arXiv subjects

Debora Sijacki

Publications and source records attributed to Debora Sijacki.

At least 55 records · Page 3Linked to original sources

arXiv2023

The Pandora project. I: the impact of radiation and cosmic rays on baryonic and dark matter properties of dwarf galaxies

Enshrouded in several well-known controversies, dwarf galaxies have been extensively studied to learn about the underlying cosmology, notwithstanding that physical processes regulating their properties are poorly understood. To shed light on these processes, we introduce the Pandora suite of 17 high-resolution (3.5 parsec half-cell side) dwarf galaxy formation cosmological simulations. Commencing with thermo-turbulent star formation and mechanical supernova feedback, we gradually increase the complexity of physics incorporated leading to full-physics models combining magnetism, on-the-fly radiative transfer and the corresponding stellar photoheating, and SN-accelerated cosmic rays. We investigate combinations of these processes, comparing them with observations to constrain what are the main mechanisms determining dwarf galaxy properties. We find hydrodynamical `SN feedback-only' simulations struggle to produce realistic dwarf galaxies, leading either to overquenched or too centrally concentrated, dispersion dominated systems when compared to observed field dwarfs. Accounting for radiation with cosmic rays results in extended and rotationally-supported systems. Spatially `distributed' feedback leads to realistic stellar and HI masses as well as kinematics. Furthermore, resolved kinematic maps of our full-physics models predict kinematically distinct clumps and kinematic misalignments of stars, HI and HII after star formation events. Episodic star formation combined with its associated feedback induces more core-like dark matter central profiles, which our `SN feedback-only' models struggle to achieve. Our results demonstrate the complexity of physical processes required to capture realistic dwarf galaxy properties, making tangible predictions for integral field unit surveys, radio synchrotron emission, and for galaxy and multi-phase interstellar medium properties that JWST will probe.

astro-ph.GA↗

arXiv2023

The impact of cosmic rays on the interstellar medium and galactic outflows of Milky Way analogues

During the last decade, cosmological simulations have managed to reproduce realistic and morphologically diverse galaxies, spanning the Hubble sequence. Central to this success was a phenomenological calibration of the few included feedback processes, whilst glossing over higher complexity baryonic physics. This approach diminishes the predictive power of such simulations, preventing to further our understanding of galaxy formation. To tackle this fundamental issue, we investigate the impact of cosmic rays (CRs) and magnetic fields on the interstellar medium (ISM) and the launching of outflows in a cosmological zoom-in simulation of a Milky Way-like galaxy. We find that including CRs decreases the stellar mass of the galaxy by a factor of 10 at high redshift and $\sim 4$ at cosmic noon, leading to a stellar mass to halo mass ratio in good agreement with abundance matching models. Such decrease is caused by two effects: i) a reduction of cold, high-density, star-forming gas, and ii) a larger fraction of SN events exploding at lower densities, where they have a higher impact. SN-injected CRs produce enhanced, multi-phase galactic outflows, which are accelerated by CR pressure gradients in the circumgalactic medium of the galaxy. While the mass budget of these outflows is dominated by the warm ionised gas, warm neutral and cold gas phases contribute significantly at high redshifts. Importantly, our work shows that future JWST observations of galaxies and their multi-phase outflows across cosmic time have the ability to constrain the role of CRs in regulating star formation.

astro-ph.GA↗

arXiv2022

Shattering and growth of cold clouds in galaxy clusters: the role of radiative cooling, magnetic fields and thermal conduction

