We use a semi-analytic galaxy formation model to study the co-evolution of supermassive black holes (SMBHs) with their host galaxies. Although the coalescence of SMBHs is not important, the quasar-mode accretion induced by mergers plays a dominant role in the growth of SMBHs. Mergers play a more important role in the growth of SMBH host galaxies than in the SMBH growth. It is the combined contribution from quasar mode accretion and mergers to the SMBH growth and the combined contribution from starburst and mergers to their host galaxy growth that determine the observed scaling relation between the SMBH masses and their host galaxy masses. We also find that mergers are more important in the growth of SMBH host galaxies compared to normal galaxies which share the same stellar mass range as the SMBH host galaxies.
We present an analysis of the instantaneous supermassive black hole (SMBH) accretion rates in a collection of 1563 post-merger galaxies drawn from the IllustrisTNG simulation. Our sample consists of galaxies that have experienced a merger in the last simulation snapshot (within ~160 Myrs of coalescence) in the redshift range 0<z<1, with merger stellar mass ratios >1:10 and post-merger stellar masses > $10^{10} M_{\odot}$. We find that, on average, the accretion rates of the post-mergers are ~1.7 times higher than in a control sample and that post-mergers are 3-4 times more likely to experience…
In this paper we quantify the gas accretion rate from minor mergers onto star-forming galaxies in the Local Universe using HI observations of 148 nearby spiral galaxies (WHISP sample). We developed a dedicated code that iteratively analyses HI data-cubes, finds dwarf gas-rich satellites around larger galaxies and estimates an upper limit to the gas accretion rate. We found that 22% of the galaxies have at least one detected dwarf companion. We made the very stringent assumption that all satellites are going to merge in the shortest possible time transferring all their gas to the main galaxies.…
We studied the final phases of galactic mergers, focusing on interactions between supermassive black holes (SMBHs) and the interstellar medium in a central sub-kpc region, using an N-body/hydrodynamics code. This numerical experiment aims to understand the fate of the gas supplied by mergers of two or more galaxies with SMBHs, whose masses are $10^7 M_\odot$. We observed that the mass accretion rate to one SMBH exceeds the Eddington accretion rate when the distance between two black holes (BHs) rapidly decreases. However, this rapid accretion phase does not last for more than $10^7$ yrs, and i…
We introduce a new model for the accretion and feedback of supermassive black hole (SMBH) binaries to the KETJU code, which enables us to resolve the evolution of SMBH binaries down to separations of tens of Schwarzschild radii in gas-rich galaxy mergers. Our subgrid binary accretion model extends the widely used Bondi--Hoyle--Lyttleton accretion into the binary phase and incorporates preferential mass accretion onto the secondary SMBH, which is motivated by results from small-scale hydrodynamical circumbinary disc simulations. We perform idealised gas-rich disc galaxy merger simulations using…
We study the statistical properties of mergers between central and satellite galaxies in galaxy clusters in the redshift range $0<z<1$, using a sample of dark-matter only cosmological N-body simulations from Le SBARBINE dataset. Using a spherical overdensity algorithm to identify dark-matter haloes, we construct halo merger trees for different values of the over-density $Δ_c$. While the virial overdensity definition allows us to probe the accretion of satellites at the cluster virial radius $r_{vir}$, higher overdensities probe satellite mergers in the central region of the cluster, down to $\…
Using a new, high-resolution cosmological hydrodynamic simulation of a Milky Way-type (MW-type) galaxy, we explore how a merger-rich assembly history affects the mass budget of the central supermassive black hole (SMBH). We examine a MW-mass halo at the present epoch whose evolution is characterized by several major mergers to isolate the importance of merger history on black hole accretion. This study is an extension of Bellovary et. al. 2013, which analyzed the accretion of high mass, high redshift galaxies and their central black holes, and found that the gas content of the central black ho…
