scholarly journals Mergers of Binary Neutron Star Systems: A Multimessenger Revolution

2021 ◽  
Vol 7 ◽  
Author(s):  
Elena Pian
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Direct Detection ◽  
Radioactive Decay ◽  
High Energy ◽  
High Energy Astrophysics ◽  
Infrared Source ◽  
Binary Neutron Star ◽  
History Of

On August 17, 2017, less than two years after the direct detection of gravitational radiation from the merger of two∼30 M⊙ black holes, a binary neutron star merger was identified as the source of a gravitational wave signal of ∼100 s duration that occurred at less than 50 Mpc from Earth. A short gamma-ray burst was independently identified in the same sky area by the Fermi and INTEGRAL satellites for high energy astrophysics, which turned out to be associated with the gravitational event. Prompt follow-up observations at all wavelengths led first to the detection of an optical and infrared source located in the spheroidal Galaxy NGC4993 and, with a delay of ∼10 days, to the detection of radio and X-ray signals. This article revisits these observations and focusses on the early optical/infrared source, which was thermal in nature and powered by the radioactive decay of the unstable isotopes of elements synthesized via rapid neutron capture during the merger and in the phases immediately following it. The far-reaching consequences of this event for cosmic nucleosynthesis and for the history of heavy elements formation in the Universe are also illustrated.

scholarly journals Data-driven Expectations for Electromagnetic Counterpart Searches Based on LIGO/Virgo Public Alerts

2022 ◽  
Vol 924 (2) ◽  
pp. 54
Author(s):  
Polina Petrov ◽  
Leo P. Singer ◽  
Michael W. Coughlin ◽  
Vishwesh Kumar ◽  
Mouza Almualla ◽  
...  
Keyword(s):  
Data Analysis ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Data Driven ◽  
Wave Localization ◽  
Localization Accuracy ◽  
Binary Neutron Star ◽  
Data Release

Abstract Searches for electromagnetic counterparts of gravitational-wave signals have redoubled since the first detection in 2017 of a binary neutron star merger with a gamma-ray burst, optical/infrared kilonova, and panchromatic afterglow. Yet, one LIGO/Virgo observing run later, there has not yet been a second, secure identification of an electromagnetic counterpart. This is not surprising given that the localization uncertainties of events in LIGO and Virgo’s third observing run, O3, were much larger than predicted. We explain this by showing that improvements in data analysis that now allow LIGO/Virgo to detect weaker and hence more poorly localized events have increased the overall number of detections, of which well-localized, gold-plated events make up a smaller proportion overall. We present simulations of the next two LIGO/Virgo/KAGRA observing runs, O4 and O5, that are grounded in the statistics of O3 public alerts. To illustrate the significant impact that the updated predictions can have, we study the follow-up strategy for the Zwicky Transient Facility. Realistic and timely forecasting of gravitational-wave localization accuracy is paramount given the large commitments of telescope time and the need to prioritize which events are followed up. We include a data release of our simulated localizations as a public proposal planning resource for astronomers.

scholarly journals The afterglow and kilonova of the short GRB 160821B

2019 ◽  
Author(s):  
E Troja ◽  
A J Castro-Tirado ◽  
J Becerra González ◽  
Y Hu ◽  
G S Ryan ◽  
...  
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Surrounding Medium ◽  
Rapid Evolution ◽  
Radioactive Decay ◽  
Reverse Shock ◽  
Binary Neutron Star ◽  
Global Properties ◽  
Relativistic Jet ◽  
Low Mass

Abstract GRB 160821B is a short duration gamma-ray burst (GRB) detected and localized by the Neil Gehrels Swift Observatory in the outskirts of a spiral galaxy at z=0.1613, at a projected physical offset of ≈16 kpc from the galaxy’s center. We present X-ray, optical/nIR and radio observations of its counterpart and model them with two distinct components of emission: a standard afterglow, arising from the interaction of the relativistic jet with the surrounding medium, and a kilonova, powered by the radioactive decay of the sub-relativistic ejecta. Broadband modeling of the afterglow data reveals a weak reverse shock propagating backward into the jet, and a likely jet-break at ≈3.5 d. This is consistent with a structured jet seen slightly off-axis (θview ∼ θcore) while expanding into a low-density medium (n ≈ 10−3 cm−3). Analysis of the kilonova properties suggests a rapid evolution toward red colors, similar to AT2017gfo, and a low nIR luminosity, possibly due to the presence of a long-lived neutron star. The global properties of the environment, the inferred low mass (Mej ≲ 0.006 M⊙) and velocities (vej ≳ 0.05c) of lanthanide-rich ejecta are consistent with a binary neutron star merger progenitor.