In galaxy clusters, the hot intracluster medium (ICM) can develop a striking multi-phase structure around the brightest cluster galaxy. Much work has been done on understanding the origin of this central nebula, but less work has studied its eventual fate after the originally filamentary structure is broken into individual cold clumps. In this paper we perform a suite of 30 (magneto-)hydrodynamical simulations of kpc-scale cold clouds with typical parameters as found by galaxy cluster simulations, to understand whether clouds are mixed back into the hot ICM or can persist. We investigate the effects of radiative cooling, small-scale heating, magnetic fields, and (anisotropic) thermal conduction on the long-term evolution of clouds. We find that filament fragments cool on timescales shorter than the crushing timescale, fall out of pressure equilibrium with the hot medium, and shatter, forming smaller clumplets. These act as nucleation sites for further condensation, and mixing via Kelvin-Helmholtz instability, causing cold gas mass to double within 75 Myr. Cloud growth depends on density, as well as on local heating processes, which determine whether clouds undergo ablation- or shattering-driven evolution. Magnetic fields slow down but don't prevent cloud growth, with the evolution of both cold and warm phase sensitive to the field topology. Counter-intuitively, anisotropic thermal conduction increases the cold gas growth rate compared to non-conductive clouds, leading to larger amounts of warm phase as well. We conclude that dense clumps on scales of $500$ pc or more cannot be ignored when studying the long-term cooling flow evolution of galaxy clusters.

astro-ph.GA↗

arXiv2022

Two can play at that game: constraining the role of supernova and AGN feedback in dwarf galaxies with cosmological zoom-in simulations

There is growing observational evidence for dwarf galaxies hosting active galactic nuclei (AGN), including hints of AGN-driven outflows in dwarfs. However, in the common theoretical model of galaxy formation, efficient supernova (SN) feedback is the tool of choice for regulating star formation in the low-mass regime. In this paper, we present a suite of high-resolution cosmological dwarf zoom-in simulations relaxing the assumption of strong SN feedback, with the goal to determine whether more moderate SN feedback in combination with an efficient AGN could be a suitable alternative. Importantly, we find that there are sufficient amounts of gas to power brief Eddington-limited accretion episodes in dwarfs. This leads to a variety of outcomes depending on the AGN accretion model: from no additional suppression to moderate regulation of star formation to catastrophic quenching. Efficient AGN can drive powerful outflows, depleting the gas reservoir of their hosts via ejective feedback and then maintaining a quiescent state through heating the circumgalactic medium. Moderate AGN outflows can be as efficient as the strong SN feedback commonly employed, leading to star formation regulation and HI gas masses in agreement with observations of field dwarfs. All efficient AGN set-ups are associated with overmassive black holes (BHs) compared to the (heavily extrapolated) observed BH mass - stellar mass scaling relations, with future direct observational constraints in this mass regime being crucially needed. Efficient AGN activity is mostly restricted to high redshifts, with hot, accelerated outflows and high X-ray luminosities being the clearest tell-tale signs for future observational campaigns.

astro-ph.GA↗

arXiv2022

Blandford-Znajek jets in galaxy formation simulations: exploring the diversity of outflows produced by spin-driven AGN jets in Seyfert galaxies

Recent observations of Seyfert galaxies indicate that low power, misaligned jets can undergo significant interaction with the gas in the galactic disc and may be able to drive large-scale, multiphase outflows. We apply our novel sub-grid model for Blandford-Znajek jets to simulations of the central regions of Seyferts, in which a black hole is embedded in a dense, sub-kpc circumnuclear disc (CND) and surrounded by a dilute circumgalactic medium (CGM). We find that the variability of the accretion flow is highly sensitive both to the jet power and to the CND thermodynamics and, ultimately, is determined by the complex interplay between jet-driven outflows and backflows. Even at moderate Eddington ratios, AGN jets are able to significantly alter the thermodynamics and kinematics of CNDs and entrain up to 10% of their mass in the outflow. Mass outflow rates and kinetic powers of the warm outflowing component are in agreement with recent observations for black holes with similar bolometric luminosities, with outflow velocities that are able to reach 500 km/s. Depending on their power and direction, jets are able to drive a wide variety of large-scale outflows, ranging from light, hot and collimated structures to highly mass-loaded, multiphase, bipolar winds. This diversity of jet-driven outflows highlights the importance of applying physically motivated models of AGN feedback to realistic galaxy formation contexts. Such simulations will play a crucial role in accurately interpreting the wealth of data that next generation facilities such as JWST, SKA and Athena will provide.

