bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Diffraction Based Analysis of Phase Fractions and Texture in Nanocrystalline Thin Films, Part I: Principles
Authors: Lábár János L.
Published: July 2008

A method for phase analysis, similar to the Rietveld method in X-ray diffraction, was not developed for electron diffraction (ED) in the transmission electron microscope (TEM), mainly due to the dynamic nature of ED. Nowadays, TEM laboratories encounter many thin samples with grain size in the 1–30 nm range, not too far from the kinematic ED conditions. This article describes a method that performs (semi)quantitative phase analysis for nanocrystalline samples from selected area electron diffraction (SAED) patterns. Fractions of the different nanocrystalline components are determined from rotationally symmetric ring patters. Both randomly oriented nanopowders and textured nanopowders, observed from the direction of the texture axis produce such SAED patterns. The textured fraction is determined as a separate component by fitting the spectral components, calculated for the previously identified phases witha prioriknown structures, to the measured distribution. The Blackman correction is applied to the set of kinematic diffraction lines to take into account dynamic effects for medium grain size. Parameters of the peak shapes and the other experimental parameters are refined by exploring the parameter space with the help of the Downhill-SIMPLEX. Part I presents the principles, while future publication of Parts II and III will elaborate on current implementation and will demonstrate its usage by examples, respectively.
Electron Digital Imaging toward High-Resolution Structure Analysis of Biological Macromolecules
Authors: Maki-Yonekura Saori , Yonekura Koji
Published: July 2008

Digital imaging has been applied to structure analysis of biological macromolecules in combination with electron energy filtering. Energy filtering can improve the image contrast of frozen-hydrated specimens, but needs a high-sensitivity imaging device instead of photographic film, because of a decrease in electrons after filtration. Here, a lens-coupled slow-scan charge-coupled device (SSCCD) camera with a post-column-type energy filter were examined to image bacterial flagellar filaments embedded in ice. We first measured the modulation transfer function of this camera and showed the remarkable improvement, compared to other fiber-coupled SSCCD cameras. The 3D structure calculated at ∼7-Å resolution clearly resolves α-helices. Furthermore, filtered datasets recorded on the SSCCD camera with liquid-nitrogen and liquid-helium cooling were compared with the previous unfiltered one on film with liquid-helium cooling. This report describes the suitability of digital imaging with energy filtering for higher-resolution structure studies from its practical application.
Estimation of the Reconstruction Parameters for Atom Probe Tomography
Authors: Gault Baptiste , de Geuser Frederic , Stephenson Leigh T. , Moody Michael P. , Muddle Barrington C. , Ringer Simon P.
Published: July 2008

The application of wide field-of-view detection systems to atom probe experiments emphasizes the importance of careful parameter selection in the tomographic reconstruction of the analyzed volume, as the sensitivity to errors rises steeply with increases in analysis dimensions. In this article, a self-consistent method is presented for the systematic determination of the main reconstruction parameters. In the proposed approach, the compression factor and the field factor are determined using geometrical projections from the desorption images. A three-dimensional Fourier transform is then applied to a series of reconstructions, and after comparing to the known material crystallography, the efficiency of the detector is estimated. The final results demonstrate a significant improvement in the accuracy of the reconstructed volumes.
Challenges for maintaining sustainable agricultural systems in the United States
Authors: Hanson J.D. , Hendrickson John , Archer Dave
Published: July 2008

During the 20th century, US agriculture underwent vast transformations. The number of farmers has decreased, more farmers are relying on off-farm income, agriculture's proportion of the US GDP has declined, and a minority of non-metro counties in the US are farming dependent. Agriculture's evolution will continue and we have identified key trends and future challenges to effectively manage our changing agricultural system. Eight current trends in US agriculture were identified. These included: (1) increased land degradation; (2) competing land uses; (3) focus on single ecosystem service; (4) increase in farm size; (5) movement toward commercialization; (6) genetic engineering; (7) global markets; and (8) changing social structure. Future trends likely to affect agriculture include: (1) diminishing and increasingly volatile farm incomes; (2) reduced government involvement in food regulation; (3) continued transition from farming to agribusiness; (4) land-use will become a major issue; (5) increasing animal protein consumption in the US; (6) increased public input on livestock production practices; (7) increasing urbanization of historically rural US counties; (8) increased public concern over food safety; (9) increased medicinal production from agriculture; (10) new tastes, markets and opportunities will emerge. We further postulated that future challenges facing US agriculture might include: (1) competitive pressures; (2) sustainable development; (3) resource conservation; and (4) research and development. Integrated agricultural systems may be flexible enough to address these challenges. However, robust principles will be needed to design adaptable integrated agricultural systems. We present a nonexclusive list of preliminary principles under the four general categories of (1) economics and economic policies; (2) environmental; (3) social and political; and (4) technological.
Interactions in integrated US agricultural systems: The past, present and future
Authors: Hendrickson J. , Sassenrath G.F. , Archer D. , Hanson J. , Halloran J.
Published: July 2008

