Ambient Medium Research Articles

Simulation of the “Central Engine” of Astrophysical Jets within the Plasma Focus Facility

Laboratory plasma ejections within the plasma focus facilities (the structure of their electric currents, rotation, shock wave arising from interaction with the ambient medium) reproduce all the main elements of jets from young stars. On the other hand, the physical processes responsible for the launch of a plasma ejection are still not well understood, and therefore there is still no unequivocal answer to the question of how adequately the laboratory experiment reproduces the mechanism of astrophysical jet formation. In this paper, we formulated the conditions under which the similarity of physical processes can also take place in the “central engine” of a laboratory experiment leading to the launch of a plasma ejection, based on the analysis of the effects of nonideal magnetohydrodynamics.

Fast Outflowing Warm Absorbers in Narrow-line Seyfert 1 Galaxy PG 1001+054 Revealed by HST/COS Spectra

Narrow-line Seyfert 1 (NLS1) galaxies are an important type of active galactic nucleus (AGN), generally expected to be accreting at a high Eddington rate. The properties of their outflows and importance of AGN feedback remain intriguing. We report on the discovery of fast outflowing warm absorbers (WAs) in the NLS1 PG 1001+054 with velocities in the range of ∼7000–9000 km s−1. They are identified with blueshifted Lyα, N v, and Si iv lines in the high-resolution ultraviolet (UV) spectra taken with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. We perform photoionization modeling using XSTAR with three WAs. The derived physical properties are typical of WAs in terms of ionization and column density, whereas the outflow velocities are significantly higher. The estimated location of these WAs ranges from 1 to 73 parsecs away from the AGN. Together with previous detection of high ionization absorbers in the X-ray for PG 1001+054, we suggest that fast outflowing UV absorbers are probably part of a multiphase outflow. Such a structure is likely produced by the outflow launched from the AGN at an accretion disk scale, which shocks the ambient interstellar medium (ISM), producing stratified absorbers. Assuming contribution from the three WAs at tens of parsecs, the estimated ratio between the kinetic power of the outflow and AGN Eddington luminosity could reach 1.7%, raising the possibility of sufficient influence on the host galaxy when compared to some theoretical models for efficient AGN feedback.

Photometric and Spectroscopic Observations of GRB 210104A: Bright Reverse-shock Emission and Dense Circumburst Environment

Early afterglow observations of gamma-ray bursts (GRBs) are valuable for exploring the properties of their jets and ambient medium. We report our photometric and spectroscopic observations of GRB 210104A and discuss its jet properties with multiwavelength data. Our spectroscopic observation reveals several absorption features and a tentative redshift of 0.46 is identified. A bright optical flare that has a peak brightness of R = 13 mag at 112 ± 7 s was observed in the R band during 67 ∼ 165 s post the GRB trigger. The flux of the R-band afterglow decays with a slope of α O = − 0.91 ± 0.03 at t > 650 s. The early X-ray afterglow lightcurve is a smooth bump, and it decays with a slope of α X = −1.18 ± 0.01 at late epoch. Our joint spectral fit to the optical-X-ray afterglows during (1.1–1.3) × 104 s yields a photon index ΓO,X = −1.82 ± 0.04. The derived host galaxy extinction is A R = 0.87. Attributing the early optical flare to the reverse-shock (RS) emission and the late optical-X-ray emission to the forward shock emission, the optical and X-ray lightcurves at t < 3 × 104 s can be well fit adopting a Markov Chain Monte Carlo algorithm. Comparing the properties of GRB 210104A with other GRBs that have detection of bright RS emission, we show that its jet is mildly magnetized (R B = 28), with high radiation efficiency (77%), is subenergetic (E k,iso = 4.5 × 1051 erg), and moderately relativistic (Γ0 ∼ 35) in a density medium (n 0 ∼ 417 cm−3). It follows the tight L γ,iso–E p,z–Γ0 relation as with typical GRBs.

