Halo Mass Research Articles

Stellar halos of bright central galaxies. A view from the FEGA semi-analytic model of galaxy formation and VEGAS survey

We present theoretical predictions and extrapolations from observed data of the stellar halos surrounding central group and cluster galaxies, and the transition radius between them and the intracluster or diffuse light. Leveraging the state-of-the-art semi-analytic model of galaxy formation FEGA (Formation and Evolution of GAlaxies), applied to two dark matter-only cosmological simulations, we derived both the stellar halo mass and its radius. Using theoretical assumptions about the diffuse light distribution and halo concentration, we extrapolated the same information for observed data from the VEGAS survey. Our model, supported by observational data and independent simulation results, predicts an increasing transition radius with halo mass, a constant stellar halo-to-intracluster light ratio, and a stable stellar halo mass fraction with increasing halo mass. Specifically, we find that the transition radius between the stellar halo and the diffuse light ranges from 20 to 250 kpc, from Milky Way-like halos to large clusters, while the stellar halo mass comprises only a small fraction, between 7<!PCT!> and 18<!PCT!>, of the total stellar mass within the virial radius. These results support the idea that the stellar halo can be viewed as a transition region between the stars bound to a galaxy and those belonging to the intracluster light and are consistent with recent observations and theoretical predictions.

Mining for Protoclusters at z ∼ 4 from Photometric Data Sets with Deep Learning

Protoclusters are high-z overdense regions that will evolve into clusters of galaxies by z = 0, making them ideal for studying galaxy evolution expected to be accelerated by environmental effects. However, it has been challenging to identify protoclusters beyond z = 3 only by photometry due to large redshift uncertainties hindering statistical study. To tackle the issue, we develop a new deep-learning-based protocluster detection model, PCFNet, which considers a protocluster as a point cloud. To detect protoclusters at z ∼ 4 using only optical broadband photometry, we train and evaluate PCFNet with mock g-dropout galaxies based on the N-body simulation with the semianalytic model. We use the sky distribution, i-band magnitude, (g − i) color, and the redshift probability density function surrounding a target galaxy on the sky. PCFNet detects 5 times more protocluster member candidates while maintaining high purity (recall = 7.5% ± 0.2%, precision = 44% ± 1%) than conventional methods. Moreover, PCFNet is able to detect more progenitors ( Mhaloz=0=1014−14.5M⊙ ) that are less massive than supermassive clusters like the Coma cluster. We apply PCFNet to the observational photometric data set of the Hyper Suprime-Cam Strategic Survey Program Deep/UltraDeep layer (∼17 deg2) and detect 121 protocluster candidates at z ∼ 4. We find that the rest-UV luminosities of our protocluster member candidates are brighter than those of field galaxies, which is consistent with previous studies. Additionally, the quenching of satellite galaxies depends on both the core galaxy’s halo mass at z ∼ 4 and accumulated mass until z = 0 in the simulation. PCFNet is very flexible and can find protoclusters at other redshifts or in future extensive surveys by Euclid, Legacy Survey of Space and Time, and Roman.

The VANDELS Survey: Star formation and quenching in two over-densities at 3 < z < 4

