Found 44 talks width keyword galactic formation
We compare the Hubble type and the spectroscopic class of the galaxies with spectra in SDSS/DR7. As it is long known, elliptical galaxies tend to be red whereas spiral galaxies tend to be blue, however, this relationship presents a large scatter, which we measure and quantify in detail. We compare the Automatic Spectroscopic K-means based classification (ASK) with most of the commonly used morphological classifications. All of them provide consistent results. Given a spectral class, the morphological type wavers with a standard deviation between 2 and 3 T types, and the same large dispersion characterizes the variability of spectral classes fixed the morphological type. The distributions of Hubble types given an ASK class are very skewed -- they present long tails that go to the late morphological types for the red galaxies, and to the early morphological types for the blue spectroscopic classes. The scatter is not produced by problems in the classification, and it remains when particular subsets are considered. A considerable fraction of the red galaxies are spirals (40--60 %), but they never present very late Hubble types (Sd or later). Even though red spectra are not associated with ellipticals, most ellipticals do have red spectra: 97 % of the ellipticals in the morphological catalog by Nair & Abraham, used here for reference, belong to ASK 0, 2 or 3. It contains only a 3 % of blue ellipticals. The galaxies in the green valley class (ASK~5) are mostly spirals, and the AGN class (ASK 6) presents a large scatter of Hubble types from E to Sd. We investigate variations with redshift using a volume limited subsample. From redshift 0.25 to now the galaxies redden from ASK 2 to ASK 0, as expected from the passive evolution of their stellar populations. Two of the ASK classes (1 and 4) gather edge-on spirals, and they may be useful in studies requiring knowing the intrinsic shape of a galaxy (e.g., weak lensing calibration).
AbstractGalaxies are arguably complex systems. However, they also display many scaling relations between their physical properties, hinting that it might be possible to summarize all this complexity within a few phenomenological parameters. In this talk, we will first address the question of how many parameters are indeed necessary in order to describe a galaxy, and then discuss some of them in detail, aiming towards a self-consistent, cartoon (yet remarkably accurate) picture of galaxy formation and evolution.
AbstractClusters of galaxies are expected to contain substantial population of cosmic-rays that can yield a significant high energy emission. Moreover, as they are heavily dark matter dominated, they must be considered prime targets for gamma-ray searches for WIMP decay or annihilation. I will present dark matter gamma-ray all-sky simulated Fermi maps of the Local Universe. The dark matter distribution is obtained from a constrained cosmological simulation provided by the CLUES project. I will discuss the possibility for the Fermi-LAT instrument to detect a dark matter gamma-ray signal in extragalactic structures, mainly nearby clusters, in a 5-year all-sky survey and discuss our on work in progress on cosmic-rays. We are also promoting a campaign of observation of the Perseus galaxy cluster with the MAGIC telescopes. Deep observations of nearby clusters with ground-based instruments are crucial to investigate the nature of dark matter as well as the possible gamma-ray emission coming from cosmic-ray acceleration in these environments.
CALIFA is the largest IFS survey ever performed up to date. Recently started, it will observe ~600 galaxies in the Local Universe with PPAK at the 3.5m of the Calar Alto Observatory, sampling most of the size of these galaxies and covering the optical wavelength range between 3700-7100 Å, using to spectroscopic setups. The main goal of this survey is to characterize the spatially resolved spectroscopic properties (both the stellar and ionized gas components) of all the population of galaxies at the current cosmological time, in order to understand in detail the how is the final product of the evolution of galaxies. To do so, the sample will cover all the possible galaxies within the color-magnitude diagram, down to MB ~ -18 mag, from big dry early-types to active fainter late-type galaxies. The main science drivers of the survey is to understand how galaxies evolve within the CM-diagram, understanding the details the process of star formation, metal enrichment, migrations and morphological evolution of galaxies.
