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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

A Multi-wavelength Characterization of the 2023 Outburst of MAXI J1807+132: Manifestations of Disk Instability and Jet Emission

(2025)

Authors:

Sandeep K Rout, M Cristina Baglio, Andrew Hughes, David M Russell, DM Bramich, Payaswini Saikia, Kevin Alabarta, Montserrat Armas Padilla, Sergio Campana, Stefano Covino, Paolo D'Avanzo, Rob Fender, Paolo Goldoni, Jeroen Homan, Fraser Lewis, Nicola Masetti, Sara Motta, Teo Munoz-Darias, Alessandro Papitto, Thomas D Russell, Gregory Sivakoff, Jakob van den Eijnden

A Persistent Disk Wind and Variable Jet Outflow in the Neutron-star Low-mass X-Ray Binary GX 13+1

The Astrophysical Journal American Astronomical Society 986:1 (2025) 41

Authors:

Daniele Rogantini, Jeroen Homan, Richard M Plotkin, Maureen van den Berg, James Miller-Jones, Joey Neilsen, Deepto Chakrabarty, Rob P Fender, Norbert Schulz

Abstract:

In low-mass X-ray binaries (LMXBs), accretion flows are often associated with either jet outflows or disk winds. Studies of LMXBs with luminosities up to roughly 20% of the Eddington limit indicate that these outflows generally do not co-occur, suggesting that disk winds might inhibit jets. However, previous observations of LMXBs accreting near or above the Eddington limit show that jets and winds can potentially coexist. To investigate this phenomenon, we carried out a comprehensive multiwavelength campaign (using the Very Large Array (VLA), Chandra/High Energy Transmission Grating Spectrometer (HETG), and NICER) on the near-Eddington neutron-star Z-source LMXB GX 13+1. NICER and Chandra/HETG observations tracked GX 13+1 across the entire Z track during high Eddington rates, detecting substantial resonance absorption features originating from the accretion disk wind in all X-ray spectra, which implies a persistent wind presence. Simultaneous VLA observations captured a variable radio jet, with radio emission notably strong during all flaring branch observations—contrary to typical behavior in Z sources—and weaker when the source was on the normal branch. Interestingly, no clear correlation was found between the radio emission and the wind features. Analysis of VLA radio light curves and simultaneous Chandra/HETG spectra demonstrates that an ionized disk wind and jet outflow can indeed coexist in GX 13+1, suggesting that their launching mechanisms are not necessarily linked in this system.
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Gone with the Wind: JWST-MIRI Unveils a Strong Outflow from the Quiescent Stellar-Mass Black Hole A0620-00

(2025)

Authors:

Zihao Zuo, Gabriele Cugno, Joseph Michail, Elena Gallo, David M Russell, Richard M Plotkin, Fan Zou, M Cristina Baglio, Piergiorgio Casella, Fraser J Cowie, Rob Fender, Poshak Gandhi, Sera Markoff, Federico Vincentelli, Fraser Lewis, Jon M Miller, James CA Miller-Jones, Alexandra Veledina
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Relativistic ejecta from stellar mass black holes: insights from simulations and synthetic radio images

Monthly Notices of the Royal Astronomical Society Oxford University Press 540:1 (2025) 1084-1106

Authors:

Katie Savard, James H Matthews, Rob Fender, Ian Heywood

Abstract:

We present numerical simulations of discrete relativistic ejecta from an X-ray binary (XRB) with initial conditions directly informed by observations. XRBs have been observed to launch powerful discrete plasma ejecta during state transitions, which can propagate up to parsec distances. Understanding these ejection events unveils new understanding of jet-launching, jet power, and jet–interstellar medium (ISM) interaction among other implications. Multifrequency quasi-simultaneous radio observations of ejecta from the black hole XRB MAXI J1820+070 produced both size and calorimetry constraints, which we use as initial conditions of a relativistic hydrodynamic simulation. We qualitatively reproduce the observed deceleration of the ejecta in a homogeneous ISM. Our simulations demonstrate that the ejecta must be denser than the ISM, the ISM be significantly low density, and the launch be extremely powerful, in order to propagate to the observed distances. The blob propagates and clears out a high-pressure low-density cavity in its wake, providing an explanation for this pre-existing low-density environment, as well as ‘bubble-like’ environments in the vicinity of XRBs inferred from other studies. As the blob decelerates, we observe the onset of instabilities and a long-lived reverse shock – these mechanisms convert kinetic to internal energy in the blob, responsible for in situ particle acceleration. We transform the outputs of our simulation into pseudo-radio images, incorporating the coverage of the MeerKAT and e-MERLIN telescopes from the original observations with real-sky background. Through this, we maximize the interpretability of the results and provide direct comparison to current data, as well as provide prediction capabilities.
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MeerKAT discovery of a hyperactive repeating fast radio burst source

Monthly Notices of the Royal Astronomical Society Oxford University Press 540:2 (2025) 1685-1700

Authors:

J Tian, I Pastor-Marazuela, KM Rajwade, BW Stappers, K Shaji, KY Hanmer, M Caleb, MC Bezuidenhout, F Jankowski, R Breton, ED Barr, M Kramer, PJ Groot, S Bloemen, P Vreeswijk, D Pieterse, PA Woudt, RP Fender, RAD Wijnands, DAH Buckley

Abstract:

We present the discovery and localization of a repeating fast radio burst (FRB) source from the MeerTRAP project, a commensal fast radio transient search programme using the MeerKAT telescope. FRB 20240619D was first discovered on 2024 June 19 with three bursts being detected within 2 min in the MeerKAT L band (856–1712 MHz). We conducted follow-up observations of FRB 20240619D with MeerKAT using the Ultra-High Frequency (UHF; MHz), L-band and S-band (1968–2843 MHz) receivers one week after its discovery, and recorded a total of 249 bursts. The MeerKAT-detected bursts exhibit band-limited emission with an average fractional bandwidth of 0.31, 0.34, and 0.48 in the UHF, L-band, and S-band, respectively. We find our observations are complete down to a fluence limit of Jy ms, above which the cumulative burst rate follows a power law with and in the UHF and L band, respectively. The near-simultaneous L-band, UHF, and S-band observations reveal a frequency dependent burst rate with more bursts being detected in the L band than in the UHF and S band, suggesting a spectral turnover in the burst energy distribution of FRB 20240619D. Our polarimetric analysis demonstrates that most of the bursts have linear polarization fractions and circular polarization fractions. We find no optical counterpart of FRB 20240619D in the MeerLICHT optical observations simultaneous to the radio observations and set a fluence upper limit in MeerLICHT’s q band of 0.76 Jy ms and an optical-to-radio fluence ratio limit of 0.034 for a 15 s exposure.
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