Context. Exploring galaxy evolution in dense environments, such as proto-clusters, is pivotal for understanding the mechanisms that drive star formation and the quenching of star formation. Aims. This study provides insights into how two over-densities could have impacted the physical properties, such as the star formation rate, stellar mass, morphology, and the evolution of their members, particularly members characterised by a quenching of star formation. Methods. We focus on the over-densities identified at 3 < z < 4 in the Chandra Deep Field South (CDFS) and in the Ultra Deep Survey (UDS) regions of the VIMOS (VIsible MultiObject Spectrograph) Ultra Deep Survey (VANDELS). Our methodology involves the analysis of the spectral energy distribution of the members of the over-densities and of the galaxies in the field. We relied on Bayesian analysis techniques BEAGLE and BAGPIPES to study the best-fit physical parameters and the rest-frame U − V and V − J colours (UVJ). This approach allowed us to separate quenched and star-forming galaxies based on the UVJ diagram and by estimating their specific star formation rate (sSFR). We used the TNG300 simulation to interpret our results. Results. We find that two out of 13 over-densities host quenched galaxies, with red rest-frame U − V colour and low sSFR. The physical properties of them are consistent with those of massive passive galaxies from the literature. The quenched members are redder, older, more massive, and show a more compact morphology than the other galaxy members. The two over-densities, with the highest-density peaks at z ≃ 3.55 and z ≃ 3.43, respectively, have dark matter halo masses consistent with being proto-clusters at z ∼ 3 and they each host an active galactic nucleus (AGN). We found five AGNs in the structure at z ≃ 3.55 and three AGNs in the one at z ≃ 3.43. In comparison to quenched galaxies in the field, our massive quenched members show a higher local density environment. By using the IllustrisTNG simulation (TNG300), we find that proto-cluster structures with quenched galaxies at high redshift are likely to evolve into a structure with a higher fraction of passive galaxies by z = 1. Conclusions. The two over-densities studied here host massive quenched galaxies in their highest-density peaks and AGNs. By following the evolution of the passive galaxies in the simulated proto-clusters at z = 3 from the TNG300 simulation, we find that the median of their sSFRs was larger than 10−8 yr−1 at z = 6 and the median mass growth rate was 96% from z = 6 to z = 3. In 20% of the simulated proto-clusters, the passive galaxy had already accreted 10–20% of the mass at z = 6, with SFRs > 100 M⊙ yr−1 at z = 8. The conditions for this favorable mass assembly could be the galaxy interactions and the high gas accretion rate in the dense environment. As a consequence, the quenching of the star formation at z = 3 could be driven by the black hole mass growth and AGN feedback. This scenario is consistent with the properties of the two quenched galaxies we find in our two over-densities at z ∼ 3.

Observational Signatures of AGN Feedback in the Morphology and the Ionization States of Milky Way-like Galaxies

We make an in-depth analysis of different active galactic nuclei (AGN) jet models’ signatures, inducing quiescence in galaxies with a halo mass of 1012 M ⊙. Three jet models, including cosmic-ray-dominant, hot thermal, and precessing kinetic jets, are studied at two energy flux levels each, compared to a jet-free, stellar feedback-only simulation. Each of our simulations is idealized isolated galaxy simulations with AGN jet powers that are constant in time and generated using GIZMO and with FIRE stellar feedback. We examine the distribution of Mg ii, O vi, and O viii ions, alongside gas temperature and density profiles. Low-energy ions, like Mg ii, concentrate in the interstellar medium (ISM), while higher energy ions, e.g., O viii, prevail at the AGN jet cocoon’s edge. High-energy flux jets display an isotropic ion distribution with lower overall density. High-energy thermal or cosmic-ray jets pressurize at smaller radii, significantly suppressing core density. The cosmic-ray jet provides extra pressure support, extending cool and warm gas distribution. A break in the ion-to-mass ratio slope in O vi and O viii is demonstrated in the ISM-to-circumgalactic medium (CGM) transition (between 10 and 30 kpc), growing smoothly toward the CGM at greater distances.

The evolution of low-mass central galaxies in the vicinity of massive structures and its impact on the two-halo conformity

We investigated the population of low-mass central galaxies with M$_ star $ $h^ $ M$_ odot $, inhabiting regions near massive groups and clusters of galaxies using the IllustrisTNG300 and MDPL2-SAG simulations. We set out to study their evolutionary histories, aiming to find hints about the large-scale conformity signal they produce. We also used a control sample of central galaxies with the same stellar mass range located far away from massive structures. For both samples, we find a subpopulation of galaxies accreted by another halo in the past, but now considered central galaxies; we refer to these objects as former satellites. The number of former satellites is higher for quenched central galaxies near massive systems, with fractions of 45<!PCT!> and 17<!PCT!> in IllustrisTNG300 and MDPL2-SAG, respectively. The differences in the numerical resolution of each simulation lead to the different fractions of former satellites. Our results in TNG300 show that former satellites ``pollute'' the sample of central galaxies because they suffered environmental processes when they were satellites hosted typically by massive dark matter halos (M$_ $ $h^ $ M$_ odot $) since $z 0.5$. After removing former satellites, the evolutionary trends for quenched central galaxies near massive structures are fairly similar to those of the quenched control galaxies, showing small differences at low redshift. For MDPL2-SAG instead, former satellites were hosted by less massive halos, with a mean halo mass around $ $h^ $ M$_ odot $, and the evolutionary trends remain equal before and after removing former satellite galaxies. We also measured the two-halo conformity, that is, the correlation in the specific star formation rate between low-mass central galaxies and their neighbors at megaparsec scales, and how former satellites contribute to the signal at three different redshifts: $z=0, 0.3,$ and 1. The time evolution of the conformity signal in the simulations presents apparent contradictory results: it decreases from $z=0$ to $z=1$ in MDPL2-SAG, while it increases in TNG300. However, after removing former satellites in the latter, the signal is strongly reduced, but practically does not change at $z 0.3$, and it disappears at $z=1$. We compare our findings with recent literature data and discuss the conformity measurements, as different approaches can lead to varying results.

