S. M. Ransom
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View article: Testing Gravity with Binary Pulsars in the SKA Era
Testing Gravity with Binary Pulsars in the SKA Era Open
Binary (and trinary) radio pulsars are natural laboratories in space for understanding gravity in the strong field regime, with many unique and precise tests carried out so far, including the most precise tests of the strong equivalence pr…
View article: Galactic Centre Pulsars with the SKAO
Galactic Centre Pulsars with the SKAO Open
The detection of a pulsar closely orbiting our Galaxy’s supermassive black hole - Sagittarius A* - is one of the ultimate prizes in pulsar astrophysics. The relativistic effects expected in such a system could far exceed those currently ob…
View article: Einstein@Home Searches for Gamma-Ray Pulsars in the Inner Galaxy
Einstein@Home Searches for Gamma-Ray Pulsars in the Inner Galaxy Open
The Fermi Large Area Telescope (LAT) has revealed a mysterious extended excess of GeV gamma-ray emission around the Galactic Center (GC), which can potentially be explained by unresolved emission from a population of pulsars, particularly …
View article: Circumventing the Politics of Water to Achieve Equitable and Sustainable Access in Australia
Circumventing the Politics of Water to Achieve Equitable and Sustainable Access in Australia Open
As the world approaches the 2030 Sustainable Development Goals (SDGs) deadline, ensuring equitable access to safe and sustainable drinking water remains a pressing challenge. This paper, informed by a roundtable discussion involving a dive…
View article: The NANOGrav 15-Year Data Set: Improved Timing Precision With VLBI Astrometric Priors
The NANOGrav 15-Year Data Set: Improved Timing Precision With VLBI Astrometric Priors Open
Accurate pulsar astrometric estimates play an essential role in almost all high-precision pulsar timing experiments. Traditional pulsar timing techniques refine these estimates by including them as free parameters when fitting a model to o…
View article: CHIME/Fast Radio Burst/Pulsar Discovery of a Nearby Long-period Radio Transient with a Timing Glitch
CHIME/Fast Radio Burst/Pulsar Discovery of a Nearby Long-period Radio Transient with a Timing Glitch Open
We present the discovery of a 421 s long period transient using the CHIME telescope, CHIME J0630+25. The source is localized to R.A. = 06:30:38.4 decl. = 25:26:23 using voltage data acquired with the CHIME baseband system. A timing…
View article: PrestoZL: A GPU-accelerated High-throughput Jerk Search Toolkit for Binary Pulsars
PrestoZL: A GPU-accelerated High-throughput Jerk Search Toolkit for Binary Pulsars Open
The Fourier domain jerk search algorithm, an integral component of the PRESTO software suite, has emerged as a key tool for detecting binary pulsars. However, it is a CPU-based jerk search and is a very computationally expensive process, p…
View article: Rapid construction of joint pulsar timing array data sets: the Lite method
Rapid construction of joint pulsar timing array data sets: the Lite method Open
The International Pulsar Timing Array (IPTA)’s second data release (IPTA DR2) combines decades of observations of 65 millisecond pulsars from 7 radio telescopes. IPTA data sets should be the most sensitive data sets to nanohertz gravitatio…
View article: CHIME All-sky Multiday Pulsar Stacking Search (CHAMPSS): System Overview and First Discoveries
CHIME All-sky Multiday Pulsar Stacking Search (CHAMPSS): System Overview and First Discoveries Open
We describe the Canadian Hydrogen Intensity Mapping Experiment (CHIME) All-sky Multiday Pulsar Stacking Search (CHAMPSS) project. This novel radio pulsar survey revisits the full northern sky daily, offering unprecedented opportunity to de…
View article: FRB 20250316A: A Brilliant and Nearby One-off Fast Radio Burst Localized to 13 pc Precision
FRB 20250316A: A Brilliant and Nearby One-off Fast Radio Burst Localized to 13 pc Precision Open
Precise localizations of a small number of repeating fast radio bursts (FRBs) using very long baseline interferometry (VLBI) have enabled multiwavelength follow-up observations revealing diverse local environments. However, the 2%–3% of FR…
