WHAT IS THE MOST PROMISING ELECTROMAGNETIC COUNTERPART OF A NEUTRON STAR BINARY MERGER?

By B. Metzger, E. Berger. 2011

418 citations recorded by the source corpus.

The final inspiral of double neutron star and neutron-star–black-hole binaries are likely to be detected by advanced networks of ground-based gravitational wave (GW) interferometers. Maximizing the science returns from such a discovery will require the identification of an electromagnetic counterpart. Here we critically evaluate and compare several possible counterparts, including short-duration gamma-ray bursts (SGRBs), “orphan” optical and radio afterglows, and day-long optical transients powered by the radioactive decay of heavy nuclei synthesized in the merger ejecta (“kilonovae”). We assess the promise of each counterpart in terms of four “Cardinal Virtues”: detectability, high fraction, identifiability, and positional accuracy. Taking into account the search strategy for typical error regions of tens of square degrees, we conclude that SGRBs are the most useful to confirm the cosmic origin of a few GW events, and to test the association with neutron star mergers. However, for the more ambitious goal of localizing and obtaining redshifts for a large sample of GW events, kilonovae are instead preferred. Off-axis optical afterglows are detectable for at most tens of percent of events, while radio afterglows are promising only for energetic relativistic ejecta in a high-density medium. Our main recommendations are: (1) an all-sky gamma-ray satellite is essential for temporal coincidence detections, and for GW searches of gamma-ray-triggered events; (2) the Large Synoptic Survey Telescope should adopt a one-day cadence follow-up strategy, ideally with 0.5 hr per pointing to cover GW error regions; and (3) radio searches should focus on the relativistic case, which requires observations for a few months.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/58c83546df4bbd2091011184b3e149a76d19cbee

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In Astronomy and Astrophysics

