First ALMA Light Curve Constrains Refreshed Reverse Shocks and Jet Magnetization in GRB 161219B
Year: 2018
Type: article
Abstract: We present detailed multiwavelength observations of GRB 161219B at z = 0.1475, spanning the radio to X-ray regimes, and the first Atacama Large Millimeter/submillimeter Array (ALMA) light curve of a γ -ray burst (GRB) afterglow. The centimeter- and millimeter-band observations before 8.5 days require emission in excess of that produced by the afterglow forward shock (FS). These data are consistent with radiation from a refreshed reverse shock (RS) produced by the injection of energy into the FS, signatures of which are also present in the X-ray and optical light curves. We infer a constant-density circumburst environment with an extremely low density, , and show that this is a characteristic of all strong RS detections to date. The Karl G. Lansky Very Large Array (VLA) observations exhibit unexpected rapid variability on roughly minute timescales, indicative of strong interstellar scintillation. The X-ray, ALMA, and VLA observations together constrain the jet break time, days, yielding a wide jet opening angle of , implying beaming-corrected γ -ray and kinetic energies of erg and erg, respectively. Comparing the RS and FS emission, we show that the ejecta are only weakly magnetized, with relative magnetization, , compared to the FS. These direct, multifrequency measurements of a refreshed RS spanning the optical to radio bands highlight the impact of radio and millimeter data in probing the production and nature of GRB jets.
Source: The Astrophysical Journal
Authors: Tanmoy Laskar, Kate D. Alexander, Edo Berger, Cristiano Guidorzi, Raffaella Margutti, Wen-fai Fong, Charles D. Kilpatrick, Peter Milne, Maria R. Drout, C. G. Mundell, Shiho Kobayashi, Ragnhild Lunnan, Rodolfo Barniol Duran, Karl M. Menten, Kunihito Ioka, Peter K. G. Williams
Institutions: National Radio Astronomy Observatory, University of California, Berkeley, Harvard University, University of Ferrara, Northwestern University, University of California, Santa Cruz, University of Arizona, Carnegie Institution for Science, Carnegie Observatories, University of Bath, Liverpool John Moores University, California Institute of Technology, Stockholm University, AlbaNova, California State University, Sacramento, Max Planck Institute for Radio Astronomy, Kyoto University, Yukawa Institute for Theoretical Physics
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Science Foundation, National Aeronautics and Space Administration, W. M. Keck Foundation, California Institute of Technology, National Radio Astronomy Observatory, University of Leicester, National Science Council, Korea Astronomy and Space Science Institute, National Astronomical Observatory of Japan, Goddard Space Flight Center, Science and Technology Facilities Council, Japan Society for the Promotion of Science, National Institutes of Natural Sciences
Awards: Liverpool Telescope Operations 2017-2019, GAMMA-RAY BURSTS: PROGENITORS TO PROBES IN A MANNER REMINISCENT OF QUASARS AND TYPE IA SUPERNOVAE, THE STUDY OF LONG-DURATION GAMMA-RAY BURSTS (LGRBS, Theoretical Study of High-Energy Multimessengers from PeV Sources, Gamma-Ray Bursts: From Progenitors to Probes, LT Operations Extension April - September 2014, Liverpool Telescope Operations 2014-2016, Liverpool Telescope Operations Oct 2016 - Mar 2017
OpenAlex ID: W2883266651