Transient Events from Neutron Star Mergers

Li, Lixin; Paczyński, B.

doi:10.1086/311680

Cited by 1,301 publications

(1,340 citation statements)

References 14 publications

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“…In addition to the GRB beamed emission and its late more isotropic orphan afterglow, electromagnetic waves will be emitted quasi isotropically at different stages from material that is ejected during the merger. Most notable one is a macronova (also called kilonova), an opticalinfrared transient driven by the radioactive decay of the heavy nuclei synthesized in the ejecta (Li & Paczyński 1998;Metzger et al 2010;Kasen et al 2013;Grossman et al 2014). Recently, the Hubble Space Telescope detected a near infrared bump at 9 days after the Swift short GRB 130603B (Tanvir et al 2013;Berger et al 2013), which is consistent with the theoretical expectation of macronovae.…”

Section: Introductionsupporting

confidence: 74%

Mass ejection from neutron star mergers: different components and expected radio signals

Hotokezaka

Piran

2015

Monthly Notices of the Royal Astronomical Society

132

137

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In addition to producing a strong gravitational signal, a short gamma-ray burst (GRB), and a compact remnant, neutron star mergers eject significant masses at significant kinetic energies. This mass ejection takes place via dynamical mass ejection and a GRB jet but other processes have also been suggested: a shock-breakout material, a cocoon resulting from the interaction of the jet with other ejecta, and viscous and neutrino driven winds from the central remnant or the accretion disk. The different components of the ejected masses include up to a few percent of a solar mass, some of which is ejected at relativistic velocities. The interaction of these ejecta with the surrounding interstellar medium will produce a long lasting radio flare, in a similar way to GRB afterglows or to radio supernovae. The relative strength of the different signals depends strongly on the viewing angle. An observer along the jet axis or close to it will detect a strong signal at a few dozen days from the radio afterglow (or the orphan radio afterglow) produced by the highly relativistic GRB jet. For a generic observer at larger viewing angles, the dynamical ejecta, whose contribution peaks a year or so after the event, will generally dominate. Depending on the observed frequency and the external density, other components may also give rise to a significant contribution. We also compare these estimates with the radio signature of the short GRB 130603B. The radio flare from the dynamical ejecta might be detectable with the EVLA and the LOFAR for the higher range of external densities n 0.5cm −3 .

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Section: Introductionsupporting

confidence: 74%

Mass ejection from neutron star mergers: different components and expected radio signals

Hotokezaka

Piran

2015

Monthly Notices of the Royal Astronomical Society

132

137

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“…Electromagnetically, such mergers are also postulated to generate a relatively rapidly evolving optical/infrared transient-referred to as kilonova or macronova (e.g., Li & Paczyński 1998;Metzger et al 2010;Roberts et al 2011;Barnes & Kasen 2013;Kasen, Fernández, & Metzger 2015;Metzger et al 2015;Barnes et al 2016). The combination of an sGRB and kilonova is considered the 'smoking gun' signature of such mergers.…”

Section: Follow Up Of Gw170817 and Its Electromagnetic Counterpart Bymentioning

confidence: 99%

Follow Up of GW170817 and Its Electromagnetic Counterpart by Australian-Led Observing Programmes

Andreoni

Ackley

Cooke

et al. 2017

Publ. Astron. Soc. Aust.

184

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The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early-to late-time multi-wavelength observations, including optical imaging and spectroscopy, midinfrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (∼2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.

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“…Macronovae are radioactively powered transients that emerge from the decaying ejecta of compact object mergers [3]. In contrast to GRBs, they should be 'isotropic' in the sense that they are visible from all sides, although the ejecta distribution suggests a viewing angle dependence (see figs 1 and 2 in Piran et al [63]).…”

Section: (E) Electromagnetic Transientsmentioning

confidence: 99%

“…By estimating the rates of such encounters, they already noted that the accumulated amount of ejecta would be roughly comparable with the inventory of galactic rapid neutron capture ('r-process') elements. It is only more recently that the potential of the ejected material to produce electromagnetic (EM) transients has been appreciated [3][4][5][6][7][8][9][10]. EM transients from compact binary mergers are nowadays thought to be instrumental for maximizing the science returns from the advanced gravitational wave (GW) detector networks.…”

Section: Introductionmentioning

confidence: 99%

The dynamic ejecta of compact object mergers and eccentric collisions

Rosswog

2013

Phil. Trans. R. Soc. A.

101

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Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers produce indeed gamma-ray bursts there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties and therefore plays a different role for nucleosynthesis and for the electromagnetic transients that go along with compact object encounters. Here we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject $\sim 1$% of a solar mass of extremely neutron-rich material. The exact amount as well as the ejection velocity depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the "heavy" ($A>130$) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass and therefore cannot occur frequently without overproducing galactic r-process matter. We also discuss the electromagnetic transients that are powered by radioactive decays within the ejecta ("Macronovae"), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium.Comment: accepted in Philosophical Transactions A; references update

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Transient Events from Neutron Star Mergers

Cited by 1,301 publications

References 14 publications

Mass ejection from neutron star mergers: different components and expected radio signals

Mass ejection from neutron star mergers: different components and expected radio signals

Follow Up of GW170817 and Its Electromagnetic Counterpart by Australian-Led Observing Programmes

The dynamic ejecta of compact object mergers and eccentric collisions

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