41,844 research outputs found

    The Stellar Mass Fundamental Plane: The virial relation and a very thin plane for slow-rotators

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    Early-type galaxies -- slow and fast rotating ellipticals (E-SRs and E-FRs) and S0s/lenticulars -- define a Fundamental Plane (FP) in the space of half-light radius ReR_e, enclosed surface brightness IeI_e and velocity dispersion σe\sigma_e. Since IeI_e and σe\sigma_e are distance-independent measurements, the thickness of the FP is often expressed in terms of the accuracy with which IeI_e and σe\sigma_e can be used to estimate sizes ReR_e. We show that: 1) The thickness of the FP depends strongly on morphology. If the sample only includes E-SRs, then the observed scatter in ReR_e is ∼16%\sim 16\%, of which only ∼9%\sim 9\% is intrinsic. Removing galaxies with M∗<1011M⊙M_*<10^{11}M_\odot further reduces the observed scatter to ∼13%\sim 13\% (∼4%\sim 4\% intrinsic). The observed scatter increases to the ∼25%\sim 25\% usually quoted in the literature if E-FRs and S0s are added. If the FP is defined using the eigenvectors of the covariance matrix of the observables, then the E-SRs again define an exceptionally thin FP, with intrinsic scatter of only 5%5\% orthogonal to the plane. 2) The structure within the FP is most easily understood as arising from the fact that IeI_e and σe\sigma_e are nearly independent, whereas the Re−IeR_e-I_e and Re−σeR_e-\sigma_e correlations are nearly equal and opposite. 3) If the coefficients of the FP differ from those associated with the virial theorem the plane is said to be `tilted'. If we multiply IeI_e by the global stellar mass-to-light ratio M∗/LM_*/L and we account for non-homology across the population by using S\'ersic photometry, then the resulting stellar mass FP is less tilted. Accounting self-consistently for M∗/LM_*/L gradients will change the tilt. The tilt we currently see suggests that the efficiency of turning baryons into stars increases and/or the dark matter fraction decreases as stellar surface brightness increases.Comment: 13 pages, 9 figures, 3 tables, accepted for publication in MNRA

    On the difference between proton and neutron spin-orbit splittings in nuclei

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    The latest experimental data on nuclei at 132^{132}Sn permit us for the first time to determine the spin-orbit splittings of neutrons and protons in identical orbits in this neutron-rich doubly-magic region and compare the case to that of 208^{208}Pb. Using the new results, which are now consistent for the two neutron-rich doubly magic regions, a theoretical analysis defines the isotopic dependence of the mean field spin-orbit potential and leads to a simple explicit expression for the difference between the spin-orbit splittings of neutrons and protons. The isotopic dependence is explained in the framework of different theoretical approaches.Comment: 8 pages, revte

    Lateral Casimir force beyond the Proximity Force Approximation

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    We argue that the appropriate variable to study a non trivial geometry dependence of the Casimir force is the lateral component of the Casimir force, which we evaluate between two corrugated metallic plates outside the validity of the Proximity Force Approximation (PFA). The metallic plates are described by the plasma model, with arbitrary values for the plasma wavelength, the plate separation and the corrugation period, the corrugation amplitude remaining the smallest length scale. Our analysis shows that in realistic experimental situations the Proximity Force Approximation overestimates the force by up to 30%.Comment: 4 pages. Identical to v1, which was accidentally replaced by a different paper (quant-ph/0610026

    Probing the massive star forming environment - a multiwavelength investigation of the filamentary IRDC G333.73+0.37

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    We present a multiwavelength study of the filamentary infrared dark cloud (IRDC) G333.73+0.37. The region contains two distinct mid-infrared sources S1 and S2 connected by dark lanes of gas and dust. Cold dust emission from the IRDC is detected at seven wavelength bands and we have identified 10 high density clumps in the region. The physical properties of the clumps such as temperature: 14.3-22.3 K and mass: 87-1530 M_sun are determined by fitting a modified blackbody to the spectral energy distribution of each clump between 160 micron and 1.2 mm. The total mass of the IRDC is estimated to be $~4700 M_sun. The molecular line emission towards S1 reveals signatures of protostellar activity. Low frequency radio emission at 1300 and 610 MHz is detected towards S1 (shell-like) and S2 (compact morphology), confirming the presence of newly formed massive stars in the IRDC. Photometric analysis of near and mid-infrared point sources unveil the young stellar object population associated with the cloud. Fragmentation analysis indicates that the filament is supercritical. We observe a velocity gradient along the filament, that is likely to be associated with accretion flows within the filament rather than rotation. Based on various age estimates obtained for objects in different evolutionary stages, we attempt to set a limit to the current age of this cloud.Comment: 26 pages, 20 figures, accepted by Ap

