331 research outputs found
Structure and Evolution of Galaxy Clusters: Internal Dynamics of ABCG 209 at z~0.21
We study the internal dynamics of the rich galaxy cluster ABGC 209 on the
basis of new spectroscopic and photometric data. The distribution in redshift
shows that ABCG 209 is a well isolated peak of 112 detected member galaxies at
z=0.209, characterised by a high value of the line-of-sight velocity
dispersion, sigma_v=1250-1400 Km/s, on the whole observed area (1 Mpc/h from
the cluster center), that leads to a virial mass of M=1.6-2.2x10^15 M_sun
within the virial radius, assuming the dynamical equilibrium. The presence of a
velocity gradient in the velocity field, the elongation in the spatial
distribution of the colour-selected likely cluster members, the elongation of
the X-ray contour levels in the Chandra image, and the elongation of cD galaxy
show that ABCG 209 is characterised by a preferential NW-SE direction. We also
find a significant deviation of the velocity distribution from a Gaussian, and
relevant evidence of substructure and dynamical segregation. All these facts
show that ABCG 209 is a strongly evolving cluster, possibly in an advanced
phase of merging.Comment: 26 pages, 14 figures. A&A in pres
Extended stellar kinematics of elliptical galaxies in the Fornax cluster
We present extended stellar kinematics for a sample of 13 elliptical galaxies
in the Fornax cluster. Major-axis velocity dispersion profiles (VDPs) and
rotation curves (RCs) are given for 12 of the galaxies. A major feature of this
data is the spatial extension: for 8 galaxies the data extends beyond 1 R_e,
and for 5 it extends beyond 2 R_e. Compared to the previously available data,
this corresponds to an increase in spatial coverage by a factor from 1 to 5.
Five of the ellipticals in the sample turn out to be rotationally-supported
systems, having positive rotation parameter log (V/sigma)*. One of these five,
and another 3 galaxies from the remaining sample, display evidence for bar-like
kinematics. The data indicate that the true number of `dynamically hot' stellar
systems, is much lower than previously thought: of the Es in the present sample
only 1/4 are confirmed as `pressure-supported' systems. The data reveal a host
of individual peculiarities, like: wiggles, strong gradients, and asymmetries
in the rotation curve and/or in the velocity dispersion profile, thus showing
that the presence of kinematically distinct components and/or triaxiality is a
common characteristic of this class of object.Comment: 27 pages, includes 15 eps figures. Accepted for publication in A&A
Sup
Is there a relationship between the mass of a SMBH and the kinetic energy of its host elliptical galaxy?
We use a restricted sample of elliptical galaxies, whose kinematical
parameters inside the semimajor axis were calculated correcting the effect of
the integration of the light along the line of sight, in order to analyze a
possible relationship between the mass of a Supermassive Black Hole (SMBH) and
the kinetic energy of random motions in the host galaxy. We find with depending on
the different fitting methods and samples used. This result could be
interpreted as a new fundamental relationship or as a new way to explain the
old law. In fact, the relations of the velocity dispersion
both with the mass of the SMBH () and with the
mass of the host galaxy () induce us to infer an
almost direct proportionality: . A similar
relationship is found for the total kinetic energy involving the rotation
velocity too.Comment: 16 pages, 3 figures, 1 Table, accepted for publication in IJMP
Oscillating universes as eigensolutions of cosmological Schr\"odinger equation
We propose a cosmological model which could explain, in a very natural way,
the apparently periodic structures of the universe, as revealed in a series of
recent observations. Our point of view is to reduce the cosmological
Friedman--Einstein dynamical system to a sort of Schr\"odinger equation whose
bound eigensolutions are oscillating functions. Taking into account the
cosmological expansion, the large scale periodic structure could be easily
recovered considering the amplitudes and the correlation lengths of the galaxy
clusters.Comment: 12 pages, Latex, submitted to Int. Jou. of Theor. Phy
