scholarly journals Diversity in the stellar velocity dispersion profiles of a large sample of brightest cluster galaxies z ≤ 0.3

2018 ◽  
Vol 477 (1) ◽  
pp. 335-358 ◽  
Author(s):  
S I Loubser ◽  
H Hoekstra ◽  
A Babul ◽  
E O'Sullivan
Keyword(s):  
Velocity Dispersion ◽  
Large Sample ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
Stellar Velocity

scholarly journals Velocity dispersion of brightest cluster galaxies in cosmological simulations

2021 ◽  
Vol 507 (4) ◽  
pp. 5780-5795
Author(s):  
I Marini ◽  
S Borgani ◽  
A Saro ◽  
G L Granato ◽  
C Ragone-Figueroa ◽  
...  
Keyword(s):  
Dark Matter ◽  
Velocity Dispersion ◽  
Stellar Envelope ◽  
Cluster Galaxies ◽  
Massive Galaxies ◽  
Brightest Cluster Galaxies ◽  
Stellar Velocity ◽  
Intracluster Light ◽  
The Universe ◽  
Good Agreement

ABSTRACT Using the DIANOGA hydrodynamical zoom-in simulation set of galaxy clusters, we analyse the dynamics traced by stars belonging to the brightest cluster galaxies (BCGs) and their surrounding diffuse component, forming the intracluster light (ICL), and compare it to the dynamics traced by dark matter and galaxies identified in the simulations. We compute scaling relations between the BCG and cluster velocity dispersions and their corresponding masses (i.e. $M_\mathrm{BCG}^{\star }$–$\sigma _\mathrm{BCG}^{\star }$, M200–σ200, $M_\mathrm{BCG}^{\star }$–M200, and $\sigma _\mathrm{BCG}^{\star }$–σ200), we find in general a good agreement with observational results. Our simulations also predict $\sigma _\mathrm{BCG}^{\star }$–σ200 relation to not change significantly up to redshift z = 1, in line with a relatively slow accretion of the BCG stellar mass at late times. We analyse the main features of the velocity dispersion profiles, as traced by stars, dark matter, and galaxies. As a result, we discuss that observed stellar velocity dispersion profiles in the inner cluster regions are in excellent agreement with simulations. We also report that the slopes of the BCG velocity dispersion profile from simulations agree with what is measured in observations, confirming the existence of a robust correlation between the stellar velocity dispersion slope and the cluster velocity dispersion (thus, cluster mass) when the former is computed within 0.1R500. Our results demonstrate that simulations can correctly describe the dynamics of BCGs and their surrounding stellar envelope, as determined by the past star formation and assembly histories of the most massive galaxies of the Universe.

scholarly journals Dynamical masses of brightest cluster galaxies I: stellar velocity anisotropy and mass-to-light ratios

2020 ◽  
Vol 496 (2) ◽  
pp. 1857-1880 ◽  
Author(s):  
S I Loubser ◽  
A Babul ◽  
H Hoekstra ◽  
Y M Bahé ◽  
E O’Sullivan ◽  
...  
Keyword(s):  
Gravitational Lensing ◽  
Velocity Dispersion ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Cluster Galaxies ◽  
Velocity Anisotropy ◽  
Brightest Cluster Galaxies ◽  
Stellar Velocity ◽  
Total Light ◽  
Intracluster Light

