arXiv subjects

Yueying Ni

Publications and source records attributed to Yueying Ni.

At least 73 records · Page 4Linked to original sources

arXiv2022

Statistics of Galactic-Scale Quasar Pairs at Cosmic Noon

The statistics of galactic-scale quasar pairs can elucidate our understanding of the dynamical evolution of supermassive black hole (SMBH) pairs, the duty cycles of quasar activity in mergers, or even the nature of dark matter, but have been challenging to measure at cosmic noon, the prime epoch of massive galaxy and SMBH formation. Here we measure a double quasar fraction of $\sim 6.2\pm0.5\times 10^{-4}$ integrated over $\sim 0.3-3$ arcsec separations (projected physical separations of $\sim 3-30\,{\rm kpc}$ at $z\sim 2$) in luminous ($L_{\rm bol}>10^{45.8}\,{\rm erg\,s^{-1}}$) unobscured quasars at $1.5<z<3.5$, using Gaia EDR3-resolved pairs around SDSS DR16 quasars. The measurement was based on a sample of 60 Gaia-resolved double quasars (out of 487 Gaia pairs dominated by quasar+star superpositions) at these separations, corrected for pair completeness in Gaia, which we quantify as functions of pair separation, magnitude of the primary, and magnitude contrast. The double quasar fraction increases towards smaller separations by a factor of $\sim 5$ over these scales. The division between physical quasar pairs and lensed quasars in our sample is currently unknown, requiring dedicated follow-up observations (in particular, deep, sub-arcsec-resolution IR imaging for the closest pairs). Intriguingly, at this point the observed pair statistics are in rough agreement with theoretical predictions both for the lensed quasar population in mock catalogs and for dual quasars in cosmological hydrodynamic simulations. Upcoming wide-field imaging/spectroscopic space missions such as Euclid, CSST and Roman, combined with targeted follow-up observations, will conclusively measure the abundances and host galaxy properties of galactic-scale quasar pairs, offset AGNs, and sub-arcsec lensed quasars across cosmic time.

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arXiv2022

Probing the $z\gtrsim6$ quasars in a universe with IllustrisTNG physics: Impact of gas-based black hole seeding models

We explore implications of a range of black hole (BH) seeding prescriptions on the formation of the brightest $z\gtrsim6$ quasars in cosmological hydrodynamic simulations. The underlying galaxy formation model is the same as in IllustrisTNG. Using constrained initial conditions, we study the growth of BHs in rare overdense regions (forming $\gtrsim10^{12}M_{\odot}/h$ halos by $z=7$) using a $(9~\mathrm{Mpc}/h)^3$ simulated volume. BH growth is maximal within halos that are compact and have a low tidal field. For these halos, we consider an array of gas-based seeding prescriptions wherein $M_{\mathrm{seed}}=10^4-10^6~M_{\odot}/h$ seeds are inserted in halos above critical thresholds for halo mass and dense, metal-poor gas mass (defined as $\tilde{M}_{\mathrm{h}}$ and $\tilde{M}_{\mathrm{sf,mp}}$, respectively, in units of $M_{\mathrm{seed}}$). We find that a seed model with $\tilde{M}_{\mathrm{sf,mp}}=5$ and $\tilde{M}_{\mathrm{h}}=3000$ successfully produces a $z\sim6$ quasar with $\sim10^9~M_{\odot}$ mass and $\sim10^{47}~\mathrm{ergs~s^ {-1}}$ luminosity. BH mergers play a crucial role at $z\gtrsim9$, causing an early boost in BH mass at a time when accretion-driven BH growth is negligible. When more stringent seeding conditions are applied (for e.g., $\tilde{M}_{\mathrm{sf,mp}}=1000$), the relative paucity of BH seeds results in a much lower merger rate. In this case, $z\gtrsim6$ quasars can only be formed if we enhance the maximum allowed BH accretion rates (by factors $\gtrsim10$) compared to the accretion model used in IllustrisTNG. This can be achieved either by allowing for super-Eddington accretion, or by reducing the radiative efficiency. Our results show that progenitors of $z\sim6$ quasars have distinct BH merger histories for different seeding models, which will be distinguishable with LISA observations.

