A unified pseudo-Cℓ framework

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2019)

Authors:

David Alonso, Javier Sanchez, Anže Slosar

Black hole evolution: II. Spinning black holes in a supernova-driven turbulent interstellar medium

Monthly Notices of the Royal Astronomical Society Oxford University Press 440:3 (2014) 2333-2346

Authors:

Y Dubois, M Volonteri, J Silk, Julien Devriendt, Adrianne Slyz

Abstract:

Supermassive black holes (BH) accrete gas from their surroundings and coalesce with companions during galaxy mergers, and both processes change the BH mass and spin. By means of high-resolution hydrodynamical simulations of galaxies, either idealised or embedded within the cosmic web, we explore the effects of interstellar gas dynamics and external perturbations on BH spin evolution. All these physical quantities were evolved on-the-fly in a self-consistent manner. We use a 'maximal' model to describe the turbulence induced by stellar feedback to highlight its impact on the angular momentum of the gas accreted by the BH. Periods of intense star formation are followed by phases where stellar feedback drives large-scale outflows and hot bubbles. We find that BH accretion is synchronised with star formation, as only when gas is cold and dense do both processes take place. During such periods, gas motion is dominated by consistent rotation. On the other hand, when stellar feedback becomes substantial, turbulent motion randomises gas angular momentum. However BH accretion is strongly suppressed in that case, as cold and dense gas is lacking. In our cosmological simulation, at very early times (z>6), the galactic disc has not yet settled and no preferred direction exists for the angular momentum of the accreted gas, so the BH spin remains low. As the gas settles into a disc (6>z>3), the BH spin then rapidly reaches its maximal value. At lower redshifts (z<3), even when galaxy mergers flip the direction of the angular momentum of the accreted gas, causing it to counter-rotate, the BH spin magnitude only decreases modestly and temporarily. Should this be a typical evolution scenario for BH, it potentially has dramatic consequences regarding their origin and assembly, as accretion on maximally spinning BH embedded in thin Shakura-Sunyaev disc is significantly reduced.

Black hole evolution: II. Spinning black holes in a supernova-driven turbulent interstellar medium

Monthly Notices of the Royal Astronomical Society Oxford University Press 440:3 (2014) 2333-2346

Authors:

Y Dubois, M Volonteri, J Silk, Julien Devriendt, Adrianne Slyz

Abstract:

Supermassive black holes (BH) accrete gas from their surroundings and coalesce with companions during galaxy mergers, and both processes change the BH mass and spin. By means of high-resolution hydrodynamical simulations of galaxies, either idealised or embedded within the cosmic web, we explore the effects of interstellar gas dynamics and external perturbations on BH spin evolution. All these physical quantities were evolved on-the-fly in a self-consistent manner. We use a 'maximal' model to describe the turbulence induced by stellar feedback to highlight its impact on the angular momentum of the gas accreted by the BH. Periods of intense star formation are followed by phases where stellar feedback drives large-scale outflows and hot bubbles. We find that BH accretion is synchronised with star formation, as only when gas is cold and dense do both processes take place. During such periods, gas motion is dominated by consistent rotation. On the other hand, when stellar feedback becomes substantial, turbulent motion randomises gas angular momentum. However BH accretion is strongly suppressed in that case, as cold and dense gas is lacking. In our cosmological simulation, at very early times (z>6), the galactic disc has not yet settled and no preferred direction exists for the angular momentum of the accreted gas, so the BH spin remains low. As the gas settles into a disc (6>z>3), the BH spin then rapidly reaches its maximal value. At lower redshifts (z<3), even when galaxy mergers flip the direction of the angular momentum of the accreted gas, causing it to counter-rotate, the BH spin magnitude only decreases modestly and temporarily. Should this be a typical evolution scenario for BH, it potentially has dramatic consequences regarding their origin and assembly, as accretion on maximally spinning BH embedded in thin Shakura-Sunyaev disc is significantly reduced.

Cosmic shear with small scales: DES-Y3, KiDS-1000 and HSC-DR1

ArXiv 2403.13794 (2024)

Authors:

Carlos García-García, Matteo Zennaro, Giovanni Aricò, David Alonso, Raul E Angulo

EDGE – Dark matter or astrophysics? Breaking dark matter heating degeneracies with H i rotation in faint dwarf galaxies

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2024)

Authors:

Martin P Rey, Matthew DA Orkney, Justin I Read, Payel Das, Oscar Agertz, Andrew Pontzen, Anastasia A Ponomareva, Stacy Y Kim, William McClymont

Abstract:

Abstract Low-mass dwarf galaxies are expected to reside within dark matter halos that have a pristine, ‘cuspy’ density profile within their stellar half-light radii. This is because they form too few stars to significantly drive dark matter heating through supernova-driven outflows. Here, we study such simulated faint systems (104 ≤ M⋆ ≤ 2 × 106 M⊙) drawn from high-resolution (3 pc) cosmological simulations from the ‘Engineering Dwarf Galaxies at the Edge of galaxy formation’ (EDGE) project. We confirm that these objects have steep and rising inner dark matter density profiles at z = 0, little affected by galaxy formation effects. But five dwarf galaxies from the suite also showcase a detectable H i reservoir ($M_{\mathrm{H\, \small {I} }}\approx 10^{5}-10^{6} \, \mbox{M}_\mathrm{\odot }$), analogous to the observed population of faint, H i-bearing dwarf galaxies. These reservoirs exhibit episodes of ordered rotation, opening windows for rotation curve analysis. Within actively star-forming dwarfs, stellar feedback easily disrupts the tenuous H i discs (vφ, g ≈ 10 km s−1), making rotation short-lived (≪150 Myr) and more challenging to interpret for dark matter inferences. In contrast, we highlight a long-lived (≥500 Myr) and easy-to-interpret H i rotation curve extending to ≈2 r1/2, 3D in a quiescent dwarf, that has not formed new stars since z = 4. This stable gas disc is supported by an oblate dark matter halo shape that drives high angular momentum gas flows. Our results strongly motivate further searches for H i in rotation curves in the observed population of H i-bearing low-mass dwarfs, that provide a key regime to disentangle the respective roles of dark matter microphysics and galaxy formation effects in driving dark matter heating.