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All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

X-ray observations of radio-jet galaxies

The possibility that the morphology of radio-galaxy jets may be influenced by interaction with X ray emitting gaseous halos led to a study of several jet galaxies with the Einstein Observatory. These observations carried out with the IPC had a high detection rate (5 out of the 6 radio galaxies observed). The X ray data for these objects are presented. The X ray luminosities lie between about 10 to the 42nd and 10 to the 45th erg/sec. The X ray emission was found to be extended for the two galaxies with the most counts. 3C130 and 3C449. Three of the detected galaxies are known to be associated with clusters and we suggest that 3C130 may also be associated with a cluster.

Miley, G. K.↗
NASA NTRS1996

High-Resolution X-Ray Imaging of Colliding Radio-Jet Galaxies

We received ROSAT data for four program objects:3C31,3C278,3C449,and NGC1044. The first three sources were observed with the ROSAT HRI instrument. Our plan was to use the HRI to image the hot gas distribution in a few pairs of strongly disturbed interacting elliptical galaxies which are also strong radio sources having a bent-jet source morphology. The PSPC was used for NGC1044 in order to obtain a flux measurement to use in planning future High Resolution Imager (HRI) observations of that source. Though we never requested such HRI observations of NGC1044, others have used those archival PSPC data from our project for other research projects and analyses. The goal of the program was to elucidate the detailed distribution of hot gas into which the jets flow. The X-ray data were consequently analyzed in conjunction with existing VLA radio maps, optical broad-band and H-alpha Charge Couple device (CCD) images, and optical kinematic data to constrain models for the propagation of ballistic jets in interacting galaxies. We were able to test and validate the claimed causal connection between tidal interaction, the presence of gas, and the onset of activity in galaxies. The full multi-wavelength multi-observatory analyses described here are still on-going and will be published in the future. Because of the relevance of this research to on-going work in the field of active galaxies, the grant was used to support travel to several scientific meetings where our x-ray analysis, numerical modeling, and related radio results were presented and discussed.

Born, Kirk D.↗
NASA NTRS1998

A Radio-Jet-Galaxy Interaction in 3C441

Multi-wavelength imaging and spectroscopy of the zeta = 0.708 radio galaxy 3C441 and a red aligned optical/infrared component are used to show that the most striking aspect of the radio-optical "alignment effect" in this object is due to the interaction of the radio jet with a companion galaxy in the same group or cluster. The stellar population of the red aligned continuum component is predominately old, but with a small post-starburst population superposed, and it is surrounded by a low surface- brightness halo, possibly a face-on spiral disc. The [OIII]500.7/[OII]372.7 emission line ratio changes dramatically from one side of the component to the other, with the low-ionisation material apparently having passed through the bow shock of the radio source and been compressed. A simple model for the interaction is used to explain the velocity shifts in the emission line gas, and to predict that the ISM of the interacting galaxy is likely to escape once the radio source bow shock has passed though. We also discuss another, much fainter, aligned component, and the sub-arcsecond scale alignment of the radio source host galaxy. Finally we comment on the implications of our explanation of 3C441 for theories of the alignment effect.

Lacy, Mark↗
NASA NTRS2011

High Resolution Rapid Response Observations of Compact Radio Sources with the Ceduna Hobart Interferometer (CHI)

Context. Frequent, simultaneous observations across the electromagnetic spectrum are essential to the study of a range of astrophysical phenomena including Active Galactic Nuclei. A key tool of such studies is the ability to observe an object when it flares i.e. exhibits a rapid and significant increase in its flux density. Aims. We describe the specific observational procedures and the calibration techniques that have been developed and tested to create a single baseline radio interferometer. that can rapidly observe a flaring object. This is the only facility that is dedicated to rapid high resolution radio observations of an object south of -30 degrees declination. An immediate application is to provide rapid contemporaneous radio coverage of AGN flaring at y-ray frequencies detected by the Fermi Gamma-ray Space Telescope. Methods. A single baseline interferometer was formed with radio telescopes in Hobart, Tasmania and Ceduna, South Australia. A software correlator was set up at the University of Tasmania to correlate these data. Results. Measurements of the flux densities of flaring objects can be made using our observing strategy within half an hour of a triggering event. These observations can be calibrated with amplitude errors better than 20%. Lower limits to the brightness temperatures of the sources can also be calculated using CHI. Key words. instrumentation:interferometers - galaxies:active - galaxies:jets - galaxies:nuclei quasars:general gamma rays:galaxies- 1.