View article: The FAST Globular Cluster Pulsar Survey (GC FANS)
The FAST Globular Cluster Pulsar Survey (GC FANS) Open
By 2025 January, 60 pulsars were discovered by the Five-hundred-meter Aperture Spherical radio Telescope globular cluster (GC) pulsar survey (GC FANS), with spin periods spanning 1.98–3960.72 ms. Of these, 55 are millisecond pulsars (MSPs;…
View article: The NANOGrav 15-year Data Set: Search for Gravitational Scattering of Pulsars by Free-Floating Objects in Interstellar Space
The NANOGrav 15-year Data Set: Search for Gravitational Scattering of Pulsars by Free-Floating Objects in Interstellar Space Open
Free-floating objects (FFOs) in interstellar space$-$rogue planets, brown dwarfs, and large asteroids that are not gravitationally bound to any star$-$are expected to be ubiquitous throughout the Milky Way. Recent microlensing surveys have…
View article: Globular Clusters GMRT Pulsar Search (GCGPS). I. Survey Description, Discovery and Timing of the First Pulsar in NGC6093 (M80)
Globular Clusters GMRT Pulsar Search (GCGPS). I. Survey Description, Discovery and Timing of the First Pulsar in NGC6093 (M80) Open
This paper describes the new Globular Clusters GMRT Pulsar Search survey. This survey aims to find millisecond pulsars (MSPs) in the globular clusters (GCs) of the Milky Way using the upgraded Giant Metrewave Radio Telescope (uGMRT). Using…
View article: CHIME/Fast Radio Burst Discovery of an Unusual Circularly Polarized Long-period Radio Transient with an Accelerating Spin Period
CHIME/Fast Radio Burst Discovery of an Unusual Circularly Polarized Long-period Radio Transient with an Accelerating Spin Period Open
We report the discovery of CHIME J1634+44, a long-period radio transient (LPT) unique for two aspects: it is the first known LPT to emit fully circularly polarized radio bursts, and it is the first LPT with a significant spin-up. Given tha…
View article: FRB 20250316A: A Brilliant and Nearby One-Off Fast Radio Burst Localized to 13 parsec Precision
FRB 20250316A: A Brilliant and Nearby One-Off Fast Radio Burst Localized to 13 parsec Precision Open
Precise localizations of a small number of repeating fast radio bursts (FRBs) using very long baseline interferometry (VLBI) have enabled multiwavelength follow-up observations revealing diverse local environments. However, the 2--3\% of F…
View article: The NANOGrav 15 yr Data Set: Search for Gravitational-wave Memory
The NANOGrav 15 yr Data Set: Search for Gravitational-wave Memory Open
We present the results of a search for nonlinear gravitational-wave (GW) memory in the NANOGrav 15 yr data set. We find no significant evidence for memory signals in the data set, with a maximum Bayes factor of 3.1 in favor of a model incl…
View article: Pulscan: Binary Pulsar Detection Using Unmatched Filters on NVIDIA GPUs
Pulscan: Binary Pulsar Detection Using Unmatched Filters on NVIDIA GPUs Open
The Fourier domain acceleration search (FDAS) and Fourier domain jerk search (FDJS) are proven matched-filtering techniques for detecting binary pulsar signatures in time-domain radio astronomy data sets. Next-generation radio telescopes s…
View article: The NANOGrav 12.5 yr Data Set: Probing Interstellar Turbulence and Precision Pulsar Timing with PSR J1903+0327
The NANOGrav 12.5 yr Data Set: Probing Interstellar Turbulence and Precision Pulsar Timing with PSR J1903+0327 Open
Free electrons in the interstellar medium refract and diffract radio waves along multiple paths, resulting in angular and temporal broadening of radio pulses that limits pulsar timing precision. We determine multifrequency, multiepoch scat…
View article: The NANOGrav 12.5 yr Data Set: Probing Interstellar Turbulence and Precision Pulsar Timing with PSR J1903+0327
The NANOGrav 12.5 yr Data Set: Probing Interstellar Turbulence and Precision Pulsar Timing with PSR J1903+0327 Open
Free electrons in the interstellar medium refract and diffract radio waves along multiple paths, resulting in angular and temporal broadening of radio pulses that limits pulsar timing precision. We determine multifrequency, multiepoch scat…
