arXiv subjects

Jesse B. Golden-Marx

Publications and source records attributed to Jesse B. Golden-Marx.

15 recordsLinked to original sources

arXiv2026

A Splashback-like Feature of Central Galaxies in Galaxy Clusters

We investigate a splashback-like feature in the outer region of central galaxies (CGs) in clusters. This feature is detected as a "dip" in the radial slope of the CG surface brightness, derived through the stacking of Dark Energy Survey data of over 4000 galaxy clusters in the redshift range of 0.2 to 0.5 with richness 20 and above. The local minimum of the dip occurs between 40 to 60 kpc from the CG center, with a mild dependence on cluster richness. This feature resembles the density transition caused by the splashback effect at the outskirts of galaxy clusters, when accreted matter reaches the apocenter for the first time. We turn to the IllustrisTNG hydro-dynamic simulation to gain theoretical insights. Density bumps, shells and accretion streaks are identified in the diffuse stellar content of the CGs and intra-cluster light which relate to the recent history of disruption and accretion. These features occur at the outskirts of the CGs, up to several hundred kiloparsecs from the cluster center. Thus, the location of the splashback-like dip in the data potentially marks the edge of the CG and the beginning of a region with the cluster diffuse light undergoing active or recent accretion.

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arXiv2026

Imprints of Mass Accretion History on Galaxy Cluster Morphology

Variations in dynamical states of galaxy clusters can introduce biases and scatter in observable-mass relations. The dynamical state of a cluster is an emergent feature of its mass accretion history (MAH), it is therefore useful to constrain the MAH of the cluster. In this work, we characterize 305 massive clusters from The300 project by connecting features from their projected stellar distributions to their mass accretion histories (MAH). As a baseline, we first correlate host dark matter halo dynamical state indicators at $z=0$ with their MAH via the Spearman rank correlation coefficient $ρ_{\mathrm{sp}}$. Both substructure mass fraction and center-of-mass offset measurements correlate strongly with the MAH measured between $0.1\lesssim z\lesssim 1$. We repeat this exercise with morphological measurements of projected stellar density maps, many of which exhibit moderate correlation strength with different times in the MAH. Broadly, core morphological measurements ($r \leq 30\,\mathrm{kpc}$) correlate better with early-time MAH. Core-excised ($50\,\mathrm{kpc} \leq r \leq 1\,\mathrm{Mpc}$) morphological measurements correlate better with late-time MAH. We further quantify the MAH prediction power of both traditional dynamical state indicators and morphological parameters using Multivariable Conditional Abundance Matching (MultiCAM). MultiCAM employs simple rank-ordering operations, making it straightforward to translate to observed datasets. We find reasonable ($ρ_{\mathrm{sp}} \geq 0.6$) performance for predictions of the mass fraction between $1\lesssim z\lesssim 0.1$, though with notable information loss when using projected quantities. In one example application of our methodology, we use the coefficients of the MultiCAM models to select subsamples of galaxy clusters that have accreted more (or less) of their $z = 0$ mass budget over a given time frame.

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arXiv2025

Predicting Halo Formation Time Using Machine Learning

Context:Halo formation time, which quantifies the mass assembly history of dark-matter halos, directly impacts galaxy properties and evolution. Although not directly observable, it can be inferred through proxies like star formation history or galaxy spatial distributions. Recent advances in machine learning enable more accurate predictions of halo formation time using galaxy and halo properties. Aims:This study aims to investigate a machine learning-based approach to predict halo formation time-defined as the epoch when a halo accretes half of its current mass-using both halo and baryonic properties derived from cosmological simulations. By incorporating properties associated with the brightest cluster galaxy located at the cluster center, its associated intracluster light component and satellite galaxies, we aim to surpass these analytical predictions, improve prediction accuracy and identify key properties that can provide the best proxy for the halo assembly history. Methods:Using The Three Hundred cosmological simulations, we train Random Forest (RF) and Convolutional Neural Network (CNN) models on halo and baryonic properties, such as mass, concentration, stellar and gas masses, and features of the brightest cluster galaxy and intracluster light. CNN models are trained on two-dimensional radial property maps. We also construct simple linear models using only observationally accessible features. Results:RF models show median biases of 4%-9% with standard deviations of 20%. CNN models reduce median bias to <4%, although they have higher scatter. Simple linear models using a limited number of observables achieve prediction accuracy comparable to RF models. Traditional relations between halo formation time and mass/concentration are preserved.

