ORCID Profile
0000-0003-0234-7940
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Astronomical and Space Sciences | Astronomy And Astrophysics | Cosmology and Extragalactic Astronomy | Galactic Astronomy | Astronomical and Space Instrumentation | Cosmic Ray Physics | Atomic, Molecular, Nuclear, Particle and Plasma Physics | Numerical Analysis | Other Plasma Physics | Fluid Physics | Numerical Computation | Plasmas And Electrical Discharges
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Physical sciences | Expanding Knowledge in Technology | Application packages | Mathematical sciences | International relations not elsewhere classified | Expanding Knowledge in the Information and Computing Sciences | Higher education |
Related Links
Publications
Jet-intracluster medium interaction in Hydra A - II. The effect of jet precession
Publisher: Oxford University Press (OUP)
Date: 15-02-2016
DOI: 10.1093/MNRAS/STW330
Erratum: Relativistic jet feedback in high-redshift galaxies I. Dynamics
Publisher: Oxford University Press (OUP)
Date: 14-07-2017
Modelling observable signatures of jet-ISM interaction: thermal emission and gas kinematics
Publisher: Oxford University Press (OUP)
Date: 11-08-2022
Abstract: Relativistic jets are believed to have a substantial impact on the gas dynamics and evolution of the interstellar medium (ISM) of their host galaxies. In this paper, we aim to draw a link between the simulations and the observable signatures of jet-ISM interactions by analyzing the emission morphology and gas kinematics resulting from jet-induced shocks in simulated disc and spherical systems. We find that the jet-induced laterally expanding forward shock of the energy bubble sweeping through the ISM causes large-scale outflows, creating shocked emission and high-velocity dispersion in the entire nuclear regions (∼2 kpcs) of their hosts. The jetted systems exhibit larger velocity widths (& km s−1), broader Position-Velocity maps and distorted symmetry in the disc’s projected velocities than systems without a jet. We also investigate the above quantities at different inclination angles of the observer with respect to the galaxy. Jets inclined to the gas disc of its host are found to be confined for longer times, and consequently couple more strongly with the disc gas. This results in prominent shocked emission and high-velocity widths, not only along the jet’s path, but also in the regions perpendicular to them. Strong interaction of the jet with a gas disc can also distort its morphology. However, after the jets escape their initial confinement, the jet-disc coupling is weakened, thereby lowering the shocked emission and velocity widths.
Relativistic jet feedback in high-redshift galaxies - I. Dynamics
Publisher: Oxford University Press (OUP)
Date: 08-06-2016
Centrifugally driven winds from protostellar accretion discs – I. Formulation and initial results
Publisher: Oxford University Press (OUP)
Date: 30-06-2017
Relativistic jet feedback - II. Relationship to gigahertz peak spectrum and compact steep spectrum radio galaxies
Publisher: Oxford University Press (OUP)
Date: 10-01-2018
DOI: 10.1093/MNRAS/STY070
RELATIVISTIC JET FEEDBACK IN EVOLVING GALAXIES
Publisher: American Astronomical Society
Date: 17-01-2011
The extent of ionization in simulations of radio-loud AGNs impacting kpc gas discs
Publisher: Oxford University Press (OUP)
Date: 28-01-2022
Abstract: We use the results of relativistic hydrodynamic simulations of jet-interstellar medium (ISM) interactions in a galaxy with a radio-loud AGN to quantify the extent of ionization in the central few kpcs of the gaseous galactic disc. We perform post-process radiative transfer of AGN radiation through the simulated gaseous jet-perturbed disc to estimate the extent of photo-ionization by the AGN with an incident luminosity of 1045 erg s−1. We also map the gas that is collisionally ionized due to shocks driven by the jet. The analysis was carried out for simulations with similar jet power (1045 erg s−1) but different jet orientations with respect to the gas disc. We find that the shocks from the jets can ionize a significant fraction (up to 33 ${{\\ \\rm per\\ cent}}$) of dense gas ($n\\gt 100\\, \\mathrm{cm^{-3}}$) in the disc, and that the jets clear out the central regions of gas for AGN radiation to penetrate to larger distances in the disc. Jets inclined towards the disc plane couple more strongly with the ISM and ionize a larger fraction of gas in the disc as compared to the vertical jet. However, similar to previous studies, we find that the AGN radiation is quickly absorbed by the outer layers of dense clouds in the disc, and is not able to substantially ionize the disc on a global scale. Thus, compared to jet–ISM interactions, we expect that photo-ionization by the AGN radiation only weakly affects the star-formation activity in the central regions of the galactic disc (≲ 1 kpc), although the jet-induced shocks can spread farther out.
