Abstract
We present the results of our year-long afterglow monitoring of GW 170817, the first binary neutron star merger detected by Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo. New observations with the Australian Telescope Compact Array and the ChandraX-ray Telescope were used to constrain its late-time behaviour. The broad-band emission, from radio to X-rays, is well-described by a simple power-law spectrum with index β ∼ 0.585 at all epochs. After an initial shallow rise ∝t0.9, the afterglow displayed a smooth turnover, reaching a peak X-ray luminosity of LX ≈ 5 × 10 39 erg s -1 at 160 d, and has now entered a phase of rapid decline, approximately ∝t -2. The latest temporal trend challenges most models of choked jet/cocoon systems, and is instead consistent with the emergence of a relativistic structured jet seen at an angle of ≈22° from its axis. Within such model, the properties of the explosion (such as its blast wave energy EK ≈ 2 × 10 50 erg, jet width θc ≈ 4°, and ambient density n ≈ 3 × 10 -3 cm -3) fit well within the range of properties of cosmological short gamma-ray bursts.
Original language | English |
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Pages (from-to) | 1919-1926 |
Number of pages | 8 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 489 |
Issue number | 2 |
Early online date | 13 Aug 2019 |
DOIs | |
Publication status | Published - 1 Oct 2019 |
Keywords
- Acceleration of particles
- Gamma-ray burst: General
- Gravitational waves
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
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Hendrik Van Eerten
- Department of Physics - Reader
- Astrophysics - Head of Group
Person: Research & Teaching, Core staff