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arXiv2025

Intra-Cluster Light as a Dynamical Clock for Galaxy Clusters: Insights from the MAGNETICUM, IllustrisTNG, Hydrangea and Horizon-AGN Simulations

As the most massive nodes of the cosmic web, galaxy clusters represent the best probes of structure formation. Over time, they grow by accreting and disrupting satellite galaxies, adding those stars to the brightest cluster galaxy (BCG) and the intra-cluster light (ICL). However, the formation pathways of different galaxy clusters can vary significantly. To inform upcoming large surveys, we aim to identify observables that can distinguish galaxy cluster formation pathways. Using four different hydrodynamical simulations, Magneticum, TNG100 of IllustrisTNG, Horizon-AGN, and Hydrangea, we study how the fraction of stellar mass in the BCG and ICL ($f_{ICL+BCG}$) relates to the galaxy cluster mass assembly history. For all simulations, $f_{ICL+BCG}$ is the best tracer for the time at which the cluster has accumulated 50% of its mass ($z_{f}$), performing better than other typical dynamical tracers, such as the subhalo mass fraction, the halo mass, and the center shift. More relaxed clusters have higher $f_{ICL+BCG}$, in rare cases up to 90%, while dynamically active clusters have lower fractions, down to 20%, which we find to be independent of the exact implemented baryonic physics. We determine the average increase in $f_{ICL+BCG}$ from stripping and mergers to be between 3-4% per Gyr. $f_{ICL+BCG}$ is tightly traced by the stellar mass ratio between the BCG and both the second (M12) and fourth (M14) most massive cluster galaxy. The average galaxy cluster has assembled half of its halo mass by $z_{f}=0.67$ (about 6 Gyr ago), though individual histories vary significantly from $z_{f}=0.06$ to $z_{f}=1.77$ (0.8 to 10 Gyr ago). As all four cosmological simulations consistently find that $f_{ICL+BCG}$ is an excellent tracer of the cluster dynamical state, upcoming surveys can leverage measurements of $f_{ICL+BCG}$ to statistically quantify the assembly of the most massive structures.

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arXiv2025

The Hierarchical Growth of Bright Central Galaxies and Intracluster Light as Traced by the Magnitude Gap

Using a sample of 2800 galaxy clusters identified in the Dark Energy Survey across the redshift range $0.20 < z < 0.60$, we characterize the hierarchical assembly of Bright Central Galaxies (BCGs) and the surrounding intracluster light (ICL). To quantify hierarchical formation we use the stellar mass - halo mass (SMHM) relation, comparing the halo mass, estimated via the mass-richness relation, to the stellar mass within the BCG+ICL system. Moreover, we incorporate the magnitude gap (M14), the difference in brightness between the BCG (measured within 30 kpc) and 4th brightest cluster member galaxy within 0.5 $R_{200,c}$, as a third parameter in this linear relation. The inclusion of M14, which traces BCG hierarchical growth, increases the slope and decreases the intrinsic scatter, highlighting that it is a latent variable within the BCG+ICL SMHM relation. Moreover, the correlation with M14 decreases at large radii. However, the stellar light within the BCG+ICL transition region (30 kpc - 80 kpc) most strongly correlates with halo mass and has a statistically significant correlation with M14. Since the transition region and M14 are independent measurements, the transition region may grow due to the BCG's hierarchical formation. Additionally, as M14 and ICL result from hierarchical growth, we use a stacked sample and find that clusters with large M14 values are characterized by larger ICL and BCG+ICL fractions, which illustrates that the merger processes that build the BCG stellar mass also grow the ICL. Furthermore, this may suggest that M14 combined with the ICL fraction can identify dynamically relaxed clusters.

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arXiv2023

Dark Energy Survey Year 6 Results: Intra-Cluster Light from Redshift 0.2 to 0.5

Using the full six years of imaging data from the Dark Energy Survey, we study the surface brightness profiles of galaxy cluster central galaxies and intra-cluster light. We apply a ``stacking'' method to over four thousand galaxy clusters identified by the redMaPPer cluster finding algorithm in the redshift range of 0.2 to 0.5. This yields high signal-to-noise radial profile measurements of the central galaxy and intra-cluster light out to 1 Mpc from the cluster center. Using redMaPPer richness as a cluster mass indicator, we find that the intra-cluster light brightness has a strong mass dependence throughout the 0.2 to 0.5 redshift range, and the dependence grows stronger at a larger radius. In terms of redshift evolution, we find some evidence that the central galaxy, as well as the diffuse light within the transition region between the cluster central galaxy and intra-cluster light within 80 kpc from the center, may be growing over time. At larger radii, more than 80 kpc away from the cluster center, we do not find evidence of additional redshift evolution beyond the cluster mass dependence, which is consistent with the findings from the IllustrisTNG hydrodynamic simulation. We speculate that the major driver of intra-cluster light growth, especially at large radii, is associated with cluster mass growth. Finally, we find that the color of the cluster central galaxy and intra-cluster light displays a radial gradient that becomes bluer at a larger radius, which is consistent with a stellar stripping and disruption origin of intra-cluster light as suggested by simulation studies.