astro-ph.GA↗

arXiv2022

A disturbing FABLE of mergers, feedback, turbulence, and mass biases in simulated galaxy clusters

The use of galaxy clusters as cosmological probes often relies on understanding the properties and evolution of the intracluster medium (ICM). However, the ICM is a complex plasma, regularly stirred by mergers and feedback, with non-negligible bulk and turbulent motions and a non-thermal pressure component, making it difficult to construct a coherent and comprehensive picture. To this end, we use the FABLE simulations to investigate how the hydrostatic mass bias is affected by mergers, turbulence, and feedback. Following in detail a single, massive cluster we find the bias varies significantly over cosmic time, rarely staying at the average value found at a particular epoch. Variations of the bias at a given radius are contemporaneous with periods where outflows dominate the mass flux, either due to mergers or interestingly, at high redshift, AGN feedback. The $z=0$ ensemble median mass bias in FABLE is $\sim\!13$ per cent at $R_\mathrm{500}$ and $\sim\!15$ per cent at $R_\mathrm{200}$, but with a large scatter in individual values. In halo central regions, we see an increase in temperature and a decrease in non-thermal pressure support with cosmic time as turbulence thermalises, leading to a reduction in the mass bias within $\sim\!0.2 \, R_\mathrm{200}$. When using a fitted pressure profile, instead of the simulation data, to estimate the bias, we find there can be significant differences, particularly at larger radii and higher redshift. We therefore caution over the use of such fits in future work when comparing with the next generation of X-ray and SZ observations.

astro-ph.GA↗

arXiv2022

Towards convergence of turbulent dynamo amplification in cosmological simulations of galaxies

Our understanding of the process through which magnetic fields reached their observed strengths in present-day galaxies remains incomplete. One of the advocated solutions is a turbulent dynamo mechanism that rapidly amplifies weak magnetic field seeds to the order of ${\sim}μ$G. However, simulating the turbulent dynamo is a very challenging computational task due to the demanding span of spatial scales and the complexity of the required numerical methods. In particular, turbulent velocity and magnetic fields are extremely sensitive to the spatial discretisation of simulated domains. To explore how refinement schemes affect galactic turbulence and amplification of magnetic fields in cosmological simulations, we compare two refinement strategies. A traditional quasi-Lagrangian adaptive mesh refinement approach focusing spatial resolution on dense regions, and a new refinement method that resolves the entire galaxy with a high resolution quasi-uniform grid. Our new refinement strategy yields much faster magnetic energy amplification than the quasi-Lagrangian method, which is also significantly greater than the adiabatic compressional estimate indicating that the extra amplification is produced through stretching of magnetic field lines. Furthermore, with our new refinement the magnetic energy growth factor scales with resolution following $\propto \Dres^{-1/2}$, in much better agreement with small-scale turbulent box simulations. Finally, we find evidence suggesting most magnetic amplification in our simulated galaxies occurs in the warm phase of their interstellar medium, which has a better developed turbulent field with our new refinement strategy.

