James W. McKee
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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: Echoes in Different Tempo: Long-Term Monitoring of Crab Echoes with CHIME
Echoes in Different Tempo: Long-Term Monitoring of Crab Echoes with CHIME Open
The Crab Pulsar is known to feature plasma lensing events known as echoes. These events show additional components in the pulse profile which are produced by signal that is deflected by ionized nebular material and are therefore delayed re…
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: 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: 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: 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: Searches for signatures of ultralight axion dark matter in polarimetry data of the European Pulsar Timing Array
Searches for signatures of ultralight axion dark matter in polarimetry data of the European Pulsar Timing Array Open
Ultralight axionlike particles (ALPs) can be a viable solution to the dark matter problem. The scalar field associated with ALPs, coupled to the electromagnetic field acts as an active birefringent medium, altering the polarization propert…
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…
View article: The NANOGrav 15 yr Data Set: Running of the Spectral Index
The NANOGrav 15 yr Data Set: Running of the Spectral Index Open
The NANOGrav 15 yr data provide compelling evidence for a stochastic gravitational-wave (GW) background at nanohertz frequencies. The simplest model-independent approach to characterizing the frequency spectrum of this signal consists of a…
View article: The NANOGrav 15 Yr Data Set: Removing Pulsars One by One from the Pulsar Timing Array
The NANOGrav 15 Yr Data Set: Removing Pulsars One by One from the Pulsar Timing Array Open
Evidence has emerged for a stochastic signal correlated among 67 pulsars within the 15 yr pulsar-timing data set compiled by the NANOGrav collaboration. Similar signals have been found in data from the European, Indian, Parkes, and Chinese…
View article: The NANOGrav 15 yr Data Set: Looking for Signs of Discreteness in the Gravitational-wave Background
The NANOGrav 15 yr Data Set: Looking for Signs of Discreteness in the Gravitational-wave Background Open
The cosmic merger history of supermassive black hole binaries (SMBHBs) is expected to produce a low-frequency gravitational wave background (GWB). Here we investigate how signs of the discrete nature of this GWB can manifest in pulsar timi…
View article: The impact on astrometry by solar-wind effect in pulsar timing
The impact on astrometry by solar-wind effect in pulsar timing Open
Astrometry of pulsars, particularly their distances, serves as a critical input for various astrophysical experiments using pulsars. Pulsar timing is a primary approach for determining a pulsar’s position, parallax, and distance. In this p…
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\,${\rm M_\odot}$, based on the combination of radial-velocity and model-dependent mass parameters derived from high-resolution optical spectroscopy of its …
View article: The NANOGrav 15 Yr Data Set: Removing Pulsars One by One from the Pulsar Timing Array
The NANOGrav 15 Yr Data Set: Removing Pulsars One by One from the Pulsar Timing Array Open
Evidence has emerged for a stochastic signal correlated among 67 pulsars within the 15-year pulsar-timing data set compiled by the NANOGrav collaboration. Similar signals have been found in data from the European, Indian, Parkes, and Chine…
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, expected from general relativity. This interpretation hinges on the measured shape of the ang…
View article: Galaxy Tomography with the Gravitational Wave Background from Supermassive Black Hole Binaries
Galaxy Tomography with the Gravitational Wave Background from Supermassive Black Hole Binaries Open
The detection of a stochastic gravitational wave background by pulsar timing arrays suggests the presence of a supermassive black hole binary population. Although the observed spectrum generally matches predictions for orbital evolution dr…
View article: The NANOGrav 15 yr Data Set: Chromatic Gaussian Process Noise Models for Six Pulsars
The NANOGrav 15 yr Data Set: Chromatic Gaussian Process Noise Models for Six Pulsars Open
Pulsar timing arrays (PTAs) are designed to detect low-frequency gravitational waves (GWs). GWs induce achromatic signals in PTA data, meaning that the timing delays do not depend on radio frequency. However, pulse arrival times are also a…
View article: The NANOGrav 15 yr Data Set: Running of the Spectral Index
The NANOGrav 15 yr Data Set: Running of the Spectral Index Open
The NANOGrav 15-year data provides compelling evidence for a stochastic gravitational-wave (GW) background at nanohertz frequencies. The simplest model-independent approach to characterizing the frequency spectrum of this signal consists i…