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arXiv2023

Satellite Content and Halo Mass of Galaxy Clusters: Comparison between Red-Sequence and Halo-based Optical Cluster Finders

Cluster cosmology depends critically on how optical clusters are selected from imaging surveys. We compare the conditional luminosity function (CLF) and weak lensing halo masses between two different cluster samples at fixed richness, detected within the same volume ($0.1{<}z{<}0.34$) using the red-sequence and halo-based methods. After calibrating our CLF deprojection method against mock galaxy samples, we measure the 3D CLFs by cross-correlating clusters with SDSS photometric galaxies. As expected, the CLFs of red-sequence and halo-based finders exhibit redder and bluer populations, respectively. The red-sequence clusters have a flat distribution of red galaxies at the faint end, while the halo-based clusters host a decreasing faint red and a boosted blue population at the bright end. By comparing subsamples of clusters that have a match between the two catalogues to those without matches, we discover that the CLF shape is mainly caused by the different cluster centroiding. However, the average weak lensing halo mass between the matched and non-matched clusters are consistent with each other in either cluster sample for halos with $λ>30$ (M$_{h}^{WL}{>}1.5\times10^{14}h^{-1}M_{\odot}$). Since the colour preferences of the two cluster finders are almost orthogonal, such a consistency indicates that the scatter in the mass-richness relation of either cluster sample is close to random. Therefore, while the choice of how optical clusters are identified impacts the satellite content, our result suggests that it should not introduce strong systematic biases in cluster cosmology, except for the $λ<30$ regime.

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arXiv2022

Characterising the Intracluster Light over the Redshift Range $0.2 < z < 0.8$ in the DES-ACT Overlap

We characterise the properties and evolution of Bright Central Galaxies (BCGs) and the surrounding intracluster light (ICL) in galaxy clusters identified in overlapping regions of the Dark Energy Survey and Atacama Cosmology Telescope Survey (DES-ACT), covering the redshift range $0.20 $14.4. We also measure the stellar mass - halo mass (SMHM) relation for the BCG+ICL system and find that the slope, $β$, which characterises the dependence of $M_{\rm 200m,SZ}$ on the BCG+ICL stellar mass, increases with radius. The outskirts are more strongly correlated with the halo than the core, which supports that the BCG+ICL system follows a two-phase growth, where recent growth ($z<2$) occurs beyond the BCG's core. Additionally, we compare our observed SMHM relation results to the IllustrisTNG 300-1 cosmological hydrodynamic simulations and find moderate qualitative agreement in the amount of diffuse light. However, the SMHM relation's slope is steeper in TNG300-1 and the intrinsic scatter is lower, likely from the absence of projection effects in TNG300-1. Additionally, we find that the ICL exhibits a colour gradient such that the outskirts are bluer than the core. Moreover, for the lower halo mass clusters (log$_{10}(M_{\rm 200m,SZ}$/M$_{\odot})<$14.59 ), we detect a modest change in the colour gradient's slope with lookback time, which combined with the absence of stellar mass growth may suggest that lower mass clusters have been involved in growth via tidal stripping more recently than their higher mass counterparts.

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arXiv2021

The Observed Evolution of the Stellar Mass - Halo Mass Relation for Brightest Central Galaxies

We quantify evolution in the cluster scale stellar mass - halo mass (SMHM) relation's parameters using 2323 clusters and brightest central galaxies (BCGs) over the redshift range $0.03 \le z \le 0.60$. The precision on inferred SMHM parameters is improved by including the magnitude gap ($\rm m_{gap}$) between the BCG and fourth brightest cluster member (M14) as a third parameter in the SMHM relation. At fixed halo mass, accounting for $\rm m_{gap}$, through a stretch parameter, reduces the SMHM relation's intrinsic scatter. To explore this redshift range, we use clusters, BCGs, and cluster members identified using the Sloan Digital Sky Survey C4 and redMaPPer cluster catalogs and the Dark Energy Survey redMaPPer catalog. Through this joint analysis, we detect no systematic differences in BCG stellar mass, $\rm m_{gap}$, and cluster mass (inferred from richness) between the datsets. We utilize the Pareto function to quantify each parameter's evolution. We confirm prior findings of negative evolution in the SMHM relation's slope (3.5$σ$) and detect negative evolution in the stretch parameter (4.0$σ$) and positive evolution in the offset parameter (5.8$σ$). This observed evolution, combined with the absence of BCG growth, when stellar mass is measured within 50kpc, suggests that this evolution results from changes in the cluster's $\rm m_{gap}$. For this to occur, late-term growth must be in the intra-cluster light surrounding the BCG. We also compare the observed results to Illustris TNG 300-1 cosmological hydrodynamic simulations and find modest qualitative agreement. However, the simulations lack the evolutionary features detected in the real data.

