Science.gov (United States)

single star evolution. To understand the evolution of massive stars and their role in shaping the galaxy, understanding of the distribution of ...

International Nuclear Information System (INIS)

Photometric and kinematic observations of the peculiar S0 galaxy IC 4767, the X-galaxy, are presented. At various intensities the bulge of this galaxy looks like a normal spheroidal system with elliptical isophotes, a well-defined rectangle, and a peanut-shaped or X-shaped structure with components aligned at oblique angles to the major axis. The observations reveal a rapidly rotating inner disk of gas and dust which is nearly aligned with the major axis. The presence of gaseous emission alone suggests an accretion event. The stars in the outer regions of the X-component are rotating nearly as rapidly as the gas in the main disk, indicating that they are in relatively circular orbits. The five most prominent peanut-shaped bulges all have several nearby companions, evidence that the peanut deformity is due to interaction between galaxies. An analogy with the formation mechanism proposed for polar-ring ...

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We study double Higgs boson production at future linear colliders while paying special attention to the option of high-energy and high-luminosity photon beams. The main purpose is to examine the feasibility of {ital e}{sup +}{ital e}{sup {minus}}, {gamma}{ital e}, and {gamma}{gamma} colliders in order to establish bounds on the value of triple Higgs coupling, which could be crucial for understanding a spontaneous breaking mechanism. We consider mainly those cases of light and intermediate Higgs bosons, including an analysis of the electroweak backgrounds. The mass range {ital M}{sub {ital H}}{approximately}{ital M}{sub {ital Z}} is discussed separately. It is shown that for a light Higgs boson the {ital H}{sup 3} coupling can be visible, even at a future linear {ital e}{sup +}{ital e}{sup {minus}} collider at 500 GeV. For an intermediate Higgs boson, a collider with TeV energies is ...

CERN Document Server

Large hadron collider set to restart

CERN Document Server

The galaxies of the Local Group that are currently forming stars can serve as our laboratories for understanding star formation and the evolution of massive stars. In this talk I will summarize what I think we've learned about these topics over the past few decades of research, and briefly mention what I think needs to happen next.

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Recent studies in elementary particle physics have made the need for an e{sup +}e{sup -} linear collider able to reach energies of 500 GeV and above with high luminosity more compelling than ever [1]. Observations and measurements completed in the last five years at the SLC (SLAC), LEP (CERN), and the Tevatron (FNAL) can be explained only by the existence of at least one particle or interaction that has not yet been directly observed in experiment. The Higgs boson of the Standard Model could be that particle. The data point strongly to a mass for the Higgs boson that is just beyond the reach of existing colliders. This brings great urgency and excitement to the potential for discovery at the upgraded Tevatron early in this decade, and almost assures that later experiments at the LHC will find new physics. But the next generation of experiments to be mounted by the world-wide particle physics community must not only find this new physics, they ...

International Nuclear Information System (INIS)

New surface photometry of all known elliptical galaxies in the Virgo cluster is combined with published data to derive composite profiles of brightness, ellipticity, position angle, isophote shape, and color over large radius ranges. These provide enough leverage to show that Sersic log I #propor to# r "1"/"n functions fit the brightness profiles I(r) of nearly all ellipticals remarkably well over large dynamic ranges. Therefore, we can confidently identify departures from these profiles that are diagnostic of galaxy formation. Two kinds of departures are seen at small radii. All 10 of our ellipticals with total absolute magnitudes M_V_T #<=# -21.66 have cuspy cores-"missing light"-at small radii. Cores are well known and naturally scoured by binary black holes (BHs) formed in dissipationless ("dry") mergers. All 17 ellipticals with -21.54 #<=# M_V_T #<=# -15.53 do not have cores. We find a new distinct component in these ...

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No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

Wonderful opportunities await particle physics over the next decade, with the coming of the Large Hadron Collider at CERN to explore the 1-TeV scale (extending efforts at LEP and the Tevatron to unravel the nature of electroweak symmetry breaking) and many initiatives to develop our understanding of the problem of identity: what makes a neutrino a neutrino and a top quark a top quark. Here I have in mind the work of the B factories and the Tevatron collider on CP violation and the weak interactions of the b quark; the wonderfully sensitive experiments at Brookhaven, CERN, Fermilab, and Frascati on CP violation and rare decays of kaons; the prospect of definitive accelerator experiments on neutrino oscillations and the nature of the neutrinos; and a host of new experiments on the sensitivity frontier. We might even learn to read experiment for clues about the dimensionality of spacetime. If we are inventive enough, we may be ...

CERN Document Server

Flawless start for world's mightiest particle collider

KoreaScience (Korea)

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CERN Document Server

We use direct N-body simulations to investigate the evolution of star clusters with large size-scales with the particular goal of understanding the so-called extended clusters observed in various Local Group galaxies, including M31 and NGC6822. The N-body models incorporate a stellar mass function, stellar evolution and the tidal field of a host galaxy. We find that extended clusters can arise naturally within a weak tidal field provided that the tidal radius is filled at the start of the evolution. Differences in the initial tidal filling-factor can produce marked differences in the subsequent evolution of clusters and the size-scales that would be observed. These differences are more marked than any produced by internal evolution processes linked to the properties of cluster binary stars or the action of an intermediate-mass black hole, based on models performed in this work and previous work to date. Models evolved in a ...

CERN Document Server

We report the results of the evaluation of the ``concentration-density'' relation of galaxies in the local universe, taking advantage of the very large and homogeneous data set available from the Las Campanas Redshift Survey (Shectman et al. 1996). This data set consists of galaxies inhabiting the entire range of galactic environments, from the sparsest field to the densest clusters, thus allowing us to study environmental variations without combining multiple data sets with inhomogeneous characteristics. Concentration is quantified by the automatically-measured concentration index $C$, which is a good measure of a galaxy's bulge-to-disk ratio. The environment of the sample galaxies is characterized both by the three-space local galaxy density and by membership in groups and clusters. We find that the distribution of C in galaxy populations varies both with ...

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Short communication.

International Nuclear Information System (INIS)

Short communication.

Energy Technology Data Exchange (ETDEWEB)

Short communication.

CERN Document Server

The Large Hadron Collider and the Long-Term Scientific programme of CERN: Executive Summary

International Nuclear Information System (INIS)

An account is given of the existence of kinematic subsystems in elliptical galaxies, in conjunction with discussions of the application of statistical tests to determine whether ellipticals are triaxial, and of the modified Faber-Jackson relation for elliptical galaxies. Recent data obtained by Kormendy (1988) and Dressler and Richstone (1988) on the kinematics of the M31, M32, and NGC 4594 central regions indicate both very steep rotation curves and peaked velocity dispersion profiles. If elliptical galaxies are triaxial, and if it is common for them to have accreted other galaxies during their evolution, then both a source of fuel for an active nucleus and a mechanism for getting that fuel from outside the galaxy into its center is available. 61 refs.

Science.gov (United States)

believe the system is similar to the face-on spiral and companion known as M51, the Whirlpool Galaxy. Tomorrow's picture: Sleeping Beauty < Archive | Index | Search | Calendar |...

Science.gov (United States)

to be similar to the system of face-on spiral and small companion known as M51, the Whirlpool Galaxy. Tomorrow's picture: Beta Pic < | Archive | Index | Search | Calendar | RSS |...

UK PubMed Central (United Kingdom)

In this model, without dark matter, the flat rotation curves of galaxies and the mass-to-light ratios of clusters of galaxies are described quantitatively. The hypothesis is that the agent of gravitational...Full Text Available

International Nuclear Information System (INIS)

The mechanism proposed by Kormendy (1984) for the formation of counterrotating cores in elliptical galaxies is investigated using self-consistent numerical simulations of mergers between a high- and a low-luminosity elliptical galaxies. The conditions for a counterrotation to appear are determined, observational properties of the remnants are described, and the evolution of the structural and kinematic parameters of the larger galaxy is analyzed. It is shown that a counterrotation results only when the merging orbits are retrograde, due to a large change in the secondary spin during the merger. 36 refs.

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(Jun 1974). United States Kormendy, J. Hale Observatories, Pasadena,

International Nuclear Information System (INIS)

We study the signals for composite vector leptoquarks in e"+e- colliders (CERN e"+e- collider LEP II, Next Linear Collider, and CERN Linear Collider) through their effects on the production of jet pairs, as well as their single and pair productions. We also analyze their production in #gamma#e and #gamma##gamma# collisions.

CERN Document Server

Recent wide-field imaging observations of the X-ray luminous cluster RDCSJ1252.9-2927 at z=1.24 uncovered several galaxy groups that appear to be embedded in filamentary structure extending from the cluster core. We make a spectroscopic study of the galaxies in these groups using GMOS on Gemini-South and FORS2 on VLT with the aim of determining if these galaxies are physically associated to the cluster. We find that three groups contain galaxies at the cluster redshift and that they are probably bound to the cluster. This is the first confirmation of filamentary structure as traced by galaxy groups at z>1. We then use several spectral features in the FORS2 spectra to determine the star formation histories of group galaxies. We find a population of relatively red star-forming galaxies in the groups that are absent from the cluster core. ...

CERN Document Server

AIM:Learn more about the origin of shells and dust in early type galaxies. METHOD: V-I colours of shells and underlying galaxies are derived, using HST Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in wedges and subtracted to determine shell profiles and colours. We applied Voronoi binning to our data to get smoothed colour maps of the galaxies. Comparison with N-body simulations from the literature gives more insight to the origin of the shell features. Shell positions and dust characteristics are inferred from model galaxy subtracted images. RESULT: The ACS images reveal shells well within the effective radius in some galaxies (at 1.7 kpc in the case of NGC 5982). In some cases, strong nuclear dust patches prevent detection of inner shells. Most shells have colours which are similar to the underlying galaxy. Some ...

International Nuclear Information System (INIS)

The diameters d/sub r/ of inner ring structures in disk galaxies are used as geometric distance indicators to derive the distances of 453 spiral and lenticular galaxies, mainly in the distance interval 4<#delta#<63 Mpc. The diameters are weighted means from the catalogs to Kormendy, Pedreros and Madore, and the authors. The distances are calculated by means of the two- and three-parameter formulae of Paper II; the adopted mean distance moduli #mu#"0(r) have mean errors from all sources of 0.6--0.7 mag for the well-observed galaxies.

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The characteristics and evolution of dwarf spheroidal galaxies (DSGs) are modeled on the basis of high-resolution CCD photometry obtained with the Canada-France-Hawaii telescope and reported by Kormendy (1986). The data and the results of core-parameter correlation studies are presented in extensive graphs and discussed. It is inferred that at least some DSGs are formed by the stripping of gas from dwarf spiral and irregular galaxies, although internal gas processes may also be important. The hypothesis that DSGs represent the faint end of the elliptical-galaxy sequence appears to be ruled out. 50 references.

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The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly{alpha} forest, and a radial velocity search for planets around {approx}8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes 5-band imaging of roughly 5200 deg{sup 2} in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg{sup 2}, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), ...

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I review the physic prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking.

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I review the physic prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking.

International Nuclear Information System (INIS)

The possibility to transform the future linear e"+e"-colliders into the #gamma#e and #gamma##gamma# colliders with approximately the same energies and luminosities was shown earlier. Their properties are compared from the point of view of possible physical investigations on them. 10 refs.; 1 tab.

International Nuclear Information System (INIS)

A #gamma##gamma# collider would extend and complement the physics capability of a linear collider; e.g. it would be suitable for direct measurement of the partial decay width of a Higgs boson into two gamma quanta. This paper discusses choice of laser parameters, luminosity optimization, electron and laser parameters for a gamma- gamma collider as a second interaction region for the Next Linear Collider, laser path, and the lasers. It is concluded that a gamma- gamma collider is technically feasible; however it will require a significant investment in preparatory R ampersand D.