PERIODIC STRUCTURE IN THE MEGAPARSEC-SCALE JET OF PKS 0637–752
Publisher: American Astronomical Society
Date: 27-09-2012
Accretion discs in blazars
Publisher: Oxford University Press (OUP)
Date: 11-12-2009
DRIVING OUTFLOWS WITH RELATIVISTIC JETS AND THE DEPENDENCE OF ACTIVE GALACTIC NUCLEUS FEEDBACK EFFICIENCY ON INTERSTELLAR MEDIUM INHOMOGENEITY
Publisher: American Astronomical Society
Date: 12-09-2012
MULTI-DIMENSIONAL SIMULATIONS OF THE EXPANDING SUPERNOVA REMNANT OF SN 1987A
Publisher: American Astronomical Society
Date: 07-10-2014
How frequent are close supermassive binary black holes in powerful jet sources?
Publisher: Oxford University Press (OUP)
Date: 21-09-2018
ULTRAFAST OUTFLOWS: GALAXY-SCALE ACTIVE GALACTIC NUCLEUS FEEDBACK
Publisher: American Astronomical Society
Date: 04-01-2013
The Kinematics and Ionization of Nuclear Gas Clouds in Centaurus A
Publisher: American Astronomical Society
Date: 05-03-2013
Jet-intracluster medium interaction in Hydra A - I. Estimates of jet velocity from inner knots
Publisher: Oxford University Press (OUP)
Date: 29-08-2014
The jet–ISM interactions in IC 5063
Publisher: Oxford University Press (OUP)
Date: 22-01-2018
DOI: 10.1093/MNRAS/STY067
Jets blowing bubbles in the young radio galaxy 4C 31.04
Publisher: Oxford University Press (OUP)
Date: 23-01-2019
DOI: 10.1093/MNRAS/STZ233
Searching for signs of jet-driven negative feedback in the nearby radio galaxy UGC 05771
Publisher: Oxford University Press (OUP)
Date: 05-09-2019
Abstract: Hydrodynamical simulations predict that the jets of young radio sources can inhibit star formation in their host galaxies by injecting heat and turbulence into the interstellar medium (ISM). To investigate jet–ISM interactions in a galaxy with a young radio source, we have carried out a multiwavelength study of the z = 0.025 Compact Steep Spectrum radio source hosted by the early-type galaxy UGC 05771. Using Keck/OSIRIS observations, we detected H2 1–0 S(1) and [Fe ii] emission at radii of 100s of parsecs, which traces shocked molecular and ionized gas being accelerated outwards by the jets to low velocities, creating a ‘stalling wind’. At kpc radii, we detected shocked ionized gas using observations from the CALIFA survey, covering an area much larger than the pc-scale radio source. We found that existing interferometric radio observations fail to recover a large fraction of the source’s total flux, indicating the likely existence of jet plasma on kpc scales, which is consistent with the extent of shocked gas in the host galaxy. To investigate the star formation efficiency in UGC 05771, we obtained IRAM CO observations to analyse the molecular gas properties. We found that UGC 05771 sits below the Kennicutt–Schmidt relation, although we were unable to definitively conclude if direct interactions from the jets are inhibiting star formation. This result shows that jets may be important in regulating star formation in the host galaxies of compact radio sources.
