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Showing 1-9 of about 9 results.
Dust entrainment in galactic windsKannan, RahulVogelsberger, M.Marinacci, F.Sales, L., V.Torrey, P.Hernquist, L.DOI: info:10.1093/mnras/stab416v. 503No. 1336–343
Kannan, Rahul, Vogelsberger, M., Marinacci, F., Sales, L., V., Torrey, P., and Hernquist, L. 2021. "Dust entrainment in galactic winds." Monthly Notices of the Royal Astronomical Society 503 (1):336– 343.
ID: 159530
Type: article
Authors: Kannan, Rahul; Vogelsberger, M.; Marinacci, F.; Sales, L., V.; Torrey, P.; Hernquist, L.
Abstract: Winds driven by stellar feedback are an essential part of the galactic ecosystem and are the main mechanism through which low-mass galaxies regulate their star formation. These winds are generally observed to be multiphase with detections of entrained neutral and molecular gas. They are also thought to enrich the circumgalactic medium around galaxies with metals and dust. This ejected dust encodes information about the integrated star formation and outflow history of the galaxy. Therefore it is important to understand how much dust is entrained and driven out of the disc by galactic winds. Here, we demonstrate that stellar feedback is efficient in driving dust-enriched winds and eject enough material to account for the amount of extraplanar dust observed in nearby galaxies. The amount of ejected dust depends on the sites from where they are launched, with dustier galaxies launching more dust-enriched outflows. Moreover, the outflowing cold and dense gas is significantly more dust enriched than the volume filling hot and tenuous material. These results provide an important new insight into the dynamics, structure, and composition of galactic winds and their role in determining the dust content of the extragalactic gas in galaxies.
Radiative AGN feedback on a moving mesh: the impact of the galactic disc and dust physics on outflow propertiesBarnes, David J.Kannan, RahulVogelsberger, MarkMarinacci, FedericoDOI: info:10.1093/mnras/staa591v. 4941143–1164
Barnes, David J., Kannan, Rahul, Vogelsberger, Mark, and Marinacci, Federico. 2020. "Radiative AGN feedback on a moving mesh: the impact of the galactic disc and dust physics on outflow properties." Monthly Notices of the Royal Astronomical Society 494:1143– 1164.
ID: 157317
Type: article
Authors: Barnes, David J.; Kannan, Rahul; Vogelsberger, Mark; Marinacci, Federico
Abstract: Feedback from accreting supermassive black holes (BHs), active galactic nuclei (AGNs), is now a cornerstone of galaxy formation models. In this work, we present radiation-hydrodynamic simulations of radiative AGN feedback using the novel arepo-rt code. A central BH emits radiation at a constant luminosity and drives an outflow via radiation pressure on dust grains. Utilizing an isolated Navarro-Frenk-White (NFW) halo we validate our set-up in the single- and multiscattering regimes, with the simulated shock front propagation in excellent agreement with the expected analytic result. For a spherically symmetric NFW halo, an examination of the simulated outflow properties with radiation collimation demonstrates a decreasing mass outflow rate and momentum flux, but increasing kinetic power and outflow velocity with decreasing opening angle. We then explore the impact of a central disc galaxy and the assumed dust model on the outflow properties. The contraction of the halo during the galaxy's formation and modelling the production of dust grains result in a factor 100 increase in the halo's optical depth. Radiation then couples momentum more efficiently to the gas, driving a stronger shock and producing a mass-loaded ∼103 M yr-1 outflow with a velocity of ∼2000 km s-1. However, the inclusion of dust destruction mechanisms, like thermal sputtering, leads to the rapid destruction of dust grains within the outflow, reducing its properties below the initial NFW halo. We conclude that radiative AGN feedback can drive outflows, but a thorough numerical and physical treatment is required to assess its true impact.
