The NANOGrav 12.5-year Data Set: Wideband Timing of 47 Millisecond Pulsars
Md F. Alam, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Keith E. Bohler, Adam Brazier, Paul R. Brook, Sarah Burke-Spolaor, Keeisi Caballero, Richard S. Cam… 展开作者
Md F. Alam, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Keith E. Bohler, Adam Brazier, Paul R. Brook, Sarah Burke-Spolaor, Keeisi Caballero, Richard S. Camuccio, Rachel L. Chamberlain, Shami Chatterjee, James M. Cordes, Neil J. Cornish, Fronefield Crawford, H. Thankful Cromartie, Megan E. DeCesar, Paul B. Demorest, Timothy Dolch, Justin A. Ellis, Robert D. Ferdman, Elizabeth C. Ferrara, William Fiore, Emmanuel Fonseca, Yhamil Garcia, Nathan Garver-Daniels, Peter A. Gentile, Deborah C. Good, Jordan A. Gusdorff, Daniel Halmrast, Jeffrey S. Hazboun, Kristina Islo, Ross J. Jennings, Cody Jessup, Megan L. Jones, Andrew R. Kaiser, David L. Kaplan, Luke Zoltan Kelley, Joey Shapiro Key, Michael T. Lam, T. Joseph W. Lazio, Duncan R. Lorimer, Jing Luo, Ryan S. Lynch, Dustin Madison, Kaleb Maraccini, Maura A. McLaughlin, Chiara M. F. Mingarelli, Cherry Ng, Benjamin M. X. Nguyen, David J. Nice, Timothy T. Pennucci, Nihan S. Pol, Joshua Ramette, Scott M. Ransom, Paul S. Ray, Brent J. Shapiro-Albert, Xavier Siemens, Joseph Simon, Renee Spiewak, Ingrid H. Stairs, Daniel R. Stinebring, Kevin Stovall, Joseph K. Swiggum, Stephen R. Taylor, Michael Tripepi, Michele Vallisneri, Sarah J. Vigeland, Caitlin A. Witt, Weiwei Zhu
备注：
62 pages, 55 figures, 5 tables, 3 appendices. Data available at http://nanograv.org/data/ and via DOI 10.5281/zenodo.4312887
发表信息：
The Astrophysical Journal Supplement Series, 252, 5 (2021)
We present a new analysis of the profile data from the 47 millisecond pulsars comprising the 12.5-year data set of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), which is presented in a parallel paper (Alam et al. 2021a; NG12.5). Our reprocessing is performed using "wideband" timing methods, which use frequency-dependent template profiles, simultaneous time-of-arrival (TOA) and dispersion measure (DM) measurements from broadband observations, and novel analysis techniques. In particular, the wideband DM measurements are used to constrain the DM portion of the timing model. We compare the ensemble timing results to NG12.5 by examining the timing residuals, timing models, and noise model components. There is a remarkable level of agreement across all metrics considered. Our best-timed pulsars produce encouragingly similar results to those from NG12.5. In certain cases, such as high-DM pulsars with profile broadening, or sources that are weak and scintillating, wideband timing techniques prove to be beneficial, leading to more precise timing model parameters by 10-15%. The high-precision, multi-band measurements of several pulsars indicate frequency-dependent DMs. Compared to the narrowband analysis in NG12.5, the TOA volume is reduced by a factor of 33, which may ultimately facilitate computational speed-ups for complex pulsar timing array analyses. This first wideband pulsar timing data set is a stepping stone, and its consistent results with NG12.5 assure us that such data sets are appropriate for gravitational wave analyses.
