scholarly journals Using GAMA and H-ATLAS data to explore the cold dust properties of early-type galaxies

2011 ◽  
Vol 7 (S284) ◽  
pp. 262-264
Author(s):  
Nicola K. Agius ◽  
Anne E. Sansom ◽  
Cristina C. Popescu
Keyword(s):  
Galaxy Formation ◽  
Concentration Index ◽  
Elliptical Galaxies ◽  
Host Galaxy ◽  
Early Type ◽  
Large Dataset ◽  
Atlas Data ◽  
Multi Wavelength ◽  
Cold Dust

AbstractHierarchical galaxy formation models predict the development of elliptical galaxies through a combination of the mergers and interactions of smaller galaxies. We are carrying out a study of Early-Type Galaxies (ETGs) using GAMA multi-wavelength and Herschel-ATLAS sub-mm data to understand their intrinsic dust properties. The dust in some ETGs may be a relic of past interactions and mergers of galaxies, or may be produced within the galaxies themselves. With this large dataset we will probe the properties of the dust and its relation to host galaxy properties. This paper presents our criteria for selecting ETGs and explores the usefulness of proxies for their morphology, including optical colour, Sérsic index and Concentration index. We find that a combination of criteria including r band Concentration index, ellipticity and apparent sizes is needed to select a robust sample. Optical and sub-mm parameter diagnostics are examined for the selected ETG sample, and the sub-mm data are fitted with modified Planck functions giving initial estimates for the cold dust temperatures and masses.

scholarly journals Globular Cluster Subpopulations in Early-Type Galaxies: Insights into Galaxy Formation

2002 ◽  
Vol 207 ◽  
pp. 218-228
Author(s):  
Jean P. Brodie
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Morphological Type ◽  
Host Galaxy ◽  
Early Type ◽  
Distant Galaxies ◽  
Nearby Galaxies ◽  
Distant Sample ◽  
Multiple Episodes

New and archival HST images of the globular cluster systems of 17 relatively nearby galaxies and 6 more distant galaxies have been used to establish the characteristics of GC subpopulations over a range of host galaxy morphological type from E5 to Sa. GC color/metallicity, size and luminosity distributions have been examined in the nearby galaxies and color distributions have been determined for the more distant sample. Correlations with parent galaxy properties and trends with galactocentric radius have been explored. Supplemented with Keck spectroscopy, our results are best explained by an in situ formation scenario in which both GC subpopulations formed at early times within the potential well of the protogalaxy, in multiple episodes of star formation. We have also discovered a third population of clusters, fundamentally distinct from the compact red and blue clusters common in early type galaxies.

Constraints on Elliptical Galaxy Formation from Dry Mergers

2006 ◽  
Vol 2 (S235) ◽  
pp. 195-195
Author(s):  
Julia M. Comerford ◽  
Eliot Quataert ◽  
Chung-Pei Ma
Keyword(s):  
Galaxy Formation ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Analytic Model ◽  
Dark Matter Halos ◽  
Early Type ◽  
Mass Assembly ◽  
Minor Mergers ◽  
Analytic Models

Recent observations suggest that dissipationless mergers of elliptical galaxies build up the population of massive early-type galaxies (Bell et al. 2004; Faber et al. 2006). This type of merger is observed in galaxy clusters (Tran et al. 2005) and predicted by semi-analytic models which find mass assembly times significantly later than star-formation times for the most massive elliptical galaxies (de Lucia & Blaizot 2006). Here, we use a semi-analytic model of minor mergers of dark matter halos to examine the role of dry minor mergers in elliptical galaxy formation.

scholarly journals Elliptical Galaxies: Darkly Cloaked or Scantily Clad?

