The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. V. Rising X-Ray Emission from an Off-axis Jet

By Raffaella Margutti, E. Berger, W. Fong, C. Guidorzi, K. Alexander, B. Metzger, P. Blanchard, P. Cowperthwaite, Ryan Chornock, T. Efterkari and 11 more. 2017

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We report the discovery of rising X-ray emission from the binary neutron star merger event GW170817. This is the first detection of X-ray emission from a gravitational-wave (GW) source. Observations acquired with the Chandra X-ray Observatory (CXO) at t ≈ 2.3 days post-merger reveal no significant emission, with L x ≲ 3.2 × 10 38 erg s − 1 (isotropic-equivalent). Continued monitoring revealed the presence of an X-ray source that brightened with time, reaching L x ≈ 9 × 10 38 erg s − 1 at ≈ 15.1 days post-merger. We interpret these findings in the context of isotropic and collimated relativistic outflows (both on- and off-axis). We find that the broadband X-ray to radio observations are consistent with emission from a relativistic jet with kinetic energy E k ∼ 10 49 − 50 erg , viewed off-axis with θ obs ∼ 20 ° – 40 ° . Our models favor a circumbinary density n ∼ 10 − 4 – 10 − 2 cm − 3 , depending on the value of the microphysical parameter ϵ B = 10 − 4 – 10 − 2 . A central-engine origin of the X-ray emission is unlikely. Future X-ray observations at t ≳ 100 days, when the target will be observable again with the CXO, will provide additional constraints to solve the model degeneracies and test our predictions. Our inferences on θ obs are testable with GW information on GW170817 from advanced LIGO/Virgo on the binary inclination.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/7aba754d84b84d1ac47889b987aa48ab764467bc

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In Astronomy and Astrophysics

1. B. Metzger
2. E. Berger
3. Bing Zhang
4. E. Quataert
5. Michela Mapelli
6. N. Giacobbo
7. T. Thompson
8. D. Kasen

Citations in the corpus

• Constraining the Maximum Mass of Neutron Stars from Multi-messenger Observations of GW170817 (2017, background): “The delayed rise of synchrotron X-ray and radio emission is consistent with the afterglow from a much more powerful relativistic jet pointed away from our line of sight (Troja et al. 2017; Hallinan et al. 2017; Margutti et al. 2017; Alexander et al. 2017; Evans et al. 2017; Haggard et al. 2017).”
• Constraints on the neutron star equation of state from AT2017gfo using radiative transfer simulations (2018, background): “…et al. 2017; Drout et al. 2017; Evans et al. 2017; Haggard et al. 2017; Hallinan et al. 2017; Kasliwal et al. 2017; Kilpatrick et al. 2017; Margutti et al. 2017; McCully et al. 2017; Nicholl et al. 2017; Pian et al. 2017a; Shappee et al. 2017; Smartt et al. 2017; Troja et al. 2017; Utsumi…”
• The Binary Neutron Star Event LIGO/Virgo GW170817 160 Days after Merger: Synchrotron Emission across the Electromagnetic Spectrum (2018, methodology): “Further CXO observations obtained at δt ≈ 9d (Troja et al. 2017b, observation ID 19294; PI: Troja; Program 18500489) and δt ≈ 15d (Haggard et al. 2017; Margutti et al. 2017a; Troja et al. 2017b, observation IDs 18988, 20728; PIs: Haggard, Troja; Programs 18400410,18508587) since merger revealed…”
• Binary Neutron Star Mergers: Mass Ejection, Electromagnetic Counterparts, and Nucleosynthesis (2018, background): “A synchrotron remnant has been detected in X-ray, optical, and radio bands for GW170817 (Haggard et al. 2017; Hallinan et al. 2017; Margutti et al. 2017, 2018; Mooley et al. 2018a; Troja et al. 2017; Alexander et al. 2018; Dobie et al. 2018; Lyman et al. 2018; Ruan et al. 2018).”
• A Decline in the X-Ray through Radio Emission from GW170817 Continues to Support an Off-axis Structured Jet (2018, methodology): “…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).”
• 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): “The parameters in this model are overall comparable to the two-component model in terms of the ejecta masses and velocities of the bluer and redder components, but here the ejecta in The Astrophysical Journal Letters, 851:L21 (12pp), 2017 December 10 Villar et al. the redder component are distribute”
• Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo (2018, neutral): “A subsequent post-merger transient (AT 2017gfo) was observed across the electromagnetic spectrum, from radio(Alexander et al. 2017), to near-IR/optical(Chornock et al. 2017; Coulter et al. 2017; Cowperthwaite et al. 2017; Nicholl et al. 2017; Pian et al. 2017; Soares-Santos et al. 2017), to X-ray(Ma”
• The progenitors of compact-object binaries: impact of metallicity, common envelope and natal kicks (2018, background): “…radiation over a large range of wavelengths, from radio to gamma-rays (Abbott et al. 2017e; Goldstein et al. 2017; Savchenko et al. 2017; Margutti et al. 2017; Coulter et al. 2017; Soares-Santos et al. 2017; Chornock et al. 2017; Cowperthwaite et al. 2017; Nicholl et al. 2017; Pian et…”
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VI. Radio Constraints on a Relativistic Jet and Predictions for Late-time Emission from the Kilonova Ejecta (2017, methodology): “Together with our detailed X-ray analysis (Margutti et al. 2017), we use the radio data to place tight constraints on the presence of an on- or off-axis jet.”
• Merging black holes in young star clusters (2019, background): “…all the electromagnetic spectrum, from radio to gamma rays (Abbott et al. 2017d; Abbott et al. 2017e; Goldstein et al. 2017; Savchenko et al. 2017; Margutti et al. 2017; Coulter et al. 2017; Soares-Santos et al. 2017; Chornock et al. 2017; Cowperthwaite et al. 2017; Nicholl et al. 2017; Pian et…”
• A Magnetar Origin for the Kilonova Ejecta in GW170817 (2018, background): “…in this case would have been observationally conspicuous and thus is disfavored (Granot et al. 2017; Ma et al. 2017; Margalit & Metzger 2017; Margutti et al. 2017; Pooley et al. 2017). neutrino heating of the surrounding accretion disk (e.g., Metzger & Fernández 2014; Perego et al. 2014;…”