We measure the role of major and minor mergers in forming the stellar masses of galaxies over $0<z<3$ using a combination of $\sim 3.25$ deg$^{2}$ of the deepest ground based near-infrared imaging taken to date as part of the REFINE survey. We measure the pair fraction and merger fractions for galaxy mergers of different mass ratios, and quantify the merger rate with newly measured time-scales derived from the Illustris simulation as a function of redshift and merger mass ratio. We find that over $0 < z < 3$ major mergers with mass ratios greater than 1:4 occur $0.85^{+0.19}_{-0.20}$ times on …
We study stellar and black hole mass assembly in a sample of 42 infrared-luminous galaxy mergers at z<0.3 by combining results from radiative transfer modelling with archival measures of molecular gas and black hole mass. The ratios of stellar mass, molecular gas mass, and black hole mass to each other are consistent with those of massive gas-rich galaxies at z<0.3. The advanced mergers may show increased black hole mass to stellar mass ratios, consistent with the transition from AGN to ellipticals and implying substantial black hole mass growth over the course of the merger. Star formation ra…
Representing simultaneous black hole accretion during a merger, binary active galactic nuclei (AGNs) could provide valuable observational constraints to models of galaxy mergers and AGN triggering. High-resolution radio interferometer imaging offers a promising method to identify a large and uniform sample of binary AGNs, because it probes a generic feature of nuclear activity and is free from dust obscuration. Our previous search yielded 52 strong candidates of kpc-scale binaries over the 92 deg$^2$ of the Sloan Digital Sky Survey (SDSS) Stripe 82 area with 2"-resolution Very Large Array (VLA…
A key unresolved question is the role that galaxy mergers play in driving stellar mass growth over cosmic time. Recent observational work hints at the possibility that the overall contribution of `major' mergers (mass ratios $\gtrsim$1:4) to cosmic stellar mass growth may be small, because they enhance star formation rates by relatively small amounts at high redshift, when much of today's stellar mass was assembled. However, the heterogeneity and relatively small size of today's datasets, coupled with the difficulty in identifying genuine mergers, makes it challenging to $\textit{empirically}$…
The majority of gravitational wave (GW) events detected so far by LIGO/Virgo originate from binary black hole (BBH) mergers. Among the different binary evolution paths, the merger of BBHs in accretion discs of active galactic nuclei (AGNs) is a possible source of GW detections. We consider an idealised analytical model of the orbital evolution of BBHs embedded in an AGN accretion disc. In this framework, the disc-binary interaction increases the orbital eccentricity and decreases the orbital separation, driving the BBH into a regime where GW emission eventually leads to coalescence. We compute…
The accretion history of the Milky Way V. The kinematics of most globular clusters trace the merger epochs
Observatoire de Paris, Université PSL, CNRS（巴黎天文台，巴黎文理研究大学，法国国家科学研究中心）；Center for Astronomy, Space Science and Astrophysics, Independent University, Bangladesh（孟加拉独立大学天体物理、空间科学与天文学中心）
We study the infall of a subhalo in its parent halo due to dynamical friction. Using expected mass and spatial distributions of subhaloes, in unison with the derived infall time-scale, we calculate the expected merger stellar mass growth rate (SMGR) of the central galaxy in two different models (instantaneous and continuous merging). We find that our continuous merging SMGR (which corresponds to smooth accretion from satellites) agrees with the results of the Millennium-II simulation, predicting low growth rates for low stellar masses ($10^{8}$ M$_{\odot}-10^{10}$ M$_{\odot}$) and accelerating…
The Disk of Satellites (DoS) observed in the Andromeda galaxy is a thin and extended group of satellites, nearly perpendicular to the disk plane, that share a common direction of rotation about the centre of Andromeda. Although a DoS is also observed in the Milky Way galaxy, the prevalance of such structures in more distant galaxies remains controversial. Explanations for the formation of such DoSs vary widely from filamentary infall, or flattening due to the potential field from large scale structure, to galaxy interactions in a Mondian paradigm. Here we present an alternative scenario -- dur…
