Author Correction: Superluminal motion of a relativistic jet in the neutron-star merger GW170817

ABSTRACT We perform 3D general-relativistic magnetohydrodynamic simulations to model the jet break-out from the ejecta expected to be produced in a binary neutron-star merger. The structure of the relativistic outflow from the 3D simulation confirms our previous results from 2D simulations, namely, that a relativistic magnetized outflow breaking out from the merger ejecta exhibits a hollow core of θcore ≈ 4°, an opening angle of θjet ≳ 10°, and is accompanied by a wind of ejected matter that will contribute to the kilonova emission. We also compute the non-thermal afterglow emission of the relativistic outflow and fit it to the panchromatic afterglow from GRB170817A, together with the superluminal motion reported from VLBI observations. In this way, we deduce an observer angle of $\theta _{\rm obs}= 35.7^{\circ \, \, +1.8}_{\phantom{\circ \, \, }-2.2}$. We further compute the afterglow emission from the ejected matter and constrain the parameter space for a scenario in which the matter responsible for the thermal kilonova emission will also lead to a non-thermal emission yet to be observed.

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A Study of Gamma Spectral Break in AGN

Symposium - International Astronomical Union ◽

10.1017/s0074180900175485 ◽

1994 ◽

Vol 159 ◽

pp. 347-347

Author(s):

A. Marcowith ◽

G. Henri ◽

G. Pelletier

Keyword(s):

Pair Production ◽

Flow Model ◽

Photon Absorption ◽

Compact Region ◽

Pair Plasma ◽

Relativistic Jet ◽

Spectral Break ◽

Superluminal Motion ◽

Γ Rays ◽

Relativistic Pair

Since its launch, CGRO has detected more than 20 γ-ray emitting AGN, most of them associated with powerful, radio-loud, flat-spectrum objects, exhibiting VLBI superluminal motions. In the case of 3C279, the huge value of the apparent luminosity (∼ 1048erg.s−1) and the variability time-scale of a few days (Hartmann et al., 1992) gives a very large compacity lapp ≃ 200, that is, the medium should be completely thick to γ-rays. This contradiction can be explained if the γ-rays originate from a relativistic jet pointing at a small angle with respect to the line of sight (Maraschi et al., 1992). However, the still large value of compacity suggests the existence of an inner, more compact region where pair production can take place efficiently (Henri et al., 1993). This supports the so-called “two-flow” model, where the superluminal motion is attributed to the expansion of a relativistic pair plasma heated by a MHD jet from an accretion disk (Sol et al., 1989). Hence we propose to interpret the spectral break observed in many objects around a few MeV (Lichti et al., 1993) by an opacity effect due to photon-photon absorption by pair production.

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The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VI. Radio Constraints on a Relativistic Jet and Predictions for Late-time Emission from the Kilonova Ejecta

The Astrophysical Journal ◽

10.3847/2041-8213/aa905d ◽

2017 ◽

Vol 848 (2) ◽

pp. L21 ◽

Cited By ~ 160

Author(s):

K. D. Alexander ◽

E. Berger ◽

W. Fong ◽

P. K. G. Williams ◽

C. Guidorzi ◽

...

Keyword(s):

Neutron Star ◽

Late Time ◽

Binary Neutron Star ◽

Relativistic Jet

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Binary Neutron Star (BNS) Merger: What We Learned from Relativistic Ejecta of GW/GRB 170817A

Physics ◽

10.3390/physics1020018 ◽

2019 ◽

Vol 1 (2) ◽

pp. 194-228 ◽

Cited By ~ 1

Author(s):

Houri Ziaeepour

Keyword(s):