Efficacy of early stellar feedback in low gas surface density environmentsKannan, RahulMarinacci, FedericoSimpson, Christine M.Glover, Simon C. O.Hernquist, LarsDOI: info:10.1093/mnras/stz3078v. 4912088–2103
Kannan, Rahul, Marinacci, Federico, Simpson, Christine M., Glover, Simon C. O., and Hernquist, Lars. 2020. "Efficacy of early stellar feedback in low gas surface density environments." Monthly Notices of the Royal Astronomical Society 491:2088– 2103.
ID: 155675
Type: article
Authors: Kannan, Rahul; Marinacci, Federico; Simpson, Christine M.; Glover, Simon C. O.; Hernquist, Lars
Abstract: We present a suite of high-resolution radiation hydrodynamic simulations of a small patch (1 kpc2) of the interstellar medium (ISM) performed with AREPO-RT, with the aim to quantify the efficacy of various feedback processes like supernova (SN) explosions, photoheating, and radiation pressure in low gas surface density galaxies (Σgas ≃ 10 M pc-2). We show that radiative feedback decrease the star formation rate and therefore the total stellar mass formed by a factor of approximately two. This increases the gas depletion time-scale and brings the simulated Kennicutt-Schmidt relation closer to the observational estimates. Radiation feedback coupled with SN is more efficient at driving outflows with the mass and energy loading increasing by a factor of ∼10. This increase is mainly driven by the additional entrainment of medium- density (10-2 cm-3 ≤ n ≤ n -3) warm (300 K ≤ T < 8000 K) material. Therefore, including radiative feedback tends to launch colder, denser, and more mass- and energy- loaded outflows. This is because photoheating of the high-density gas around a newly formed star overpressurizes the region, causing it to expand. This reduces the ambient density in which the SN explode by a factor of 10-100 which in turn increases their momentum output by a factor of ∼1.5-2.5. Finally, we note that in these low gas surface density environments, radiative feedback primarily impact the ISM via photoheating and radiation pressure has only a minimal role in regulating star formation.
Enhancing AGN efficiency and cool-core formation with anisotropic thermal conductionBarnes, David J.Kannan, RahulVogelsberger, MarkPfrommer, ChristophPuchwein, EwaldWeinberger, RainerSpringel, VolkerPakmor, RüdigerNelson, DylanMarinacci, FedericoPillepich, AnnalisaTorrey, PaulHernquist, LarsDOI: info:10.1093/mnras/stz1814v. 4883003–3013
Barnes, David J., Kannan, Rahul, Vogelsberger, Mark, Pfrommer, Christoph, Puchwein, Ewald, Weinberger, Rainer, Springel, Volker, Pakmor, Rüdiger, Nelson, Dylan, Marinacci, Federico, Pillepich, Annalisa, Torrey, Paul, and Hernquist, Lars. 2019. "Enhancing AGN efficiency and cool-core formation with anisotropic thermal conduction." Monthly Notices of the Royal Astronomical Society 488:3003– 3013.
ID: 154419
Type: article
Authors: Barnes, David J.; Kannan, Rahul; Vogelsberger, Mark; Pfrommer, Christoph; Puchwein, Ewald; Weinberger, Rainer; Springel, Volker; Pakmor, Rüdiger; Nelson, Dylan; Marinacci, Federico; Pillepich, Annalisa; Torrey, Paul; Hernquist, Lars
Abstract: Understanding how baryonic processes shape the intracluster medium (ICM) is of critical importance to the next generation of galaxy cluster surveys. However, many models of structure formation neglect potentially important physical processes, like anisotropic thermal conduction (ATC). We explore the impact of ATC on the prevalence of cool-cores (CCs) via 12 pairs of magnetohydrodynamical galaxy cluster simulations, using the IllustrisTNG model with and without ATC. Examining their properties we find that the addition of ATC has a negligible impact on the median rotation measure, plasma β, the magnetic field-radial direction angle, and the effective Spitzer value. However, the scatter in the angle and effective Spitzer value is 50 per cent larger with ATC because the magnetic field aligns with the azimuthal direction to a greater extent in relaxed clusters. ATC's impact varies from cluster to cluster and with CC criterion, but its inclusion produces a systematic shift to larger CC fractions at z = 0 for all CC criteria considered. Additionally, the inclusion of ATC flattens the CC fraction redshift evolution, helping to ease the tension with the observed evolution. With ATC, the energy required for the central black hole to self-regulate is reduced by 24 per cent and the gas fraction at 0.01 r_{500} increases by 100 per cent, producing larger CC fractions. ATC makes the ICM unstable to perturbations and the increased efficiency of AGN feedback suggests that its inclusion results in a greater level of mixing in the ICM, demonstrated by the 10 per cent reduction in central metallicity for clusters with ATC.
