Black holes are believed to be one of the key ingredients of galaxy formation models, but it has been notoriously challenging to simulate them due to the very complex physics and large dynamical range of spatial scales involved. Here we address a significant shortcoming of a Bondi-Hoyle-like prescription commonly invoked to estimate black hole accretion in cosmological hydrodynamic simulations of galaxy formation, namely that the Bondi-Hoyle radius is frequently unresolved. We describe and implement a novel super-Lagrangian refinement scheme to increase, adaptively and 'on the fly', the mass and spatial resolution in targeted regions around the accreting black holes at limited computational cost. While our refinement scheme is generically applicable and flexible, for the purpose of this paper we select the smallest resolvable scales to match black holes' instantaneous Bondi radii, thus effectively resolving Bondi-Hoyle-like accretion in full galaxy formation simulations. This permits us to not only estimate gas properties close to the Bondi radius much more accurately, but also allows us to improve black hole accretion and feedback implementations. We thus devise a more generic feedback model where accretion and feedback depend on the geometry of the local gas distribution and where mass, energy and momentum loading are followed simultaneously. We present a series of tests of our refinement and feedback methods and apply them to models of isolated disc galaxies. Our simulations demonstrate that resolving gas properties in the vicinity of black holes is necessary to follow black hole accretion and feedback with a higher level of realism and that doing so allows us to incorporate important physical processes so far neglected in cosmological simulations.
Cosmological simulations almost invariably estimate the accretion of gas on to supermassive black holes using a Bondi-Hoyle-like prescription. Doing so ignores the effects of the angular momentum of the gas, which may prevent or significantly delay accreting material falling directly on to the black hole. We outline a black hole accretion rate prescription using a modified Bondi-Hoyle formulation that takes into account the angular momentum of the surrounding gas. Meaningful implementation of this modified Bondi-Hoyle formulation is only possible when the inner vorticity distribution is well r…
We present $\it{Hubble}$ $\it{Space}$ $\it{Telescope}$ proper motions in the direction of the star cluster NGC$\,$419 in the Small Magellanic Cloud. Because of the high precision of our measurements, for the first time it is possible to resolve the complex kinematics of the stellar populations located in the field, even along the tangential direction. In fact, the proper motions we measured allow us to separate cluster stars, which move on average with ($μ_α\cosδ^{\rm NGC\,419}, μ_δ^{\rm NGC\,419}$) = ($+0.878\pm0.055$, $-1.246\pm0.048$) mas yr$^{-1}$, from those of the Small Magellanic Cloud …
We studied the accretion disc structure in the doubly imaged lensed quasar SDSS J1339+1310 using $r$-band light curves and UV-visible to near-IR (NIR) spectra from the first 11 observational seasons after its discovery. The 2009$-$2019 light curves displayed pronounced microlensing variations on different timescales, and this microlensing signal permitted us to constrain the half-light radius of the 1930 Å continuum-emitting region. Assuming an accretion disc with an axis inclined at 60 deg to the line of sight, we obtained log$_{10}$($r_{1/2}$/cm) = 15.4$^{+0.3}_{-0.4}$. We also estimated the…
Born in rapidly evolving mini-halos during the first billion years of the Universe, super- massive black holes (SMBH) feed from gas flows spanning many orders of magnitude, from the cosmic web in which they are embedded to their event horizon. As such, accretion onto SMBHs constitutes a formidable challenge to tackle numerically, and currently requires the use of sub-grid models to handle the flow on small, unresolved scales. In this paper, we study the impact of resolution on the accretion pattern of SMBHs initially inserted at the heart of dense galactic gas clouds, using a custom super-Lagr…
We present here a self-consistent cosmological zoom-in simulation of a triple supermassive black hole (SMBH) system forming in a complex multiple galaxy merger. The simulation is run with an updated version of our code KETJU, which is able to follow the motion of SMBHs down to separations of tens of Schwarzschild radii while simultaneously modeling the large-scale astrophysical processes in the surrounding galaxies, such as gas cooling, star formation, and stellar and AGN feedback. Our simulation produces initially a SMBH binary system for which the hardening process is interrupted by the late…
As part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM), we present a measurement of the mass of the supermassive black hole (SMBH) in the nearby early-type galaxy NGC 0383 (radio source 3C 031). This measurement is based on Atacama Large Millimeter/sub-milimeter Array (ALMA) cycle 4 and 5 observations of the 12CO(2-1) emission line with a spatial resolution of 58x32pc2 (0."18x0."1). This resolution, combined with a channel width of 10 km/s, allows us to well resolve the radius of the black hole sphere of influence (measured as R_SOI = 316pc = 0."98), where we detect a cle…
We present new high-angular resolution observations toward the driving source of the HH 80-81 jet (IRAS 18162-2048). Continuum emission was observed with the Very Large Array at 7 mm and 1.3 cm, and with the Submillimeter Array at 860 microns, with angular resolutions of ~0"1 and ~0"8 respectively. Submillimeter observations of the sulfur oxide (SO) molecule are reported as well. At 1.3 cm the emission traces the well-known radio jet, while at 7 mm the continuum morphology is quadrupolar and seems to be produced by a combination of free-free and dust emission. An elongated structure perpendicu…
Resolving the black hole sphere of influence in a hyper-luminous obscured quasar at redshift 4.6