Gravitational wave astronomy using a pulsar timing array requires high-quality millisecond pulsars, correctable interstellar propagation delays, and high-precision measurements of pulse times of arrival. Here we identify noise in timing residuals that exceeds that predicted for arrival time estimation for millisecond pulsars observed by the North American Nanohertz Observatory for Gravitational Waves. We characterize the excess noise using variance and structure function analyses. We find that 26 out of 37 pulsars show inconsistencies with a white-noise-only model based on the short timescale …
Low-frequency gravitational-wave experiments require the highest timing precision from an array of the most stable millisecond pulsars. Several known sources of noise on short timescales in single radio-pulsar observations are well described by a simple model of three components: template-fitting from a finite signal-to-noise ratio, pulse phase/amplitude jitter from single-pulse stochasticity, and scintillation errors from short-timescale interstellar scattering variations. Currently template-fitting errors dominate, but as radio telescopes push towards higher signal-to-noise ratios, jitter be…
CHIME-o-Grav: Wideband Timing of Four Millisecond Pulsars from the NANOGrav 15-yr dataset
University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校）；Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut)（马克斯·普朗克引力物理学研究所（爱因斯坦研究所））；Leibniz Universität Hannover（汉诺威莱布尼茨大学）；University of British Columbia（不列颠哥伦比亚大学）；University of Montana（蒙大拿大学）；Curtin University（科廷大学）；West Virginia University（西弗吉尼亚大学）；Eötvös Loránd University（罗兰大学）
We search for extrasolar planets around millisecond pulsars using pulsar timing data and seek to determine the minimum detectable planetary masses as a function of orbital period. Using the 11-year data set from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), we look for variations from our models of pulse arrival times due to the presence of exoplanets. No planets are detected around the millisecond pulsars in the NANOGrav 11-year data set, but taking into consideration the noise levels of each pulsar and the sampling rate of our observations, we develop limits th…
Gravitational wave (GW) detection with pulsar timing arrays (PTAs) requires accurate noise characterization. The noise of our Galactic-scale GW detector has been systematically evaluated by the Noise Budget and Interstellar Medium Mitigation working groups within the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration. Intrinsically, individual radio millisecond pulsars (MSPs) used by NANOGrav can have some degree of achromatic red spin noise, as well as white noise due to pulse phase jitter. Along any given line-of-sight, the ionized interstellar medium contr…
Using the nine-year radio-pulsar timing data set from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), collected at Arecibo Observatory and the Green Bank Telescope, we have measured the positions, proper motions, and parallaxes for 37 millisecond pulsars. We report twelve significant parallax measurements and distance measurements, and eighteen lower limits on distance. We compare these measurements to distances predicted by the NE2001 interstellar electron density model and find them to be in general agreement. We use measured orbital-decay rates and spin-down rat…
We present high-precision timing data over time spans of up to 11 years for 45 millisecond pulsars observed as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project, aimed at detecting and characterizing low-frequency gravitational waves. The pulsars were observed with the Arecibo Observatory and/or the Green Bank Telescope at frequencies ranging from 327 MHz to 2.3 GHz. Most pulsars were observed with approximately monthly cadence, with six high--timing-precision pulsars observed weekly, and all were observed at widely separated frequencies at each observ…
We present time-of-arrival (TOA) measurements and timing models of 47 millisecond pulsars (MSPs) observed from 2004 to 2017 at the Arecibo Observatory and the Green Bank Telescope by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). The observing cadence was three to four weeks for most pulsars over most of this time span, with weekly observations of six sources. These data were collected for use in low-frequency gravitational wave searches and for other astrophysical purposes. We detail our observational methods and present a set of TOA measurements, based on "narro…
