The impact of mechanical AGN feedback on the formation of massive early-type galaxies

We employ cosmological hydrodynamical simulations to investigate the effects of AGN feedback on the formation of massive galaxies with present-day stellar masses of $M_{stel} = 8.8 \times 10^{10} - 6.0 \times 10^{11} M_{sun}$. Using smoothed particle hydrodynamics simulations with a pressure-entropy formulation that allows an improved treatment of contact discontinuities and fluid mixing, we run three sets of simulations of 20 halos with different AGN feedback models: (1) no feedback, (2) thermal feedback, and (3) mechanical and radiation feedback. We assume that seed black holes are present at early cosmic epochs at the centre of emerging dark matter halos and trace their mass growth via gas accretion and mergers with other black holes. Both feedback models successfully recover the observed M_BH - sigma relation and black hole-to-stellar mass ratio for simulated central early-type galaxies. The baryonic conversion efficiencies are reduced by a factor of two compared to models without any AGN feedback at all halo masses. However, massive galaxies simulated with thermal AGN feedback show a factor of ~10-100 higher X-ray luminosities than observed. The mechanical/radiation feedback model reproduces the observed correlation between X-ray luminosities and velocity dispersion, e.g. for galaxies with sigma = 200 km/s, the X-ray luminosity is reduced from $10^{42}$ erg/s to $10^{40}$ erg/s. It also efficiently suppresses late time star formation, reducing the specific star formation rate from $10^{-10.5}$ $yr^{-1}$ to $10^{-14}$ $yr^{-1}$ on average and resulting in quiescent galaxies since z=2, whereas the thermal feedback model shows higher late time in-situ star formation rates than observed.Comment: 13 pages, 11 figures, accepted for the publication in MNRA

Consequences of Mechanical and Radiative Feedback from Black Holes in Disc Galaxy Mergers

We study the effect of AGN mechanical and radiation feedback on the formation of bulge dominated galaxies via mergers of disc galaxies. The merging galaxies have mass-ratios of 1:1 to 6:1 and include pre-existing hot gaseous halos to properly account for the global impact of AGN feedback. Using smoothed particle hydrodynamics simulation code (GADGET-3) we compare three models with different AGN feedback models: (1) no black hole and no AGN feedback; (2) thermal AGN feedback; and (3) mechanical and radiative AGN feedback. The last model is motivated by observations of broad line quasars which show winds with initial velocities of $v_w \ge$ 10,000 km/s and also heating associated with the central AGN X-ray radiation. The primary changes in gas properties due to mechanical AGN feedback are lower thermal X-ray luminosity from the final galaxy - in better agreement with observations - and galactic outflows with higher velocity $\sim 1000$ km/s similar to recent direct observations of nearby merger remnants. The kinetic energy of the outflowing gas is a factor of $\sim$ 20 higher than in the thermal feedback case. All merger remnants with momentum-based AGN feedback with $v_w \sim 10,000$ km/s and $\epsilon_w=2 \times 10^{-3}$, independent of their progenitor mass-ratios, reproduce the observed relations between stellar velocity dispersion and black hole mass ($M_{\rm bh} - \sigma$) as well as X-ray luminosity ($L_X - \sigma$) with $10^{37.5}$ erg/s $\lesssim L_X (0.3-8~{\rm keV}) \lesssim 10^{39.2}$ erg/s for velocity dispersions in the range of 120 km/s $\lesssim \sigma \lesssim$ 190 km/s. In addition, the mechanical feedback produces a much greater AGN variability. We also show that gas is more rapidly and impulsively stripped from the galactic centres driving a moderate increase in galaxy size and decrease in central density with the mechanical AGN feedback model.Comment: 16 pages, 10 figures, resubmitted to MNRA

AGN feedback, quiescence and CGM metal enrichment in early-type galaxies

We present three-dimensional hydrodynamical simulations showing the effect of kinetic and radiative AGN feedback on a model galaxy representing a massive quiescent low-redshift early-type galaxy of $M_* = 8.41\times 10^{10} M_\odot$, harbouring a $M_\mathrm{BH} = 4\times 10^8 M_\odot$ black hole surrounded by a cooling gaseous halo. We show that, for a total baryon fraction of $\sim 20\%$ of the cosmological value, feedback from the AGN can keep the galaxy quiescent for about 4.35 Gyr and with properties consistent with black hole mass and X-ray luminosity scaling relations. However, this can only be achieved if the AGN feedback model includes both kinetic and radiative feedback modes. The simulation with only kinetic feedback fails to keep the model galaxy fully quiescent, while one with only radiative feedback leads to excessive black-hole growth. For higher baryon fractions (e.g. 50\% of the cosmological value), the X-ray luminosities exceed observed values by at least one order of magnitude, and rapid cooling results in a star-forming galaxy. The AGN plays a major role in keeping the circumgalactic gas at observed metallicities of $Z/Z_\odot \gtrsim 0.3$ within the central $\sim 30$ kpc by venting nuclear gas enriched with metals from residual star formation activity. As indicated by previous cosmological simulations, our results are consistent with a model for which the black hole mass and the total baryon fraction are set at higher redshifts $z > 1$ and the AGN alone can keep the model galaxy on observed scaling relations. Models without AGN feedback violate both the quiescence criterion as well as CGM metallicity constraints.Comment: 19 pages, 15 figures. Accepted for publication in MNRA

Momentum Driving: which physical processes dominate AGN feedback?