During the 20th century, American agriculture underwent dramatic changes. At the beginning, farms were more diverse, dependent on animal traction, on-farm inputs and income and, after initial land grants, nearly independent of government policy. However, external issues, such as government policies, mechanization, fossil fuel costs, increased consolidation and vertical integration of markets and increased societal awareness of the environment and concern with farming practices, have substantially altered the structure of agriculture. These external issues are significant drivers of agriculture and we grouped them into social/political, economic, environmental and technological drivers. Previous papers have examined specific effects of these drivers. Our objective is to examine how these drivers interact and influence today's agricultural systems. We developed four categories: (1) Commodity Crop Production, (2) Supply Chain Livestock Production, (3) Organic Production and (4) Extensive Livestock Production, to describe major current agricultural systems. These categories were developed as major and contrasting systems but do not represent all of American agriculture. Although it is not possible to predict the future, interactions among the various drivers will affect these systems differently. By examining multiple scenarios, we conclude the highly specialized systems (Nos. 1 and 2) are highly vulnerable to future changes, and that developing adaptive capacity is critical for dealing with new uncertainty. Sustainable agricultural systems will need balance among various domains to be able to adapt and survive. We suggest that the concept of dynamic-integrated agricultural systems may be the best way to meet this goal because of its ability to consider multiple goals and flexible producer decision-making.
Adding value in the organic sector: Characteristics of organic producer–handlers
Authors: Oberholtzer Lydia , Dimitri Carolyn , Greene Catherine
Published: July 2008

Sales of organic food have soared over the past decade. Although nearly all organic commodities pass through the hands of at least one intermediary on the way from the farmer to the consumer, there is a dearth of literature examining organic food marketing, especially for the middle section of the supply chain. This paper uses new survey data on organic intermediaries (organic handlers) to characterize firms that are certified to both handle and produce organic foods, or organic producer–handlers. Because of their direct link to the production level, the producer–handler has the potential to provide insight into value-added activities in the organic sector. A logistic regression is estimated in order to identify characteristics that make it more likely that a firm would be both a certified organic handler and a certified organic producer, while survey results are also used to describe some of the main challenges these producer–handlers face in handling their products. Organic producer–handlers ranked problems with ingredient procurement and supply and international trade issues as the highest barriers to growth. The model indicated that with few exceptions, many of the operational and procurement characteristics of organic producer–handlers are comparable to the entire organic handling population. However, those facilities dedicated solely to organic handling and those certified longer are more likely to be organic producer–handlers. Use of direct markets by organic handlers has the most robust relationship in the model, although marketing to natural products independent retailers and wholesalers are also important.
Galactic bulges: overview
Authors: Freeman K. C.
Published: July 2008

This overview of galactic bulges begins with a discussion of the various kinds of bulges (classical, boxy/peanut-shaped, pseudo) and their likely formation mechanisms. Other specific topics include the Galactic bar/bulge and its chemical evolution, the bulge of M31, the relation between bulges and metal-poor halos (often lumped together as spheroids), the morphology-density relation and the formation of S0 galaxies, the color-structure bimodality, and scaling laws for bulges. Finally I will briefly discuss the current difficulty of forming bulgeless disk galaxies in ΛCDM.
Fast and slow rotators: the build-up of the red sequence
Authors: Emsellem Eric , Cappellari Michele , Krajnović Davor , van de Ven Glenn , Bacon R. , Bureau M. , Davies Roger L. , de Zeeuw P. T. , Falcón-Barroso Jesús , Kuntschner Harald , McDermid Richard M. , Peletier Reynier F. , Sarzi Marc , van den Bosch Remco C. E.
Published: July 2008

Using the unique dataset obtained within the course of theSAURONproject, a radically new view of the structure, dynamics and stellar populations of early-type galaxies has emerged. We show that galaxies come in two broad flavours (slow and fast rotators), depending on whether or not they exhibit clear large-scale rotation, as indicated via a robust measure of the specific angular momentum of baryons. This property is also linked with other physical characteristics of early-type galaxies, such as: the presence of dynamically decoupled cores, orbital structure and anisotropy, stellar populations and dark matter content. I here report on the observed link between this baryonic angular momentum and a mass sequence, and how this uniquely relates to the building of the red sequence via dissipative/dissipationless mergers and secular evolution.
Constraining the internal dynamics of stellar systems using the NMAGIC particle code
Authors: De Lorenzi Flavio , Gerhard Ortwin , Debattista Victor P. , Sambhus Niranjan , Coccato L. , Arnaboldi M. , Capaccioli M. , Douglas N. G. , Freeman K. C. , Kuijken K. , Merrifield M. R. , Napolitano N. R. , Noordermeer E. , Romanowsky A. J.
Published: July 2008

NMAGIC is a parallel implementation of our made-to-measure (χ2M2M) algorithm for constructing N-particle models of stellar systems from observational data, which extends earlier ideas by Syer & Tremaine (1996). The χ2M2M algorithm properly accounts for observational errors, is flexible, and can be applied to various systems and geometries. We show its ability to reproduce the internal dynamics of an oblate isotropic rotator model and report on the modeling of the dark matter (DM) halo of NGC 3379 combining SAURON and PN.S kinematic data. The χ2M2M algorithm is practical, reliable and can be applied to various dynamical systems without symmetry restrictions. We conclude that χ2M2M holds great promise for unraveling the internal dynamics of bulges.
The role of stellar feedback in the formation of galactic disks and bulges in a ΛCDM Universe
Authors: Ceverino Daniel , Klypin Anatoly
Published: July 2008