We analyze 24 binary radio pulsars in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) nine-year data set. We make fourteen significant measurements of Shapiro delay, including new detections in four pulsar-binary systems (PSRs J0613$-$0200, J2017+0603, J2302+4442, and J2317+1439), and derive estimates of the binary-component masses and orbital inclination for these MSP-binary systems. We find a wide range of binary pulsar masses, with values as low as $m_{\rm p} = 1.18^{+0.10}_{-0.09}\text{M}_{\odot}$ for PSR J1918$-$0642 and as high as $m_{\rm p} = 1.928^{+0.017}_{…
An ensemble of inspiraling supermassive black hole binaries should produce a stochastic background of very low frequency gravitational waves. This stochastic background is predicted to be a power law, with a spectral index of -2/3, and it should be detectable by a network of precisely timed millisecond pulsars, widely distributed on the sky. This paper reports a new "time slicing" analysis of the 11-year data release from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) using 34 millisecond pulsars. Methods to flag potential "false positive" signatures are developed,…
Access to 50 years of data has led to the discovery of pulsar emission and rotation variability on timescales of months and years. Most of this long-term variability has been seen in long-period pulsars, with relatively little focus on recycled millisecond pulsars. We have analyzed a 38-pulsar sub-set of the 45 millisecond pulsars in the NANOGrav 11-year data set, in order to review their pulse profile stability. The most variability, on any timescale, is seen in PSRs J1713+0747, B1937+21 and J2145-0750. The strongest evidence for long-timescale pulse profile changes is seen in PSRs B1937+21 a…
We report the first wideband monitoring observations of PSR J1803-3002A, a relatively bright millisecond pulsar in the globular cluster NGC 6522 with a spin period of 7.1 ms and no known binary companion. These observations were performed using the Parkes 64-m radio telescope with the Ultra-Wideband Low (UWL) receiver system, which covers 704 to 4032 MHz. We confirm that PSR J1803-3002A is an isolated millisecond pulsar located near the cluster center and probe the emission properties of the pulsar over the wide observed band. The mean pulse profile consists of three components, with the outer…
We analyze timing noise from five years of Arecibo and Green Bank observations of the seventeen millisecond pulsars of the North-American Nanohertz Observatory for Gravitational Waves (NANOGrav) pulsar timing array. The weighted autocovariance of the timing residuals was computed for each pulsar and compared against two possible models for the underlying noise process. The first model includes red noise and predicts the autocovariance to be a decaying exponential as a function of time lag. The second model is Gaussian white noise whose autocovariance would be a delta function. We also perform …
In 2018 an ultra-wide-bandwidth low-frequency (UWL) receiver was installed on the 64-m Parkes Radio Telescope enabling observations with an instantaneous frequency coverage from 704 to 4032 MHz. Here, we present the analysis of a three-year data set of 35 millisecond pulsars observed with the UWL by the Parkes Pulsar Timing Array (PPTA), using wideband timing methods. The two key differences compared to typical narrow-band methods are, firstly, generation of two-dimensional templates accounting for pulse shape evolution with frequency and, secondly, simultaneous measurements of the pulse time-…
We analyze dispersion measure (DM) variations of 37 millisecond pulsars in the 9-year NANOGrav data release and constrain the sources of these variations. Variations are significant for nearly all pulsars, with characteristic timescales comparable to or even shorter than the average spacing between observations. Five pulsars have periodic annual variations, 14 pulsars have monotonically increasing or decreasing trends, and 13 pulsars show both effects. Several pulsars show correlations between DM excesses and lines of sight that pass close to the Sun. Mapping of the DM variations as a function…
We present the polarization pulse profiles for 28 pulsars observed with the Arecibo Observatory by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) timing project at 2.1 GHz, 1.4 GHz, and 430 MHz. These profiles represent some of the most sensitive polarimetric millisecond pulsar profiles to date, revealing the existence of microcomponents (that is, pulse components with peak intensities much lower than the total pulse peak intensity). Although microcomponents have been detected in some pulsars previously, we present microcomponents for PSRs B1937+21, J1713+0747, and…