Examining the brightness variability, accretion disk, and evolutionary stage of the binary OGLE-LMC-ECL-14413

Several intermediate-mass close binary systems exhibit photometric cycles longer than their orbital periods, potentially due to changes in their accretion disks. Past studies indicate that analyzing historical light curves can provide valuable insights into disk evolution and track variations in mass transfer rates within these systems. Our study aims to elucidate both short-term and long-term variations in the light curve of the eclipsing system with a particular focus on the unusual reversals in eclipse depth. We aim to clarify the role of the accretion disk in these fluctuations, especially in long-cycle changes spanning hundreds of days. Additionally, we seek to determine the evolutionary stage of the system and gain insights into the internal structure of its stellar components. We analyzed photometric time series from the Optical Gravitational Lensing Experiment (OGLE) project in the $I$ and $V$ bands, and from the MAssive Compact Halo Objects (MACHO) project in the $B_ M $ and $R_ M $ bands, covering a period of 30.85 years. Using light curve data from 27 epochs, we constructed models of the accretion disk. An optimized simplex algorithm was employed to solve the inverse problem, deriving the best-fit parameters for the stars, orbit, and disk. We also utilized the Modules for Experiments in Stellar Astrophysics ( MESA ) software to assess the evolutionary stage of the binary system, investigating the progenitors and potential future developments. We found an orbital period of 38.15917 pm 0.00054 days and a long-term cycle of approximately 780 days. Temperature, mass, radius, and surface gravity values were determined for both stars. The photometric orbital cycle and the long-term cycle are consistent with a disk containing variable physical properties, including two shock regions. The disk encircles the more massive star and the system brightness variations align with the long-term cycle at orbital phase 0.25. Our mass transfer rate calculations correspond to these brightness changes. MESA simulations indicate weak magnetic fields in the donor star's subsurface, which are insufficient to influence mass transfer rates significantly.

A comparison of pre-existing ΛCDM predictions with the abundance of JWST galaxies at high redshift

Abstract Observations with the James Webb Space Telescope have revealed a high abundance of bright galaxies at redshift, z ≳ 12, which has been widely interpreted as conflicting with the ΛCDM model. In Cowley et al. (2018) predictions were made – prior to the JWST observations – for the expected abundance of these galaxies using the Durham semi-analytic galaxy formation model, galform, which is known to produce a realistic population of galaxies at lower redshifts including the present day. Key to this model is the assumption of a “top-heavy” initial mass function of stars formed in bursts (required to explain the number counts and redshift distribution of sub-millimetre galaxies). Here, we compare the rest-frame ultraviolet luminosity functions derived from JWST observations with those predicted by the Cowley et al. model up to z = 14 and make further predictions for z = 16. We find that below z ∼ 10, the Cowley et al. predictions agree very well with observations, while agreement at z ≳ 12 requires extending the model to take into account the timescale for the growth of obscuring dust grains at these very early times and its dependence on gas metallicity. We trace the evolution of these galaxies from z = 14 to z = 0 and find that their descendants typically reside in halos with a median mass 2.5 × 1013 h−1 M⊙. The stellar masses of the descendants range from 3.2 × 106 h−1 M⊙ to 3.2 × 1011 h−1 M⊙. Although these galaxies were all central galaxies at z = 14, over half of their descendants end up as satellites in massive halos.