Although supernova explosions and stellar winds happens at scales bellow 100 pc, they affect the interstellar medium (ISM) and galaxy formation. We use cosmological N-body+Hydrodynamics simulations of galaxy formation, as well as simulations of the ISM to study the effect of stellar feedback on galactic scales. Stellar feedback maintains gas with temperatures above a million degrees. This gas fills bubbles, super-bubbles and chimneys. Our model of feedback, in which 10%–30% of the feedback energy is coming from runaway stars, reproduces this hot gas only if the resolution is better than 50 pc. This is 10 times better than the typical resolution in cosmological simulations of galaxy formation. Only with this resolution, the effect of stellar feedback in galaxy formation is resolved without any assumption about sub-resolution physics. Stellar feedback can regulate the formation of bulges and can shape the inner parts of the rotation curve.
A new 3D potential-density basis set
Authors: Rahmati Alireza , Jalali Mir Abbas
Published: July 2008

A set of bi-orthogonal potential-density basis functions is introduced to model the density and its associated gravitational field of three dimensional stellar systems. Radial components of our basis functions are weighted integral forms of spherical Bessel functions. We discuss on the properties of our basis functions and demonstrate their shapes for the latitudinal Fourier numberl= 2.
Elucidation of kinematical and dynamical structure of the Galactic bulge
Authors: Yano T. , Gouda N. , Ueda H. , Koyama H. , Kan-ya Y. , Taruya A.
Published: July 2008

Future space mission of astrometric satellite, GAIA and JASMINE (Japan Astrometry Satellite Mission for Infrared Exploration), will produce astrometric parameter, such as positions, parallaxes, and proper motions of stars in the Galactic bulge. Then kinematical information will be obtained in the future. Accordingly it is expected that our understanding of the dynamical structure will be greatly improved. Therefore it is important to make a method to construct a kinematical and dynamical structure of the Galactic bulge immediately.
Formation and evolution of galactic spheroids by mergers
Authors: Naab Thorsten , Burkert Andreas , Johansson Peter H. , Jesseit Roland
Published: July 2008

Galactic spheroids can form as a result of galaxy interactions and mergers of disks. Detailed analyses of the photometric properties, the intrinsic orbital structure, the line-of-sight velocity distributions and the kinemetry of simulated merger remnants, which depend critically on the geometry and the gas content of the interacting progenitors, indicate that low and intermediate mass rotating ellipticals can form from mergers of disks. The masses and metallicities of all massive ellipticals and the kinematics of some massive non-rotating ellipticals cannot be explained by binary mergers. Thus these galaxies might have formed in a different way.
How galaxies gain and lose their angular momentum
Authors: D'Onghia Elena
Published: July 2008

Spiral, fast-rotating galaxies like the Milky Way are the most common type in the Universe. One of the most pressing challenges faced by current models of galaxy formation is the origin of their angular momentum and disk. According to the standard tidal-torque theory the galactic spin is originated by tidal interactions between dark halos around galaxies and neighboring structures in the expanding Universe. We use a large cosmological N-body simulation to study the origin of possible correlations between the merging history and spin of cold dark matter halos. In particular, we examine claims that remnants of major mergers tend to have higher-than-average spins, and find that the effect is driven largely by unrelaxed systems: equilibrium dark matter halos show no significant correlation between spin and merging history. Out-of-equilibrium halos have, on average, higher spin than relaxed systems, suggesting that the virialization process leads to a net decrease in the value of the spin parameter. We present also high-resolution N-body/SPH cosmological simulations including cold gas and dark matter to investigate the processes by which gas loses its angular momentum during the protogalactic collapse phase, leading to simulated disk galaxies that are too compact with respect to the observations. We show that the gas and the dark matter have similar specific angular momenta until a merger event occurs at redshift 2. All the gas involved in the merger loses a substantial fraction of its specific angular momentum due to tidal torques and falls quickly into the center. Dynamical friction by small infalling substructures plays a minor role, in contrast to previous claims.
The hierarchical build-up of bulges in CDM
Authors: Khochfar Sadegh
Published: July 2008

We investigate the hierarchical build-up of stars in bulges within the standard Λ-cold dark matter scenario. By separating the population into stars born during starbursts that accompany the formation of spheroids in major mergers (starburst component), and stars that are previously formed in discs of progenitor galaxies (quiescent component) and added to the spheroid by dynamical interaction. Our results are summarised as follows: bulges that form early have larger starburst fraction and hence should be smaller than their counter parts that form later. The quiescent fraction in bulges is an increasing function of bulge mass, becoming constant at Mq/Mbul ~ 0.8, mainly due to the infall of satellite galaxies that contribute disc stars to the bulge. Minor mergers are an order of magnitude more frequent than major mergers and must play a significant role in the evolution of bulges. Above the critical mass Mc ~ 3 × 1010 M⊙ most of the stars in the universe are in spheroids, which at high redshift are exclusively elliptical galaxies and at low redshifts partly bulges. Due to the enhanced evolution of galaxies ending up in high density environments, the starburst fraction and the surface mass densities of bulges below Mc should be enhanced with respect to field galaxies. Dissipation during the formation of massive bulges in present day early-type spirals is less important than for the formation of present day elliptical galaxies of the same mass thereby explaining the possible difference in phase-space densities between spiral galaxies and elliptical galaxies.
Forming bulges during galaxy minor mergers
Authors: Cox T. J. , Younger J. , Hernquist L. , Hopkins P. F.
Published: July 2008