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arXiv2021

Does Concentration Drive the Scatter in the Stellar-to-Halo Mass Relation of Galaxy Clusters?

Concentration is one of the key dark matter halo properties that could drive the scatter in the stellar-to-halo mass relation of massive clusters. We derive robust photometric stellar masses for a sample of brightest central galaxies (BCGs) in SDSS redMaPPer clusters at $0.17<z<0.3$, and split the clusters into two equal-halo mass subsamples by their BCG stellar mass $M_*$. The weak lensing profiles $ΔΣ$ of the two cluster subsamples exhibit different slopes on scales below 1 M$pc/h$. To interpret such discrepancy, we perform a comprehensive Bayesian modelling of the two $ΔΣ$ profiles by including different levels of miscentring effects between the two subsamples as informed by X-ray observations. We find that the two subsamples have the same average halo mass of $1.74 \times 10^{14} M_{\odot}/h$, but the concentration of the low-$M_*$ clusters is $5.87_{-0.60}^{+0.77}$, ${\sim}1.5σ$ smaller than that of their high-$M_*$ counterparts~($6.95_{-0.66}^{+0.78}$). Furthermore, both cluster weak lensing and cluster-galaxy cross-correlations indicate that the large-scale bias of the low-$M_*$, low-concentration clusters are ${\sim}10\%$ higher than that of the high-$M_*$, high-concentration systems, hence possible evidence of the cluster assembly bias effect. Our results reveal a remarkable physical connection between the stellar mass within 20{-}30 k$pc/h$, the dark matter mass within ${\sim}$ 200 k$pc/h$, and the cosmic overdensity on scales above 10 M$pc/h$, enabling a key observational test of theories of co-evolution between massive clusters and their central galaxies.

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arXiv2021

Is diffuse intracluster light a good tracer of the galaxy cluster matter distribution?

We explore the relation between diffuse intracluster light (central galaxy included) and the galaxy cluster (baryonic and dark) matter distribution using a sample of 528 clusters at $0.2\leq z \leq 0.35$ found in the Dark Energy Survey (DES) Year 1 data. The surface brightness of the diffuse light shows an increasing dependence on cluster total mass at larger radius, and appears to be self-similar with a universal radial dependence after scaling by cluster radius. We also compare the diffuse light radial profiles to the cluster (baryonic and dark) matter distribution measured through weak lensing and find them to be comparable. The IllustrisTNG galaxy formation simulation, TNG300, offers further insight into the connection between diffuse stellar mass and cluster matter distributions -- the simulation radial profile of the diffuse stellar component does not have a similar slope with the total cluster matter content, although that of the cluster satellite galaxies does. Regardless of the radial trends, the amount of diffuse stellar mass has a low-scatter scaling relation with cluster's total mass in the simulation, out-performing the total stellar mass of cluster satellite galaxies. We conclude that there is no consistent evidence yet on whether or not diffuse light is a faithful radial tracer of the cluster matter distribution. Nevertheless, both observational and simulation results reveal that diffuse light is an excellent indicator of the cluster's total mass.

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arXiv2019

The Impact of Environment on Late Time Evolution of the Stellar Mass - Halo Mass Relation

At a fixed halo mass, galaxy clusters with higher magnitude gaps have larger brightest central galaxy (BCG) stellar masses. Recent studies have shown that by including the magnitude gap ($\rm m_{gap}$) as a latent parameter in the stellar mass - halo mass (SMHM) relation, we can make more precise measurements on the amplitude, slope, and intrinsic scatter. Using galaxy clusters from the Sloan Digital Sky Survey, we measure the SMHM-$\rm m_{gap}$ relation and its evolution out to $z=0.3$. Using a fixed comoving aperture of 100kpc to define the central galaxy's stellar mass, we report statistically significant negative evolution in the slope of the SMHM relation to $z = 0.3$ ($> 3.5σ$). The steepening of the slope over the last 3.5 Gyrs can be explained by late-time merger activity at the cores of galaxy clusters. We also find that the inferred slope depends on the aperture used to define the radial extent of the central galaxy. At small radii (20kpc), the slope of the SMHM relation is shallow, indicating that the core of the central galaxy is less related to the growth of the underlying host halo. By including all of the central galaxy's light within 100kpc, the slope reaches an asymptote at a value consistent with recent high resolution hydrodynamical cosmology simulations.