AREPO-RT: radiation hydrodynamics on a moving meshKannan, RahulVogelsberger, MarkMarinacci, FedericoMcKinnon, RyanPakmor, RüdigerSpringel, VolkerDOI: info:10.1093/mnras/stz287v. 485117–149
Kannan, Rahul, Vogelsberger, Mark, Marinacci, Federico, McKinnon, Ryan, Pakmor, Rüdiger, and Springel, Volker. 2019. "AREPO-RT: radiation hydrodynamics on a moving mesh." Monthly Notices of the Royal Astronomical Society 485:117– 149.
ID: 155153
Type: article
Authors: Kannan, Rahul; Vogelsberger, Mark; Marinacci, Federico; McKinnon, Ryan; Pakmor, Rüdiger; Springel, Volker
Abstract: We introduce AREPO-RT, a novel radiation hydrodynamic (RHD) solver for the unstructured moving-mesh code AREPO. Our method solves the moment- based radiative transfer equations using the M1 closure relation. We achieve second-order convergence by using a slope-limited linear spatial extrapolation and a first-order time prediction step to obtain the values of the primitive variables on both sides of the cell interface. A Harten-Lax-van Leer flux function, suitably modified for moving meshes, is then used to solve the Riemann problem at the interface. The implementation is fully conservative and compatible with the individual time-stepping scheme of AREPO. It incorporates atomic hydrogen (H) and helium (He) thermochemistry, which is used to couple the ultraviolet radiation field to the gas. Additionally, infrared (IR) radiation is coupled to the gas under the assumption of local thermodynamic equilibrium between the gas and the dust. We successfully apply our code to a large number of test problems, including applications such as the expansion of H II regions, radiation pressure-driven outflows, and the levitation of optically thick layer of gas by trapped IR radiation. The new implementation is suitable for studying various important astrophysical phenomena, such as the effect of radiative feedback in driving galactic scale outflows, radiation-driven dusty winds in high-redshift quasars, or simulating the reionization history of the Universe in a self-consistent manner.
Local photoionization feedback effects on galaxiesObreja, AuraMacciò, Andrea V.Moster, BenjaminUdrescu, Silviu M.Buck, TobiasKannan, RahulDutton, Aaron A.Blank, MarvinDOI: info:10.1093/mnras/stz2639v. 4901518–1538
Obreja, Aura, Macciò, Andrea V., Moster, Benjamin, Udrescu, Silviu M., Buck, Tobias, Kannan, Rahul, Dutton, Aaron A., and Blank, Marvin. 2019. "Local photoionization feedback effects on galaxies." Monthly Notices of the Royal Astronomical Society 490:1518– 1538.
