Статья

The Optical Afterglow of GW170817: An Off-axis Structured Jet and Deep Constraints on a Globular Cluster Origin

Wen‐fai FongCenter for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112, USAP. K. BlanchardCenter for Astrophysics∣Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138-1516, USAK. D. AlexanderCenter for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112, USAJay StraderCenter for Data Intensive and Time Domain Astronomy, Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USAR. MarguttiCenter for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112, USAA. HajelaCenter for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112, USAV. Ashley VillarCenter for Astrophysics∣Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138-1516, USAY. WuCenter for Cosmology and Particle Physics, New York University, 726 Broadway New York, NY 10003, USAClaire S. YeCenter for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112, USAE. BergerCenter for Astrophysics∣Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138-1516, USAR. ChornockAstrophysical Institute, Department of Physics and Astronomy, 251B Clippinger Lab, Ohio University, Athens, OH 45701, USAD. L. CoppejansCenter for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112, USAP. S. CowperthwaiteObservatories of the Carnegie Institute for Science, 813 Santa Barbara Street, Pasadena, CA 91101-1232, USATarraneh EftekhariCenter for Astrophysics∣Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138-1516, USADimitrios GianniosDepartment of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907, USAC. GuidorziDipartimento di Fisica, Università Ferrara, Via Paradiso 12, I-44100 Ferrara, ItalyAdithan KathirgamarajuDepartment of Astronomy and Theoretical Astrophysics Center, University of California Berkeley, Berkeley, CA 94720, USAT. LaskarDepartment of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UKAndrew MacFadyenCenter for Cosmology and Particle Physics, New York University, 726 Broadway New York, NY 10003, USABrian D. MetzgerDepartment of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USAM. NichollBirmingham Institute for Gravitational Wave Astronomy and School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UKK. PatersonCenter for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112, USAG. TerreranCenter for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3112, USADavid SandSteward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065, USALorenzo SironiDepartment of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USAPeter K. G. WilliamsAmerican Astronomical Society, 1667 K Street NW, Suite 800, Washington, DC 20006-1681, USAX. C. XieMathematical Sciences and STAG Research Centre, University of Southampton, Southampton SO17 1BJ, UKJonathan ZrakeDepartment of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA

2019en

ABI

Аннотация

Abstract We present a revised and complete optical afterglow light curve of the binary neutron star merger GW170817, enabled by deep Hubble Space Telescope ( HST ) F606W observations at ≈584 days post-merger, which provide a robust optical template. The light curve spans ≈110–362 days, and is fully consistent with emission from a relativistic structured jet viewed off-axis, as previously indicated by radio and X-ray data. Combined with contemporaneous radio and X-ray observations, we find no spectral evolution, with a weighted average spectral index of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:mi>β</mml:mi> <mml:mo stretchy="false">〉</mml:mo> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.583</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.013</mml:mn> </mml:math> , demonstrating that no synchrotron break frequencies evolve between the radio and X-ray bands over these timescales. We find that an extrapolation of the post-peak temporal slope of GW170817 to the luminosities of cosmological short gamma-ray bursts matches their observed jet break times, suggesting that their explosion properties are similar, and that the primary difference in GW170817 is viewing angle. Additionally, we place a deep limit on the luminosity and mass of an underlying globular cluster (GC) of L ≲ 6.7 × 10 3 L ⊙ , or M ≲ 1.3 × 10 4 M ⊙ , at least 4 standard deviations below the peak of the GC mass function of the host galaxy, NGC 4993. This limit provides a direct and strong constraint that GW170817 did not form and merge in a GC. As highlighted here, HST (and soon the James Webb Space Telescope ) enables critical observations of the optical emission from neutron star merger jets and outflows.

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Идентификаторы

DOI: 10.3847/2041-8213/ab3d9e

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Цитирований: 2Использованных источников: 0

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