The LOFAR Tied-Array All-Sky Survey: Timing of 35 radio pulsars and an overview of the properties of the LOFAR pulsar discoveries

TL;DR

LOTAAS, a low-frequency radio pulsar survey, discovered 76 pulsars, including the slowest-spinning known pulsar, and provided detailed timing and property analyses revealing unique spectral and temporal characteristics.

Contribution

This paper completes the timing analysis of 35 pulsars from LOTAAS and offers an overview of the properties of all 76 pulsars discovered, highlighting their unique spectral and temporal features.

Findings

LOTAAS discovered 76 new pulsars, including the slowest-spinning known pulsar.

Most pulsars show no pulse broadening, with some exhibiting profile variations.

Discovered pulsars have steeper spectra, longer periods, and lower spin-down rates compared to known pulsars.

Abstract

The LOFAR Tied-Array All-Sky Survey (LOTAAS) is the most sensitive untargeted radio pulsar survey performed at low radio frequencies (119--151\,MHz) to date and has discovered 76 new radio pulsars, among which the 23.5-s pulsar J0250+5854, up until recently the slowest-spinning radio pulsar known. Here, we report on the timing solutions of 35 pulsars discovered by LOTAAS, which include a nulling pulsar and a mildly recycled pulsar, and thereby complete the full timing analysis of the LOTAAS pulsar discoveries. We give an overview of the findings from the full LOTAAS sample of 76 pulsars, discussing their pulse profiles, radio spectra and timing parameters. We found that the pulse profiles of some of the pulsars show profile variations in time or frequency and while some pulsars show signs of scattering, a large majority display no pulse broadening. The LOTAAS discoveries have on average steeper radio spectra and have longer spin periods ($1.4\times$) as well as lower spin-down rates ($3.1\times$) compared to the known pulsar population. We discuss the cause of these differences, and attribute them to a combination of selection effects of the LOTAAS survey as well as previous pulsar surveys, though can not rule out that older pulsars tend to have steeper radio spectra.