How the spectral energy distribution and galaxy morphology constrain each other, with application to morphological selection using galaxy colours
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Emir Uzeirbegovic↗
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The Physical Origin of Galaxy Morphologies and Scaling Laws
We propose a numerical study designed to interpret the origin and evolution of galaxy properties revealed by space- and ground-based imaging and spectroscopical surveys. Our aim is to unravel the physical processes responsible for the development of different galaxy morphologies and for the establishment of scaling laws such as the Tully-Fisher relation for spirals and the Fundamental Plane of ellipticals. In particular, we plan to address the following major topics: (1) The morphology and observability of protogalaxies, and in particular the relationship between primordial galaxies and the z approximately 3 'Ly-break' systems identified in the Hubble Deep Field and in ground-based searches; (2) The origin of the disk and spheroidal components in galaxies, the timing and mode of their assembly, the corresponding evolution in galaxy morphologies and its sensitivity to cosmological parameters; (3) The origin and redshift evolution of the scaling laws that link the mass, luminosity size, stellar content, and metal abundances of galaxies of different morphological types. This investigation will use state-of-the-art N-body/gasdynamical codes to provide a spatially resolved description of the galaxy formation process in hierarchically clustering universes. Coupled with population synthesis techniques. our models can be used to provide synthetic 'observations' that can be compared directly with observations of galaxies both nearby and at cosmologically significant distances. This study will thus provide insight into the nature of protogalaxies and into the formation process of galaxies like our own Milky Way. It will also help us to assess the cosmological significance of these observations within the context of hierarchical theories of galaxy formation and will supply a theoretical context within which current and future observations can be interpreted.
Steinmetz, Matthias↗
Comparing Galaxy Morphology at Ultraviolet and Optical Wavelengths
We have undertaken an imaging survey of 34 nearby galaxies in far-ultraviolet (FUV, - 1500A) and optical (UBVRI) passbands to characterize galaxy morphology as a function of wavelength. This sample, which includes a range of classical Hubble types from elliptical to irregular with emphasis on spirals at low inclination angle, provides a valuable database for comparison with images of high-z galaxies whose FUV light is redshifted into the optical and, near-infrared bands. Ultraviolet data are from the UIT Astro-2 mission. We present images and surface brightness profiles for each galaxy, and we discuss the wavelength-dependence of morphology for different Hubble types in the context of understanding high-z objects. In general, the dominance of young stars in the FUV produces the patchy appearance of a morphological type later than that inferred from optical images. Prominent rings and circumnuclear star formation regions are clearly evident in FUV images of spirals, while bulges, bars, and old, red stellar disks are faint to invisible at these short wavelengths. However, the magnitude of the change in apparent morphology ranges from dramatic in early-type spirals with prominent optical bulges to slight in late-type spirals and irregulars, in which young stars dominate both the UV and optical emission. Starburst galaxies with centrally concentrated, symmetric bursts display an apparent "E/SO" structure in the FUV, while starbursts associated with rings or mergers produce a peculiar morphology. We briefly discuss the inadequacy of the optically-defined Hubble sequence to describe FUV galaxy images and estimate morphological k-corrections, and we suggest some directions for future research with this dataset.
Stecher, Theodore↗
Comparing galaxy morphology at ultraviolet and opical wavelengths
We have undertaken an imaging survey of 34 nearby galaxies in far-ultraviolet(FUV, [sim]1500 u and optical (UBVRI) passbands to characterize galaxy morphology as a function of wavelength. This sample, which includes a range of classical Hubble types from elliptical to irregular, with emphasis on spirals at low inclination angle, provides a valuable database for comparison with images of high-z galaxies whose FUV light is redshifted into the optical and near-infrared bands.
galaxies UBVRI imaging morphology star formation s↗
Near-infrared galaxy morphology atlas
We present a representative sample of near-infrared (1-2 mu m) images spanning the Hubble galaxy morphology classification sequence. The images come from the Two Micron All Sky Survey, with a range in brightness of 7 mag , K-s , 13.5 mag, and the morphological classifications from the NASA/IPAC Extragalactic Database.