The hierarchical formation of structure suggests that dark halos, and the galaxies they host, are shaped by their merging history. While the idea that mergers between galaxies of equal mass, i.e., major merger, produce elliptical galaxies has received considerable attention, he galaxies that result from minor merger, i.e., mergers between galaxies with a large mass ratio, is much less understood. We have performed a large number of numerical simulations of minor mergers, including cooling, star formation, and black hole growth in order to study this process in more detail. This talk will present some preliminary results of this study, and in particular, the morphology and kinematics of minor merger remnants.
Bulges vs elliptical galaxies: some clues from their formation in a cosmological context
Authors: Domínguez-Tenreiro R. , Martínez-Serrano F. J. , Serna A. , Mollá M. , Oñorbe J.
Published: July 2008

We report on an extension, through cosmological simulations, of the two-phase formation scenario for elliptical galaxies to classical spiral bulges. In particular, we analyze the possibility that the old stellar population of bulges forms in a fast phase, while the younger stellar component forms or is assembled in a slow phase, in part from disk material suffering instabilities and in part through satellite capture or mergers.
Compact elliptical galaxies – compact bulges of stripped lenticulars/spirals?
Authors: Chilingarian Igor , Cayatte Veronique , Chemin Laurent , Durret Florence
Published: July 2008

We present discovery of compact elliptical galaxies in the centres of clusters and briefly discuss their evolution.
Lopsidedness and sloshing in centres of advanced mergers of galaxies
Authors: Jog Chanda J. , Maybhate Aparna
Published: July 2008

We measure the non-axisymmetry in the luminosity distribution in the central few kpc of a sample of advanced mergers of galaxies, by analyzing their 2MASS images. All mergers show a high central asymmetry: the centres of isophotes show a striking sloshing pattern with a spatial variation of upto 30% within the central 1 kpc; and the Fourier amplitude for lopsidedness (m = 1) shows high values upto 0.2 within the central 5 kpc. The central asymmetry is estimated to be long-lived, lasting for ~ a few Gyr or ~ 100 local dynamical timescales. This will significantly affect the dynamical evolution of this region, by helping fuel the central active galactic nucleus, and also by causing the secular growth of the bulge driven by lopsidedness.
Star formation history and isophotal shapes of fossil central galaxies
Authors: Khosroshahi Habib G. , Nolan Louisa A.
Published: July 2008

We study the structure and stellar populations of the luminous elliptical galaxies dominating fossil groups and compare them with the brightest galaxies in ordinary groups. Despite being over-luminous, the fossil central galaxies do not show boxy stellar isophotes which are usually associated with luminous elliptical galaxies. Boxy isophotes, according to the numerical simulations, are produced in gas poor mergers. The isophotal shapes of the fossil central galaxies, therefore, suggest a gas rich merger for fossil central galaxies. Using a two-component spectral fitting, we show that the dominant stellar population of the fossil and non-fossil galaxies is old and the second population is either old or intermediate age. However, the second stellar component (recently-formed stars) in fossil central galaxies is significantly more metal poor than that in the brightest galaxies of non-fossil groups.
Variations in the 24 μm morphologies of nearby galaxies
Authors: Bendo G. J.
Published: July 2008

To study the distribution of star formation and dust emission within nearby galaxies, we measured five morphological parameters in the 24 μm wave band for 73 galaxies observed as part of the Spitzer Infrared Nearby Galaxies Survey. The morphological parameters demonstrate strong variations along the Hubble sequence, including statistically significant differences between S0/a-Sab and Sc-Sd galaxies. Early-type spiral galaxies are generally found to be compact, centralized, symmetric sources in the 24 μm band, whereas late-type spiral galaxies are generally found to be extended, asymmetric 24 μm sources. These results suggest that processes that increase the real or apparent sizes of galaxies' bulges also lead to more centralized 24 μm emission.
Bulge properties and dark matter content of early-type barred galaxies
Authors: Corsini E. M.
Published: July 2008

The dynamics of a barred galaxy depends on the pattern speed of its bar. The only direct method for measuring the pattern speed of a bar is the Tremaine-Weinberg technique. This method is best suited to the analysis of the distribution and dynamics of the stellar component. Therefore it has been mostly used for early-type barred galaxies. Most of them host a classical bulge. On the other hand, a variety of indirect methods, which are based on the analysis of the distribution and dynamics of the gaseous component, has been used to measure the bar pattern speed in late-type barred galaxies. Nearly all the measured bars are as rapidly rotating as they can be. By comparing this result with high-resolution numerical simulations of bars in dark matter halos, it is possible to conclude that these bars reside in maximal disks.
Bar strengths in early-type disk galaxies
Authors: Buta R. , Laurikainen E. , Salo H. , Knapen J. H. , Block D. L.
Published: July 2008

