The Panchromatic Afterglow of GW170817: The Full Uniform Data Set, Modeling, Comparison with Previous Results, and Implications

DOI: 
10.3847/1538-4357/ac1ffc
Publication date: 
24/12/2021
Main author: 
Makhathini, S.
IAA authors: 
Moldòn, J.
Authors: 
Makhathini, S.;Mooley, K. P.;Brightman, M.;Hotokezaka, K.;Nayana, A. J.;Intema, H. T.;Dobie, D.;Lenc, E.;Perley, D. A.;Fremling, C.;Moldòn, J.;Lazzati, D.;Kaplan, D. L.;Balasubramanian, A.;Brown, I. S.;Carbone, D.;Chandra, P.;Corsi, A.;Camilo, F.;Deller, A.;Frail, D. A.;Murphy, T.;Murphy, E. J.;Nakar, E.;Smirnov, O.;Beswick, R. J.;Fender, R.;Hallinan, G.;Heywood, I.;Kasliwal, M.;Lee, B.;Lu, W.;Rana, J.;Perkins, S.;White, S. V.;Józsa, G. I. G.;Hugo, B.;Kamphuis, P.
Journal: 
The Astrophysical Journal
Publication type: 
Article
Volume: 
922
Pages: 
154
Abstract: 
We present the full panchromatic afterglow light-curve data of GW170817, including new radio data as well as archival optical and X-ray data, between 0.5 and 940 days post-merger. By compiling all archival data and reprocessing a subset of it, we have evaluated the impact of differences in data processing or flux determination methods used by different groups and attempted to mitigate these differences to provide a more uniform data set. Simple power-law fits to the uniform afterglow light curve indicate a t <SUP>0.86±0.04</SUP> rise, a t <SUP>-1.92±0.12</SUP> decline, and a peak occurring at 155 ± 4 days. The afterglow is optically thin throughout its evolution, consistent with a single spectral index (-0.584 ± 0.002) across all epochs. This gives a precise and updated estimate of the electron power-law index, p = 2.168 ± 0.004. By studying the diffuse X-ray emission from the host galaxy, we place a conservative upper limit on the hot ionized interstellar medium density, &lt;0.01 cm<SUP>-3</SUP>, consistent with previous afterglow studies. Using the late-time afterglow data we rule out any long-lived neutron star remnant having a magnetic field strength between 10<SUP>10.4</SUP> and 10<SUP>16</SUP> G. Our fits to the afterglow data using an analytical model that includes Very Long Baseline Interferometry proper motion from Mooley et al., and a structured jet model that ignores the proper motion, indicates that the proper-motion measurement needs to be considered when seeking an accurate estimate of the viewing angle.
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2021ApJ...922..154M/abstract
ADS Bibcode: 
2021ApJ...922..154M
Keywords: 
678;675;739;1108;1324;Astrophysics - High Energy Astrophysical Phenomena;Astrophysics - Astrophysics of Galaxies;Astrophysics - Solar and Stellar Astrophysics