View article: The NANOGrav 15-Year Data Set: A Case Study for Simplified Dispersion Measure Modeling for PSR J1455-3330 and the Impact on Gravitational Wave Sensitivity
The NANOGrav 15-Year Data Set: A Case Study for Simplified Dispersion Measure Modeling for PSR J1455-3330 and the Impact on Gravitational Wave Sensitivity Open
Evidence for a low-frequency gravitational-wave background using pulsar timing arrays has generated recent interest into its underlying contributing sources. However, multiple investigations have seen that the significance of the evidence …
View article: The NANOGrav 15 yr Data Set: Harmonic Analysis of the Pulsar Angular Correlations
The NANOGrav 15 yr Data Set: Harmonic Analysis of the Pulsar Angular Correlations Open
Pulsar timing array observations have found evidence for an isotropic gravitational-wave background with the Hellings–Downs angular correlations between pulsar pairs. This interpretation hinges on the measured shape of the angular correlat…
View article: Discovery and Timing of Four <i>γ</i>-Ray Millisecond Pulsars
Discovery and Timing of Four <i>γ</i>-Ray Millisecond Pulsars Open
We discovered four millisecond pulsars (MSPs) in searches of 80 γ -ray sources conducted from 2015 to 2017 with the Murriyang radio telescope of the Parkes Observatory. We provide an overview of the survey and focus on the results of a fol…
View article: Pulse Profile Variability of PSR J1022+1001 in NANOGrav Data
Pulse Profile Variability of PSR J1022+1001 in NANOGrav Data Open
Pulse profile stability is a central assumption of standard pulsar timing methods. Thus, it is important for pulsar timing array experiments such as the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) to account for…
View article: An <i>S</i>-band Search for Highly Scattered Young Pulsars Toward Low Galactic Latitude Fermi Sources
An <i>S</i>-band Search for Highly Scattered Young Pulsars Toward Low Galactic Latitude Fermi Sources Open
We searched 20 unidentified Fermi sources at low Galactic latitudes for highly scattered young pulsars in the Northern sky. We performed ∼2 hr observations of each source with the Green Bank Telescope using the S band receiver, choosing so…
View article: The Anomalous Acceleration of PSR J2043+1711: Long-period Orbital Companion or Stellar Flyby?
The Anomalous Acceleration of PSR J2043+1711: Long-period Orbital Companion or Stellar Flyby? Open
Based on the rate of change of its orbital period, PSR J2043+1711 has a substantial peculiar acceleration of 3.5 ± 0.8 mm s –1 yr –1 , which deviates from the acceleration predicted by equilibrium Milky Way (MW) models at a 4 σ level. The …
View article: A Lower Mass Estimate for PSR J0348+0432 Based on CHIME/Pulsar Precision Timing
A Lower Mass Estimate for PSR J0348+0432 Based on CHIME/Pulsar Precision Timing Open
The binary pulsar J0348+0432 was previously shown to have a mass of approximately 2 M ⊙ , based on the combination of radial-velocity and model-dependent mass parameters derived from high-resolution optical spectroscopy of its white-dwarf …
View article: A 34 yr Timing Solution of the Redback Millisecond Pulsar Terzan 5A
A 34 yr Timing Solution of the Redback Millisecond Pulsar Terzan 5A Open
We present a 34 yr timing solution of the redback pulsar system Terzan 5A (Ter5A). Ter5A, also known as B1744−24A or J1748−2446A, has a 11.56 ms pulse period, a ~0.1 M ⊙ dwarf companion star, and an orbital period of 1.82 hr. Ter5A display…
View article: Probing Globular Cluster with MeerKAT and FAST: A Pulsar Polarization Census
Probing Globular Cluster with MeerKAT and FAST: A Pulsar Polarization Census Open
Only one globular cluster (GC), 47 Tuc, has been found to contain intracluster medium, with an electron density 100 times higher than that of the ISM in its vicinity. The characteristics of this intracluster medium are closely related to G…
View article: The NANOGrav 15-year Data Set: Search for Gravitational Wave Memory
The NANOGrav 15-year Data Set: Search for Gravitational Wave Memory Open
We present the results of a search for nonlinear gravitational wave memory in the NANOGrav 15-year data set. We find no significant evidence for memory signals in the dataset, with a maximum Bayes factor of 3.1 in favor of a model includin…