign to characterize the synchronous radio/X-ray mode switching of PSR B0943+10
• On the usefulness of existing Solar-wind models for pulsar timing corrections
• A census of the pulsar population observed with the international LOFAR station FR606 at low frequencies (25-80~MHz)
• Simultaneous radio and X-ray observations of PSR B0611+22
• Deep searches for decameter wavelength pulsed emission from radio-quiet gamma-ray pulsars

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• Observing Jupiter's radio emissions using multiple LOFAR stations: a first case study of the Io-decametric emission using the Irish IE613, French FR606 and German DE604 stations
• XMM-Newton observations of PSR J0554+3107: pulsing thermal emission from a cooling high-mass neutron star