Blanchard, Jay M.↗
DOE OSTI2025

A multifrequency study of sub-parsec jets with the Event Horizon Telescope

Context. The 2017 observing campaign of the Event Horizon Telescope (EHT) delivered the first very long baseline interferometry (VLBI) images at the observing frequency of 230 GHz, leading to a number of unique studies on black holes and relativistic jets from active galactic nuclei (AGN). In total, eighteen sources were observed, including the main science targets, Sgr A* and M 87, and various calibrators. Sixteen sources were AGN.Aims. We investigated the morphology of the sixteen AGN in the EHT 2017 data set, focusing on the properties of the VLBI cores: size, flux density, and brightness temperature. We studied their dependence on the observing frequency in order to compare it with the Blandford-Königl (BK) jet model. In particular, we aimed to study the signatures of jet acceleration and magnetic energy conversion.Methods. We modeled the source structure of seven AGN in the EHT 2017 data set using linearly polarized circular Gaussian components (1749+096, 1055+018, BL Lac, J0132–1654, J0006–0623, CTA 102, and 3C 454.3) and collected results for the other nine AGN from dedicated EHT publications, complemented by lower frequency data in the 2–86 GHz range. Combining these data into a multifrequency EHT+ data set, we studied the dependences of the VLBI core component flux density, size, and brightness temperature on the frequency measured in the AGN host frame (and hence on the distance from the central black hole), characterizing them with power law fits. We compared the observations with the BK jet model and estimated the magnetic field strength dependence on the distance from the central black hole.Results. Our observations spanning event horizon to parsec scales indicate a deviation from the standard BK model, particularly in the decrease of the brightness temperature with the observing frequency. Only some of the discrepancies may be alleviated by tweaking the model parameters or the jet collimation profile. Either bulk acceleration of the jet material, energy transfer from the magnetic field to the particles, or both are required to explain the observations. For our sample, we estimate a general radial dependence of the Doppler factor δ ∝ r≤0.5. This interpretation is consistent with a magnetically accelerated sub-parsec jet. We also estimate a steep decrease of the magnetic field strength with radius B ∝ r−3, hinting at jet acceleration or efficient magnetic energy dissipation.Key words: techniques: interferometric / galaxies: active / galaxies: jets / galaxies: nuclei / quasars: general / quasars: supermassive black holes⋆⋆ Deceased.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Energy Spectrum and Mass Composition of Ultra-high-energy Cosmic Rays Originating from Relativistic Jets of Nearby Radio Galaxies

Relativistic jets of radio galaxies (RGs) are possible sources of ultra-high-energy cosmic rays (UHECRs). Recent studies combining relativistic hydrodynamic simulations with Monte Carlo particle transport have demonstrated that UHECRs can be accelerated to energies beyond 10 20 eV through shocks, turbulence, and relativistic shear in jet-induced flows of Fanaroff–Riley type RGs. The resulting time-asymptotic UHECR spectrum is well modeled by a double power law with an “extended” exponential cutoff, primarily shaped by relativistic shear acceleration. In this study, we adopt this novel source spectrum and simulate the propagation of UHECRs from nearby RGs using the CRPropa code. We focus on Virgo A (Vir A), Centaurus A (Cen A), Fornax A (For A), and Cygnus A (Cyg A), expected to be the most prominent UHECR sources among RGs. We then analyze the energy spectrum and mass composition of UHECRs arriving at Earth. We find that, due to the extended high-energy tail in the source spectrum, UHECRs from Vir A, which has a higher Lorentz factor, exhibit a higher flux at the highest energies and a lighter mass composition at Earth compared to those from Cen A and For A with lower Lorentz factors. Despite Cyg A having an even higher Lorentz factor, the large distance limits its contribution. With a small number of nearby prominent RGs, our findings suggest that if RGs are the major sources of UHECRs, the energy spectrum and mass composition of observed UHECRs would exhibit hemispheric differences between the Northern and Southern skies at the highest energies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Event Horizon Telescope imaging of the archetypal blazar 3C 279 at an extreme 20 microarcsecond resolution