The deposition of mechanical feedback from a supermassive black hole (SMBH) in an active galactic nucleus (AGN) into the surrounding galaxy occurs via broad-line winds which must carry mass and radial momentum as well as energy. The effect can be summarized by the dimensionless parameter $\eta=dot{M_outflow}/dot{M_accretion}= (2 \epsilon_w c^2)/v_w^2$ where (\epslion_w \equiv dot{E}_w/(dot{M_accretion} c^2)) is the efficiency by which accreted matter is turned into wind energy in the disc surrounding the central SMBH. The outflowing mass and omentum are proportional to $\eta$, and many prior treatments have essentially assumed that $\eta=0$. We perform one- and two-dimensional simulations and find that the growth of the central SMBH is very sensitive to the inclusion of the mass and momentum driving but is insensitive to the assumed mechanical efficiency. For example in representative calculations, the omission of momentum and mass feedback leads to an hundred fold increase in the mass of the SMBH to over 10^{10} \Msun. When allowance is made for momentum driving, the final SMBH mass is much lower and the wind efficiencies which lead to the most observationally acceptable results are relatively low with $\epsilon_w \lesssim 10^{-4}$.Comment: 10 pages, 8 figures, resubmitted to ApJ, added reference

The Role of Black Hole Feedback on Size and Structural Evolution in Massive Galaxies

We use cosmological hydrodynamical simulations to investigate the role of feedback from accreting black holes on the evolution of sizes, compactness, stellar core density and specific star-formation of massive galaxies with stellar masses of $M_{star} > 10^{10.9} M_{\odot}$. We perform two sets of cosmological zoom-in simulations of 30 halos to z=0: (1) without black holes and Active Galactic Nucleus (AGN) feedback and (2) with AGN feedback arising from winds and X-ray radiation. We find that AGN feedback can alter the stellar density distribution, reduce the core density within the central 1 kpc by 0.3 dex from z=1, and enhance the size growth of massive galaxies. We also find that galaxies simulated with AGN feedback evolve along similar tracks to those characterized by observations in specific star formation versus compactness. We confirm that AGN feedback plays an important role in transforming galaxies from blue compact galaxies into red extended galaxies in two ways: (1) it effectively quenches the star formation, transforming blue compact galaxies into compact quiescent galaxies and (2) it also removes and prevents new accretion of cold gas, shutting down in-situ star formation and causing subsequent mergers to be gas-poor or mixed. Gas poor minor mergers then build up an extended stellar envelope. AGN feedback also puffs up the central region through the fast AGN driven winds as well as the slow expulsion of gas while the black hole is quiescent. Without AGN feedback, large amounts of gas accumulate in the central region, triggering star formation and leading to overly massive blue galaxies with dense stellar cores.Comment: 13 pages, 7 figures, Accepted for publication in Ap

Localization of Na + channel clusters in narrowed perinexi of gap junctions enhances cardiac impulse transmission via ephaptic coupling: a model study

ABSTRACT: It has been proposed that when gap junctional coupling is reduced in cardiac tissue, action potential propagation can be supported via ephaptic coupling, a mechanism mediated by negative electric potentials occurring in narrow intercellular clefts of intercalated discs (IDs). Recent studies showed that sodium (Na(+)) channels form clusters near gap junction plaques in nanodomains called perinexi, where the ID cleft is even narrower. To examine the electrophysiological relevance of Na(+) channel clusters being located in perinexi, we developed a 3D finite element model of two longitudinally abutting cardiomyocytes, with a central Na(+) channel cluster on the ID membranes. When this cluster was located in the perinexus of a closely positioned gap junction plaque, varying perinexal width greatly modulated impulse transmission from one cell to the other, with narrow perinexi potentiating ephaptic coupling. This modulation occurred via the interplay of Na(+) currents, extracellular potentials in the cleft and patterns of current flow within the cleft. In contrast, when the Na(+) channel cluster was located remotely from the gap junction plaque, this modulation by perinexus width largely disappeared. Interestingly, the Na(+) current in the ID membrane of the pre‐junctional cell switched from inward to outward during excitation, thus contributing ions to the activating channels on the post‐junctional ID membrane. In conclusion, these results indicate that the localization of Na(+) channel clusters in the perinexi of gap junction plaques is crucial for ephaptic coupling, which is furthermore greatly modulated by perinexal width. These findings are relevant for a comprehensive understanding of cardiac excitation. KEY POINTS: Ephaptic coupling is a cardiac conduction mechanism involving nanoscale‐level interactions between the sodium (Na(+)) current and the extracellular potential in narrow intercalated disc clefts. When gap junctional coupling is reduced, ephaptic coupling acts in conjunction with the classical cardiac conduction mechanism based on gap junctional current flow. In intercalated discs, Na(+) channels form clusters that are preferentially located in the periphery of gap junction plaques, in nanodomains known as perinexi, but the electrophysiological role of these perinexi has never been examined. In our new 3D finite element model of two cardiac cells abutting each other with their intercalated discs, a Na(+) channel cluster located inside a narrowed perinexus facilitated impulse transmission via ephaptic coupling. Our simulations demonstrate the role of narrowed perinexi as privileged sites for ephaptic coupling in pathological situations when gap junctional coupling is decreased