International Nuclear Information System (INIS)

A bulge-disk decomposition is made for 737 spiral and lenticular galaxies drawn from a Sloan Digital Sky Survey galaxy sample for which morphological types are estimated. We carry out the bulge-disk decomposition using the growth curve fitting method. It is found that bulge properties, effective radius, effective surface brightness, and also absolute magnitude, change systematically with the morphological sequence; from early to late types, the size becomes somewhat larger, and surface brightness and luminosity fainter. In contrast, disks are nearly universal, their properties remaining similar among disk galaxies irrespective of detailed morphologies from S0 to Sc. While these tendencies were often discussed in previous studies, the present study confirms them based on a large homogeneous magnitude-limited field galaxy sample with morphological types estimated. The systematic change of bulge-to-total ...

Science.gov (United States)

Breakdowns occurring in rf accelerating structures will limit the ultimate performance of future linear colliders such as the Compact Linear Collider (CLIC). Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN to better understand the vacuum breakdown mechanism in a simple setup. Measurements of the field enhancement factor ? show that the local breakdown field is constant and depends only on the electrode material. With copper electrodes, the local breakdown field is around 10.8GV/m, independent of the gap distance. The ? value characterizes the electrode surface state, and the next macroscopic breakdown field can be well predicted. In breakdown rate experiments, where a constant field is applied to the electrodes, clusters of consecutive breakdowns alternate with quiet periods. The occurrence and lengths of these clusters and quiet periods depend on the evolution of ...

International Nuclear Information System (INIS)

The world fusion program has advanced to the stage where it is appropriate to construct a number of devices for the purpose of burning DT fuel. In these next-generation experiments, the expected flux and fluence of 14 MeV neutrons and associated gamma rays will pose a significant challenge to the operation and diagnostics of the fusion device. Radiation effects include structural damage to materials such as vacuum windows and seals, modifications to electrical properties such as electrical conductivity and dielectric strength and impaired optical properties such as reduced transparency and luminescence of windows and fiber optics during irradiation. In preparation for construction and operation of these new facilities, the fusion diagnostics community needs to work with materials scientists to develop a better understanding of radiation effects, and to undertake a testing program aimed at developing workable solutions for this multi-faceted problem. A unique ...

CERN Document Server

Context: The colliding-wind binary Eta Car exhibits soft X-ray thermal emission that varies strongly around periastron, and non-thermal emission seen in hard X-rays and gamma-rays. Aims: To definitively identify Eta Car as the source of the hard X-ray emission, to examine how changes in the 2-10 keV band influence changes in the hard X-ray band, and to understand more clearly the mechanisms producing the non-thermal emission using new INTEGRAL observations obtained close to periastron. Methods: A Chandra observation encompassing the ISGRI error circle was analysed, and all other soft X-ray sources (including the outer shell of Eta Car itself) were discarded as likely counter-parts. New hard X-ray images of Eta Car were studied close to periastron, and compared to previous observations far from periastron. Results: The INTEGRAL component, when represented by a power law (with a photon index of 1.8), would produce more emission in the Chandra ...

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A brief overview, from an experimentalist`s point of view, of the possibilities and difficulties involved in building a photon-photon collider using beams produced in Compton backscattering from a linear e{sup +}e{sup -} or e{sup -}e{sup -}collider. Some hindsight is included from the successful March 1994 Berkeley workshop on gamma-gamma colliders. (author). 13 refs., 2 figs.

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Short communication.

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It seems to be very natural that whole program for constructing and exploring of linear colliders (including photon colliders as the substantial part) should be divided by stages according to the increasing beam energy. We discuss the main stages of this program and the set of physical problems for each stage photon colliders. ((orig.))

CERN Document Server

An energy frontier or QCD Explorer ep and collider can be realized by colliding high-energy photons generated by Compton backscattered off a CLIC electron beam, at either 75 GeV or 1.5 TeV, with protons or ions stored in the LHC. In this study we discuss a performance optimization of this type of collider by tailoring the parameters of both CLIC and LHC. An estimate of the ultimately achievable luminosity is given.

CERN Document Server

This note studies the single production of scalar or vector diquarks at the LHeC collider.

CERN Document Server

We present the results of an isophotal shape analysis of three samples of galaxies in the Coma cluster. Quantitative morphology, together with structural and photometric parameters, is given for each galaxy. Special emphasis has been placed on the detailed classification of early-type galaxies. The three samples are: i) a sample of 97 early-type galaxies brighter than m_B = 17.00 falling within one degree from the center of the Coma cluster; these galaxies were observed with CCD cameras, mostly in good to excellent resolution conditions; ii) a magnitude complete sample of 107 galaxies of all morphological types down to m_B = 17.00 falling in a circular region of 50 arcmin diameter, slightly offcentered to the North-West of the cluster center; the images for this and the next sample come from digitized photographic plates; iii) a complete comparison sample of 26 ...

CERN Document Server

We present results of a study of large-scale neutral hydrogen (HI) gas in nearby radio galaxies. We find that the early-type host galaxies of different types of radio sources (compact, FR-I and FR-II) appear to contain fundamentally different large-scale HI properties: enormous regular rotating disks and rings are present around the host galaxies of a significant fraction of low power compact radio sources, while no large-scale HI is detected in low power, edge-darkened FR-I radio galaxies. Preliminary results of a study of nearby powerful, edge-brightened FR-II radio galaxies show that these systems generally contain significant amounts of large-scale HI, often distributed in tail- or bridge-like structures, indicative of a recent galaxy merger or collision. Our results suggest that different types of radio galaxies may have a different ...

Science.gov (United States)

on the picture will download the highest resolution version available. M51: The Whirlpool Galaxy Credit: W. Keel (U. Alabama), 1.1-meter Hall Telescope, Lowell Observatory...

Science.gov (United States)

Clicking on the image will bring up the highest resolution version available. The Whirlpool Galaxy in Infrared Dust Credit: Infrared: NASA, ESA, M. Regan & B. Whitmore (STScI),...

Science.gov (United States)

on the picture will download the highest resolution version available. M51: The Whirlpool Galaxy in Dust and Stars Credit: Credit: N. Scoville (Caltech), T. Rector (U....

International Nuclear Information System (INIS)

United States Kormendy, J. Sargent, WLW Hale Observatories, California

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A remarkably simple argument successfully accounts for the rate of star formation in different galaxies. The snag is that the timescale is uncomfortably short.

International Nuclear Information System (INIS)

A sample of 41 radio-galaxies with 13.0<=msub(corr)<=15.5 has been analyzed to test the angular redshift anisotropy discovered on Sc I galaxies by Rubin, Rubin and Ford (1973). The sample does not present their anisotropy but contains an even more curious distribution of radial velocities which suggests that the Rubin-Ford effect results from an anomalous redshift of light when it travels through clusters of galaxies. (Auth.).

International Nuclear Information System (INIS)

Surface photometry of bulges and elliptical galaxies is reviewed. The properties of cores and nuclei as revealed by improvements in seeing and the use of CCDs are examined, and newly discovered structural details such as dust, shells, and dynamical subsystems which show the importance of accretion events in galactic evolution are addressed. Improved constraints on galaxy formation resulting from better measurements of parameter scaling laws are discussed, and accurate measurements of departures from elliptical isophotes and of color gradients obtained with CCDs are considered.

CERN Document Server

Dwarf galaxies are generally faint. To derive their age and metallicity distributions, it is critical to optimize the use of any collected photon. Koleva et al., using full spectrum fitting, have found strong population gradients in some dwarf elliptical galaxies. Here, we show that the population profiles derived with this method are consistent and more precise than those obtained with spectrophotometric indices. This allows studying fainter objects in less telescope time.

International Nuclear Information System (INIS)

Recent observations of the evolutionary properties of paired and interacting galaxies are reviewed, with special emphasis on their global emission properties and star formation rates. Data at several wavelengths provide strong confirmation of the hypothesis, proposed originally by Larson and Tinsley, that interactions trigger global bursts of star formation in galaxies. The nature and properties of the starbursts, and their overall role in galactic evolution are also discussed.

International Nuclear Information System (INIS)

This paper discusses the results of the absorption-line spectroscopy carried out with the Canada-France-Hawaii Telescope on the prototypical Sa galaxy NGC 4594 (the Sombrero galaxy). Two conclusions were derived concerning this galaxy. First, at the values of r less than 10 arcsec, there is a well-defined nuclear disk of stars which is not obviously connected to the main disk at larger radii. Second, the mass-to-light ratio, M/L(V), of the galaxy rises abruptly at r values less than 1 arcsec to values of M/L(V) greater than 50, which is at least 10 times as large as the mass-to-light ratios at r values above 2 arcsec. This implies the presence of a central dark mass of a magnitude between 10 to the 8.5th and 10 to the 9.5th solar masses. 54 references.

International Nuclear Information System (INIS)

We study the relation between size and star formation activity in a complete sample of 225 massive (M_* > 5 x 10"1"0 M _s_u_n) galaxies at 1.5 < z < 2.5, selected from the FIREWORKS UV-IR catalog of the CDFS. Based on stellar population synthesis model fits to the observed rest-frame UV-NIR spectral energy distributions, and independent MIPS 24 #mu#m observations, 65% of the galaxies are actively forming stars, while 35% are quiescent. Using sizes derived from two-dimensional surface brightness profile fits to high-resolution (FWHM_P_S_F #approx# 0.''45) ground-based ISAAC data, we confirm and improve the significance of the relation between star formation activity and compactness found in previous studies, using a large, complete mass-limited sample. At z #approx# 2, massive quiescent galaxies are significantly smaller than massive star-forming galaxies, and a median factor of 0.34 #+-# 0.02 ...

CERN Document Server

We study the evolution of the cold gas content of galaxies by splitting the interstellar medium into its atomic and molecular hydrogen components, using the galaxy formation model GALFORM in the LCDM framework. We calculate the molecular-to-atomic hydrogen mass ratio, H2/HI, in each galaxy using two different approaches; the pressure-based empirical relation of Blitz & Rosolowsky and the theoretical model of Krumholz, McKeee & Tumlinson, and apply them to consistently calculate the star formation rates of galaxies. We find that the model based on the Blitz & Rosolowsky law predicts an HI mass function, CO(1-0) luminosity function, correlations between the H2/HI ratio and stellar and cold gas mass, and infrared-CO luminosity relation in good agreement with local and high redshift observations. The HI mass function evolves weakly with redshift, with the number density of high mass ...

International Nuclear Information System (INIS)

We present ultraviolet through far-infrared (FIR) surface brightness profiles for the 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). The imagery used to measure the profiles includes Galaxy Evolution Explorer UV data, optical images from Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and Sloan Digital Sky Survey, near-IR data from Two Micron All Sky Survey, and mid- and FIR images from Spitzer. Along with the radial profiles, we also provide multi-wavelength asymptotic magnitudes and several nonparametric indicators of galaxy morphology: the concentration index (C 42), the asymmetry (A), the Gini coefficient (G), and the normalized second-order moment of the brightest 20% of the galaxy's flux (M-bar20). In this paper, the first of a series, we describe the technical aspects regarding the surface photometry, and present a basic analysis ...

International Nuclear Information System (INIS)

This talk summarizes recent progress in top quark physics studies for high energy linear electron-positron colliders as presented at the LCWS2000 Workshop at Fermilab. New results were presented for top pair production at threshold and in the continuum, as well as for top production at #gamma##gamma# colliders.

