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

Makhathini, S, Mooley, KP, Brightman, M, Hotokezaka, K, Nayana, AJ, Intema, HT, Dobie, D, Lenc, E, Perley, DA, Fremling, C, Moldòn, J, Lazzati, D, Kaplan, DL, Balasubramanian, A, Brown, IS, Carbone, D, Chandra, P, Corsi, A, Camilo, F, Deller, A , Frail, DA, Murphy, T, Murphy, EJ, Nakar, E, Smirnov, O, Beswick, RJ, Fender, R, Hallinan, G, Heywood, I, Kasliwal, M, Lee, B, Lu, W, Rana, J, Perkins, S, White, SV, Józsa, GIG, Hugo, B and Kamphuis, P (2021) The Panchromatic Afterglow of GW170817: The Full Uniform Data Set, Modeling, Comparison with Previous Results, and Implications. The Astrophysical Journal, 922 (2). ISSN 0004-637X

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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 t0.86±0.04 rise, a t−1.92±0.12 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, <0.01 cm−3, 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 1010.4 and 1016 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.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical and Space Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, 0306 Physical Chemistry (incl. Structural)
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: American Astronomical Society
Date Deposited: 09 Dec 2021 12:37
Last Modified: 26 Nov 2022 00:51
DOI or ID number: 10.3847/1538-4357/ac1ffc
URI: https://researchonline.ljmu.ac.uk/id/eprint/15904
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