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arXiv2018

The Impact of Environment on the Stellar Mass - Halo Mass Relation

A large variance exists in the amplitude of the Stellar Mass - Halo Mass (SMHM) relation for group and cluster-size halos. Using a sample of 254 clusters, we show that the magnitude gap between the brightest central galaxy (BCG) and its second or fourth brightest neighbor accounts for a significant portion of this variance. We find that at fixed halo mass, galaxy clusters with a higher magnitude gap have a higher BCG stellar mass. This relationship is also observed in semi-analytic representations of low-redshift galaxy clusters in simulations. This SMHM-magnitude gap stratification likely results from BCG growth via hierarchical mergers and may link assembly of the halo with the growth of the BCG. Using a Bayesian model, we quantify the importance of the magnitude gap in the SMHM relation using a multiplicative stretch factor, which we find to be significantly non-zero. The inclusion of the magnitude gap in the SMHM relation results in a large reduction in the inferred intrinsic scatter in the BCG stellar mass at fixed halo mass. We discuss the ramifications of this result in the context of galaxy formation models of centrals in group and cluster-sized halos.

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arXiv2016

Classical Oe Stars in the Field of the Small Magellanic Cloud

We present $29\pm1$ classical Oe stars from RIOTS4, a spatially complete, spectroscopic survey of Small Magellanic Cloud (SMC) field OB stars. The two earliest are O6e stars, and four are earlier than any Milky Way (MW) Oe stars. We also find ten Ope stars, showing He~\textsc{i} infill and/or emission; five appear to be at least as hot as $\sim$O7.5e stars. The hottest, star 77616, shows He~\textsc{ii} disk emission, suggesting that even the hottest O stars can form decretion disks, and offers observational support for theoretical predictions that the hottest, fastest rotators can generate He$^+$-ionizing atmospheres. Our data also demonstrate that Ope stars correspond to Oe stars earlier than O7.5e with strong disk emission. We find that in the SMC, Oe stars extend to earlier spectral types than in the MW, and our SMC Oe/O frequency, $0.26\pm0.04$, is much greater than the MW value, $0.03\pm0.01$. These results are consistent with angular momentum transport by stronger winds suppressing decretion disk formation at higher metallicity. In addition, our SMC field Oe star frequency is indistinguishable from that for clusters, which is consistent with the similarity between rotation rates in these environments, and contrary to the pattern for MW rotation rates. Thus, our findings strongly support the viscous decretion disk model and confirm that Oe stars are the high-mass extension of the Be phenomenon. Additionally, we find that Fe~\textsc{ii} emission occurs among Oe stars later than O7.5e with massive disks, and we revise a photometric criterion for identifying Oe stars to $J-[3.6] \geq 0.1$.

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arXiv2014

Discovery of the Earliest-Type Oe Stars in the Small Magellanic Cloud

No classical Oe/Be stars with spectral type earlier than O7.5e have been identified to date in the Milky Way (MW). This is consistent with the decretion disk model because strong stellar winds cause early-type O stars to lose angular momentum, thereby preventing them from rotating fast enough to spin out decretion disks. How- ever, metal-poor O stars have weaker stellar winds, allowing the stars to retain angular momentum. Therefore, low-metallicity environments should promote the formation of Oe stars, including those of earlier spectral types than observed in high-metallicity en- vironments. Using the RIOTS4 survey, a spatially complete spectroscopic survey of Small Magellanic Cloud (SMC) field OB stars taken with the IMACS multi-slit spec- trograph at the Magellan Baade Telescope, we identify 25-31 SMC field Oe stars, which account for 20-28% of SMC field O stars. This fraction is significantly higher than in the MW, where < 10-15% of O stars display the Be phenomenon. We also present 5-7 Oe stars of spectral type ranging from O5.5e to O7e, all earlier spectral types than the earliest MW Oe star. These early type Oe stars represent 20-23% of our SMC Oe stars, a dramatic increase compared to the MW, where no Oe stars have been identified with these early spectral types. Thus, the higher frequencies of Oe stars and their earlier spectral range in the metal-poor SMC are consistent with the decretion disk model.

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