CERN Document Server

When it was first developed, the standard model predicted a collection of particles, and thanks to more and more powerful colliders, physicsists have been able to find them all except one: the Higgs-Boson.

CERN Document Server

The CKM angle $\\gamma/\\phi_{3}$ had been measured by two B-factories, the PEPII collider for the BaBar experiment and the KEKB collider for the Belle experiments. The present paper reports recent progress in $\\gamma/\\phi_{3}$.

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Detectors for a photon-photon collider are envisaged using as guide-lines the physics goals and the interaction point environment. Production of SUSY Higgs scalar and pseudo-scalar is emphasized. Some aspects of the interaction point environment are discussed. ((orig.)).

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At future {gamma} {gamma} colliders a massive production of tt-bar pairs is possible. This would allow a detailed investigation of the interactions involving the top quark. The authors propose some correlations which are sensitive to tt-bar final state interactions and compute the QCD and standard model Higgs boson contributions to these correlation. QCD-induced transverse polarization of top quarks is found to be sizeable and measurable at a high-energy e{sup +} e{sup -} collider with an integrated luminosity of 10(fb){sup -1} which is converted into a photon collider by backscattering of laser photons. 16 refs.

International Nuclear Information System (INIS)

German 2003 p. 24 Germany Klemz, G. Moenig, K. Sekaric, J. Stahl,

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We discuss the search of excited leptons and quarks with spin 1/2 at {gamma}{gamma} and at {gamma}e colliders. We show that {gamma}{gamma} colliders have important advantages for the observation of excited leptons and quarks in comparison with ee, ep, and pp colliders discussed in previous papers. These collisions give a simple test for the chirality of the l{sup *}l{gamma} transition. The anomalous magnetic moment of excited leptons can be observed when its value is not too small. (orig.).

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We have made preliminary estimates of charged particles background at the 100x100 GeV Photon Linear Collider with ultimate luminosity. The charged particles background due to electromagnetic processes is located mainly in the small-angle range of the detector. At large angles, the number of background particles is much smaller. Analysis of the background (at least, in the range under consideration) shows that background conditions for the VLEPP-based Photon Linear Collider are better than at the VLEPP electron-positron collider. ((orig.)).

International Nuclear Information System (INIS)

We present a summary of the discussions in the Exotic Collider Concepts Group. Most of the discussions were centered around the status and open problems for muon-muon and gamma-gamma colliders. In addition the group discussed some general problems and new results of accelerator physics. copyright 1995 American Institute of Physics.

International Nuclear Information System (INIS)

The heavy Higgs bosons H,A of the minimal supersymmetric extension of the Standard Model can be produced as resonances in high-energy #gamma##gamma# colliders. Prospects of the search for these particles in bb-bar and neutralino-pair final states are studied in this report. Heavy Higgs bosons can be found with masses up to about 70-80% of the initial e"+e"- collider energy for moderate values of tan #beta#, i.e. in areas of the parameter space not accessible at other colliders.

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We discuss the main stages of a physical program for photon linear colliders. We consider the problems in electroweak theory, hadron physics, QCD, and nonlinear QED, as well as new particles and interactions, etc. The discussed stages constitute the parts of an entire ambitious program for linear colliders. ((orig.)).

CERN Document Server

We present a study of 66 barred, early-type (S0-Sb) disk galaxies, focused on the disk surface brightness profile outside the bar region and the nature of Freeman Type I and II profiles, their origins, and their possible relation to disk truncations. This paper discusses the data and their reduction, outlines our classification system, and presents $R$-band profiles and classifications for all galaxies in the sample. The profiles are derived from a variety of different sources, including the Sloan Digital Sky Survey (Data Release 5). For about half of the galaxies, we have profiles derived from more than one telescope; this allows us to check the stability and repeatability of our profile extraction and classification. The vast majority of the profiles are reliable down to levels of mu_R ~ 27 mag arcsec^-2; in exceptional cases, we can trace profiles down to mu_R > 28. We can typically follow disk profiles out to at ...

International Nuclear Information System (INIS)

Central velocity dispersions and rotation curves to radii of approx.5 kpc have been measured for 32 galaxies, mostly field S0's. Our rotation curves confirm the result of Kormendy and Illingworth that the bulges of S0 galaxies are in rapid rotation, with enough rotational kinetic energy to account for their flattenings. The V/sigma-ellipticity relation we find for S0 bulges is compared with similar data for elliptical galaxies from Davies et al. We conclude that (1) faint SO bluges and elliptical galaxies (M/sub B/ fainter than -20.5) are both consistent with oblate rotators with isotropic velocity dispersions (although in our sample, S0 bluges are flatter, on the average, than ellipticals) and (2) bright S0 bulges, -22.0

CERN Document Server

Of the many ways of detecting high redshift galaxies, the selection of objects due to their redshifted Ly-alpha emission has become one of the most successful. But what types of galaxies are selected in this way? Until recently, Ly-alpha emitters were understood to be small star-forming galaxies, possible building-blocks of larger galaxies. But with increased number of observations of Ly-alpha emitters at lower redshifts, a new picture emerges. Ly-alpha emitters display strong evolution in their properties from higher to lower redshift. It has previously been shown that the fraction of ultra-luminous infrared galaxies (ULIRGs) among the Ly-alpha emitters increases dramatically between redshift three and two. Here, the fraction of AGN among the LAEs is shown to follow a similar evolutionary path. We argue that Ly-alpha emitters are not a homogeneous class of objects, and that the ...

CERN Document Server

Using the Sloan Digital Sky Survey (SDSS) and the FIRST (Faint Images of the Radio Sky at Twenty Centimeters) catalogs, we examined the optical environments around double-lobed radio sources. Previous studies have shown that multi-component radio sources exhibiting some degree of bending between components are likely to be found in galaxy clusters. Often this radio emission is associated with a cD-type galaxy at the center of a cluster. We cross-correlated the SDSS with the FIRST catalog and measured the richness of the cluster environments surrounding both bent and straight multi-component sources. This led to the discovery and classification of a large number of galaxy clusters out to a redshift of z ~ 0.5. We divided our sample into smaller subgroups based on their optical and radio properties. We find that FR I radio sources are more likely to be found in galaxy clusters than FR II sources. Further, ...

CERN Document Server

We have discovered seven type Ia cluster supernovae (SNe) in the course of the Wise Observatory Optical Transients Search in the fields of galaxy clusters with redshifts between z=0.06 and z=0.2. Two of these events, SN 1998fc in Abell 403 (z=0.10) and SN 2001al in Abell 2122/4 (z = 0.066), have no obvious hosts. Both events appear projected on the halos of the central cD galaxies, but have velocity offsets of 750-2000 km/s relative to those galaxies, suggesting they are not bound to them. We use deep Keck imaging of the locations of the two SNe to put upper limits on the luminosities of possible dwarf hosts, M_R > -14 mag for SN 1998fc and M_R > -11.8 mag for SN 2001al. The fractions of the cluster luminosities in dwarf galaxies fainter than our limits are less than 3 x 10^-3 and 3 x 10^-4, respectively. Thus, 2/7 of the SNe would be associated with less than 3 x 10^-3 of the luminosity ...

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A guide to practical astronomy. It introduces the reader to some basic (and some not-so-basic) astronomical concepts, and discusses the stars and their evolution, the planets, nebulae, and distant galaxies

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The analysis of images (of obtained in various ranges of the lengths of waves) of luminous objects in the Universe by means of a method of multilevel dynamic contrasting led author to the conclusions: a) the structures of all observable galaxies represents a complicated constructions which have the tendency to self-similarity and made of separate (basic) blocks, which are a coaxially tubular structures and a cartwheel-like structures; b) the majority of observable objects in the Universe are luminous butt-ends of almost invisible (of almost completely transparent) of filamentary formations which structures are seen only near to their luminous butt-ends; c) the result of analysis of images of cosmic objects show the structure of many pairs of cooperating galaxies point to opportunity of their formation at butt-ends generated in a place of break of the similar filament; d) the interacting galaxies (M 81 and M 82) show they ...

Science.gov (United States)

... Fig.9 Hurricane Fran, Sept.4, 1996, (NOAA / NASA) Fig.10 Whirlpool Galaxy (M 51/NGC 5194), C. Messier (1773) / P. Mechain (1781) ...

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Observation of lithium lines in two halo stars could bring some information about /sup 7/Li abundance at the time of the formation of the galaxy.

CERN Document Server

We performed a spectroscopic galaxy survey, complete to $m_{F814W}\\leq20.3$ ($L_B>0.15L_B^{\\star}$ at z=0.3), within 100x100'' of the quasar Q1127-145 ($z_{em}=1.18$). The VLT/UVES quasar spectrum contains three $z_{abs}<0.33$ MgII absorption systems. We obtained eight new galaxy redshifts, adding to the four previously known, and galaxy star formation rates (SFRs) and metallicities were computed where possible. A strong MgII system [$W_r(2796)=1.8$A], which is a known damped Ly$\\alpha$ absorber (DLA), had three previously identified galaxies; we found two additional galaxies associated with this system. These five galaxies form a group with diverse properties, such as a luminosity range of $0.04\\leq L_B\\leq0.63 L_B^{\\star}$, an impact parameter range of $17\\leq D \\leq 241$ kpc and velocity dispersion of $\\sigma$=115 km/s. The DLA group ...

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These include, but are not limited to: stellar winds and outflows, post-main- sequence stellar evolution, binary/multiple star evolution, globular cluster structure ...

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Numerical simulations show that box-shaped bulges of edge-on galaxies are not bulges: they are bars seen side-on. Therefore, the two components that are seen in edge-on Sb galaxies such as NGC 4565 are a disk and a bar. But face-on SBb galaxies always show a disk, a bar, and a (pseudo)bulge. Where is the (pseudo)bulge in NGC 4565? We use archival Hubble Space Telescope H-band images and Spitzer Space Telescope 3.6 #mu#m wavelength images, both calibrated to Two Micron All Sky Survey K_s band, to penetrate the prominent dust lane in NGC 4565. We find a high surface brightness, central stellar component that is clearly distinct from the boxy bar and from the disk. Its brightness profile is a Sersic function with index n = 1.55 #+-# 0.07 along the major axis and 1.33 #+-# 0.12 along the minor axis. Therefore, it is a pseudobulge. It is much less luminous than the boxy bar, so the true pseudobulge-to-total luminosity ratio of ...

Science.gov (United States)

... The second scenario is limited by the age of our Galaxy such that the lowest-mass WD that could be formed via single star evolution is ~0.47 M ...

Science.gov (United States)

creating such active galactic nuclei as quasars. Strangely, the center of this fiery whirlpool is offset from the exact center of the galaxy - for a reason that for now remains an...

Science.gov (United States)

the picture will download the highest resolution version available. Supernovae in the Whirlpool Image Credit & Copyright: R Jay Gabany Explanation: Where do spiral galaxies keep...

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Compton backscattering of laser photons near the interaction point of an e{sup +}e{sup -} or e{sup -}e{sup -} collider can be used to produce a {gamma}-{gamma} or {gamma}-e{sup -} collider. This paper describes the laser requirements, including pulse duration, intensity, energy, and wavelength, for such a collider. For most of the proposed, next generation, e{sup +}e{sup -} colliders, the laser wavelength should be in the near-infrared, with a pulse duration of 1 ps or less and an energy of similar 1 J per pulse. Current chirped pulse amplification laser systems in solid state lasing materials are well suited to meet these requirements. These systems are described. ((orig.)).