scholarly journals The first six months of the Advanced LIGO’s and Advanced Virgo’s third observing run with GRANDMA

2019 ◽  
Vol 492 (3) ◽  
pp. 3904-3927 ◽  
Author(s):  
S Antier ◽  
S Agayeva ◽  
V Aivazyan ◽  
S Alishov ◽  
E Arbouch ◽  
...  
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Spatial Localization ◽  
Gamma Ray Bursts ◽  
Binary Neutron Star ◽  
The Third ◽  
Transient Events ◽  
Tools And Methods

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.

scholarly journals UVscope and its application aboard the ASTRI-Horn telescope

2021 ◽  
Author(s):  
Maria Concetta Maccarone ◽  
Giovanni La Rosa ◽  
Osvaldo Catalano ◽  
Salvo Giarrusso ◽  
Alberto Segreto ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Single Photon ◽  
Photon Counting ◽  
Light Flux ◽  
Cosmic Ray ◽  
High Energy ◽  
Wide Field ◽  
High Energy Astrophysics ◽  
Single Photon Counting ◽  
Photon Counting Mode

AbstractUVscope is an instrument, based on a multi-pixel photon detector, developed to support experimental activities for high-energy astrophysics and cosmic ray research. The instrument, working in single photon counting mode, is designed to directly measure light flux in the wavelengths range 300-650 nm. The instrument can be used in a wide field of applications where the knowledge of the nocturnal environmental luminosity is required. Currently, one UVscope instrument is allocated onto the external structure of the ASTRI-Horn Cherenkov telescope devoted to the gamma-ray astronomy at very high energies. Being co-aligned with the ASTRI-Horn camera axis, UVscope can measure the diffuse emission of the night sky background simultaneously with the ASTRI-Horn camera, without any interference with the main telescope data taking procedures. UVscope is properly calibrated and it is used as an independent reference instrument for test and diagnostic of the novel ASTRI-Horn telescope.

scholarly journals Multimessenger approaches to exploring dense matter in neutron stars

2021 ◽  
Author(s):  
◽  
Lukas Weih
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Nuclear Physics ◽  
Computational Cost ◽  
Dense Matter ◽  
High Energy ◽  
Radiative Transport ◽  
Binary Neutron Star ◽  
Starting Point ◽  
Numerical Astrophysics

High-energy astrophysics plays an increasingly important role in the understanding of our universe. On one hand, this is due to ground-breaking observations, like the gravitational-wave detections of the LIGO and Virgo network or the black-hole shadow observations of the EHT collaboration. On the other hand, the field of numerical relativity has reached a level of sophistication that allows for realistic simulations that include all four fundamental forces of nature. A prime example of how observations and theory complement each other can be seen in the studies following GW170817, the first detection of gravitational waves from a binary neutron-star merger. The same detection is also the chronological starting point of this Thesis. The plethora of information and constraints on nuclear physics derived from GW170817 in conjunction with theoretical computations will be presented in the first part of this Thesis. The second part goes beyond this detection and prepares for future observations when also the high-frequency postmerger signal will become detectable. Specifically, signatures of a quark-hadron phase transition are discussed and the specific case of a delayed phase transition is analyzed in detail. Finally, the third part of this Thesis focuses on the inclusion of radiative transport in numerical astrophysics. In the context of binary neutron-star mergers, radiation in the form of neutrinos is crucial for realistic long-term simulations. Two methods are introduced for treating radiation: the approximate state-of-the-art two-moment method (M1) and the recently developed radiative Lattice-Boltzmann method. The latter promises to be more accurate than M1 at a comparable computational cost. Given that most methods for radiative transport or either inaccurate or unfeasible, the derivation of this new method represents a novel and possibly paradigm-changing contribution to an accurate inclusion of radiation in numerical astrophysics.

