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Eight Millisecond Pulsars Discovered in the Arecibo PALFA Survey The University of Manchester Research Eight Millisecond Pulsars Discovered in the Arecibo PALFA Survey DOI: 10.3847/1538-4357/ab4f85 Document Version Final published version Link to publication record in Manchester Research Explorer Citation for published version (APA): Lyne, A., Stappers, B., & et al. (2020). Eight Millisecond Pulsars Discovered in the Arecibo PALFA Survey. The Astrophysical Journal, 886(2), 148. [148]. https://doi.org/10.3847/1538-4357/ab4f85 Published in: The Astrophysical Journal Citing this paper Please note that where the full-text provided on Manchester Research Explorer is the Author Accepted Manuscript or Proof version this may differ from the final Published version. If citing, it is advised that you check and use the publisher's definitive version. General rights Copyright and moral rights for the publications made accessible in the Research Explorer are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Takedown policy If you believe that this document breaches copyright please refer to the University of Manchester’s Takedown Procedures [http://man.ac.uk/04Y6Bo] or contact [email protected] providing relevant details, so we can investigate your claim. Download date:24. Sep. 2021 The Astrophysical Journal, 886:148 (17pp), 2019 December 1 https://doi.org/10.3847/1538-4357/ab4f85 © 2019. The American Astronomical Society. All rights reserved. Eight Millisecond Pulsars Discovered in the Arecibo PALFA Survey E. Parent1 , V. M. Kaspi1 , S. M. Ransom2 , P. C. C. Freire3 , A. Brazier4, F. Camilo5 , S. Chatterjee4 , J. M. Cordes4 , F. Crawford6 , J. S. Deneva7 , R. D. Ferdman8 , J. W. T. Hessels9,10 , J. van Leeuwen9,10, A. G. Lyne11, E. C. Madsen1, M. A. McLaughlin12,13 , C. Patel1, P. Scholz14 , I. H. Stairs15 , B. W. Stappers11, and W. W. Zhu16 1 Dept. of Physics and McGill Space Institute, McGill University, Montreal, QC H3A 2T8, Canada 2 NRAO, 520 Edgemont Road, Charlottesville, VA 22903, USA 3 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, Bonn D-53121, Germany 4 Cornell Center for Astrophysics and Planetary Science, Ithaca, NY 14853, USA 5 South African Radio Astronomy Observatory, Observatory, 7925, South Africa 6 Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003, USA 7 George Mason University, resident at the Naval Research Laboratory, Washington, DC 20375, USA 8 School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK 9 ASTRON, the Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands 10 Anton Pannekoek Institute for Astronomy, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands 11 JBCA, School of Physics & Astronomy, University of Manchester, Manchester, M13 9PL, UK 12 Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26501, USA 13 Center for Gravitational Waves and Cosmology, West Virginia University, Chestnut Ridge Research Building, Morgantown, WV 26505, USA 14 Dominion Radio Astrophysical Observatory, Herzberg Astronomy & Astrophysics Research Centre, National Reseach Council Canada, P.O. Box 248, Penticton, V2A 6J9, Canada 15 Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 Canada 16 CAS Key Laboratory of FAST, NAOC, Chinese Academy of Sciences, Beijing 100101, Peopleʼs Republic of China Received 2019 August 13; revised 2019 October 15; accepted 2019 October 16; published 2019 December 3 Abstract We report on eight millisecond pulsars (MSPs) in binary systems discovered with the Arecibo L-Band Feed Array (PALFA) pulsar survey. Phase-coherent timing solutions derived from 2.5–5 yr of observations carried out at the Arecibo and Jodrell Bank observatories are provided. PSR J1921+1929 is a 2.65 ms pulsar in a 39.6 day orbit for which we detect γ-ray pulsations in archival Fermi data. PSR J1928+1245 is a very low-mass-function system with an orbital period of 3.3 hr that belongs to the non-eclipsing black widow population. We also present PSR J1932+1756, the longest-orbital-period (41.5 days) intermediate-mass binary pulsar known to date. In light of the numerous discoveries of binary MSPs over the past years, we characterize the Galactic distribution of known MSP binaries in terms of binary class. Our results support and strengthen previous claims that the scatter in the Galactic scale height distribution correlates inversely with the binary mass function. We provide evidence of observational biases against detecting the most recycled pulsars near the Galactic plane, which overestimates the scale height of lighter systems. A possible bimodality in the mass function of MSPs with massive white dwarfs is also reported. Unified Astronomy Thesaurus concepts: Millisecond pulsars (1062); Pulsar timing method (1305); Radio pulsars (1353); Galactic radio sources (571); Binary pulsars (153); Pulsars (1306); Neutron stars (1108); Radio astronomy (1338); Surveys (1671) 1. Introduction discovered, representing ∼10% of the total