To successfully detect gravitational waves with pulsar timing arrays, we need to have a comprehensive understanding of the physical origins and statistical characteristics of the noise in pulse arrival times and identify mitigation methods to reduce the noise. In this paper we will review radiometer noise, phase jitter noise and timing noise in the noise budget of pulsar timing and show various efforts used to reduce them. We will briefly discuss the results of an overall assessment of the components and physical causes of the timing residuals for millisecond pulsars in the North American Nano…
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project has the primary goal of detecting and characterizing low-frequency gravitational waves through high-precision pulsar timing. The mitigation of interstellar effects is crucial to achieve the necessary precision for gravitational wave detection. Effects like dispersion and scattering are more influential at lower observing frequencies, with the variation of these quantities over week-month timescales requiring high-cadence multi-frequency observations for pulsar timing projects. In this work, we utilize the dual-…
While observations of many high-precision radio pulsars of order $\lesssim1~μ$s across the sky are needed for the detection and characterization of a stochastic background of low-frequency gravitational waves (GWs), sensitivity to single sources of GWs requires even higher timing precision. The Argentine Institute of Radio Astronomy (IAR; Instituto Argentino de Radioastronomía) has begun observations of the brightest-known millisecond pulsar, J0437$-$4715. Even though the two antennas are smaller than other single-dish telescopes previously used for pulsar timing array (PTA) science, the IAR's…
Millisecond pulsars are intrinsically very stable clocks and precise measurement of their observed pulse periods can be used to study a wide variety of astrophysical phenomena. In particular, observations of a large sample of millisecond pulsars at regular intervals, constituting a Pulsar Timing Array (PTA), can be used as a detector of low-frequency gravitational waves and to establish a standard of time independent of terrestrial atomic timescales. Three major timing array projects have been established: The European Pulsar Timing Array (EPTA), the North American pulsar timing array (NANOGra…
Frequency- and phase-resolved polarimetry of millisecond pulsars and its application to timing
Monash University（莫纳什大学）；OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery（ARC引力波发现卓越中心）；Australia Telescope National Facility, CSIRO（澳大利亚国家望远镜设施，CSIRO）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理学研究所（爱因斯坦研究所））；Leibniz Universität Hannover（汉诺威莱布尼茨大学）；Hunan Normal University（湖南师范大学）
We present an algorithm for the simultaneous measurement of a pulse time-of-arrival (TOA) and dispersion measure (DM) from folded wideband pulsar data. We extend the prescription from Taylor (1992) to accommodate a general two-dimensional template "portrait", the alignment of which can be used to measure a pulse phase and DM. We show that there is a dedispersion reference frequency that removes the covariance between these two quantities, and note that the recovered pulse profile scaling amplitudes can provide useful information. We experiment with pulse modeling by using a Gaussian-component …
Pulsar timing experiments require high fidelity template profiles in order to minimize the biases in pulse time-of-arrival (TOA) measurements and their uncertainties. Efforts to acquire more precise TOAs given fixed effective area of telescopes, finite receiver noise, and limited integration time have led pulsar astronomers to the solution of implementing ultra-wideband receivers. This solution, however, has run up against the problem that pulse profile shapes evolve with frequency, which raises the question of how to properly measure and analyze TOAs obtained using template-matching methods. …
Dense, continuous pulsar timing observations over a 24-hr period provide a method for probing intermediate gravitational wave (GW) frequencies from 10 microhertz to 20 millihertz. The European Pulsar Timing Array (EPTA), the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), the Parkes Pulsar Timing Array (PPTA), and the combined International Pulsar Timing Array (IPTA) all use millisecond pulsar observations to detect or constrain GWs typically at nanohertz frequencies. In the case of the IPTA's nine-telescope 24-Hour Global Campaign on millisecond pulsar J1713+0747, GW …