Neutron Star ◽

Gravitational Waves ◽

Gamma Ray ◽

Lorentz Factor ◽

Prompt Gamma ◽

External Shocks ◽

Binary Neutron Star ◽

Tidal Forces ◽

Relativistic Jet ◽

Short Grbs

Gravitational Waves (GW) from coalescence of a Binary Neutron Star (BNS) and its accompanying short Gamma-Ray Burst (GRB) GW/GRB 170817A confirmed the presumed origin of these puzzling transients and opened up the way for relating properties of short GRBs to those of their progenitor stars and their surroundings. Here we review an extensive analysis of the prompt gamma-ray and late afterglows of this event. We show that a fraction of polar ejecta from the merger had been accelerated to ultra-relativistic speeds. This structured jet had an initial Lorentz factor of about 260 in our direction, which was O ( 10 ∘ ) from the jet’s axis, and was a few orders of magnitude less dense than in typical short GRBs. At the time of arrival to circum-burst material the ultra-relativistic jet had a close to Gaussian profile and a Lorentz factor ≳ 130 in its core. It had retained in some extent its internal collimation and coherence, but had extended laterally to create mildly relativistic lobes—a cocoon. Its external shocks on the far from center inhomogeneous circum-burst material and low density of colliding shells generated slowly rising afterglows, which peaked more than 100 days after the prompt gamma-ray. The circum-burst material was somehow correlated with the merger. As non-relativistic outflows or tidally ejected material during BNS merger could not have been arrived to the location of the external shocks before the relativistic jet, circum-burst material might have contained recently ejected materials from resumption of internal activities, faulting and mass loss due to deformation and breaking of stars crusts by tidal forces during latest stages of their inspiral but well before their merger. By comparing these findings with the results of relativistic Magneto-Hydro-Dynamics (MHD) simulations and observed gravitational waves we conclude that progenitor neutron stars were most probably old, had close masses and highly reduced magnetic fields.

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Jet Propagation in Neutron Star Mergers and GW170817

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3231 ◽

2019 ◽

Cited By ~ 10

Author(s):

Hamid Hamidani ◽

Kenta Kiuchi ◽

Kunihito Ioka

Keyword(s):

Neutron Star ◽

Numerical Simulations ◽

Gamma Ray ◽

Galactic Nuclei ◽

Expansion Velocity ◽

Analytic Model ◽

Binary Neutron Star ◽

Central Engine ◽

Relativistic Jet ◽

Wave Event

Abstract The gravitational wave event from the binary neutron star (BNS) merger GW170817 and the following multi-messenger observations present strong evidence for i) merger ejecta expanding with substantial velocities and ii) a relativistic jet which had to propagate through the merger ejecta. The ejecta’s expansion velocity is not negligible for the jet head motion, which is a fundamental difference from the other systems like collapsars and active galactic nuclei. Here we present an analytic model of the jet propagation in an expanding medium. In particular, we notice a new term in the expression of the breakout time and velocity. In parallel, we perform a series of over a hundred 2D numerical simulations of jet propagation. The BNS merger ejecta is prepared based on numerical relativity simulations of a BNS merger with the highest-resolution to date. We show that our analytic results agree with numerical simulations over a wide parameter space. Then we apply our analytic model to GW170817, and obtain two solid constraints on: i) the central engine luminosity as Liso, 0 ∼ 3 × 1049 − 2.5 × 1052 erg s−1, and on ii) the delay time between the merger and engine activation t0 − tm < 1.3 s. The engine power implies that the apparently-faint short gamma-ray burst (sGRB) sGRB 170817A is similar to typical sGRBs if observed on-axis.

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Prospects of joint detections of neutron star mergers and short GRBs with Gaussian structured jets

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa303 ◽

2020 ◽

Vol 493 (2) ◽

pp. 1633-1639

Author(s):

M Saleem

Keyword(s):