3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique – global Very Long Baseline Interferometry (VLBI) at 1.3 mm (230 GHz) – to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable γ-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array (ALMA), at an angular resolution of ∼20 μas (at a redshift of z = 0.536 this corresponds to ∼0.13 pc ∼ 1700 Schwarzschild radii with a black hole mass MBH = 8 × 108 M⊙). Imaging and model-fitting techniques were applied to the data to parameterize the fine-scale source structure and its variation. We find a multicomponent inner jet morphology with the northernmost component elongated perpendicular to the direction of the jet, as imaged at longer wavelengths. The elongated nuclear structure is consistent on all four observing days and across different imaging methods and model-fitting techniques, and therefore appears robust. Owing to its compactness and brightness, we associate the northern nuclear structure as the VLBI “core”. This morphology can be interpreted as either a broad resolved jet base or a spatially bent jet. We also find significant day-to-day variations in the closure phases, which appear most pronounced on the triangles with the longest baselines. Our analysis shows that this variation is related to a systematic change of the source structure. Two inner jet components move non-radially at apparent speeds of ∼15 c and ∼20 c (∼1.3 and ∼1.7 μas day−1, respectively), which more strongly supports the scenario of traveling shocks or instabilities in a bent, possibly rotating jet. The observed apparent speeds are also coincident with the 3C 279 large-scale jet kinematics observed at longer (cm) wavelengths, suggesting no significant jet acceleration between the 1.3 mm core and the outer jet. The intrinsic brightness temperature of the jet components are ≲1010 K, a magnitude or more lower than typical values seen at ≥7 mm wavelengths. The low brightness temperature and morphological complexity suggest that the core region of 3C 279 becomes optically thin at short (mm) wavelengths.Key words: galaxies: active / galaxies: jets / galaxies: individual: 3C 279 / techniques: interferometric⋆ The data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/640/A69 and at https://eventhorizontelescope.org/for-astronomers/data⋆⋆ Deceased.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2009

Observations of M87 and Hydra A at 90 GHz

This paper presents new observations of the AGNs M87 and Hydra A at 90 GHz made with the MUSTANG bolometer array on the Green Bank Telescope at 8.5" resolution. A spectral analysis is performed combining this new data and archival VLA data or1 these objects at longer wavelengths. This analysis can detect variations in spectral index and curvature expected from energy losses in the radiating particles. L187 shows only weak evidence for steepening of the spectrum along the jet suggesting either re-acceleration of the relativistic particles in the jet or insufficient los~esto affect the spectrum at 90 GHz The jets in Hydra A show strong steepening as they move from the nucleus suggesting unbalanced losses of the higher energy relativistic particles The difference between these two sources may be accounted for by the different lengths over which the jets are observable, 2 kpc for 5187 and 45 kpc for Hydra A. Subject headings: galaxies: jets, galaxies: active, radio continuum, galaxies: individual (M87. Hydra A),

Cotton, W. D.↗
NASA NTRS1986

Bubbles and braided jets in galaxies with compact radio nuclei

Narrow-band H-alpha CCD images showing ionized gas in organized kiloparsec-scale structures in three galaxies with low-level active nuclei are presented. The edge-on spiral NGC 3079 contains an apparent loop structure which corresponds to previously reported nonthermal radio emission along the minor axis. The optical emission probably results from interaction between the ejected plasma and the ISM in the disk and halo. The S0 galaxy NGC 3998 exhibits an S-shaped structure centered on the nucleus, with no other evidence for spiral structure. In the spiral galaxy NGC 4258, the presence of continuum-free emission-line arms which coincide with the nonthermal radio arms is confirmed. The morphology of the arms suggests the presence of two double-sided jets which braid or wrap around one another and which bifurcate on both sides. It is concluded that the optical and radio emission in NGC 3079 and in NGC 4258 are related, and it is suggested that both are powered by a plasma which flows from the active nucleus and dissipates kinetic energy in the surrounding ISM.