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) is a collaboration of researchers who are actively engaged in using North American radio telescopes to detect and study gravitational waves via pulsar timing. To achieve this goal, we regularly observe millisecond pulsars (MSPs) with the Arecibo and Green Bank Telescopes and develop and implement new instrumentation and algorithms for searching for and observing pulsars, calculating arrival times, understanding and correcting for propagation delays and sources of noise in our data, and detecting and characterizing a va…
Despite its importance to our understanding of physics at supranuclear densities, the equation of state (EoS) of matter deep within neutron stars remains poorly understood. Millisecond pulsars (MSPs) are among the most useful astrophysical objects in the Universe for testing fundamental physics, and place some of the most stringent constraints on this high-density EoS. Pulsar timing - the process of accounting for every rotation of a pulsar over long time periods - can precisely measure a wide variety of physical phenomena, including those that allow the measurement of the masses of the compon…
Ultra-Wideband Polarimetry of the April 2021 Profile Change Event in PSR J1713+0747
Macquarie University（麦考瑞大学）；Australia Telescope National Facility, CSIRO（澳大利亚望远镜国家设施，CSIRO）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；School of Physics and Astronomy, Monash University（蒙纳士大学物理与天文学学院）；Space Science Division, Naval Research Laboratory（海军研究实验室空间科学部）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理学与超级计算中心）
Discovery of Two Consecutive Profile Change Events in the Millisecond Pulsar PSR J0437-4715
Macquarie University（麦考瑞大学）；Australia Telescope National Facility, CSIRO（澳大利亚望远镜国家设施，CSIRO）；OzGrav: The ARC Center of Excellence for Gravitational Wave Discovery（OzGrav：ARC引力波发现卓越中心）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；School of Physics and Astronomy, Monash University（蒙纳士大学物理与天文学学院）
Searching for links between energetic millisecond pulsars and repeating fast radio bursts
Anton Pannekoek Institute for Astronomy, University of Amsterdam（阿姆斯特丹大学安东·潘内科克天文学研究所）；ASTRON, Netherlands Institute for Radio Astronomy（荷兰射电天文研究所 ASTRON）；Department of Physics, McGill University（麦吉尔大学物理系）；Trottier Space Institute, McGill University（麦吉尔大学特罗蒂尔太空研究所）；Joint institute for VLBI ERIC（甚长基线干涉测量联合研究所 ERIC）；CSIRO Space and Astronomy, Australia Telescope National Facility（澳大利亚联邦科学与工业研究组织空间与天文部，澳大利亚望远镜国家设施）
The GMRT High-Resolution Southern Sky Survey for pulsars and transients -- VIII: Orbital Variability and the Evolution of a 1-Day He-WD Millisecond Pulsar J2101-4802
National Centre For Radio Astrophysics, Tata Institute of Fundamental Research（塔塔基础研究所射电天体物理国家中心）；Center for Gravitation, Cosmology, and Astrophysics, Department of Physics, University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校物理系引力、宇宙学与天体物理中心）；Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS（波尔多大学CNRS波尔多天体物理实验室）；Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester（曼彻斯特大学物理与天文学院乔德雷尔银行天体物理中心）
The Argentine Institute of Radio astronomy (IAR) is equipped with two single-dish 30mts radio antennas capable of performing daily observations of pulsars and radio transients in the southern hemisphere at 1.4 GHz. We aim to introduce to the international community the upgrades performed and to show that IAR observatory has become suitable for investigations in numerous areas of pulsar radio astronomy, such as pulsar timing arrays, targeted searches of continuous gravitational waves sources, monitoring of magnetars and glitching pulsars, and studies of short time scale interstellar scintillati…
We present the pulse arrival times and high-precision dispersion measure estimates for 14 millisecond pulsars observed simultaneously in the 300-500 MHz and 1260-1460 MHz frequency bands using the upgraded Giant Metrewave Radio Telescope (uGMRT). The data spans over a baseline of 3.5 years (2018-2021), and is the first official data release made available by the Indian Pulsar Timing Array collaboration. This data release presents a unique opportunity for investigating the interstellar medium effects at low radio frequencies and their impact on the timing precision of pulsar timing array experi…
A nanohertz-frequency stochastic gravitational-wave background can potentially be detected through the precise timing of an array of millisecond pulsars. This background produces low-frequency noise in the pulse arrival times that would have a characteristic spectrum common to all pulsars and a well-defined spatial correlation. Recently the North American Nanohertz Observatory for Gravitational Waves collaboration (NANOGrav) found evidence for the common-spectrum component in their 12.5-year data set. Here we report on a search for the background using the second data release of the Parkes Pul…