Shapley Supercluster Survey: Ram-Pressure Stripping vs. Tidal Interactions in the Shapley Supercluster
We present two new examples of galaxies undergoing transformation in the
Shapley supercluster core. These low-mass (stellar mass from 0.4E10 to 1E10
Msun) galaxies are members of the two clusters SC-1329-313 (z=0.045) and
SC-1327-312 (z=0.049). Integral-field spectroscopy complemented by imaging in
ugriK bands and in Halpha narrow-band are used to disentangle the effects of
tidal interaction (TI) and ram-pressure stripping (RPS). In both galaxies,
SOS-61086 and SOS-90630, we observe one-sided extraplanar ionized gas extending
respectively 30kpc and 41kpc in projection from their disks. The galaxies'
gaseous disks are truncated and the kinematics of the stellar and gas
components are decoupled, supporting the RPS scenario. The emission of the
ionized gas extends in the direction of a possible companion for both galaxies
suggesting a TI. The overall gas velocity field of SOS-61086 is reproduced by
ad hoc N-body/hydrodynamical simulations of RPS acting almost face-on and
starting about 250Myr ago, consistent with the age of the young stellar
populations. A link between the observed gas stripping and the cluster-cluster
interaction experienced by SC-1329-313 and A3562 is suggested. Simulations of
ram pressure acting almost edge-on are able to fully reproduce the gas velocity
field of SOS-90630, but cannot at the same time reproduce the extended tail of
outflowing gas. This suggests that an additional disturbance from a TI is
required. This study adds a piece of evidence that RPS may take place in
different environments with different impacts and witnesses the possible effect
of cluster-cluster merger on RPS.Comment: 27 pages, 28 figures, MNRAS accepte
Extended stellar kinematics of elliptical galaxies in the Fornax cluster
We present extended stellar kinematics for a sample of elliptical galaxies in the Fornax cluster. Out of the 13 galaxies presented here, five (FCC 119, FCC 136, NGC 1373, NGC 1428, FCC 335) have no previously published kinematical data. Major-axis velocity dispersion profiles (VDPs) and rotation curves (RCs) are given for 12 of the galaxies. A major feature of this data is the spatial extension: for 8 galaxies the data extends beyond 1 R_e, and for 5 it extends beyond 2 R_e. Compared to the previously available data, this corresponds to an increase in spatial coverage by a factor from 1 to 5. The present sample represents 86% of the ellipticals in Fornax brighter than B_T = 15 mag. Five of the ellipticals in the sample turn out to be rotationally-supported systems, having positive rotation parameter log ((V)/(sigma ))(*) . One of these five, and another 3 galaxies from the remaining sample, display evidence for bar-like kinematics. The data indicate that the yes number of ``dynamically hot'' stellar systems, is much lower than previously thought: of the Es in the present sample only 1/4 are confirmed as ``pressure-supported'' systems. The data reveal a host of individual peculiarities, like: wiggles, strong gradients, and asymmetries in the rotation curve and/or in the velocity dispersion profile, thus showing that the presence of kinematically distinct components and/or triaxiality is a common characteristic of this class of object. Based on observations collected at Siding Spring Observatory. Table 3 is presented in electronic form only, and is available from the CDS, Strasbourg via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.htm
UV--NIR Restframe Luminosity Functions of the Galaxy Cluster EIS0048 at z~0.64
We derive the galaxy luminosity functions in V, R, I, and K bands of the
cluster EIS 0048 at z~0.64 from data taken at the ESO Very Large Telescope. The
data span the restframe wavelength range from UV, which is sensitive to even
low rates of star formation, to the NIR, which maps the bulk of the stellar
mass. By comparing our data and previous results with pure luminosity evolution
models, we conclude that bright (M<= M^*+1) cluster galaxies are already
assembled at z~1 and that star formation is almost completed at z~1.5.Comment: 11 pages, 5 figures. A&A accepte
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