The Lyman-$α$ forest is a powerful probe for cosmology, but it is also strongly impacted by galaxy evolution and baryonic processes such as Active Galactic Nuclei (AGN) feedback, which can redistribute mass and energy on large scales. We constrain the signatures of AGN feedback on the 1D power spectrum of the Lyman-$α$ forest using a series of eight hydro-cosmological simulations performed with the Adaptative Mesh Refinement code RAMSES. This series starts from the Horizon-AGN simulation and varies the sub-grid parameters for AGN feeding, feedback and stochasticity. These simulations cover the whole plausible range of feedback and feeding parameters according to the resulting galaxy properties. AGNs globally suppress the Lyman-$α$ power at all scales. On large scales, the energy injection and ionization dominate over the supply of gas mass from AGN-driven galactic winds, thus suppressing power. On small scales, faster cooling of denser gas mitigates the suppression. This effect increases with decreasing redshift. We provide lower and upper limits of this signature at nine redshifts between $z=4.25$ and $z=2.0$, making it possible to account for it at post-processing stage in future work given that running simulations without AGN feedback can save considerable amounts of computing resources. Ignoring AGN feedback in cosmological inference analyses leads to strong biases with 2\% shift on $σ_8$ and 1\% shift on $n_s$, which represents twice the standards deviation of the current constraints on $n_s$.
Coronal-Line Forest Active Galactic Nuclei (CLiF AGN) are remarkable in the sense that they have a rich spectrum of dozens of coronal emission lines (e.g. [FeVII], [FeX] and [NeV]) in their spectra. Rose, Elvis & Tadhunter (2015) suggest that the inner obscuring torus wall is the most likely location of the coronal line region in CLiF AGN, and the unusual strength of the forbidden high ionization lines is due to a specific AGN-torus inclination angle. Here we test this suggestion using mid-IR colours (4.6$μ$m-22$μ$m) from the Wide-Field Infrared Survey Explorer (WISE) for the CLiF AGN. We use …
We study the sensitivity of the $z=0.1$ Lyman-$α$ Forest observables, such as the column density distribution function (CDD), flux PDF, flux power spectrum, and line width distribution, to sub-grid models of active galactic nuclei (AGN) feedback using the Illustris and IllustrisTNG (TNG) cosmological simulations. The two simulations share an identical Ultraviolet Background (UVB) prescription and similar cosmological parameters, but TNG features an entirely reworked AGN feedback model. Due to changes in the AGN radio mode model, the original Illustris simulations have a factor of 2-3 fewer Lym…
We study the effect of different feedback prescriptions on the properties of the low redshift ($z\leq1.6$) Ly$α$ forest using a selection of hydrodynamical simulations drawn from the Sherwood simulation suite. The simulations incorporate stellar feedback, AGN feedback and a simplified scheme for efficiently modelling the low column density Ly$α$ forest. We confirm a discrepancy remains between Cosmic Origins Spectrograph (COS) observations of the Ly$α$ forest column density distribution function (CDDF) at $z \simeq 0.1$ for high column density systems ($N_{\rm HI}>10^{14}\rm\,cm^{-2}$), as wel…
Active galactic nuclei (AGN) feedback models are generally calibrated to reproduce galaxy observables such as the stellar mass function and the bimodality in galaxy colors. We use variations of the AGN feedback implementations in the IllustrisTNG (TNG) and Simba cosmological hydrodynamic simulations to show that the low redshift Lyman-$α$ forest can provide constraints on the impact of AGN feedback. We show that TNG over-predicts the number density of absorbers at column densities $N_{\rm HI} < 10^{14}$ cm$^{-2}$ compared to data from the Cosmic Origins Spectrograph (in agreement with previous…
We introduce Coronal-Line Forest Active Galactic Nuclei (CLiF AGN), AGN which have a rich spectrum of forbidden high-ionization lines (FHILs, e.g. [FeVII], [FeX] and [NeV]), as well as relatively strong narrow ($\sim$300 km s$^{-1}$) H$α$ emission when compared to the other Balmer transition lines. We find that the kinematics of the CLiF emitting region are similar to those of the forbidden low-ionization emission-line (FLIL) region. We compare emission line strengths of both FHILs and FLILs to CLOUDY photoionization results and find that the CLiF emitting region has higher densities (10$^{4.5…