astro-ph.GA↗

arXiv2021

Momentum deposition of supernovae with cosmic rays

The cataclysmic explosions of massive stars as supernovae are one of the key ingredients of galaxy formation. However, their evolution is not well understood in the presence of magnetic fields or cosmic rays (CRs). We study the expansion of individual supernova remnants (SNRs) using our suite of 3D hydrodynamical (HD), magnetohydrodynamical (MHD) and CRMHD simulations generated using RAMSES. We explore multiple ambient densities, magnetic fields and fractions of supernova energy deposited as CRs ($χ_{\rm CR}$), accounting for cosmic ray anisotropic diffusion and streaming. All our runs have comparable evolutions until the end of the Sedov-Taylor phase. However, our CRMHD simulations experience an additional CR pressure-driven snowplough phase once the CR energy dominates inside the SNR. We present a model for the final momentum deposited by supernovae that captures this new phase: $p_{\rm SNR} = 2.87\times 10^{5} (χ_{\text{CR}} + 1)^{4.82}\left(\frac{n}{\text{cm}^{-3}}\right)^{-0.196} M_{\odot}$ km s$^{-1}$. Assuming a 10% fraction of SN energy in CRs leads to a 50% boost of the final momentum, with our model predicting even higher impacts at lower ambient densities. The anisotropic diffusion of CRs assuming an initially uniform magnetic field leads to extended gas and cosmic ray outflows escaping from the supernova poles. We also study a tangled initial configuration of the magnetic field, resulting instead in a quasi-isotropic diffusion of CRs and earlier momentum deposition. Finally, synthetic synchrotron observations of our simulations using the POLARIS code show that the local magnetic field configuration in the interstellar medium modifies the overall radio emission morphology and polarisation.

astro-ph.GA↗

arXiv2021

Morphological evolution of supermassive black hole merger hosts and multimessenger signatures

With projects such as Laser Interferometer Space Antenna (LISA) and Pulsar Timing Arrays expected to detect gravitational waves from supermassive black hole mergers in the near future, it is key that we understand what we expect those detections to be, and maximize what we can learn from them. To address this, we study the mergers of supermassive black holes in the Illustris simulation, the overall rate of mergers, and the correlation between merging black holes and their host galaxies. We find that these mergers occur in typical galaxies along the $M_{\rm{BH}}-M_*$ relation, and that between LISA and PTAs we expect to probe the full range of galaxy masses. As galaxy mergers can trigger increased star formation, we find that galaxies hosting low-mass black hole mergers tend to show a slight increase in star formation rates compared to a mass-matched sample. However, high-mass merger hosts have typical star formation rates, due to a combination of low gas fractions and powerful AGN feedback. Although minor black hole mergers do not correlate with disturbed morphologies, major mergers (especially at high-masses) tend to show morphological evidence of recent galaxy mergers which survives for ~500 Myr. This is on the same scale as the infall/hardening time of the merging black holes, suggesting that electromagnetic followups to gravitational wave signals may not be able to observe this correlation. We further find that incorporating a realistic timescale delay for the black hole mergers could shift the distribution of merger masses toward higher-masses, decreasing the rate of LISA detections while increasing the rate of PTA detections.

astro-ph.GA↗

arXiv2021

Blandford-Znajek jets in galaxy formation simulations: method and implementation

Jets launched by active galactic nuclei (AGN) are believed to play a significant role in shaping the properties of galaxies and provide an energetically viable mechanism through which galaxies can become quenched. Here we present a novel AGN feedback model, which we have incorporated into the AREPO code, that evolves the black hole mass and spin as the accretion flow proceeds through a thin $α$-disc which we self-consistently couple to a Blandford-Znajek jet. We apply our model to the central region of a typical radio-loud Seyfert galaxy embedded in a hot circumgalactic medium (CGM). We find that jets launched into high pressure environments thermalise efficiently due to the formation of recollimation shocks and the vigorous instabilities that these shocks excite increase the efficiency of the mixing of CGM and jet material. The beams of more overpressured jets, however, are not as readily disrupted by instabilities so the majority of the momentum flux at the jet base is retained out to the head, where the jet terminates in a reverse shock. All jets entrain a significant amount of cold circumnuclear disc material which, while energetically insignificant, dominates the lobe mass together with the hot, entrained CGM material. The jet power evolves significantly due to effective self-regulation by the black hole, fed by secularly-driven, intermittent mass flows. The direction of jets launched directly into the circumnuclear disc changes considerably due to effective Bardeen-Petterson torquing. Interestingly, these jets obliterate the innermost regions of the disc and drive large-scale, multi-phase, turbulent, bipolar outflows.

