scholarly journals Shock within a shock: revisiting the radio flares of NS merger ejecta and gamma-ray burst-supernovae

2020 ◽  
Vol 495 (4) ◽  
pp. 4981-4993 ◽  
Author(s):  
Ben Margalit ◽  
Tsvi Piran
Keyword(s):  
Gamma Ray ◽  
Ambient Medium ◽  
Symmetric Model ◽  
Late Time ◽  
Numerical Work ◽  
Gamma Ray Burst ◽  
Binary Neutron Star ◽  
Radio Transients ◽  
Spherically Symmetric Model ◽  
Radio Flare

ABSTRACT Fast ejecta expelled in binary neutron star (NS) mergers or energetic supernovae (SNe) should produce late-time synchrotron radio emission as the ejecta shocks into the surrounding ambient medium. Models for such radio flares typically assume the ejecta expands into an unperturbed interstellar medium (ISM). However, it is also well known that binary NS mergers and broad-lined Ic SNe Ic can harbour relativistic jetted outflows. In this work, we show that such jets shock the ambient ISM ahead of the ejecta, thus evacuating the medium into which the ejecta subsequently collides. Using an idealized spherically symmetric model, we illustrate that this inhibits the ejecta radio flare at early times $t \lt t_{\rm col} \approx 12 \, {\rm yr} \, (E_{\rm j}/10^{49} \, {\rm erg})^{1/3} (n/1 \, {\rm cm}^{-3})^{-1/3} (\upsilon _{\rm ej}/0.1c)^{-5/3}$, where Ej is the jet energy, n the ISM density, and $\upsilon$ej the ejecta velocity. We also show that this can produce a sharply peaked enhancement in the light curve at t = tcol. This has implications for radio observations of GW170817 and future binary NS mergers, gamma-ray burst (GRB) SNe, decade-long radio transients such as FIRST J1419, and possibly other events where a relativistic outflow precedes a slower moving ejecta. Future numerical work will extend these analytic estimates and treat the multidimensional nature of the problem.

scholarly journals GRB 090926A AND BRIGHT LATE-TIME FERMI LARGE AREA TELESCOPE GAMMA-RAY BURST AFTERGLOWS

2010 ◽  
Vol 718 (1) ◽  
pp. L14-L18 ◽  
Author(s):  
C. A. Swenson ◽  
A. Maxham ◽  
P. W. A. Roming ◽  
P. Schady ◽  
L. Vetere ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Late Time ◽  
Large Area ◽  
Gamma Ray Burst

scholarly journals Low-Γ jets from Compact Binary Mergers as Candidate Electromagnetic Counterparts to Gravitational Wave Sources

2016 ◽  
Vol 12 (S324) ◽  
pp. 66-69
Author(s):  
Gavin P. Lamb ◽  
Shiho Kobayashi
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Radioactive Decay ◽  
Prompt Gamma ◽  
Late Time ◽  
Astrophysical Jets ◽  
Power Law Distribution ◽  
Compact Binary ◽  
Binary Mergers

AbstractCompact binary mergers, with neutron stars or neutron star and black-hole components, are thought to produce various electromagnetic counterparts: short gamma-ray bursts (GRBs) from ultra-relativistic jets followed by broadband afterglow; semi-isotropic kilonova from radioactive decay of r-process elements; and late time radio flares; etc. If the jets from such mergers follow a similar power-law distribution of Lorentz factors as other astrophysical jets then the population of merger jets will be dominated by low-Γ values. The prompt gamma-rays associated with short GRBs would be suppressed for a low-Γ jet and the jet energy will be released as X-ray/optical/radio transients when a shock forms in the ambient medium. Using Monte Carlo simulations, we study the properties of such transients as candidate electromagnetic counterparts to gravitational wave sources detectable by LIGO/Virgo. Approximately 78% of merger-jets result in failed GRB with optical peaks 14-22 magnitude and an all-sky rate of 2-3 per year.

