Shape of the Galactic Orbits in the CNOC1 Clusters
9
Citation
51
Reference
10
Related Paper
Citation Trend
Abstract:
We present an analysis of the orbital properties of nine intermediate-redshift clusters of the Canadian Network for Observational Cosmology (CNOC1) survey and compare them to a control sample of 12 nearby clusters. Similar to the nearby elliptical galaxies, the bulge-dominated galaxies in clusters at redshifts ~0.1-0.4 present orbits that are more eccentric than those of disk-dominated galaxies. However, the orbital segregation is less significant than that found for elliptical and spiral galaxies in nearby clusters. The strongest orbital segregation is found when galaxies are separated by colors [red galaxies with colors in the rest frame (U-V)0 > 1.4, blue galaxies with (U-V)0 ≤ 1.4]. Therefore, the segregation we find seems to modify the star formation activity more efficiently than the internal shape of the galaxies. When we compare the orbits of early-type galaxies at intermediate redshift with those for z = 0, they seem to develop significant changes, becoming much more eccentric. A different behavior is observed in the late-type galaxies, which present no significant evolution in their orbit shapes.Keywords:
Peculiar galaxy
Peculiar galaxy
Cite
Citations (0)
We prepare a catalog of the morphological types of 5840 galaxies within z = 0.01. We determine the morphological types by visual inspection using color images from the Sloan Digital Sky Survey (SDSS) DR7. The majority of the sample galaxies are SDSS spectroscopic target galaxies, but we add ~ 900 galaxies whose redshifts are available in the NASA Extra Galactic Database (NED). The fraction of elliptical and lenticular galaxies is ~ 0.06 while spiral galaxies comprise ~ 30% of the sample with a bar fraction of ~ 0.6. About half of sample are dwarf galaxies of which ~ 35% are dwarf elliptical-like galaxies. There is a strong correlation between the morphological types and luminosities of the galaxies, i.e., high luminosities in the early type galaxies and low luminosity in the late type galaxies. The mean luminosity of dwarf elliptical-like galaxies is similar to that of irregular galaxies.
Peculiar galaxy
Dwarf spheroidal galaxy
Cite
Citations (0)
ABSTRACT Compact groups of galaxies are devised as extreme environments where interactions may drive galaxy evolution. In this work, we analysed whether the luminosities of galaxies inhabiting compact groups differ from those of galaxies in loose galaxy groups. We computed the luminosity functions of galaxy populations inhabiting a new sample of 1412 Hickson-like compact groups of galaxies identified in the Sloan Digital Sky Survey Data Release 16. We observed a characteristic absolute magnitude for galaxies in compact groups brighter than that observed in the field or loose galaxy systems. We also observed a deficiency of faint galaxies in compact groups in comparison with loose systems. Our analysis showed that the brightening is mainly due to galaxies inhabiting the more massive compact groups. In contrast to what is observed in loose systems, where only the luminosities of Red (and Early) galaxies show a dependency with group mass, luminosities of Red and Blue (also Early and Late) galaxies in compact groups are affected similarly as a function of group virial mass. When using Hubble types, we observed that elliptical galaxies in compact groups are the brightest galaxy population, and groups dominated by an elliptical galaxy also display the brightest luminosities in comparison with those dominated by spiral galaxies. Moreover, we show that the general luminosity trends can be reproduced using a mock catalogue obtained from a semi-analytical model of galaxy formation. These results suggest that the inner extreme environment in compact groups prompts a different evolutionary history for their galaxies.