ID: 154528
Type: article
Authors: Obreja, Aura; Macciò, Andrea V.; Moster, Benjamin; Udrescu, Silviu M.; Buck, Tobias; Kannan, Rahul; Dutton, Aaron A.; Blank, Marvin
Abstract: We implement an optically thin approximation for the effects of the local radiation field from stars and hot gas on the gas heating and cooling in the N-body smoothed particle hydrodynamics code GASOLINE2. We resimulate three galaxies from the NIHAO project: one dwarf, one Milky Way-like, and one massive spiral, and study what are the local radiation field effects on various galaxy properties. We also study the effects of varying the ultraviolet background (UVB) model, by running the same galaxies with two different UVBs. Galaxy properties at z = 0 like stellar mass, stellar effective mass radius, H I mass, and radial extent of the H I disc show significant changes between the models with and without the local radiation field, and smaller differences between the two UVB models. The intrinsic effect of the local radiation field through cosmic time is to increase the equilibrium temperature at the interface between the galaxies and their circumgalactic media (CGM), moving this boundary inwards, while leaving relatively unchanged the gas inflow rate. Consequently, the temperature of the inflow increases when considering the local radiation sources. This temperature increase is a function of total galaxy mass, with a median CGM temperature difference of one order of magnitude for the massive spiral. The local radiation field suppresses the stellar mass growth by 20 per cent by z = 0 for all three galaxies, while the H I mass is roughly halved. The differences in the gas phase diagrams, significantly impact the H I column densities, shifting their peaks in the distributions towards lower NH I.
Dust in and around galaxies: dust in cluster environments and its impact on gas coolingVogelsberger, MarkMcKinnon, RyanO'Neil, StephanieMarinacci, FedericoTorrey, PaulKannan, RahulDOI: info:10.1093/mnras/stz1644v. 4874870–4883
Vogelsberger, Mark, McKinnon, Ryan, O'Neil, Stephanie, Marinacci, Federico, Torrey, Paul, and Kannan, Rahul. 2019. "Dust in and around galaxies: dust in cluster environments and its impact on gas cooling." Monthly Notices of the Royal Astronomical Society 487:4870– 4883.
ID: 154269
Type: article
Authors: Vogelsberger, Mark; McKinnon, Ryan; O'Neil, Stephanie; Marinacci, Federico; Torrey, Paul; Kannan, Rahul
Abstract: Simulating the dust content of galaxies and their surrounding gas is challenging due to the wide range of physical processes affecting the dust evolution. Here we present cosmological hydrodynamical simulations of a cluster of galaxies, M_200,crit=6 × 10^{14}{ M_\odot }, including a novel dust model for the moving mesh code AREPO. This model includes dust production, growth, supernova-shock-driven destruction, ion-collision-driven thermal sputtering, and high-temperature dust cooling through far-infrared reradiation of collisionally deposited electron energies. Adopting a rather low thermal sputtering rate, we find, consistent with observations, a present-day overall dust-to-gas ratio of ̃2 × 10-5, a total dust mass of {̃ } 2× 10^9{ M_\odot }, and a dust mass fraction of ̃3 × 10-6. The typical thermal sputtering time-scales within {̃ } 100 kpc are around {̃ } 10 Myr, and increase towards the outer parts of the cluster to {̃ } 10^3 Myr at a cluster-centric distance of 1 Mpc. The condensation of gas-phase metals into dust grains reduces high-temperature metal-line cooling, but also leads to additional dust infrared cooling. The additional infrared cooling changes the overall cooling rate in the outer parts of the cluster, beyond {̃ } 1 Mpc, by factors of a few. This results in noticeable changes of the entropy, temperature, and density profiles of cluster gas once dust formation is included. The emitted dust infrared emission due to dust cooling is consistent with observational constraints.
Simulating the effect of photoheating feedback during reionizationWu, XiaohanKannan, RahulMarinacci, FedericoVogelsberger, MarkHernquist, LarsDOI: info:10.1093/mnras/stz1726v. 488419–437
Wu, Xiaohan, Kannan, Rahul, Marinacci, Federico, Vogelsberger, Mark, and Hernquist, Lars. 2019. "Simulating the effect of photoheating feedback during reionization." Monthly Notices of the Royal Astronomical Society 488:419– 437.