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Although the standard model of particle physics agrees perfectly with experimental data, it is unlikely the final theory describing particles and their interactions. New phenomena has been searched in the jets and missing transverse energy topology. Such phenomena may be due to the pair production of leptoquarks decaying into a quark and a neutrino or the pair production of stops decaying into a charm and a neutralino which is assumed to be the lightest supersymmetric particle. These searches have been performed with the Ddiamter detector at hadronic collider TeVatron with a center of mass energy of 1.96 TeV. This kind of searches needs a good understanding of the jet energy calibration. The determination of the relative jet energy scale has allowed us to reduce the systematic uncertainties on the jet energy measurement when comparing the data and the simulation. Moreover a new method has been developed in order to correct simulated jets for ...

International Nuclear Information System (INIS)

High resolution imagery of the clumpy irregular galaxy Mkn 325 shows that some clumps have sizes approximately 300 pc while some may still be unresolved and approximately < 100 pc. In spite of dimensions comparable to - or even smaller than - those of the giant H II complex 30 Doradus, one clump has a star formation rate 100 times higher. (author).

International Nuclear Information System (INIS)

The results that can be expected by e#gamma# and #gamma##gamma# colliders in future are summarized. e#gamma# and #gamma##gamma# colliders have many fine possibilities, and are the economical selection for utilizing future e"+e"- colliders more effectively. e#gamma# and #gamma##gamma# colliders were proposed by former USSR researchers at the beginning of 1980s, but recently, the prospect of realizing future e"+e"- collision type linear accelerator projects has become high, they have become to be considered seriously as the option of remodeling them. The high energy photon beam of e#gamma# and #gamma##gamma# colliders is obtained by causing Compton reverse scattering, irradiating laser beam to the electron beam of e"+e"- accelerators. The production of #gamma#-beam is explained. As for the physics noteworthy in e#gamma# colliders, abnormal gauge coupling, the ...

International Nuclear Information System (INIS)

In this report, I surveyed physics potential of the #gamma##gamma# option of a linear e"+e"- collider with the following questions in mind: What new discovery can be expected at a #gamma##gamma# collider in addition to what will be learned at its 'parent' e"+e"- linear collider? By taking account of the hard energy spectrum and polarization of colliding photons, produced by Compton back-scattering of laser light off incoming e"- beams, we find that a #gamma##gamma# collider is most powerful when new physics appears in the neutral spin-zero channel at an invariant mass below about 80% of the c.m. energy of the colliding e"-e"- system. If a light Higgs boson exists, its properties can be studied in detail, and if its heavier partners or a heavy Higgs boson exists in the above mass range, they may be discovered at a #gamma##gamma# collider. CP ...

International Nuclear Information System (INIS)

We report the discovery of an active galactic nucleus (AGN) pair in the interacting galaxy system IRAS 20210+1121 at z = 0.056. An XMM-Newton observation reveals the presence of an obscured (N _H #approx# 5 x 10"2"3 cm"-"2), Seyfert-like (L _2_-_1_0_k_e_V = 4.7 x 10"4"2 erg s"-"1) nucleus in the northern galaxy, which lacks unambiguous optical AGN signatures. Our spectral analysis also provides strong evidence that the IR-luminous southern galaxy hosts a Type 2 quasar embedded in a bright starburst emission. In particular, the X-ray primary continuum from the nucleus appears totally depressed in the XMM-Newton band as expected in the case of a Compton-thick absorber, and only the emission produced by Compton scattering ('reflection') of the continuum from circumnuclear matter is seen. As such, IRAS 20210+1121 seems to provide an excellent opportunity to witness a key, early phase in the quasar evolution predicted by the ...

CERN Document Server

Cosmological hydrodynamical simulations as well as observations indicate that spiral galaxies are comprised of five different components: dark matter halo, stellar disc, stellar bulge, gaseous disc and gaseous halo. While the first four components have been extensively considered in numerical simulations of binary galaxy mergers, the effect of a hot gaseous halo has usually been neglected even though it can contain up to 80% of the total gas within the galaxy virial radius. We present a series of hydrodynamic simulations of major mergers of disc galaxies, that for the first time include a diffuse, rotating, hot gaseous halo. Through cooling and accretion, the hot halo can dissipate and refuel the cold gas disc before and after a merger. This cold gas can subsequently form stars, thus impacting the morphology and kinematics of the remnant. Simulations of isolated systems with total mass M~10^12Msun show ...

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The second list of objects in the Second Biurakan Spectral Sky Survey of the region centered on alpha 09h50m, delta +55 deg 00 arcmin is given. The list contains data on 110 objects and galaxies of a peculiar physical nature and 24 blue stars. The observations were made with the 40-52 arcsec Schmidt telescope of the Biurakan Astrophysical Observatory with a set of three objective prisms using Kodak IIIaJ and IIIaF emulsions sensitized in nitrogen. The area is found to contain 20 quasar candidates and four Seyfert galaxies, 27 blue stellar objects, 24 galaxies with an appreciable ultraviolet continuum, and 39 emission galaxies without appreciable ultraviolet radiation. The surface brightness of the quasars and Seyferts on the considered area down to the limiting magnitude 19.5 M is more than 1.5 per square degree with allowance for the already known quasars. The surface density of emission ...

CERN Document Server

The traditional view that Ly-alpha emission and dust should be mutually exclusive has been questioned more and more often, notably the observations of Ly-alpha emission from ULIRGs seems to counter this view. In this paper we seek to address the reverse question: How large a fraction of Ly-alpha selected galaxies are ULIRGs? Using two samples of 24/25 Ly-alpha emitting galaxies at z = 0.3/2.3 we perform this test, also including results at z = 3.1, and find that whereas the ULIRG fraction at z = 3.1 is very small, it systematically increases towards lower redshifts. There is a hint that this evolution may be quite sudden and that it happens around a redshift of z ~ 2.5. Measuring the infrared luminosities of the Ly-alpha emitters, we find that they are in the normal to ULIRG range in the lower redshift sample, whereas the higher redshift galaxies all have luminosities in the ULIRG category. The Ly-alpha escape fractions for ...

CERN Document Server

Dynamical friction, or the rate for a satellite to decay its orbit in a host galaxy halo, is often severely overestimated when applying the ChandraSekhar's formula without correcting for the tidal loss of the satellite and the adiabactic growth of the host galaxy potential over the Hubble time. As a satellite decays to the inner and denser region of the host galaxy, the high ambient density boosts the exchange of energy and angular momentum between the satellite and the host, but on the other hand shrinks the Roche lobe of the satellite by tides. Eventually the processes of orbital decay and tidal stripping hang up altogether once the satellite is light enough. These competing processes can be modeled analytically for a satellite if we parametrize the massloss history by an empirical formula. We also take into account the adiabatic contraction of orbits due to growth of the potential well of the host ...

International Nuclear Information System (INIS)

Beams may be viewed as directed and focussed flow of energy and information, carried by particles and electromagnetic radiation fields (ie, photons). Often, they interact with each other (eg, in high energy colliders) or with other forms of matter (eg, in fixed targets, sychrotron radiation, neutron scattering, laser chemistry/physics, medical therapy, etc.). The whole art and science of beams revolve around the fundamental quest for, and ultimate implementation of, mechanisms of production, storage, control and observation of beams -- always directed towards studies of the basic structures and processes of the natural world and various practical applications. Tremendous progress has been made in all aspects of beam physics and technology in the last decades -- nonlinear dynamics, superconducting magnets and rf cavities, beam instrumentation and control, novel concepts and collider praradigms, to name a few. We illustrate this progress with a ...

International Nuclear Information System (INIS)

We review some interesting virtual effects from the minimal supersymmetric model (MSSM) at #gamma##gamma# colliders. We conclude that in the research respects, such as supersymmetric particle pair production, CP-violation and electroweak-like one-loop corrections in top quark pair production, the FCNC in the R_p-violating MSSM, linear collider (LC) operating in photon-photon collision mode provides powerful facilities in the measurements of new physics objects. For a precise and thorough study of the new physics, the investigation of the supersymmetric quantum effects is necessary. (author)

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The heavy neutral Higgs bosons H, A in the minimal supersymmetric extension of the standard model can be produced as single resonances at high-energy {gamma}{gamma} colliders. We have studied the prospects of the search for these particles in bb and neutralino-pair final states. The Higgs bosons can be found with masses up to 70-80% of the initial e{sup {+-}}e{sup -} collider energy for medium values of tg{beta}, i.e. in areas of the supersymmetric parameter space not accessible at other colliders. (orig.)

International Nuclear Information System (INIS)

Three possibilities to observe the Higgs-top interaction at future #gamma##gamma#-colliders are discussed: a) associated Higss production via the #gamma##gamma##->#tanti tH reaction, b) Higgs obliged radiative correction to the #gamma##gamma##->#tanti t channel, c) Higgs resonance production via #gamma##gamma##->#H#->#ZZ. The results obtained show windows of the Higss mass where the Yukawa interaction of the Higss with the top quark can be studied at #gamma##gamma#-colliders. (orig.).

International Nuclear Information System (INIS)

We present the efficient technique to extract the signal of the intermediate mass Higgs boson from the backgrounds at future #gamma##gamma# colliders. For a clear Higgs detection, it is important to fit the original electron accelerator energy depending on the Higgs mass, to set the polarization of the photon beams and to apply the efficient b quark tagging method. we demonstrate the extraction of information of Higgs parameters and the new physics from the observable physical quantities. It is clearly shown that a future #gamma##gamma# collider will have a rich potential for study on the new physics, as well as the Higgs physics. (author).

Energy Technology Data Exchange (ETDEWEB)

We investigate the chargino production process {gamma}{gamma} {yields} (W-tilde){sup +}(W-tilde){sup -} at high energy {gamma}{gamma} colliders in the framework of the minimal supersymmetric standard model (MSSM). Here the high energy {gamma} beams are obtained by the backward Compton scattering of the laser flush by the electron in the basic linear TeV ee colliders. We consider the polarization of the laser photons as well as the electron beams. Appropriate beam polarization could be effective to enhance the cross section to for us extract the signal from the dominant background {gamma}{gamma} {yields} W{sup +}W{sup -}. (author).

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"The US must develop a compelling bid to host the International Linear Collider in order to safeguard American science." (1,5 page)

International Nuclear Information System (INIS)

The future e"+e"- linear colliders can also operate in the e#gamma# or #gamma##gamma# modes. In the context of the top-color assisted technicolor (TC2) model, we study the single charged top-pion production process #gamma##gamma# #-># tb-bar#PI#_t"-. The results show that the production rates can reach the level of tens fb with reasonable parameter values. So one can expect that enough signals could be produced in future high-energy linear collider experiments. Furthermore, the flavor-changing (FC) decay mode #PI#_t"- #-># bc-bar is the best channel to detect the charged top pion due to the clean standard model background. With a large number of events and the clean background, the charged top pion should be observable at future linear colliders operating in #gamma##gamma# mode at the TeV energy scale

Science.gov (United States)

Aug 21, 2003 ... Her research interests have included hot stars, colliding stellar winds, binary star evolution and evolved stellar companions. ...

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The authors present some recent measurements on electroweak physics using data collected by the CDF experiment at the Tevatron proton anti-proton collider ({radical}s = 1.96 TeV) at Fermilab.

British Library Electronic Table of Contents (United Kingdom)

Abstract We address the fundamental question of matching the rest-frame K-band luminosity function (LF) of galaxies over the Hubble time using semi-analytic models after modification of the stellar population modelling. We include the Maraston evolutionary synthesis models, which feature a higher contribution by the thermally pulsating asymptotic giant branch (TP-AGB) stellar phase, into three different semi-analytic models, namely the De Lucia and Blaizot version of the Munich model, morgana and the Menci model. We leave all other input physics and parameters unchanged. We find that the modification of the stellar population emission can solve the mismatch between models and the observed rest-frame K-band luminosity from the brightest galaxies derived from UKIRT Infrared Deep Sky Survey d...

