A Census of Baryons in Galaxy Clusters and Groups

By Anthony H. Gonzalez, Dennis Zaritsky, Ann Zabludoff. Proceedings of the International Astronomical Union, 2007

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We determine the contribution of stars in galaxies, intracluster stars, and the intracluster medium to the total baryon budget in nearby galaxy clusters and groups. We find that the baryon mass fraction (fb ≡ Ωb/Ωm) within r500 is constant for systems with M500 between 6 × 1013 and 1 × 1015 M☉. Although fb is lower than the WMAP value, the shortfall is on the order of both the observational systematic uncertainties and the depletion of baryons within r500 that is predicted by simulations. The data therefore provide no compelling evidence for undetected baryonic components, particularly any that would be expected to vary in importance with cluster mass. A unique feature of the current analysis is direct inclusion of the contribution of intracluster light (ICL) in the baryon budget. With the addition of the ICL to the stellar mass in galaxies, the increase in X-ray gas mass fraction with increasing total mass is entirely accounted for by a decrease in the total stellar mass fraction, supporting the argument that the behavior of both the stellar and X-ray gas components is dominated by a decrease in star formation efficiency in more massive environments. Within just the stellar component, the fraction of the total stellar luminosity in the central, giant brightest cluster galaxy (BCG) and ICL (hereafter the BCG+ICL component) decreases as velocity dispersion (σ) increases for systems with 145 km s-1 ≤ σ ≤ 1026 km s-1, suggesting that the BCG+ICL component, and in particular the dominant ICL component, grows less efficiently in higher mass environments. The degree to which this behavior arises from our sample selection, which favored systems with central, giant elliptical galaxies, remains unclear. A more robust result is the identification of low-mass groups with large BCG+ICL components, demonstrating that the creation of "intracluster" stars does not require a massive cluster environment. Within r500 and r200, the BCG+ICL contributes on average 40% and 33% of the total stellar light, respectively, for the clusters and groups in our sample. Because these fractions are functions of both enclosed radius and system mass, care should be exercised when comparing these values with other studies and simulations.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/6545f3981d9022d349414a8c607f42e193f0411a

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Citations in the corpus

CHANDRA STUDIES OF THE X-RAY GAS PROPERTIES OF GALAXY GROUPS (2008, background): “Gonzalez et al. (2007) included the intracluster stellar mass and found: f∗,500,Gonzalez = 0.0380(M500/10 14M⊙) −0.64 (adjusted to our cosmology).”
SIMULATIONS OF THE SUNYAEV–ZEL'DOVICH POWER SPECTRUM WITH ACTIVE GALACTIC NUCLEUS FEEDBACK (2010, background): “…agree with recently obtained observational ones that have been constructed from X-ray data; the scaling relations between the cluster mass and X-ray based Compton-Y (Arnaud et al. 2009) also agree; as do the integrated stellar and gas mass fractions (Gonzalez et al. 2007; Afshordi et al. 2007).”
CHANDRA CLUSTER COSMOLOGY PROJECT. II. SAMPLES AND X-RAY DATA REDUCTION (2008, methodology): “Observational support for this model is provided by the recent work of Gonzalez et al. (2007) who show that the trend in stellar mass fraction, fstars(M), is such that it roughly compensates for decreasing fg in low-mass clusters, making fstars + fg nearly constant at M500 1014 h−1M clusters,…”
UniverseMachine: The correlation between galaxy growth and dark matter halo assembly from z = 0−10 (2018, result): “This is ∼ 0.3 dex lower than past results (e.g. Gonzalez et al. 2007; Moster et al. 2013; Behroozi et al. 2013e), as the SMFs used in this study assign more light to the central galaxy that previously would have been assigned to the IHL (Bernardi et al. 2013; Kravtsov et al. 2018).”
STELLAR AND TOTAL BARYON MASS FRACTIONS IN GROUPS AND CLUSTERS SINCE REDSHIFT 1 (2009, methodology): “For example, if the ICL mass-to-light ratio used in Gonzalez et al. (2007) is overestimated by a factor 2, it translates in tghe systematic overestimation of the baryon mass fraction by 10%.”
Towards a realistic population of simulated galaxy groups and clusters (2013, background): “As discussed in detail in Budzynski et al. (2014), there is a difference in the slope of the trend of the stellar mass/light with halo mass that they measure and that measured by Gonzalez et al. (2007) (and now Gonzalez et al. 2013).”
X-ray spectroscopy of the Virgo Cluster out to the virial radius (2011, background): “Given that the stellar over ICM baryon fraction of clusters is decreasing with the increasing cluster mass (e.g. Gonzalez et al. 2007) explaining the higher metal content of the more massive clusters would be challenging.”
THE SUPERNOVA DELAY TIME DISTRIBUTION IN GALAXY CLUSTERS AND IMPLICATIONS FOR TYPE-Ia PROGENITORS AND METAL ENRICHMENT (2010, methodology): “However, Gonzalez et al. (2007) used the relation obtained by Cappellari et al. (2006) between the kinematically measured total-mass-to-luminosity ratio, M/L of nearby ellipticals and their I-band luminosity.”
A Fitting Formula for the Merger Timescale of Galaxies in Hierarchical Clustering (2007, result): “This ratio is in reasonable agreement with the observed values of galaxy groups(Gonzalez et al. 2007; Lin et al. 2003).”
Jet-regulated cooling catastrophe (2010, methodology): “On the other hand, the simulation with AGN feedback shows reasonable agreement with the stellar fraction estimated from X-ray measurements by Gonzalez et al. (2007) and Giodini et al. (2009), but still overestimates the stellar fraction from near-infrared data by Lin et al. (2003) by about a factor…”
ANCIENT LIGHT FROM YOUNG COSMIC CITIES: PHYSICAL AND OBSERVATIONAL SIGNATURES OF GALAXY PROTO-CLUSTERS (2013, background): “…ICM on scales of about 1 Mpc. Galaxy kinematics and gravitational lensing studies show that cluster galaxies are embedded in a massive halo of dark matter with mass of& 1014 M⊙, which weighs about five times more than its baryonic contents (Gonzalez et al. 2007; Giodini et al. 2009; Andreon 2010).”
THE GALAXY CONTENT OF SDSS CLUSTERS AND GROUPS (2007, background): “Nonetheless, we show below that using these galaxies as a tracer of the total matter distribution does result in a reasonable approximation of r200, a finding also noted by Gonzalez et al. (2007).”
Intracluster stars in simulations with active galactic nucleus feedback (2010, methodology): “For a mean cluster mass of 7 − 8 × 1013M⊙ they find that about ∼ 22% of the stars reside in the BCG, while roughly ∼ 11% are intracluster stars within a fixed aperture of 500 kpc. Gonzalez et al. (2005, 2007) describe another study for which a significant number of clusters and groups were observed.”
Virial Scaling of Massive Dark Matter Halos: Why Clusters Prefer a High Normalization Cosmology (2007, background): “Recent studies that include a diffuse light contribution emphasize the mass dependence of this fraction; stars and hot gas are comparable mass components at M200 ¼ 1014h 1M (Gonzalez et al. 2007).”
GALAXY CLUSTER BARYON FRACTIONS REVISITED (2013, methodology): “Additional details of this procedure are discussed in Gonzalez et al. (2007).”