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arXiv2022

The ASTRID Simulation: Galaxy Formation and Reionization

We introduce the ASTRID simulation, a large-scale cosmological hydrodynamic simulation in a $250$ Mpc/h box with $2\times 5500^3$ particles. ASTRID contains a large number of high redshift galaxies, which can be compared to future survey data, and resolves galaxies in halos more massive than $2\times 10^9 M_\odot$. ASTRID has been run from $z=99$ to $z=3$. As a particular focus is modelling the high redshift Universe, it contains models for inhomogeneous hydrogen and helium reionization, baryon relative velocities and massive neutrinos, as well as supernova and AGN feedback. The black hole model includes mergers driven by dynamical friction rather than repositioning. We briefly summarise the implemented models, and the technical choices we took when developing the simulation code. We validate the model, showing good agreement with observed UV luminosity functions, galaxy stellar mass functions and specific star formation rates. We show that the redshift at which a given galaxy underwent hydrogen reionization has a large effect on the halo gas fraction. Finally, at $z=6$, halos with $M \sim 2\times 10^9 M_\odot$ which have been reionized have a star formation rate $1.5$ times greater than those which have not yet been reionized.

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arXiv2022

The ASTRID simulation: the evolution of Supermassive Black Holes

We present the evolution of black holes (BHs) and their relationship with their host galaxies in Astrid, a large-volume cosmological hydrodynamical simulation with box size 250 $h^{-1} \rm Mpc$ containing $2\times5500^3$ particles evolved to z=3. Astrid statistically models BH gas accretion and AGN feedback to their environments, applies a power-law distribution for BH seed mass $M_{\rm sd}$, uses a dynamical friction model for BH dynamics and executes a physical treatment of BH mergers. The BH population is broadly consistent with empirical constraints on the BH mass function, the bright end of the luminosity functions, and the time evolution of BH mass and accretion rate density. The BH mass and accretion exhibit a tight correlation with host stellar mass and star formation rate. We trace BHs seeded before z>10 down to z=3, finding that BHs carry virtually no imprint of the initial $M_{\rm sd}$ except those with the smallest $M_{\rm sd}$, where less than 50\% of them have doubled in mass. Gas accretion is the dominant channel for BH growth compared to BH mergers. With dynamical friction, Astrid predicts a significant delay for BH mergers after the first encounter of a BH pair, with a typical elapse time of about 200 Myrs. There are in total $4.5 \times 10^5$ BH mergers in Astrid at z>3, $\sim 10^3$ of which have X-ray detectable EM counterparts: a bright kpc scale dual AGN with $L_X>10^{43}$ erg/s. BHs with $M_{\rm BH} \sim 10^{7-8} M_{\odot}$ experience the most frequent mergers. Galaxies that host BH mergers are unbiased tracers of the overall $M_{\rm BH} - M_{*}$ relation. Massive ($>10^{11} M_{\odot}$) galaxies have a high occupation number (>10) of BHs, and hence host the majority of BH mergers.

