On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4}  years. We infer the component masses of the binary to be between 0.86 and 2.26  M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60  M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28  deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8}  Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.

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GW170817: observation of gravitational waves from a binary neutron star inspiral

This book presents a comprehensive review of the subject of gravitational effects in quantum field theory. Although the treatment is general, special emphasis is given to the Hawking black hole evaporation effect, and to particle creation processes in the early universe. The last decade has witnessed a phenomenal growth in this subject. This is the first attempt to collect and unify the vast literature that has contributed to this development. All the major technical results are presented, and the theory is developed carefully from first principles. Here is everything that students or researchers will need to embark upon calculations involving quantum effects of gravity at the so-called one-loop approximation level.

Quantum Fields in Curved Space

Modified Gravity and Cosmology

The status of experimental tests of general relativity and of theoretical frameworks for analyzing them is reviewed and updated. Einstein’s equivalence principle (EEP) is well supported by experiments such as the Eotvos experiment, tests of local Lorentz invariance and clock experiments. Ongoing tests of EEP and of the inverse square law are searching for new interactions arising from unification or quantum gravity. Tests of general relativity at the post-Newtonian level have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, the Nordtvedt effect in lunar motion, and frame-dragging. Gravitational wave damping has been detected in an amount that agrees with general relativity to better than half a percent using the Hulse-Taylor binary pulsar, and a growing family of other binary pulsar systems is yielding new tests, especially of strong-field effects. Current and future tests of relativity will center on strong gravity and gravitational waves.

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The Confrontation Between General Relativity and Experiment

We have compiled a new and complete catalog of the main properties of the 1509 pulsars for which published information currently exists. The catalog includes all spin-powered pulsars, as well as anomalous X-ray pulsars and soft gamma-ray repeaters showing coherent pulsed emission, but excludes accretion-powered systems. References are given for all data listed. We have also developed a new World Wide Web interface for accessing and displaying either tabular or plotted data with the option of selecting pulsars to be displayed via logical conditions on parameter expressions. The Web interface has an expert mode giving access to a wider range of parameters and allowing the use of custom databases. For users with locally installed software and database on Unix or Linux systems, the catalog may be accessed from a command-line interface. C-language functions to access specified parameters are also available. The catalog is updated from time to time to include new information.

https://iopscience.iop.org/article/10.1086/428488/pdf

The Australia Telescope National Facility Pulsar Catalogue

We have detected a pulsar with a pulsation period that varies systematically between 0.058967 and 0.059045 sec over a cycle of 0.3230 d. Approximately 200 independent observations over 5-minute intervals have yielded a well-sampled velocity curve which implies a binary orbit with projected semimajor axis sin i = 1.0 solar radius, eccentricity e = 0.615, and mass function f(m) = 0.13 solar mass. No eclipses are observed. We infer that the unseen companion is a compact object with mass comparable to that of the pulsar. In addition to the obvious potential for determining the masses of the pulsar and its companion, this discovery makes feasible a number of studies involving the physics of compact objects, the astrophysics of close binary systems, and special- and general-relativistic effects.

Discovery of a pulsar in a binary system

The present quantitative model for Galactic free electron distribution abandons the assumption of axisymmetry and explicitly incorporates spiral arms; their shapes and locations are derived from existing radio and optical observations of H II regions. The Gum Nebula's dispersion-measure contributions are also explicitly modeled. Adjustable quantities are calibrated by reference to three different types of data. The new model is estimated to furnish distance estimates to known pulsars that are accurate to about 25 percent.

Pulsar distances and the galactic distribution of free electrons

Afin d'etablir des conclusions statistiques sur la population globale des pulsars dans la Galaxie, on analyse un echantillon de 316 pulsars detectes

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The galactic population of pulsars

Over much of the past year, Russell A. Hulse and 1 have been conducting a high-sensitivity search for previously unknown pulsars with the 1000-ft telescope at the Arecibo Observatory.’.’ Our survey is about 20 times more sensitive than any of the previous efforts to detect new pulsars, thanks to the large collecting area of the Arecibo antenna and the use of an automated “pulsar-finding machine” that we have constructed at the University of Massachusetts. This equipment includes a 64-channel filter-type receiver interfaced directly to a small computer. When the survey is in progress, the sky is scanned at the rate of about 20 beam areas (-0.5 square degrees) per hour; for each beam area, the computer applies to the data more than lo6 different matched digital filters and thereby seeks periodicities in the range 0.03 < P < 3.9s, dispersion measures in the range 0 < DM < 1240, and pulse duty cycles between h a n d A. When searching the sky at galactic latitudes 16 1 < 5 ” , we find an average of one new pulsar every 8 hr. A total of 50 pulsars have been detected, of which 40 were not previously known. The most interesting of the newly discovered pulsars is PSR 1913+ 16, which has a period of -0S.059 and which undergoes periodic Doppler shifts, indicating that it is a member of a binary ~ y s t e m . ~ Observed parameters of the pulsar are given in TABLE I , which lists celestial and galactic coordinates, pulsation period, upper limit to period derivative, dispersion measure, average flux density at 430 MHz, and effective pulse width. The period given in this Table is corrected to the solar system barycenter and the center of mass of the binary system; however, motion of the pulsar in its orbit causes the solar system barycentric period to vary between 0958967 and 0959045. A total of 54 hr of data on the pulsar have been accumulated, over a span of 80 days that ended December 3, 1974. Analyzed in segments each 5 min in length, the data provide 650 independent measurements of pulsation period, with accuracies of the order of 0.5 psec. When analyzed with a linearized least-squares fitting program, the data yield orbital elements as shown in TABLE 2. The elements determine the observed period P&s through the equation

We estimate the coalescence rate of close binaries with two neutron stars (NS) and discuss the prospects for the detection of NS-NS inspiral events by ground-based gravitational-wave observatories, such as LIGO. We derive the Galactic coalescence rate using the observed sample of close NS-NS binaries (PSR B1913+16 and PSR B1534+12) and examine in detail each of the sources of uncertainty associated with the estimate. Specifically, we investigate (1) the dynamical evolution of NS-NS binaries in the Galactic potential and the vertical scale height of the population, (2) the pulsar lifetimes, (3) the effects of the faint end of the radio pulsar luminosity function and their dependence on the small number of observed objects, (4) the beaming fraction, and (5) the extrapolation of the Galactic rate to extragalactic distances expected to be reachable by LIGO. We find that the dominant source of uncertainty is the correction factor (up to 200) for faint (undetectable) pulsars. All other sources are much less important, each with uncertainty factors smaller than 2. Despite the relatively large uncertainty, the derived coalescence rate is consistent with previously derived upper limits, and is more accurate than rates obtained from population studies. We obtain a most conservative lower limit that the detection rate by LIGO II of about 2 events per year. Our upper limit on the rate is between 300 and 1000 events per year.

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J. H. Taylor

Papers

Discovery of a pulsar in a binary system

Pulsar distances and the galactic distribution of free electrons

The galactic population of pulsars

Discovery of a pulsar in a binary system

The coalescence rate of double neutron star systems