The LOFAR Tied-Array All-Sky Survey (LOTAAS): Characterization of 20 pulsar discoveries and their single-pulse behavior

TL;DR

This paper presents the discovery and detailed characterization of 20 pulsars from the LOFAR Tied-Array All-Sky Survey, including their timing, spectral, and single-pulse properties, revealing diverse behaviors and some unique slow-spinning pulsars.

Contribution

The study provides the first comprehensive timing and spectral analysis of 20 newly discovered pulsars from LOFAR, highlighting their diverse properties and behaviors.

Findings

Several pulsars are among the slowest known with P > 2 s.

Most pulsars have steep spectra with spectral indices between -4 and -1.

Large single-pulse variability observed, with some pulsars undetectable over 15% of the time.

Abstract

We are using the LOw-Frequency ARray (LOFAR) to perform the LOFAR Tied-Array All-Sky (LOTAAS) survey for pulsars and fast transients. Here we present the astrometric and rotational parameters of 20 pulsars discovered as part of LOTAAS. These pulsars have regularly been observed with LOFAR at 149 MHz and the Lovell telescope at 1532 MHz, supplemented by some observations with the Lovell telescope at 334 MHz and the Nancay Radio Telescope at 1484 MHz. Timing models are calculated for the 20 pulsars, some of which are among the slowest-spinning pulsars known. PSR J1236-0159 rotates with a period P ~ 3.6 s, while 5 additional pulsars show P > 2 s. Also, the spin-down rates Pdot are, on average, low, with PSR J0815+4611 showing Pdot ~ 4E-18. Some of the pulse profiles, generically single-peaked, present complex shapes evolving with frequency. Multi-frequency flux measurements show that these pulsars have generically relatively steep spectra but exceptions are present, with values ranging between ~ -4 and -1. Among the pulsar sample, a large fraction shows large single-pulse variability, with 4 pulsars being undetectable more than 15% of the time and one tentatively classified as a Rotating Radio Transient. Two single-peaked pulsars show drifting sub-pulses.