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1. Modeling the Future of Gaia Neutron Star–Main-sequence Binaries: From Eccentric Orbits to Millisecond Pulsar–White Dwarfs

   https://doi.org/10.3847/1538-4357/ae48f5  

   Chattopadhyay, Debatri; Rocha, Kyle A; Gossage, Seth; Kalogera, Vicky; El-Badry, Kareem; Tchekhovskoy, Alexander (March 2026, The Astrophysical Journal)

   Abstract We useMESAto model the future evolution of the 21 Gaia neutron star (NS)–main-sequence binaries (orbital periodP_orb ∼ 200–1000 days, eccentricitye ≳ 0.2) under two prescriptions: eccentric mass-transfer and enforced efficient circularization before the initiation of mass-transfer. All systems terminate as NS–white dwarfs (WDs), albeit different mass-transfer modes yield sharply divergent properties. Under eccentric mass-transfer, binaries are driven to higher eccentricities (finale ≳ 0.6 mostly) andP_orb ∼ 1000–4000 days. Mass-transfer episodes in eccentric orbits are brief (≲10⁶yr), transfer only a few ×10⁻²M_⊙, and produce only mildly recycled pulsars (spin-periodP_spin ∼ 100 ms) with low-mass helium WDs. Artificially circularized mass-transfer produces shorter final orbital periods ofP_orb ∼ 200–2000 days and allows mass-transfer to occur for ∼10⁷yr, so that the NSs accrete ∼0.1M_⊙, yielding fully recycled millisecond pulsars (MSPs) withP_spin ∼ few–30 ms, including nine systems with carbon–oxygen WDs. Enabling super-Eddington accretion up to 100× the canonical limit makes even eccentric channels efficiently produce MSPs. Incorporating an adaptive, field-dependent magnetic-field-decay timescale, our models reproduce the observed Gyr-long radio lifetimes of MSPs. Independent of the mass-transfer treatment, the descendants of these Gaia systems do not resemble the bulk of the known Galactic MSP–WD binaries, which are nearly circular withP_orb ≲ 100 days. The observed MSP–WDs are likely produced by systems with more massive companions that undergo unstable mass-transfer and NS in a common-envelope phase—an evolutionary channel that is not relevant for the Gaia binaries. 

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2. The Green Bank Northern Celestial Cap Pulsar Survey. VI. Discovery and Timing of PSR J1759+5036: A Double Neutron Star Binary Pulsar

   https://doi.org/10.3847/1538-4357/ac142b  

   Agazie, G. Y.; Mingyar, M. G.; McLaughlin, M. A.; Swiggum, J. K.; Kaplan, D. L.; Blumer, H.; Chawla, P.; DeCesar, M.; Demorest, P. B.; Fiore, W.; et al (November 2021, The Astrophysical Journal)

   Abstract The Green Bank North Celestial Cap survey is a 350 MHz all-sky survey for pulsars and fast radio transients using the Robert C. Byrd Green Bank Telescope. To date, the survey has discovered over 190 pulsars, including 33 millisecond pulsars and 24 rotating radio transients. Several exotic pulsars have been discovered in the survey, including PSR J1759+5036, a binary pulsar with a 176 ms spin period in an orbit with a period of 2.04 days, an eccentricity of 0.3, and a projected semi-major axis of 6.8 light seconds. Using seven years of timing data, we are able to measure one post–Keplerian parameter, advance of periastron, which has allowed us to constrain the total system mass to 2.62 ± 0.03 M ⊙ . This constraint, along with the spin period and orbital parameters, suggests that this is a double neutron star system, although we cannot entirely rule out a pulsar-white dwarf binary. This pulsar is only detectable in roughly 45% of observations, most likely due to scintillation. However, additional observations are required to determine whether there may be other contributing effects. 

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3. Study of 72 Pulsars Discovered in the PALFA Survey: Timing Analysis, Glitch Activity, Emission Variability, and a Pulsar in an Eccentric Binary

   https://doi.org/10.3847/1538-4357/ac375d  

   Parent, E.; Sewalls, H.; Freire, P. C.; Matheny, T.; Lyne, A. G.; Perera, B. B.; Cardoso, F.; McLaughlin, M. A.; Allen, B.; Brazier, A.; et al (January 2022, The Astrophysical Journal)

   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. 

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4. Discovery and Timing of Millisecond Pulsars with the Arecibo 327 MHz Drift-scan Survey

   https://doi.org/10.3847/1538-4357/acf99d  

   Lewis, Evan F.; Olszanski, Timothy E.; Deneva, Julia S.; Freire, Paulo C.; McLaughlin, Maura A.; Stovall, Kevin; Bagchi, Manjari; Martinez, Jose G.; Perera, Benetge B. (October 2023, The Astrophysical Journal)

   Abstract We present the discovery and timing solutions of four millisecond pulsars (MSPs) discovered in the Arecibo 327 MHz Drift-Scan Pulsar Survey. Three of these pulsars are in binary systems, consisting of a redback (PSR J2055+1545), a black widow (PSR J1630+3550), and a neutron star–white dwarf binary (PSR J2116+1345). The fourth MSP, PSR J2212+2450, is isolated. We present the multiyear timing solutions as well as polarization properties across a range of radio frequencies for each pulsar. We perform a multiwavelength search for emission from these systems and find an optical counterpart for PSR J2055+1545 in Gaia DR3, as well as a gamma-ray counterpart for PSR J2116+1345 with the Fermi-LAT telescope. Despite the close colocation of PSR J2055+1545 with a Fermi source, we are unable to detect gamma-ray pulsations, likely due to the large orbital variability of the system. This work presents the first two binaries found by this survey with orbital periods shorter than a day; we expect to find more in the 40% of the survey data that have yet to be searched. 

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5. A 350 MHz Green Bank Telescope Survey of Unassociated Fermi LAT Sources: Discovery and Timing of 10 Millisecond Pulsars

   https://doi.org/10.3847/1538-4357/ad2994  

   Bangale, P; Bhattacharyya, B; Camilo, F; Clark, C J; Cognard, I; DeCesar, M E; Ferrara, E C; Gentile, P; Guillemot, L; Hessels, J_W T; et al (May 2024, The Astrophysical Journal)

   Abstract We have searched for radio pulsations toward 49 Fermi Large Area Telescope (LAT) 1FGL Catalogγ-ray sources using the Green Bank Telescope at 350 MHz. We detected 18 millisecond pulsars (MSPs) in blind searches of the data; 10 of these were discoveries unique to our survey. 16 are binaries, with eight having short orbital periodsP_B< 1 day. No radio pulsations from young pulsars were detected, although three targets are coincident with apparently radio-quietγ-ray pulsars discovered in LAT data. Here, we give an overview of the survey and present radio andγ-ray timing results for the 10 MSPs discovered. These include the only isolated MSP discovered in our survey and six short-P_Bbinary MSPs. Of these, three have very-low-mass companions (M_c≪ 0.1M_⊙) and hence belong to the class of black widow pulsars. Two have more massive, nondegenerate companions with extensive radio eclipses and orbitally modulated X-ray emission consistent with the redback class. Significantγ-ray pulsations have been detected from nine of the discoveries. This survey and similar efforts suggest that the majority of Galacticγ-ray sources at high Galactic latitudes are either MSPs or relatively nearby nonrecycled pulsars, with the latter having on average a much smaller radio/γ-ray beaming ratio as compared to MSPs. It also confirms that past surveys suffered from an observational bias against finding short-P_BMSP systems. 

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