Abstract
Abstract We present new discoveries and results from long-term timing of 72 pulsars discovered in the Pulsar Arecibo L-band Feed Array (PALFA) survey, including precise determination of astrometric and spin parameters, and flux density and scatter broadening measurements at 1.4 GHz. Notable discoveries include two young pulsars (characteristic ages ∼30 kyr) with no apparent supernova remnant associations, three mode-changing, 12 nulling and two intermittent pulsars. We detected eight glitches in five pulsars. Among them is PSR J1939+2609, an apparently old pulsar (characteristic age ∼1 Gy), and PSR J1954+2529, which likely belongs to a newly emerging class of binary pulsars. The latter is the only pulsar among the 72 that is clearly not isolated: a nonrecycled neutron star with a 931 ms spin period in an eccentric (e = 0.114) wide (P b = 82.7 days) orbit with a companion of undetermined nature having a minimum mass of ∼0.6 M ⊙. Since operations at Arecibo ceased in 2020 August, we give a final tally of PALFA sky coverage, and compare its 207 pulsar discoveries to the known population. On average, they are 50% more distant than other Galactic plane radio pulsars; PALFA millisecond pulsars (MSPs) have twice the dispersion measure per unit spin period than the known population of MSP in the plane. The four intermittent pulsars discovered by PALFA more than double the population of such objects, which should help to improve our understanding of pulsar magnetosphere physics. The statistics for these, rotating radio transients, and nulling pulsars suggest that there are many more of these objects in the Galaxy than was previously thought.
Highlights
The observed population of radio pulsars currently numbers over 30001
While discovering millisecond pulsars (MSP) or partially recycled objects is important for fundamental physics experiments and neutronstar mass measurements (e.g., Arzoumanian et al 2018; Antoniadis et al 2013; Martinez et al 2015; Archibald et al 2018; Fonseca et al 2021) and studies of binary evolution, expanding the known population of normal pulsars is essential for understanding the neutron star population in terms of birth rates, magnetic fields, spatial distribution, and similar statistics
We present the results of several years of follow-up timing observations of an additional 72 longperiod (> 100 ms) pulsars found by the PALFA survey
Summary
The observed population of radio pulsars currently numbers over 30001. Approximately 500 of them have periods less than 100 ms, 80% of which are millisecond pulsars (MSPs) with periods . 30 ms, whereas the other. Thanks to Arecibo’s large collecting area and the high time and frequency resolution of PALFA data, the survey was prolific in discovering highly dispersed MSPs (Champion et al 2008; Deneva et al 2012; Crawford et al 2012; Allen et al.2013; Scholz et al 2015; Knispel et al 2015; Stovall et al 2016; Parent et al 2019) It was among the best surveys for finding compact binaries (Pol et al.2021) and/or highly accelerated systems, as evidenced by the discovery of three compact double neutron star systems (DNSs): PSR J1906+0746, the youngest DNS known (Lorimer et al 2006a; van Leeuwen et al 2015); PSR J1913+1102, a member of a new population of merging DNSs with large mass asymmetries (Lazarus et al 2016; Ferdman et al 2020) and PSR J1946+2052, the most compact DNS known in the Galaxy (Stovall et al 2018).
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