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Relativistic Jet from Black Hole

An artist's impression of a relativistic jet propagating away from a black hole at close to the speed of light. Such jets are formed by the inner regions of the accretion flow: matter flowing inwards towards the black hole, via processes which are not yet fully understood. The accretion flow emits primarily in X-rays, the relativistic jet in the radio band: by combing observations in each band we can try and understand how such jets form and how much energy they carry away from the black hole.

Professor Rob Fender

Professor of Astrophysics

Research theme

  • Astronomy and astrophysics

Sub department

  • Astrophysics

Research groups

  • Hintze Centre for Astrophysical Surveys
  • MeerKAT
  • Pulsars, transients and relativistic astrophysics
  • Rubin-LSST
  • The Square Kilometre Array (SKA)
  • Gamma-ray astronomy
Rob.Fender@physics.ox.ac.uk
Telephone: 01865 (2)73435
Denys Wilkinson Building, room 712
  • About
  • Publications

Relativistic ejecta from stellar mass black holes: insights from simulations and synthetic radio images

(2025)

Authors:

Katie Savard, James H Matthews, Rob Fender, Ian Heywood
More details from the publisher

MeerKAT discovers a jet-driven bow shock near GRS 1915+105. How an invisible large-scale jet sculpts a microquasar's environment

(2025)

Authors:

SE Motta, P Atri, James H Matthews, Jakob van den Eijnden, Rob P Fender, James CA Miller-Jones, Ian Heywood, Patrick Woudt
More details from the publisher
Details from ArXiV

Quantifying jet-interstellar medium interactions in Cyg X-1: Insights from dual-frequency bow shock detection with MeerKAT

(2025)

Authors:

P Atri, SE Motta, Jakob van den Eijnden, James H Matthews, James CA Miller-Jones, Rob Fender, David Williams-Baldwin, Ian Heywood, Patrick Woudt
More details from the publisher

Jets from a stellar-mass black hole are as relativistic as those from supermassive black holes

(2025)

Authors:

Xian Zhang, Wenfei Yu, Francesco Carotenuto, Rob Fender, Sara Motta, Arash Bahramian, James CA Miller-Jones, Thomas D Russell, Stephane Corbel, Patrick A Woudt, Pikky Atri, Christian Knigge, Gregory R Sivakoff, Andrew K Hughes, Jakob van den Eijnden, James Matthews, Maria C Baglio, Payaswini Saikia

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

Monthly Notices of the Royal Astronomical Society Oxford University Press 539:3 (2025) 2665-2684

Authors:

James H Matthews, Alex J Cooper, Lauren Rhodes, Katherine Savard, Rob Fender, Francesco Carotenuto, Fraser J Cowie, Emma L Elley, Joe Bright, Andrew K Hughes, Sara E Motta

Abstract:

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 () and moderately relativistic () 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 10–100 of 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.
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Details from ORA
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