Elevated UV luminosity density at Cosmic Dawn explained by non-evolving, weakly mass-dependent star formation efficiency

Abstract Recent observations with the James Webb Space Telescope (JWST) have uncovered unexpectedly high cosmic star formation activity in the early Universe, mere hundreds of millions of years after the Big Bang. These observations are often understood to reflect an evolutionary shift in star formation efficiency (SFE) caused by changing galactic conditions during these early epochs. We present FIREboxHR, a high-resolution, cosmological hydrodynamical simulation from the Feedback in Realistic Environments project, which offers insights into the SFE of galaxies during the first billion years of cosmic time. FIREboxHR re-simulates the cosmic volume (L = 22.1 cMpc) of the original FIREbox run with eight times higher mass resolution (mb ∼ 7800 M⊙), but with identical physics, down to z ∼ 6. FIREboxHR predicts ultraviolet (UV) luminosity functions in good agreement with available observational data. The simulation also successfully reproduces the observed cosmic UV luminosity density at z ∼ 6 − 14, demonstrating that relatively high star formation activity in the early Universe is a natural outcome of the baryonic processes encoded in the FIRE-2 model. According to FIREboxHR, the SFE – halo mass relation for intermediate mass halos (Mhalo ∼ 109 − 1011 M⊙) does not significantly evolve with redshift and is only weakly mass-dependent. These properties of the SFE – halo mass relation lead to a larger contribution from lower mass halos at higher z, driving the gradual evolution of the observed cosmic UV luminosity density. A theoretical model based on the SFE – halo mass relation inferred from FIREboxHR allows us to explore implications for galaxy evolution. Future observations of UV faint galaxies at z > 12 will provide an opportunity to further test these predictions and deepen our understanding of star formation during Cosmic Dawn.

How Do the Velocity Anisotropies of Halo Stars, Dark Matter, and Satellite Galaxies Depend on Host Halo Properties?

We investigate the mass (M 200) and concentration (c 200) dependencies of the velocity anisotropy (β) profiles for different components in the dark matter halo—including halo stars, dark matter, and subhalos—using systems from the IllustrisTNG simulations. Beyond a critical radius, β becomes more radial with the increase of M 200, reflecting more prominent radial accretion around massive halos. The critical radius is r ∼ r s , 0.3 r s , and r s for halo stars, dark matter, and subhalos, with r s being the scale radius of the host halos. This dependence on M 200 is the strongest for subhalos and the weakest for halo stars. In central regions, the β of halo stars and dark matter particles get more isotropic with the increase of M 200 in TNG300 due to baryons. By contrast, the β of dark matter from the dark-matter-only TNG300-Dark run shows much weaker dependence on M 200 within r s . Dark matter in TNG300 is slightly more isotropic than in TNG300-Dark at 0.2 r s < r < 10 r s and log10M200/M⊙<13.8 . Halo stars and dark matter also become more radial with the increase in c 200, at fixed M 200. Halo stars are more radial than the β profile of dark matter by approximately a constant beyond r s . Dark matter particles are more radial than subhalos. The differences can be understood, as subhalos on more radial orbits are more easily stripped, contributing more stars and dark matter to the diffuse components. We provide the fitting formula for the differences between the β of halo stars and dark matter at r s < r < 3 r s as βstar−βDM=(−0.034±0.012)log10M200/M⊙+(0.772±0.163) for log10M200/M⊙≥13 and as β star − β DM = 0.328 for log10M200/M⊙<13 .

