Chain Galaxies Research Articles

Morphologies and Spectral Energy Distributions of Extremely Red Galaxies in the GOODS-South Field

Using U'- through Ks-band imaging data in the Great Observatories Origins Deep Survey-South (GOODS-South) field, we construct a large, complete sample of 275 extremely red objects (EROs; Ks 3.35; AB), all with deep Hubble Space Telescope Advanced Camera for Surveys imaging in B435, V606, i775, and z850 and well-calibrated photometric redshifts. Quantitative concentration and asymmetry measurements fail to separate EROs into distinct morphological classes. We therefore visually classify the morphologies of all EROs into four broad types—early (elliptical-like), late (disk galaxies), irregular, and (chain galaxies and low surface brightness galaxies)—and calculate their relative fractions and comoving space densities. For a broad range of limiting magnitudes and color thresholds, the relative number of early-type EROs is approximately constant at 33%-44%, and the comoving space densities of early- and late-type EROs are comparable. Mean rest-frame spectral energy distributions (SEDs) at λrest ≈ 0.1-1.2 μm are constructed for all EROs. The SEDs are extremely similar in their range of shapes, independent of morphological type. The implication is that any differences between the broadband SEDs of early-type EROs and the other types are relatively subtle, and there is no robust way of photometrically distinguishing between different morphological types with usual optical/near-infrared photometry.

Superwind and Chain Galaxy Formation at High Redshift

We propose a possible new model for the formation of chain galaxies at high redshift.

Gas physics, disk fragmentation, and bulge formation in young galaxies

We investigate the evolution of star-forming gas-rich disks, using a 3D chemodynamical model including a dark halo, stars, and a two-phase interstellar medium with feedback processes from the stars. We show that galaxy evolution proceeds along very different routes depending on whether it is the gas disk or the stellar disk which first becomes unstable, as measured by the respective Q-parameters. This in turn depends on the uncertain efficiency of energy dissipation of the cold cloud component from which stars form. When the cold gas cools efficiently and drives the instability, the galactic disk fragments and forms a number of massive clumps of stars and gas. The clumps spiral to the center of the galaxy in a few dynamical times and merge there to form a central bulge component in a strong starburst. When the kinetic energy of the cold clouds is dissipated at a lower rate, stars form from the gas in a more quiescent mode, and an instability only sets in at later times, when the surface density of the stellar disk has grown sufficiently high. The system then forms a stellar bar, which channels gas into the center, evolves, and forms a bulge whose stars are the result of a more extended star formation history. We investigate the stability of the gas-stellar disks in both regimes, as well as the star formation rates and element enrichment. We study the morphology of the evolving disks, calculating spatially resolved colours from the distribution of stars in age and metallicity, including dust absorption. We then discuss morphological observations such as clumpy structures and chain galaxies at high redshift as possible signatures of fragmenting, gas-rich disks. Finally, we investigate abundance ratio distributions as a means to distinguish the different scenarios of bulge formation.

XMM‐NewtonObservations of the Perseus Cluster. I. The Temperature and Surface Brightness Structure

We present preliminary results of a XMM-Newton 50 ks observation of the Perseus Cluster that provides an unprecedented view of the central 0.5 Mpc region. The projected gas temperature declines smoothly by a factor of 2 from a maximum value of ~ 7 keV in the outer regions to just above 3 keV at the cluster center. Over this same range, the heavy-element abundance rises slowly from 0.4 to 0.5 solar as the radius decreases from 14' to 5', and then it rises to a peak of almost 0.7 solar at 125 before declining to 0.4 at the center. The global east-west asymmetry of the gas temperature and surface brightness distributions, approximately aligned with the chain of bright galaxies, suggests an ongoing merger, although the modest degree of the observed asymmetry certainly excludes a major merger interpretation. The chain of galaxies probably traces the filament along which accretion started some time ago and is continuing at the present time. A cold and dense (low-entropy) cluster core like Perseus is probably well "protected" against the penetration of the gas of infalling groups and poor clusters, whereas in noncooling core clusters such as Coma and A1367, infalling subclusters can penetrate deeply into the core region. In Perseus, gas associated with infalling groups may be stripped completely at the outskirts of the main cluster and only compression waves (shocks) may reach the central regions. We argue, and show supporting simulations, that the passage of such a wave(s) can qualitatively explain the overall horseshoe shaped appearance of the gas temperature map (the hot horseshoe surrounds the colder, low-entropy core) as well as other features of the Perseus Cluster core. These simulations also show that as compression waves traverse the cluster core, they can induce oscillatory motion of the cluster gas that can generate multiple sharp "edges" on opposite sides of the central galaxy. Gas motions induced by mergers may be a natural way to explain the high frequency of "edges" seen in clusters with cooling cores.

