Illuminating gravitational waves: A concordant picture of photons from a neutron star merger

By Mansi M. Kasliwal, E. Nakar, L. Singer, D. Kaplan, D. Cook, A. Van Sistine, R. Lau, C. Fremling, O. Gottlieb, J. Jencson and 71 more. Science, 2017

626 citations recorded by the source corpus.

GROWTH observations of GW170817 The gravitational wave event GW170817 was caused by the merger of two neutron stars (see the Introduction by Smith). In three papers, teams associated with the GROWTH (Global Relay of Observatories Watching Transients Happen) project present their observations of the event at wavelengths from x-rays to radio waves. Evans et al. used space telescopes to detect GW170817 in the ultraviolet and place limits on its x-ray flux, showing that the merger generated a hot explosion known as a blue kilonova. Hallinan et al. describe radio emissions generated as the explosion slammed into the surrounding gas within the host galaxy. Kasliwal et al. present additional observations in the optical and infrared and formulate a model for the event involving a cocoon of material expanding at close to the speed of light, matching the data at all observed wavelengths. Science, this issue p. 1565, p. 1579, p. 1559; see also p. 1554 Observations of a binary neutron star merger at multiple wavelengths can be explained by an off-axis relativistic cocoon model. Merging neutron stars offer an excellent laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of an electromagnetic counterpart (EM170817) with gravitational waves (GW170817) detected from merging neutron stars. By synthesizing a panchromatic data set, we demonstrate that merging neutron stars are a long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma rays seen in EM170817 are dissimilar to classical short gamma-ray bursts with ultrarelativistic jets. Instead, we suggest that breakout of a wide-angle, mildly relativistic cocoon engulfing the jet explains the low-luminosity gamma rays, the high-luminosity ultraviolet-optical-infrared, and the delayed radio and x-ray emission. We posit that all neutron star mergers may lead to a wide-angle cocoon breakout, sometimes accompanied by a successful jet and sometimes by a choked jet.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

A Magnetar Origin for the Kilonova Ejecta in GW170817 (2018, background): “…thermal energy could be deposited into the expanding matter also by the passage of a relativistic jet through the blue ejecta, creating an expanding tail of high velocity shock-heated matter (e.g., Bromberg et al. 2017; Gottlieb et al. 2017, 2018; Kasliwal et al. 2017; Piro & Kollmeier 2017).”
Femtolensing by dark matter revisited (2018, background): “As discussed in [66], the observational data pertaining to this event across the electromagnetic spectrum are best described by a model in which a mildly relativistic wide-angle shock with Γ ∼ 2.”
A cocoon shock breakout as the origin of the γ-ray emission in GW170817 (2017, methodology): “The observations of the macronova accompanying GW170817 confirms this idea putting a lower limit of 0.02M on the mass ejected in this event (Kasliwal et al. 2017).”
The Binary Neutron Star Event LIGO/Virgo GW170817 160 Days after Merger: Synchrotron Emission across the Electromagnetic Spectrum (2018, methodology): “Mooley et al. (2017) (see also Salafia et al. 2017; Kasliwal et al. 2017; Hallinan et al. 2017; Nakar & Piran 2018) of emission from a quasi-isotropic mildly relativistic fireball with stratified ejecta and no surviving ultra-relativistic jet (i.e. their “choked jet cocoon" scenario), but do not…”
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, result): “…2017; Arcavi et al. 2017; Coulter 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…”
The fast, luminous ultraviolet transient AT2018cow: extreme supernova, or disruption of a star by an intermediate-mass black hole? (2018, background): “Furthermore, AT2018cow empirically bears no relation to the (much dimmer, fast-cooling, fast-expanding) optical counterpart of GW170817 (McCully et al. 2017; Kasliwal et al. 2017; Evans et al. 2017; Villar et al. 2017; Pian et al. 2017).”
Follow Up of GW170817 and Its Electromagnetic Counterpart by Australian-Led Observing Programmes (2017, background): “The optical transient is located at RA = 13:09:48.089 DEC = −23:22:53.350 (Adams et al. 2017; Kasliwal et al. 2017), approximately 2.2 kpc from the centre of its host galaxy NGC 4993.”
The Origin of r-process Elements in the Milky Way (2017, background): “For better agreement with observations, some studies argued that an additional third ejecta component is required, such as a wide-angle mildly relativistic cocoon (Kasliwal et al. 2017b), secular disk winds (Perego et al. 2017) or a “purple kilonova” outflow (Cowperthwaite et al. 2017).”
Constraining the Maximum Mass of Neutron Stars from Multi-messenger Observations of GW170817 (2017, background): “…Kasen 2013; Tanaka & Hotokezaka 2013) at late times requires at least two distinct ejecta components consisting, respectively, of light and heavy r-process nuclei (e.g. Cowperthwaite et al. 2017; Nicholl et al. 2017; Chornock et al. 2017; Kasen et al. 2017; Drout et al. 2017; Kasliwal et al. 2017).”
Constraints on the neutron star equation of state from AT2017gfo using radiative transfer simulations (2018, background): “Our approach was to (i) complement this photometry only when this was necessary either due to insufficient temporal or wavelength coverage, (ii) primarily use only grizyJHKS AB mag photometry from sources that used image subtraction (mostly DECam and Skymapper Cowperthwaite et al. 2017; Andreoni et ”
A Decline in the X-Ray through Radio Emission from GW170817 Continues to Support an Off-axis Structured Jet (2018, background): “…for the production of relativistic ejecta in such a system (Alexander et al. 2017; Granot et al. 2017; Haggard et al. 2017; Hallinan et al. 2017; Kasliwal et al. 2017; Margutti et al. 2017, 2018; Murguia-Berthier et al. 2017; Troja et al. 2017; Kathirgamaraju et al. 2018; Mooley et al. 2018b).”
Neutron-star Radius Constraints from GW170817 and Future Detections (2017, background): “…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 near the high end of…”