Ford, Holland C.↗
DOE OSTI2023

Simulations of Precessing Jets and the Formation of X-shaped Radio Galaxies

Abstract Jet precession is sometimes invoked to explain asymmetries in radio galaxy (RG) jets and “X/S/Z-shaped” RGs, caused by the presence of a binary black hole companion to the source active galactic nucleus or by accretion instabilities. We present a series of simulations of RG jet precession to examine how these sources would evolve over time, including a passive distribution of cosmic-ray electrons so we can model radio synchrotron emissions and create synthetic radio maps of the sources. We find that a single source viewed from different angles can result in differing RG morphological classifications, confusing physical implications of these classifications. Additionally, the jet trajectories can become unstable due to their own self-interactions and lead to “reorientation events” that may look like the effects of external dynamics such as shocks, winds, or cold fronts in the medium. Finally, something akin to an “Odd Radio Circle” may be observed in the case of viewing the radio remnant of such a precessing source from a line of sight near the precession axis.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2019

Dissecting the AGN Disk-Jet System with Joint VLBI-Gaia Analysis

We analyze differences in positions of active galactic nuclei (AGNs) between Gaia data release 2 and very long baseline interferometry (VLBI) and compare the significant VLBI-to-Gaia offsets in more than 1000 objects with their jet directions. Remarkably at least three-fourths of the significant offsets are confirmed to occur downstream or upstream of the jet representing a genuine astrophysical effect. Introducing redshift and Gaia color into analysis can help distinguish between the contribution of the host galaxy, jet, and accretion disk emission. We find that strong optical jet emission at least 20-50 pc long is required to explain the Gaia positions located downstream fromVLBI ones. Offsets in the upstream direction of up to 2 mas are at least partly due to the dominant impact of the accretion disk on the Gaia coordinates and by the effects of the parsec-scale radio jet. The host galaxy was found not to play an important role in the detected offsets. BL Lacertae object and Seyfert 2 galaxies are observationally confirmed to have a relatively weak disk and consequently downstream offsets. The disk emission drives upstream offsets in a significant fraction of quasars and Seyfert 1 galaxies when it dominates over the jet in the optical band. The observed behavior of the different AGN classes is consistent with the unified scheme assuming varying contribution of the obscuring dusty torus and jet beaming.

Plavin, A. V.↗
NASA NTRS1994

Discovery of an obscured low luminosity active nucleus in the spiral galaxy NGC 4258

The spectra and images of the nearby jet galaxy NGC 4258 (M106) obtained with ASCA indicate presence of several distinct X-ray emission components. The emission above 3 keV is pointlike and coincident in position with the optical nucleus, exhibiting a hard (photon index approximately 1.78) and absorbed N(sub H) approximately 1.5 x 10(exp 23) cm(exp -2) spectrum. This provides clear evidence that NGC 4258 hosts an obscured active nucleus of low luminosity, about 4 x 10(exp 40) ergs s(exp -1) in 2-10 keV after removing the absorption. Iron K-line emission with an equivalent width 0.25 +/- 0.10 keV was detected. The emission below 1 keV is dominated by an extended approximately 4 min thin-thermal component with a temperature approximately 0.5 keV exhibiting atomic emission lines, possibly associated with the jet. There exists a third continuum component with an intermediate spectral hardness, which is brightest at approximately 1 min south-east of the nucleus.

Makishima, Kazuo↗
DOE OSTI2024

Multiwavelength investigations of PKS 2300–18: S-shaped radio quasar with precessing jets and double-peaked broad emission-line spectrum

ABSTRACT S-shaped radio galaxy jets are prime sources for investigating the dynamic interplay between the central active galactic nucleus (AGN), the jets, and the ambient intergalactic medium. These sources are excellent candidates for studying jet precession, as their S-shaped inversion symmetry strongly indicates underlying precession. We present a multiwavelength analysis of the giant inversion-symmetric S-shaped radio galaxy PKS 2300$-$18, which spans 0.76 Mpc. The host is a quasar at a redshift of 0.128, displaying disturbed optical morphology due to an ongoing merger with a companion galaxy. We conducted a broad-band radio spectral study using multifrequency data ranging from 183 MHz to 6 GHz, incorporating dedicated observations with the upgraded Giant Metrewave Radio Telescope (uGMRT) and Karl G. Jansky Very Large Array (JVLA) alongside archival radio data. A particle injection model was fitted to the spectra of different regions of the source to perform ageing analysis, which was supplemented with a kinematic jet precession model. The ageing analysis revealed a maximum plasma age of $\sim$ 40 Myr, while the jet precession model indicated a precession period of $\sim$ 12 Myr. ROentgen SATellite (ROSAT) data revealed an X-ray halo of Mpc size, and from Chandra the AGN X-ray spectrum was modelled using thermal and power-law components. The optical spectrum displaying double-peaked broad emission lines was modelled, indicating complex broad-line region kinematics at the centre with the possibility of a binary SMBH. We present the results of our multiwavelength analysis of the source, spanning scales from a few light-days to a few Mpc, and discuss its potential evolutionary path.