View article: Erratum: “The NANOGrav 15 yr Data Set: Search for Signals from New Physics” (2023, ApJL 951 L11)
Erratum: “The NANOGrav 15 yr Data Set: Search for Signals from New Physics” (2023, ApJL 951 L11) Open
Erratum: "The NANOGrav 15 yr Data Set: Search for Signals from New Physics" (2023, ApJL 951 L11), Adeela Afzal, Gabriella Agazie, Akash Anumarlapudi, Anne M. Archibald, Zaven Arzoumanian, Paul T. Baker, Bence Bécsy, Jose Juan Blanco-Pillad…
View article: Constraining the Selection-corrected Luminosity Function and Total Pulse Count for Radio Transients
Constraining the Selection-corrected Luminosity Function and Total Pulse Count for Radio Transients Open
Studying transient phenomena, such as individual pulses from pulsars, has garnered considerable attention in the era of astronomical big data. Of specific interest to this study are rotating radio transients (RRATs), nulling, and intermitt…
View article: The NANOGrav 15 yr data set: Posterior predictive checks for gravitational-wave detection with pulsar timing arrays
The NANOGrav 15 yr data set: Posterior predictive checks for gravitational-wave detection with pulsar timing arrays Open
Pulsar-timing-array experiments have reported evidence for a stochastic background of nanohertz gravitational waves consistent with the signal expected from a population of supermassive--black-hole binaries. Their analyses assume power-law…
View article: The second data release from the European Pulsar Timing Array
The second data release from the European Pulsar Timing Array Open
We present the results of a search for continuous gravitational wave signals (CGWs) in the second data release (DR2) of the European Pulsar Timing Array (EPTA) Collaboration. The most significant candidate event from this search has a grav…
View article: CHIME/FRB/Pulsar discovery of a nearby long period radio transient with a timing glitch
CHIME/FRB/Pulsar discovery of a nearby long period radio transient with a timing glitch Open
We present the discovery of a 421 s long period radio transient (LPT) using the CHIME telescope, CHIME J0630+25. The source is localized to RA=06:30:38.4$\pm1'$ Dec=25:26:24$\pm1'$ using voltage data acquired with the CHIME baseband system…
View article: Modeling nonstationary noise in pulsar timing array data analysis
Modeling nonstationary noise in pulsar timing array data analysis Open
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View article: The NANOGrav 15 yr Data Set: Chromatic Gaussian Process Noise Models for Six Pulsars
The NANOGrav 15 yr Data Set: Chromatic Gaussian Process Noise Models for Six Pulsars Open
Pulsar timing arrays (PTAs) are designed to detect low-frequency gravitational waves (GWs). GWs induce achromatic signals in PTA data, meaning that the timing delays do not depend on radio-frequency. However, pulse arrival times are also a…
View article: NANOGrav 15-year gravitational-wave background methods
NANOGrav 15-year gravitational-wave background methods Open
Pulsar timing arrays (PTAs) use an array of millisecond pulsars to search for gravitational waves in the nanohertz regime in pulse time of arrival data. This paper presents rigorous tests of PTA methods, examining their consistency across …
View article: Modeling non stationary noise in pulsar timing array data analysis
Modeling non stationary noise in pulsar timing array data analysis Open
Pulsar Timing Array (PTA) collaborations recently reported evidence for the presence of a gravitational wave background (GWB) in their datasets. The main candidate that is expected to produce such a GWB is the population of supermassive bl…
View article: High-cadence Timing of Binary Pulsars with CHIME
High-cadence Timing of Binary Pulsars with CHIME Open
We performed near-daily observations of the binary pulsars PSR J0218+4232, PSR J1518+4904, and PSR J2023+2853 with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). For the first time, we detected the Shapiro time delay in all th…
View article: The NANOGrav 15 yr Data Set: Looking for Signs of Discreteness in the Gravitational-wave Background
The NANOGrav 15 yr Data Set: Looking for Signs of Discreteness in the Gravitational-wave Background Open
The cosmic merger history of supermassive black hole binaries (SMBHBs) is expected to produce a low-frequency gravitational wave background (GWB). Here we investigate how signs of the discrete nature of this GWB can manifest in pulsar timi…
View article: An Unusual Pulse Shape Change Event in PSR J1713+0747 Observed with the Green Bank Telescope and CHIME
An Unusual Pulse Shape Change Event in PSR J1713+0747 Observed with the Green Bank Telescope and CHIME Open
The millisecond pulsar J1713+0747 underwent a sudden and significant pulse shape change between 2021 April 16 and 17 (MJDs 59320 and 59321). Subsequently, the pulse shape gradually recovered over the course of several months. We report the…