NUMERICAL INVESTIGATION OF THE NANOFLUID NATURAL CONVECTION FLOW IN A CPU HEAT SINK USING BUONGIORNO TOW-PHASE MODEL

In this paper, a numerical investigation using the finite element method on the cooling capacity of an electronic heat sink has been presented. This heat sink is intended for cooling applications of micro-computer CPUs. It deals with a parallelepipedal block with rectangular fins, filled with a nanofluid and crossed by four cylindrical pipes in which a cooling gas flows and dissipates the heat generated by the processor. Indeed, the cooling occurs by three transfers: the first one evacuates the heat from the processor towards the gas, the second one transfers this heat towards the nanofluid and the last one is cooled from the ambient air by means of the fins laterally arranged on the block. From this work, it has been planned to contribute to the study of the behavior of a nanofluid in the heat sink in the presence of a uniform magnetic field in order to enhance the operating and cooling performances. The effects of some control parameters have been highlighted on the hydrodynamic, thermal, and mass behavior of the nanofluid, namely: the Rayleigh number (103 ≤ Ra ≤ 105), the Hartmann number (0 ≤ Ha ≤ 100), the angle of inclination of the magnetic field (0 ≤ γ ≤ 90°) and the nanoparticles diameter (1 nm ≤ dp ≤ 10 nm). On the other hand, a new fin design has been proposed in this study allowing the enhancement of the heat exchange rate with ambient medium. The studied phenomenon is governed by the equations of the two-phase nanofluid model proposed by Buongiorno and which describe the following balances: mass, momentum, energy and nanoparticles. The system of partial differential equations with initial-boundary conditions has been solved by the finite element method. After performing a mesh independence check and validating with previous papers, the results of the investigation were presented. They showed that the application of a magnetic field significantly reduces the rate of heat exchange. However, increasing the angle of inclination of this field promotes convective heat transfer. Moreover, the use of zigzag fins improves the cooling rate by about 4% for amplitude of 0.05 compared to the standard configuration.

Differences in chemical evolution between isolated and embedded prestellar cores

ABSTRACT Models of prestellar cores often assume that the cores are isolated from their environment – material outside the core boundary plays no role in the subsequent evolution. This is unlikely to be the case in reality, where cores are located within hierarchically substructured molecular clouds. We investigate the dynamical and chemical evolution of prestellar cores, modelled as Bonnor–Ebert spheres, and show that the density of the ambient medium has a large impact on the resulting chemical properties of the cores. Models embedded in high-density, low-temperature surroundings have greatly enhanced abundances of several molecules, such as CO and CS, compared to models with more diffuse surroundings, corresponding to relatively isolated cores. The predicted intensities and profile shapes of molecular lines are also affected. The density of the ambient medium has a stronger effect on the chemical evolution than whether the cores are initially in or out of equilibrium. This suggests that the impact of environment cannot be neglected when modelling chemistry in prestellar cores; the results of these models are highly sensitive to the assumptions made about the core surroundings.

Complex nature of the interaction of AFM tip with the freshly splitted (010) surface of CdWO4 and ZnWO4 single crystals

The discovery of new low-dimensional materials formed by splitting known bulk crystals into separate elementary layers has enabled future realization of still undiscovered potential of long-studied materials. High-resistivity two-dimensional films obtained by splitting ionic layered crystals are of great interest for creating new vertical van der Waals heterostructures. For unveiling the potential of using two-dimensional monocrystalline films of CdWO4 and ZnWO4, it is necessary to gain a more penetrating insight into the processes that occur on the freshly splitted surface of the crystals. In the present study, for the first time we investigated the effect of AFM probe on the (010) surfaces of freshly splitted CdWO4 and ZnWO4 single crystals. It is shown that the observed “protruding areas” on the splitted surfaces of these crystals are of a complex nature, and they are mainly related with the transfer of charges, as well as with the formation of complete bonds on the surface of the broken crystal lattice of examined crystals. The charge spots observed on the splitted surface of the crystals arise as a result of local charging by AFM probe. As a result of charge diffusion, as well as under the influence of ambient medium, the complete dissipation of charges occurs in less than 2 h.

Multiple gas phases in supernova remnant IC 443: mapping shocked H2 with VLT/KMOS

ABSTRACT Supernovae and their remnants provide energetic feedback to the ambient interstellar medium (ISM), which is often distributed in multiple gas phases. Among them, warm molecular hydrogen (H2) often dominates the cooling of the shocked molecular ISM, which has been observed with the H2 emission lines at near-infrared wavelengths. Such studies, however, were either limited in narrow filter imaging or sparsely sampled mid-infrared spectroscopic observations with relatively poor angular resolutions. Here we present near-infrared (H and K bands) spectroscopic mosaic observations towards the A, B, C, and G regions of the supernova remnant (SNR) IC 443, with the K-band Multi-Object Spectrograph (KMOS) onboard the Very Large Telescope (VLT). We detected 20 rotational–vibrational transitions of H2, one H line (Brγ), and two [Fe ii] lines, which dominate broad-band images at both H and K bands. The spatial distribution of H2 lines at all regions is clumpy on scales from ∼0.1 down to ∼0.008 pc. The fitted excitation temperature of H2 is between 1500 and 2500 K, indicating warm shocked gas in these regions. The multigas phase comparison shows stratified shock structures in all regions, which explains the coexistence of multiple types of shocks in the same regions. Lastly, we verify the candidates of young stellar objects previously identified in these regions with our spectroscopic data, and find none of them are associated with young stars. This sets challenges to the previously proposed scenario of triggered star formation by SNR shocks in IC 443.