Neutron Star ◽

Joint Detection ◽

Detection Rates ◽

Binary Neutron Star ◽

The Core ◽

Relativistic Jet ◽

Inclination Angles ◽

Γ Ray ◽

Short Grbs ◽

Lower Inclination

ABSTRACT GW170817 was the first ever joint detection of gravitational waves (GW) from a binary neutron star (BNS) merger with the detections of short γ-ray burst (SGRB) counterparts. Analysis of the multiband afterglow observations of over more than a year revealed that the outflow from the merger end product was consistent with structured relativistic jet models with the core of the jet narrowly collimated to half-opening angles ∼5○. In this work, assuming that all the BNS mergers produce Gaussian structured jets with properties as inferred for GW170817, we explore the prospects of joint detections of BNS mergers and prompt γ-ray emission, expected during the current and upcoming upgrades of LIGO–Virgo–KAGRA detectors. We discuss three specific observational aspects: 1) the distribution of detected binary inclination angles, 2) the distance reach, and 3) the detection rates. Unlike GW-only detections, the joint detections are greatly restricted at large inclination angles, due to the structure of the jets. We find that at lower inclination angles (say below 20○), the distance reach as well as the detection rates of the joint detections are limited by GW detectability while at larger inclinations (say above 20○), they are limited by the γ-ray detectability.

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Inclination Estimates from Off-Axis GRB Afterglow Modelling

Universe ◽

10.3390/universe7090329 ◽

2021 ◽

Vol 7 (9) ◽

pp. 329

Author(s):

Gavin P. Lamb ◽

Joseph J. Fernández ◽

Fergus Hayes ◽

Albert K. H. Kong ◽

En-Tzu Lin ◽

...

Keyword(s):

Neutron Star ◽

Cosmological Parameters ◽

Hubble Constant ◽

Lateral Spreading ◽

Line Of Sight ◽

Temporal Behaviour ◽

Model Free ◽

Relativistic Jet ◽

Free Parameters ◽

Jet Structure

For gravitational wave (GW) detected neutron star mergers, one of the leading candidates for electromagnetic (EM) counterparts is the afterglow from an ultra-relativistic jet. Where this afterglow is observed, it will likely be viewed off-axis, such as the afterglow following GW170817/GRB 170817A. The temporal behaviour of an off-axis observed GRB afterglow can be used to reveal the lateral jet structure, and statistical model fits can put constraints on the various model free-parameters. Amongst these parameters is the inclination of the system to the line of sight. Along with the GW detection, the afterglow modelling provides the best constraint on the inclination to the line-of-sight and can improve the estimates of cosmological parameters, for example, the Hubble constant, from GW-EM events. However, modelling of the afterglow depends on the assumed jet structure and—often overlooked—the effects of lateral spreading. Here we show how the inclusion of lateral spreading in the afterglow models can affect the estimated inclination of GW-EM events.

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On the Energetics of a Possible Relativistic Jet Associated with the Binary Neutron Star Merger Candidate S190425z

The Astrophysical Journal ◽

10.3847/1538-4357/ab6731 ◽

2020 ◽

Vol 891 (2) ◽

pp. 130 ◽

Cited By ~ 1

Author(s):

M. Saleem ◽

L. Resmi ◽

K. G. Arun ◽

S. Mohan

Keyword(s):

Neutron Star ◽

Binary Neutron Star ◽

Relativistic Jet

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Compact radio emission indicates a structured jet was produced by a binary neutron star merger

Science ◽

10.1126/science.aau8815 ◽

2019 ◽

Vol 363 (6430) ◽

pp. 968-971 ◽

Cited By ~ 92

Author(s):

G. Ghirlanda ◽

O. S. Salafia ◽

Z. Paragi ◽

M. Giroletti ◽

J. Yang ◽

...

Keyword(s):

Neutron Star ◽

Very Long Baseline Interferometry ◽

High Spatial Resolution ◽

Apparent Size ◽

Source Size ◽

Global Network ◽

Binary Neutron Star ◽

Long Baseline ◽

Relativistic Jet ◽

Merger Event

The binary neutron star merger event GW170817 was detected through both electromagnetic radiation and gravitational waves. Its afterglow emission may have been produced by either a narrow relativistic jet or an isotropic outflow. High-spatial-resolution measurements of the source size and displacement can discriminate between these scenarios. We present very-long-baseline interferometry observations, performed 207.4 days after the merger by using a global network of 32 radio telescopes. The apparent source size is constrained to be smaller than 2.5 milli–arc seconds at the 90% confidence level. This excludes the isotropic outflow scenario, which would have produced a larger apparent size, indicating that GW170817 produced a structured relativistic jet. Our rate calculations show that at least 10% of neutron star mergers produce such a jet.

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