Using the gravitational torque indicator Qb, we derive the distribution of bar strengths for a sample of early-type disk galaxies. The sample is part of the Near-Infrared S0 Survey (NIRS0S), designed to examine the properties of bars, bulges, and disks in galaxies classified as types S0− to Sa. Although the survey is only partly finished, we find that the distribution of bar strengths in S0 galaxies differs from that in spirals by lacking an extended tail to high values of Qb. No S0 in our current sample has Qb > 0.25, while spirals extend to Qb ≈ 0.7. Bars having Qb > 0.25 first appear among S0/a to Sa galaxies.
Kinematics and stellar populations of the double-barred early-type galaxy NGC357
Authors: de Lorenzo-Cáceres Adriana , Vazdekis Alexandre , Aguerri J. Alfonso L.
Published: July 2008

We have carried out a kinematical and stellar population analysis of the double-barred galaxy NGC357 to provide a more complete characterization of these systems and their role in the formation of galaxy bulges. We clearly identify the presence of the inner bar in the radial velocity and velocity dispersion profiles. The age, metallicity and [Mg/Fe] abundance ratio estimates are very similar to those of ellipticals of equivalent central σ. The [Mg/Fe] value for the bulge of this galaxy suggests formation timescales shorter than 1Gyr.
The intrinsic equatorial ellipticity of bulges
Authors: Méndez-Abreu J. , Aguerri J. A. L. , Corsini E. M. , Simonneau E.
Published: July 2008

Traditionally, the study of the structural parameters of galaxies have been used to understand the bulge formation processes. However, one piece lost in this study is the three-dimensional shape of the bulges. In this work, the structural parameters of a magnitude-limited sample of 148 unbarred S0-Sb galaxies were derived to study the correlations between bulge and disk parameters as well as the probability distribution function (PDF) of the intrinsic equatorial ellipticity of bulges. A new algorithm (GASP-2D) was used to perform the bidimensional bulge-disk decomposition of J-band galaxy images extracted from the archive of the 2MASS survey. The PDF of intrinsic ellipticities was derived from the distribution of the observed ellipticities of bulges and misalignments between bulges and disks. About 80% of bulges in S0-Sb galaxies are not oblate but triaxial ellipsoids. Their mean axial ratio in the equatorial plane is 〈B/A〉=0.85. There is not significant dependence of their PDF on morphology, light concentration, and luminosity. The scenarios in which bulges assembled from mergers and/or grew over long times through disk secular evolution have to be tested against the derived PDF of bulge intrinsic ellipticities.
Observations across nearby spiral bulges
Authors: Sansom A. E. , Loubser S. I. , Sánchez-Blázquez P. , Söchting I. K.
Published: July 2008

The bulges of spiral galaxies may be old, as in our Galaxy, or may possess younger stars, as evidenced in spectroscopic line strengths in some external bulges. Bulges look similar to elliptical galaxies, but their formation history is expected to differ due to the presence of the disc and different formation mechanisms. This project extends the numbers of high signal-to-noise, broad coverage spectra to a larger sample of bulges in order to test conflicting ideas about their age distributions. New Gemini long-slit observations will be used to derive stellar population ages and histories across 30 bulges. Here we present preliminary results from the sample.
Gaseous flows in galaxies
Authors: Combes Francoise
Published: July 2008

The gas component plays a major role in the dynamics of spiral galaxies, because of its dissipative character, and its ability to exchange angular momentum with stars in the disk. Due to its small velocity dispersion, it triggers gravitational instabilities, and the corresponding non-axisymmetric patterns produce gravity torques, which mediate these angular momentum exchanges. When a srong bar pattern develops with the same pattern speed all over the disk, only gas inside corotation can flow towards the center. But strong bars are not long lived in presence of gas, and multiple-speed spiral patterns can develop between bar phases, and help the galaxy to accrete external gas flowing from cosmic filaments. The gas is then intermittently driven to the galaxy center, to form nuclear starbursts and fuel an active nucleus. The various time-scales of these gaseous flows are described.
Central mass accumulation in nuclear spirals
Authors: Maciejewski Witold
Published: July 2008

In central regions of non-axisymmetric galaxies high-resolution hydrodynamical simulations indicate spiral shocks, which are capable of transporting gas inwards. The efficiency of transport is lower at smaller radii, therefore instead of all gas dropping onto the galactic centre, a roughly uniform distribution of high-density gas develops in the gaseous nuclear spiral downstream from the shock, and the shear in gas is very low there. These are excellent conditions for star formation. This mechanism is likely to contribute to the process of (pseudo-) bulge formation.
12CO(J=3→2) detections in bulges of low surface brightness galaxies with APEX
Authors: Galaz Gaspar , Cortes Paulo , Bronfman Leonardo , Rubio Monica
Published: July 2008