R-process Rain from Binary Neutron Star Mergers in the Galactic Halo

Compact binary mergers involving at least one neutron star are promising sites for the synthesis of the r-process elements found in stars and planets. However, mergers can take place at significant offsets from their host galaxies, with many occurring several kpc from star-forming regions. It is thus important to understand the physical mechanisms involved in transporting enriched material from merger sites in the galactic halo to the star-forming disk. We investigate these processes, starting from an explosive injection event and its interaction with the halo medium. We show that the total outflow mass in compact binary mergers is too low for the material to travel to the disk in a ballistic fashion. Instead, the enriched ejecta is swept into a shell, which decelerates over ≲10 pc scales and becomes corrugated by the Rayleigh–Taylor instability. The corrugated shell is denser than the ambient medium and breaks into clouds that sink toward the disk. These sinking clouds lose thermal energy through radiative cooling, and are also ablated by shearing instabilities. We present a dynamical heuristic that models these effects to predict the delay times for delivery to the disk. However, we find that turbulent mass ablation is extremely efficient and leads to the total fragmentation of sinking r-process clouds over ≲10 pc scales. We thus predict that enriched material from halo injection events quickly assimilates into the gas medium of the halo and that enriched mass flow to the disk could only be accomplished through turbulent diffusion or large-scale inflowing mass currents.

Cosmological Simulation of Galaxy Groups and Clusters. II. Studying Different Modes of Feedback through X-Ray Observations

The impact of feedback from active galactic nuclei (AGNs) on the cosmological evolution of the large-scale structure is a long-studied problem. However, it is still not well understood how the feedback energy couples to the ambient medium to influence the properties of AGN host galaxies and dark matter halos. In this work we investigate different modes of AGN feedback and their effect on the surrounding medium by probing the diffuse X-ray emission from the hot gas inside galaxy groups and clusters. For this purpose, we use the cosmological hydrodynamic simulation SIMBA to theoretically calculate the X-ray emission from simulated galaxy clusters/groups with the help of the Astrophysical Plasma Emission Code. We also perform synthetic observations of these systems with the Chandra X-ray telescope using the ray-tracing simulator Model of AXAF Response to X-rays. Our results show that in addition to the radiative wind mode of feedback from the AGNs, jet and X-ray modes of feedback play significant roles in suppressing the X-ray emission from the diffuse gas in the vicinity of the black hole. Our mock observational maps suggest that the signatures of AGN feedback from high-redshift objects may not be detected with the instrumental resolution of current X-ray telescopes like Chandra, but provide promising prospects for detection of these features with potential X-ray missions such as Lynx.

Experimental and Numerical Validation of Whispering Gallery Resonators as Optical Temperature Sensors.

This study experimentally and numerically validates the commonly employed technique of laser-induced heating of a material in optical temperature sensing studies. Furthermore, the Er3+-doped glass microspheres studied in this work can be employed as remote optical temperature sensors. Laser-induced self-heating is a useful technique commonly employed in optical temperature sensing research when two temperature-dependent parameters can be correlated, such as in fluorescence intensity ratio vs. interferometric calibration, allowing straightforward sensor characterization. A frequent assumption in such experiments is that thermal homogeneity within the sensor volume, that is, a sound hypothesis when dealing with small volume to surface area ratio devices such as microresonators, but has never been validated. In order to address this issue, we performed a series of experiments and simulations on a microsphere supporting whispering gallery mode resonances, laser heating it at ambient pressure and medium vacuum while tracking the resonance wavelength shift and comparing it to the shift rate observed in a thermal bath. The simulations were done starting only from the material properties of the bulk glass to simulate the physical phenomena of laser heating and resonance of the microsphere glass. Despite the simplicity of the model, both measurements and simulations are in good agreement with a highly homogeneous temperature within the resonator, thus validating the laser heating technique.