Hierarchical models of galaxy formation predict that galaxy mergers represent a significant transitional stage of rapid supermassive black hole (SMBH) growth. Yet, the connection between the merging process and enhanced active galactic nuclei (AGN) activity as well as the timescale of SMBH mergers remains highly uncertain. The breakthrough in reconciling the importance of galaxy mergers with black hole growth lies in a thoroughly-studied census of dual AGN across cosmic history, which will be enabled by next-generation observational capabilities, theoretical advances, and simulations. This whi…
We study of the role of major mergers (mass ratios >1:4) in driving size growth in high-redshift (1<z<2) spheroidal galaxies (SGs) with stellar masses between 10^9.5 MSun and 10^10.7 MSun. This is a largely unexplored mass range at this epoch, containing the progenitors of more massive SGs on which the bulk of the size-evolution literature is based. We visually split our SGs into systems that are relaxed and those that exhibit tidal features indicative of a recent merger. Numerical simulations indicate that, given the depth of our images, only tidal features due to major mergers will be detect…
Building galaxy merger trees from a state-of-the-art cosmological hydrodynamics simulation, Horizon-AGN, we perform a statistical study of how mergers and smooth accretion drive galaxy morphologic properties above $z > 1$. More specifically, we investigate how stellar densities, effective radii and shape parameters derived from the inertia tensor depend on mergers of different mass ratios. We find strong evidence that smooth accretion tends to flatten small galaxies over cosmic time, leading to the formation of disks. On the other hand, mergers, and not only the major ones, exhibit a propensit…
Explaining the internal distribution and motions of stars and gas in galaxies is a key aspect in understanding their evolution. In previous work we identified five well resolved galaxies with atypical kinematics from a cosmological simulation; two had kinematically distinct cores (KDCs), and three had counter-rotating gas and stars (CRGD). In this paper, we show that i) the KDC galaxies have flattening of stellar [O/Fe] at large galacto-centric radii due to the minor mergers that gave rise to the KDCs, and ii) the CRGD galaxies have an abrupt transition in the gas metallicity maps, from high m…
Using the redMaPPer cluster catalogue based on the Sloan Digital Sky Survey (SDSS) photometry, we investigate the importance of major mergers in the stellar mass build-up of brightest cluster galaxies (BCGs) between $0.08 \leq z \leq 0.50$. We use the SDSS spectroscopy, supplemented with spectroscopic observations from the Southern African Large Telescope at higher redshifts, to identify which BCGs and nearby companions are potential major merger candidates. We use the pair fraction as a proxy for the merger fraction in order to determine how much stellar mass growth the BCGs have experienced …
Two Mpc-size contact discontinuities have recently been identified in the XMM-Newton and Suzaku X-ray observations of the outskirts of the Perseus cluster (Walker et al. 2020). These structures have been tentatively interpreted as "sloshing cold fronts", which are customarily associated with differential motions of the cluster gas, perturbed by a merger. In this study we consider an alternative scenario, namely, that the most prominent discontinuity near the cluster virial radius is the result of the collision between the accretion shock and the "runaway" merger shock. We also discuss the poss…
Several types/classes of shocks naturally arise during formation and evolution of galaxy clusters. One such class is represented by accretion shocks, associated with deceleration of infalling baryons. Such shocks, characterized by a very high Mach number, are present even in 1D models of cluster evolution. Another class is composed of "runaway merger shocks", which appear when a merger shock, driven by a sufficiently massive infalling subcluster, propagates away from the main-cluster center. We argue that, when the merger shock overtakes the accretion shock, a new long-living shock is formed t…