The Massive and Distant Clusters of WISE Survey 2: Second Data Release

We present the second data release of the Massive and Distant Clusters of WISE Survey 2 (MaDCoWS2). We expand from the equatorial first data release to most of the Dark Energy Camera Legacy Survey area, covering a total area of 6498 deg2. The catalog consists of 133,036 signal-to-noise ratio (S/N) ≥ 5 galaxy cluster candidates at 0.1 ≤ z ≤ 2, including 6790 candidates at z > 1.5. We train a convolutional neural network (CNN) to identify spurious detections and include CNN-based cluster probabilities in the final catalog. We also compare the MaDCoWS2 sample with literature catalogs in the same area. The larger sample provides robust results that are consistent with our first data release. At S/N ≥ 5, we rediscover 59%–91% of clusters in existing catalogs that lie in the unmasked area of MC2. The median positional offsets are under 250 kpc, and the standard deviation of the redshifts is 0.031(1 + z). We fit a redshift-dependent power law to the relation between MaDCoWS2 S/N and observables from existing catalogs. Over the redshift ranges where the surveys overlap with MaDCoWS2, the lowest scatter is found between S/N and observables from optical/infrared surveys. We also assess the performance of our method using a mock light cone measuring purity and completeness as a function of cluster mass. The purity is above 90%, and we estimate the 50% completeness threshold at a virial mass of log(M/M ⊙) ≈ 14.3. The completeness estimate is uncertain due to the small number of massive halos in the light cone, but consistent with the recovery fraction found by comparing to other cluster catalogs.

Constraining the Low-mass End of the Stellar-to-halo Mass Relation with Surveys of Satellite Galaxies

The abundance of satellite galaxies is set by the hierarchical assembly of their host halo. We leverage this to investigate the low-mass end (M H < 1011 M ⊙) of the stellar-to-halo mass relation (SHMR), which is key to constraining theories of galaxy formation and cosmology. We argue that recent analyses of satellite galaxies in the Local Group environment have not adequately modeled the dominant source of scatter in satellite stellar mass functions: the variance in accretion histories for a fixed host halo mass. We present a novel inference framework that not only properly accounts for this halo-to-halo variance but also naturally identifies the amount of host halo mass mixing, which is generally unknown. Specifically, we use the semianalytical SatGen model to construct mock satellite galaxy populations consistent with the third data release of the Satellites Around Galactic Analogs survey. We demonstrate that even under the most idealized circumstances, the halo-to-halo variance makes it virtually impossible to put any meaningful constraints on the scatter in the SHMR. Even a satellite galaxy survey made up 100 hosts can at best only place an upper limit of ∼0.5 dex on the scatter (at the 95% confidence level). This is because the large variance in halo assembly histories dominates over the scatter in the SHMR. This problem can be overcome by increasing the sample size of the survey by an order of magnitude (∼1000 host galaxies), something that should be fairly straightforward with forthcoming spectroscopic surveys.

Test of Cosmic Web-feeding Model for Star Formation in Galaxy Clusters in the COSMOS Field

It is yet to be understood how large-scale environments influence star formation activity in galaxy clusters. One recently proposed mechanism is that galaxy clusters can remain star forming when fed by infalling groups and star-forming galaxies from large-scale structures (LSSs) surrounding them (the “web-feeding” model). Using the COSMOS2020 catalog that has half a million galaxies with high-accuracy (σ Δz/1+z ∼ 0.01) photometric redshifts, we study the relationship between star formation activities in galaxy clusters and their surrounding environment to test the web-feeding model. We first identify 68 cluster candidates at 0.3 ≤ z ≤ 1.4 with halo masses at 1013.0–1014.5 M ⊙ and the surrounding LSSs with the friends-of-friends algorithm. We find that clusters with low fractions of quiescent galaxies tend to be connected with extended LSSs as expected in the web-feeding model. We also investigated the time evolution of the web-feeding trend using the IllustrisTNG cosmological simulation. Even though no clear correlation between the quiescent galaxy fraction of galaxy clusters and the significance of LSSs around them is found in the simulation, we verify that the quiescent galaxy fractions of infallers such as groups (M 200 ≥ 1012 M ⊙) and galaxies (M 200 < 1012 M ⊙) are smaller than the quiescent fraction of cluster members and that infallers can lower the quiescent fraction of clusters. These results imply that cluster-to-cluster variations of quiescent galaxy fraction at z ≤ 1 can at least partially be explained by feeding materials through cosmic webs to clusters.

