Ages of S0 and Elliptical Galaxies in the Coma Cluster

2001 ◽  
Vol 563 (1) ◽  
pp. 118-123 ◽  
Author(s):  
Bianca M. Poggianti ◽  
Terry J. Bridges ◽  
Dave Carter ◽  
Bahram Mobasher ◽  
M. Doi ◽  
...  
Keyword(s):  
Elliptical Galaxies ◽  
Coma Cluster

scholarly journals The Dark Halo – Spheroid Conspiracy

2012 ◽  
Vol 8 (S295) ◽  
pp. 208-208
Author(s):  
Rhea-Silvia Remus ◽  
Andreas Burkert ◽  
Klaus Dolag ◽  
Peter H. Johansson ◽  
Thorsten Naab ◽  
...  
Keyword(s):  
Elliptical Galaxies ◽  
Total Density ◽  
Dark Halo ◽  
Coma Cluster ◽  
Density Profiles ◽  
Stellar Component ◽  
Strong Lensing ◽  
The Galaxy ◽  
Good Agreement

AbstractObservational results from strong lensing and dynamical modeling indicate that the total density profiles of early-type galaxies are close to isothermal, i.e. ρtot ∝ rγ with γ ≈ −2. To understand the origin of this universal slope we study a set of simulated spheroids formed in cosmological hydrodynamical zoom-in simulations (see Oser et al. 2010 for more details). We find that the total stellar plus dark matter density profiles of all our simulations on average can be described by a power law with a slope of γ ≈ −2.1, with a tendency towards steeper slopes for more compact, lower mass ellipticals, while the total intrinsic velocity dispersion is flat for all simulations, independent of the values of γ. Our results are in good agreement with observations of Coma cluster ellipticals (Thomas et al. 2007) and results from strong lensing (Sonnenfeld et al. 2012). We find that for z ≳ 2 the majority of the stellar build-up occurs through in-situ star formation, i.e. the gas falls to the center of the galaxy and forms stars, causing the galaxy to be more compact and thus the stellar component to be more dominant. As a result, the total density slopes at z ≈ 2 are generally steeper (around γ ≈ −3). Between z = 2 and z = 0 galaxies grow mostly through dry merging, with each merging event shifting the slope more towards γ ≈ −2. We conclude from our simulations that the steepness of the slope of present day galaxies is a signature of the importance of mostly dry mergers in the formation of an elliptical, and suggest that all elliptical galaxies will with time end up in a configuration with a density slope of γ ≈ −2. For a more detailed analysis with a larger sample of simulations see Remus et al. (2013).

scholarly journals Color of Dwarf Galaxies in the Coma Cluster

1999 ◽  
Vol 183 ◽  
pp. 160-160
Author(s):  
S. Okamura ◽  
Y. Komiyama ◽  
M. Sekiguchi ◽  
N. Kashikawa ◽  
K. Shimasaku ◽  
...  
Keyword(s):  
Dwarf Galaxies ◽  
Ccd Camera ◽  
Elliptical Galaxies ◽  
Cluster Center ◽  
Coma Cluster ◽  
Control Field ◽  
Magnitude Range ◽  
Variable Aperture ◽  
The Mean ◽  
William Herschel

We observed three 0.44 square degree fields centered on the Coma cluster center (Coma-1), about 1 degree SW of the Coma center (Coma-3), and on a control field in SA57 with the mosaic CCD camera at the prime focus of the 4.2-m William Herschel Telescope. We detected 5628, 5020, and 4323 galaxies down to R = 22 mag in Coma-1, Coma-3, and SA57 fields, respectively. We measure the magnitude and color within the variable aperture r90 in which about 90% of the total flux is included. The histograms of (B–R) colors of galaxies are made for four magnitude bins of width ΔR = 2 mag covering 13 < R < 21 mag for each of the three fields. The mean colors and the 1σ scatters of the Coma galaxies are obtained by a histogram subtraction technique (Coma-1/3 minus SA57). We find a very shallow slope of the color-magnitude relation (CMR), Δ(B–R)/ΔR=−0.0037, which indicates nearly a constant (B–R) color over 6 magnitude in 15 < R < 21 mag (−19.5 < MR < −13.5 at Coma cluster). Dwarf galaxies are dominant in this magnitude range, and we conclude that the mean color of dwarf galaxies in the Coma clusters is nearly constant at (B–R) ∼ 1.6–1.7, which is similar to the color of the faint end of giant elliptical galaxies.

scholarly journals Redshift Asymmetries and the Missing Mass

1987 ◽  
Vol 124 ◽  
pp. 503-506
Author(s):  
Gene G. Byrd ◽  
Mauri J. Valtonen
Keyword(s):  
Spiral Galaxies ◽  
Elliptical Galaxies ◽  
Coma Cluster ◽  
Missing Mass ◽  
Cluster Of Galaxies ◽  
Or Groups ◽  
Other Information ◽  
Massive Halos ◽  
The Universe ◽  
Very High

We study the existence of missing mass in the outermost regions of galaxies not accessible to study by rotation curve methods. We consider binary galaxies, groups and clusters of galaxies. Arp has previously explained redshift asymmetries in pairs or groups with “non-Doppler redshifts”. Instead, we propose the asymmetries indicate contamination by optical pairs or by members which are not gravitationally bound to the group or pair. The group samples which are commonly used to justify very high missing mass values in spiral galaxies (>> the mass detected by rotation curves) also exhibit significant redshift asymmetries. From this and other information, we conclude that spiral galaxies do not possess very massive halos. Only the rare giant elliptical galaxies, such as the binary pair in the center of the Coma Cluster of galaxies, apparently possess extremely massive halos. Dynamical effects of such giants lead to overestimates of the mass of clusters. The evidence indicates that missing mass sufficient to close the universe is not concentrated in individual galaxies, groups or rich clusters.

scholarly journals Effect of Environment on the Underlying Stellar Populations of Dwarf Elliptical Galaxies in the Coma Cluster

2009 ◽  
Author(s):  
A. Matković ◽  
R. Guzmán ◽  
P. Sánchez-Blázquez ◽  
N. Cardiel ◽  
J. Gorgas ◽  
...  
Keyword(s):  
Stellar Populations ◽  
Elliptical Galaxies ◽  
Coma Cluster ◽  
Dwarf Elliptical Galaxies
Sign in / Sign up

Export Citation Format

Share Document