We investigate the role of galaxy mergers on supermassive black hole (SMBH) accretion and star formation quenching in three state-of-the-art cosmological simulations with contrasting physics models: EAGLE, Illustris and IllustrisTNG. We find that recently coalesced 'post-mergers' in all three simulations have elevated SMBH accretion rates by factors of ~2-5. However, rapid (within 500 Myr of coalescence) quenching of star formation is rare, with incidence rates of 0.4% in Illustris, 4.5% in EAGLE and 10% in IllustrisTNG. The rarity of quenching in post-mergers results from substantial gas rese…
The formation mechanism of supermassive black holes (SMBHs) in general, and of $\sim 10^9\,{\rm M}_{\odot}$ SMBHs observed as luminous quasars at redshifts $z> 6$ in particular, remains an open fundamental question. The presence of such massive BHs at such early times, when the Universe was less than a billion years old, implies that they grew via either super-Eddington accretion, or nearly uninterrupted gas accretion near the Eddington limit; the latter, at first glance, is at odds with empirical trends at lower redshifts, where quasar episodes associated with rapid BH growth are rare and bri…
In major galaxy mergers, the orbits of stars are violently perturbed, and gas is torqued to the centre, diluting the gas metallicity and igniting a starburst. In this paper, we study the gas dynamics in and around merging galaxies using a series of cosmological magneto-hydrodynamical (MHD) zoom-in simulations. We find that the gas bridge connecting the merging galaxies pre-coalescence is dominated by turbulent pressure, with turbulent Mach numbers peaking at values of 1.6-3.3. This implies that bridges are dominated by supersonic turbulence, and are thus ideal candidates for studying the impac…
Research over the past decade has shown diminishing empirical evidence for major galaxy mergers being a dominating or even important mechanism for the growth of supermassive black holes in galaxies and the triggering of optically or X-ray selected active galactic nuclei (AGN). We here for the first time test whether such a connection exists at least in the most plausible part of parameter space for this mechanism: the highest specific accretion rate broad-line AGNs at the peak epoch of black hole activity around z = 2. To that end we examine 21 galaxies hosting a high accreting black hole (L/L…
We study supermassive black holes (BHs) in merging galaxies, using a suite of hydrodynamical simulations with very high spatial (~10 pc) and temporal (~1 Myr) resolution, where we vary the initial mass ratio, the orbital configuration, and the gas fraction. (i) We address the question of when and why, during a merger, increased BH accretion occurs, quantifying gas inflows and BH accretion rates. (ii) We also quantify the relative effectiveness in inducing AGN activity of merger-related versus secular-related causes, by studying different stages of the encounter: the stochastic (or early) stage…
The kinematic disturbances associated with major galaxy mergers are known to produce gas inflows, which in turn may trigger accretion onto the supermassive black holes (SMBH) of the participant galaxies. While this effect has been studied in galaxy pairs, the frequency of active galactic nuclei (AGN) in fully coalesced post-merger systems is poorly constrained due to the limited size or impurity of extant post-merger samples. Previously, we combined convolutional neural network (CNN) predictions with visual classifications to identify a highly pure sample of 699 post-mergers in deep r-band ima…
We present post-Newtonian $N$-body simulations on mergers of accreting stellar-mass black holes (BHs), where such general relativistic effects as the pericenter shift and gravitational wave (GW) emission are taken into consideration. The attention is concentrated on the effects of the dynamical friction and the Hoyle-Lyttleton mass accretion by ambient gas. We consider a system composed of ten BHs with initial mass of $30~M_\odot$. As a result, we show that mergers of accreting stellar-mass BHs are classified into four types: a gas drag-driven, an interplay-driven, a three body-driven, or an a…
