The multimessenger picture of compact object encounters: binary mergers versus dynamical collisions

By Stephan Rosswog, T. Piran, E. Nakar. 2012

175 citations recorded by the source corpus.

We explore the multi-messenger signatures of encounters between two neutron stars (ns 2 ) and between a neutron star and a stellar-mass black hole (nsbh). We focus on the dierences between gravitational wave driven binary mergers and dynamical collisions that occur, for example, in globular clusters. Our discussion is based on Newtonian hydrodynamics simulations that incorporate a nuclear equation of state and a multiavour neutrino treatment. For both types of encounters we compare the gravitational wave and neutrino emission properties. We also calculate the rates at which nearly unbound mass is delivered back to the central remnant in a ballistic-fallback-plusviscous-disk model and we analyze the properties of the dynamically ejected matter. Last but not least we address the electromagnetic transients that accompany each type of encounter. We nd that dynamical collisions are at least as promising as binary mergers for producing (short) gamma-ray bursts, but they also share the same possible caveats in terms of baryonic pollution. All encounter remnants produce peak neutrino luminosities of at least 10 53 erg/s, some of the collision cases exceed this value by more than an order of magnitude. The canonical ns 2 merger case ejects more than 1% of a solar mass of extremely neutron-rich (Ye 0:03) material, an amount that is consistent with double neutron star mergers being a major source of r-process in the galaxy. nsbh collisions eject very large amounts of matter ( 0:15 M ) which seriously constrains their admissible occurrence rates. The compact object collision rate (sum of ns 2 and nsbh) must therefore be less, likely much less, than 10% of the ns 2 merger rate. The radioactively decaying ejecta produce optical-UV \macronova" which, for the canonical merger case, peak after 0:4 days with a luminosity of 5 10 41 erg/s. ns 2 (nsbh) collisions reach up to 2 (4) times larger peak luminosities. The dynamic ejecta deposit a kinetic energy comparable to a supernova in the ambient medium. The canonical merger case releases approximately 2 10 50 erg, the most extreme (but likely rare) cases deposit kinetic energies of up to 10 52 erg. The deceleration of this mildly relativistic material by the ambient medium produces long lasting radio ares. A canonical ns 2 merger at the detection horizon of advanced LIGO/Virgo produces a radio

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Neutrino-driven winds from neutron star merger remnants (2014, background): “In the case of Newtonian simulations, the compatibility is good also from a quantitative point of view, usually within 25 per cent (see e.g. the values obtained in Rosswog et al. 2013, for the run H, to be compared with our cooling luminosities).”
THE FORMATION OF ECCENTRIC COMPACT BINARY INSPIRALS AND THE ROLE OF GRAVITATIONAL WAVE EMISSION IN BINARY–SINGLE STELLAR ENCOUNTERS (2013, background): “Merging binaries are expected to show environmental dependance in their electromagnetic signatures (Panaitescu et al. 2001; Rosswog & Ramirez-Ruiz 2002; Metzger & Berger 2012; Kelley et al. 2013; Rosswog et al. 2013).”
The long-term evolution of neutron star merger remnants – I. The impact of r-process nucleosynthesis (2013, methodology): “The simulations of this paper start from the final matter distributions of the runs presented in Rosswog et al. (2013) and Rosswog (2013).”
The Origin of r-process Elements in the Milky Way (2017, methodology): “…Estimates Instead of using GCE simulations and reproducing stellar abundances, analytical calculations can also be used to estimate the role of NS-NS mergers on the Galactic r-process enrichment (e.g., Metzger et al. 2010; Bauswein et al. 2013; Rosswog et al. 2013; Hotokezaka et al. 2015).”
Dynamical Mass Ejection from Binary Neutron Star Mergers (2016, methodology): “This trend is the opposite of what is found in Newtonian simulations by Rosswog et al. (2013), which found eccentric mergers to yield more proton-rich outflows than quasi-circular mergers.”
Binary Neutron Star Mergers: Mass Ejection, Electromagnetic Counterparts, and Nucleosynthesis (2018, methodology): “…most previous binary NS merger simulations either employed an approximate treatment for the gravitational field of the NSs (Ruffert et al. 1996; Rosswog et al. 1999, 2003, 2013; Rosswog & Davies 2003; Rosswog & Liebendoerfer 2003; Oechslin et al. 2007; Korobkin et al. 2012; Bauswein et al.…”
The physics of gamma-ray bursts & relativistic jets (2014, background): “Leading candidates include mergers (or for a small fraction, collisions) of NS-NS and NS-BH systems (Eichler et al., 1989; Paczýnski, 1991; Rosswog et al., 2013).”
BRIGHT “MERGER-NOVA” FROM THE REMNANT OF A NEUTRON STAR BINARY MERGER: A SIGNATURE OF A NEWLY BORN, MASSIVE, MILLISECOND MAGNETAR (2013, background): “Numerical simulations show that a more isotropic, sub-relativistic (vej ∼ 0.15−0.25c) outflow could be ejected during a merger, which could include the tidal tail matter during the merger and the matter from the accretion disk (e.g. Rezzolla et al. 2011; Bauswein et al. 2013; Rosswog et al. 2013).”
The long-term evolution of neutron star merger remnants { II. Radioactively powered transients (2013, methodology): “The simulations of this paper begin from the final configurations of calculations presented in Rosswog et al. (2013) and Rosswog (2013).”
Neutron-powered precursors of kilonovae (2014, background): “NS binary mergers thus represent promising astrophysical sites for creating the heaviest elements in the universe via rapid neutron capture nucleosynthesis (the r-process; e.g. Lattimer & Schramm 1974; Freiburghaus et al. 1999; Goriely et al. 2011; Rosswog et al. 2013).”
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Discovery of the Optical Counterpart Using the Dark Energy Camera (2017, background): “…observations provide critical insights into the astrophysics of the event, such as the progenitor environment, the formation of relativistic and non-relativistic outflows, and in some cases the nature of merger products (e.g., Metzger & Berger 2012; Rosswog et al. 2013; Baiotti & Rezzolla 2017).”
Delayed outflows from black hole accretion tori following neutron star binary coalescence (2013, background): “…the merger (Lattimer & Schramm 1974; Rosswog et al. 1999; Rosswog 2005; Chawla et al. 2010; Stephens et al. 2011; East et al. 2012; Rosswog 2012; Rosswog et al. 2013; Bauswein et al. 2013), and recent nuclear reaction network calculations largely agree on the amount of radioactive heating…”
Neutron Star Mergers Might Not Be the Only Source of r-process Elements in the Milky Way (2018, methodology): “To illustrate this, we have performed r-process calculations based on the NS-NS merger simulation of Rosswog et al. (2013) involving two neutron stars of 1.4 M each, and based on the MR SN model of Winteler et al. (2012) (see Figure 6).”