We investigate the effects of AGN heating and the ultraviolet background on the low-redshift Lyman-$α$ forest column density distribution (CDD) using the Illustris simulation. We show that Illustris reproduces observations at $z =0.1$ in the column density range $10^{12.5} - 10^{13.5}$cm$^{-2}$, relevant for the "photon underproduction crisis." We attribute this to the inclusion of AGN feedback, which changes the gas distribution so as to mimic the effect of extra photons, as well as the use of the Faucher-Giguère ultraviolet background, which is more ionizing at $z=0.1$ than the Haardt & Mada…
We present a model for the classification of Coronal-Line Forest Active Galactic Nuclei (CLiF AGN). CLiF AGN are of special interest due to their remarkably large number of emission lines, especially forbidden high ionization lines (FHILs). Rose et al. (2015a) suggest that their emission is dominated by reflection from the inner wall of the obscuring region rather than direct emission from the accretion disk. This makes CLiF AGN laboratories to test AGN-torus models. Modeling AGN as an accreting supermassive black hole, surrounded by a cylinder of dust and gas, we show a relationship between v…
Coronal-Line Forest Active Galactic Nuclei (CLiF AGN) are characterized by strong high-ionization lines, which contrast to what is found in most AGNs. Here, we carry out a multiwavelength analysis aimed at understanding the physical processes in the Narrow Line Region (NLR) of these objects and unveiling if they are indeed a special class of AGN. By comparing coronal emission-line ratios we conclude that there are no differences between CLiF and non-CLiF AGNs. We derive physical conditions of the narrow line region (NLR) gas and found electron densities in the range $3.6\times$10$^{2}$ - $1.7\…
Motivated by the claimed detection of a large population of faint active galactic nuclei (AGN) at high redshift, recent studies have proposed models in which AGN contribute significantly to the z > 4 H I ionizing background. In some models, AGN are even the chief sources of reionization. If correct, these models would make necessary a complete revision to the standard view that galaxies dominated the high-redshift ionizing background. It has been suggested that AGN-dominated models can better account for two recent observations that appear to be in conflict with the standard view: (1) large op…
The survey of the COSMOS field by the VLT Survey Telescope is an appealing testing ground for variability studies of active galactic nuclei (AGN). With 54 r-band visits over 3.3 yr and a single-visit depth of 24.6 r-band mag, the dataset is also particularly interesting in the context of performance forecasting for the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). This work is the fifth in a series dedicated to the development of an automated, robust, and efficient methodology to identify optically variable AGN, aimed at deploying it on future LSST data. We test the perform…
In order to shed light on how galactic properties depend on the intergalactic medium (IGM) environment traced by the Ly$α$ forest, we observationally investigate the IGM-galaxy connection using the publicly available 3D IGM tomography data (CLAMATO) and several galaxy catalogs in the COSMOS field. We measure the cross-correlation function (CCF) for $570$ galaxies with spec-$z$ measurements and detect a correlation with the IGM up to $50$ $h^{-1}$ comoving Mpc. We show that galaxies with stellar masses of $10^9-10^{10}$ M$_\odot$ are the dominant contributor to the total CCF signal. We also inv…
Simulations of the formation of large-scale structure predict that dark matter, low density highly ionized gas, and galaxies form 10 40 Mpc scale filaments. These structure are easily recognized in the distribution of galaxies, but have not been directly observed in the distribution of the gas. We use Ly-alpha absorption lines in the spectra of 24 AGN to present a new way to probe these filaments. We use a new catalogue of nearby (cz<10,000 km/s) galaxies, complete down to a luminosity of about 0.05 L* for the region of space analyzed here. Using HST spectra of 24 AGN we sample the gas associa…
Blazars are some of the brightest UV and X-ray sources in the sky and are valuable probes of the elusive warm-hot intergalactic medium (WHIM; $T{\simeq} 10^5-10^7$ K). However, many of the brightest blazars$-$called BL Lac objects such as 1ES1553+113$-$have quasi-featureless spectra and poorly constrained redshifts. Here, we significantly improve the precision of indirect redshift constraints for blazars based on the edge of the $\rm{H\,I}$ Ly$α$ forest observed in their UV spectra. We develop a robust technique to constrain the redshift of a $z<0.5$ AGN or blazar with a $1σ$ uncertainty of ${…