Local galaxies with specific star-formation rates (star-formation rate per unit mass; sSFR~0.2-10/Gyr) as high as distant galaxies (z~1-3), are very rich in HI. Those with low stellar masses, log M_star (M_sun)=8-9, for example, have M_HI/M_star~5-30. Using continuity arguments of Peng et al. (2014), whereby the specific merger rate is hypothesized to be proportional to the specific star-formation rate, and HI gas mass measurements for local galaxies with high sSFR, we estimate that moderate mass galaxies, log M_star (M_sun)=9-10.5, can acquire sufficient gas through minor mergers (stellar mas…
The ages and metallicities of globular clusters (GCs) are known to be powerful tracers of the properties of their progenitor galaxies, enabling their use in determining the merger histories of galaxies. However, while useful in separating GCs into individual accretion events, the orbits of GC groups themselves have received less attention as probes of their progenitor galaxy properties. In this work, we use simulations of galaxies and their GC systems from the E-MOSAICS project to explore how the present-day orbital properties of GCs are related to the properties of their progenitor galaxies. …
Stellar halos in early-type galaxies (ETGs) are shaped by their accretion and merger histories. We use a sample of 1114 ETGs in the TNG100 simulation with stellar masses $10^{10.3}\leq M_{*}/M_\odot\leq 10^{12}$, selected at z=0 within the range of g-r colour and lambda-ellipticity diagram populated by observed ETGs. We study how the rotational support and intrinsic shapes of the stellar halos depend on the fraction of accreted stars, overall and separately by major, minor, and mini mergers. Accretion histories in TNG100 ETGs as well as the radial distributions of ex-situ stars $f_{ex}(R)$ str…
The role of major mergers in triggering super-Eddington accretion
Dipartimento di Fisica, “Sapienza” Università di Roma（罗马大学物理系）；INAF, Osservatorio Astronomico di Roma（罗马天文台）；INFN, Sezione Roma1（罗马第一国家核物理研究所）；Sapienza School for Advanced Studies（萨皮恩扎高等研究学院）；Como Lake Center for Astrophysics, DiSAT, Università degli Studi dell’Insubria（因苏布里亚大学迪萨特科莫湖天体物理学中心）；INFN, Sezione di Milano-Bicocca（米兰比可卡国家核物理研究所）；INAF, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（博洛尼亚空间天体物理学与科学天文台）
Recent observations of AGN activity in massive galaxies (log Mstar / Msun > 10.4) show that: 1) at z < 1, AGN-hosting galaxies do not show enhanced merger signatures compared to normal galaxies, 2) also at z < 1, most AGNs are hosted by quiescent galaxies; and 3) at z > 1, percentage of AGNs in star forming galaxies increases and becomes comparable to AGN percentage in quiescent galaxies at z ~ 2. How can major mergers explain AGN activity in massive quiescent galaxies which have no merger features and no star formation to indicate recent galaxy merger? By matching merger events in a cosmologi…
Neutron star mergers are believed to occur in accretion disks around supermassive black holes. Here we show that a putative jet launched from the merger of a binary neutron star (BNS) or a neutron star--black hole (NSBH) merger occurring at the migration trap in an active galactic nucleus (AGN) disk would be choked. The jet energy is deposited within the disk materials to power a hot cocoon. The cocoon is energetic enough to break out from the AGN disk and produce a bright X-ray shock breakout transient peaking at $\sim0.15\,{\rm d}$ after the merger. The peak luminosity is estimated as $\sim …
Accretion disks around supermassive black holes (SMBH) are promising sites for stellar mass black hole (BH) mergers due to mass segregation and merger acceleration by disk gas torques. Here we show that a GW-kick at BH merger causes ram-pressure stripping of gas within the BH Hill sphere. If $R_{H}\geq H$, the disk height, an off-center UV flare at $a_{\rm BH} \sim 10^{3}r_{g}$ emerges within $t_{\rm UV} \sim \rm{O}(2 {\rm days})(a_{\rm BH}/10^{3}r_{g})(M_{\rm SMBH}/10^{8}M_{\odot})(v_{\rm kick}/10^{2}\rm{km/s})$ post-merger and lasts O$(R_{H}/v_{\rm kick}) \sim \rm{O}(5 t_{\rm UV}$). The flar…
In this paper we continue the first ever study of magnetized mini-disks coupled to circumbinary accretion in a supermassive binary black hole (SMBBH) approaching merger reported in Bowen et al. 2018. We extend this simulation from 3 to 12 binary orbital periods. We find that relativistic SMBBH accretion acts as a resonant cavity, where quasi-periodic oscillations tied to the the frequency at which the black hole's orbital phase matches a non-linear $m=1$ density feature, or ``lump'', in the circumbinary accretion disk permeate the system. The rate of mass accretion onto each of the mini-disks …