Using the APEX sub-millimeter telescope we have detected for the first time the CO rotational transition 12CO(J=3→2) in two of five low surface brightness galaxies. For galaxies with positive detection, the emission is detected in their bulges, with measured gas velocity dispersion of about 80 km/s and observed main-beam brightness temperature TM B ~ 10 mK. Using a standard CO to H2 conversion factor, we are able to estimate molecular gas masses for LSBs with positive detections, and upper limits for those LSBs with negative detections. Assuming a higher gas temperature for the generation of the 12CO(J=3→2) line compared to that for the 12CO(J=1→0) one, results suggest that a warm molecular gas component is present in bulges, indicating a radiation field preventing the formation of large cooler amounts of molecular gas, compared to high surface brightness galaxies with higher metallicity and likely more dust.
The structure of early-type galaxies from the ACS Virgo and Fornax cluster surveys: cores, nuclei and supermassive black holes
Authors: Ferrarese Laura , Côté Patrick
Published: July 2008

The core structure of early-type galaxies is revisited in light of recent results from the ACS Virgo and Fornax Cluster Surveys. These surveys are comprised of HST/ACS g, z band images for a representative sample of 143 early-type galaxies, spanning a factor 720 in B-band luminosity. The data indicates a clear transition in the core structure going from the brightest to the faintest galaxies. In contrast to previous claims, however, this transition is found to be a continuous function of galaxy magnitude. We characterize the core structure in terms of deviations of the observed surface brightness profile – measured within ~ 2% of the galaxy effective radius – relative to the inner extrapolation of the Sérsic law that best fits the profiles on larger scales. Virtually all galaxies fainter than MB ~ −20 mag contain distinct stellar nuclei, and are described by surface brightness profiles that lie above the Sérsic extrapolation, while the reverse is true for brighter galaxies. The latter are also known to host supermassive black holes. A relation between SBHs and stellar nuclei is suggested by the fact that both types of “central massive objects” contain the same fraction, 0.2% of the total mass of the host galaxy.
The (quite dark) stellar cluster around the supermassive black hole Sagittarius A* at the center of the Milky Way
Authors: Schödel Rainer , Eckart A.
Published: July 2008

High-resolution seeing limited and adaptive optics near-infrared imaging observations of the stellar cluster within about one parsec of the massive black hole Sagittarius A* allow us to obtain a detailed picture of the structure of the nuclear star cluster of the Milky Way. We find that the stellar number counts and the diffuse light of the unresolved stellar population can be described very well by a stellar density function in the form of a broken-power law. This agrees well with theoretical predictions on the structure of a dynamically relaxed star cluster around a massive black hole. However, the cusp slope is found to be too shallow, which may be related to mixing of different stellar populations and continuous star formation, phenomena that are not taken into account by current theory. Mass densities larger than 107 solar masses per pc3 are reached within 0.1 pc of the central black hole. Intriguingly, up to several tens of percent of the total cluster mass in the central parsec may be in the form of dark stellar remnants.
Dynamics of galactic nuclei: mass segregation and collisions
Authors: Freitag Marc , Dale James E. , Church Ross P. , Davies Melvyn B.
Published: July 2008

Massive black holes (MBHs) with a mass below ~ 107 M⊙ are likely to reside at the centre of dense stellar nuclei shaped by 2-body relaxation, close interactions with the MBH and direct collisions. In this contribution, we stress the role of mass segregation of stellar-mass black holes into the innermost tenths of a parsec and point to the importance of hydrodynamical collisions between stars. At the Galactic centre, collisions must affect giant stars and some of the S-stars.
Supermassive black holes from OASIS and SAURON integral-field kinematics
Authors: Cappellari Michele , Bacon R. , Davies Roger L. , de Zeeuw P. T. , Emsellem Eric , Falcón-Barroso Jesús , Krajnović Davor , Kuntschner Harald , McDermid Richard M. , Peletier Reynier F. , Sarzi Marc , van den Bosch Remco C. E. , van de Ven Glenn
Published: July 2008

Supermassive black holes are a key element in our understanding of how galaxies form. Most of the progress in this very active field of research is based on just ~30 determination of black hole masses, accumulated over the past decade. We illustrate how integral-field spectroscopy, and in particular our OASIS modeling effort can help improve the current situation.
Chemical evolution of Seyfert galaxies
Authors: Ballero Silvia K. , Matteucci Francesca , Ciotti Luca
Published: July 2008

We computed the chemical evolution of Seyfert galaxies, residing in spiral bulges, based on an updated model for the Milky Way bulge with updated calculations of the Galactic potential and of the feedback from the central supermassive black hole (BH) in a spherical approximation. We followed the evolution of bulges of masses 2 × 109 − 1011M⊙ by scaling the star-formation efficiency and the bulge scalelenght as in the inverse-wind scenario for ellipticals. We successfully reproduced the observed relation between the BH mass and that of the host bulge, and the observed peak nuclear bolometric luminosity. The observed metal overabundances are easily achieved, as well as the constancy of chemical abundances with the redshift.
Upper limits on the mass of supermassive black holes from STIS archival data
Authors: Beifiori A. , Corsini E. M. , Bontà E. Dalla , Pizzella A. , Coccato L. , Sarzi M. , Bertola F.
Published: July 2008