Misra, Arpita↗
DOE OSTI2024

Ordered magnetic fields around the 3C 84 central black hole

Context. 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz.Aims. Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84.Methods. We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure.Results. We report the detection of a highly ordered, strong magnetic field around the central, supermassive black hole of 3C 84. The brightness temperature analysis suggests that the system is in equipartition. We also determined a turnover frequency of νm = (113 ± 4) GHz, a corresponding synchrotron self-absorbed magnetic field of BSSA = (2.9 ± 1.6) G, and an equipartition magnetic field of Beq = (5.2 ± 0.6) G. Three components are resolved with the highest fractional polarisation detected for this object (mnet = (17.0 ± 3.9)%). The positions of the components are compatible with those seen in low-frequency VLBI observations since 2017–2018. We report a steeply negative slope of the spectrum at 228 GHz. We used these findings to test existing models of jet formation, propagation, and Faraday rotation in 3C 84.Conclusions. The findings of our investigation into different flow geometries and black hole spins support an advection-dominated accretion flow in a magnetically arrested state around a rapidly rotating supermassive black hole as a model of the jet-launching system in the core of 3C 84. However, systematic uncertainties due to the limited (u, v)-coverage, however, cannot be ignored. Our upcoming work using new EHT data, which offer full imaging capabilities, will shed more light on the compact region of 3C 84.Key words: techniques: high angular resolution / techniques: interferometric / galaxies: active / galaxies: individual: NGC 1275 / galaxies: jets

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1993

Ballistic Models for Radio Jets in Colliding Galaxies: 3C 278 (NGC 4782/4783)

We present here a general numerical simulation algorithm for ballistic radio jets. The evolution of the jets is determined by their response to mechanical forces (i.e., gravity and ram pressure). Using a previously derived collision model for the interacting pair of elliptical galaxies NGC 4782/4783, we have used this algorithm to simulate the specific two-sided jet morphology seen in the radio source associated with NGC 4782 (3C 278). This is the first time such simulations have been attempted for a galaxy pair whose relative orbit was determined independently from the jet modeling. The general morphological features of the jets in 3C 278 (e.g., position angles, lengths, curvature, and deflection angles) are well matched by the simulations, indicating that our model of the mechanical forces acting on the jets can indeed reproduce most of the basic details of the jet morphology and thereby provide an opportunity to model a combination of detailed optical, radio, and X-ray data for a wide variety of interacting radio-jet galaxies. Our models constrain the initial jet parameters (i.e., the ejection speed, direction, and starting time), the properties of the gaseous medium into which the jets are ejected, and the relative importance of gravitational deflection versus ram pressure bending in influencing the jet morphology. For 3C 278, we find that the effects of ram pressure dominate the structural evolution of the jets. In our best-fit simulation the jet ejection speed is of order 10(exp 4) km/s, to within 50%, suggesting that similar low-luminosity radio jets are also significantly subluminal. We also find that the jets are ejected within approximately 5 deg of the line of sight, the ISM in the nonjet galaxy has a much larger effect on the jet deflection than does the host galaxy, and the jet activity began just over 70 million years ago, roughly 50 million years before the pericenter passage of the two galaxies. Therefore, the onset of nuclear activity appears in 3C 278 to be related to the kinematically observed tidal shock that has been induced in the core of NGC 4782 as a result of its deeply penetrating collision with NGC 4783.