A Hydro-based MCMC Analysis of SNR 0509−67.5: Revealing the Explosion Properties from Fluid Discontinuities Alone

Using Hubble Space Telescope/ACS Hα images of SNR 0509−67.5 taken ∼10 yr apart, we measure the forward shock (FS) proper motions (PMs) at 231 rim locations. The average shock radius and velocity are 3.66 ± 0.036 pc and 6315 ± 310 km s−1. Hydrodynamic simulations, recast as similarity solutions, provide models for the supernova remnant’s expansion into a uniform ambient medium. These are coupled to a Markov chain Monte Carlo (MCMC) analysis to determine explosion parameters, constrained by the FS measurements. For our baseline model, the MCMC posteriors yield an age of 315.5 ± 1.8 yr, a dynamical explosion center at 5h09m31.ˢ16, and ambient medium densities at each azimuth ranging over 3.7–8.0 × 10−25 g cm−3. The age uncertainty can be an order of magnitude larger when considering other models, or subsets of the data. We detect stellar PMs corresponding to speeds in the Large Magellanic Cloud ≥ 770 km s−1. Five stars in the remnant show measurable PMs but none are moving radially from the dynamical center. There are four stars 1.″4 from the center, including three faint, previously unidentified ones. Using coronal [Fe xiv] λ5303 emission as a proxy for the reverse shock location, we constrain the explosion energy (for a compression factor of 4) to a value of E = (1.30 ± 0.41) × 1051 erg for the first time from shock kinematics alone. Higher compression factors (7 or more) are strongly disfavored based on multiple criteria, arguing for inefficient particle acceleration in the Balmer shocks of SNR 0509−67.5.

Simulation of Thermal Processes under Variable Boundary Conditions in a Multilayer Thin Wall: A Man–Woven Electric Heater–Ambient Medium

Simulation of Thermal Processes under Variable Boundary Conditions in a Multilayer Thin Wall: A Man–Woven Electric Heater–Ambient Medium

Prompt Emission of γ-Ray Bursts in the High-density Environment of Active Galactic Nucleus Accretion Disks

Long and short γ-ray bursts (GRBs) are traditionally associated with galactic environments, where circumburst densities are small or moderate (few to hundreds of protons per cubic centimeter). However, both are also expected to occur in the disks of active galactic nuclei, where the ambient medium density can be much larger. In this work we study, via semianalytical methods, the propagation of the GRB outflow, its interaction with the external material, and the ensuing prompt radiation. In particular, we focus on the case in which the external shock develops early in the evolution at a radius that is smaller than the internal shock one. We find that bursts in such high-density environments are likely characterized by a single, long emission episode that is due to the superposition of individual pulses, with a characteristic hard-to-soft evolution irrespective of the light-curve luminosity. While multipulse light curves are not impossible, they would require the central engine to go dormant for a long time before reigniting. In addition, short GRB engines would produce bursts with prompt duration that would exceed the canonical 2 s separation threshold and likely be incorrectly classified as long events, even though they would not be accompanied by a simultaneous supernova. Finally, these events have a large dynamical efficiency, which would produce a bright prompt emission followed by a somewhat dim afterglow.

Wälzfestigkeit maschinell gehämmerter Oberflächenstrukturen im Zahnflankenanalogieversuch

Rolling-sliding contacts, such as the tooth flank contact, are tribological systems whose properties are determined by the interactions between the contacting bodies, the lubricant and the ambient medium. Innovative manufacturing processes are being used to reduce friction and increase the load-carrying capacity of highly loaded rolling-sliding contacts. For mixed friction conditions, bowl-shaped structures in particular, generated for example by laser machining, have led to improved running behavior. Similar to laser machining, machine hammer peening (MHP) also produces a deterministic surface structure that can exhibit improved tribological properties. In recent years, MHP has been used specifically to optimize the service life of highly stressed tools, e.g. in deep-drawing processes, and has been developed further in a targeted manner. In this report, the rolling strength of machine-hammered surfaces is evaluated using fatigue tests on a disk-on-disk test rig gear-typical contact conditions. The MHP can be used to increase the contact strength in a targeted manner, whereby the selection of the process parameters during surface hammering represent an important influencing factor. In particular, the surface can be pre-damaged by excessive impact energy as a result of the ram stroke.

S-type fiber surface plasmon resonance strain sensor.

