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Modelling synchrotron self-Compton and Klein–Nishina effects in gamma-ray burst afterglows

Jacovich, Taylor E. and Beniamini, Paz and van der Horst, Alexander J (2021) Modelling synchrotron self-Compton and Klein–Nishina effects in gamma-ray burst afterglows. Monthly Notices of the Royal Astronomical Society, 504 (1). pp. 528-542. ISSN 0035-8711. doi:10.1093/mnras/stab911.

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We present an implementation of a self-consistent way of modelling synchrotron self-Compton (SSC) effects in gamma-ray burst afterglows, with and without approximated Klein–Nishina suppressed scattering for the afterglow modelling code BOXFIT, which is currently based on pure synchrotron emission. We discuss the changes in spectral shape and evolution due to SSC effects, and comment on how these changes affect physical parameters derived from broad-band modelling. We show that SSC effects can have a profound impact on the shape of the X-ray light curve using simulations including these effects. This leads to data that cannot be simultaneously fit well in both the X-ray and radio bands when considering synchrotron-only fits, and an inability to recover the correct physical parameters, with some fitted parameters deviating orders of magnitude from the simulated input parameters. This may have a significant impact on the physical parameter distributions based on previous broad-band modelling efforts.

Item Type:Article
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URLURL TypeDescription Paper ItemData/Code ItemData/Code
Jacovich, Taylor E.0000-0003-0226-0343
Beniamini, Paz0000-0001-7833-1043
Additional Information:© 2021 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 March 26. Received 2021 February 18; in original form 2020 July 8. Published: 06 April 2021. The authors would like to thank HJ van Eerten for useful suggestions on several aspects of the work presented here. TEJ would also like to thank MJ Moss and SI Chastain for discussions on the theoretical framework, and G McCarthy for verifying aspects of the mathematical framework. TEJ acknowledges support from NASA Astrophysical Theory Program #80NSSC18K0566. He additionally acknowledges support from the Chandra X-ray Center, which is operated by the Smithsonian Institution under NASA contract NAS8-03060. Some of the computations in this paper were conducted on the George Washington University High Performance Computing Cluster, Colonial One, and on the Smithsonian High Performance Cluster (SI/HPC), Smithsonian Institution ( The research of PB was funded by the Gordon and Betty Moore Foundation through grant GBMF5076. This work made use of the following software packages: MATPLOTLIB (Hunter 2007), NASA ADS, NUMPY (van der Walt, Colbert & Varoquaux 2011), and PANDAS (McKinney 2010). Data Availability: The data sets generated for this article will be available in SSC-sample-data at SSC_boxfit will be made public once finalized at
Funding AgencyGrant Number
Gordon and Betty Moore FoundationGBMF5076
Subject Keywords:radiation mechanisms: non-thermal – relativistic processes – methods: numerical – gamma-ray burst: general
Issue or Number:1
Record Number:CaltechAUTHORS:20210630-191220692
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Official Citation:Taylor E Jacovich, Paz Beniamini, Alexander J van der Horst, Modelling synchrotron self-Compton and Klein–Nishina effects in gamma-ray burst afterglows, Monthly Notices of the Royal Astronomical Society, Volume 504, Issue 1, June 2021, Pages 528–542,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109676
Deposited By: Tony Diaz
Deposited On:30 Jun 2021 22:49
Last Modified:30 Jun 2021 22:49

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