Peculiar galaxy
Cite
Citations (3)
Satellite galaxy
Peculiar galaxy
Cite
Citations (0)
We use the Karachentseva (1973) ``Catalogue of Very Isolated Galaxies'' to investigate a candidate list of >100 very isolated early-type galaxies. Broad-band imaging and low resolution spectroscopy are available for a large fraction of these candidates and result in a sample of 102 very isolated early-type galaxies, including 65 ellipticals and 37 S0 galaxies. Many of these systems are quite luminous and the resulting optical luminosity functions of the Es and early-types (E+S0s) show no statistical differences when compared to luminosity functions dominated by group and cluster galaxies. However, whereas S0s outnumber Es 4:1 in the CfA survey, isolated Es outnumber S0s by nearly 2:1. We conclude that very isolated elliptical galaxies show no evidence for a different formation and/or evolution process compared to Es formed in groups or clusters, but that most S0s are formed by a mechanism (e.g., gas stripping) that occurs only in groups and rich clusters. Our luminosity function results for ellipticals are consistent with very isolated ellipticals being formed by merger events, in which no companions remain. CHANDRA observations were proposed to test specifically the merger hypothesis for isolated ellipticals. However, this program has resulted in the observation of only one isolated early-type galaxy, the S0 KIG 284, which was not detected at a limit well below that expected for a remnant group of galaxies. Therefore, the hypothesis remains untested that very isolated elliptical galaxies are the remains of a compact group of galaxies which completely merged.
Peculiar galaxy
Cite
Citations (29)
Invited Papers: Galaxy Types.- Morphology of Galaxies: An Overview.- The Luminosity Functions of Galaxies.- Elliptical Galaxies.- Structure and Kinematics of Spirals.- Brightest Cluster Members.- Central Regions of Early-Type Galaxies.- Stellar Content and Chemical Evolution in Spheroidal Populations.- Invited Papers: Galaxian Components.- Stellar Disks in Early-Type Galaxies.- Gaseous Disks in Elliptical Galaxies.- Formation and Maintenance of Spiral Structure.- Dark Matter in Elliptical Galaxies.- Dark Matter in Late-Type Galaxies.- Dark Matter in Dwarf Galaxies.- Elliptical Galaxies in X-Rays.- The Warm Component of the ISM of Elliptical Galaxies.- The Bar Component in Disk Galaxies.- Peculiar Kinematics.- Cold Gas in Elliptical Galaxies.- Cold Gas in Late-Type Galaxies.- Abundance Gradients and Related Properties in Galaxies.- Structure and Metallicity of Low-Luminosity Early-Type Galaxies.- Invited Papers: Environment and Systematics.- Interactions: Weak.- Interactions: Strong.- The Morphology of Binary Galaxies.- Intrinsic Shapes of Elliptical Galaxies.- On Understanding the Global Properties of Galaxies.- Galaxy Manifolds and Galaxy Formation.- Sub-Components in Elliptical Galaxies and their Formation.- Morphology and Classification of Galaxies - Where Do We Stand?.- Poster Papers.- Detailed Morphological Classification of Early-Type Galaxies in the Perseus Cluster.- Properties of Dwarf Spheroidals.- Bright Cores in Nearby Southern Galaxies.- Shell Formation and Thick Disks in Elliptical Galaxies.- The Origin of Strong Isophotal Twists in Elliptical Galaxies.- Photometric Properties of Disks in Elliptical Galaxies.- Elliptical Galaxies with Dark Matter.- Nuclear Dust-Discs in Radio Ellipticals.- Extended H? Filaments in Elliptical Galaxies.- The Origin of the Ionized Gas in S0 Galaxies.- Line-Strength Gradients in S0 Galaxies.- Ultraviolet Spectra of Early Type Galaxies.- On the Nature of the Compact Galaxies in the UGC.- Morphology of Galaxies Surrounding Compact Groups.- Mean Surface Density and Morphological Type in Disc-Galaxies.- Peculiar Kinematics in Interacting Elliptical Galaxies.- Morphology and Kinematics of Spiral Galaxies without Bar: The Importance of the Central Mass.- The Correlation between Velocity Gradients and Arm Classification in Spiral Galaxies.- Optical Line/Radio Luminosity Correlation and the Effects of the Interstellar Medium.- The Luminosity-Diameter Relation for Disk Galaxies: A Search for Environmental Effects.- Global Properties in Early Type Galaxies.- Masses and Mass-to-Light Ratios of Elliptical Galaxies.- On the Photometric Scaling Laws for Early-Type Galaxies.- Properties of Brightest Cluster Members.- The Fundamental Plane for Early-Type Galaxies.- Elliptical Galaxies and the Thickness of the Fundamental Plane.- Dissipationless Formation of Elliptical Galaxies.- The Two-Component Colour-Structure of the gE Galaxy NGC 4472.- The Velocity Dispersion Anisotropy in NGC 720.- NGC 205 and the Nature of Compact Nuclei in Dwarf Galaxies.- Light and Color Distribution in the Core of M32.- NGC 3384 and Its Saturn-Like Appearance.- Cigale Observations of NGC 3198.- Mapping the Star Formation in Nearby Galaxies: The Magellanic Irregular NGC 3109.- MM Observations of the Magellanic Clouds from Antarctica.- Seyfert Galaxies with Close Companions. A Method for Identification.- Globular Clusters as Probes of the Galactic Potential.- Relation between the Properties of Globular Cluster System and the Mass Distribution on the Galactic Disk.- Towards a Precise Definition of the Morphological Structures of Galaxies as a Basis for Their Automatic Classification.- Fourier Analysis of Barred Galaxies: A Convenient Alternative to the Component Decomposition.- Improvements of the Signal-to-Noise Ratio by Adaptive Filtering.- Index of Objects.