The ionizing fluxes from quasars and other active galactic nuclei (AGN) are critical for interpreting their emission-line spectra and for photoionizing and heating the intergalactic medium (IGM). Using far-ultraviolet spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), we directly measure the rest-frame ionizing continua and emission lines for 159 AGN at redshifts 0.001 < z_AGN < 1.476 and construct a composite spectrum from 475-1875A. We identify the underlying AGN continuum and strong EUV emission lines from ions of oxygen, neon, and nitrogen after masking…
We present two catalogues of active galactic nucleus (AGN) candidates selected from the latest data of two all-sky surveys -- Data Release 2 (DR2) of the \emph{Gaia} mission and the unWISE catalogue of the \emph{Wide-field Infrared Survey Explorer} (\emph{WISE}). We train a random forest classifier to predict the probability of each source in the \emph{Gaia}-unWISE joint sample being an AGN, $P_{\rm RF}$, based on \emph{Gaia} astrometric and photometric measurements and unWISE photometry. The two catalogues, which we designate C75 and R85, are constructed by applying different $P_{\rm RF}$ thr…
Subaru/SuprimeCam narrowband photometry of the SSA22 field reveals the presence of four Lyman continuum (LyC) candidates among a sample of 14 AGN. Two show offsets and likely have stellar LyC in nature or are foreground contaminants. The remaining two LyC candidates are Type I AGN. We argue that the average LyC escape fraction of high redshift low luminosity AGN is not likely to be unity, as often assumed in the literature. From direct measurement we obtain the average LyC-to-UV flux density ratio and ionizing emissivity for a number of AGN classes and find it at least a factor of two lower th…
We use the Random Forest (RF) algorithm to develop a tool for automated activity classification of galaxies into 5 different classes: Star-forming (SF), AGN, LINER, Composite, and Passive. We train the algorithm on a combination of mid-IR (WISE) and optical photometric data while the true labels (activity classes) are based on emission line ratios. Our classifier is built to be redshift-agnostic and it is applicable to objects up to z $\sim$0.1. It reaches a completeness $>$80 % for SF and Passive galaxies, and $\sim$60 % for AGN. Applying it to an all-sky galaxy catalog (HECATE) reveals a lar…
We examine the column density distribution function (CDDF) and Doppler parameter distribution from hydrodynamical simulations and Cosmic Origins Spectrograph (COS) observations of the Lyman-alpha forest at redshift $0\leq z\leq 0.2$. Allowing for a factor of two uncertainty in the metagalactic HI photoionisation rate, our hydrodynamical simulations are in good agreement ($1$-$1.5σ$) with the shape and amplitude of the observed CDDF at HI column densities $10^{13.3}\rm\,cm^{-2}\leq N_{\rm HI}\leq 10^{14.5}\rm\,cm^{-2}$. However, the Doppler widths of the simulated lines remain too narrow with r…
The statistical distributions of active galactic nuclei (AGN), i.e. accreting supermassive black holes (BHs), in mass, space and time, are controlled by a series of key properties, namely the BH-galaxy scaling relations, Eddington ratio distributions and fraction of active BHs (duty cycle). Shedding light on these properties yields strong constraints on the AGN triggering mechanisms whilst providing a clear baseline to create useful mock catalogues for the planning of large galaxy surveys. We here delineate a robust methodology to create mock AGN catalogs built on top of large N-body dark matt…
We identify the intrinsic dependence of star formation quenching on a variety of galactic and environmental parameters, utilizing a machine learning approach with Random Forest classification. We have previously demonstrated the power of this technique to isolate causality, not mere correlation, in complex astronomical data. First, we analyze three cosmological hydrodynamical simulations (Eagle, Illustris, and IllustrisTNG), selecting snapshots spanning the bulk of cosmic history from comic noon ($z \sim 2$) to the present epoch, with stellar masses in the range $9 < \log(M_*/M_{\odot}) < 12$.…
We add a suite of chemical abundances to the MACER (Massive AGN Controlled Ellipticals Resolved) 2D code, by solving 12 additional continuity equations for H, He, C, N, O, Ne, Mg, Si, S, Ca, Fe and Ni respectively with sources from AGB stars and supernovae of type Ia and II with metal yields based on standard stellar physics. New stars, formed in Toomre unstable circumnuclear disks (of a size $\lesssim150$ parsec), are assumed to have a top-heavy initial mass function with a power index of 1.65. The metal dilution effects due to cosmic accretion are also included. With the high resolution of f…
The CAMELS project: Expanding the galaxy formation model space with new ASTRID and 28-parameter TNG and SIMBA suites
Harvard-Smithsonian Center for Astrophysics（哈佛-史密松天体物理中心）；Carnegie Mellon University（卡内基梅隆大学）；Flatiron Institute（弗莱提荣研究所）；Columbia University（哥伦比亚大学）；University of Connecticut（康涅狄格大学）；Princeton University（普林斯顿大学）；University of California, Riverside（加州大学河滨分校）