ID: 154414
Type: article
Authors: Wu, Xiaohan; Kannan, Rahul; Marinacci, Federico; Vogelsberger, Mark; Hernquist, Lars
Abstract: We present self-consistent radiation hydrodynamic simulations of hydrogen reionization performed with AREPO-RT complemented by a state- of-the-art galaxy formation model. We examine how photoheating feedback, due to reionization, shapes the galaxies properties. Our fiducial model completes reionization by z ≈ 6 and matches observations of the Ly α forest, the cosmic microwave background electron scattering optical depth, the high-redshift ultraviolet (UV) luminosity function, and stellar mass function. Contrary to previous works, photoheating suppresses star formation rates by more than 50{{ per cent}} only in haloes less massive than ̃108.4 M (̃108.8 M) at z = 6 (z = 5), suggesting inefficient photoheating feedback from photons within galaxies. The use of a uniform UV background that heats up the gas at z ≈ 10.7 generates an earlier onset of suppression of star formation compared to our fiducial model. This discrepancy can be mitigated by adopting a UV background model with a more realistic reionization history. In the absence of stellar feedback, photoheating alone is only able to quench haloes less massive than ̃109 M at z ≳ 5, implying that photoheating feedback is sub-dominant in regulating star formation. In addition, stellar feedback, implemented as a non-local galactic wind scheme in the simulations, weakens the strength of photoheating feedback by reducing the amount of stellar sources. Most importantly, photoheating does not leave observable imprints in the UV luminosity function, stellar mass function, or the cosmic star formation rate density. The feasibility of using these observables to detect imprints of reionization therefore requires further investigation.
Imprints of temperature fluctuations on the z ̃ 5 Lyman-α forest: a view from radiation-hydrodynamic simulations of reionizationWu, XiaohanMcQuinn, MatthewKannan, RahulD'Aloisio, AnsonBird, SimeonMarinacci, FedericoDavé, RomeelHernquist, LarsDOI: info:10.1093/mnras/stz2807v. 4903177–3195
Wu, Xiaohan, McQuinn, Matthew, Kannan, Rahul, D'Aloisio, Anson, Bird, Simeon, Marinacci, Federico, Davé, Romeel, and Hernquist, Lars. 2019. "Imprints of temperature fluctuations on the z ̃ 5 Lyman-α forest: a view from radiation-hydrodynamic simulations of reionization." Monthly Notices of the Royal Astronomical Society 490:3177– 3195.
ID: 154530
Type: article
Authors: Wu, Xiaohan; McQuinn, Matthew; Kannan, Rahul; D'Aloisio, Anson; Bird, Simeon; Marinacci, Federico; Davé, Romeel; Hernquist, Lars
Abstract: Reionization leads to large spatial fluctuations in the intergalactic temperature that can persist well after its completion. We study the imprints of such fluctuations on the z ̃ 5 Ly α forest flux power spectrum using a set of radiation-hydrodynamic simulations that model different reionization scenarios. We find that large-scale coherent temperature fluctuations bring {̃}20-60{{ per cent}} extra power at k ̃ 0.002 s km-1, with the largest enhancements in the models where reionization is extended or ends the latest. On smaller scales (k ≳ 0.1 s km-1), we find that temperature fluctuations suppress power by {≲}10{{ per cent}}. We find that the shape of the power spectrum is mostly sensitive to the reionization mid-point rather than temperature fluctuations from reionization's patchiness. However, for all of our models with reionization mid-points of z ≤ 8 (z ≤ 12), the shape differences are {≲}20{{ per cent}} ({≲}40{{ per cent}}) because of a surprisingly well-matched cancellation between thermal broadening and pressure smoothing that occurs for realistic thermal histories. We also consider fluctuations in the ultraviolet background, finding their impact on the power spectrum to be much smaller than temperature fluctuations at k ≳ 0.01 s km-1. Furthermore, we compare our models to power spectrum measurements, finding that none of our models with reionization mid-points of z < 8 is strongly preferred over another and that all of our models with mid-points of z ≥ 8 are excluded at 2.5σ. Future measurements may be able to distinguish between viable reionization models if they can be performed at lower k or, alternatively, if the error bars on the high-k power can be reduced by a factor of 1.5.