The fiber surface plasmon resonance (SPR) sensor is widely used in high-sensitivity refractive index detection, and there are few reports on SPR sensors used for strain measurement. In this paper, we propose and demonstrate an S-type fiber strain sensor based on SPR. The simulation and testing results indicate that the smaller the vertical axis offset of S-type fiber is, the larger the incidence angle of SPR is, and the closer the working band of SPR is to the shorter wavelength direction. By electrofusion, we fabricated an S-type structure on the single-mode fiber, and by the S-type structure, the high-order cladding mode was excited. A 50 nm gold film was coated on the surface of the fiber cladding behind the S-type structure. The evanescent field of the cladding mode contacted the gold film to produce SPR, and the strain can change the vertical axis offset of the S-type fiber and further change the incidence angle of SPR; hence an S-type fiber strain sensor based on SPR was realized. When the refractive index of the ambient medium is 1.345 RIU, the vertical axis offset and length of the S-shaped structure are 87 and 501 µm, respectively, the resonance wavelength of the fiber SPR strain sensor changes from 648.06 to 631.77 nm with a strain detection range of 0-1200µε, and its sensitivity is -14.38pm/µε. The proposed sensor provides a new solution for the strain measurement of the fiber SPR sensor, which is expected to be used in the fields of engineering, health monitoring, and early warning.

Effect of the Heliospheric State on CME Evolution

The culmination of solar cycle 24 by the end of 2019 has created the opportunity to compare the differing properties of coronal mass ejections (CMEs) between two whole solar cycles: solar cycle 23 (SC 23) and solar cycle 24 (SC 24). We report on the width evolution of limb CMEs in SCs 23 and 24 in order to test the suggestion by Gopalswamy et al. that CME flux ropes attain pressure balance at larger heliocentric distances in SC 24. We measure CME width as a function of heliocentric distance for a significantly large number of limb CMEs (∼1000) and determine the distances where the CMEs reach constant width in each cycle. We introduced a new parameter, the transition height (hc) of a CME, defined as the critical heliocentric distance beyond which the CME width stabilizes to a quasi-constant value. Cycle and phase-to-phase comparisons are based on this new parameter. We find that the average value of hc in SC 24 is 62% higher than that in SC 23. SC 24 CMEs attain their peak width at larger distances from the Sun than SC 23 CMEs do. The enhanced transition height in SC 24 is new observational ratification of the anomalous expansion. The anomalous expansion of SC 24 CMEs, which is caused by the weak state of the heliosphere, accounts for the larger heliocentric distance where the pressure balance between CME flux rope and the ambient medium is attained.

The Spiderweb Protocluster is Being Magnetized by Its Central Radio Jet

We present deep broadband radio polarization observations of the Spiderweb radio galaxy (J1140-2629) in a galaxy protocluster at z = 2.16. These yield the most detailed polarimetric maps yet made of a high-redshift radio galaxy. The intrinsic polarization angles and Faraday rotation measures (RMs) reveal coherent magnetic fields spanning the ∼60 kpc length of the jets, while ∼50% fractional polarizations indicate these fields are well ordered. Source-frame ∣RM∣ values of ∼1000 rad m−2 are typical, and values up to ∼11,100 rad m−2 are observed. The Faraday-rotating gas cannot be well mixed with the synchrotron-emitting gas, or stronger-than-observed depolarization would occur. Nevertheless, an observed spatial coincidence between a localized ∣RM∣ enhancement of ∼1100 rad m−2 , a bright knot of Lyα emission, and a deviation of the radio jet provide direct evidence for vigorous jet-gas interaction. We detect a large-scale RM gradient totaling ∼1000 s rad m−2 across the width of the jet, suggesting a net clockwise (as viewed from the active galactic nuclei) toroidal magnetic field component exists at tens-of-kiloparsec scales, which we speculate may be associated with the operation of a Poynting–Robertson cosmic battery. We conclude the RMs are mainly generated in a sheath of hot gas around the radio jet, rather than the ambient foreground protocluster gas. The estimated magnetic field strength decreases by successive orders of magnitude going from the jet hotspots (∼90 μG) to the jet sheath (∼10 μG) to the ambient intracluster medium (∼1 μG). Synthesizing our results, we propose that the Spiderweb radio galaxy is actively magnetizing its surrounding protocluster environment, with possible implications for theories of the origin and evolution of cosmic magnetic fields.

