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

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.

2020 ◽  
Vol 29 (11) ◽  
pp. 2041015
Author(s):  
John L. Friedman ◽  
Nikolaos Stergioulas

The first inspiral of two neutron stars observed in gravitational waves was remarkably close, allowing the kind of simultaneous gravitational wave and electromagnetic observation that had not been expected for several years. Their merger, followed by a gamma-ray burst and a kilonova, was observed across the spectral bands of electromagnetic telescopes. These GW and electromagnetic observations have led to dramatic advances in understanding short gamma-ray bursts; determining the origin of the heaviest elements; and determining the maximum mass of neutron stars. From the imprint of tides on the gravitational waveforms and from observations of X-ray binaries, one can extract the radius and deformability of inspiraling neutron stars. Together, the radius, maximum mass, and causality constrain the neutron-star equation of state, and future constraints can come from observations of post-merger oscillations. We selectively review these results, filling in some of the physics with derivations and estimates.


Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 119 ◽  
Author(s):  
Antonios Nathanail

In the dawn of the multi-messenger era of gravitational wave astronomy, which was marked by the first ever coincident detection of gravitational waves and electromagnetic radiation, it is important to take a step back and consider our current established knowledge. Numerical simulations of binary neutron star mergers and simulations of short GRB jets must combine efforts to understand such complicated and phenomenologically rich explosions. We review the status of numerical relativity simulations with respect to any jet or magnetized outflow produced after merger. We compare what is known from such simulations with what is used and obtained from short GRB jet simulations propagating through the BNS ejecta. We then review the established facts on this topic, as well as discuss things that need to be revised and further clarified.


2018 ◽  
Vol 480 (3) ◽  
pp. 3871-3878 ◽  
Author(s):  
Michael W Coughlin ◽  
Tim Dietrich ◽  
Zoheyr Doctor ◽  
Daniel Kasen ◽  
Scott Coughlin ◽  
...  

ABSTRACT The detection of the binary neutron star merger GW170817 together with the observation of electromagnetic counterparts across the entire spectrum inaugurated a new era of multimessenger astronomy. In this study, we incorporate wavelength-dependent opacities and emissivities calculated from atomic-structure data enabling us to model both the measured light curves and spectra of the electromagnetic transient AT2017gfo. Best fits of the observational data are obtained by Gaussian Process Regression, which allows us to present posterior samples for the kilonova and source properties connected to GW170817. Incorporating constraints obtained from the gravitational wave signal measured by the LIGO-Virgo Scientific Collaboration, we present a $90{{\ \rm per\ cent}}$ upper bound on the mass ratio q ≲ 1.38 and a lower bound on the tidal deformability of $\tilde{\Lambda } \gtrsim 197$, which rules out sufficiently soft equations of state. Our analysis is a path-finder for more realistic kilonova models and shows how the combination of gravitational wave and electromagnetic measurements allow for stringent constraints on the source parameters and the supranuclear equation of state.


2016 ◽  
Vol 94 (6) ◽  
Author(s):  
Takumu Kawamura ◽  
Bruno Giacomazzo ◽  
Wolfgang Kastaun ◽  
Riccardo Ciolfi ◽  
Andrea Endrizzi ◽  
...  

2019 ◽  
pp. 138-145
Author(s):  
Nicholas Mee

The fourth gravitational wave signal detected by LIGO GW170817 coincided with a short gamma ray burst and these signals have been interpreted as the result of a binary neutron star merger. It is thought that gold and other heavy elements are produced in binary neutron star collisions and the GW170817 event has provided support for this idea. Further evidence that heavy elements are produced in extremely rare events such as binary neutron star mergers has been deduced from the scarcity of these elements in dwarf galaxies. The Reticulum II dwarf galaxy is an exceptional case that does contain heavy elements that might have been created in a single such event.


2019 ◽  
Vol 492 (3) ◽  
pp. 3904-3927 ◽  
Author(s):  
S Antier ◽  
S Agayeva ◽  
V Aivazyan ◽  
S Alishov ◽  
E Arbouch ◽  
...  

ABSTRACT We present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA). The network consists of 21 telescopes with both photometric and spectroscopic facilities. They are connected together thanks to a dedicated infrastructure. The network aims at coordinating the observations of large sky position estimates of transient events to enhance their follow-up and reduce the delay between the initial detection and optical confirmation. The GRANDMA programme mainly focuses on follow-up of gravitational-wave alerts to find and characterize the electromagnetic counterpart during the third observational campaign of the Advanced LIGO and Advanced Virgo detectors. But it allows for follow-up of any transient alerts involving neutrinos or gamma-ray bursts, even those with poor spatial localization. We present the different facilities, tools, and methods we developed for this network and show its efficiency using observations of LIGO/Virgo S190425z, a binary neutron star merger candidate. We furthermore report on all GRANDMA follow-up observations performed during the first six months of the LIGO–Virgo observational campaign, and we derive constraints on the kilonova properties assuming that the events’ locations were imaged by our telescopes.


2021 ◽  
Vol 502 (4) ◽  
pp. 4680-4688
Author(s):  
Ankan Sur ◽  
Brynmor Haskell

ABSTRACT In this paper, we study the spin-evolution and gravitational-wave luminosity of a newly born millisecond magnetar, formed either after the collapse of a massive star or after the merger of two neutron stars. In both cases, we consider the effect of fallback accretion; and consider the evolution of the system due to the different torques acting on the star, namely the spin-up torque due to accretion and spin-down torques due to magnetic dipole radiation, neutrino emission, and gravitational-wave emission linked to the formation of a ‘mountain’ on the accretion poles. Initially, the spin period is mostly affected by the dipole radiation, but at later times, accretion spin the star up rapidly. We find that a magnetar formed after the collapse of a massive star can accrete up to 1 M⊙, and survive on the order of 50 s before collapsing to a black hole. The gravitational-wave strain, for an object located at 1 Mpc, is hc ∼ 10−23 at kHz frequencies, making this a potential target for next-generation ground-based detectors. A magnetar formed after a binary neutron star merger, on the other hand, accretes at the most 0.2 M⊙ and emits gravitational waves with a lower maximum strain of the order of hc ∼ 10−24, but also survives for much longer times, and may possibly be associated with the X-ray plateau observed in the light curve of a number of short gamma-ray burst.


2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Rossella Gamba ◽  
Matteo Breschi ◽  
Sebastiano Bernuzzi ◽  
Michalis Agathos ◽  
Alessandro Nagar

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