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arXiv2022

The Impact of Dust on the Sizes of Galaxies in the Epoch of Reionization

We study the sizes of galaxies in the Epoch of Reionization using a sample of ~100,000 galaxies from the BlueTides cosmological hydrodynamical simulation from z=7 to 11. We measure the galaxy sizes from stellar mass and luminosity maps, defining the effective radius as the minimum radius which could enclose the pixels containing 50% of the total mass/light in the image. We find an inverse relationship between stellar mass and effective half-mass radius, suggesting that the most massive galaxies are more compact and dense than lower mass galaxies, which have flatter mass distributions. We find a mildly negative relation between intrinsic far-ultraviolet luminosity and size, while we find a positive size-luminosity relation when measured from dust-attenuated images. This suggests that dust is the predominant cause of the observed positive size-luminosity relation, with dust preferentially attenuating bright sight lines resulting in a flatter emission profile and thus larger measured effective radii. We study the size-luminosity relation across the rest-frame ultraviolet and optical, and find that the slope decreases at longer wavelengths; this is a consequence of the relation being caused by dust, which produces less attenuation at longer wavelengths. We find that the far-ultraviolet size-luminosity relation shows mild evolution from z=7 to 11, and galaxy size evolves with redshift as $R\propto(1+z)^{-m}$, where $m=0.662\pm0.009$. Finally, we investigate the sizes of z=7 quasar host galaxies, and find that while the intrinsic sizes of quasar hosts are small relative to the overall galaxy sample, they have comparable sizes when measured from dust-attenuated images.

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arXiv2022

The CAMELS project: public data release

The Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) project was developed to combine cosmology with astrophysics through thousands of cosmological hydrodynamic simulations and machine learning. CAMELS contains 4,233 cosmological simulations, 2,049 N-body and 2,184 state-of-the-art hydrodynamic simulations that sample a vast volume in parameter space. In this paper we present the CAMELS public data release, describing the characteristics of the CAMELS simulations and a variety of data products generated from them, including halo, subhalo, galaxy, and void catalogues, power spectra, bispectra, Lyman-$α$ spectra, probability distribution functions, halo radial profiles, and X-rays photon lists. We also release over one thousand catalogues that contain billions of galaxies from CAMELS-SAM: a large collection of N-body simulations that have been combined with the Santa Cruz Semi-Analytic Model. We release all the data, comprising more than 350 terabytes and containing 143,922 snapshots, millions of halos, galaxies and summary statistics. We provide further technical details on how to access, download, read, and process the data at \url{https://camels.readthedocs.io}.

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arXiv2021

Massive Black Hole Mergers with Orbital Information: Predictions from the ASTRID Simulation

We examine massive black hole (MBH) mergers and their associated gravitational wave signals from the large-volume cosmological simulation Astrid. Astrid includes galaxy formation and black hole models recently updated with a MBH seed population between $3\times 10^4M_{\odot}/h$ and $3\times 10^5M_{\odot}/h$ and a sub-grid dynamical friction (DF) model to follow the MBH dynamics down to $1.5\;\text{ckpc}/h$. We calculate initial eccentricities of MBH orbits directly from the simulation at kpc-scales, and find orbital eccentricities above $0.7$ for most MBH pairs before the numerical merger. After approximating unresolved evolution on scales below ${\sim 200\,\text{pc}}$, we find that the in-simulation DF on large scales accounts for more than half of the total orbital decay time ($\sim 500\,\text{Myrs}$) due to DF. The binary hardening time is an order of magnitude longer than the DF time, especially for the seed-mass binaries ($M_\text{BH}<2M_\text{seed}$). As a result, only $\lesssim20\%$ of seed MBH pairs merge at $z>3$ after considering both unresolved DF evolution and binary hardening. These $z>3$ seed-mass mergers are hosted in a biased population of galaxies with the highest stellar masses of $>10^9\,M_\odot$. With the higher initial eccentricity prediction from Astrid, we estimate an expected merger rate of $0.3-0.7$ per year from the $z>3$ MBH population. This is a factor of $\sim 7$ higher than the prediction using the circular orbit assumption. The LISA events are expected at a similar rate, and comprise $\gtrsim 60\%$ seed-seed mergers, $\sim 30\%$ involving only one seed-mass MBH, and $\sim 10\%$ mergers of non-seed MBHs.