T-matrix simulations of the optical response of gold nanorods: Impact of dielectric function of nanorods on the simulated optical properties and their sensitivity to the dielectric environment

The T-matrix approach is used to elucidate the influence of the dielectric function of gold nanorods on their optical response. On the basis of extensive and systematic numerical simulations, we follow the spectral variations of extinction efficiency and field enhancement as a function of the nanorod’s dielectric properties, medium dielectric constant, and aspect ratio. Simulations with six available tabulated gold dielectric functions show different locations of the longitudinal localized surface plasmon resonance (LSPR). A shift of up to 50 nm is found and compared with experimental data available in the literature. With the increasing refractive index of the ambient medium, the peaks red shift to higher wavelengths, which can be understood in terms of the reduced plasmon energy due to the reduced restoring forces of the plasmon oscillations. A linear correlation exists between the relative shift of the resonance wavelength and the relative increment of the medium refractive index. The correlation coefficient represents the sensitivity of the resonance to the dielectric environment and is more dependent on the aspect ratio than the dielectric properties of nanorods. However, a non-linear correlation is observed between the relative changes in the resonance extinction peak and the relative refractive index increment of the medium, which is considerably affected by the dielectric properties of nanorods. Results reveal that the field enhancement is influenced primarily by the dielectric environment and the aspect ratio. Simulations with the size-corrected dielectric functions show a broadening of the LSPR with no significant shift, in addition to a reduced extinction efficiency and field enhancement.

Finite-amplitude instability of the buoyancy boundary layer in a thermally stratified medium

The finite-amplitude instability of the buoyancy-driven boundary layer is considered on a vertical plate immersed in a thermally stratified ambient medium, where the wall and surrounding fluid have different temperature gradients. Although the linear stability in this configuration has been investigated, the finite-amplitude solution arising from the critical instability has been studied only for specific parameter values. We extend this by using the amplitude expansion method. The primary bifurcations to the two-dimensional least unstable mode for different temperature gradient ratios ( $0 \leqslant \lambda \leqslant 10$ ) and Prandtl numbers ( $10^{-1} \leqslant Pr \leqslant 10^{4}$ ) are investigated. Only supercritical bifurcations are found to occur when $0 \leqslant \lambda &lt; 2$ and $Pr \leqslant 2800$ , while subcritical bifurcations are also found for larger values of temperature gradient ratio and Prandtl number. Analysis of the contribution of the nonlinear terms in the Landau coefficient reveals that the interaction of the modification of the mean flow and second harmonic for velocity with the fundamental mode for temperature plays an important role in subcritical bifurcation. Based on the Landau equation, the threshold amplitude of the nonlinear equilibrium solution is discussed as well. These encouraging results should be helpful for understanding such a buoyancy-driven flow system.

Bridging the Bondi and Event Horizon Scales: 3D GRMHD Simulations Reveal X-shaped Radio Galaxy Morphology

X-shaped radio galaxies (XRGs) produce misaligned X-shaped jet pairs and make up ≲10% of radio galaxies. XRGs are thought to emerge in galaxies featuring a binary supermassive black hole (SMBH), SMBH merger, or large-scale ambient medium asymmetry. We demonstrate that XRG morphology can naturally form without such special, preexisting conditions. Our 3D general-relativistic magnetohydrodynamic (GRMHD) simulation for the first time follows magnetized rotating gas from outside the SMBH sphere of influence of radius R B to the SMBH of gravitational radius R g at the largest scale separation, R B/R g = 103, to date. Initially, our axisymmetric system of constant-density hot gas contains a weak vertical magnetic field and rotates in the equatorial plane of a rapidly spinning SMBH. We seed the gas with small-scale 2% level pressure perturbations. Infalling gas forms an accretion disk, and the SMBH launches relativistically magnetized collimated jets reaching well outside R B. Under the pressure of the infalling gas, the jets intermittently turn on and off, erratically wobble, and inflate pairs of cavities in different directions, resembling an X-shaped jet morphology. Synthetic X-ray images reveal multiple pairs of jet-powered shocks and cavities. Large-scale magnetic flux accumulates on the SMBH, becomes dynamically important, and leads to a magnetically arrested disk state. The SMBH accretes at 2% of the Bondi rate ( for M87*) and launches twin jets at η = 150% efficiency. These jets are powerful enough (P jets ≃ 2 × 1044 erg s−1) to escape along the SMBH spin axis and end the short-lived intermittent jet state, whose transient nature can account for the rarity of XRGs.