Peculiar galaxy
Dwarf spheroidal galaxy
Cite
Citations (2)
The data collected in the Shapley–Ames catalog of bright galaxies show that lenticular (S0) galaxies are typically about a magnitude fainter than both elliptical (E) and early spiral (Sa) galaxies. Hubble was therefore wrong to regard S0 galaxies as being intermediate between morphological types E and Sa. The observation that E5–E7 galaxies are significantly fainter than objects of subtypes E0–E5 suggests that many of the flattest "ellipticals" may actually be misclassified lenticular galaxies. In particular, it is tentatively suggested all E7 galaxies might actually be misclassified S01(7) galaxies. The present results are consistent with the view that galaxies belonging to the S0 class evolved in environments in which they typically lost more than half of their original luminous material.
Peculiar galaxy
Cite
Citations (30)
H II galaxies are dwarf star forming galaxies found in objective prism surveys through their strong emission lines. They have been targets of extensive studies of their spectroscopic properties such as chemical abundances, physical conditions and kinematics. Little surface photometry work has been done on H II galaxies up to now. This thesis is primarily a CCD surface photometry study of the structural properties, optical colors and a statistical analysis of the environment of H II galaxies. In the chapter "The Morphology of H II Galaxies" I have used a sample of 39 H II galaxies with CCD images for a study of their overall morphology and luminosity profiles. The results show that H II galaxies can be classified in two main types: type I H II galaxies are luminous and have disturbed and irregular outer shapes while type II H II galaxies are less luminous and have regular shapes. The outer parts of profiles of all HIi galaxies are well represented by an exponential as in other types of known dwarf galaxies. In "The Dynamics of H II Galaxies" I have investigated the relation between the linear size of the starburst, luminosity and velocity dispersion. It is found that H II galaxies have similar relations as virialized systems which supports the gravitational origin of their overall kinematics. The possible bi-parametric behavior ("fundamental plane") of H II galaxies is also investigated. However, a conclusive answer to this question still requires more and better data. In "The Colors of H II Galaxies" I have presented a high spatial resolution CCD surface photometry study. The colors of the underlying stellar continuum within the starburst are obtained by removing the flux contribution of the emission lines in the broad band filters. Comparison with recent evolutionary population synthesis models show that the observational errors and the uncertainties in the models are still too large to put strict constraints on their past star formation history. However, the distribution of colors of the underlying galaxy in H II galaxies is similar to the colors of some dwarf galaxies which suggests a kinship of these with the quiescent phases of H II galaxies. In "The Environment of H II Galaxies" I have studied the environment of 51 H II galaxies for which I have CCD images, H-beta luminosity, velocity dispersion, H-beta equivalent width and oxygen abundance. The aim of the study is to check the tidal origin of the starburst in H II galaxies and the effect of the environment on their intrinsic properties. It is found that only 12 H II galaxies have a bright neighbour within a projected distance of 1 Mpc and 250 km s-1 in velocity difference. Surprisingly, isolated H II galaxies tend to be of high luminosity and disturbed morphology while H II galaxies with neighbours tend to be low luminosity regular H II galaxies. Furthermore, the metal abundance and the equivalent width of the emission lines in H II galaxies do not depend on the presence of a companion. These results are opposed to what is expected if interaction with a luminous companion is the main mechanism triggering the starbursts. It is also found a loose group of four H II galaxies with no luminous companion. For this, there is the additional difficulty of understanding how these starbursts are synchronized on time scales of less than 107 yrs in systems separated by ~1-2 Mpc.