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arXiv2021

Not all peaks are created equal: the early growth of Supermassive Black Holes

In this work, we use the constrained Gaussian realization technique to study the early growth of supermassive black holes (SMBHs) in cosmological hydrodynamic simulations, exploring its relationship with features of the initial density peaks on large scales, ~1 Mpc/h. Our constrained simulations of volume (20 Mpc/h)^3 successfully reconstruct the large-scale structure as well as the black hole growth for the hosts of the rare 10^9 Msun SMBHs found in the BlueTides simulation at z~7. We run a set of simulations with constrained initial conditions by imposing a 5 σ_0(R_G) peak on scale of R_G = 1 Mpc/h varying different peak features, such as the shape and compactness as well as the tidal field surrounding the peak. We find that initial density peaks with high compactness and low tidal field induce the most rapid BH growth at early epochs. This is because compact density peaks with a more spherical large scale matter distribution lead to the formation of high density gas clumps in the centers of halos, and thus boost early BH accretion. Moreover, such initially compact density peaks in low tidal field regions also lead to a more compact BH host galaxy morphology. This can explain the tight correlation between BH growth and host galaxy compactness seen in observations.

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arXiv2021

AI-assisted super-resolution cosmological simulations II: Halo substructures, velocities and higher order statistics

In this work, we expand and test the capabilities of our recently developed super-resolution (SR) model to generate high-resolution (HR) realizations of the full phase-space matter distribution, including both displacement and velocity, from computationally cheap low-resolution (LR) cosmological N-body simulations. The SR model enhances the simulation resolution by generating 512 times more tracer particles, extending into the deeply non-linear regime where complex structure formation processes take place. We validate the SR model by deploying the model in 10 test simulations of box size 100 Mpc/h, and examine the matter power spectra, bispectra and 2D power spectra in redshift space. We find the generated SR field matches the true HR result at percent level down to scales of k ~ 10 h/Mpc. We also identify and inspect dark matter halos and their substructures. Our SR model generate visually authentic small-scale structures, that cannot be resolved by the LR input, and are in good statistical agreement with the real HR results. The SR model performs satisfactorily on the halo occupation distribution, halo correlations in both real and redshift space, and the pairwise velocity distribution, matching the HR results with comparable scatter, thus demonstrating its potential in making mock halo catalogs. The SR technique can be a powerful and promising tool for modelling small-scale galaxy formation physics in large cosmological volumes.

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arXiv2021

The Diversity of Environments Around Luminous Quasars at Redshift $z \sim 6$

Significant clustering around the rarest luminous quasars is a feature predicted by dark matter theory combined with number density matching arguments. However, this expectation is not reflected by observations of quasars residing in a diverse range of environments. Here, we assess the tension in the diverse clustering of visible $i$-band dropout galaxies around luminous $z\sim6$ quasars. Our approach uses a simple empirical method to derive the median luminosity to halo mass relation, $L_{c}(M_{h})$ for both quasars and galaxies under the assumption of log-normal luminosity scatter, $Σ_{Q}$ and $Σ_{G}$. We show that higher $Σ_{Q}$ reduces the average halo mass hosting a quasar of a given luminosity, thus introducing at least a partial reversion to the mean in the number count distribution of nearby Lyman-Break galaxies. We generate a large sample of mock Hubble Space Telescope fields-of-view centred across rare $z\sim6$ quasars by resampling pencil beams traced through the dark matter component of the BlueTides cosmological simulation. We find that diverse quasar environments are expected for $Σ_{Q}>0.4$, consistent with numerous observations and theoretical studies. However, we note that the average number of galaxies around the central quasar is primarily driven by galaxy evolutionary processes in neighbouring halos, as embodied by our parameter $Σ_{G}$, instead of a difference in the large scale structure around the central quasar host, embodied by $Σ_{Q}$. We conclude that models with $Σ_{G}>0.3$ are consistent with current observational constraints on high-z quasars, and that such a value is comparable to the scatter estimated from hydrodynamical simulations of galaxy formation.