AbstractSurvey operations with the VISTA telescope with it wide field near IR camera started in Feb 2010, following a science verification phase that started in Oct, 2009. I will describe this new 4.2m wide field telescope and the ESO VISTA Public survey program. I will give details of all ESO six public surveys which will be used for a range of galactic and extragalactic science. I am the PI of the largest, by area, VISTA survey, I will focus my talk on the VISTA Hemisphere Survey and I will show how this survey will be used to find quasars in the Epoch of Reionization at redshift greater than 7. The VISTA Hemisphere Survey (VHS) has been been awarded 300 clear nights on the 4.2m ESO VISTA telescopes. VHS observations started i February, 2010 and the survey will take 5 years to complete. The VHS will cover the whole southern celestial hemisphere (dec<0) to a depth 4 magnitudes fainter than 2MASS/DENIS in at least two wavebands J and K. In the South Galactic Cap, 5000 square degrees will be imaged deeper, including H band, and will have supplemental deep multi-band grizY imaging data provided by the Dark Energy Survey (DES). The remainder of the high galactic latitude sky will be imaged in YJHK and combined with ugriz wavebands from the VST ATLAS, SDSS BOSS and Skymapper optical surveys. The medium term scientific goals include: a huge expansion in our knowledge of the lowest-mass and nearest stars; deciphering the merger history and genesis of our own Galaxy; measurement of large-scale structure out to z=1 and measuring the properties of Dark Energy; discovery of the first quasars with z > 7. In my talk, I will describe the scientific motivation and methodology of the search for quasars with z > 7.
AbstractDespite speculation that both starburst and nuclear activity in galaxies may be intimately linked via the common triggering mechanism of mergers and interactions, very little is known about the true nature of the link. Thus, the role of AGN in the formation and evolution of galaxies is still not well established. I will present deep Gemini/GMOS imaging observations which are used to investigate the triggering mechanism(s) in a complete sample of radio-loud AGN for which, uniquely, we have quantified the level of both the AGN and star formation activity. I will show results on the proportion of powerful radio galaxies triggered in galaxy mergers and also on the link between the degree of star formation/AGN activity and the interaction status of the host galaxies.
AbstractWe present the results of our systematic search for optically elusive, but intrinsically luminous buried AGNs in >100 nearby (z < 0.3) luminous infrared galaxies with L(IR) > 1011 L⊙, classified optically as non-Seyferts. To disentangle AGNs and stars, we have performed (1) infrared 2.5-35 μ low-resolution (R ~ 100) spectroscopy using Subaru, AKARI, and Spitzer, to estimate the strengths of PAH (polycyclic aromatic hydrocarbon) emission and dust absorption features, (2) high-spatial-resolution infrared 20 micron imaging observations using Subaru and Gemini, to constrain the emission surface brightnesses of energy sources, and (3) millimeter interferometric measurements of molecular gas flux ratios, which reflect the physical and chemical effects from AGNs and stars. Overall, all methods provided consistent pictures. We found that the energetic importance of buried AGNs is relatively higher in galaxies with higher infrared luminosities (where more stars will be formed), suggesting that AGN-starburst connections are luminosity dependent. Our results might be related to the AGN feedback scenario as the possible origin of the galaxy down-sizing phenomenon.
Luminous high-redshift radio galaxies (HzRGs) are associated with the most massive known galaxies in the early Universe. These galaxies have the properties expected of the progenitors of dominant galaxies in rich clusters.
I shall describe the properties of HzRGs and demonstrate how they can be used to study the formation and evolution of galaxies and clusters. I shall also show how LOFAR, the new European radio telescope, can be used to extend these probes into the epoch of reionisation.
AbstractGalaxies are the basic building blocks of the Universe, and understanding their formation and evolution is crucial to many areas of current astrophysical research. Nearby galaxies, being the 'fossil record' of the evolution of galaxies, provide a wealth of detail to test extensively the current models of galaxy formation and evolution. A galaxy's structure is linked to both its mass and evolutionary history. Probing galactic structure requires understanding the distribution of stars among galaxies of all types and luminosities across the full range of environments. We are performing a complete volume-limited (d < 40 Mpc) survey of over 2200 nearby spiral, elliptical and dwarf galaxies at 3.6 and 4.5 μ in the Spitzer Warm Mission to address fundamental questions of galactic structure that are united by the common need for deep, uniform, unbiased maps of the stellar mass in galaxies. I will introduce the survey, give examples of images and of the science that can be done, and explain how other researchers at the IAC can become involved in analysing these exciting data.
AbstractΛCDM-based numerical simulations predict a scenario consistent with observational evidence in Milky Way-like halos. However, less clear is the role of low-mass galaxies in the big picture. The best way to answer this question is to study the nearest example of a dwarf spiral galaxy, M33. We will use star clusters to understand the structure, kinematics and stellar populations of this galaxy. We will present our current status and future plans of a comprehensive study of the star cluster system of M33. This study will provide key insights into the star formation history, composition and kinematics of low-mass galaxies as well as place M33 within the context of galaxy formation process.
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