Equilibrium States of Galactic Atmospheres. II. Interpretation and Implications

The scaling of galaxy properties with halo mass suggests that feedback loops regulate star formation, but there is no consensus yet about how those feedback loops work. To help clarify discussions of galaxy-scale feedback, Paper I presented a very simple model for supernova feedback that it called the minimalist regulator model. This follow-up paper interprets that model and discusses its implications. The model itself is an accounting system that tracks all of the mass and energy associated with a halo’s circumgalactic baryons—the central galaxy’s atmosphere. Algebraic solutions for the equilibrium states of that model reveal that star formation in low-mass halos self-regulates primarily by expanding the atmospheres of those halos, ultimately resulting in stellar masses that are insensitive to the mass-loading properties of galactic winds. What matters most is the proportion of supernova energy that couples with circumgalactic gas. However, supernova feedback alone fails to expand galactic atmospheres in higher-mass halos. According to the minimalist regulator model, an atmospheric contraction crisis ensues, which may be what triggers strong black hole feedback. The model also predicts that circumgalactic medium properties emerging from cosmological simulations should depend largely on the specific energy of the outflows they produce, and we interpret the qualitative properties of several numerical simulations in light of that prediction.

The importance of stochasticity in determining galaxy emissivities and UV LFs during cosmic dawn and reionization

The stochastic nature of star formation and photon propagation in high-redshift galaxies can result in sizable galaxy-to-galaxy scatter in their properties. Ignoring this scatter by assuming mean quantities can bias estimates of their emissivity and corresponding observables. We constructed a flexible, semi-empirical model, sampling scatter around the following mean relations: (i) the conditional halo mass function (CHMF); (ii) the stellar-to-halo mass relation (SHMR); (iii) the galaxy star formation main sequence (SFMS); (iv) the fundamental metallicity relation (FMR); (v) the conditional intrinsic luminosity; and (vi) the photon escape fraction. In our fiducial model, ignoring scatter in these galaxy properties overestimates the duration of the Epoch of Reionization (EoR), delaying its completion by $ z 1--2. We quantified the relative importance of each of the above sources of scatter in determining the ionizing, soft-band X-ray, and Lyman Werner (LW) emissivities as a function of scale and redshift. We find that scatter around the SFMS is important for all bands, especially at the highest redshifts where the emissivity is dominated by the faintest, most "bursty" galaxies. Ignoring this scatter would underestimate the mean emissivity and its standard deviation computed over 5 cMpc regions by factors of up to sim 2--10 at $5 z 15$. The scatter around the X-ray luminosity to star formation rate and metallicity relation is important for determining X-ray emissivity, accounting for roughly half of its mean and standard deviation. The importance of scatter in the ionizing escape fraction depends on its functional form, while scatter around the SHMR contributes at the level of sim 10--20&lt;!PCT!&gt;. Other sources of scatter have a negligible contribution to the emissivities. Although scatter does flatten the UV luminosity functions, shifting the bright end by 1--2 magnitudes, the level of scatter in our fiducial model is insufficient to fully explain recent estimates from JWST photometry (consistent with previous studies). We conclude that models of the EoR should account for the burstiness of star formation, while models for the cosmic 21cm signal should additionally account for scatter in intrinsic X-ray production.

High-resolution HI mapping of nearby extremely metal-poor blue compact dwarf galaxies

Optical observations of blue compact dwarf galaxies (BCDs) show they typically have high specific star formation rates black (sSFRs) and low metallicites. A subset of these galaxies (those with the lowest gas phase metallicities) display cometary optical morphologies similar to those found at high redshift. Whether this combination of properties predominantly arises from interactions with neighbours or via accretion from the cosmic web, or is indeed due to something else, remains unclear. Our aim is to use high-resolution mapping to gain insights into the processes driving the observed properties of a sample of extremely metal-poor (XMP) BCDs. We present Very Large Array B-- and C--configuration mapping of the four BCDs of our sample. For three of the targeted BCDs, we also detected and mapped the in their nearby companions. In these three cases, there is morphological and kinematic evidence of a recent flyby interaction between the BCD and a nearby companion galaxy. The evidence for recent interactions for these three BCDs is corroborated by our analysis of the tidal forces exerted on the BCDs by companions with available spectroscopic redshifts. In one of these cases, J0204--1009, we obtain sufficient spatial resolution to determine that the BCD is dominated by dark matter black (DM) and estimate its DM halo mass to be in the range of 1.2 times 1011 to 5.2 times 1011 However, it is the most isolated BCD in our small sample, J0301--0052, that shows one of the most asymmetric morphologies . J0301--0052 has a similar cometary morphology to its optical morphology, although the column density maximum is projected at the end of the optical tail. Our observations suggest that J0301--0052 may be undergoing a merger, while the other members of our BCD sample show evidence of a recent tidal interaction with a near neighbour. While our selection criteria favour BCDs with companions, our results are consistent with previous literature showing that most BCDs are associated with either mild tidal interactions or mergers.