Hubble sequence dwarf galaxy infrared↗
(abstract) Galaxy Morphology in the Digital Era
A Galaxy Reconstruction Program (GREP) is to be described. Using structural primitives related to galactic structural components, it is demonstrated that realistic galaxy images can be produced. By assigning spectral energy distributions to each of these primitives, the images can be mapped into other wavelengths and thereby viewed at alternate redshifts. This is essentially a method for producing spatially resolved K-corrections for spiral galaxies.
galaxies images spiral galaxies GREP↗
Galaxy Morphology From the UV to the FIR: An Intercomparison of Recent Observations From Space With New Radiative Transfer Models
We will present the latest multiwavelength observations of spiral galaxies made from space and from the ground covering the electromagnetic spectrum from the far ultraviolet (ASTRO-2 UIT observations) through the optical, and out to the far infrared (IRAS). Comparisons with recent theoretical models for the radiative transfer of stellar light through a three-dimensional dusty galaxy will be presented.
Galaxy Morphology↗
Morphology of galaxies in compact groups
Results of a study of galaxy morphology in a homogeneous sample of 98 compact groups of galaxies are reported. Of all the galaxies, 49 percent are of late morphological type (S + Irr), somewhat less than the corresponding fraction for field galaxies. Similarly, for first-ranked galaxies only, 48 percent are late type. Several strong correlations are found between galaxy type and the galaxy environment. Morphological concordance occurs between galaxies within a group. Galaxy morphological type correlates with group optical luminosity, and galaxy morphology correlates with velocity dispersion. The latter correlation is found to be the more fundamental of the two. No strong correlation between morphological type and galaxy space density is found in these compact groups, contrary to the situation in rich clusters and loose groups. These results indicate that the morphological types of galaxies in compact groups are strongly influenced by the environment, and that this influence occurs mostly at the time of galaxy formation.
Hickson, Paul↗
X-ray clusters of galaxies - Correlations with optical morphology and galaxy density
The entire sample of 37 X-ray clusters of galaxies detected by the Ariel 5 satellite at high latitudes is analyzed optically. Morphological types (for all clusters) and central galaxy densities (for all clusters with measured redshifts) are determined, and the positions, redshifts, and richness groups of the set of Southern Hemisphere X-ray clusters are estimated. The X-ray luminosity is found to be correlated with both cluster morphology and central galaxy density. The observed correlations are consistent with a thermal-bremsstrahlung model in which the hot intracluster gas density is proportional to the galaxy density, and the temperature is proportional to the galaxy velocity dispersion.
Bahcall, N. A.↗
The relationships among mass, metallicity, and morphology for spiral galaxies
An evaluation is made of recent results for the gas-phase oxygen abundance of spiral galaxies in order to investigate the relationship between the characteristic abundance of a galaxy and its mass and Hubble type. Conjectures are presented concerning what these relationships may imply for the origin of galaxy morphology.
Zaritsky, Dennis↗
Quantitative Morphology of Galaxies Observed in the Ultraviolet
We present a quantitative study of the far-ultraviolet (FUV) and optical morphology in 32 nearby galaxies and estimate the morphological k-correction expected if these objects were observed unevolved at high redshift.
FUV filters galaxies ultraviolet morphology↗
Multicolor surface photometry of powerful radio galaxies. II - Morphology and stellar content
Results on the morphology, photometric structure, and colors of 72 powerful radio galaxies (PRGs) are presented. It is found that galaxy interactions and mergers play an important role in the PRG phenomenon. Over 50 percent of the sample galaxies display optical morphological deviations from elliptical symmetry at high levels of surface brightness. About 20 percent of the galaxies have a second nucleus less than 10 kpc in projection from the main nucleus. The fraction of PRGs in a common envelope with neighboring galaxies is even larger. Surface brightness profiles for galaxies with weak or no emission lines are typically shallower in slope than normal radio-quiet elliptical galaxies, but similar to the brightest cluster galaxies. Surface brightness profiles for strong emission (SE) galaxies are more diverse in form. The SE PRGs have unusually blue average colors relative to giant elliptical galaxies. These colors are spatially extended and not merely due to light from a bright nucleus or extended emission-line gas.