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arXiv2021

Observing the host galaxies of high-redshift quasars with JWST: predictions from the BlueTides simulation

The bright emission from high-redshift quasars completely conceals their host galaxies in the rest-frame ultraviolet/optical, with detection of the hosts in these wavelengths eluding even the Hubble Space Telescope (HST) using detailed point spread function (PSF) modelling techniques. In this study we produce mock images of a sample of z=7 quasars extracted from the BlueTides simulation, and apply Markov Chain Monte Carlo-based PSF modelling to determine the detectability of their host galaxies with the James Webb Space Telescope (JWST). While no statistically significant detections are made with HST, we predict that at the same wavelengths and exposure times JWST NIRCam imaging will detect ~50% of quasar host galaxies. We investigate various observational strategies, and find that NIRCam wide-band imaging in the long-wavelength filters results in the highest fraction of successful quasar host detections, detecting >80% of the hosts of bright quasars in exposure times of 5 ks. Exposure times of ~5 ks are required to detect the majority of host galaxies in the NIRCam wide-band filters, however even 10 ks exposures with MIRI result in <30% successful host detections. We find no significant trends between galaxy properties and their detectability. The PSF modelling can accurately recover the host magnitudes, radii, and spatial distribution of the larger-scale emission, when accounting for the central core being contaminated by residual quasar flux. Care should be made when interpreting the host properties measured using PSF modelling.

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arXiv2021

AI-assisted super-resolution cosmological simulations

Cosmological simulations of galaxy formation are limited by finite computational resources. We draw from the ongoing rapid advances in Artificial Intelligence (specifically Deep Learning) to address this problem. Neural networks have been developed to learn from high-resolution (HR) image data, and then make accurate super-resolution (SR) versions of different low-resolution (LR) images. We apply such techniques to LR cosmological N-body simulations, generating SR versions. Specifically, we are able to enhance the simulation resolution by generating 512 times more particles and predicting their displacements from the initial positions. Therefore our results can be viewed as new simulation realizations themselves rather than projections, e.g., to their density fields. Furthermore, the generation process is stochastic, enabling us to sample the small-scale modes conditioning on the large-scale environment. Our model learns from only 16 pairs of small-volume LR-HR simulations, and is then able to generate SR simulations that successfully reproduce the HR matter power spectrum to percent level up to $16\,h^{-1}\mathrm{Mpc}$, and the HR halo mass function to within $10 \%$ down to $10^{11} \, M_\odot$. We successfully deploy the model in a box 1000 times larger than the training simulation box, showing that high-resolution mock surveys can be generated rapidly. We conclude that AI assistance has the potential to revolutionize modeling of small-scale galaxy formation physics in large cosmological volumes.

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arXiv2021

Dynamical Friction Modeling of Massive Black Holes in Cosmological Simulations and Effects on Merger Rate Predictions

In this work we establish and test methods for implementing dynamical friction for massive black hole pairs that form in large volume cosmological hydrodynamical simulations which include galaxy formation and black hole growth. We verify our models and parameters both for individual black hole dynamics and for the black hole population in cosmological volumes. Using our model of dynamical friction (DF) from collisionless particles, black holes can effectively sink close to the galaxy center, provided that the black hole's dynamical mass is at least twice that of the lowest mass resolution particles in the simulation. Gas drag also plays a role in assisting the black holes' orbital decay, but it is typically less effective than that from collisionless particles, especially after the first billion years of the black hole's evolution. DF from gas becomes less than $1\%$ of DF from collisionless particles for BH masses $> 10^{7}$ M$_{\odot}$. Using our best DF model, we calculate the merger rate down to $z=1.1$ using an $L_{\rm box}=35$ Mpc$/h$ simulation box. We predict $\sim 2$ mergers per year for $z>1.1$ peaking at $z\sim 2$. These merger rates are within the range obtained in previous work using similar-resolution hydro-dynamical simulations. We show that the rate is enhanced by factor of $\sim 2$ when DF is taken into account in the simulations compared to the no-DF run. This is due to $>40\%$ more black holes reaching the center of their host halo when DF is added.

