A mildly relativistic wide-angle outflow in the neutron star merger GW170817
| Autor: | Mooley, K. P., Nakar, E., Hotokezaka, K., Hallinan, G., Corsi, A., Frail, D. A., Horesh, A., Murphy, T., Lenc, E., Kaplan, D. L., De, K., Dobie, D., Chandra, P., Deller, A., Gottlieb, O., Kasliwal, M. M., Kulkarni, S. R., Myers, S. T., Nissanke, S., Piran, T., Lynch, C., Bhalerao, V., Bourke, S., Bannister, K. W., Singer, L. P. |
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| Rok vydání: | 2017 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/nature25452 |
| Popis: | GW170817 is the first gravitational wave detection of a binary neutron star merger. It was accompanied by radiation across the electromagnetic spectrum and localized to the galaxy NGC 4993 at a distance of 40 Mpc. It has been proposed that the observed gamma-ray, X-ray and radio emission is due to an ultra-relativistic jet launched during the merger, directed away from our line of sight. The presence of such a jet is predicted from models positing neutron star mergers as the central engines driving short-hard gamma-ray bursts (SGRBs). Here we show that the radio light curve of GW170817 has no direct signature of an off-axis jet afterglow. While we cannot rule out the existence of a jet pointing elsewhere, the observed gamma-rays could not have originated from such a jet. Instead, the radio data requires a mildly relativistic wide-angle outflow moving towards us. This outflow could be the high velocity tail of the neutron-rich material dynamically ejected during the merger or a cocoon of material that breaks out when a jet transfers its energy to the dynamical ejecta. The cocoon scenario can explain the radio light curve of GW170817 as well as the gamma-rays and X-rays (possibly also ultraviolet and optical emission), and hence is the model most consistent with the observational data. Cocoons may be a ubiquitous phenomenon produced in neutron star mergers, giving rise to a heretofore unidentified population of radio, ultraviolet, X-ray and gamma-ray transients in the local universe. Comment: 41 pages, 4 figures (main text), 4 figures (supplementary text), 1 table. This revised version incorporates comments from the referees |
| Databáze: | arXiv |
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