known pulsar 17 ( ) ( ) population, and roughly half of those are found in globular Millisecond pulsars MSPs are short-period P 100 ms 18 neutron stars that differ from normal pulsars primarily clusters. The extraordinarily stable rotation of most MSPs allows us because of their remarkably small spin-down rates to use them as celestial clocks in a variety of applications. One (P˙ 10-17) and their different evolutionary histories. Only notable example is their use as probes of binary motion, ∼1% of all normal pulsars are in binary systems, while we enabling precise neutron-star mass measurements and tests of observe orbiting companions (predominantly white dwarfs) relativistic gravitational theories. Such studies led to the first in around 80% of MSPs. Their properties are consistent with confirmation of the existence of gravitational radiation (Taylor them being old pulsars that have been spun up by the et al. 1979) predicted by the theory of general relativity. accretion of material from a companion (Alpar et al. 1982; The continued discoveries of MSPs is also motivated by the Radhakrishnan & Srinivasan 1982; Bhattacharya & van den effort to detect nanohertz gravitational waves (GWs) emitted by a Heuvel 1991). For this reason, they are often referred to as cosmological population of supermassive black hole binaries via “recycled pulsars.” While the generally accepted definition a “pulsar timing array” (PTA; Hellings & Downs 1983;Foster& of MSPs is pulsars having P 30 ms, we shall apply Backer 1990; Jaffe & Backer 2003; Hobbs et al. 2010).This throughout this work the broader definition proposed in effort relies on the stability of the MSPs forming the array and the Manchester (2017): pulsars with P < 100 ms whose P˙ is −17 smaller than 10 . This allows us to include many pulsars 17 ( http://www.atnf.csiro.au/research/pulsar/psrcat/ (Manchester et al. 2005), having had short-lived recycling phases e.g., PSR J1753 version 1.60 of the ATNF Pulsar Catalogue. − ) ( 18 2240 while excluding young pulsars e.g., the Crab pulsar According to the Pulsars in Globular Clusters Catalogue available athttp:// B0531+21). To date, more than 300 MSPs have been www.naic.edu/~pfreire/GCpsr.html. 1 The Astrophysical Journal, 886:148 (17pp), 2019 December 1 Parent et al. expected disturbances in the pulse times of arrival (TOAs) by University and searches for pulsars in the Fourier domain. It passing GWs. Correlations in those disturbances as a function of also searches in the time domain, for pulsars with a fast-folding angular separation are then inspected to identify potential signals algorithm (Parent et al. 2018), and has a single-pulse pipeline in the form of a stochastic background. Improving PTA (Patel et al. 2018) that searches for rotating radio transients and sensitivities is most effectively achieved by increasing the fast radio bursts. For a more detailed description of the survey, number of MSPs with high timing precision (Siemens et al. see Lazarus et al. (2015). 2013). The GW signals detectable by PTAs are in the nanohertz frequency range, many orders of magnitude below the band 2.1. Discovery where laser-interferometer systems, such as aLIGO (Abbott et al. 2009), are sensitive. PTA efforts are therefore complementary to The eight MSPs presented in this work were all discovered interferometric ground-based detectors and can ultimately reveal in the 268 sec inner-Galaxy pointings between 2014 June and information about the kinematics, morphology, content, and 2016 November. Four of them (PSRs J1921+1929, J1930 feedback mechanisms of galaxies. +2441, J1937+1658, and J2010+3051) were first identified by The Arecibo L-Band Feed Array (PALFA) pulsar survey the “Quicklook” pipeline, while PSRs J1906+0454, J1913 uses the 7-beam Arecibo L-band Feed Array (ALFA) on the +0618, J1928+1245, and J1932+1756 were detected by the Arecibo Observatory (AO) William E. Gordon 305 m telescope full-resolution pipeline only. Additional observations were then in Puerto Rico. It has been surveying low-latitude regions of carried out to confirm the new sources. the Galactic plane at 1.4 GHz since 2004 (Cordes et al. 2006; Lazarus et al. 2015). The great sensitivity of PALFA and its 2.2. Timing Observations observational parameters (see Section 2) are excellent for finding faint, highly dispersed pulsars. To date, the survey has To determine the rotational, astrometric, and binary para- discovered 192 pulsars,19 including three double neutron star meters of the systems, follow-up observations for all eight (DNS) systems (Lorimer et al. 2006; van Leeuwen et al. 2015; pulsars were conducted at AO using the dual-linear-feed L- Lazarus et al. 2016; Stovall et al. 2018) and 40 highly recycled wide receiver. In order to obtain timing solutions rapidly when MSPs20 (e.g., Champion et al. 2008; Crawford et al. 2012; pulsars were added to our timing program, three pulsars (PSRs Deneva et al.
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