A kilonova as the electromagnetic counterpart to a gravitational-wave source

By S. Smartt, T.-W. Chen, A. Jerkstrand, M. Coughlin, E. Kankare, S. Sim, Morgan Fraser, C. Inserra, K. Maguire, K. Chambers and 112 more. Nature, 2017

643 citations recorded by the source corpus.

Gravitational waves were discovered with the detection of binary black-hole mergers and they should also be detectable from lower-mass neutron-star mergers. These are predicted to eject material rich in heavy radioactive isotopes that can power an electromagnetic signal. This signal is luminous at optical and infrared wavelengths and is called a kilonova. The gravitational-wave source GW170817 arose from a binary neutron-star merger in the nearby Universe with a relatively well confined sky position and distance estimate. Here we report observations and physical modelling of a rapidly fading electromagnetic transient in the galaxy NGC 4993, which is spatially coincident with GW170817 and with a weak, short γ-ray burst. The transient has physical parameters that broadly match the theoretical predictions of blue kilonovae from neutron-star mergers. The emitted electromagnetic radiation can be explained with an ejected mass of 0.04 ± 0.01 solar masses, with an opacity of less than 0.5 square centimetres per gram, at a velocity of 0.2 ± 0.1 times light speed. The power source is constrained to have a power-law slope of −1.2 ± 0.3, consistent with radioactive powering from r-process nuclides. (The r-process is a series of neutron capture reactions that synthesise many of the elements heavier than iron.) We identify line features in the spectra that are consistent with light r-process elements (atomic masses of 90–140). As it fades, the transient rapidly becomes red, and a higher-opacity, lanthanide-rich ejecta component may contribute to the emission. This indicates that neutron-star mergers produce gravitational waves and radioactively powered kilonovae, and are a nucleosynthetic source of the r-process elements.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/8a5545c3f443308d20e4995f7d8218406b34b21e

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In Astronomy and Astrophysics