2004 ◽  
Vol 220 ◽  
pp. 165-170
Author(s):  
A. J. Romanowsky ◽  
N. G. Douglas ◽  
K. Kuijken ◽  
M. R. Merrifield ◽  
M. Arnaboldi ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Velocity Dispersion ◽  
Elliptical Galaxies ◽  
Small Sample ◽  
Early Type ◽  
Dynamical Models ◽  
Show Evidence ◽  
Major Merger ◽  
Nearby Galaxies ◽  
Ab Initio Models

Planetary nebulae (PNe) may be the most promising tracers in the halos of early-type galaxies. We have used multi-object spectrographs on the WHT and the VLT, and the new Planetary Nebula Spectrograph on the WHT, to obtain hundreds of PN velocities in a small sample of nearby galaxies. These ellipticals show weak halo rotation, which may be consistent with ab initio models of galaxy formation, but not with more detailed major merger simulations. the galaxies near L* show evidence of a universal declining velocity dispersion profile, and dynamical models indicate the presence of little dark matter within 5 Reff—implying halos either not as massive or not as centrally concentrated as CDM predicts.

scholarly journals The Local Density and Morphology Dependence of the Galaxy Luminosity Function

1987 ◽  
Vol 127 ◽  
pp. 457-457
Author(s):  
Jacek Choloniewski ◽  
Miroslaw Panek
Keyword(s):  
Galaxy Formation ◽  
Luminosity Function ◽  
Local Density ◽  
Elliptical Galaxies ◽  
Low Density ◽  
Early Type ◽  
The Galaxy ◽  
The Moment ◽  
Galaxy Luminosity Function ◽  
Selection Of

We obtained the luminosity function (LF) for samples of galaxies from the CfA North catalogue (Huchra, Davis, Latham and Tonry, 1983). the criteria of selection of samples were the local density (range—more than 2 orders of magnitude) and/or the morphology. No difference in the combined LF for all morphological types is found for subsamples of different density. the LF of elliptical galaxies is found to be less steep at the faint end than the LFs for S and SO galaxies. E galaxies are on the average brighter than the other morphological types. the LFs measured for early–type galaxies (E + S0) in high and low density regions show marginal difference—the low density LF has a steeper faint end slope. (Such a difference is not found for S galaxies). If this feature is maintained for larger samples it may indicate that the LF determined at the moment of galaxy formation is only weakly influenced by the phenomena present in dense regions. This is because these phenomena would rather leave the opposite imprint on the LF—the tidal stripping in dense regions would populate them with faint remnants of disrupted, bright, low angular momentum galaxies. Mergers could not reverse this trend because they act mainly on the bright galaxies.

scholarly journals The Millennium Galaxy Catalogue: Galaxy Bimodality

2006 ◽  
Vol 2 (S235) ◽  
pp. 17-18
Author(s):  
Simon P. Driver ◽  
Jochen Liske ◽  
Alister W. Graham
Keyword(s):  
Galaxy Formation ◽  
Elliptical Galaxies ◽  
Equal Mass ◽  
Early Type ◽  
Rotating Disc ◽  
Compact Structure ◽  
Diffuse Peak ◽  
Structure Plane ◽  
Two Stages ◽  
Two Peaks

AbstractGalaxy bimodality is caused by the bulge-disc nature of galaxies as opposed to two distinct galaxy classes. This is evident in the colour-structure plane which clearly shows that elliptical galaxies (bulge-only) lie in the red compact peak and late-type spiral galaxies (disc-dominated) lie in the blue diffuse peak. Early-type spirals (bulge plus disc systems) sprawl across both peaks. However after bulge-disc decomposition the bulges of early-type spirals lie exclusively in the red compact peak and their discs in the blue diffuse peak (exceptions exist but are rare, e.g., dust reddened edge-on discs and blue pseudo-bulges). Movement between these two peaks is not trivial because whilst switching off star-formation can transform colours from blue to red, modifying the orbits of ~1 billion stars from a planar diffuse structure to a triaxial compact structure is problematic (essentially requiring an equal mass merger). We propose that the most plausible explanation for the dual structure of galaxies is that galaxy formation proceeds in two stages. First an initial collapse phase (forming a centrally concentrated core and black hole), followed by splashback, infall and accretion (forming a planar rotating disc). Dwarf systems coule perhaps follow the same scenario but the lack of low luminosity bulge-disc systems would imply that the two components must rapidly blend to form a single flattened spheroidal system.

