The North American Nanohertz Observatory for Gravitational Waves

McLaughlin, M. A.

doi:10.1088/0264-9381/30/22/224008

Cited by 348 publications

(234 citation statements)

References 66 publications

Supporting

Mentioning

232

Contrasting

Order By: Relevance

“…PSRJ1713+0747 is one of the best-timed pulsars observed by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav;McLaughlin 2013). Previously, a chromatic timing event-that is, a relatively sudden, frequencydependent change in timing properties-was seen in the TOAs starting at approximately MJD54750, interpreted as a DM drop of ≈6×10 −4 pc cm −3 and lasting for ∼100-200 days before returning to the previous DM value; the event was seen in other data sets as well (Demorest et al 2013;Keith et al 2013;Desvignes et al 2016;Jones et al 2017).…”

Section: Introductionmentioning

confidence: 99%

A Second Chromatic Timing Event of Interstellar Origin toward PSR J1713+0747

Lam

Ellis

Grillo

et al. 2018

ApJ

View full text Add to dashboard Cite

The frequency dependence of radio pulse arrival times provides a probe of structures in the intervening media. Demorest et al. was the first to show a short-term (∼100-200 days) reduction in the electron content along the line of sight to PSRJ1713+0747 in data from 2008 (approximately MJD 54750) based on an apparent dip in the dispersion measure of the pulsar. We report on a similar event in 2016 (approximately MJD 57510), with average residual pulse-arrival times ≈−3.0, −1.3, and −0.7 μs at 820, 1400, and 2300MHz, respectively. Timing analyses indicate possible departures from the standard ν −2 dispersive-delay dependence. We discuss and rule out a wide variety of potential interpretations. We find the likeliest scenario to be lensing of the radio emission by some structure in the interstellar medium, which causes multiple frequency-dependent pulse arrival-time delays.

show abstract

Section: Introductionmentioning

confidence: 99%

A Second Chromatic Timing Event of Interstellar Origin toward PSR J1713+0747

Lam

Ellis

Grillo

et al. 2018

ApJ

View full text Add to dashboard Cite

show abstract

“…The principal goal of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav;McLaughlin 2013) is to detect gravitational waves in the nanohertz regime of the gravitational wave spectrum using a pulsar timing array (PTA). Sensitivity improves as more millisecond pulsars (MSPs) are added to the PTA, and therefore it is essential to have as many well-timed MSPs as possible (Siemens et al 2013;Vigeland & Siemens 2016).…”

Section: Introductionmentioning

confidence: 99%

The NANOGrav Nine-year Data Set: Measurement and Analysis of Variations in Dispersion Measures

Jones

McLaughlin

Lam

et al. 2017

ApJ

View full text Add to dashboard Cite

We analyze dispersion measure (DM) variations of 37 millisecond pulsars in the nine-year North American Nanohertz Observatory for Gravitational Waves (NANOGrav) data release and constrain the sources of these variations. DM variations can result from a changing distance between Earth and the pulsar, inhomogeneities in the interstellar medium, and solar effects. 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 14 pulsars show both effects. Of the four pulsars with linear trends that have line-of-sight velocity measurements, three are consistent with a changing distance and require an overdensity of free electrons local to the pulsar. 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 of the pulsar trajectory can identify localized interstellar medium features and, in one case, an upper limit to the size of the dispersing region of 4 au. Four pulsars show roughly Kolmogorov structure functions (SFs), and another four show SFs less steep than Kolmogorov. One pulsar has too large an uncertainty to allow comparisons. We discuss explanations for apparent departures from a Kolmogorov-like spectrum, and we show that the presence of other trends and localized features or gradients in the interstellar medium is the most likely cause.

show abstract

“…In the nanohertz frequency range (1-100 nHz), high-precision timing observations of millisecond pulsars (pulsar timing arrays -PTAs) provide a unique means of detecting GWs. With the concept proposed decades ago (Sazhin 1978;Detweiler 1979;Hellings & Downs 1983;Foster & Backer 1990), there are now three major PTA projects around the globe, namely, the Parkes Pulsar Timing Array (PPTA; Hobbs 2013), the European Pulsar Timing Array (Kramer & Champion 2013), and NANOGrav (McLaughlin 2013). While these PTAs have individually collected high-quality data spanning 5 yrs for ∼20 pulsars and produced some astrophysically interesting results (e.g., Shannon et al 2013), they have also been combined to form the International Pulsar Timing Array (IPTA; Hobbs et al 2010;) aiming at significantly enhanced sensitivities.…”

Section: Introductionmentioning

confidence: 99%

Detection and localization of single-source gravitational waves with pulsar timing arrays

Zhu¹,

Wen²,

Hobbs³

et al. 2015

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Pulsar timing arrays (PTAs) can be used to search for very low frequency (10 −9 -10 −7 Hz) gravitational waves (GWs). In this paper we present a general method for the detection and localization of single-source GWs using PTAs. We demonstrate the effectiveness of this new method for three types of signals: monochromatic waves as expected from individual supermassive binary black holes in circular orbits, GWs from eccentric binaries and GW bursts. We also test its implementation in realistic data sets that include effects such as uneven sampling and heterogeneous data spans and measurement precision. It is shown that our method, which works in the frequency domain, performs as well as published time-domain methods. In particular, we find it equivalent to the F e -statistic for monochromatic waves. We also discuss the construction of null streams -data streams that have null response to GWs, and the prospect of using null streams as a consistency check in the case of detected GW signals. Finally, we present sensitivities to individual supermassive binary black holes in eccentric orbits. We find that a monochromatic search that is designed for circular binaries can efficiently detect eccentric binaries with both high and low eccentricities, while a harmonic summing technique provides greater sensitivities only for binaries with moderate eccentricities.

show abstract

The North American Nanohertz Observatory for Gravitational Waves

Cited by 348 publications

References 66 publications

A Second Chromatic Timing Event of Interstellar Origin toward PSR J1713+0747

A Second Chromatic Timing Event of Interstellar Origin toward PSR J1713+0747

The NANOGrav Nine-year Data Set: Measurement and Analysis of Variations in Dispersion Measures

Detection and localization of single-source gravitational waves with pulsar timing arrays

Contact Info

Product

Resources

About