Clump Formation in Young Disk Galaxies

We investigate the nature of the clumpy structures seen at high redshift. For this we use a 3D chemodynamical simulation including dark matter, stars and a multiphase interstellar medium as well as feedback processes from the stars. The infall of baryonic matter leads to the formation of a disk which later fragments and develops starforming sub-galactic clumps. Calculating U, B, V, K colors of the model including absorption by interstellar material we find similar morphology and colors as for multiple clump and chain galaxies in the HDF.

The Host Galaxy and Environment of thez = 1.195 Quasar 3C 190

We present deep imaging and spectroscopic observations of the z = 1.195 quasar 3C 190 and its immediate environment. The quasar is surrounded by an asymmetric, low surface brightness envelope in which there are also several galaxies with characteristic dimensions of 3-5 kpc. Some of these form a linear structure some 50 kpc long in projection, offset from the quasar and almost perpendicular to the radio axis. Spectroscopy of this feature indicates the presence of a starburst component, as well as stars a few hundred million years old. Velocities of the emission-line gas associated with H II regions in the linear feature are difficult to reconcile with any reasonable model that is also consistent with the observed morphology. One possible scenario is an edge-on disk in an extremely massive (~1012 M☉) halo; another is two independent chain galaxies, with the apparent alignment being fortuitous. Taking into account all of the types of extended material we find in the vicinity of 3C 190, we appear to be witnessing a relatively brief phase in the development of a spheroidal galaxy, in which merging is proceeding nearly simultaneously in a variety of different regimes. This system may be one of the clearest examples yet found for the mechanism by which many elliptical galaxies and bulges of early-type spirals form in the early universe.

A New Interpretation of Chain Galaxies at High Redshift

We propose a possible new model for the formation of chain galaxies at high redshift. Our model is summarized as follows. (1) Successive merging of subgalactic gas clumps results in the formation of a galaxy with a mass of 1011-1012 M☉ at redshift z ~ 5. (2) Subsequently, supernova explosions occur inside the galaxy and then blow out as a galactic wind (or a superwind). This wind expands into the intergalactic space and then causes a large-scale shell with a radius of several hundred kiloparsecs. Since this radius may be smaller than the typical separation between galaxies, interactions of shells may also occur, resulting in the formation of a large-scale gaseous slab. (3) Since the shell or the slab can be regarded as a gaseous sheet, filament-like gravitational instability is expected to occur. (4) Further gravitational instability occurs in each filament, leading to intense star formation along the filament. This is the chain galaxy phase. (5) The filament collapses gravitationally into one spheroidal system like an elliptical galaxy within one dynamical timescale of the filament (~108 yr). Therefore, it seems quite difficult to find remnants of chain galaxies. We also discuss that shocked shells driven by superwinds may be responsible for some Lyman limit systems and damped Lyα systems because their H I column densities are expected to be N 1019 cm-2.

Far‐Ultraviolet Imagery of the Edge‐on Spiral Galaxy NGC 4631

Far ultraviolet FUV imagery of the edge-on, Sc/SBd galaxy, NGC 4631 reveals very strong FUV emission, resulting from active star formation, uniformly distributed along the galactic mid- plane. Multi-band imagery, HI and HII position-velocity curves and extinction considerations all imply that the emission is from the outer edges of the visible galaxy. The overall FUV morphology of this edge-on disk system is remarkably similar to those of the so-called "chain galaxies" evident at high redshift, thus suggesting a similar interpretation for at least some of those distant objects. FUV, U, B and V magnitudes, measured for 48 star forming regions, along with corresponding H-alpha and H-beta measurements are used to construct diagnostic color-color diagrams. Although there are significant exceptions, most of the star forming regions are less massive and older than 30 Doradus. Comparison with the expectations from two star formation models yields ages of 2.7 to 10 Myr for the instantaneous burst (IB) model and star formation cut-off ages of 0 to 9 Myr for the continuous star formation (CSF) model. Interpreted in terms of the IB model the photometry implies a total created mass in the 48 star forming regions of 25 million solar-masses. When viewed as resulting from constant star formation the photometry implies a star formation rate of 0.33 solar-masses/yr. These results are compared to those derived from FIR and radio observations. Corrections for FUV emission reprocessed by interstellar grains are estimated.

