11,507 research outputs found

    Spatially resolved spectroscopy of Coma cluster early-type galaxies IV. Completing the dataset

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    The long-slit spectra obtained along the minor axis, offset major axis and diagonal axis are presented for 12 E and S0 galaxies of the Coma cluster drawn from a magnitude-limited sample studied before. The rotation curves, velocity dispersion profiles and the H_3 and H_4 coefficients of the Hermite decomposition of the line of sight velocity distribution are derived. The radial profiles of the Hbeta, Mg, and Fe line strength indices are measured too. In addition, the surface photometry of the central regions of a subsample of 4 galaxies recently obtained with Hubble Space Telescope is presented. The data will be used to construct dynamical models of the galaxies and study their stellar populations.Comment: 40 pages, 7 figures, 6 tables. Accepted for publication in ApJ

    Model of supersymmetric quantum field theory with broken parity symmetry

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    Recently, it was observed that self-interacting scalar quantum field theories having a non-Hermitian interaction term of the form g(iϕ)2+δg(i\phi)^{2+\delta}, where δ\delta is a real positive parameter, are physically acceptable in the sense that the energy spectrum is real and bounded below. Such theories possess PT invariance, but they are not symmetric under parity reflection or time reversal separately. This broken parity symmetry is manifested in a nonzero value for , even if δ\delta is an even integer. This paper extends this idea to a two-dimensional supersymmetric quantum field theory whose superpotential is S(ϕ)=ig(iϕ)1+δ{\cal S}(\phi)=-ig(i\phi)^{1+\delta}. The resulting quantum field theory exhibits a broken parity symmetry for all δ>0\delta>0. However, supersymmetry remains unbroken, which is verified by showing that the ground-state energy density vanishes and that the fermion-boson mass ratio is unity.Comment: 20 pages, REVTeX, 11 postscript figure

    Scalar Quantum Field Theory with Cubic Interaction

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    In this paper it is shown that an i phi^3 field theory is a physically acceptable field theory model (the spectrum is positive and the theory is unitary). The demonstration rests on the perturbative construction of a linear operator C, which is needed to define the Hilbert space inner product. The C operator is a new, time-independent observable in PT-symmetric quantum field theory.Comment: Corrected expressions in equations (20) and (21

    Asymptotic Analysis of the Boltzmann Equation for Dark Matter Relics

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    This paper presents an asymptotic analysis of the Boltzmann equations (Riccati differential equations) that describe the physics of thermal dark-matter-relic abundances. Two different asymptotic techniques are used, boundary-layer theory, which makes use of asymptotic matching, and the delta expansion, which is a powerful technique for solving nonlinear differential equations. Two different Boltzmann equations are considered. The first is derived from general relativistic considerations and the second arises in dilatonic string cosmology. The global asymptotic analysis presented here is used to find the long-time behavior of the solutions to these equations. In the first case the nature of the so-called freeze-out region and the post-freeze-out behavior is explored. In the second case the effect of the dilaton on cold dark-matter abundances is calculated and it is shown that there is a large-time power-law fall off of the dark-matter abundance. Corrections to the power-law behavior are also calculated.Comment: 15 pages, no figure

    Kinematic Structure of Merger Remnants

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    We use numerical simulations to study the kinematic structure of remnants formed from mergers of equal-mass disk galaxies. In particular, we show that remnants of dissipational mergers, which include the radiative cooling of gas, star formation, feedback from supernovae, and the growth of supermassive black holes, are smaller, rounder, have, on average, a larger central velocity dispersion, and show significant rotation compared to remnants of dissipationless mergers. The increased rotation speed of dissipational remnants owes its origin to star formation that occurs in the central regions during the galaxy merger. We have further quantified the anisotropy, three-dimensional shape, minor axis rotation, and isophotal shape of each merger remnant, finding that dissipational remnants are more isotropic, closer to oblate, have the majority of their rotation along their major axis, and are more disky than dissipationless remnants. Individual remnants display a wide variety of kinematic properties. A large fraction of the dissipational remnants are oblate isotropic rotators. Many dissipational, and all of the dissipationless, are slowly rotating and anisotropic. The remnants of gas-rich major mergers can well-reproduce the observed distribution of projected ellipticities, rotation parameter (V/\sigma)*, kinematic misalignments, Psi, and isophotal shapes. The dissipationless remnants are a poor match to this data. Our results support the merger hypothesis for the origin of low-luminosity elliptical galaxies provided that the progenitor disks are sufficiently gas-rich, however our remnants are a poor match to the bright ellipticals that are slowly rotating and uniformly boxy.Comment: 22 pages, 17 figures, accepted to Ap