Lyman-Alpha Forest and its Cross-Correlation with High-Redshift Galaxies in Effective Field Theory at the Field Level
Center for Theoretical Physics – a Leinweber Institute, Massachusetts Institute of Technology（麻省理工学院理论物理中心）；The NSF AI Institute for Artificial Intelligence and Fundamental Interactions（美国国家科学基金会人工智能基础相互作用研究所）；Department of Physics, Columbia University（哥伦比亚大学物理系）；NASA Hubble Fellowship Program（NASA 哈勃奖学金计划）；Theory Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK)（高能加速器研究机构粒子与核研究学院理论中心）
We report a $z=2.30$ galaxy protocluster (COSTCO-I) in the COSMOS field, where the Lyman-$α$ forest as seen in the CLAMATO IGM tomography survey does not show significant absorption. This departs from the transmission-density relationship (often dubbed the fluctuating Gunn-Peterson approximation; FGPA) usually expected to hold at this epoch, which would lead one to predict strong Ly$α$ absorption at the overdensity. For comparison, we generate mock Lyman-$α$ forest maps by applying FGPA to constrained simulations of the COSMOS density field, and create mocks that incorporate the effects of fin…
We present a new method to study the contribution of faint sources to the UV background using the 1D correlation of metal absorbers with the intergalactic medium (IGM) transmission in a Quasi Stellar Object (QSO) sightline. We take advantage of a sample of $25$ high signal-to-noise ratio QSO spectra to retrieve $150$ triply-ionised carbon (\cfour) absorbers at $4.5\lesssim z\lesssim 6.2$, of which $37$ systems whose expected H{~\small I} absorption lie in the Lyman-$α$ forest. We derive improved constraints on the cosmic density of \cfour \,at $4.3< z < 6.2$ and infer from abundance-matching t…
We use bulge-type classifications of 809 representative SDSS galaxies by Gadotti (2009) to classify a large sample of galaxies into real bulges (classical or elliptical) and pseudobulges using Random Forest. We use structural and stellar population predictors that can easily be measured without image decomposition. Multiple parameters such as the central mass density with 1 kpc, concentration index, Sérsic index and velocity dispersion do result in accurate bulge classifications when combined together. We classify $\sim 44,500$ face-on galaxies above stellar mass of 10$^{10}$ M$_\odot$ and red…
AGN feedback is an important ingredient in galaxy evolution, however its treatment in numerical simulations is necessarily approximate, requiring subgrid prescriptions due to the dynamical range involved in the calculations. We present a suite of SPH simulations designed to showcase the importance of the choice of a particular subgrid prescription for AGN feedback. We concentrate on two approaches to treating wide-angle AGN outflows: thermal feedback, where thermal and kinetic energy is injected into the gas surrounding the SMBH particle, and virtual particle feedback, where energy is carried …
Active galactic nuclei (AGN) feedback has a major impact onto the supermassive black-hole (SMBH) growth, the properties of the host galaxies, and their cosmic evolution. We investigate the effects of different kinetic feedback prescriptions on the observable properties of AGN and their host galaxies at $z>6$ in a suite of zoom-in cosmological simulations. We find that kinetic feedback decreases the column density of the interstellar medium (ISM) in the host galaxy by up to a factor of $\approx10$, especially when the SMBHs reach high accretion rates ($\approx10-30\,\mathrm{M_\odot\,yr^{-1}}$).…
Active Galactic Nuclei are powered by geometrically-thin accretion disks surrounding a central supermassive black hole. Here we explore the evolution of stars embedded in these extreme astrophysical environments (AGN stars). Because AGN disks are much hotter and denser than the interstellar medium, AGN stars are subject to very different boundary conditions than normal stars. They are also strongly affected by both mass accretion, which can runaway given the vast mass of the disk, and mass loss due to super-Eddington winds. Moreover, chemical mixing plays a critical role in the evolution of th…
Similarly to the cosmic star formation history, the black hole accretion rate density of the Universe peaked at 1<z<3. This cosmic epoch is hence best suited for investigating the effects of radiative feedback from AGN. Observational efforts are underway to quantify the impact of AGN feedback, if any, on their host galaxies. Here we present a study of the molecular gas content of AGN hosts at z~1.5 using CO[2-1] line emission observed with ALMA for a sample of 10 AGNs. We compare this with a sample of galaxies without an AGN matched in redshift, stellar mass, and star formation rate. We detect…