CERN Document Server

Dark matter particles form halos that contribute the major part of the mass of galaxy clusters. The formation of these cosmological structures have been investigated both observationally and in numerical simulations, which have confirmed the existence of a universal mass profile. However, the dynamic behaviour of dark matter in halos is not as well understood. We have used observations of 16 equilibrated galaxy clusters to show that the random velocities of dark matter particles are larger on average along the radial direction than along the tangential, and that the magnitude of this velocity anisotropy is radially varying. Our measurement implies that the collective behaviour of dark matter particles is fundamentally different from that of normal particles and the radial variation of the anisotropy velocity agrees with the predictions of numerical simulation.

CERN Document Server

The study of extragalactic planetary nebulae (EPN) is a rapidly expanding field. The advent of powerful new instrumentation such as the PN spectrograph has led to an avalanche of new EPN discoveries both within and between galaxies. We now have thousands of EPN detections in a heterogeneous selection of nearby galaxies and their local environments, dwarfing the combined galactic detection efforts of the last century. Key scientific motivations driving this rapid growth in EPN research and discovery have been the use of the PNLF as a standard candle, as dynamical tracers of their host galaxies and dark matter and as probes of Galactic evolution. This is coupled with the basic utility of PN as laboratories of nebula physics and the consequent comparison with theory where population differences, abundance variations and star formation history within and between stellar systems informs both stellar and galactic evolution. Here ...

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We analyze spin correlations between top quark and anti-top quark produced at polarized e{sup +} e{sup -} and {gamma}{gamma} colliders. We consider a generic spin basis to find a strong spin correlation. Optimal spin decompositions for top quark pair are presented for e{sup +}e{sup -} and {gamma}{gamma} colliders. We show the cross- section in these bases and discuss the characteristics of results.

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We investigate the possibility of observing strong interactions of longitudinally polarized weak vector bosons in the process {gamma}{gamma} {yields} ZZ at a photon linear collider. We make use of polarization of the photon beams and cuts on the decay products of the Z bosons to enhance the signal relative to the background of transversely polarized ZZ pairs. We find that the background overwhelms the signal unless there are strong resonant effects, as for instance from a technicolor analogue of the hadronic f{sub 2}(1270) meson.

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The production of three vector bosons in {gamma} {gamma} collisions studying the reactions {gamma} + {gamma} {yields} W{sup +} + W{sup -} + Z{sup 0} and {gamma} + {gamma} {yields} W{sup +} + W{sup -} + {gamma}. 12 refs., 4 figs., 2 tabs.

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The beams in electron linear colliders can be converted to nearly monochromatic photon beams by means of Compton backscattering of laser photons. The electron beams must then be diverted from the interaction point by some means, the best of which seems to be a plasma lens. This paper describes the constraints on the plasma lens in this application and shows how the ablation of solid hydrogen pellets might be able to produce plasmas to satisfy these constraints. ((orig.)).

International Nuclear Information System (INIS)

The complementarity of e"+e"- and #gamma##gamma# colliders to discover and explore new physics beyond the Standard Model (SM) is discussed. After briefly surveying a number of various new physics scenarios, we concentrate in detail on signatures for Large Extra Dimensions via the process #gamma##gamma##->#WW.

International Nuclear Information System (INIS)

It is proposed to measure the spot sizes and polarization of #gamma# beams of future #gamma#e and #gamma##gamma# colliders detecting e"+e"- pairs produced as a result of interaction of high energy #gamma# quanta with density modulated and not modulated laser photons. The quantum electrodynamics cross sections, necessary numerical results as well as a short comparison of the proposed method with some other methods are given. (orig.).

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We investigate the scope of all relevant production modes of charged Higgs bosons in the MSSM, with mass larger than the one of the top quark, at future Linear Colliders operating in {gamma}{gamma} mode at the TeV energy scale. Final states with one or two H{sup {+-}} bosons are considered, as produced by both tree- and loop-level interactions. (orig.)

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The electroweak-symmetry-breaking sector of the standard model can be weakly-coupled or can be strongly-coupled, which is characterized by some kinds of strong interaction among the Goldstone bosons of the electroweak-symmetry-breaking sector. In this paper, we summarize an investigation of probing the strong electroweak-symmetry-breaking effects at photon colliders. ((orig.)).

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The working group reviewed the main difficulties foreseen in doing physics at a gamma-gamma collider. They discussed the requirements for the detector, calculated some of the signal and background rates, compared methods of measuring luminosity, looked at how to get the laser beams in, investigated ways of sweeping aside the electrons and considered ways of disposing of the used beams. No overwhelming obstacles were found but important questions still need to be answered. ((orig.)).

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The Tevatron collider at Fermilab provides a very rich environment for the study B{sub s} mesons. In this paper they show a few selected topics from the CDF and D0 collaborations, giving special attention to the B{sub s} Mixing analyses. This note corresponds to the proceedings of the Hadron Collider Physics 2005 conference.

CERN Document Server

Boxy and peanut-shaped bulges are seen in about half of edge-on disc galaxies. Comparisons of the photometry and major-axis gas and stellar kinematics of these bulges to simulations of bar formation and evolution indicate that they are bars viewed in projection. If the properties of boxy bulges can be entirely explained by assuming they are bars, then this may imply that their hosts are pure disc galaxies with no classical bulge. A handful of these bulges, including that of the Milky Way, have been observed to rotate cylindrically, i.e. with a mean stellar velocity independent of height above the disc. In order to assess whether such behaviour is ubiquitous in boxy bulges, and whether a pure disc interpretation is consistent with their stellar populations, we have analysed the stellar kinematics and populations of the boxy or peanut-shaped bulges in a sample of five edge-on galaxies. We placed slits along the major axis of ...

CERN Document Server

We examine the star clusters in the irregular galaxy NGC 4449. We use a near-infrared spectrum and broad-band images taken with the HST to place a limit of 8--15 Myrs on the age of the bright central ojbect in NGC 4449. Its luminosity and size suggest that it is comparable to young super star clusters. However, there is a peculiar nucleated-bar structure at the center of this star cluster, and we suggest that this structure is debris from the interaction that has produced the counter-rotating gas systems and extended gas streamers in the galaxy. From the images we identify 60 other candidate compact star clusters in NGC 4449. Fourteen of these could be background elliptical galaxies or old globular star clusters. Of the star clusters, three, in addition to the central object, are potentially super star clusters, and many others are comparable to the populous clusters found in the LMC. The star clusters span a large range in ...

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Comparative studies of flocculent and grand-design spirals suggest that density waves are not the predominant trigger of star formation in most galaxies. Implications for chemical evolution are profound. It may be possible to ignore the details of the spiral-wave phenomenon in research aimed at unifying the chemical properties of spiral disks. 16 references.

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The paper reviews the main observational data on pulsars, both the individual characteristics of pulsars and the properties they possess as members of the Galaxy. Consideration is then given to pulsar ages and to pulsar initial periods. An attempt is made to clarify the 'true' ages of pulsars.

UK PubMed Central (United Kingdom)

We describe the characteristics of the rapidly rotating molecular disk in the nucleus of the mildly active galaxy NGC4258. The morphology and kinematics of the disk are delineated by the point-like...Full Text Available

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This review covers research done at Lawrence Livermore National Laboratory under DOE contract. Areas of research are as follows: star evolution supernovae, and nucleosynthesis; stellar atmospheres and winds; galaxies and interstellar space; and high-energy astrophysics.

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It is shown that a natural consequence of the binary pulsar's evolution is a neutron star collision. Such a collision is expected to eject neutron-rich matter of an r-process character. Taking reasonable estimates for the number of such events over the history of the galaxy, it may be that they account for all of the r-process nuclei.

UK PubMed Central (United Kingdom)

Recent technological advances have lead to the ability to generate large amounts of data for model and non-model organisms. Whereas, in the past, there have been a relatively small number of central...Full Text Available

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Space Telescope is six years old today! Tomorrow's picture: In the Center of the Whirlpool | Archive | Index | Search | Glossary | Education | About APOD | See Explanation....

International Nuclear Information System (INIS)

We consider single production of leptoquarks (LQ's) at e"+e- and #gamma##gamma# colliders, for two values of the center-of-mass energy: #sq root#s =500 GeV and 1 TeV. We find that LQ's which couple within the first generation are observable for LQ masses almost up to the kinematic limit, both at e"+e- and #gamma##gamma# colliders, for an LQ coupling strength equal to #alpha#_e_m. The cross sections for single production of second- and third-generation LQ's at e"+e- colliders are too small to be observable. In #gamma##gamma# collisions, on the other hand, second-generation LQ's with masses much larger than #sq root#s /2 can be detected. However, third-generation LQ's can be seen at #gamma##gamma# colliders only for masses at most #approx# #sq root#s /2, making their observation more probable via the pair production mechanism.

International Nuclear Information System (INIS)

We investigate the sparticle production processes e#gamma# #-># e tilde(Z tilde)_1 and #gamma##gamma# #-># (f tilde)(f tilde and bar) at high energy e#gamma# and #gamma##gamma# colliders in the framework of the minimal supersymmetric standard model (MSSM). It will be shown that the e#gamma# colliders would be more suitable in searching for the heavy selectrons than ee colliders because of the low mass threshold of the process e#gamma# #-># (e tilde)(Z tilde)_1. We show that the standard background processes e#gamma# #-># #nu#W and eZ can be suppressed in terms of initial beam polarization as well as the kinematical cuts on the energy and angle of the final electron. Moreover, it will be argued that the experimental measurements of the cross sections for the processes e#gamma# #-># (e tilde)(Z tilde)_1 and #gamma##gamma# #-># (f tilde and bar)(f tilde) could enable us to constrain the basic parameters in ...

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The expected interstellar antiproton spectrum arising from cosmic-ray interactions in the Galaxy is recalculated, and the modulation of both antiprotons and protons is calculated using a two-dimensional modulation model incorporating gradient and curvature drifts and a wavy current sheet as well as the usual diffusion, convection, and energy-loss effects. Significant differences in the antiproton/proton ratio for different solar magnetic field polarities are predicted as well as a 'low-energy' component for antiprotons below about 1 GeV. 28 refs.

International Nuclear Information System (INIS)

We derive stellar masses, ages, and star formation histories (SFHs) of massive early-type galaxies in the z = 1.237 RDCS1252.9-2927 cluster and compare them with those measured in a similarly mass-selected sample of field contemporaries drawn from the Great Observatories Origin Deep Survey South Field. Robust estimates of these parameters are obtained by comparing a large grid of composite stellar population models with 8-9 band photometry in the rest-frame near-ultraviolet, optical, and IR, thus sampling the entire relevant domain of emission of the different stellar populations. Additionally, we present new, deep U-band photometry of both fields, giving access to the critical far-ultraviolet rest frame, in order to empirically constrain the dependence of the most recent star formation processes on the environment. We also analyze the morphological properties of both samples to examine the dependence of their scaling relations on their mass and environment. We ...

International Nuclear Information System (INIS)

We present the 24 #mu#m rest-frame luminosity function (LF) of star-forming galaxies in the redshift range 0.0 #<=# z #<=# 0.6 constructed from 4047 spectroscopic redshifts from the AGN and Galaxy Evolution Survey of 24 #mu#m selected sources in the Booetes field of the NOAO Deep Wide-Field Survey. This sample provides the best available combination of large area (9 deg"2), depth, and statistically complete spectroscopic observations, allowing us to probe the evolution of the 24 #mu#m LF of galaxies at low and intermediate redshifts while minimizing the effects of cosmic variance. In order to use the observed 24 #mu#m luminosity as a tracer for star formation, active galactic nuclei (AGNs) that could contribute significantly at 24 #mu#m are identified and excluded from our star-forming galaxy sample based on their mid-IR spectral energy distributions or the detection of X-ray emission. Optical ...