ABSTRACT We investigate the stellar and dynamical mass profiles in the centres of 25 brightest cluster galaxies (BCGs) at redshifts of 0.05 ≤ z ≤ 0.30. Our spectroscopy enables us to robustly measure the Gauss–Hermite higher order velocity moments h3 and h4, which we compare to measurements for massive early-type galaxies, and central group galaxies. We measure positive central values for h4 for all the BCGs. We derive the stellar mass-to-light ratio ($\Upsilon _{\star \rm DYN}$), and velocity anisotropy (β) based on a multi-Gaussian expansion (MGE) and axisymmetric Jeans Anisotropic Methods (cylindrically and spherically aligned). We explicitly include a dark matter halo mass component, which is constrained by weak gravitational lensing measurements for these clusters. We find a strong correlation between anisotropy and velocity dispersion profile slope, with rising velocity dispersion profiles corresponding to tangential anisotropy and decreasing velocity dispersion profiles corresponding to radial anisotropy. The rising velocity dispersion profiles can also indicate a significant contribution from the intracluster light (ICL) to the total light (in projection) in the centre of the galaxy. For a small number of BCGs with rising velocity dispersion profiles, a variable stellar mass-to-light ratio can also account for the profile shape, instead of tangential anisotropy or a significant ICL contribution. We note that, for some BCGs, a variable βz(r) (from radial to tangential anisotropy) can improve the model fit to the observed kinematic profiles. The observed diversity in these properties illustrates that BCGs are not the homogeneous class of objects they are often assumed to be.

scholarly journals Clocking the formation of today’s largest galaxies: wide field integral spectroscopy of brightest cluster galaxies and their surroundings

2019 ◽  
Vol 491 (2) ◽  
pp. 2617-2638 ◽  
Author(s):  
Louise O V Edwards ◽  
Matthew Salinas ◽  
Steffanie Stanley ◽  
Priscilla E Holguin West ◽  
Isabella Trierweiler ◽  
...  
Keyword(s):  
Velocity Dispersion ◽  
Minor Component ◽  
High Signal ◽  
Wide Field ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
The Galaxy ◽  
Formation And Evolution ◽  
Intracluster Light ◽  
A Minor

ABSTRACT The formation and evolution of local brightest cluster galaxies (BCGs) is investigated by determining the stellar populations and dynamics from the galaxy core, through the outskirts and into the intracluster light (ICL). Integral spectroscopy of 23 BCGs observed out to $4\, r_{e}$ is collected and high signal-to-noise regions are identified. Stellar population synthesis codes are used to determine the age, metallicity, velocity, and velocity dispersion of stars within each region. The ICL spectra are best modelled with populations that are younger and less metal-rich than those of the BCG cores. The average BCG core age of the sample is $\rm 13.3\pm 2.8\, Gyr$ and the average metallicity is $\rm [Fe/H] = 0.30\pm 0.09$, whereas for the ICL the average age is $\rm 9.2\pm 3.5\, Gyr$ and the average metallicity is $\rm [Fe/H] = 0.18\pm 0.16$. The velocity dispersion profile is seen to be rising or flat in most of the sample (17/23), and those with rising values reach the value of the host cluster’s velocity dispersion in several cases. The most extended BCGs are closest to the peak of the cluster’s X-ray luminosity. The results are consistent with the idea that the BCG cores and inner regions formed quickly and long ago, with the outer regions and ICL forming more recently, and continuing to assemble through minor merging. Any recent star formation in the BCGs is a minor component, and is associated with the cluster cool core status.

scholarly journals Stellar population gradients in brightest cluster galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 316-316
Author(s):  
S. I. Loubser ◽  
P. Sánchez-Blázquez
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
Elliptical Galaxies ◽  
Negative Slope ◽  
High Quality ◽  
X Ray ◽  
Cluster Galaxies ◽  
Central Galaxy ◽  
Brightest Cluster Galaxies

AbstractWe present the stellar population and velocity dispersion gradients for a sample of 24 brightest cluster galaxies (BCGs) in the nearby Universe for which we have obtained high quality long-slit spectra at the Gemini telescopes. With the aim of studying the possible connection between the formation of the BCGs and their host clusters, we explore the relations between the stellar population gradients and properties of the host clusters, as well as the possible connections between the stellar population gradients and other properties of the galaxies. We find mean stellar population gradients (negative Δ[Z/H]/log r gradient of − 0.285 ± 0.064; small positive Δlog(age)/log r gradient of +0.069 ± 0.049; and null Δ[E/Fe]/log r gradient of -0.008 ± 0.032), that are consistent with those of normal massive elliptical galaxies. However, we find a trend between metallicity gradients and velocity dispersion (with a negative slope of − 1.616 ± 0.539), that is not found for the most massive ellipticals. Furthermore, we find trends between the metallicity gradients and K-band luminosities (with a slope of 0.173 ± 0.081) as well as the distance from the BCG to the X-ray peak of the host cluster (with a slope of − 7.546 ± 2.752). The latter indicates a possible relation between the formation of the cluster and that of the central galaxy.