scholarly journals GRB 030329: 3 years of radio afterglow monitoring

2007 ◽  
Vol 365 (1854) ◽  
pp. 1241-1246 ◽  
Author(s):  
A.J van der Horst ◽  
A Kamble ◽  
R.A.M.J Wijers ◽  
L Resmi ◽  
D Bhattacharya ◽  
...  
Keyword(s):  
Blast Wave ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Low Frequency ◽  
Blast Waves ◽  
Physical Parameters ◽  
Late Time ◽  
Wave Band ◽  
Radio Telescopes ◽  
Relativistic Phase

Radio observations of gamma-ray burst (GRB) afterglows are essential for our understanding of the physics of relativistic blast waves, as they enable us to follow the evolution of GRB explosions much longer than the afterglows in any other wave band. We have performed a 3-year monitoring campaign of GRB 030329 with the Westerbork Synthesis Radio Telescopes and the Giant Metrewave Radio Telescope. Our observations, combined with observations at other wavelengths, have allowed us to determine the GRB blast wave physical parameters, such as the total burst energy and the ambient medium density, as well as to investigate the jet nature of the relativistic outflow. Further, by modelling the late-time radio light curve of GRB 030329, we predict that the Low-Frequency Array (30–240 MHz) will be able to observe afterglows of similar GRBs, and constrain the physics of the blast wave during its non-relativistic phase.

scholarly journals NECESSARY CONDITIONS FOR SHORT GAMMA-RAY BURST PRODUCTION IN BINARY NEUTRON STAR MERGERS

2014 ◽  
Vol 788 (1) ◽  
pp. L8 ◽  
Author(s):  
Ariadna Murguia-Berthier ◽  
Gabriela Montes ◽  
Enrico Ramirez-Ruiz ◽  
Fabio De Colle ◽  
William H. Lee
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Necessary Conditions ◽  
Gamma Ray Burst ◽  
Binary Neutron Star

scholarly journals Late-time Evolution and Modeling of the Off-axis Gamma-Ray Burst Candidate FIRST J141918.9+394036

2022 ◽  
Vol 924 (1) ◽  
pp. 16
Author(s):  
K. P. Mooley ◽  
B. Margalit ◽  
C. J. Law ◽  
D. A. Perley ◽  
A. T. Deller ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Optical Data ◽  
Host Galaxy ◽  
Opening Angle ◽  
Late Time ◽  
Gamma Ray Burst ◽  
Very Large Array ◽  
Long Baseline ◽  
New Radio ◽  
Low Metallicity

Abstract We present new radio and optical data, including very-long-baseline interferometry, as well as archival data analysis, for the luminous, decades-long radio transient FIRST J141918.9+394036. The radio data reveal a synchrotron self-absorption peak around 0.3 GHz and a radius of around 1.3 mas (0.5 pc) 26 yr post-discovery, indicating a blastwave energy ∼5 × 1050 erg. The optical spectrum shows a broad [O iii]λ4959,5007 emission line that may indicate collisional excitation in the host galaxy, but its association with the transient cannot be ruled out. The properties of the host galaxy are suggestive of a massive stellar progenitor that formed at low metallicity. Based on the radio light curve, blastwave velocity, energetics, nature of the host galaxy and transient rates, we find that the properties of J1419+3940 are most consistent with long gamma-ray burst (LGRB) afterglows. Other classes of (optically discovered) stellar explosions as well as neutron star mergers are disfavored, and invoking any exotic scenario may not be necessary. It is therefore likely that J1419+3940 is an off-axis LGRB afterglow (as suggested by Law et al. and Marcote et al.), and under this premise the inverse beaming fraction is found to be f b − 1 ≃ 280 − 200 + 700 , corresponding to an average jet half-opening angle < θ j > ≃ 5 − 2 + 4 degrees (68% confidence), consistent with previous estimates. From the volumetric rate we predict that surveys with the Very Large Array, Australian Square Kilometre Array Pathfinder, and MeerKAT will find a handful of J1419+3940-like events over the coming years.