1. B. Metzger
2. E. Berger
3. Bing Zhang
4. E. Quataert
5. D. Kasen
6. David Radice
7. T. Thompson
8. Luke F. Roberts

Citations in the corpus

• Science case for the Einstein telescope (2019, background): “of the heaviest elements through r-process nucleosynthesis [12–15]; the observation of tens of BH-BH coalescences has revealed a previously unknown population of stellar-mass BHs, much heavier than those detected through the observation of X-ray binaries [16], and has shown that BH-BH binaries exist”
• The Combined Ultraviolet, Optical, and Near-infrared Light Curves of the Kilonova Associated with the Binary Neutron Star Merger GW170817: Unified Data Set, Analytic Models, and Physical Implications (2017, methodology): “…et al. 2017; Cowperthwaite et al. 2017; Díaz et al. 2017; Drout et al. 2017; Evans et al. 2017; Hu et al. 2017; Kasliwal et al. 2017; Lipunov et al. 2017; Pian et al. 2017; Pozanenko et al. 2017; Smartt et al. 2017; Tanvir et al. 2017; Troja et al. 2017; Utsumi et al. 2017; Valenti et al. 2017b).”
• The Cow: Discovery of a Luminous, Hot, and Rapidly Evolving Transient (2018, background): “This lies in between the Mej of the kilonova, AT2017gfo (Mej = 0.04±0.01 M ; Smartt et al. 2017; Drout et al. 2017) and low-mass strippedenvelope core-collapse events such as SN 1994I (Mej ∼ 1 M ; Nomoto et al. 1994).”
• ATLAS: A High-cadence All-sky Survey System (2018, background): “ATLAS had been continually observing NGC4993 until 16 days before GW170817, and we showed it was not a variable source over the previous 601 days (Smartt et al. 2017, see also Valenti et al. 2017).”
• Progenitors of gravitational wave mergers: binary evolution with the stellar grid-based code ComBinE (2018, methodology): “…event, the loudest GW signal ever recorded with a S/N ratio of 32.4, was also detected as a sGRB (Fermi-LAT Collaboration 2017; Abbott et al. 2017e) and a multiwavelength kilonova (e.g. Soares-Santos et al. 2017; Coulter et al. 2017; Abbott et al. 2017d; Smartt et al. 2017; Drout et al. 2017).”
• The evolution of the X-ray afterglow emission of GW 170817 / GRB 170817A in XMM-Newton observations (2018, background): “…Li & Paczyński 1998), providing the first compelling observational evidence for the existence of such elusive transient sources (Cowperthwaite et al. 2017; Drout et al. 2017; Evans et al. 2017; Kasliwal et al. 2017; Nicholl et al. 2017; Pian et al. 2017; Smartt et al. 2017; Villar et al. 2017).”
• A Magnetar Origin for the Kilonova Ejecta in GW170817 (2018, background): “…of only ≈40Mpc (Abbott et al. 2017c; Arcavi et al. 2017; Coulter et al. 2017; Covino et al. 2017; Díaz 2017; Drout et al. 2017; Evans et al. 2017; Hu et al. 2017; Kilpatrick et al. 2017; McCully et al. 2017; Smartt et al. 2017; Soares-Santos et al. 2017; Utsumi et al. 2017; Buckley et al. 2018).”
• GW170817: Joint Constraint on the Neutron Star Equation of State from Multimessenger Observations (2017, background): “…al. 2017; Coulter et al. 2017; Cowperthwaite et al. 2017; Drout et al. 2017; Evans et al. 2017; Hallinan et al. 2017; Kasliwal et al. 2017; Murguia-Berthier et al. 2017; Nicholl et al. 2017; Smartt et al. 2017; Soares-Santos et al. 2017; Tanaka et al. 2017; Tanvir et al. 2017; Troja et al. 2017).”
• Constraints on the neutron star equation of state from AT2017gfo using radiative transfer simulations (2018, methodology): “We began with the photometry of Smartt et al. (2017) as the core data set and employed difference imaging at all epochs of PESSTO (Public ESO Spectroscopic Survey of Transient Objects; Smartt et al. 2015), GROND, and Pan-STARRS imaging.”
• Mass Ejection from the Remnant of a Binary Neutron Star Merger: Viscous-radiation Hydrodynamics Study (2017, background): “…simultaneously with GW170817(e.g., Abbott et al. 2017b; Arcavi et al. 2017; Coulter et al. 2017; Cowperthwaite et al. 2017; Drout et al. 2017; Kasliwal et al. 2017; Nicholl et al. 2017; Pian et al. 2017; Shappee et al. 2017; Smartt et al. 2017; Soares-Santos et al. 2017; Tanaka et al. 2017).”
• Binary Neutron Star Mergers: Mass Ejection, Electromagnetic Counterparts, and Nucleosynthesis (2018, background): “The peak times, magnitudes, and widths of AT2017gfo are obtained from Villar et al. (2017), Coulter et al. (2017), Smartt et al. (2017), and Tanvir et al. (2017).”
• Neutron-star Radius Constraints from GW170817 and Future Detections (2017, background): “…mass is in the range 0.03 to 0.05 M (Cowperthwaite et al. 2017; Kasen et al. 2017; Nicholl et al. 2017; Chornock et al. 2017; Drout et al. 2017; Smartt et al. 2017; Kasliwal et al. 2017; Kilpatrick et al. 2017; Tanvir et al. 2017; Tanaka et al. 2017), which even for asymmetric binaries lies…”
• The Binary Neutron Star Event LIGO/Virgo GW170817 160 Days after Merger: Synchrotron Emission across the Electromagnetic Spectrum (2018, background): “…Chornock et al. 2017; Coulter et al. 2017; Cowperthwaite et al. 2017; Drout et al. 2017; Kasliwal et al. 2017; Nicholl et al. 2017; Pian et al. 2017; Smartt et al. 2017; Soares-Santos et al. 2017; Tanvir et al. 2017; Valenti et al. 2017; Villar et al. 2017) and nonthermal synchrotron emission…”