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

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2025)

Authors:

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

Abstract:

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-ISM interaction among other implications. Multi-frequency 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 interstellar medium (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 u, v 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.

Abundant Population of Broad H$\alpha$ Emitters in the GOODS-N Field Revealed by CONGRESS, FRESCO, and JADES

(2025)

Authors:

Junyu Zhang, Eiichi Egami, Fengwu Sun, Xiaojing Lin, Jianwei Lyu, Yongda Zhu, Pierluigi Rinaldi, Yang Sun, Andrew J Bunker, Rachana Bhatawdekar, Jakob M Helton, Roberto Maiolino, Zheng Ma, Brant Robertson, Sandro Tacchella, Giacomo Venturi, Christina C Williams, Chris Willott

The Large-scale Environments of Low-luminosity AGNs at $3.9 < z < 6$ and Implications for Their Host Dark Matter Halos from a Complete NIRCam Grism Redshift Survey

(2025)

Authors:

Xiaojing Lin, Xiaohui Fan, Fengwu Sun, Junyu Zhang, Eiichi Egami, Jakob M Helton, Feige Wang, Haowen Zhang, Andrew J Bunker, Zheng Cai, Zhiyuan Ji, Xiangyu Jin, Roberto Maiolino, Maria Anne Pudoka, Pierluigi Rinaldi, Brant Robertson, Sandro Tacchella, Wei Leong Tee, Yang Sun, Christopher NA Willmer, Chris Willott, Yongda Zhu

The origin of the very-high-energy radiation along the jet of Centaurus A

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 539:4 (2025) 3697-3713

Authors:

Cainã de Oliveira, James H Matthews, Vitor de Souza

Strong gravitational lenses from the Vera C. Rubin Observatory

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences The Royal Society 383:2295 (2025) 20240117

Authors:

Anowar J Shajib, Graham P Smith, Simon Birrer, Aprajita Verma, Nikki Arendse, Thomas Collett, Tansu Daylan, Stephen Serjeant

Abstract:

Like many areas of astrophysics and cosmology, the Vera C. Rubin Observatory will be transformational for almost all the applications of strong lensing, thanks to the dramatic increase in the number of known strong lenses by two orders of magnitude or more and the readily available time-domain data for the lenses with transient sources. In this article, we provide an overview of the forecasted number of discovered lenses of different types and describe the primary science cases these large lens samples will enable. We provide an updated forecast on the joint constraint for the dark energy equation-of-state parameters, w0 and wa, from combining all strong-lensing probes of dark energy. We update the previous forecast from the Rubin Observatory Dark Energy Science Collaboration’s Science Review Document by adding two new crucial strong-lensing samples: lensed type Ia supernovae and single-deflector lenses with measured stellar kinematics. Finally, we describe the current and near-future activities and collaborative efforts within the strong-lensing community in preparation for the arrival of the first real dataset from Rubin in 2026. This article is part of the Theo Murphy meeting issue ‘Multi-messenger gravitational lensing (Part 2)’.