Galaxy-scale AGN feedback - theory
Publisher: Wiley
Date: 02-2016
Abstract: Powerful relativistic jets in radio galaxies are capable of driving strong outflows but also inducing star‐formation by pressure‐triggering collapse of dense clouds. We review theoretical work on negative and positive active galactic nuclei feedback, discussing insights gained from recent hydrodynamical simulations of jet‐driven feedback on galaxy scales that are applicable to compact radio sources. The simulations show that the efficiency of feedback and the relative importance of negative and positive feedback depend strongly on interstellar medium properties, especially the column depth and spatial distribution of clouds. Negative feedback is most effective if clouds are distributed spherically and in idual clouds have small column depths, while positive feedback is most effective if clouds are predominantly in a disc‐like configuration. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
STEADY-STATE HADRONIC GAMMA-RAY EMISSION FROM 100-MYR-OLD FERMI BUBBLES
Publisher: American Astronomical Society
Date: 30-07-2014
Filament formation in wind-cloud interactions- II. Clouds with turbulent density, velocity, and magnetic fields
Publisher: Oxford University Press (OUP)
Date: 28-09-2018
Unravelling the enigmatic ISM conditions in Minkowski’s object
Publisher: Oxford University Press (OUP)
Date: 12-10-2020
Abstract: Local ex les of jet-induced star formation lend valuable insight into its significance in galaxy evolution and can provide important observational constraints for theoretical models of positive feedback. Using optical integral field spectroscopy, we present an analysis of the ISM conditions in Minkowski’s object (z = 0.0189), a peculiar star-forming dwarf galaxy located in the path of a radio jet from the galaxy NGC 541. Full spectral fitting with ppxf indicates that Minkowski’s object primarily consists of a young stellar population $\\sim \\! 10\\, \\rm Myr$ old, confirming that the bulk of the object’s stellar mass formed during a recent jet interaction. Minkowski’s object exhibits line ratios largely consistent with star formation, although there is evidence for a low level ($\\lesssim \\! 15 \\, \\rm per \\, cent$) of contamination from a non-stellar ionizing source. Strong-line diagnostics reveal a significant variation in the gas-phase metallicity within the object, with $\\log \\left(\\rm O / H \\right) + 12$ varying by $\\sim \\! 0.5\\, \\rm dex$, which cannot be explained by in-situ star formation, an enriched outflow from the jet, or enrichment of gas in the stellar bridge between NGC 541 and NGC 545/547. We hypothesize that Minkowski’s object either (i) was formed as a result of jet-induced star formation in pre-existing gas clumps in the stellar bridge, or (ii) is a gas-rich dwarf galaxy that is experiencing an elevation in its star formation rate due to a jet interaction, and will eventually redden and fade, becoming an ultradiffuse galaxy as it is processed by the cluster.
A UNIFIED MODEL OF THE FERMI BUBBLES, MICROWAVE HAZE, AND POLARIZED RADIO LOBES: REVERSE SHOCKS IN THE GALACTIC CENTER’S GIANT OUTFLOWS
Publisher: American Astronomical Society
Date: 24-07-2015
O VI Emission in Nuclear Region of NGC 1068
Publisher: AIP
Date: 2009
DOI: 10.1063/1.3154085
OPTICAL IFU OBSERVATIONS OF THE BRIGHTEST CLUSTER GALAXY NGC 4696: THE CASE FOR A MINOR MERGER AND SHOCK-EXCITED FILAMENTS
Publisher: American Astronomical Society
Date: 11-2010
Tracing the Milky Way’s Vestigial Nuclear Jet
Publisher: American Astronomical Society
Date: 12-2021
Abstract: MeerKAT radio continuum and XMM-Newton X-ray images have recently revealed a spectacular bipolar channel at the Galactic Center that spans several degrees (∼0.5 kpc). An intermittent jet likely formed this channel and is consistent with earlier evidence of a sustained, Seyfert-level outburst fueled by black hole accretion onto Sgr A* several Myr ago. Therefore, to trace a now weak jet that perhaps penetrated, deflected, and percolated along multiple paths through the interstellar medium, relevant interactions are identified and quantified in archival X-ray images, Hubble Space Telescope Paschen α images and Atacama Large Millimeter/submillimeter Array millimeter-wave spectra, and new SOAR telescope IR spectra. Hydrodynamical simulations are used to show how a nuclear jet can explain these structures and inflate the ROSAT/eROSITA X-ray and Fermi γ -ray bubbles that extend ± 75° from the Galactic plane. Thus, our Galactic outflow has features in common with energetic, jet-driven structures in the prototypical Seyfert galaxy NGC 1068.
