1,839 research outputs found

    Cosmological constraints from the convergence 1-point probability distribution

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    We examine the cosmological information available from the 1-point probability distribution (PDF) of the weak-lensing convergence field, utilizing fast L-PICOLA simulations and a Fisher analysis. We find competitive constraints in the Ωm\Omega_m-σ8\sigma_8 plane from the convergence PDF with 188 arcmin2188\ arcmin^2 pixels compared to the cosmic shear power spectrum with an equivalent number of modes (<886\ell < 886). The convergence PDF also partially breaks the degeneracy cosmic shear exhibits in that parameter space. A joint analysis of the convergence PDF and shear 2-point function also reduces the impact of shape measurement systematics, to which the PDF is less susceptible, and improves the total figure of merit by a factor of 232-3, depending on the level of systematics. Finally, we present a correction factor necessary for calculating the unbiased Fisher information from finite differences using a limited number of cosmological simulations.Comment: 10 pages, 5 figure

    Isobaric multiplet mass equation in the A=31A=31 T=3/2T = 3/2 quartets

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    The observed mass excesses of analog nuclear states with the same mass number AA and isospin TT can be used to test the isobaric multiplet mass equation (IMME), which has, in most cases, been validated to a high degree of precision. A recent measurement [Kankainen et al., Phys. Rev. C 93 041304(R) (2016)] of the ground-state mass of 31^{31}Cl led to a substantial breakdown of the IMME for the lowest A=31,T=3/2A = 31, T = 3/2 quartet. The second-lowest A=31,T=3/2A = 31, T = 3/2 quartet is not complete, due to uncertainties associated with the identity of the 31^{31}S member state. Using a fast 31^{31}Cl beam implanted into a plastic scintillator and a high-purity Ge γ\gamma-ray detection array, γ\gamma rays from the 31^{31}Cl(βγ)(\beta\gamma)31^{31}S sequence were measured. Shell-model calculations using USDB and the recently-developed USDE interactions were performed for comparison. Isospin mixing between the 31^{31}S isobaric analog state (IAS) at 6279.0(6) keV and a nearby state at 6390.2(7) keV was observed. The second T=3/2T = 3/2 state in 31^{31}S was observed at Ex=7050.0(8)E_x = 7050.0(8) keV. Isospin mixing in 31^{31}S does not by itself explain the IMME breakdown in the lowest quartet, but it likely points to similar isospin mixing in the mirror nucleus 31^{31}P, which would result in a perturbation of the 31^{31}P IAS energy. USDB and USDE calculations both predict candidate 31^{31}P states responsible for the mixing in the energy region slightly above Ex=6400E_x = 6400 keV. The second quartet has been completed thanks to the identification of the second 31^{31}S T=3/2T = 3/2 state, and the IMME is validated in this quartet

    Heavy Quarkonium Potential Model and the 1P1{}^1P_1 State of Charmonium

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    A theoretical explanation of the observed splittings among the P~states of charmonium is given with the use of a nonsingular potential model for heavy quarkonia. We also show that the recently observed mass difference between the center of gravity of the 3PJ{}^3P_J states and the 1P1{}^1P_1 state of ccˉc\bar{c} does not provide a direct test of the color hyperfine interaction in heavy quarkonia. Our theoretical value for the mass of the 1P1{}^1P_1 state is in agreement with the experimental result, and its E1 transition width is 341.8~keV. The mass of the ηc\eta_c' state is predicted to be 3622.3~MeV.Comment: 15 page REVTEX documen

    Brown dwarf census with the Dark Energy Survey year 3 data and the thin disc scale height of early L types

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    27 pages, 18 figuresIn this paper we present a catalogue of 11 745 brown dwarfs with spectral types ranging from L0 to T9, photometrically classified using data from the Dark Energy Survey (DES) year 3 release matched to the Vista Hemisphere Survey (VHS) DR3 and Wide-field Infrared Survey Explorer (WISE) data, covering ≈2400 deg2 up to iAB = 22. The classification method follows the same phototype method previously applied to SDSS-UKIDSS-WISE data. The most significant difference comes from the use of DES data instead of SDSS, which allow us to classify almost an order of magnitude more brown dwarfs than any previous search and reaching distances beyond 400 pc for the earliest types. Next, we also present and validate the GalmodBD simulation, which produces brown dwarf number counts as a function of structural parameters with realistic photometric properties of a given survey. We use this simulation to estimate the completeness and purity of our photometric LT catalogue down to iAB = 22, as well as to compare to the observed number of LT types. We put constraints on the thin disc scale height for the early L (L0–L3) population to be around 450 pc, in agreement with previous findings. For completeness, we also publish in a separate table a catalogue of 20 863 M dwarfs that passed our colour cut with spectral types greater than M6. Both the LT and the late M catalogues are found at DES release page https://des.ncsa.illinois.edu/releases/other/y3-mlt.Peer reviewedFinal Published versio

    Review of Animal Rights Without Liberation: Applied Ethics and Human Obligations

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    This submission is a book review for Alasdair Cochrane\u27s Animal Rights Without Liberation: Applied Ethics and Human Obligation

    Chemical Abundance Analysis of Tucana III, the Second rr-process Enhanced Ultra-Faint Dwarf Galaxy

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    We present a chemical abundance analysis of four additional confirmed member stars of Tucana III, a Milky Way satellite galaxy candidate in the process of being tidally disrupted as it is accreted by the Galaxy. Two of these stars are centrally located in the core of the galaxy while the other two stars are located in the eastern and western tidal tails. The four stars have chemical abundance patterns consistent with the one previously studied star in Tucana III: they are moderately enhanced in rr-process elements, i.e. they have + \approx +0.4 dex. The non-neutron-capture elements generally follow trends seen in other dwarf galaxies, including a metallicity range of 0.44 dex and the expected trend in α\alpha-elements, i.e., the lower metallicity stars have higher Ca and Ti abundance. Overall, the chemical abundance patterns of these stars suggest that Tucana III was an ultra-faint dwarf galaxy, and not a globular cluster, before being tidally disturbed. As is the case for the one other galaxy dominated by rr-process enhanced stars, Reticulum II, Tucana III's stellar chemical abundances are consistent with pollution from ejecta produced by a binary neutron star merger, although a different rr-process element or dilution gas mass is required to explain the abundances in these two galaxies if a neutron star merger is the sole source of rr-process enhancement.Comment: 18 pages, 10 figures; accepted by Ap
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