Anatomy of a merger

2019 ◽  
pp. 541-580
Author(s):  
Nils Andersson
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Binary System ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Late Time ◽  
Tidal Effects ◽  
Gamma Ray Burst ◽  
Love Numbers ◽  
Star Binary

This chapter discusses the different stages of an inspiralling neutron star binary system, through the formation of a black hole and the possible emergence of a gamma-ray burst. Tidal effects and the information encoded in the so-called Love numbers are explored. The violent dynamics of the merger is considered and models of gamma-ray bursts and the late time kilonova emission are also explored.

scholarly journals Protomagnetar research through an analysis of the X-ray plateau in the multi-messengar era

2020 ◽  
Vol 641 ◽  
pp. A56
Author(s):  
Xiaoxiao Ren ◽  
Daming Wei ◽  
Zhenyu Zhu ◽  
Yan Yan ◽  
Chengming Li
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Equations Of State ◽  
Electromagnetic Emission ◽  
Gamma Ray Bursts ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Binary Neutron Star

The joint detection of the gravitational wave signal and the electromagnetic emission from a binary neutron star merger can place unprecedented constraint on the equation of state of supranuclear matter. Although a variety of electromagnetic counterparts have been observed for GW170817, including a short gamma-ray burst, kilonova, and the afterglow emission, the nature of the merger remnant is still unclear, however. The X-ray plateau is another important characteristics of short gamma-ray bursts. This plateau is probably due to the energy injection from a rapidly rotating magnetar. We investigate what we can learn from the detection of a gravitational wave along with the X-ray plateau. In principle, we can estimate the mass of the merger remnant if the X-ray plateau is caused by the central magnetar. We selected eight equations of state that all satisfy the constraint given by the gravitational wave observation, and then calculated the mass of the merger remnants of four short gamma-ray bursts with a well-measured X-ray plateau. If, on the other hand, the mass of the merger remnant can be obtained by gravitational wave information, then by comparing the masses derived by these two different methods can further constrain the equation of state. We discuss the possibility that the merger product is a quark star. In addition, we estimate the possible mass range for the recently discovered X-ray transient CDF-S XT2 that probably originated from a binary neutron star merger. Finally, under the assumption that the post-merger remnant of GW170817 was a supramassive neutron star, we estimated the allowed parameter space of the supramassive neutron star and find that in this case, the magnetic dipole radiation energy is so high that it may have some effects on the short gamma-ray burst and kilonova emission. The lack of detection of these effects suggests that the merger product of GW170817 may not be a supermassive neutron star.

scholarly journals Jet propagation in expanding medium for gamma-ray bursts

2020 ◽  
Vol 500 (1) ◽  
pp. 627-642
Author(s):  
Hamid Hamidani ◽  
Kunihito Ioka
Keyword(s):  
Numerical Simulations ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Gamma Ray Bursts ◽  
Analytical Models ◽  
Opening Angle ◽  
Binary Neutron Star ◽  
Merger Event ◽  
Lateral Width ◽  
Jet Collimation

ABSTRACT The binary neutron star (BNS) merger event GW170817 clearly shows that a BNS merger launches a short gamma-ray burst (sGRB) jet. Unlike collapsars, where the ambient medium is static, in BNS mergers the jet propagates through the merger ejecta that is expanding outward at substantial velocities (∼0.2c). Here, we present semi-analytical and analytical models to solve the propagation of GRB jets through their surrounding media. These models improve our previous model by including the jet collimation by the cocoon self-consistently. We also perform a series of 2D numerical simulations of jet propagation in BNS mergers and in collapsars to test our models. Our models are consistent with numerical simulations in every aspect (the jet head radius, the cocoon’s lateral width, the jet opening angle including collimation, the cocoon pressure, and the jet–cocoon morphology). The energy composition of the cocoon is found to be different depending on whether the ambient medium is expanding or not; in the case of BNS merger jets, the cocoon energy is dominated by kinetic energy, while it is dominated by internal energy in collapsars. Our model will be useful for estimating electromagnetic counterparts to gravitational waves.

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