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The possible parameters of a photon linear collider at its ultimate luminosity, based on the VLEPP physics and technology V.E. Balakin et al., Proc. 6th Nat. Conf. on Accelerators, Dubna, 1978; V.E. Balakin, Proc. 4th Int. Workshop on Next Generation Linear Colliders, Garmisch, 1992, are presented. At a photon energy of 100x100 GeV the maximum achievable luminosity is about 1x10{sup 36} cm{sup -2} s{sup -1}. Beam parameters, luminosity characteristics, and ways to reduce the background are considered as well. ((orig.)).

International Nuclear Information System (INIS)

The production of pairs of doubly charged vector bileptons is studied at future #gamma##gamma# colliders. The unpolarized cross section for the #gamma##gamma##->#Y"-"-Y"+"+ subprocess is analytically calculated and convoluted to predict the number of events in the complete e"+e"-#->##gamma##gamma##->#Y"-"-Y"+"+ process. The gauge or nongauge character of the vector bilepton Y"#+-#"#+-# is discussed. It is found that, as a consequence of its spectacular signature, as it decays dominantly into two identical charged leptons, and also due to its charge contents, which significantly enhance the cross section, the detection of this class of particles with mass in the sub-TeV region can be at the reach of these colliders. The model-independent nature of our results is stressed.

British Library Electronic Table of Contents (United Kingdom)

A study of elliptical flow is carried out for different mass asymmetries of colliding nuclei using the reactions of Formula Not Shown ( Formula Not Shown ), Formula Not Shown ( Formula Not Shown ) and Formula Not Shown ( Formula Not Shown ). The present reactions are simulated at incident energies between 50 and 250 MeV/nucleon within the framework of isospin-dependent quantum molecular dynamics model. For the present analysis, total mass of colliding pairs is kept fixed and mass asymmetry is varied between 0.3 and 0.7. The elliptical flow shows a transition from in-plane to out-of-plane in the mid rapidity region with incident energy. The transition energy is found to increase with the mass asymmetry for light charged particles. A good agreement is obtained with experimental measurements.

International Nuclear Information System (INIS)

It has been recently suggested by Arkani-Hamed, Dimopoulos and Dvali that gravity may become strong at energies not far above the electroweak scale and thus remove the hierarchy problem. Such a scenario can be tested at both present and future accelerators since towers of Kaluza-Klein gravitons and associated scalar fields now play an important phenomenological role. In this paper we examine several processes for their sensitivity to a low scale for quantum gravity including deep inelastic ep scattering at DESY HERA, high precision low energy #nu#N scattering, Bhabha and Mo/ller scattering at linear colliders and both fermion and gluon pair production at #gamma##gamma# colliders. copyright 1999 The American Physical Society

Energy Technology Data Exchange (ETDEWEB)

It has been recently suggested by Arkani-Hamed, Dimopoulos and Dvali that gravity may become strong at energies not far above the electroweak scale and thus remove the hierarchy problem. Such a scenario can be tested at both present and future accelerators since towers of Kaluza-Klein gravitons and associated scalar fields now play an important phenomenological role. In this paper we examine several processes for their sensitivity to a low scale for quantum gravity including deep inelastic ep scattering at HERA, high precision low energy {nu}N scattering, Bhabha and Moller scattering at linear colliders and fermion pair production at {gamma}{gamma} colliders.

International Nuclear Information System (INIS)

We study the constraints on the anomalous coupling g_5"Z that can be obtained from the analysis of the reaction #gamma##gamma##->#W"+W"-Z at future linear e"+e"- colliders. We find out that a 0.5 (1) TeV e"+e"- collider operating in the #gamma##gamma# mode can probe values of g_5"Z of the order of 0.15 (4.5x10"-"2) for an integrated luminosity of 10 fb"-"1. This shows that the ability to search for this anomalous interaction of the #gamma##gamma# mode is better than the one of the usual e"+e"- mode, and it is similar to the ability of the e#gamma# mode.

International Nuclear Information System (INIS)

One of the main challenges for a high energy #gamma##gamma# collider is the high repetition rate required for the laser-electron-beam collisions to convert into high energy gamma beams. State-of-the-art, high power lasers have a much lower repetition rate than that of the electron pulses. It is therefore highly desirable that the same laser pulse can be reused. As an example, for NLC where beams collide at 120 Hz, within each collision cycle there are 90 electron bunches separated by 1.4 ns between successive bunches. We show, by invoking a recently invented laser optical box, that the laser pulses can be reused for the entire train of bunches within each collision cycle. ((orig.)).

International Nuclear Information System (INIS)

Stellar rotation and velocity-dispersion measurements are presented for the bulge components of the SBO galaxies NGC 1023, 2859, 2950, 4340, 4371, and 7743. The kinematics of nine SB bulges with data available are compared with bulges of unbarred galaxies studied by Kormendy and Illingworth. All of the SB bulges are found to rotate at least as rapidly as oblate-spheroid dynamical models which are flattened by rotation. This result confirms the conclusion of Kormendy and Illingworth that bulges rotate very rapidly. Six SB bulges found by Kormendy and Koo to be triaxial rotate even more rapidly than the oblate models. In this respect, they resemble published n-body models of bars. That is, triaxial bulges are dynamically like bars and unlike elliptical galaxies, which are also believed to be triaxial, but which rotate slowly. Measured velocity anisotropies are found to be consistent with these conclusions. Two ordinary bulges ...

International Nuclear Information System (INIS)

We report five new measurements of central black hole masses based on Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2 observations with the Hubble Space Telescope (HST) and on axisymmetric, three-integral, Schwarzschild orbit-library kinematic models. We selected a sample of galaxies within a narrow range in velocity dispersion that cover a range of galaxy parameters (including Hubble type and core/power-law surface density profile) where we expected to be able to resolve the galaxy's sphere of influence based on the predicted value of the black hole mass from the M-#sigma# relation. We find masses for the following galaxies: NGC 3585, M _B_H = 3.4"+"1"."5 _-_0_._6 x 10"8 M _s_u_n; NGC 3607, M _B_H = 1.2"+"0"."4 _-_0_._4 x 10"8 M _s_u_n; NGC 4026, M _B_H = 2.1"+"0"."7 _-_0_._4 x 10"8 M _s_u_n; and NGC 5576, M _B_H = 1.8"+"0"."3 _-_0_._4 x 10"8 M _s_u_n, all significantly excluding ...

CERN Multimedia

"American dominance in the study and development of high-energy particle physics may be seriously compromised, according to a report issued by the National Academy of Sciences, unless efforts are made to ensure that the next high-energy particle accelerator - the International Linear Collider (ILC) - will be constructed in the U.S.

Energy Technology Data Exchange (ETDEWEB)

The future e{sup +}e{sup -} linear colliders can also operate in the e{gamma} or {gamma}{gamma} modes. In the context of the top-color assisted technicolor (TC2) model, we study the single charged top-pion production process {gamma}{gamma} {yields} tb-bar{pi}{sub t}{sup -}. The results show that the production rates can reach the level of tens fb with reasonable parameter values. So one can expect that enough signals could be produced in future high-energy linear collider experiments. Furthermore, the flavor-changing (FC) decay mode {pi}{sub t}{sup -} {yields} bc-bar is the best channel to detect the charged top pion due to the clean standard model background. With a large number of events and the clean background, the charged top pion should be observable at future linear colliders operating in {gamma}{gamma} mode at the TeV energy scale.

International Nuclear Information System (INIS)

We consider the possibility of detecting a heavy Higgs boson (m_H>2m_Z) in proposed #gamma##gamma# colliders through the semileptonic mode #gamma##gamma##->#H#->#ZZ#->#q bar ql"+l-. We show that due to the nonmonochromatic nature of the photon beams produced by the laser-backscattering method, the resultant cross section for Higgs production is much smaller than the on-resonance cross section, and generally decreases with increasing collider energy. Although continuum ZZ production is expected to be negligible, we demonstrate the presence of, and calculate sizable backgrounds from, #gamma##gamma##->#l"+l-Z,q bar qZ, with Z#->#q bar q,l"+l-, respectively, and #gamma##gamma##->#t bar t#->#b bar bl"+l-#nu# bar #nu#. This channel may be used to detect a Higgs boson of mass m_H up to around 350 GeV at a 0.5 TeV e"+e- collider, assuming a nominal yearly luminosity of 10--20 fb"-"1.

International Nuclear Information System (INIS)

The neutral Higgs boson is expected to have a mass in the region 90 endash 150thinspGeV /c"2 in various schemes within the minimal supersymmetric extension of the standard model. A first generation muon collider is uniquely suited to investigate the mass, width, and decay modes of the Higgs boson, since the coupling of the Higgs boson to muons is expected to be strong enough for it to be produced in the s channel mode in the muon collider. Because of the narrow width of the Higgs boson, it is necessary to measure and control the energy of the individual muon bunches to a precision of a few parts in a million. We investigate the feasibility of determining the energy scale of a muon collider ring with circulating muon beams of 50thinspGeV energy by measuring the turn by turn variation of the energy deposited by electrons produced by the decay of the muons. This variation is caused by the existence of an average initial ...

International Nuclear Information System (INIS)

We study the production of three gauge bosons (W"+W"-Z"0 and W"+W"-#gamma#) at the next generation of linear e"+e"- colliders operating in the #gamma##gamma# mode. We analyze the total cross sections as well as several kinematical distributions of the final state particles. We find out that a linear e"+e"- machine operating in the #gamma##gamma# mode will produce 5--10 times more three-gauge-boson states compared to the standard e"+e"- mode at high energies.

CERN Document Server

The LHC is designed to provide proton beams of 7 TeV and nominal luminosity of 10**34 cm**-2s**-1. This objective is achieved at an affordable cost by pushing all major collider components to the limits of technology, by upgrading the existing CERN accelerators and infrastructure, and by involving the technical expertise, resources and dedication of accelerator laboratories world-wide. Following a decade of intensive R&D and technical validation of major collider systems, the LHC construction is now fully underway. Major industrial contracts have been awarded and are in execution for the procurement of the magnet, cryogenics and other systems. In this report, the status of the design and construction of the major LHC systems is presented.

Energy Technology Data Exchange (ETDEWEB)

We have studied the signals for a heavy Higgs boson in the processes {gamma}{gamma}{yields}WWWW, and {gamma}{gamma}{yields}WWZZ at a photon linear collider. The results are based on the first complete tree-level calculation for these reactions. We show that, with a forward ``spectator`` W tag, and a central ``spectator`` W veto to suppress backgrounds from transverse W, Z production, the invariant mass spectrum of central WW, ZZ pairs is sensitive to Higgs bosons with a mass up to 1 TeV in a 2-TeV linear collider. ((orig.)).

CERN Document Server

The top-color assisted technicolor (TC2) mode predicts the existence of a pair of charged top-pions $\\pi^{\\pm}_t$. In this paper, we study the production of the charged top-pions pair $\\pi^{\\pm}_t$ at next generation $\\gamma\\gamma$ colliders. The results show that the production rates can reach the level of $10^2$ fb with reasonable parameter space. With a large number of events and the clean background, the charged top-pion should be observable at the $\\gamma\\gamma$ colliders. Therefore, our studies can help us to search for charged top-pion, and furthermore, to test the TC2 model.