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arXiv2020

The host galaxies of z=7 quasars: predictions from the BlueTides simulation

We examine the properties of the host galaxies of $z=7$ quasars using the large volume, cosmological hydrodynamical simulation BlueTides. We find that the 10 most massive black holes and the 191 quasars in the simulation (with $M_{\textrm{UV,AGN}} 10^{6.5}M_\odot$ black hole, indicating that minor mergers play at least some role in growing black holes in the early Universe.

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arXiv2020

The early growth of supermassive black holes in cosmological hydrodynamic simulations with constrained Gaussian realizations

The paper examines the early growth of supermassive black holes (SMBHs) in cosmological hydrodynamic simulations with different BH seeding scenarios. Employing the constrained Gaussian realization, we reconstruct the initial conditions in the large-volume BlueTides simulation and run them to $z=6$ to cross-validate that the method reproduces the first quasars and their environments. Our constrained simulations in a volume of $(15\, h^{-1}{\rm Mpc})^3$ successfully recover the evolution of large-scale structure and the stellar and BH masses in the vicinity of a $\sim10^{12}\, M_{\odot}$ halo which we identified in BlueTides at $z\sim7$ hosting a $\sim10^9\, M_{\odot}$ SMBH. Among our constrained simulations, only the ones with a low-tidal field and high-density peak in the initial conditions induce the fastest BH growth required to explain the $z>6$ quasars. We run two sets of simulations with different BH seed masses of $5\times10^3$, $5\times10^4$, and $5\times10^5\, h^{-1}M_{\odot}$, (a) with the same ratio of halo to BH seed mass and (b) with the same halo threshold mass. At $z=6$, all the SMBHs converge in mass to $\sim10^9\, M_{\odot}$ except for the one with the smallest seed in (b) undergoing critical BH growth and reaching $10^8$ -- $10^9\, M_{\odot}$, albeit with most of the growth in (b) delayed compared to set (a). The finding of eight BH mergers in the small-seed scenario (four with masses $10^4$ -- $10^6\, M_{\odot}$ at $z>12$), six in the intermediate-seed scenario, and zero in the large-seed scenario suggests that the vast BHs in the small-seed scenario merge frequently during the early phases of the growth of SMBHs. The increased BH merger rate for the low-mass BH seed and halo threshold scenario provides an exciting prospect for discriminating BH formation mechanisms with the advent of multi-messenger astrophysics and next-generation gravitational wave facilities.

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arXiv2019

QSO obscuration at high redshift ($z \gtrsim 7$): Predictions from the BlueTides simulation

High-$z$ AGNs hosted in gas rich galaxies are expected to grow through significantly obscured accretion phases. This may limit or bias their observability. In this work, we use \textsc{BlueTides}, a large volume cosmological simulation of galaxy formation to examine quasar obscuration for the highest-redshift ($z \geq 7$) supermassive black holes residing in the center of galaxies. We find that for the bright quasars, most of the high column density gas ($>90\%$) resides in the innermost regions of the host galaxy, (typically within $< 10$ ckpc), while the gas in the outskirts is a minor contributor to the $N_\mathrm H$. The brightest quasars can have large angular variations in galactic obscuration, over 2 orders of magnitude, where the lines of sight with the lowest obscuration are those formed via strong gas outflows driven by AGN feedback. We find that for the overall AGN population, the mean $N_\mathrm H$ is generally larger for high luminosity and BH mass, while the $N_\mathrm H$ distribution is significantly broadened, developing a low $N_\mathrm H $ wing due to the angular variations driven by the AGN outflows/feedback. The obscured fraction P($N_{\rm H} > 10^{23} {\rm cm}^{-2}$) typically range from 0.6 to 1.0 for increasing $L_{X}$ (with $L_X > 10^{43} \rm{ergs/s}$), with no clear trend of redshift evolution. With respect to the galaxy host property, we find a linear relation between $N_{\rm H}$, $M_*$ and $M_{\rm H_2}$ with $\log N_{\rm H} = (0.24 \pm 0.03) \log M_{*} + (20.7 \pm 0.3)$ and $\log N_{\rm H} = (0.47 \pm 0.03) \log M_{\rm H_2} + (18.4 \pm 0.3)$. The dust optical depth in the UV band $τ_{\mathrm UV}$ has tight positive correlation with $N_{\rm H}$. Our dust extincted UVLF is about 1.5 dex lower than the intrinsic UVLF, implying that more than 99\% of the $z \sim 7$ AGNs are heavily dust extincted and therefore would be missed by the UV band observation.