scholarly journals Mass–Velocity Dispersion Relation in MaNGA Brightest Cluster Galaxies

2021 ◽  
Vol 917 (2) ◽  
pp. L24
Author(s):  
Yong Tian ◽  
Han Cheng ◽  
Stacy S. McGaugh ◽  
Chung-Ming Ko ◽  
Yun-Hsin Hsu
Keyword(s):  
Dispersion Relation ◽  
Mass Velocity ◽  
Velocity Dispersion ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies

scholarly journals Line-Strength Profiles in Early-Type Galaxies

1995 ◽  
Vol 164 ◽  
pp. 453-453
Author(s):  
David Fisher ◽  
Garth Illingworth ◽  
Marijn Franx
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
Line Strength ◽  
Strong Correlations ◽  
Metal Line ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
The Mean ◽  
S0 Galaxies ◽  
Line Strengths

Line-strengths and their gradients in Mg, Fe, and Hβ have been determined for a sample of 9 brightest cluster (BCG), 7 elliptical, and 15 S0 galaxies in order to study their stellar populations and investigate their relationship to one another. We find that BCGs follow the same relationship between central Mgb line-strength and central velocity dispersion found for ellipticals while the S0 galaxies show significant scatter with respect to this relation. Brightest cluster galaxies are in agreement with the known trend towards more massive ellipticals having larger [Mg/Fe] ratios while the internal gradients within our BCG and E galaxies are consistent with a roughly constant [Mg/Fe] ratio. We find that a correlation exists between the central [Mg/Fe] ratio and average Hβ line-strength in the sense that BCG and E galaxies with larger [Mg/Fe] ratios have lower Hβ strengths. For our BCG and E galaxies, Hβ is the best predictor of [Mg/Fe] ratio. The Mgb metallicity gradients for BCGs and ellipticals are similar and consistent with a reduction in the mean metallicity of the stellar population by about a factor of 2 over a factor of ten in radius. No strong correlations are found between the metallicity gradient sizes and either kinematic or line-strength parameters of the E and BCG galaxies. The S0 disks display roughly constant Mg, Fe, and Hβ line-strengths with radius indicating that they have uniform age and metallicity throughout. S0 galaxy minor axes ‘bulge’ metal line-strength gradients are similar to elliptical gradients and fall to values lower than those found in the disks.

scholarly journals The HectoMAP Cluster Survey: Spectroscopically Identified Clusters and their Brightest Cluster Galaxies (BCGs)

2021 ◽  
Vol 923 (2) ◽  
pp. 143
Author(s):  
Jubee Sohn ◽  
Margaret J. Geller ◽  
Ho Seong Hwang ◽  
Antonaldo Diaferio ◽  
Kenneth J. Rines ◽  
...  
Keyword(s):  
Velocity Dispersion ◽  
Number Density ◽  
Lower Mass ◽  
Strong Concentration ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
Redshift Survey ◽  
Minor Mergers ◽  
Reliability Systems ◽  
The Universe

Abstract We apply a friends-of-friends (FoF) algorithm to identify galaxy clusters and we use the catalog to explore the evolutionary synergy between brightest cluster galaxies (BCGs) and their host clusters. We base the cluster catalog on the dense HectoMAP redshift survey (2000 redshifts deg−2). The HectoMAP FoF catalog includes 346 clusters with 10 or more spectroscopic members within the range 0.05 < z < 0.55 and with a median z = 0.29. We list these clusters and their members. We also include central velocity dispersions (σ *,BCG) for the FoF cluster BCGs, a distinctive feature of the HectoMAP FoF catalog. HectoMAP clusters with higher galaxy number density (80 systems) are all genuine clusters with a strong concentration and a prominent BCG in Subaru/Hyper Suprime-Cam images. The phase-space diagrams show the expected elongation along the line of sight. Lower-density systems include some low reliability systems. We establish a connection between BCGs and their host clusters by demonstrating that σ *,BCG /σ cl decreases as a function of cluster velocity dispersion (σ cl), in contrast, numerical simulations predict a constant σ *,BCG/σ cl. Sets of clusters at two different redshifts show that BCG evolution in massive systems is slow over the redshift range z < 0.4. The data strongly suggest that minor mergers may play an important role in BCG evolution in clusters with σ cl ≳ 300 km s−1. For lower mass systems (σ cl < 300 km s−1), major mergers may play a significant role. The coordinated evolution of BCGs and their host clusters provides an interesting test of simulations in high-density regions of the universe.