Smith, Eric P.↗
Statistics of galaxy orientations - Morphology and large-scale structure
Using the Uppsala General Catalog of bright galaxies and the northern and southern maps of the Lick counts of galaxies, statistical evidence of a morphology-orientation effect is found. Major axes of elliptical galaxies are preferentially oriented along the large-scale features of the Lick maps. However, the orientations of the major axes of spiral and lenticular galaxies show no clear signs of significant nonrandom behavior at a level of less than about one-fifth of the effect seen for ellipticals. The angular scale of the detected alignment effect for Uppsala ellipticals extends to at least theta of about 2 deg, which at a redshift of z of about 0.02 corresponds to a linear scale of about 2/h Mpc.
Lambas, Diego G.↗
Morphology of galaxy mergers at intermediate redshift
Using a combination of numerical simulation and synthesized Hubble Space Telescope Wide Field Camera 2 (HST WFC2) images, we follow the detectability of morphological signatures of disk galaxy mergers at intermediate redshifts z = 0.4 and z = 1.0. Rapid evolution in the surface brightness of tidal tails makes their use as an interaction signature limited; long tidal tails will only be detectable relatively early in the encounter, before the galaxies actually merge. Violent relaxation rapidly smooths isophotal irregularities after the galaxies merge, leaving the very low surface brightness tidal debris surrounding the remnant as the only sign of peculiarity after a few hundred Myr. This debris becomes indistinguishable from the main body of the remnant after less than or approximately equal to 0.2 (z = 1.0) to 1 (z = 0.4) Gyr, leaving a morphologically normal elliptical galaxy behind. Using WFC1, all signatures become undetectable almost immediately once the galaxies merge, due to the aberrated Point Speed Function (PSF). We interpret these results in light of recent HST programs investigating the nature of starburst and E + A galaxies in moderate redshift clusters.
Mihos, J. Christopher↗
The morphology-density relation - The group connection
The relationship between galaxy morphology and local density is derived from two complete galaxy redshift surveys. This relationship is completely consistent with the one derived by Dressler for a sample of 55 rich clusters. The apparently universal morphology-density relation extends over six orders of magnitude in galaxy space density. There is no dependence of galaxy morphology on density in regions where the dynamical time scale is comparable with or greater than the Hubble time. At densities greater than about 600 galaxies/cu Mpc, S0's dominate the galaxy population. At these densities, stripping mechanisms are likely to affect the galaxy population. At densities greater than about 3000 galaxies/cu Mpc, the fraction of elliptical galaxies rises steeply. In these regions, the collapse time is short compared with typical time scales for the formation of disks.
Postman, M.↗
Far-infrared luminosity functions of normal galaxies
A volume-limited sample is constructed from the Zwicky catalog and IRAS data base to examine the FIR luminosity functions of normal galaxies, and to investigate possible relationships between FIR emission and galaxy morphology. Quantitative and unbiased treatment is provided by 'survival analysis' statistical methods. It is found that the FIR distributions of normal galaxies are better fit by lognormal than Schechter functions. The total FIR emissivity (8 to 115 microns) of normal galaxies is approximately equal to half their emission in the B plus V optical bands. Normal galaxy FIR emission is uncorrelated with the basic S0-Sm Hubble sequence of spiral galaxy morphology, but appears to be affected by de Vaucouleurs' (1959) revised morphological classifications based on inner rings and S-shaped arms. Spirals with bars and inner rings are systematically fainter than unbarred spirals. It is suggested that bars and rings reduce the amount or spatially confine the dust in spiral disks, resulting in lower efficiency conversion of optical and UV photons into the IR.
Isobe, Takashi↗
The morphological catalogue of galaxies equatorial survey
We present 865 redshifts of galaxies located in the equatorial strip delta between -17.5 deg and -2.5 deg in the right ascension range between 20 h and 5 h. Redshifts have been obtained for the complete sample of all 833 galaxies in the Morphological Catalog of Galaxies with magnitudes brighter than m = 14.5 (corresponding approximately to m(Zwicky) = 15.0). This sample also includes three galaxies from other sources with more reliable magnitudes, satisfying this limit, and 29 fainter galaxies, usually companions of the galaxies in the magnitude limited sample. Our maps of a very large volume of nearby space demonstrate a variety of coherent large scale structures which include large voids, 20-50/h Mpc in diameter and large walls at least 70/h Mpc across.
Huchra, John↗
Studying galaxy cluster morphological metrics with mock-X
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Kaili Cao↗