The growth of supermassive black holes (SMBHs) appears to be closely linked with the formation of spheroids. There is a pressing need to acquire better statistics on SMBH masses, since the existing samples are preferentially weighted toward early-type galaxies with very massive SMBHs. With this motivation we started a project aimed at measuring upper limits on the mass of the SMBHs that can be present in the center of all the nearby galaxies (D < 100 Mpc) for which STIS/G750M spectra are available in the HST archive. These upper limits will be derived by modeling the central emission-line widths ([N II] λλ6548, 6583, Hα and [S II] λλ6716, 6731) observed over an aperture of ~01 (R < 50 pc). Here we present our preliminary results for a subsample of 76 bulges.
A general relativistic model of galaxy bulges in GEDi paradigm
Authors: Coimbra-Araújo C. H. , Letelier P. S.
Published: July 2008

Recently a new approach was presented where astronomical objects as galaxies and clusters are idealized as self-gravitating systems living in a universe endowed with more than 3+1 dimensions. A such paradigm, named GEDi (Gravitation with Extra Dimensions), may solve exactly the missing mass problem for rotation curves of galaxies or gravitational lensing of clusters with no dark matter particles. Here we present an introductory discussion about the construction of a real galaxy using a Miyamoto-Nagai solution for isotropical coordinates to mimic spiral galaxies with bulges.
Central black hole mass determination for blazars
Authors: Fan J. H. , Yuan Y. H. , Huang Y. , Gao Y. , Hua T. X. , Liu Y.
Published: July 2008

In this paper, we used the method to determine the central black mass (M), and the boosting factor (δ), the propagation angle (Φ), and the distance along the axis to the site of the γ-ray production (d) as well for 32 γ-ray loud blazars with available variability timescales. If we take the intrinsic γ-ray luminosity to be λ times the Eddington luminosity, i.e. $L_{\gamma}^{in}=\lambda{L_{\hbox{\it \scriptsize Edd}}}$, then we have following results: the masses of the black hole are in the range of (0.9 ~ 101)×107M⊙(λ = 1.0) or (1.30 ~ 153)×107M⊙(λ=0.1).
Feeding black holes: tracing gas flows from the outskirts to the centers of galaxies
Authors: Haan S. , Schinnerer E. , Mundell C. G. , Combes F. , García-Burillo S. , Emsellem E.
Published: July 2008

We analyzed the distribution and kinematics of the atomic gas (HI) in 16 nearby spiral galaxies. Our results indicate that the morphology of the atomic gas and dynamically disturbed outer disks correlate with the AGN type present (Seyfert, LINER). From the combined HI and CO data (from the NUGA project), 2-dimensional maps of the gas flow are computed and gas inflow rates are derived as a function of radius within the disks.
Radio variability properties for sources at multi-frequencies
Authors: Liu Y. , Fan J. H. , Wang H. G.
Published: July 2008

Using three radio databases of the university of Michigan Radio Astronomy Observatory (UMRAO), the National Radio Astronomy Observatory (NRAO), and the Metsähovi Observatory, we analyzed the radio light curves by the power spectral analysis and CLEANest method in search for possible periodicity. Multiple periods are found in some sources at multi-frequencies. We adopted the wavelets for period analysis of unevenly sampled time series to search for the evolution of the parameters (period, amplitude) of possible periodicities. Some possible variation of these parameters are found.
The black hole-dark matter halo connection
Authors: Sabra Bassem M. , Akl Maya Abi , Chahine Gilbert
Published: July 2008

We explore the connection between the central supermassive blackholes (SMBH) in galaxies and the dark matter halo through the relation between the masses of the SMBHs and the maximum circular velocities of their host galaxies, as well as the relationship between stellar velocity dispersion of the spheroidal component and the circular velocity. We rely on a heterogeneous sample containing galaxies of all types. The only requirement is that the galaxy has direct measurements of its SMBH mass, MBH, circular velocity, vc, and velocity dispersion, σ. We present a direct observational MBH − vc relation.
Mass outflow constraints in active nuclei and quasars from X-ray spectroscopy
Authors: Yaqoob Tahir
Published: July 2008

Absorption in the X-ray spectra of active galactic nuclei from outflowing gas can be modeled to yield critical physical information on the outflows. The outflow rate of mass ejected back into the ISM of the host galaxy and the resulting feedback could potentially have an impact on evolution. We give a brief overview of the current observational constraints on the outflows that should be taken into account by models of evolution and feedback.
Rejuvenation of spiral bulges
Authors: Thomas Daniel , Davies Roger L.
Published: July 2008