    Spontaneous formation of optically induced surface relief gratings

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    A model based on Fick's law of diffusion as a phenomenological description of the molecular motion, and on the coupled mode theory, is developped to describe single-beam surface relief grating formation in azopolymers thin films. It allows to explain the mechanism of spontaneous patterning, and self-organization. It allows also to compute the surface relief profile and its evolution in time with good agreement with experiments

    Synchronous OEIC integrating receiver for ORGA applications

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    This work presents a monolithically integrated synchronous optical receiver fabricated in a standard 0.35 mu m CMOS process. The receiver consists of a regenerative latch acting as a sense amplifier; two highly effective, low-capacitance pin photodiodes connected to its output nodes (one of them blocked to the light); and an adjustable reference current to compensate the dynamic offset created by the asymmetries between the parasitic capacitances of the photodiodes. For lambda = 635 nm, a sensitivity of -25.8 dBm, -26.0 dBm, and -28.4dBm is obtained, respectively, for 400 Mbit/s, 350 Mbit/s, and 250 Mbit/s (BER = 10(-9)). The power consumption is 670 mu W, which translates to an energy efficiency of 1.7 pJ/bit at 400 Mbit/s

    Analysis of the D^+ → K^-π^+e^+ν_e decay channel

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    Using 347.5  fb^(-1) of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244×10^3 signal events for the D^+ → K^-π^+e^+ν_e decay channel are analyzed. This decay mode is dominated by the K̅ ^*(892)^0 contribution. We determine the K̅ ^*(892)^0 parameters: m_(K^*(892)^0)=(895.4±0.2±0.2)  MeV/c^2, Γ_(K^*(892)^0)=(46.5±0.3±0.2)  MeV/c^2, and the Blatt-Weisskopf parameter r_(BW) =2.1±0.5±0.5  (GeV/c)^-1, where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q^2 = 0 (r_V = ^(V(0))/_(A1(0)) = 1.463 ± 0.017 ± 0.031, r_2 = _(A1(0)) ^(A2(0))= 0.801±0.020±0.020) and the value of the axial-vector pole mass parametrizing the q^2 variation of A_1 and A_2: m_A=(2.63±0.10±0.13)  GeV/c^2. The S-wave fraction is equal to (5.79±0.16±0.15)%. Other signal components correspond to fractions below 1%. Using the D^+ → K^-π^+π^+ channel as a normalization, we measure the D^+ semileptonic branching fraction: B(D^+ → K^-π^+e^+ν_e)=(4.00±0.03±0.04±0.09)×10^(-2), where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A_1 at q^2=0: A_1(0)=0.6200±0.0056±0.0065±0.0071. Fixing the P-wave parameters, we measure the phase of the S wave for several values of the Kπ mass. These results confirm those obtained with Kπ production at small momentum transfer in fixed target experiments

    Study of B → Xγ decays and determination of |V_(td)/V_(ts)|

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    Using a sample of 471×10^6 BB̅[overbar] events collected with the BABAR detector, we study the sum of seven exclusive final states B→X_(s(d))γ, where X_(s(d)) is a strange (nonstrange) hadronic system with a mass of up to 2.0  GeV/c^2. After correcting for unobserved decay modes, we obtain a branching fraction for b→dγ of (9.2±2.0(stat)±2.3(syst))×10^(-6) in this mass range, and a branching fraction for b→sγ of (23.0±0.8(stat)±3.0(syst))×10^(-5) in the same mass range. We find B[script](b→dγ)/B[script](b→sγ)=0.040±0.009(stat)±0.010(syst), from which we determine |V_(td)/V_(ts)|=0.199±0.022(stat)±0.024(syst)±0.002(th)
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