Joseph Glaser
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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: 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: 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-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: 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: 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: 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: 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: Exploring Pulsar Timing Precision: A Comparative Study of Polarization Calibration Methods for NANOGrav Data from the Green Bank Telescope
Exploring Pulsar Timing Precision: A Comparative Study of Polarization Calibration Methods for NANOGrav Data from the Green Bank Telescope Open
Pulsar timing array experiments have recently uncovered evidence for a nanohertz gravitational wave background by precisely timing an ensemble of millisecond pulsars. The next significant milestones for these experiments include characteri…
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: 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 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 $\pm$ 0.8 mm/s/yr, which deviates from the acceleration predicted by equilibrium Milky Way models at a $4σ$ level. The magnitu…
View article: Exploring pulsar timing precision: A comparative study of polarization calibration methods for NANOGrav data from the Green Bank Telescope
Exploring pulsar timing precision: A comparative study of polarization calibration methods for NANOGrav data from the Green Bank Telescope Open
Pulsar timing array experiments have recently uncovered evidence for a nanohertz gravitational wave background by precisely timing an ensemble of millisecond pulsars. The next significant milestones for these experiments include characteri…
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: Comparing Recent Pulsar Timing Array Results on the Nanohertz Stochastic Gravitational-wave Background
Comparing Recent Pulsar Timing Array Results on the Nanohertz Stochastic Gravitational-wave Background Open
The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational-wave background (GWB). Given that each PTA …
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 NANOGrav 15 yr Data Set: Search for Transverse Polarization Modes in the Gravitational-wave Background
The NANOGrav 15 yr Data Set: Search for Transverse Polarization Modes in the Gravitational-wave Background Open
Recently we found compelling evidence for a gravitational-wave background with Hellings and Downs (HD) correlations in our 15 yr data set. These correlations describe gravitational waves as predicted by general relativity, which has two tr…
View article: The NANOGrav 12.5 yr Data Set: A Computationally Efficient Eccentric Binary Search Pipeline and Constraints on an Eccentric Supermassive Binary Candidate in 3C 66B
The NANOGrav 12.5 yr Data Set: A Computationally Efficient Eccentric Binary Search Pipeline and Constraints on an Eccentric Supermassive Binary Candidate in 3C 66B Open
The radio galaxy 3C 66B has been hypothesized to host a supermassive black hole binary (SMBHB) at its center based on electromagnetic observations. Its apparent 1.05 yr period and low redshift (∼0.02) make it an interesting testbed to sear…
View article: The NANOGrav 12.5 yr Data Set: Search for Gravitational Wave Memory
The NANOGrav 12.5 yr Data Set: Search for Gravitational Wave Memory Open
We present the results of a Bayesian search for gravitational wave (GW) memory in the NANOGrav 12.5 yr data set. We find no convincing evidence for any gravitational wave memory signals in this data set. We find a Bayes factor of 2.8 in fa…
View article: The NANOGrav 12.5 yr Data Set: Search for Gravitational Wave Memory
The NANOGrav 12.5 yr Data Set: Search for Gravitational Wave Memory Open
We present the results of a Bayesian search for gravitational wave (GW) memory in the NANOGrav 12.5 yr data set. We find no convincing evidence for any gravitational wave memory signals in this data set. We find a Bayes factor of 2.8 in fa…