The baryon census and the mass-density of stars, neutral gas, and hot gas as a function of halo mass

Abstract We study the stellar, neutral gas content within halos over a halo mass range 1010to1015.5M⊙ and hot X-ray gas content over a halo mass range 1012.8to1015.5M⊙ in the local universe. We combine various empirical datasets of stellar, H i and X-ray observations of galaxies, groups and clusters to establish fundamental baryonic mass vs halo mass scaling relations. These scaling relations are combined with halo mass function to obtain the baryon densities of stars, neutral gas and hot gas (T &amp;gt; 106K), as a function of halo mass. We calculate the contributions of the individual baryonic components to the cosmic baryon fraction. Cosmic stellar mass density ($\Omega _\text{star}=2.09^{+0.21}_{-0.18} \times 10^{-3}$), cosmic H i mass density ($\Omega _\rm{H\,{\small I}}=0.49^{+0.25}_{-0.12} \times 10^{-3}$) and cosmic neutral gas mass density ($\Omega _\text{neutral gas}=0.71^{+0.39}_{-0.18} \times 10^{-3}$) estimates are consistent with previous more direct method measurements of these values, thereby establishing the veracity of our method. We also give an estimate of the cosmic hot plasma density ($\Omega _\text{hot gas}=2.58^{+2.1}_{-0.66} \times 10^{-3}$).

The VST ATLAS Quasar Survey – III. Halo mass function via quasar clustering and quasar-CMB lensing cross-clustering

ABSTRACT We exploit the VST ATLAS quasar (QSO) catalogue to perform three measurements of the quasar halo mass profile. First, we make a new estimate of the angular autocorrelation function of ≈230 000 ATLAS quasars with $z_{\rm photo}\lesssim 2.5$ and $17 &amp;lt; g &amp;lt; 22$. By comparing with the $\Lambda$CDM mass clustering correlation function, we measure the quasar bias to be $b_{\rm Q}\approx 2.1$, implying a quasar halo mass of $M_{\rm halo} \approx 8.5\times 10^{11}\,h^{-1}\,{\rm M}_\odot$. Second, we cross-correlate these $z\approx 1.7$ ATLAS quasars with the Planck cosmic microwave background (CMB) lensing maps, detecting a somewhat stronger signal at $4\,{\rm arcmin} &amp;lt; \theta &amp;lt; 60\,{\rm arcmin}$ than previous authors. Scaling these authors’ model fit to our data, we estimate a quasar host halo mass of $M_{\rm halo}\approx 8.3\times 10^{11}\,h^{-1}\,{\rm M}_\odot$. Third, we fit halo occupation sistribution (HOD) model parameters to our quasar autocorrelation function and from the derived halo mass function, we estimate a quasar halo mass of $M_{\rm halo}\approx 2.5\times 10^{12}\,h^{-1}\,{\rm M}_\odot$. We then compare our HOD model prediction to our quasar-CMB lensing result, confirming their consistency. We find that most (≈2/3) QSOs have halo masses within a factor of ≈3 of this average mass. An analysis based on the probability of X-ray detections of AGN in galaxies and the galaxy stellar mass function gives a similarly small mass range. Finally, we compare the quasar halo mass and luminosity functions and suggest that gravitational growth may produce the constant space density with redshift seen in the quasar luminosity function.