scholarly journals Detecting CO at High Redshift

1996 ◽  
Vol 171 ◽  
pp. 151-154
Author(s):  
Linda J. Tacconi
Keyword(s):  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Driving Forces ◽  
High Redshift ◽  
Line Emission ◽  
Host Galaxy ◽  
Molecular Gas ◽  
Ultraluminous Infrared Galaxies ◽  
Star Formation In Galaxies ◽  
Cold Dust

Searches for molecular line emission from high redshift galaxies have become one of the recent highlights in millimeter astronomy, largely because detection of this emission enables one to study the potential for star formation in galaxies at epochs close to galaxy formation. Such information is crucial to models of galaxy evolution. Thus far, most of the searches have been to try to detect any of the rotational lines of CO, although many authors have also inferred the presence of molecular gas through detections of cold dust in the submillimeter region of the spectrum. In addition to providing information about the physical properties of the molecular gas in distant galaxies (when more than one transition or isotope is detected), the CO lines can be used to place stringent constrints on the dynamical masses of these systems. Moreover, since millimeter data has spectral resolutions of typically a few tens of km/s, one can pin down the redshift of the host galaxy with extremely high precision. One of the driving forces in most of the searches for CO emission at high redshift is the fact that molecular gas is known to be an important constituent in the low redshift counterparts to the types of objects that one expects to find at high redshifts, the Ultraluminous Infrared Galaxies (ULIRGs), (e.g. Mirabel and Sanders 1985; Sanders et al. 1986), powerful radio galaxies (e.g. Mazzarella et al. 1993), and nearby quasars (e.g. Barvainis et al. 1989), for example.

scholarly journals BIMA Sub-arcsecond Carbon Monoxide Observations: Resolving the Inner kpc Region of the QSO I Zw 1

2001 ◽  
Vol 205 ◽  
pp. 340-343 ◽  
Author(s):  
Johannes Staguhn ◽  
Eva Schinnerer ◽  
Andreas Eckart
Keyword(s):  
Galaxy Formation ◽  
Angular Resolution ◽  
Line Emission ◽  
Host Galaxy ◽  
Molecular Gas ◽  
Nuclear Region ◽  
Gas Distribution ◽  
Multi Wavelength ◽  
Nearby Galaxies ◽  
Excitation Conditions

We present the first sub-kpc (∼ 0.7 ≈ 0.8 kpc) resolution 12CO(1–0) observations of the ISM in the host galaxy of the QSO I Zw 1 which were obtained with the BIMA mm-interferometer in its A configuration. The measurements, which are part of a multi-wavelength study of I Zw 1, will allow comparison of the ISM properties of a QSO host with those of nearby galaxies and place constraints on galaxy formation/evolution models. Our maps of the 12CO(1–0) line emission from the host galaxy of a QSO show a ring-like structure in the circumnuclear molecular gas distribution with a radius of about 900 pc. The presence of such a molecular gas ring was already predicted from earlier lower angular resolution PdBI observations (Schinnerer, Eckart, & Tacconi 1998). A first comparison of the BIMA data with new PdBI 12CO(2–1) observations with 0.9 angular resolution shows variations in the excitation conditions of the molecular gas in the innermost 3 comprising the nuclear region of I Zw 1.

scholarly journals Early-type galaxy formation history from GALEX-SAURON

2007 ◽  
Vol 3 (S245) ◽  
pp. 193-194
Author(s):  
Hyunjin Jeong ◽  
Sukyoung K. Yi ◽  
Martin Bureau ◽  
Davor Kranović ◽  
Roger L. Davies
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Classical Model ◽  
Stellar Populations ◽  
Elliptical Galaxies ◽  
Early Type ◽  
Secondary Star ◽  
Rich Diversity ◽  
Formation History