Tortuous Cardiac Intercalated Discs Modulate Ephaptic Coupling

Cardiac ephaptic coupling, a mechanism mediated by negative electric potentials occurring in the narrow intercellular clefts of intercalated discs, can influence action potential propagation by modulating the sodium current. Intercalated discs are highly tortuous due to the mingling of plicate and interplicate regions. To investigate the effect of their convoluted structure on ephaptic coupling, we refined our previous model of an intercalated disc and tested predefined folded geometries, which we parametrized by orientation, amplitude and number of folds. Ephaptic interactions (assessed by the minimal cleft potential and amplitude of the sodium currents) were reinforced by concentric folds. With increasing amplitude and number of concentric folds, the cleft potential became more negative during the sodium current transient. This is explained by the larger resistance between the cleft and the bulk extracellular space. In contrast, radial folds attenuated ephaptic interactions and led to a less negative cleft potential due to a decreased net cleft resistance. In conclusion, despite limitations inherent to the simplified geometries and sodium channel distributions investigated as well as simplifications regarding ion concentration changes, these results indicate that the folding pattern of intercalated discs modulates ephaptic coupling

ANALISIS PENGENDALIAN PERSEDIAAN BAHAN BAKU PAPAN JATI TERHADAP KELANCARAN PRODUKSI PADA MEBEL PESONA JEPARA DI KOTA KUPANG

Penelitian ini bertujuan untuk mengetahui pengendalian persediaan bahan baku pada Mebel Pesona Jepara di kota kupang. Metode Analisis data yang digunakan adalah deskriptif kuantitatif, dengan menggunakan metode EOQ, persediaan pengaman (Safety Stock), titik pesan kembali (Reorder Point) dan peramalan persediaan bahan baku. Berdasarkan hasil penelitian menunjukan Economic Order Quantity tahun 2018 sebanyak 587 lembar dengan frekuensi 5 pemesanan kali dalam setahun, pada tahun 2019 sebanyak 621 lembar dengan frekuensi 6 kali pemesanan dalam setahun, pada tahun 2020 sebanyak 742 lembar dengan frekuensi 7 kali pemesanan dalam setahun. Menurut perhitungan Safety Stock tahun 2018 sebanyak 64 lembar, tahun 2019 sebanyak 88 lembar, tahun 2020 sebanyak 100 lembar, Reorder Point tahun 2018 sebanyak 128 lembar, tahun 2019 sebanyak 176 lembar, tahun 2020 sebanyak 200 lembar. Berdasarkan penelitian ini dapat disimpulkan bahwa metode  EOQ lebih efisien. Dan penelitian tersebut menyarankan informasi yang tepat tentang jumlah pengadaan bahan baku menggunakan EOQ, perusahaan perlu memantau keselamatan stock bahan baku dan menentukan waktu yang tepat untuk memesan bahan baku menggunakan metode Reorder Point terhadap kelancaran proses produksi. Kata Kunci : EOQ, Safety Stock, Reorder Poin

The Impact of Outflows driven by Active Galactic Nuclei on Metals in and around Galaxies

Metals in the hot gaseous halos of galaxies encode the history of star formation as well as the feedback processes that eject metals from the galaxies. X-ray observations suggest that massive galaxies have extended distributions of metals in their gas halos. We present predictions for the metal properties of massive galaxies and their gaseous halos from recent high resolution zoom-in simulations that include mechanical and radiation driven feedback from Active Galactic Nuclei (AGN). In these simulations, AGN launch high-velocity outflows, mimicking observed broad absorption line winds. By comparing two sets of simulations with and without AGN feedback, we show that our prescription for AGN feedback is capable of driving winds and enriching halo gas `inside-out' by spreading centrally enriched metals to the outskirts of galaxies, into the halo and beyond. The metal (iron) profiles of halos simulated with AGN feedback have a flatter slope than those without AGN feedback, consistent with recent X-ray observations. The predicted gas iron abundance of group scale galaxies simulated with AGN feedback is $Z_{\rm Fe} = 0.23$ $Z_{\rm Fe,\odot}$ at $0.5 r_{500}$, which is 2.5 times higher than that in simulations without AGN feedback. In these simulations, AGN winds are also important for the metal enrichment of the intergalactic medium, as the vast majority of metals ejected from the galaxy by AGN-driven winds end up beyond the halo virial radius.Comment: Accepted for publication in ApJ. 16 pages, 9 figures. Key figures are 8 &