    LISA Science Results in the Presence of Data Disturbances

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    Each spacecraft in the Laser Interferometer Space Antenna houses a proof mass which follows a geodesic through spacetime. Disturbances which change the proof mass position, momentum, and/or acceleration will appear in the LISA data stream as additive quadratic functions. These data disturbances inhibit signal extraction and must be removed. In this paper we discuss the identification and fitting of monochromatic signals in the data set in the presence of data disturbances. We also present a preliminary analysis of the extent of science result limitations with respect to the frequency of data disturbances

    HI Detection in two Dwarf S0 Galaxies in Nearby Groups: ESO384-016 and NGC 59

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    An \hi survey of 10 dE/dS0 galaxies in the nearby Sculptor and Centaurus A groups was made using the Australia Telescope Compact Array (ATCA). The observed galaxies have accurate distances derived by Jerjen et al (1998; 2000b) using the surface brightness fluctuation technique. Their absolute magnitudes are in the range 9.5>MB>15.3-9.5 > M_B > -15.3. Only two of the ten galaxies were detected at our detection limit (1.0×106\sim 1.0 \times 10^6 \msol for the Centaurus group and 5.3×105\sim 5.3 \times 10^5 \msol for the Sculptor group), the two dS0 galaxies ESO384-016 in the Centaurus A Group and NGC 59 in the Sculptor Group, with \hi masses of 6.0±0.5×1066.0 \pm 0.5 \times 10^6 \msol and 1.4±0.1×1071.4 \pm 0.1 \times 10^7 \msol respectively. Those two detections were confirmed using the Green Bank Telescope. These small \hi reservoirs could fuel future generations of low level star formation and could explain the bluer colors seen at the center of the detected galaxies. Similarly to what is seen with the Virgo dEs, the two objects with \hi appear to be on the outskirt of the groups.Comment: 25 pages (11 figures), accepted by A

    Detection and Quantification of Multi-Analyte Mixtures Using a Single Sensor and Multi-Stage Data-Weighted RLSE

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    This work reports the development and experimental verification of a sensor signal processing technique for online identification and quantification of aqueous mixtures of benzene, toluene, ethylbenzene, xylenes (BTEX) and 1, 2, 4-trimethylbenzene (TMB) at ppb concentrations using time-dependent frequency responses from a single polymer-coated shear-horizontal surface acoustic wave sensor. Signal processing based on multi-stage exponentially weighted recursive leastsquares estimation (EW-RLSE) is utilized for estimating the concentrations of the analytes in the mixture that are most likely to have produced a given sensor response. The initial stages of EW-RLSE are used to eliminate analyte(s) that are erroneously identified as present in the mixture; the final stage of EW-RLSE with the corresponding sensor response model representing the analyte(s) present in the mixture is used to obtain a more accurate quantification result of the analyte(s). The success of this method in identifying and quantifying analytes in real-time with high accuracy using the response of just a single sensor device demonstrates an effective, simpler, lower-cost alternative to a sensor array that includes the advantage of not requiring a complex training protocol

    Lipkin translational-symmetry restoration in the mean-field and energy-density-functional methods

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    Based on the 1960 idea of Lipkin, the minimization of energy of a symmetry-restored mean-field state is equivalent to the minimization of a corrected energy of a symmetry-broken state with the Peierls-Yoccoz mass. It is interesting to note that the "unphysical" Peierls-Yoccoz mass, and not the true mass, appears in the Lipkin projected energy. The Peierls-Yoccoz mass can be easily calculated from the energy and overlap kernels, which allows for a systematic, albeit approximate, restoration of translational symmetry within the energy-density formalism. Analogous methods can also be implemented for all other broken symmetries.Comment: 15 LaTeX pages, 8 eps figures, submitted to Journal of Physics

    Statistical Models on Spherical Geometries

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    We use a one-dimensional random walk on DD-dimensional hyper-spheres to determine the critical behavior of statistical systems in hyper-spherical geometries. First, we demonstrate the properties of such a walk by studying the phase diagram of a percolation problem. We find a line of second and first order phase transitions separated by a tricritical point. Then, we analyze the adsorption-desorption transition for a polymer growing near the attractive boundary of a cylindrical cell membrane. We find that the fraction of adsorbed monomers on the boundary vanishes exponentially when the adsorption energy decreases towards its critical value.Comment: 8 pages, latex, 2 figures in p
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