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Chinese Academy of Sciences South America Center for Astronomy（中国科学院南美天文学中心）；Instituto de Estudios Astrofísicos Facultad de Ingeniería y Ciencias, Universidad Diego Portales（迭戈·波特莱斯大学工程与科学学院天体物理研究所）；Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学天文与前沿科学研究院）；University of Chinese Academy of Sciences（中国科学院大学）；Department of Physics, University of Crete（克里特大学物理系）；Institute of Astrophysics, Foundation for Research and Technology-Hellas (FORTH)（希腊研究与技术基金会天体物理研究所）；Physics & Astronomy, University of Leicester（莱斯特大学物理与天文学系）；School of Sciences, European University Cyprus（塞浦路斯欧洲大学理学院）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）
Microlensing events provide a unique capacity to study the stellar remnant population of the Galaxy. Optical microlensing suffers from a near complete degeneracy between the mass, the velocity and the distance. However, a subpopulation of lensed stars, Mira variable stars, are also radio bright, exhibiting strong SiO masers. These are sufficiently bright and compact to permit direct imaging using existing very long baseline interferometers such as the Very Long Baseline Array (VLBA). We show that these events are relatively common, occurring at a rate of $\approx 2~{\rm yr^{\ -1}}$ of which $0…
Gas undergoing Bondi accretion onto a supermassive black hole (SMBH) becomes hotter toward smaller radii. We searched for this signature with a Chandra observation of the hot gas in NGC 3115, which optical observations show has a very massive SMBH. Our analysis suggests that we are resolving, for the first time, the accretion flow within the Bondi radius of an SMBH. We show that the temperature is rising toward the galaxy center as expected in all accretion models in which the black hole is gravitationally capturing the ambient gas. There is no hard central point source that could cause such a…
With the Submillimeter Array, the brightest (sub)millimeter continuum source in the OMC-2/3 region, MMS 6, has been observed in the 850 um continuum emission with approximately 10 times better angular resolution than previous studies (~0.3"; ~120 AU at Orion). The deconvolved size, the mass, and the column density of MMS 6-main are estimated to be 0.32"x0.29" (132 AUx120 AU), 0.29 Mo, and 2.1x10^{25} cm^{-2}, respectively. The estimated extremely high mean number density, 1.5x10^{10} cm^{-3}, suggests that MMS 6-main is likely optically thick at 850 um. We compare our observational data with t…
Direct measurements of the masses of supermassive black holes (SMBHs) are key to understanding their growth and constrain their symbiotic relationship to their host galaxies. However, current methods used to directly measure black hole masses in active quasars become challenging or impossible beyond $z\gtrsim0.2$. Spectroastrometry (SA) measures the spatial centroid of an object's spectrum as a function of wavelength, delivering angular resolution far better than the point-spread function (PSF) for high signal-to-noise ratio observations. We observed the luminous quasar SDSS J212329.47--005052…
We present sub-arcsecond resolution ALMA imaging of the CO(3-2) emission in two $z\sim2.5$ heavily reddened quasars (HRQs) - ULASJ1234+0907 and ULASJ2315+0143 - and their companion galaxies. Dynamical modeling of the resolved velocity fields enables us to constrain the molecular gas morphologies and host galaxy masses. Combining the new data with extensive multi-wavelength observations, we are able to study the relative kinematics of different molecular emission lines, the molecular gas fractions and the locations of the quasars on the M$_{\rm{BH}}$-M$_{\rm{gal}}$ relation. Despite having simi…
Prospects of resolving and localising individual supermassive black hole binaries with pulsar timing arrays: the host ranking challenge
Washington State University（华盛顿州立大学）；Institute of Astrophysics, FORTH（FORTH天体物理研究所）；Vanderbilt University（范德堡大学）；Fisk University（菲斯克大学）；Space Telescope Science Institute（太空望远镜科学研究所）；Johns Hopkins University（约翰斯·霍普金斯大学）；Niels Bohr International Academy, Niels Bohr Institute（尼尔斯·玻尔国际学院，尼尔斯·玻尔研究所）
While many tensions between Local Group (LG) satellite galaxies and LCDM cosmology have been alleviated through recent cosmological simulations, the spatial distribution of satellites remains an important test of physical models and physical versus numerical disruption in simulations. Using the FIRE-2 cosmological zoom-in baryonic simulations, we examine the radial distributions of satellites with Mstar > 10^5 Msun around 8 isolated Milky Way- (MW) mass host galaxies and 4 hosts in LG-like pairs. We demonstrate that these simulations resolve the survival and physical destruction of satellites …
Here we present deep (16 mumJy), very high (40 mas) angular resolution 1.14 mm, polarimetric, Atacama Large Millimeter/submillimeter Array (ALMA) observations towards the massive protostar driving the HH 80-81 radio jet. The observations clearly resolve the disk oriented perpendicular to the radio jet, with a radius of ~0.171 arcsec (~291 au at 1.7 kpc distance). The continuum brightness temperature, the intensity profile, and the polarization properties clearly indicate that the disk is optically thick for a radius of R<170 au. The linear polarization of the dust emission is detected almost a…
I briefly review advances in the understanding and modeling of relativistic stellar dynamics around massive black holes (MBHs) in galactic nuclei, following the inclusion of coherent relaxation and of secular processes in a new formal analytic description of the dynamics.
Tidal disruption events with SPH-EXA: resolving the return of the stream
University of Zurich（苏黎世大学）；Università degli Studi di Milano（米兰大学）；Syracuse University（雪城大学）；University of Leeds（利兹大学）；Swiss National Supercomputing Centre（瑞士国家超级计算中心）
WR 112 is a dust-forming carbon-rich Wolf-Rayet (WC) binary with a dusty circumstellar nebula that exhibits a complex asymmetric morphology, which traces the orbital motion and dust formation in the colliding winds of the central binary. Unraveling the complicated circumstellar dust emission around WR 112 therefore provides an opportunity to understand the dust formation process in colliding-wind WC binaries. In this work, we present a multi-epoch analysis of the circumstellar dust around WR 112 using seven high spatial resolution (FWHM $\sim0.3-0.4''$) N-band ($λ\sim12$ $μ$m) imaging observat…