astro-ph.GA↗

arXiv2021

Cosmological simulations of massive black hole seeds: predictions for next generation electromagnetic and gravitational wave observations

We study how statistical properties of supermassive black holes depend on the frequency and conditions for massive seed formation in cosmological simulations of structure formation. We develop a novel method to recalculate detailed growth histories and merger trees of black holes within the framework of the Illustris simulation for several seed formation models, including a physically motivated model where black hole seeds only form in progenitor galaxies that conform to the conditions for direct collapse black hole formation. While all seed models considered here are in a broad agreement with present observational constraints on black hole populations from optical, UV and X-ray studies, we find that they lead to widely different black hole number densities and halo occupation fractions which are currently observationally unconstrained. In terms of future electromagnetic spectrum observations, the faint-end quasar luminosity function and the low-mass-end black hole-host galaxy scaling relations are very sensitive to the specific massive seed prescription. Specifically, the direct collapse model exhibits a seeding efficiency which decreases rapidly with cosmic time and produces much fewer black holes in low mass galaxies, in contrast to the original Illustris simulation. We further find that the total black hole merger rate varies by more than one order of magnitude for different seed models, with the redshift evolution of the chirp mass changing as well. Supermassive black hole merger detections with LISA and International Pulsar Timing Array may hence provide the most direct means of constraining massive black hole seed formation in the early Universe.

astro-ph.GA↗

arXiv2021

Unraveling the origin of magnetic fields in galaxies

Despite their ubiquity, there are many open questions regarding galactic and cosmic magnetic fields. Specifically, current observational constraints cannot rule out if magnetic fields observed in galaxies were generated in the Early Universe or are of astrophysical nature. Motivated by this we use our magnetic tracers algorithm to investigate whether the signatures of primordial magnetic fields persist in galaxies throughout cosmic time. We simulate a Milky Way-like galaxy in four scenarios: magnetised solely by primordial magnetic fields, magnetised exclusively by SN-injected magnetic fields, and two combined primordial + SN magnetisation cases. We find that once primordial magnetic fields with a comoving strength $B_0 >10^{-12}$ G are considered, they remain the primary source of galaxy magnetisation. Our magnetic tracers show that, even combined with galactic sources of magnetisation, when primordial magnetic fields are strong, they source the large-scale fields in the warm metal-poor phase of the simulated galaxy. In this case, the circumgalactic and intergalactic medium can be used to probe $B_0$ without risk of pollution by magnetic fields originated in the galaxy. Furthermore, whether magnetic fields are primordial or astrophysically-sourced can be inferred by studying local gas metallicity. As a result, we predict that future state-of-the-art observational facilities of magnetic fields in galaxies will have the potential to unravel astrophysical and primordial magnetic components of our Universe.

astro-ph.GA↗

arXiv2021

AGN jet feedback on a moving mesh: gentle cluster heating by weak shocks and lobe disruption

While there is overwhelming observational evidence of AGN-driven jets in galaxy clusters and groups, if and how the jet energy is delivered to the ambient medium remains unanswered. Here we perform very high resolution AGN jet simulations within a live, cosmologically evolved cluster with the moving mesh code AREPO. We find that mock X-ray and radio lobe properties are in good agreement with observations with different power jets transitioning from FR-I to FR-II-like morphologies. During the lobe inflation phase, heating by both internal and bow shocks contributes to lobe energetics, and $\sim 40$ per cent of the feedback energy goes into the $PdV$ work done by the expanding lobes. Low power jets are more likely to simply displace gas during lobe inflation, but higher power jets become more effective at driving shocks and heating the intracluster medium (ICM), although shocks rarely exceed $\mathcal{M}\sim 2-3$. Once the lobe inflation phase ceases, cluster weather significantly impacts the lobe evolution. Lower power jet lobes are more readily disrupted and mixed with the ICM, depositing up to $\sim 70$ per cent of the injected energy, however, ultimately the equivalent of $\gtrsim 50$ per cent of the feedback energy ends up as potential energy of the system. Even though the mean ICM entropy is increased up to $80$~Myr after the jets switch off, AGN heating is gentle, inducing no large variations in cluster radial profiles in accord with observations.

