Conveners
Accretion-ejection (observation, theory, simulations)
- Dave Russell (New York University Abu Dhabi)
Accretion-ejection (observation, theory, simulations): Flash Talk
- Dave Russell (New York University Abu Dhabi)
Accretion-ejection (observation, theory, simulations)
- Sara Elisa Motta (Istituto Nazionale di Astrofisica (INAF))
Accretion-ejection (observation, theory, simulations)
- Alexandra Tetarenko (University of Lethbridge)
Jets are a ubiquitous phenomenon in all classes of accreting stellar-mass compact objects; white dwarfs, neutron stars, and black holes. From the observations, it is clear that jet production appears to be fundamentally related to the process of accretion, however, the precise nature of the coupling remains to be determined. In this talk, I will review what recent (and not so recent) observing...
Matter accreting onto the surface of a neutron star can ignite in a thermonuclear explosion visible as a ~1-min long bright flash of X-ray emission. Such thermonuclear X-ray bursts radiate a total energy of ~E39 erg and can recur on a timescale of hours. Every time an explosion goes off, a strong radiation field suddenly floods the direct environment of the neutron star and observations have...
Accreting low-mass X-ray binaries (LMXBs) provide a unique testbed to investigate the complex interplay between accretion flows and relativistic jets. In both neutron star and black hole systems LMXBs, X-ray and radio emissions are observed to be correlated, though neutron star systems exhibit significantly lower radio fluxes at comparable X-ray luminosities. Among neutron star LMXBs,...
Neutron star X-ray binaries often exhibit Type-I X-ray bursts, during which the X-ray luminosity can rise up to 100 times the persistent flux. These bursts are triggered by unstable thermonuclear burning of accreted hydrogen and/or helium on the neutron star’s surface. In certain instances, two bursts are observed in close succession, typically separated by an interval of 10–20 minutes. The...
Ultraluminous X-ray sources (ULXs) are accreting stellar compact objects whose X-ray luminosities exceed the Eddington limit. In order to get more insights on the nature of their accreting compact object (black hole or neutron star) and the geometries of super-Eddington accretion flows, it is useful to look at the influence of ULXs on their environment. I will present how VLT/MUSE 3-D...
We report the results obtained from the analysis of XMM–Newton observations together with simultaneous NICER and NuSTAR observations of the ultraluminous X-ray source NGC 4190 ULX-1. Our goal is to constrain the structure of the accretion disk and the geometrical properties of the source, performing temporal and spectral analyses in the 0.4−30 keV energy range. The temporal analysis shows no...
Ultraluminous X-ray sources (ULXs) are thought to be powered by super-Eddington accretion onto stellar-mass compact objects and represent the high-luminosity end of accreting binary systems. Here, we report the discovery of a new transient ULX candidate (M51 ULX*) in the face-on spiral galaxy M51, identified using archival Swift, XMM-Newton, and Chandra data. The source underwent a short-lived...
We have used The Chandra Source Catalog to extract light curves of point sources from nearby galaxies, ULXs, and 25 nearby (z lt 0.2) QSOs. We have Chandra grating observations of 25 Galactic XRBs adjusted to ACIS count rates at a distance of 1 Mpc. A three-dimensional color-color-RelInt diagram shows that the distribution of ULXs is well matched in both color and luminosity with point...
Accretion states, which are universally observed in stellar-mass black holes in X-ray binaries, are also anticipated in active galactic nuclei (AGN). The luminosity-excitation diagram (LED), based on IR nebular emission-line ratios, successfully identifies distinct accretion regimes in AGN —from jet/corona-dominated emission in low-luminosity AGN (LLAGN) to disc-dominated emission in Seyfert...
We present a reanalysis of archive radio interferometric data for the gamma-ray binary LS I +61303. Our aim is to expand our previous searches for associated extended emission at the few arc-second/arc-minute level. The existence of such large scale features is expected no matter the physical scenario that is really at work in this system: pulsar wind interaction or microquasar. The main...
We investigate the 2018 main outburst and the subsequent mini-outbursts of the black hole low-mass X-ray binary MAXI J1820+070 using optical/ultraviolet data from the Las Cumbres Observatory (LCO), the American Association of Variable Star Observers (AAVSO), and SWIFT/UVOT, as well as X-ray data from Insight-HXMT and SWIFT/XRT. Given the high-cadence observations, we identify a broad dip-like...
Jet emitting disks (JEDs) provide the theoretical framework of mathematically exact steady-state accretion and ejection solutions. A large-scale vertical magnetic field threads a turbulent, strongly magnetized, accretion disk driving laminar, bipolar, super-Alfvénic jets. In previous treatments of JEDs, turbulence has been considered to provide only anomalous transport coefficients, namely...
Superluminal ejections were first reported from microquasars almost thirty years ago. Their apparent superluminal motion is due to discrete, relativistic, collimated ejections of plasma launched from the vicinity of the black hole, during hard-to-soft state transitions. It is suspected, but not definitively proven, that these jets are fed from particles in the highly energetic corona, rather...
Astrophysical systems housing compact objects produce high-energy transient events that can be leveraged to study the processes of accretion and jet ejection. In particular, thermonuclear fusion on the surface of accreting neutron stars produces bursts of X-ray radiation that not only strongly impact the accretion structures in these systems, but as a recent novel experiment has shown, can...
Swift J1727.8-1613 is a recently discovered black hole low-mass X-ray binary (BH LMXB) that began its first recorded outburst in the autumn of 2023. The source rapidly became one of the brightest X-ray sources in the sky — reaching an X-ray flux nearly an order of magnitude greater than that of the Crab Nebula — and prompted a comprehensive multi-wavelength observing campaign. The radio...
For decades, high angular resolution VLBI observations of X-ray binary jets have been key to understanding the physics of jet launching. By precisely tracking the motions of transient jets, and thus inferring their ejection date, we can learn about the causal connection between changes in the inner accretion flow and the launching of jets. These efforts are often hindered by the difficulty of...
Measuring the Lorentz factors of jets from black holes is essential for understanding the jet launching mechanisms and overall energy budget of the black holes themselves. However, this is a notoriously difficult task due to special relativistic effects which are exacerbated for off-axis sources, namely X-ray binary (XRB) jets. In fact, from kinematics alone we find that, remarkably, we can...
Mini-HAWKs is a 50 sqr deg pathfinder of the Galactic Plane down to r≃21 that employs 3 custom Hα filters, optimized to select targets with very broad Hα emission lines. These are the hallmark of strong gravitational fields as they are typically formed in accretion discs around black holes (BHs). Mini-HAWKs will prove a novel photometric strategy that, when extended to the entire northern...