We use the SDSS Stripe 82 to empirically quantify the stellar-mass and black-hole growth triggered by minor mergers in local spiral (disk) galaxies. Since major mergers destroy disks and create spheroids, morphologically disturbed spirals are likely remnants of minor mergers. Disturbed spirals exhibit enhanced specific star formation rates (SSFRs), the enhancement increasing in galaxies of 'later' morphological type (which have more gas and smaller bulges). By combining the SSFR enhancements with the fraction of time spirals spend in this 'enhanced' mode, we estimate that ~40% of the star form…
Many galaxies are expected to harbor binary supermassive black holes (SMBHs) in their centers. Their interaction with the surrounding gas results in accretion and exchange of angular momentum via tidal torques, facilitating binary inspiral. Here we explore the non-trivial coupling between these two processes and analyze how the global properties of externally supplied circumbinary disks depend on the binary accretion rate. By formulating our results in terms of the angular momentum flux driven by internal stresses, we come up with a very simple classification of the possible global disk struct…
The Environmental Switch in Black Hole Feeding: Bar-Driven vs. Merger-Driven Growth in IllustrisTNG50
Indian Institute of Science, Education and Research (IISER) Tirupati（印度科学教育与研究学院提鲁帕蒂分校）；Department of Space, Platenary and Astronomical Science and Engineering, Indian Institute of Technology (IIT), Kanpur（坎普尔印度理工学院空间、行星与天文学科学与工程系）
Black holes across a broad range of masses play a key role in the evolution of galaxies. The initial seeds of black holes formed at $z \sim 30$ and grew over cosmic time by gas accretion and mergers. Using observational data for quasars and theoretical models for the hierarchical assembly of dark matter halos, we study the relative importance of gas accretion and mergers for black hole growth, as a function of redshift ($0<z<10$) and black hole mass ($ 10^3 \, \mathrm{M_{\odot}} < M_{\bullet} < 10^{10} \, \mathrm{M_{\odot}}$). We find that (i) growth by accretion is dominant in a large fractio…
The recently discovered gravitational wave sources GW190521 and GW190814 have shown evidence of BH mergers with masses and spins that could be outside of the range expected from isolated stellar evolution. These merging objects could have undergone previous mergers. Such hierarchical mergers are predicted to be frequent in active galactic nuclei (AGN) disks, where binaries form and evolve efficiently by dynamical interactions and gaseous dissipation. Here we compare the properties of these observed events to the theoretical models of mergers in AGN disks, which are obtained by performing one-d…
We present the first fully relativistic prediction of the electromagnetic emission from the surrounding gas of a supermassive binary black hole system approaching merger. Using a ray-tracing code to post-process data from a general relativistic 3-d MHD simulation, we generate images and spectra, and analyze the viewing angle dependence of the light emitted. When the accretion rate is relatively high, the circumbinary disk, accretion streams, and mini-disks combine to emit light in the UV/EUV bands. We posit a thermal Compton hard X-ray spectrum for coronal emission; at high accretion rates, it…
Binary black hole (BBH) mergers are the primary sources of gravitational wave (GW) events detected by LIGO/Virgo. Binary black holes embedded in the accretion discs of active galactic nuclei (AGN) are possible candidates for such GW events. We develop an idealised analytic model for the orbital evolution of BBHs in AGN accretion discs by combining the evolution equations of disc-binary interaction and GW inspiral. We investigate the coupled `disc+GW'-driven evolution of BBHs transitioning from the disc-driven regime at large orbital separations into the GW-driven regime at small separations. I…