Angular sizes of the faint blue galaxies

We investigate the angular sizes, morphologies and B-1 colours of the 21 :::;; I :::;; 24 galaxies imaged on 10 Wide Field Planetary Camera fields. The number of galaxies with bluer colours (B - 1< 2.0) and moderately large angular sizes exceeds non­ evolving predictions by a factor of ~ 2, but is consistent with pure L * evolution (PLE) models. There is also an excess of galaxies of smaller angular size with very blue B-1 colours, suggesting the presence of a lower redshift starburst dwarf galaxy population, with a steep luminosity function. The bluest (B - I < 1.2) subsample, consisting of 57 galaxies at 21 < 1< 23, contained galaxies with a wide range of angular size and morphology, including spirals, chain galaxies, irregulars and bulge-profile nucleated galaxies. The blue spirals and chain galaxies tend to have the lowest apparent surface brightness, suggesting that they are mostly evolving L * galaxies at higher (z ~ 0.8-2.0) redshifts, while many of the others, with smaller angular sizes, may be starburst dwarf galaxies atz<O.5. At least 16 of these very blue galaxies appear to be interacting, but we find no overall correlation between B-1 colour and the presence of a near neighbour. The angular size distribution of the bluest galaxies is peaked at smaller angular sizes than the PLE model predictions, suggesting that the mean half-light radius of spiral galaxies has increased with time by ~ 25 per cent since z ~ 1.2. Blue galaxies of spiral morphology tend to have larger (by ~ 0.2 dex) half-light radii in the blue band than in the I band, indicating strong radial colour gradients.

The G3 non-isomorphic clustering graph and the problem of the physical reality of the clustering tendency

Chains ofnormal galaxies dominate small-scale clustering. This filamentary structure has nothing to do with large-scale filaments between clusters; and the revelation of short galaxy chains among normal galaxies was not expected by Arp, who investigated chains ofpeculiar galaxies. The nature of revealed chains cannot be explained in terms of so-called filaments observed in a scale of 100 Mpc: there is no continuation between 100 kpc and 100 Mpc chains of galaxies.

Patchy structure and selective extinction

In 1934 Bok argued that the observed phenomenon of clustering of galaxies could not be caused by intergalactic dust matter distributed like the interstellar clouds of dust in the Milky Way. Bok considered background clusters between foreground clusters of galaxies, while Zwicky investigated distant concentrations of galaxies through foreground clusters. Regarding the most distant chains of galaxies observed in the blue band, we investigate the foreground obscuration caused by dust. We indicate the case that galaxies between long chains of galaxies may be considered as obscured by solid grains, familiar of early investigations in statistical astronomy; probably the extinction law is similar to interstellar extinction. We agree with Zwicky's view that intergalactic matter affects the clustering of galaxies: moreover, we extend his research programme to the space between clusters of galaxies. Contrary to half-century tradition, the large clouds of grains similar to the grains occurring in the atmosphere of some stars must be taken as a real factor in the coil of complicated problems connected with the clustering of galaxies.

B2 1141 + 37: a giant radio galaxy with remarkable radio and optical properties

Observations of the giant radio galaxy B2 1141+37, which has a widely separated two-component radio structure and is optically identified with a tight chain of galaxies, are reported. The source was observed at 4900 MHz with the VLA at an effective integration time of 17 min. The map obtained shows two radio lobes with maxima coinciding with those in a previous 1415 MHz map and intensities about 1.5 times smaller than those obtained by extrapolating the spectrum defined by the flux density at 408 and 1415 MHz. Measurements of the redshifts of the two brightest galaxies identified with the radio source with an image intensified dissector scanner result in values of 0.1145 and 0.1155, which imply, with a Hubble constant of 50 km/sec per Mpc, a distance of 687 Mpc to the radio source and a separation of 1.0 Mpc between the lobes making it one of the largest radio sources known.

Markarian's chain of galaxies in Virgo

AbstractOn the basis of a random number generator given by MACLAREN and MARSAGLIA it is demonstrated that MARKARIAN'S chain of galaxies in Virgo is not accidental in its inner structure.

Possible systematic redshifts in a chain of galaxies.

view Abstract Citations (15) References (4) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Possible systematic redshifts in a chain of galaxies. Gregory, S. A. ; Connolly, L. P. Abstract Redshifts are reported for two groups of galaxies. Although these two groups have previously been assigned to the same cluster, their redshifls indicate that they are not associated. A systematic variation of redshifts is found across the chain of one of these groups, Abell 2247, and several interpretations are discussed. Subject headings: galaxies, clusters of - redshifts Publication: The Astrophysical Journal Pub Date: June 1973 DOI: 10.1086/152142 Bibcode: 1973ApJ...182..351G full text sources ADS | data products NED (23) SIMBAD (3)

Chain of galaxies in centaurus

Further photometric and spectroscopic observations of a chain of galaxies in Centaurus are presented and discussed.

On the nature of interacting galaxies

On the nature of interacting galaxies

A Chain of Galaxies.

A Chain of Galaxies.