astro-ph.HE↗

arXiv2021

A little FABLE: exploring AGN feedback in dwarf galaxies with cosmological simulations

Contrary to the standard lore, there is mounting observational evidence that feedback from active galactic nuclei (AGN) may also play a role at the low-mass end of the galaxy population. We investigate this using the cosmological simulation suite FABLE, with a particular focus on the dwarf regime ($M_\mathrm{stellar} < 10^{9.5} \ \mathrm{M_{\odot}}$). We find that overmassive black holes (BHs), with respect to the mean scaling relations with their host galaxies, drive hotter and faster outflows and lead to significantly reduced gas mass fractions. They are also more likely to display a kinematically misaligned ionized gas component in our mock MaNGA velocity maps, although we caution that cosmic inflows and mergers contribute to misalignments as well. While in the local Universe the majority of AGN in dwarfs are much dimmer than the stellar component, for $z \geq 2$ there is a significant population that outshines their hosts. These high-redshift overmassive BHs contribute to the quenching of dwarfs, whereas at late cosmic times supernova (SN) feedback is more efficient. While our results are overall in good agreement with X-ray observations of AGN in dwarfs, the lack of high-luminosity X-ray AGN in FABLE at low redshifts highlights an interesting possibility that SN feedback could be too strong in FABLE's dwarfs, curtailing AGN growth and feedback. We predict that future observations may uncover many more AGN in dwarfs with lower luminosities and at higher redshifts.

astro-ph.GA↗

arXiv2020

Resolving shocks and filaments in galaxy formation simulations: effects on gas properties and star formation in the circumgalactic medium

There is an emerging consensus that large amounts of gas do not shock heat in the circumgalactic medium (CGM) of massive galaxies, but instead pierce deep into haloes from the cosmic web via filaments. To better resolve this process numerically, we have developed a novel `shock refinement' scheme within the moving mesh code AREPO that adaptively improves resolution around shocks on-the-fly in galaxy formation simulations. We apply this to a massive $\sim10^{12}$ M$_\odot$ halo at $z=6$ using the successful FABLE model, increasing the mass resolution by a factor of 512. With better refinement there are significantly more dense, metal-poor and fast-moving filaments and clumps flowing into the halo, leading to a more multiphase CGM. We find a $\sim50$ per cent boost in cool-dense gas mass and a 25 per cent increase in inflowing mass flux. Better resolved accretion shocks cause turbulence to increase dramatically, leading to a doubling in the halo's non-thermal pressure support. Despite much higher thermalisation at shocks with higher resolution, increased cooling rates suppress the thermal energy of the halo. In contrast, the faster and denser filaments cause a significant jump in the bulk kinetic energy of cool-dense gas, while in the hot phase turbulent energy increases by up to $\sim150$ per cent. Moreover, HI covering fractions within the CGM increase by up to 60 per cent. Consequently star formation is spread more widely and we predict a population of metal-poor stars forming within primordial filaments that deep JWST observations may be able to probe.