scholarly journals Introduction

1980 ◽  
Vol 5 ◽  
pp. 621-622
Author(s):  
H. van der Laan
Keyword(s):  
Good Deal ◽  
High Energy ◽  
General Assembly ◽  
High Energy Astrophysics ◽  
Optical Techniques ◽  
X Ray ◽  
Tremendous Progress ◽  
New Material ◽  
General Secretary

In the summer of 1977 the IAU General Secretary requested proposals for Joint Discussions at the XVIIth General Assembly more than two years later. As President of Commission 40 I wrote to other Commission Presidents proposing a J.D. on Extragalactic High Energy Astrophysics. The motivation was as follows, and I quote from my July 22, 1977 letter:“With the current advances in radio and optical techniques and the tremendous progress to be expected from the satellites HEAO-A and HEAO-B, to be launched respectively in the summer of 1977 and 1978, there should be a good deal of new material on high energy astrophysical phenomena in the extragalactic domain by the time of the 1979 General Assembly. Some of this will be of great cosmological significance and all of it will be astrophysically interesting. It is clear that the X-ray satellite results will get a lot of optical and radio follow-up and it therefore seems appropriate that a Joint Discussion of that topic be arranged at that time.”

scholarly journals The Unsolved Problem of Stellar Origins

1996 ◽  
Vol 169 ◽  
pp. 533-549
Author(s):  
Charles J. Lada
Keyword(s):  
Twentieth Century ◽  
Science Fiction ◽  
High Energy Physics ◽  
Gamma Ray ◽  
High Energy ◽  
Giant Molecular Clouds ◽  
Observational Astronomy ◽  
History Of ◽  
Large Telescopes ◽  
The Universe

We now stand at the threshold of the 21st century having witnessed perhaps the greatest era of astronomical discovery in the history of mankind. During the twentieth century the subject of astronomy was revolutionized and completely transformed by technology and physics. Advances in technology that produced radio astronomy, infrared astronomy, UV, X and γ ray astronomy, large telescopes on the ground, in balloons, aircraft and space coupled with advances in nuclear, atomic and high energy physics forever changed the way in which the universe is viewed. Indeed, it is altogether likely that future historians of science will consider the twentieth century as the Golden Age of observational astronomy. As a measure of how far we have come in the last 100 years, recall that at the turn of this century the nature of spiral nebulae and of the Milky Way itself as an island universe were not yet revealed. The expansion of the universe and the microwave background were not yet discovered and exotic objects such as quasars, pulsars, gamma-ray bursters and black holes were not even envisioned by the most imaginative authors of science fiction. The interstellar medium, with its giant molecular clouds, magnetic fields and obscuring dust was unknown. Not even the nature of stars, these most fundamental objects of the astronomical universe, was understood.

scholarly journals Constraints on the circumburst environments of short gamma-ray bursts

2020 ◽  
Vol 495 (4) ◽  
pp. 4782-4799 ◽  
Author(s):  
Brendan O’Connor ◽  
Paz Beniamini ◽  
Chryssa Kouveliotou
Keyword(s):  
Gamma Ray ◽  
Galactic Halo ◽  
Gamma Ray Bursts ◽  
Light Curves ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Binary Neutron Star ◽  
Range Of Values ◽  
Short Grbs

ABSTRACT Observational follow up of well localized short gamma-ray bursts (SGRBs) has left $20\!-\!30{{\ \rm per\ cent}}$ of the population without a coincident host galaxy association to deep optical and NIR limits (≳26 mag). These SGRBs have been classified as observationally hostless due to their lack of strong host associations. It has been argued that these hostless SGRBs could be an indication of the large distances traversed by the binary neutron star system (due to natal kicks) between its formation and its merger (leading to an SGRB). The distances of GRBs from their host galaxies can be indirectly probed by the surrounding circumburst densities. We show that a lower limit on those densities can be obtained from early afterglow light curves. We find that ${\lesssim}16{{\ \rm per\ cent}}$ of short GRBs in our sample took place at densities ≲10−4 cm−3. These densities represent the expected range of values at distances greater than the host galaxy’s virial radii. We find that out of the five SGRBs in our sample that have been found to be observationally hostless, none are consistent with having occurred beyond the virial radius of their birth galaxies. This implies one of two scenarios. Either these observationally hostless SGRBs occurred outside of the half-light radius of their host galaxy, but well within the galactic halo, or in host galaxies at moderate to high redshifts (z ≳ 2) that were missed by follow-up observations.

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