Peculiar galaxy
Surface brightness fluctuation
Cite
Citations (2)
We report the analysis of HST WFPC2 F606W images of a sample of 35 spiral galaxies. We describe the optical morphological properties of the galaxies on scales of a few tens of parsecs, derive the surface brightness profiles for 18 of them, and present the results of analytical fits to these profiles. We find that: (I) Several galaxies, despite their classification as relatively early spirals, show little or no morphological evidence for a smooth, featureless (i.e., classical) bulge. Furthermore, even in the classical bulges, nuclear dust lanes are detected, similar to what is observed in early-type galaxies. (11) In several cases spiral structure reaches down to the innermost accessible scales. (III) A central, bright component is often identified. However, this does not resemble a classical bulge but has instead a highly irregular morphology. (IV) Bright knots, very likely star forming regions, are often present within the inner galactic regions in these irregular bulges. In several other cases, nuclear star formation is observed, but it is unclear whether this is associated with a small irregular bulge or with the inner disk. (V) Resolved, central compact sources are found in 18 of the 35 galaxies, including several early-type spirals. In two objects, NGC 1483 and NGC 3259, the central source is unresolved. Within the errors and the limited statistics, the central compact source luminosity seems independent of Rubble type, but correlates with the luminosity, of the disk galaxy. (VI) The central compact sources in star forming galaxies are typically brighter, for similar radii, than those in non star forming galaxies. (VII) The brightest compact sources have properties similar to those of young star clusters in the absolute magnitude (MV) versus half-light radius (Re) plane. The faintest compact sources are bracketed, in the MV-Re plane, between Kormendy's fit to elliptical galaxies and the correlation defined by classical R1/4 bulges and Galactic globular clusters. The latter implies a roughly constant mean surface brightness within the effective radius. Therefore, the luminosity sequence of the compact sources might represent an age sequence of superluminous star clusters in the centers of disk galaxies. The widespread presence of star formation in the irregular bulges, the irregular bulges themselves, and the presence of superluminous star clusters in the nuclei of spirals, support scenarios in which a fraction of bulges forms relatively late, in dissipative accretion events driven by the disk.
Peculiar galaxy
Cite
Citations (185)
We have derived the X-ray luminosities of a sample of galaxies in groups, making careful allowance for contaminating intragroup emission. The LX:LB and LX:LFIR relations of spiral galaxies in groups appear to be indistinguishable from those in other environments, however the elliptical galaxies fall into two distinct classes. The first class is central-dominant group galaxies, which are very X-ray luminous and may be the focus of group cooling flows. All other early-type galaxies in groups belong to the second class, which populates an almost constant band of LX/LB over the range 9.8< log LB<11.3. The X-ray emission from these galaxies can be explained by a superposition of discrete galactic X-ray sources together with a contribution from hot gas lost by stars, which varies a great deal from galaxy to galaxy. In the region where the optical luminosity of the non-central group galaxies overlaps with the dominant galaxies, the dominant galaxies are over an order of magnitude more luminous in X-rays. We also compared these group galaxies with a sample of isolated early-type galaxies, and used previously published work to derive LX:LB relations as a function of environment. The non-dominant group galaxies have mean LX/LB ratios very similar to those of isolated galaxies, and we see no significant correlation between LX/LB and environment. We suggest that previous findings of a steep LX:LB relation for early-type galaxies result largely from the inclusion of group-dominant galaxies in samples.
Peculiar galaxy
Cite
Citations (53)