Energy Technology Data Exchange (ETDEWEB)

Power supply ripple at frequencies of 720 Hz and its harmonies is expected to affect the motion of particles in the collider. These ripple frequencies are nearly resonant with the betatron frequencies. To estimate the tolerable ripple levels, we have tracked particles through the complete nonlinear lattice for 10[sup 4] turns with ripple fed from 10 different power stations and including up to 7 different ripple frequencies. We presently estimate that relative ripple amplitudes must be below the 10[sup 8] level for there to be no significant impact on the emittance over the short term.

Energy Technology Data Exchange (ETDEWEB)

In the 1993 running cycle of the Stanford Linear Collider electron spin polarization measurements with a Moller polarimeter at the end of the linac and a Compton polarimeter near the interaction point (IP) indicated a relative polarization loss of up to 20% across the arc. We present calculations of the depolarizing effects where variations in energy, energy spread and transverse emittance as well as changes in orbit and initial spin orientation are taken into account. We compare our results with measurements and conclude that, in standard operating conditions, the relative polarization loss is only 3+/-2%.

International Nuclear Information System (INIS)

We apply and modify the computer codes CAIN(P.Chen, G.Horton-Smith, T.Ohgaki, A.W.Weidemann, K.Yokoya, contributed to Workshop on Gamma-Gamma Colliders, Berkeley, CA, March 28-31, 1994; SLAC-PUB-6583.) and GUINEAPIG(D.Schulte (DESY), unpublished.) to make detailed studies of the beam-beam interaction in the SLAC design for a future linear collider (NLC), as well as to the proposed SLC2000 project. Using realistic beam distributions, we present simulations related to the tuning and optimization of luminosity in SLC2000 and NLC.

ScienceCinema

...english uh ? that's quite motor ...

CERN Document Server

We present a set of structural parameters for the central parts of 57 early-type galaxies observed with the Planetary Camera of the Hubble Space Telescope. These parameters are based on a new empirical law that successfully characterizes the centers of early type galaxies. This empirical law assumes that the surface brightness profile is a combination of two power laws with different slopes gamma and beta for the inner and outer regions. Conventional structural parameters such as core radius and central surface brightness are replaced by break radius r_b, where the transition between power-law slopes takes place, and surface brightness mu_b at that radius. An additional parameter alpha describes the sharpness of the break. The structural parameters are derived using a chi-squared minimization process applied to the mean surface brightness profiles. The resulting model profiles generally give very good agreement to the observed profiles out to ...

CERN Document Server

We present deep optical long-slit spectra of 17 edge-on spiral galaxies of intermediate to late morphological type, mostly parallel to their major axes and in a few cases parallel to the minor axes.The line-of-sight stellar kinematics are obtained from the stellar absorption lines using the improvedc ross-correlation technique. In general, the stellar kinematics are regular and can be traced well into the disc-dominated region. The mean stellar velocity curves are far from solid-body, indicating that the effect of dust extinction is not large. The line-of-sight stellar disc velocity dispersion correlates with the galaxy maximum rotational velocity, but detailed modeling is necessary to establish whether this represents a physical relation. In four spirals with a boxy- or peanut-shaped bulge we are able to detect asymmetric velocity distributions, having a common signature with projected radius in the mean line-of-sight velocity and the $h_{3}$ ...

CERN Document Server

We discuss the estimation of galaxy correlation properties in several volume limited samples, in different sky regions, obtained from the Fourth Data Release of the Sloan Digital Sky Survey. The small scale properties are characterized through the determination of the nearest neighbor probability distribution. By using a very conservative statistical analysis, in the range of scales [0.5,~30] Mpc/h we detect power-law correlations in the conditional density in redshift space, with an exponent \\gamma=1.0 \\pm 0.1. This behavior is stable in all different samples we considered thus it does not depend on galaxy luminosity. In the range of scales [~30,~100] Mpc/h we find evidences for systematic unaveraged fluctuations and we discuss in detail the problems induced by finite volume effects on the determination of the conditional density. We conclude that in such range of scales there is an evidence for a smaller power-law index of the conditional ...

CERN Document Server

Ultra-luminous infrared galaxies are among the most luminous objects in the local universe and are thought to be powered by intense star formation. It has been shown that in these objects the rotational spectral lines of molecular hydrogen observed at mid-infrared wavelengths are not affected by dust obscuration, leaving unresolved the source of excitation of this emission. Here I report an analysis of archival Spitzer Space Telescope data on ultra-luminous infrared galaxies and demonstrate that star formation regions are buried inside optically thick clouds of gas and dust, so that dust obscuration affects star-formation indicators but not molecular hydrogen. I thereby establish that the emission of H_2 is not co-spatial with the buried starburst activity and originates outside the obscured regions. This is rather surprising in light of the standard view that H_2 emission is directly associated with star-formation activity. Instead, I propose ...

CERN Document Server

We compare N-body simulations of isolated galaxies performed in both frameworks of modified Newtonian dynamics (MOND) and Newtonian gravity with dark matter (DM). We have developed a multigrid code able to efficiently solve the modified Poisson equation derived from the Lagrangian formalism AQUAL. We take particular care of the boundary conditions that are a crucial point in MOND. The 3-dimensional dynamics of initially identical stellar discs is studied in both models. In Newtonian gravity the live DM halo is chosen to fit the rotation curve of the MOND galaxy. For the same value of the Toomre parameter (Q_T), galactic discs in MOND develop a bar instability sooner than in the DM model. In a second phase the MOND bars weaken while the DM bars continue to grow by exchanging angular momentum with the halo. The bar pattern speed evolves quite differently in the two models: there is no dynamical friction on the MOND bars so they keep a constant ...

CERN Document Server

If high-redshift QSOs are ejected from the nuclei of low-redshift galaxies, as some have claimed, a large portion of their redshift must be intrinsic (non-Doppler). If these intrinsic components have preferred values, redshifts will tend to cluster around these preferred values and produce peaks in the redshift distribution. Doppler ejection and Hubble flow components will broaden each peak. Because ejection velocities are randomly directed and Hubble flow components are always positive, in this model all peaks are expected to show an asymmetry, extending further out in the red wing. If peaks are present showing this predicted asymmetry, it can lead directly to an estimate of quasar distances. Using two quasar samples, one with high redshifts and one with low, it is shown here that not only do all peaks in these two redshift distributions occur at previously predicted preferred values, they also all show the predicted extra extension in the red wing. For the low ...

CERN Document Server

Non-axisymmetric forces are presented for 107 spiral galaxies using the 2 Micron All Sky Survey (2MASS) images. We apply both Cartesian integration and a polar grid integration utilizing a limited number of azimuthal Fourier components of density. We found that bar strength is independent of the method used to evaluate the gravitational potential. However, the polar method is more suitable for weak and noisy images. Bar strength was found to be sensitive to the Hubble-type dependent scale height of the disk, which has been ignored in the previous studies. On the other hand, the method is rather insensitive to the vertical model of the disk, as long as a same vertical dispersion is assumed, or to the boxy/peanut shaped structure, studied in terms of non-constant vertical scale height along the disk. In the near-IR most galaxies in our sample show non-axisymmetric forces in some level, and 40 percent of them have bars in a sense that they have ...

Energy Technology Data Exchange (ETDEWEB)

We create realistic, full-sky, half-arcminute resolution simulations of the microwave sky matched to the most recent astrophysical observations. The primary purpose of these simulations is to test the data reduction pipeline for the Atacama Cosmology Telescope (ACT) experiment; however, we have widened the frequency coverage beyond the ACT bands and utilized the easily accessible HEALPix map format to make these simulations applicable to other current and near future microwave background experiments. Some of the novel features of these simulations are that the radio and infrared galaxy populations are correlated with the galaxy cluster and group populations, the primordial microwave background is lensed by the dark matter structure in the simulation via a ray-tracing code, the contribution to the thermal and kinetic Sunyaev-Zel'dovich (SZ) signals from galaxy clusters, groups, and the intergalactic medium has been ...

International Nuclear Information System (INIS)

We report on the discovery of kinematic shock signatures associated with a localized radio jet interaction in the merging Seyfert galaxy NGC 5929. We explore the velocity-dependent ionization structure of the gas and find that low-ionization gas at the interaction site is significantly more disturbed than high-ionization gas, which we attribute to a local enhancement of shock ionization due to the influence of the jet. The characteristic width of the broad low-ionization emission is consistent with shock velocities predicted from the ionization conditions of the gas. We interpret the relative prominence of shocks to the high density of gas in the nuclear environment of the galaxy and place some constraints of their importance as feedback mechanisms in Seyferts.

Energy Technology Data Exchange (ETDEWEB)

The third list of objects in the Second Byurakan Spectral Sky Survey is presented. The list contains 94 objects and 12 blue stars. The data given include the equatorial coordinates to within a minute of arc for the epoch 1950, the angular dimensions in seconds of arc, and visual estimates of the blue apparent magnitude B. The objects are described, giving their morphological and spectral features and approximate values of the red shifts of the galaxies. The distribution of the objects in the survey region, which is centered on right ascension 08h00m, declination +59 deg 00 arcmin, with respect to their types is given. Six close binary systems are found among the selected galaxies.

CERN Document Server

The next decade promises an observational revolution which will change cosmology forever. The precise measurement of the angular anisotropy of the cosmic microwave background should specify to a few percent all of the parameters of the cosmological model which effect astrophysics. The growth of structure will then be determined (but not yet observed) until gravitational collapse becomes highly non-linear and stars, galaxies and active galactic nuclei (AGN) form. These processes are hard to model with basic physics because they are complex and allow a rich variety of expression. Instead observations will determine when the first stars and quasars formed, and how and when galaxies assembled. If we can reconcile the numerous contradictions which characterize the subject today, cosmology will become a mature subject, founded on the agreement between detailed, inclusive and realistic models, which make precise predictions, and the wealth of new data ...

Energy Technology Data Exchange (ETDEWEB)

The relative merits and difficlties of the primary and secondry origin hypotheses for the observed cosmic-ray antiprotons, including the new low-energy measurement of Buffington, et al are discussed. We conclude that the cosmic-ray antiproton data may be evidence for antimatter galaxies and baryon symmetric cosmology. The present bar P data are consistent with a primary extragalactic component having /p /equiv 1+/- 3.2/0.7x10 to the -4 independent of energy. We propose that the primary extragalactic cosmic ray antiprotons are most likely from active galaxies and that expected disintegration of bar alpha/alpha ban alpha/alpha. We further predict a value for ban alpha/alpha /equiv 10 to the -5, within range of future cosmic ray detectors.

CERN Document Server

Prompted by work on the buckling instability in barred spiral galaxies, much effort has been devoted lately to the study of boxy/peanut-shaped (B/PS) bulges. Here, we present new bar diagnostics for edge-on spiral galaxies based on periodic orbits calculations and hydrodynamical simulations. Both approaches provide reliable ways to identify bars and their orientations in edge-on systems. We also present the results of an observational search for bars in a large sample of edge-on spirals with and without B/PS bulges. We show that most B/PS bulges are due to the presence of a thick bar viewed edge-on while only a few may be due to accretion. This strongly supports the bar-buckling mechanism for the formation of B/PS bulges.

Energy Technology Data Exchange (ETDEWEB)

The authors analyze the consequences of models of structure formation for higher-order (n-point) galaxy correlation functions in the mildly non-linear regime. Several variations of the standard {Omega} = 1 cold dark matter model with scale-invariant primordial perturbations have recently been introduced to obtain more power on large scales, R{sub p} {approximately}20 h{sup {minus}1} Mpc, e.g., low-matter-density (non-zero cosmological constant) models, {open_quote}tilted{close_quote} primordial spectra, and scenarios with a mixture of cold and hot dark matter. They also include models with an effective scale-dependent bias, such as the cooperative galaxy formation scenario of Bower, et al. The authors show that higher-order (n-point) galaxy correlation functions can provide a useful test of such models and can discriminate between models with true large-scale power in the density field and those where the ...