When following the growth of structure in the Universe, we propose replacing merger trees with merger graphs, in which haloes can both merge and split into separate pieces. We show that this leads to smoother mass growth and eliminates catastrophic failures in which massive haloes have no progenitors or descendants. For those who prefer to stick with merger trees, we find that trees derived from our merger graphs have similar mass growth properties to previous methods, but again without catastrophic failures. For future galaxy formation modelling, two different density thresholds can be used t…
3D simulations of high mass young stellar object (HMYSO) growth show that their circumstellar discs fragment onto multiple self-gravitating objects. Accretion of these by HMYSO may explain episodic accretion bursts discovered recently. We post-process results of a previous 3D simulation of a HMYSO disc with a 1D code that resolves the disc and object dynamics down to the stellar surface. We find that burst-like deposition of material into the inner disc seen in 3D simulations by itself does not always signify powerful accretion bursts. Only high density post-collapse clumps crossing the inner …
We apply our recently proposed "quadratic genetic modification" approach to generating and testing the effects of alternative mass accretion histories for a single $Λ$CDM halo. The goal of the technique is to construct different formation histories, varying the overall contribution of mergers to the fixed final mass. This enables targeted studies of galaxy and dark matter halo formation's sensitivity to the smoothness of mass accretion. Here, we focus on two dark matter haloes, each with four different mass accretion histories. We find that the concentration of both haloes systematically decre…
We make black hole (BH) merger trees from Millennium and Millennium-II simulations to find under what conditions 10^9Msun SMBH can form by redshift z=7. In order to exploit both: large box size in the Millennium simulation; and large mass resolution in the Millennium-II simulation, we develop a method to combine these two simulations together, and use the Millennium-II merger trees to predict the BH seeds to be used in the Millennium merger trees. We run multiple semi-analytical simulations where SMBHs grow through mergers and episodes of gas accretion triggered by major mergers. As a constrai…
The growth of galaxies is a key problem in understanding the structure and evolution of the universe. Galaxies grow their stellar mass by a combination of star formation and mergers, with a relative importance that is redshift dependent. Theoretical models predict quantitatively different contributions from the two channels; measuring these from the data is a crucial constraint. Exploiting the UltraVISTA catalog and a unique sample of progenitors of local ultra massive galaxies selected with an abundance matching approach, we quantify the role of the two mechanisms from z=2 to 0. We also compa…
Gas Accretion versus BH Merger driven Growth Modes of Supermassive Black Holes and Implications for the Little Red Dots
Istituto Nazionale di Astrofisica (INAF) - Osservatorio Astronomico di Trieste (OATs)（意大利国家天体物理研究所（INAF）- 的里雅斯特天文台（OATs））；Centro de Ciências Naturais e Humanas - Universidade Federal do ABC（自然与人类科学中心 - 圣保罗联邦ABC大学）；Núcleo de Astrofísica - Universidade Cidade de São Paulo（天体物理学核心 - 圣保罗城市大学）
The origin of supermassive black holes (with $\gtrsim\!10^9\,M_{\odot}$) in the early universe (redshift $z \sim 7$) remains poorly understood. Gravitational collapse of a massive primordial gas cloud is a promising initial process, but theoretical studies have difficulty growing the black hole fast enough. We focus on the magnetic effects on star formation that occurs in an atomic-cooling gas cloud. Using a set of three-dimensional magnetohydrodynamic (MHD) simulations, we investigate the star formation process in the magnetized atomic-cooling gas cloud with different initial magnetic field s…
We have developed a new tool to analyse galaxies in the EAGLE simulations as close as possible to observations.We investigated the evolution of their kinematic properties by means of the angular momentum proxy parameter,$ λ_{Re} $for galaxies with $M_{*} \ge 5 \times 10^{9} M_{\odot}$ in the RefL0100N1504 simulation up to redshift two (z = 2). Galaxies in the simulation show a wide variety of kinematic features, similiar to those found in integral-field spectroscopic studies. At z=0 the distribution of galaxies in the $λ_{Re}-ε$ plane is also in good agreement with results from observations. S…