astro-ph.GA↗

arXiv2020

The baryon content of groups and clusters of galaxies in the FABLE simulations

We study the gas and stellar mass content of galaxy groups and clusters in the FABLE suite of cosmological hydrodynamical simulations, including the evolution of their central brightest cluster galaxies (BCGs), satellite galaxies and intracluster light (ICL). The total gas and stellar mass of FABLE clusters are in very good agreement with observations and show negligible redshift evolution at fixed halo mass for $M_{500} \gtrsim 3 \times 10^{14} M_{\odot}$ at $z \lesssim 1$, in line with recent findings from Sunyaev-Zel'dovich (SZ)-selected cluster samples. Importantly, the simulations predict significant redshift evolution in these quantities in the low mass ($M_{500} \sim 10^{14} M_{\odot}$) regime, which will be testable with upcoming SZ surveys such as SPT-3G. While the stellar masses of FABLE BCGs are in reasonable agreement with observations, the total stellar mass in satellite galaxies is lower than observed and the total mass in ICL is somewhat higher. This may be caused by enhanced tidal stripping of satellite galaxies due to their large sizes. BCGs are characterised by moderate stellar mass growth at $z < 1$ coincident with a late-time development of the ICL. The level of BCG mass growth is in good agreement with recent observations, however, we caution that the inferred growth depends sensitively on the mass definition. We further show that in-situ star formation contributes more than half the mass of a BCG over its lifetime, the bulk of which is gained at $z > 1$ where star formation rates are highest. The stellar mass profiles of the BCG+ICL component are similar to observed profiles out to $\sim 100$ kpc at $z \approx 0$ and follow a close to power law shape out to several hundred kpc. We further demonstrate that the inferred size growth of BCGs can be severely biased by the choice of parametric model and the outer radius of the fit.

astro-ph.GA↗

arXiv2020

Metal enrichment in the circumgalactic medium and Lyα haloes around quasars at z $\sim$3

Deep observations have detected extended Ly$α$ emission nebulae surrounding tens of quasars at redshift 2 to 6. However, the metallicity of such extended haloes is still poorly understood. We perform a detailed analysis on a large sample of 80 quasars at $z\sim3$ based on MUSE-VLT data. We find clear evidence of extended emission of the UV nebular lines such as CIV or HeII for about 20$\%$ of the sample, while CIII] is only marginally detected in a few objects. By stacking the cubes we detect emission of CIV, HeII and CIII] out to a radius of about 45 kpc. CIV and HeII show a radial decline much steeper than Ly$α$, while CIII] shows a shallower profile similar to Ly$α$ in the inner 45 kpc. We infer that the average metallicity of the circumgalactic gas within the central 30-50~kpc is $\sim$0.5 solar, or even higher. However, we also find evidence of a component of the Ly$α$ haloes, which has much weaker metal emission lines relative to Ly$α$. We suggest that the high metallicity of the circumgalactic medium within the central 30-50 kpc is associated with chemical pre-enrichment by past quasar-driven outflows and that there is a more extended component of the CGM that has much lower metallicity and likely associated with near-pristine gas accreted from the intergalactic medium. We show that our observational results are in good agreement with the expectations of the FABLE zoom-in cosmological simulations.

astro-ph.GA↗

arXiv2019

AGN jet feedback on a moving mesh: lobe energetics and X-ray properties in a realistic cluster environment

Jet feedback from active galactic nuclei (AGN) harboured by brightest cluster galaxies is expected to play a fundamental role in regulating cooling in the intracluster medium (ICM). While observations and theory suggest energy within jet lobes balances ICM radiative losses, the modus operandi of energy communication with the ICM remains unclear. We present simulations of very high resolution AGN-driven jets launching in a live, cosmological galaxy cluster, within the moving mesh code AREPO. As the jet propagates through the ICM the majority of its energy, which is initially in the kinetic form, thermalizes quickly through internal shocks and inflates lobes of very hot gas. The jets effectively heat the cluster core, with $PdV$ work and weather-aided mixing being the main channels of energy transfer from the lobes to the ICM, while strong shocks and turbulence are subdominant. We additionally present detailed mock X-ray maps at different stages of evolution, revealing clear cavities surrounded by X-ray bright rims, with lobes being detectable for up to $\sim 10^8$ yr even when magnetic draping is ineffective. We find bulk motions in the cluster can significantly affect lobe propagation, offsetting them from the jet direction and imparting bulk velocities that can dominate over the buoyantly rising motion.

astro-ph.GA↗