Pulsar Timing Arrays (PTA) around the world are using the incredible consistency of millisecond pulsars to measure low frequency gravitational waves from (super)Massive Black Hole (MBH) binaries. We use comprehensive MBH merger models based on cosmological hydrodynamic simulations to predict the spectrum of the stochastic Gravitational-Wave Background (GWB). We use real Time-of-Arrival (TOA) specifications from the European, NANOGrav, Parkes, and International PTA (IPTA) to calculate realistic times to detection of the GWB across a wide range of model parameters. In addition to exploring the p…
Mitigating the Timing Impact of Anomalous Pulse Profile Shape Variability in PSR J1713+0747 with Gaussian Component Modeling
NANOGrav Physics Frontiers Center（NANOGrav物理前沿中心）；SETI Institute（SETI研究所）；Center for Gravitation, Cosmology and Astrophysics, Department of Physics and Astronomy, University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校物理与天文学系引力、宇宙学与天体物理中心）；Department of Physics, Oregon State University（俄勒冈州立大学物理系）；Department of Physics and Astronomy, Vanderbilt University（范德堡大学物理与天文学系）；Department of Physics and Astronomy, University of British Columbia（不列颠哥伦比亚大学物理与天文学系）；Department of Physics and Astronomy, George Mason University（乔治梅森大学物理与天文学系）；National Radio Astronomy Observatory（美国国家射电天文台）；Institute of Astrophysics, FORTH（希腊基础与研究基金会天体物理研究所）
Recycled pulsars are old ($\gtrsim10^{8}$ yr) neutron stars that are descendants from close, interacting stellar systems. In order to understand their evolution and population, we must find and study the largest number possible of recycled pulsars in a way that is as unbiased as possible. In this work, we present the discovery and timing solutions of five recycled pulsars in binary systems (PSRs J0509$+$0856, J0709$+$0458, J0732$+$2314, J0824$+$0028, J2204$+$2700) and one isolated millisecond pulsar (PSR J0154$+$1833). These were found in data from the Arecibo 327-MHz Drift-Scan Pulsar Survey …
Optimal Pulsar Timing Array Strategies with the Deep Synoptic Array
New Mexico Institute of Mining and Technology（新墨西哥矿业理工学院）；National Radio Astronomy Observatory（国家射电天文台）；Oregon State University（俄勒冈州立大学）；Green Bank Observatory（格林班克天文台）；SETI Institute（SETI研究所）；University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校）；University of North Carolina, Chapel Hill（北卡罗来纳大学教堂山分校）；Newcastle University（纽卡斯尔大学）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；Widener University（韦德纳大学）；Lafayette College（拉斐特学院）；Institute for Gravitational Wave Astr（引力波天体物理研究所）
MeerTime is a five-year Large Survey Project to time pulsars with MeerKAT, the 64-dish South African precursor to the Square Kilometre Array. The science goals for the programme include timing millisecond pulsars (MSPs) to high precision (< 1 $μ$s) to study the Galactic MSP population and to contribute to global efforts to detect nanohertz gravitational waves with the International Pulsar Timing Array (IPTA). In order to plan for the remainder of the programme and to use the allocated time most efficiently, we have conducted an initial census with the MeerKAT "L-band" receiver of 189 MSPs visi…
We report on Bayesian estimation of the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740$+$6620, conditional on pulse-profile modeling of Neutron Star Interior Composition Explorer X-ray Timing Instrument (NICER XTI) event data. We condition on informative pulsar mass, distance, and orbital inclination priors derived from the joint NANOGrav and CHIME/Pulsar wideband radio timing measurements of arXiv:2104.00880. We use XMM European Photon Imaging Camera spectroscopic event data to inform our X-ray likelihood function. The prior support of the pulsar radius is t…
Evaluating the Fourier Approximation in Pulsar Timing Array Analysis
Tufts University（塔夫茨大学）；Cornell University（康奈尔大学）；University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校）；University of North Carolina, Chapel Hill（北卡罗来纳大学教堂山分校）；Newcastle University（纽卡斯尔大学）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；Widener University（韦德纳大学）；University of Birmingham（伯明翰大学）；National Research Council Research Associate, National Academy of Sciences（美国国家研究委员会/美国国家科学院）
Probing turbulence in the ionized interstellar medium using young pulsars. I. Dispersion measure variations
ASTRON, Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）；Anton Pannekoek Institute for Astronomy, University of Amsterdam（阿姆斯特丹大学安东·潘内科克天文学研究所）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Australia Telescope National Facility, CSIRO（澳大利亚望远镜国家设施，CSIRO）；LPC2E, OSUC, Univ Orleans, CNRS, CNES, Observatoire de Paris（奥尔良大学 LPC2E 实验室）；Space Science Division, Naval Research Laboratory（海军研究局空间科学分部）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理学与超级计算中心）