One of long-standing debates in modern astrophysics is the formation mechanism of early-type galaxies. The classical model, proposed by Eggel et al. (1962), explains that early-type stellar populations form in an initial highly efficient burst and evolve without further star formation until present day. The high Mg and alpha abundances found in bright elliptical galaxies support such scenarios. Early-type galaxies, therefore, are traditionally believed that they are dynamically simple stellar systems with homogeneous stellar populations (e.g. Gott 1977). The popular Lambda Cold Dark Matter (LCDM) paradigm (e.g. Toomre and Toomre 1972), however, strongly suggested a hierarchical merger picture for massive elliptical galaxies. In this model, early-type galaxies form as a result of major mergers and are thought to have continued star formation. Evidence is growing that a substantial fraction of early-type galaxies has secondary star formation. Furthermore, SAURON survey has revealed a rich diversity in the kinematics, discovering numerous central disks and kinematically decoupled cores (e.g. Emsellem et al. 2004; Sarzi et al. 2006). Early-type galaxies are thus likely to have had complex and varied formation histories.

scholarly journals Shell galaxies as laboratories for testing MOND

2015 ◽  
Vol 93 (2) ◽  
pp. 203-212 ◽  
Author(s):  
M. Bílek ◽  
I. Ebrová ◽  
B. Jungwiert ◽  
L. Jílková ◽  
K. Bartošková
Keyword(s):  
Elliptical Galaxies ◽  
Host Galaxy ◽  
Baryonic Matter ◽  
Line Profiles ◽  
Direct Relation ◽  
Early Type ◽  
Dynamical Friction ◽  
Axially Symmetric ◽  
Matter Distribution ◽  
Gravitational Fields

Tests of MOND in elliptical galaxies are relatively rare because they often lack kinematic tracers in the regions where MOND effects are significant. Stellar shells observed in many elliptical galaxies offer a promising way to constrain their gravitational fields. Shells appear as glowing arcs around the host galaxy, with radii observed up to ∼100 kpc. The stars in axially symmetric shell systems move in nearly radial orbits. The radial distributions of shell locations and the spectra of stars in shells can be used to constrain the gravitational potential of their host galaxy. The symmetrical shell systems, being especially suitable for these studies, occur in approximately 3% of all early-type galaxies. Hence, if we overcome several problems (e.g., multiple shell generations present in the system, shells missed by observations, blurry shell edges, dynamical friction during the merger), the shells substantially increase the number of ellipticals in which MOND can be tested up to large radii. In this paper, we review our work on shell galaxies in MOND. We summarize Bílek et al. (Astron. Astrophys. 559, A110 (2013)), where we demonstrated the consistency of shell radii in an elliptical NGC 3923 with MOND, and Bílek et al. (arXiv:1404.1109. 2014), in which we predicted a giant (∼200 kpc), yet undiscovered shell of NGC 3923. We explain the shell identification method that was used in these two papers. We further describe the expected shape of line profiles in shell spectra in MOND, which is very special because of the direct relation of the gravitational field and baryonic matter distribution (Bílek et al. 2014, in preparation).

scholarly journals The relation between the gas, dust and total mass in edge-on spiral galaxies

2014 ◽  
Vol 10 (S309) ◽  
pp. 297-297
Author(s):  
Flor Allaert
Keyword(s):  
Dark Matter ◽  
Total Mass ◽  
Spiral Galaxies ◽  
3D Structure ◽  
Early Type ◽  
Interstellar Gas ◽  
Data Set ◽  
Unique Role ◽  
Radio Data ◽  
Multi Wavelength

AbstractEach component of a galaxy plays its own unique role in regulating the galaxy's evolution. In order to understand how galaxies form and evolve, it is therefore crucial to study the distribution and properties of each of the various components, and the links between them, both radially and vertically. The latter is only possible in edge-on systems. We present the HEROES project, which aims to investigate the 3D structure of the interstellar gas, dust, stars and dark matter in a sample of 7 massive early-type spiral galaxies based on a multi-wavelength data set including optical, NIR, FIR and radio data.

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