Borne, Kirk D.↗
NASA NTRS2011

Dual-Frequency VLBI Study of Centaurus A on Sub-Parsec Scales: The Highest-Resolution View of an Extragalactic Jet

Centaurus A is the closest active galactic nucleus. High resolution imaging using Very Long Baseline Interferometry (VLBI) enables us to study the spectral and kinematic behavior of the radio jet-<:ounterjet system on sub-parsec scales, providing essential information for jet emission and formation models. Aims. Our aim is to study the structure and spectral shape of the emission from the central-parsec region of Cen A. Methods. As a target of the Southern Hemisphere VLBI monitoring program TANAMI (Tracking Active Galactic Nuclei with Millliarcsecond Interferometry), VLBI observations of Cen A are made regularly at 8.4 and 22.3 GHz with the Australian Long Baseline Array (LBA) and associated telescopes in Antarctica, Chile, and South Africa. Results. The first dual-frequency images of this source are presented along with the resulting spectral index map. An angular resolution of 0.4 mas x 0.7 mas is achieved at 8.4 GHz, corresponding to a linear scale of less than 0.013 pc. Hence, we obtain the highest resolution VLBI image of Cen A, comparable to previous space-VLBI observations. By combining with the 22.3 GHz image, we present the corresponding dual-frequency spectral index distribution along the sub-parsec scale jet revealing the putative emission regions for recently detected y-rays from the core region by Fermi/LAT. Conclusions. We resolve the innermost structure of the milliarcsecond scale jet and counter jet system of Cen A into discrete components. The simultaneous observations at two frequencies provide the highest resolved spectral index map of an AGN jet allowing us to identify up to four possible sites as the origin of the high energy emission. Key words. galaxies: active galaxies: individual (Centaurus A, NGC 5128) - galaxies: jets - techniques: high angular resolution

Mueller, C.↗
NASA NTRS1993

Radio jets in colliding galaxies: Testing the interaction-activity connection

The idea that galaxy interactions and merging are related to the generation of starburst and AGN activity in galactic nuclei has been the subject of intensive investigations over the past several years and is still a matter of lively debate. Peculiar morphologies, indicative of tidal interactions, have been detected in high-luminosity radio galaxies, in quasars, and in ultraluminous IRAS galaxies. In addition, low-luminosity radio and active galaxies show similar evidence for a recent merger or for nearby companions. In a recent CCD optical study of galaxies selected on the basis that they all contain well defined radio jets, it was found that almost half of the sample consists of pairs of elliptical galaxies. Many of these low-luminosity radio galaxies with companions show a well defined distorted radio jet structure at the VLA scale with an S- or C-shaped morphology. We have developed a general numerical simulation algorithm for ballistic radio jets with the intention of applying this model to the study of the bent jets seen in colliding pairs of galaxies and with the hope of testing the well documented interaction-activity connection. In our model the morphological evolution of the jets is determined by their response to the simple mechanical forces (i.e., gravity and ram pressure) imposed on them from both the host and the companion galaxies. Radiative losses, jet precession, magnetic effects, relativistic terms, and hydrodynamic instabilities have all been ignored. Starting with a previously derived collision model for the interacting pair of elliptical galaxies NGC 4782/4783, we have used our algorithm to simulate the specific two-sided jet morphology seen in the radio source 3C 278, associated with NGC 4782. This is the first time that such jet simulations have been produced for a galaxy pair whose relative orbit was determined independently from the jet modeling.

Borne, Kirk D.↗
NASA NTRS2012

Radio Detections During Two State Transitions of the Intermediate-Mass Black Hole HLX-1

Relativistic jets are streams of plasma moving at appreciable fractions of the speed of light. They have been observed from stellar-mass black holes (approx. 3 to 20 solar masses) as well as supermassive black holes (approx.. 10(exp 6) to 10(exp 9) Solar Mass) found in the centers of most galaxies. Jets should also be produced by intermediate-mass black holes (approx. 10(exp 2) to 10(exp 5) Solar Mass), although evidence for this third class of black hole has, until recently, been weak. We report the detection of transient radio emission at the location of the intermediate-mass black hole candidate ESO 243-49 HLX-1, which is consistent with a discrete jet ejection event. These observations also allow us to refine the mass estimate of the black hole to be between approx. 9 × 10(exp 3) Solar Mass and approx. 9 × 10(exp 4) Solar Mass.

transitions↗