We seek to understand whether the stellar populations of galactic bulges show evidence of secular evolution triggered by the presence of the disc. To this end we re-analyse the sample of Proctor & Sansom (2002), deriving stellar population ages and element abundances from absorption line indices as functions of central velocity dispersion and Hubble type. In agreement with other studies in the literature, we find that bulges have relatively low luminosity weighted ages, the lowest age derived being 1.3 Gyr. Hence bulges are not generally old, but actually rejuvenated systems. We discuss evidence that this might be true also for the bulge of the Milky Way. The smallest bulges are the youngest with the lowest α/Fe ratios indicating the presence of significant star formation events involving 10 − 30 per cent of their total mass in the past 1 − 2 Gyr. No significant correlations of the stellar population parameters with Hubble Type are found. We show that the above relationships with σ coincide perfectly with those of early-type galaxies. At a given velocity dispersion, bulges and elliptical galaxies are indistinguishable as far as their stellar populations are concerned. These results favour an inside-out formation scenario and indicate that the discs in spiral galaxies of Hubble types Sbc and earlier cannot have a significant influence on the evolution of the stellar populations in the bulge component. The phenomenon of pseudobulge formation must be restricted to spirals of types later than Sbc.
The secular evolution of M83 central bulge
Authors: Dottori H. , Diaz R. J. , Agüero M. P. , Mast D. , Rodrigues I.
Published: July 2008

The luminosity profile of M 83 bulge can be traced by a de Vaucouleurs' law between ≈ 200 pc and ≈ 800 pc. The inner part can be fitted by a n = −1/2 Sérsic profile. Also the IR (J − K) color shows difference between the periphery and the central part of the bulge, both properties indicating the presence of a pseudobulge. Previous Gemini-S 3-D, Paβ spectroscopy of the central ≈ 5″×13″ revealed spider like diagrams indicating disk like motion around three extended masses identified respectively with the optical nucleus (ON), with the center of the bulge isophotes, similar to the CO kinematical center (KC), and with a condensation hidden at optical wavelengths (HN), coincident with the largest lobe in 10 μm emission, most probably a cannibalized satellite. Numerical simulations show that they suffer strong evaporation and they would merge engulfing also the star forming arc in few hundred Myr, increasing the mass at the kinematical center by a factor o five or more. Upper mass limit of putative Black Holes associated to ON, KC and HN are a few ten thousand to a million solar masses. GMOS+Gemini imaging and spectroscopy of a chain of radio sources has yield no optical high redshift counterparts. This radio sources are aligned with ON, neither associated to SN nor to HII regions and might point to an older similar phenomenon, which left behind a kick-off spur.
Stellar populations in late-type spirals observed with SAURON
Authors: Ganda Katia , Peletier Reynier F. , Falcón-Barroso Jesús , McDermid Richard M.
Published: July 2008

We present results on the stellar populations of a sample of 18 late-type spirals, based on data acquired with the integral-field spectrograph SAURON at the WHT. We present the two-dimensional line-strength maps, the central line indices, and estimate the star formation time-scale. In an exponentially declining SFR scenario, we find a trend between the time-scale τ and the central velocity dispersion: more massive galaxies show shorter burst durations. A detailed study on these data is published by Ganda et al. (2007).
Correlations between the age structure in early-type galaxies and their properties
Authors: Hempel Maren
Published: July 2008

We present the results on our investigation of the age structure in early-type galaxies, based on optical/near-infrared photometry. First results have shown that the age structure in early-type galaxies is not as uniform as previously thought. The conclusion can only be that the formation of these galaxies is not exclussively based on a single scenario, e.g. monolithic collapse, or hierarchical merging. In our galaxy survey we compare the age structure of galaxies in different galaxy environment, of different mass and with different integral light properties, using the globular cluster systems as stellar probes. Depending on the size of the globular cluster sample we derive a cumulative age distribution and compare it to simulated systems with a known age structure. This allows us to detect globular cluster sub-populations with an age difference of several Gyr. So far we have found two galaxies, members of small groups of galaxies, which contain a significant population of intermediate age globular clusters in the inner region of the galaxy.
The centre of M83
Authors: Houghton Ryan C. W. , Thatte N.
Published: July 2008

Stellar kinematics show no evidence of hidden mass concentrations at the centre of M83. We show the clearest evidence yet of an age gradient along the starburst arc and interpret the arc to have formed from orbital motion away from a starforming region in the dust lane.
Nature of bulges in the Hubble sequence
Authors: Laurikainen Eija , Salo H. , Buta R. , Knapen J. H.
Published: July 2008

We evaluate the nature of bulges in the Hubble sequence, based on an analysis of 216 disk galaxies of all morphological types (S0-Sd). For this purpose we collect our various analysis made separately for early and late-type galaxies, published in a series of papers. Using the criteria by Kormendy & Kennicutt we find strong evidence of pseudobulges in all Hubble types, including S0s. However, due to the relatively massive bulges in S0-S0/a galaxies it is not probable that the (pseudo)bulges in these galaxies were formed in a similar manner as in spirals. More likely, pseudobulges particularly in strongly barred early-type disk galaxies are suggested to be a combination of star formation and the nearly exponential central components of bars.
Kinematics of the dwarf elliptical galaxy IC 225
Authors: Miller Bryan W. , Rudie Gwen
Published: July 2008

We present the 2D kinematics of the nuclear region of the double-nucleated low-luminosity elliptical galaxy IC 225. Observations with the GMOS-N IFU at Gemini Observatory show a large amount of metal-rich gas coincident with the off-center nucleus. However, preliminary kinematics analysis indicates that the velocity of the stars in the off-center nucleus is distinct from that of the gas at the same position. Therefore, this is an intriguing example of how the formation of a nucleus or bulge may be occurring in a low-luminosity elliptical galaxy.