1. B. Metzger
2. Bing Zhang
3. E. Berger
4. P. Hopkins
5. L. Hernquist
6. E. Quataert
7. D. Schneider
8. Volker Springel

Citations in the corpus

• The long-term evolution of neutron star merger remnants – I. The impact of r-process nucleosynthesis (2013, background): “…electromagnetic transients powered by radioactivity, so-called ‘macronovae’ (Li & Paczyński 1998; Kulkarni 2005; Rosswog 2005; Metzger et al. 2010; Roberts et al. 2011; Goriely et al. 2011a; Metzger & Berger 2012; Kelley et al. 2012; Rosswog et al. 2013; Piran et al. 2013; Barnes & Kasen 2013).”
• Multi-messenger observations of a binary neutron star merger (2017, background): “Despite these strong hints, proof that sGRBs were powered by neutron star mergers remained elusive, and interest intensified in following up gravitational-wave detections electromagnetically(Metzger & Berger 2012; Nissanke et al. 2013).”
• LSST: From Science Drivers to Reference Design and Anticipated Data Products (2008, background): “LSST’s unique ability to characterize the faint variable sky over large areas will be important not only for detection of associated sources but for eliminating potential false positives (Nissanke, Kasliwal & Georgieva 2013; Metzger & Berger 2012).”
• The Origin of r-process Elements in the Milky Way (2017, background): “…which are distinguished by the time of ejection: dynamical ejecta, generated at the time of contact, and everything else which emerges after the single object is formed, broadly referred to as “wind” ejecta either from a disk or a hypermassive neutron star (Metzger & Berger 2012; Metzger 2017).”
• AN r-PROCESS KILONOVA ASSOCIATED WITH THE SHORT-HARD GRB 130603B (2013, background): “Despite their low luminosity and fast timescale, kilonovae are of great interest as a detectable and isotropic counterpart to gravitation l wave sources from the upcoming Advanced LIGO/Virgo experiments (e.g., Metzger & Berger 2012).”
• OPACITIES AND SPECTRA OF THE r-PROCESS EJECTA FROM NEUTRON STAR MERGERS (2013, background): “…wave sources; if discovered coincidently, they could enhance the scientific value of an advanced LIGO/VIRGO gravitational wave signal (Schutz 1986; Kochanek & Piran 1993; Sylvestre 2003; Phinney 2009; Mandel & O’Shaughnessy 2010; Metzger & Berger 2012; Kelley et al. 2012; Nissanke et al. 2012).”
• SYSTEMATICS OF DYNAMICAL MASS EJECTION, NUCLEOSYNTHESIS, AND RADIOACTIVELY POWERED ELECTROMAGNETIC SIGNALS FROM NEUTRON-STAR MERGERS (2013, background): “…the Palomar Transient Factory, the Synoptic All Sky InfraRed Survey, the Panoramic Survey Telescope and Rapid Response System, and the Large Synoptic Survey Telescope (see e.g. Strubbe & Quataert (2009) and Metzger & Berger (2012) for a compilation of certain characteristics of these facilities).”
• Impact of ejecta morphology and composition on the electromagnetic signatures of neutron star mergers (2017, background): “Detection of electromagnetic counterparts would provide crucial information to localize the astrophysical environments of gravitational wave signals (Metzger & Berger 2012; Nissanke et al. 2013; Piran et al. 2013; Singer et al. 2014; Chu et al. 2015; Ghosh et al. 2015; Bartos et al. 2016; Abbott et…”
• Cosmological Fast Radio Bursts from Binary Neutron Star Mergers (2013, background): “Electromagnetic (EM) wave signatures from NS-NS mergers have been widely investigated in the literature (e.g., Metzger & Berger 2012).”
• Neutron-powered precursors of kilonovae (2014, background): “Kilonovae also represent a promising electromagnetic counterpart to the GW source (Metzger & Berger 2012).”
• EFFECT OF A HIGH OPACITY ON THE LIGHT CURVES OF RADIOACTIVELY POWERED TRANSIENTS FROM COMPACT OBJECT MERGERS (2013, background): “Metzger & Berger (2012) consider several possible EM transients associated with compact object mergers – short-duration gamma ray bursts, orphan radio and optical afterglows, and optical “kilonovae” light curves – and conclude that the last of these offers perhaps the best opportunity for…”
• Red or blue? A potential kilonova imprint of the delay until black hole formation following a neutron star merger (2014, background): “…by guest on 30 July 2018 Fortunately, NSMs are also accompanied by coincident electromagnetic (EM) signals that inform physical processes at work during the merger (e.g. Metzger & Berger 2012; Kelley, Mandel & Ramirez-Ruiz 2013; Piran, Nakar & Rosswog 2013).”
• Gravitational lensing of gravitational waves: A statistical perspective (2018, background): “These sources are especially intriguing in multimessenger observations, as these systems are believed to be associated with kilonovae and can produce electromagnetic counterparts (see e.g. Metzger & Berger 2012, for a theoretical study and Abbott et al. 2017e for a real observation).”
• On the astrophysical robustness of the neutron star merger r-process (2012, background): “…merger, but also the r-process nucleosynthesis and the decay of the resulting radioactive nuclei may leave an observable signature as optical/UV transients, so-called “macronovae” (Li & Paczyński 1998; Kulkarni 2005; Rosswog 2005; Metzger et al. 2010; Roberts et al. 2011; Metzger & Berger 2012).”
• Delayed outflows from black hole accretion tori following neutron star binary coalescence (2013, background): “The sky localization provided by initial Advanced LIGO/Virgo will be tens to hundreds of square degrees (e.g. Fairhurst 2009; Wen & Chen 2010; Nissanke et al. 2011), but a coincident X-ray, optical, or radio signal could provide a much more accurate position, such that the host galaxy and redshift o”
• Dynamical Mass Ejection from Binary Neutron Star Mergers (2016, background): “This makes BNS and BHNS mergers ideal candidates for multi-messenger astronomy (Metzger & Berger 2012; Nissanke et al. 2013) and motivates the systematic study of their observational signatures.”