Searching for pulsars associated with polarised point sources using LOFAR: Initial discoveries from the TULIPP project

Abstract

Discovering radio pulsars, particularly millisecond pulsars (MSPs), is important for a range of astrophysical applications, such as testing theories of gravity or probing the magneto-ionic interstellar medium. We aim to discover pulsars that may have been missed in previous pulsar searches by leveraging known pulsar observables (primarily polarisation) in the sensitive, low-frequency radio images from the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS), and have commenced the Targeted search, using LoTSS images, for polarised pulsars (TULIPP) survey. For this survey, we identified linearly and circularly polarised point sources with flux densities brighter than 2 mJy in LoTSS images at a centre frequency of 144 MHz with a 48 MHz bandwidth. Over 40 known pulsars, half of which are MSPs, were detected as polarised sources in the LoTSS images and excluded from the survey. We have obtained beam-formed LOFAR observations of 30 candidates, which were searched for pulsations using coherent de-dispersion. Here, we present the results of the first year of the TULIPP survey. We discovered two pulsars, PSRs J1049+5822 and J1602+3901, with rotational periods of P=0.73 s and 3.7 ms, respectively. We also detected a further five known pulsars (two slowly-rotating pulsars and three MSPs) for which accurate sky positions were not available to allow a unique cross-match with LoTSS sources. This targeted survey presents a relatively efficient method by which pulsars, particularly MSPs, may be discovered using the flexible observing modes of sensitive radio telescopes such as the Square Kilometre Array and its pathfinders/precursors, particularly since wide-area all-sky surveys using coherent de-dispersion are currently computationally infeasible.

15 pages, 7 figures, 3 tables. Accepted for publication in A&A

References in corpus (56)

• Array Programming with NumPy
• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• TEMPO2, a new pulsar timing package. I: Overview
• A New Electron Density Model for Estimation of Pulsar and FRB Distances
• PSRCHIVE and PSRFITS An Open Approach to Radio Pulsar Data Storage and Analysis
• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• Tempo2, a new pulsar timing package. II: The timing model and precision estimates
• The Parkes multibeam pulsar survey: VI. Discovery and timing of 142 pulsars and a Galactic population analysis
• The LOFAR Two-metre Sky Survey -- V. Second data release
• The Last of FIRST: The Final Catalog and Source Identifications
• Pulsar Nulling and Mode Changing
• The LOFAR Two Meter Sky Survey: Deep Fields, I -- Direction-dependent calibration and imaging
• The Green Bank Northern Celestial Cap Pulsar Survey - I: Survey Description, Data Analysis, and Initial Results
• The FAST Galactic Plane Pulsar Snapshot survey: I. Project design and pulsar discoveries
• Calibrating High-Precision Faraday Rotation Measurements for LOFAR and the Next Generation of Low-Frequency Radio Telescopes
• A radio spectral index map and catalogue at 147-1400 MHz covering 80 per cent of the sky
• Low-frequency Faraday rotation measures towards pulsars using LOFAR: probing the 3-D Galactic halo magnetic field
• A 1.4-GHz Arecibo Survey for Pulsars in Globular Clusters
• The LOFAR Tied-Array All-Sky Survey (LOTAAS): Survey overview and initial pulsar discoveries
• The SUrvey for Pulsars and Extragalactic Radio Bursts I: Survey Description and Overview
• The LOFAR Pilot Surveys for Pulsars and Fast Radio Transients
• Pulsar polarisation below 200 MHz: Average profiles and propagation effects
• Spin-Down of Radio Millisecond Pulsars at Genesis
• Eight new millisecond pulsars from the first MeerKAT globular cluster census
• LOFAR discovery of the fastest-spinning millisecond pulsar in the Galactic field
• The population of M dwarfs observed at low radio frequencies
• FAST Globular Cluster Pulsar Survey: Twenty-Four Pulsars Discovered in Fifteen Globular Clusters
• Scattering analysis of LOFAR pulsar observations
• Multi-frequency integrated profiles of pulsars
• The challenges of low-frequency radio polarimetry: lessons from the Murchison Widefield Array
• A circular polarisation survey for radio stars with the Australian SKA Pathfinder
• Cataloging the radio-sky with unsupervised machine learning: a new approach for the SKA era
• Constraints from Faraday rotation on the magnetic field structure in the Galactic halo
• Unveiling the rarest morphologies of the LOFAR Two-metre Sky Survey radio source population with self-organised maps
• An image-based search for pulsars among Fermi unassociated LAT sources
• Gaia pulsars and where to find them
• Direct radio discovery of a cold brown dwarf
• An in-depth investigation of 11 pulsars discovered by FAST
• Discovery of Millisecond Pulsars in the Globular Cluster Omega Centauri
• A polarization census of bright pulsars using the Ultra-Wideband Receiver on the Parkes radio telescope
• Faraday rotation measures of northern-hemisphere pulsars using CHIME/Pulsar
• The LOFAR Tied-Array All-Sky Survey: Timing of 21 pulsars including the first binary pulsar discovered with LOFAR
• Flux density variability of 286 radio pulsars from a decade of monitoring
• A Census of Southern Pulsars at 185 MHz
• A millisecond pulsar discovery in a survey of unidentified Fermi $\gamma$-ray sources with LOFAR
• The Tail of PSR J0002+6216 and the Supernova Remnant CTB 1
• Millisecond Pulsar Scintillation Studies with LOFAR: Initial Results
• Discovery and timing of three millisecond pulsars in radio and gamma-rays with the GMRT and Fermi-LAT
• Prospects for Discovering Pulsars in Future Continuum Surveys Using Variance Imaging
• Discovery of a steep-spectrum low-luminosity pulsar with the Murchison Widefield Array
• Radio Detection of PSR J1813-1749 in HESS J1813-178: The Most Scattered Pulsar Known
• LOFAR Deep Fields: Probing a broader population of polarized radio galaxies in ELAIS-N1
• Twenty Years of Searching for (and Finding) Globular Cluster Pulsars
• A supernova remnant association for the fast-moving pulsar PSR J0908-4913