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arXiv2019

Predictions for the Abundance of High-redshift Galaxies in a Fuzzy Dark Matter Universe

During the last decades, rapid progress has been made in measurements of the rest-frame ultraviolet (UV) luminosity function (LF) for high-redshift galaxies ($z \geq 6$). The faint-end of the galaxy LF at these redshifts provides powerful constraints on different dark matter models that suppress small-scale structure formation. In this work we perform full hydrodynamical cosmological simulations of galaxy formation using an alternative DM model composed of extremely light bosonic particles ($m \sim 10^{-22}$ eV), also known as fuzzy dark matter (FDM), and examine the predictions for the galaxy stellar mass function and luminosity function at $z \geq 6$ for a range of FDM masses. We find that for FDM models with bosonic mass $m = 5\times10^{-22}$ eV, the number density of galaxies with stellar mass $\rm M_* \sim 10^7 M_{\odot}$ is suppressed by $\sim 40\%$ at z = 9, $\sim 20\%$ at z = 5, and the UV LFs within magnitude range of -16 < $M_{\rm UV}$ < -14 is suppressed by $\sim 60\%$ at $z = 9$, $\sim 20\%$ at $z = 5$ comparing to the CDM counterpart simulation. Comparing our predictions with current measurements of the faint-end LFs ($-18 \leqslant M_{\rm UV} \leqslant -14$), we find that FDM models with $m_{22} < 5\times10^{-22}$ are ruled out at $3σ$ confidence level. We expect that future LF measurements by James Webb Space Telescope (JWST), which will extend down to $M_{\rm UV} \sim -13$ for $z \lesssim 10$, with a survey volume that is comparable to the Hubble Ultra Deep Field (HUDF) would have the capability to constrain FDM models to $m\; \gtrsim 10^{-21}$ eV.

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arXiv2018

Gas outflows from the z= 7.54 quasar : predictions from the BlueTides Simulation

Many theoretical models predict that quasar driven outflows account for the observed quenching of star formation in massive galaxies. There is growing observational evidence for quasar-launched massive outflows at z>6, while the details of outflow-host galaxy interaction remain obscure. In this paper, we study the feedback around the highest redshift quasar in the BlueTides simulation, the largest volume cosmological hydrodynamic simulation so far carried out. We present predictions for gas outflows around the brightest $z = 7.54$ quasar which hosts the most massive black hole in the simulation volume, which has grown to black hole mass $6.7\times 10^{8}{\rm M}_\odot$ consistent with the current record holder for high-z quasars. We introduce a method to identify and trace the gas outflowing from the halo. We find that the total mass of the outflow gas is about $3.6\times 10^{9}{\rm M}_\odot$, constituting 6\% of the total gas in the halo. The outflow gas contains a cold, dense molecular component with mass about $2.6\times 10^{8}{\rm M}_\odot$, that originates from the inner region of the halo, within a few kpc of the central black hole. The velocities of the outflow gas reach thousands of km/s, within which the molecular component has mass averaged outward radial velocity of $1300$ km/s, consistent with observations. The averaged outflow rate is about $200-300 {\rm M}_\odot/yr$, with the outflowing gas mainly in a hotter ($T \sim 10^7$ K) and lower density state than the average of the host halo gas.

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