scholarly journals The Detectability of Seyfert 2 Galaxies with Hidden Broad-Line Regions

2006 ◽  
Vol 2 (S235) ◽  
pp. 77-77
Author(s):  
W. Bian
Keyword(s):  
Black Holes ◽  
Velocity Dispersion ◽  
Broad Line ◽  
Massive Black Holes ◽  
Large Sample ◽  
Stellar Velocity ◽  
The Masses

The detectability of Seyfert 2 galaxies (Sy2s) with hidden broad-line regions(HBLRs) is still a question open to debate. Using a large sample of 90 Seyfert 2 galaxies (Sy2s) with spectropolarimetric observations (Gu & Huang 2002), we tested the suggestion that the presence of hidden broad-line regions (HBLRs) in Sy2s is dependent upon the Eddington ratio (Nicastro et al. 2003). The stellar velocity dispersion and the extinction-corrected [O III] luminosity are used to derive the masses of central super-massive black holes and the Eddington ratios. The main conclusion are summarized as follows.

Stellar and dynamical masses of brightest cluster galaxies

2019 ◽  
Vol 14 (S353) ◽  
pp. 255-256
Author(s):  
S. I. Loubser
Keyword(s):  
Velocity Dispersion ◽  
Dark Matter Halo ◽  
Dynamical Mass ◽  
Cluster Galaxies ◽  
Central Values ◽  
Brightest Cluster Galaxies ◽  
Velocity Moments ◽  
Massive Clusters ◽  
Mass Component ◽  
Mass Profiles

AbstractWe investigate the stellar and dynamical mass profiles of 32 brightest cluster galaxies (BCGs, MK = −25.7 to −27.8 mag) in massive clusters (0.05 < z < 0.30), and in particular the rising velocity dispersion profiles of 23 of these BCGs found in Loubser et al. (2018). We make comprehensive measurements of the Gauss-Hermite higher order velocity moments h3 and h4, and find positive central values for h4 for all the BCGs. We model the stellar and dynamical mass profiles of 25 of the BCGs using the Multi-Gaussian Expansion (MGE) and Jeans Anisotropic Method (JAM) for an axisymmetric case, deriving the stellar mass-to-light ratio (ϒ*DYN), and anisotropy (βz). We further explicitly add a dark matter halo mass component (MDM within r200) which we constrain from weak lensing results. In this proceedings, we summarise the study and show an example of the results.

scholarly journals Possible Relations between Brightest Central Galaxies and Their Host Galaxies Clusters and Groups

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
R. M. Samir ◽  
A. A. Shaker
Keyword(s):  
Velocity Dispersion ◽  
Absolute Magnitude ◽  
Effective Radius ◽  
Sloan Digital Sky Survey ◽  
The Other ◽  
Host Galaxies ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
Sky Survey ◽  
Environmental Relations

Abstract The r-band of the Sloan Digital Sky Survey (SDSS) for 17,924 brightest cluster galaxies (BCGs) in clusters and groups within 0.02 ⩽ z ⩽ 0.20 are used to study possible environmental relations affecting the nature of these galaxies. We find a correlation between BCGs physical properties (the effective radius (Re ), absolute magnitude and central velocity dispersion (σ 0)) and their host groups and clusters velocity dispersion (σcl ). This type of relations suggests that the most massive groups or clusters host larger central galaxies. On the other hand, the σ 0/σcl ratio as a function of σcl is consistent with [10].

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