Revolutionizing Our Understanding of AGN Feedback and its Importance to Galaxy Evolution in the Era of the Next Generation Very Large Array
Publisher: American Astronomical Society
Date: 18-05-2018
Impact of relativistic jets on the star formation rate: a turbulence-regulated framework
Publisher: Oxford University Press (OUP)
Date: 02-10-2021
Abstract: We apply a turbulence-regulated model of star formation to calculate the star formation rate (SFR) of dense star-forming clouds in simulations of jet–interstellar medium (ISM) interactions. The method isolates in idual clumps and accounts for the impact of virial parameter and Mach number of the clumps on the star formation activity. This improves upon other estimates of the SFR in simulations of jet–ISM interactions, which are often solely based on local gas density, neglecting the impact of turbulence. We apply this framework to the results of a suite of jet–ISM interaction simulations to study how the jet regulates the SFR both globally and on the scale of in idual star-forming clouds. We find that the jet strongly affects the multiphase ISM in the galaxy, inducing turbulence and increasing the velocity dispersion within the clouds. This causes a global reduction in the SFR compared to a simulation without a jet. The shocks driven into clouds by the jet also compress the gas to higher densities, resulting in local enhancements of the SFR. However, the velocity dispersion in such clouds is also comparably high, which results in a lower SFR than would be observed in galaxies with similar gas mass surface densities and without powerful radio jets. We thus show that both local negative and positive jet feedback can occur in a single system during a single jet event, and that the SFR in the ISM varies in a complicated manner that depends on the strength of the jet–ISM coupling and the jet break-out time-scale.
Relativistic jet feedback - III. Feedback on gas discs
Publisher: Oxford University Press (OUP)
Date: 05-07-2018
Turbulent mixing layers in supersonic protostellar outflows, with application to DG Tauri
Publisher: Oxford University Press (OUP)
Date: 19-11-2016
ERRATUM: “RELATIVISTIC JET FEEDBACK IN EVOLVING GALAXIES” (2011, ApJ, 728, 29)
Publisher: American Astronomical Society
Date: 17-08-2011
Tracing the Ionization Structure of the Shocked Filaments of NGC 6240
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We study the ionization and excitation structure of the interstellar medium in the late-stage gas-rich galaxy merger NGC 6240 using a suite of emission-line maps at ∼25 pc resolution from the Hubble Space Telescope, Keck/NIRC2 with Adaptive Optics, and the Atacama Large Millimeter/submillimeter Array (ALMA). NGC 6240 hosts a superwind driven by intense star formation and/or one or both of two active nuclei the outflows produce bubbles and filaments seen in shock tracers from warm molecular gas (H 2 2.12 μ m) to optical ionized gas ([O iii ], [N ii ], [S ii ], and [O i ]) and hot plasma (Fe XXV ). In the most distinct bubble, we see a clear shock front traced by high [O iii ]/H β and [O iii ]/[O i ]. Cool molecular gas (CO(2−1)) is only present near the base of the bubble, toward the nuclei launching the outflow. We interpret the lack of molecular gas outside the bubble to mean that the shock front is not responsible for dissociating molecular gas, and conclude that the molecular clouds are partly shielded and either entrained briefly in the outflow, or left undisturbed while the hot wind flows around them. Elsewhere in the galaxy, shock-excited H 2 extends at least ∼4 kpc from the nuclei, tracing molecular gas even warmer than that between the nuclei, where the two galaxies’ interstellar media are colliding. A ridgeline of high [O iii ]/H β emission along the eastern arm aligns with the southern nucleus’ stellar disk minor axis optical integral field spectroscopy from WiFeS suggests this highly ionized gas is centered at systemic velocity and likely photoionized by direct line of sight to the southern active galactic nucleus.
Related Organisations
No related organisations have been discovered for Geoffrey Bicknell.
Related Funding Activities
Discovery Projects - Grant ID: DP1096417
Start Date: 2010
End Date: 12-2013
Amount: $330,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0664434
Start Date: 2006
End Date: 12-2011
Amount: $440,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP140103341
Start Date: 2014
End Date: 12-2017
Amount: $399,231.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0345983
Start Date: 07-2003
End Date: 12-2006
Amount: $300,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE0238884
Start Date: 2001
End Date: 12-2002
Amount: $220,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE210100015
Start Date: 11-2021
End Date: 10-2025
Amount: $1,680,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE150100070
Start Date: 2015
End Date: 12-2015
Amount: $270,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE170100104
Start Date: 07-2017
End Date: 07-2023
Amount: $1,390,000.00
Funder: Australian Research Council
View Funded Activity