International Nuclear Information System (INIS)

Global angular momentum balance suggests that the neutron stars in Be/X-ray binaries are not spinning in equilibrium. This requires an X-ray lifetime ''approx <'' 10"5 yr, and suggests that there are many 'dead' Be/X-ray binaries in the Galaxy. Some of these may be turned up as millisecond radio pulsars with Be star companions. (author).

Energy Technology Data Exchange (ETDEWEB)

The problem on change of deuterium abundance in the process of galactic evolution (star evolution, supernova explosions, nucleosynthesis in supermassive objects) is considered. It is shown that the observable deuterium quantity in the interstellar medium must correspond to its cosmological abundance. This conclusion is independent of the rate of accretion of intergalactic gas by Galaxy. The effect of hypothetical pregalactic active objects on cosmological deuterium is small. It is poind out that observations of interstellar deuterium in absorbtion at lambda=91.6 cm are significant.

Energy Technology Data Exchange (ETDEWEB)

The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic ray antiprotons, including the low energy measurement of Buffington, were examined. It is concluded that the cosmic ray antiproton data may be strong evidence for antimatter galaxies and baryon symmetric cosmology. The present antiproton data are consistent with a primary extragalactic component having antiproton/proton approximately equal to .0032 + or - 0.7.

International Nuclear Information System (INIS)

In this thesis, the potential to discover supersymmetric signatures in both e"+e"- and #gamma##gamma# colliders evaluated with a Monte Carlo analysis, is discussed. The analysis was focused on the detection of muons, essentially. First, we study the detection of #mu#"+_R#mu#"-_R in e"-e"+ collisions, whose purpose is the measurement of the #mu#_R mass. It was found that an uncertainty of 0.11 GeV (stat) can be achieved. Under the assumption of the real conditions of the ILC photon collider, a study covering the detection of #mu#"+_R#mu#"-_R and #mu#"+_L#mu#"-_L pairs for #sq root#(s_e_"-_e_"+)=0.5 and 0.6 TeV was performed. According to the simulation, a statistical error for the branching ratios of #mu#"#+-#_L#->##chi#"0_1#mu#"#+-# of 0.98% and #mu#"#+-#_L#->##chi#"0_2#mu#"#+-# of 3.97% can be reached. In order to judge the Monte Carlo results, we have used a technique based on a multidimensional fit to evaluate the impact of the ...

International Nuclear Information System (INIS)

We discuss various reactions at future e"+e"- and #gamma##gamma# colliders involving real (beamstrahlung or backscattered laser) or quasi-real (bremsstrahlung) photons in the initial state and hadrons in the final state. The production of two central jets with large transverse momentum p_T is described in some detail; we give distributions for the rapidity and p_T of the jets as well as the di-jet invariant mass, and discuss the relative importance of various initial state configurations and the uncertainties that arise from the at present rather poor knowledge of the parton content of the photon. We also present results for 'mono-jet' production where one jet goes down a beam pipe, for the production of charm, bottom and top quarks, and for single production of W and Z bosons. Where appropriate, the two-photon processes are compared with annihilation reactions leading to similar final states. We also argue that the behaviour of the total inelastic #gamma##gamma# ...

CERN Document Server

We study neutral and charged Higgs boson production in association with stop and sbottom squarks at the Large Hadron Collider, within the supergravity inspired minimal supersymmetric standard model We study neutral and charged Higgs boson production in association with stop and sbottom squarks at the Large Hadron Collider, within the Supergravity inspired Minimal Supersymmetric Standard Model. The phenomenological relevance of such reactions is twofold. Firstly, they constitute a novel production mechanism of Higgs particles, either through a decay of a heavier (anti)squark into a lighter one or via a Higgs bremsstrahlung process. Secondly, their production rates are extremely sensitive to the values assumed by the five input parameters of the model, this possibly allowing one to put stringent constraints on the latter. After an exhaustive scan of the parameter space, we find that the majority of such processes could be detectable at high ...

International Nuclear Information System (INIS)

A future e"-e"+ (electron-positron) linear collider can be configured with perhaps minimal modification to serve as an #gamma#-#gamma# (gamma-gamma) or a e"--#gamma# collider. This is accomplished by Compton-backscattering low energy photons (from a laser source) off of the high-energy electron beams prior to the crossing of the electron beams. However, to be competitive with the e"-e"+ configuration, the luminosity cannot be compromised in the process. This requires that the laser source deliver a sufficient number of photons per pulse with a pulse format and rate matching that of the electron beams. As it turns out, this requires an average optical power of 5 to 15 kW from the laser which is beyond the current state of the art. In this paper, the authors address how to generate the required pulse format and how the high average power requirement can be met with conventional laser technology. They also address concerns about the survivability ...

Energy Technology Data Exchange (ETDEWEB)

A future e{sup {minus}}e{sup +} (electron-positron) linear collider can be configured with perhaps minimal modification to serve as an {gamma}-{gamma} (gamma-gamma) or a e{sup {minus}}-{gamma} collider. This is accomplished by Compton-backscattering low energy photons (from a laser source) off of the high-energy electron beams prior to the crossing of the electron beams. However, to be competitive with the e{sup {minus}}e{sup +} configuration, the luminosity cannot be compromised in the process. This requires that the laser source deliver a sufficient number of photons per pulse with a pulse format and rate matching that of the electron beams. As it turns out, this requires an average optical power of 5 to 15 kW from the laser which is beyond the current state of the art. In this paper, the authors address how to generate the required pulse format and how the high average power requirement can be met with conventional laser technology. They ...

Science.gov (United States)

This presentation from the 2006 PTEC Conference presents education research on topics in thermodynamics. Student responses to conceptual thermodynamics questions, and the conceptions they reveal, are presented. Tutorial materials developed to help students gain a better understanding of the topic are also presented.

Science.gov (United States)

An understanding of the mechanism of generation of Lg from underground nuclear explosions is essential for seismic monitoring and source discrimination. Near-source scattering of explosion-generated Rg into S appears to be responsible for the low-frequenc...

Science.gov (United States)

Understanding the detailed mechanics of these systems and their place in the general picture of binary star evolution are the dual objectives of this ...

Norwegian Open Research Archives (NORA)

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Science.gov (United States)

Feb 11, 1997 ... Dr. Baldwin's research focuses on understanding the mechanisms of skeletal and cardiac muscle adaptations to hormonal and activity ...

British Library Electronic Table of Contents (United Kingdom)

Purpose - The article shares insights from a program that was developed to address burnout, compassion fatigue and vicarious trauma. The program works from the premise that people and organizations thrive when they have shared values and common understandings. Design/methodology/approach - The approach draws together reflection at the organizational and person levels. Connecting business ethics and organizational analysis, improving understanding of the body's energy as well as inter-cultural understanding are all achievable while adopting the resilience development methods. Findings - The article concludes that reflective practice through the tools used on the program enhances understanding of the challenges faced by organizations and the individuals involved. It provides creative routes ...

Energy Technology Data Exchange (ETDEWEB)

The superconducting Tevatron accelerator at Fermi National Accelerator Laboratory (Fermilab) has surpassed twenty years of operation. The Tevatron is still the highest energy particle accelerator in the world and will remain so until the commissioning of the LHC in Europe later this decade. The Tevatron has operated in a Fixed Target mode, accelerating a proton beam into stationary targets/detectors, as well as a Colliding Beam mode, continuously colliding counter rotating beams of protons and antiprotons. Upon completion, the Tevatron cryogenic system became the world's largest helium refrigeration system. In 1993, the Tevatron cryogenic system was given the designation of International Historic Mechanical Engineering Landmark by the American Society of Mechanical Engineers. The operational history, experiences and statistics of the Tevatron, with an emphasis on the cryogenic system, is presented. Improvements, upgrades and current ...

Energy Technology Data Exchange (ETDEWEB)

This Report includes copies of transparencies and notes from the presentations made at the Center for Accelerator Physics at Brookhaven National Laboratory Editing and changes to the authors` contributions in this Report were made only to fulfill the publication requirements. This volume includes notes and transparencies on nine presentations: ``The Energy Exchange and Efficiency Consideration in Klystrons``, ``Some Properties of Microwave RF Sources for Future Colliders + Overview of Microwave Generation Activity at the University of Maryland``, ``Field Quality Improvements in Superconducting Magnets for RHIC``, ``Hadronic B-Physics``, ``Spiking Pulses from Free Electron Lasers: Observations and Computational Models``, ``Crystalline Beams in Circular Accelerators``, ``Accumulator Ring for AGS & Recent AGS Performance``, ``RHIC Project Machine Status``, and ``Gamma-Gamma Colliders.``

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We study CP-violating phenomena in the production, mixing and decay of a coupled system of CP-violating neutral Higgs bosons at {gamma}{gamma} colliders, assuming a Minimal Supersymmetric Standard Model (MSSM) Higgs sector in which CP violation is radiatively induced by phases in the soft supersymmetry-breaking gaugino masses and third-generation trilinear squark couplings. We discuss CP asymmetries in the production and decays of {mu}{sup +}{mu}{sup -}, {tau}{sup +}{tau}{sup -}, b-bar b and t-bar t pairs. We find large asymmetries when two (or all three) neutral Higgs bosons are nearly degenerate with mass differences comparable to their decay widths, as happens naturally in the CP-violating MSSM for values of tan{beta}-bar 5 (30) and large (small) charged Higgs-boson masses.

Energy Technology Data Exchange (ETDEWEB)

We present the effects of heavy CP-even (H) and CP-odd (A) Higgs bosons on the production cross section of the process {gamma}{gamma}{yields}tt at the energy around the mass poles of the Higgs bosons. It is found that interference between H and A with small mass gap, as well as the ones between Higgs bosons and continuum, contributes to the cross section, if the photon beams are polarized and if we observe the helicity of the top quarks. It is demonstrated in the framework of the minimal supersymmetric extension of the standard model that the H and A contributions can be sizable at future {gamma}{gamma} colliders for small values of tan {beta}. The methods to measure the CP-parity of the Higgs boson are also presented. The statistical significance of detecting the Higgs signals and measuring the Higgs CP-parity is evaluated. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Possible anomalous top-quark couplings induced by SU(2)xU(1) gauge-invariant dimension-6 effective operators were studied in the process of ttbar productions and decays at polarized {gamma}{gamma} colliders. Two CP-violating asymmetries, a linear-polarization asymmetry and a circular-polarization asymmetry, were computed including both non-standard ttbar{gamma} and {gamma}{gamma}H couplings. An optimal-observable analysis for the process {gamma}{gamma}{yields}ttbar{yields}l{sup {+-}} was performed in order to estimate the precision for determination of all relevant non-standard couplings, including the anomalous tbW coupling.

International Nuclear Information System (INIS)

We analyze the potential of the e"+e"- linear colliders, operating in the e#gamma# and #gamma##gamma# modes, to probe anomalous quartic vector-boson interactions through the multiple production of W's and Z's. We examine all SU(2)_L(circle times)U(1)_Y chiral operators of order p"4 that lead to new four-gauge-boson interactions but do not alter trilinear vertices. We show that the e#gamma# and #gamma##gamma# modes are able not only to establish the existence of a strongly interacting symmetry breaking sector but also to probe for anomalous quartic couplings of the order of 10"-"2 at 90% C.L. Moreover, the information gathered in the e#gamma# mode can be used to reduce the ambiguities of the e"+e"- mode.

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