Blast waves and reverse shocks: from ultra-relativistic GRBs to moderately relativistic X-ray binaries

Fuente: arXiv
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Main Authors: Matthews, James H., Cooper, Alex J., Rhodes, Lauren, Savard, Katherine, Fender, Rob, Carotenuto, Francesco, Cowie, Fraser J., Elley, Emma L., Bright, Joe, Hughes, Andrew K., Motta, Sara E.
Format: Preprint
Published: 2025
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author Matthews, James H.
Cooper, Alex J.
Rhodes, Lauren
Savard, Katherine
Fender, Rob
Carotenuto, Francesco
Cowie, Fraser J.
Elley, Emma L.
Bright, Joe
Hughes, Andrew K.
Motta, Sara E.
author_facet Matthews, James H.
Cooper, Alex J.
Rhodes, Lauren
Savard, Katherine
Fender, Rob
Carotenuto, Francesco
Cowie, Fraser J.
Elley, Emma L.
Bright, Joe
Hughes, Andrew K.
Motta, Sara E.
contents Blast wave models are commonly used to model relativistic outflows from ultra-relativistic gamma-ray bursts (GRBs), but are also applied to lower Lorentz factor ejections from X-ray binaries (XRBs). Here we revisit the physics of blast waves and reverse shocks in these systems and explore the similarities and differences between the ultra-relativistic ($Γ\gg 1$) and moderately relativistic ($Γ\sim$ a few) regimes. We first demonstrate that the evolution of the blast wave radius as a function of the observer frame time is recovered in the on-axis ultra-relativistic limit from a general energy and radius blast wave evolution, emphasizing that XRB ejections are off-axis, moderately relativistic cousins of GRB afterglows. We show that, for fixed blast wave or ejecta energy, reverse shocks cross the ejecta much later (earlier) on in the evolution for less (more) relativistic systems, and find that reverse shocks are much longer-lived in XRBs and off-axis GRBs compared to on-axis GRBs. Reverse shock crossing should thus typically finish after $\sim10-100$ days (in the observer frame) in XRB ejections. This characteristic, together with their moderate Lorentz factors and resolvable core separations, makes XRB ejections unique laboratories for shock and particle acceleration physics. We discuss the impact of geometry and lateral spreading on our results, explore how to distinguish between different shock components, and comment on the implications for GRB and XRB environments. Additionally, we argue that identification of reverse shock signatures in XRBs could provide an independent constraint on the ejecta Lorentz factor.
format Preprint
id arxiv_https___arxiv_org_abs_2503_10802
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Blast waves and reverse shocks: from ultra-relativistic GRBs to moderately relativistic X-ray binaries
Matthews, James H.
Cooper, Alex J.
Rhodes, Lauren
Savard, Katherine
Fender, Rob
Carotenuto, Francesco
Cowie, Fraser J.
Elley, Emma L.
Bright, Joe
Hughes, Andrew K.
Motta, Sara E.
High Energy Astrophysical Phenomena
Blast wave models are commonly used to model relativistic outflows from ultra-relativistic gamma-ray bursts (GRBs), but are also applied to lower Lorentz factor ejections from X-ray binaries (XRBs). Here we revisit the physics of blast waves and reverse shocks in these systems and explore the similarities and differences between the ultra-relativistic ($Γ\gg 1$) and moderately relativistic ($Γ\sim$ a few) regimes. We first demonstrate that the evolution of the blast wave radius as a function of the observer frame time is recovered in the on-axis ultra-relativistic limit from a general energy and radius blast wave evolution, emphasizing that XRB ejections are off-axis, moderately relativistic cousins of GRB afterglows. We show that, for fixed blast wave or ejecta energy, reverse shocks cross the ejecta much later (earlier) on in the evolution for less (more) relativistic systems, and find that reverse shocks are much longer-lived in XRBs and off-axis GRBs compared to on-axis GRBs. Reverse shock crossing should thus typically finish after $\sim10-100$ days (in the observer frame) in XRB ejections. This characteristic, together with their moderate Lorentz factors and resolvable core separations, makes XRB ejections unique laboratories for shock and particle acceleration physics. We discuss the impact of geometry and lateral spreading on our results, explore how to distinguish between different shock components, and comment on the implications for GRB and XRB environments. Additionally, we argue that identification of reverse shock signatures in XRBs could provide an independent constraint on the ejecta Lorentz factor.
title Blast waves and reverse shocks: from ultra-relativistic GRBs to moderately relativistic X-ray binaries
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2503.10802