JWST lensed quasar dark matter survey – II. Strongest gravitational lensing limit on the dark matter free streaming length to date

ABSTRACT This is the second in a series of papers in which we use JWST Mid Infrared Instrument multiband imaging to measure the warm dust emission in a sample of 31 multiply imaged quasars, to be used as a probe of the particle nature of dark matter. We present measurements of the relative magnifications of the strongly lensed warm dust emission in a sample of nine systems. The warm dust region is compact and sensitive to perturbations by populations of haloes down to masses $\sim 10^6$ M$_{\odot }$. Using these warm dust flux-ratio measurements in combination with five previous narrow-line flux-ratio measurements, we constrain the halo mass function. In our model, we allow for complex deflector macromodels with flexible third- and fourth-order multipole deviations from ellipticity, and we introduce an improved model of the tidal evolution of subhaloes. We constrain a WDM model and find an upper limit on the half-mode mass of $10^{7.6}\, {\rm M}_\odot$ at posterior odds of 10:1. This corresponds to a lower limit on a thermally produced dark matter particle mass of 6.1 keV. This is the strongest gravitational lensing constraint to date, and comparable to those from independent probes such as the Ly $\alpha$ forest and Milky Way satellite galaxies.

The VST ATLAS Quasar Survey – II. Halo mass profiles of galaxies, LRGs and galaxy clusters via quasar and CMB lensing

ABSTRACT We cross-correlate a low-contamination subset of the VST ATLAS $g\lt 22.5$ quasar catalogue with $g\lt 21.5$ galaxy clusters, $r\lt 21$ galaxies and $r\lt 19.5$ luminous red galaxies (LRGs) to probe their halo mass profiles via quasar magnification bias caused by weak lensing. In the case of galaxy clusters, we find that at small scales their mass profiles are well fitted by Navarro, Frenk, and White models with masses within the expected range. For the galaxies, we find consistency with previous Sloan Digital Sky Survey-based results for the galaxy–quasar cross-correlation and the galaxy auto-correlation functions. Disagreement as to whether the cross-correlation results are in tension with $\Lambda$cold dark matter appears due to different assumptions as to whether galaxies trace mass. We conclude that halo occupation distribution (HOD) models fit the galaxy–quasar lensing results better than models where galaxies trace the mass. We further test the cluster and galaxy HOD models in the 2-halo range using the Planck cosmic microwave background (CMB) lensing map, finding that the cross-correlation with both the poorest clusters and the galaxies may be marginally overpredicted by the above HOD models. Finally, we measure the magnification bias of LRGs using both quasar and CMB lensing and find that the observed quasar lensing amplitude may be ${\approx} 2\times$ too high and, on larger scales, the CMB lensing amplitude may be too low to be explained by a standard LRG HOD model.

Why Do Semianalytic Models Predict Higher Scatter in the Stellar Mass–Halo Mass Relation Than Cosmological Hydrodynamic Simulations?

Semianalytic models (SAMs) systematically predict higher-stellar mass scatter at a given halo mass than hydrodynamical simulations and most empirical models. Our goal is to investigate the physical origin of this scatter by exploring modifications to the physics in the SAM Dark Sage. We design two black hole formation models that approximate results from the IllustrisTNG 300-1 hydrodynamical simulation. In the first model, we assign a fixed black hole mass of 106 M ⊙ to every halo that reaches 1010.5 M ⊙. In the second model, we disregard any black hole growth as implemented in the standard Dark Sage model. Instead, we force all black hole masses to follow the median z = 0 black hole mass–halo mass relation in IllustrisTNG 300-1 with an imposed fixed scatter. We find that each model on its own does not significantly reduce the scatter in stellar mass. To explore the effects of active galactic nucleus (AGN) feedback in addition to black hole seeding, we replace the native Dark Sage AGN feedback model with a simple model where we turn off cooling for galaxies with black hole masses above 108 M ⊙. With the additional modification in AGN feedback, we find that the supermassive black hole seeding and fixed conditional distribution models create a significant reduction in the scatter in stellar mass at halo masses between 1011–14 M ⊙. These results suggest that AGN feedback in SAMs acts in a qualitatively different way than feedback implemented in cosmological simulations. Either or both may require substantial modification to match the empirically inferred scatter in the stellar mass–halo mass relation.