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M. Tartėnas

Publications and source records attributed to M. Tartėnas.

3 recordsLinked to original sources

Low-power jet-ISM coupling and disk-plane perturbations in the edge-on Seyfert galaxy NGC 4388

Active galactic nuclei (AGN) may regulate galaxy evolution through radiatively driven winds and collimated jets, but their relative impact and coupling to the interstellar medium (ISM) remain uncertain. We investigate the ionized gas in the nearby ($D\sim$ 17 Mpc) Seyfert 2 galaxy NGC 4388, hosting a galaxy-scale ($\sim$1.6 kpc), low-power ($\sim1.4~\times~10^{42}~erg~s^{-1}$) bipolar radio jet projected roughly perpendicular to its edge-on disk. We analyze optical integral-field spectroscopic observations from the Wide Field Mode with adaptive optics of VLT/MUSE, complemented by VLA radio data tracing the jet. We map ionized-gas emission, kinematics, excitation, and dust attenuation. We reconstruct the de-projected 3D outflow geometry and velocity field using the MOKA3D kinematic model, and estimate its mass and energetics. The ionized gas shows a rotating disk and a kpc-scale biconical outflow. We measure a total ionized outflow mass of $\sim10^6~M_\odot$, a mass outflow rate of $\sim0.2~M_\odot$~yr$^{-1}$, and a kinetic power of $\sim3\times10^{40}~erg~s^{-1}$, which gives a coupling efficiency of $\sim1\%$ relative to both the jet kinetic and the radiation-driven nuclear wind power, indicating that either mechanism could drive the outflow. We detect an extended ($\sim$2 kpc) enhancement of the gas velocity dispersion along the galaxy disk plane, oriented perpendicular to the outflow and jet axes. These regions show optical line ratios consistent with shock excitation. The spatial correspondence with ALMA CO(2-1) emission is marginal, while enhanced stellar velocity dispersion prevents an exclusive jet interpretation. We report the first observational evidence that even a low-power radio jet oriented nearly perpendicular to the galaxy disk can efficiently couple with the ISM, suggesting that jet-induced perturbations are an important AGN feedback channel regardless of jet orientation.

astro-ph.GA↗

The complex effect of gas cooling and turbulence on AGN-driven outflow properties

(abridged) Accretion onto supermassive black holes (SMBHs) at close to the Eddington rate can influence the host galaxy via powerful winds. Theoretical models of such winds can explain observational correlations between SMBHs and their host galaxies and the powerful multi-phase outflows observed in a number of active galaxies. Analytic models usually assume spherical symmetry and a smooth gas distribution with an adiabatic equation of state. However, the interstellar medium in real galaxies is clumpy and cooling is important, complicating the analysis. We used a suite of idealised hydrodynamical simulations to isolate the effects of turbulence and cooling on the development and global properties of AGN wind-driven outflows on kiloparsec scales. We measured the outflow velocity, mass outflow rate and momentum and energy loading factors as the system evolved over 1.2 Myr and estimated plausible observationally derived values. We find that adiabatic simulations approximately reproduce the analytical estimates of outflow properties independently of turbulence or clumpiness. However, cooling reduces the outflow energy rate by 1-2 orders of magnitude in the smooth simulations and by up to one order of magnitude in the turbulent ones. The interplay between cooling and turbulence depends on AGN luminosity: in Eddington-limited AGN, turbulence enhances the coupling between the AGN wind and the gas, while the opposite happens in lower-luminosity simulations. This occurs because dense gas clumps are resilient to low-luminosity AGN feedback but get driven away by high-luminosity AGN feedback. The overall properties of multi-phase outflowing gas in our simulations qualitatively agree with observations of multi-phase outflows. We also find that using `observable' outflow properties leads to their parameters being underestimated by a factor of a few compared with real values.

astro-ph.GA↗

Feeding of active galactic nuclei by dynamical perturbations

There possibly was an AGN episode in the Galactic Centre about 6 Myr ago, powerful enough to produce the Fermi bubbles. We present numerical simulations of a possible scenario giving rise to an activity episode: a collision between a central gas ring surrounding the supermassive black hole (SMBH) and an infalling molecular cloud. We investigate different initial collision angles between the cloud and the ring. We follow the hydrodynamical evolution of the system following the collision using Gadget-3 hybrid N-body/SPH code and calculate the feeding rate of the SMBH accretion disc. This rate is then used as an input for a 1D thin $α$-disc model in order to calculate the AGN luminosity. By varying the disc feeding radii we determine the limiting values for possible AGN accretion disc luminosity. Small angle collisions do not result in significant mass transport to the centre of the system, while models with highest collision angles transport close to $40\%$ of the initial matter to the accretion disc. Even with ring and cloud masses equal to $10^4 \, M_\odot$, which is the lower limit of present-day mass of the Circumnuclear ring in the Galactic Centre, the energy released over an interval of 1.5 Myr can produce $\sim 10\%$ of that required to inflate the Fermi bubbles. If the gas ring in the Galactic Centre 6 Myr ago had a mass of at least $10^5 \, M_\odot$, our proposed scenario can explain the formation of the Fermi bubbles. We estimate that such high-impact collisions might occur once every $\sim 10^8$ yr in our Galaxy.

astro-ph.GA↗