Compact and Isolated Groups of Galaxies in the Local Universe

2008 ◽  
pp. 329-330
Author(s):  
Julio Saucedo-Morales ◽  
P. Loera-González ◽  
A. Santillán-González
Keyword(s):  
Local Universe ◽  
Groups Of Galaxies

scholarly journals Poor Groups Around Strong Gravitational Lenses

2006 ◽  
Vol 2 (S235) ◽  
pp. 230-230
Author(s):  
Ivelina Momcheva ◽  
Kurtis Williams ◽  
Ann Zabludoff ◽  
Charles Keeton
Keyword(s):  
Galaxy Evolution ◽  
Velocity Dispersion ◽  
Gravitational Lenses ◽  
Local Universe ◽  
Groups Of Galaxies ◽  
Hot Gas ◽  
Gas Kinematics ◽  
The Galaxy ◽  
Group Centroid ◽  
Group Galaxy

AbstractPoor groups are common and interactive environments for galaxies, and thus are important laboratories for studying galaxy evolution. Unfortunately, little is known about groups at z ≥ 0.1, because of the difficulty in identifying them in the first place. Here we present results from our ongoing survey of the environments of strong gravitational lenses, in which we have so far discovered six distant (z ≥ 0.5) groups of galaxies. As in the local Universe, the highest velocity dispersion groups contain a brightest member spatially coincident with the group centroid, whereas lower-dispersion groups tend to have an offset brightest group galaxy. This suggests that higher-dispersion groups are more dynamically relaxed than lower-dispersion groups and that at least some evolved groups exist by z ~ 0.5. We also compare the galaxy and hot gas kinematics with those of similarly distant clusters and of nearby groups.

scholarly journals AGN populations in compact groups of galaxies

2013 ◽  
Vol 9 (S304) ◽  
pp. 337-338
Author(s):  
A. S. Amirkhanian ◽  
A. del Olmo ◽  
A. G. Egikian ◽  
H. Tiersch ◽  
D. Stoll ◽  
...  
Keyword(s):  
Emission Line ◽  
Observational Studies ◽  
Compact Groups ◽  
Broad Line ◽  
Local Universe ◽  
Host Group ◽  
Groups Of Galaxies ◽  
Emission Line Galaxies ◽  
Early Type Galaxy ◽  
Narrow Emission

AbstractCompact groups of galaxies (CGG) have revealed some interesting problems from their origin and lifetime to the evolution of their members in such dense configurations. Some authors suppose that CGG probably are the best location for AGNs in the local Universe. According to our preliminary data about 7–10% of member galaxies in Shahbazian compact groups (SHCGs) are emission-line galaxies including the broad-line AGN and the narrow emission-line galaxies. Shahbazian 355/4 is a classical Seyfert 1 galaxy at the same redshift as host group. Moreover Shahbazian 278/4 is also a broad-line AGN in an early-type galaxy. This is the first emission-line object in SHCGs. Meanwhile there is no Seyfert 1 galaxy among the spectroscopically investigated galaxies in the South compact groups, although more than 70% of the member galaxies in these groups probably have an active nucleus. The UZC- compact groups have an excess of Seyfert 2s (but not Seyfert 1s!). Further observational studies are necessary to understand such and many other questions related to the puzzle of CGG.

scholarly journals COMPACT GROUPS OF GALAXIES WITH COMPLETE SPECTROSCOPIC REDSHIFTS IN THE LOCAL UNIVERSE

2015 ◽  
Vol 48 (6) ◽  
pp. 381-398 ◽  
Author(s):  
JUBEE SOHN ◽  
HO SEONG HWANG ◽  
MARGARET J. GELLER ◽  
ANTONALDO DIAFERIO ◽  
KENNETH J. RINES ◽  
...  
Keyword(s):  
Compact Groups ◽  
Local Universe ◽  
Groups Of Galaxies

scholarly journals The tip-of-the-red-giant-branch distance indicator and the structure of the nearest galaxy groups

2012 ◽  
Vol 8 (S289) ◽  
pp. 240-243
Author(s):  
Lidia Makarova ◽  
Dmitry Makarov
Keyword(s):  
Dwarf Galaxies ◽  
Hubble Space Telescope ◽  
Local Universe ◽  
Distance Determination ◽  
Groups Of Galaxies ◽  
Galaxy Groups ◽  
Magnitude Diagram ◽  
Distance Indicator ◽  
Red Giant ◽  
Distance Indicators

AbstractThe tip of the red giant branch (TRGB) is one of the most accurate distance indicators to galaxies in the Local Universe (for distances up to 8–10 Mpc). A distance accuracy as high as 5% can be achieved with the recently developed maximum-likelihood implementation of the TRGB method and modern calibrations. In this paper, we consider in detail TRGB distance determinations to nearby groups of galaxies (within 8 Mpc). We discuss the photometric accuracy and describe colour–magnitude-diagram features of nearby dwarf galaxies and their influence on the accuracy of distance determination. We have determined accurate structures of the two nearest galaxy groups, M81 and Cen A, using observations of galaxies in these groups with the Hubble Space Telescope's WFPC2 and ACS instruments. The new technique allows us to see new details in the distribution of galaxies in the Canes Venatici i Cloud.

scholarly journals Dynamical Evolution in Hickson Compact Groups using Intragroup Light

2006 ◽  
Vol 2 (S235) ◽  
pp. 199-199
Author(s):  
C. Da Rocha ◽  
B. L. Ziegler ◽  
C. Mendes de Oliveira
Keyword(s):  
Small Groups ◽  
Dynamical Evolution ◽  
Compact Groups ◽  
Evolutionary Sequence ◽  
Efficient Tool ◽  
Local Universe ◽  
Groups Of Galaxies ◽  
Formation And Evolution ◽  
The Mean ◽  
Hickson Compact Groups

AbstractMost of the galaxies in the local universe are located in groups, in particular in small groups, and most of the transformations suffered by galaxies located in today's clusters are likely to have occurred in groups at higher redshifts. Understanding the formation and evolution of groups is essential to understand the whole picture of structures and galaxy build-up. Using multi-band photometry we studied the intragroup light component (IGL) observed in compact groups of galaxies in a subsample of Hickson's catalogue, an efficient tool for determining its stage of dynamical evolution and for mapping its gravitational potential. Applying the OV_WAV package, a wavelet based technique, we can identify the IGL independently of the main contaminating effects. The fractions of IGL detected range from 11% to 46%, with one group with no IGL detected. The colors are consistent with those for old stellar populations and the mean surface brightnesses range from 24.8 to 28.4 B mag arcsec−2. Using the IGL, along with other dynamical evolution indicators, we could establish an evolutionary sequence for our sample.

scholarly journals Large-Scale Flows in the Local Universe

1996 ◽  
Vol 168 ◽  
pp. 175-182 ◽  
Author(s):  
D.S. Mathewson ◽  
V.L. Ford
Keyword(s):  
Large Scale ◽  
Velocity Measurements ◽  
Local Universe ◽  
Peculiar Velocities ◽  
Redshift Surveys ◽  
Density Maps ◽  
The Universe ◽  
Great Wall ◽  
Great Attractor ◽  
Streaming Flow

Peculiar velocity measurements of 2500 southern spiral galaxies show large-scale flows in the direction of the Hydra-Centaurus clusters which fully participate in the flow themselves. The flow is not uniform over this region and seems to be associated with the denser regions which participate in the flow of amplitude about 400km/s. In the less dense regions the flow is small or non-existent. This makes the flow quite asymmetric and inconsistent with that expected from large-scale, parallel streaming flow that includes all galaxies out to 6000km/s as previously thought. The flow cannot be modelled by a Great Attractor at 4300km/s or the Centaurus clusters at 3500km/s. Indeed, from the density maps derived from the redshift surveys of “optical” and IRAS galaxies, it is difficult to see how the mass concentrations can be responsible particularly as they themselves participate in the flow. These results bring into question the generally accepted reason for the peculiar velocities of galaxies that they arise solely as a consequence of infall into the dense regions of the universe. To the N. of the Great Attractor region, the flow increases and shows no sign of diminishing out to the redshift limit of 8000km/s in this direction. We may have detected flow in the nearest section of the Great Wall.

scholarly journals The role of AGN activity in the building up of the BCG at z ∼ 1.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 280-284
Author(s):  
Angela Bongiorno ◽  
Andrea Travascio
Keyword(s):  
Galaxy Cluster ◽  
Cluster Galaxy ◽  
X Ray ◽  
Groups Of Galaxies ◽  
Star Forming ◽  
The Core ◽  
The Galaxy ◽  
Multi Wavelength

AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

scholarly journals DARK MATTER DECAY AND ANNIHILATION IN THE LOCAL UNIVERSE: CLUES FROM FERMI

2010 ◽  
Vol 726 (1) ◽  
pp. L6 ◽  
Author(s):  
A. J. Cuesta ◽  
T. E. Jeltema ◽  
F. Zandanel ◽  
S. Profumo ◽  
F. Prada ◽  
...  
Keyword(s):  
Dark Matter ◽  
Local Universe
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