266 research outputs found

    Pinpointing Cosmic Ray Propagation With The AMS-02 Experiment

    Full text link
    The Alpha Magnetic Spectrometer (AMS-02), which is scheduled to be deployed onboard the International Space Station later this year, will be capable of measuring the composition and spectra of GeV-TeV cosmic rays with unprecedented precision. In this paper, we study how the projected measurements from AMS-02 of stable secondary-to-primary and unstable ratios (such as boron-to-carbon and beryllium-10-to-beryllium-9) can constrain the models used to describe the propagation of cosmic rays throughout the Milky Way. We find that within the context of fairly simple propagation models, all of the model parameters can be determined with high precision from the projected AMS-02 data. Such measurements are less constraining in more complex scenarios, however, which allow for departures from a power-law form for the diffusion coefficient, for example, or for inhomogeneity or stochasticity in the distribution and chemical abundances of cosmic ray sources.Comment: 12 pages, 7 figures, 3 tables, matches published versio

    The Orbital Period of the Ultraluminous X-ray Source in M82

    Full text link
    The ultraluminous x-ray source (ULX) in the galaxy M82 has been identified as a possible intermediate-mass black hole. We have found that the x-ray flux from M82 is modulated with a peak-to-peak amplitude corresponding to an isotropic luminosity of 2.4x10^40 erg/s in M82 and a period of 62.0 +/- 2.5 days, which we interpret as the orbital period of the ULX binary. This orbital period implies that the mass-donor star must be a giant or supergiant. Large mass-transfer rates, sufficient to fuel the ULX, are expected for a giant-phase mass donor in an x-ray binary. The giant phase has a short lifetime, indicating that we see the ULX in M82 in a brief and unusual period of its evolution.Comment: 3 pages, appeared in Scienc

    Weak lensing calibration of mass bias in the REFLEX+BCS X-ray galaxy cluster catalogue

    Full text link
    The use of large, X-ray selected galaxy cluster catalogues for cosmological analyses requires a thorough understanding of the X-ray mass estimates. Weak gravitational lensing is an ideal method to shed light on such issues, due to its insensitivity to the cluster dynamical state. We perform a weak lensing calibration of 166 galaxy clusters from the REFLEX and BCS cluster catalogue and compare our results to the X-ray masses based on scaled luminosities from that catalogue. To interpret the weak lensing signal in terms of cluster masses, we compare the lensing signal to simple theoretical Navarro-Frenk-White models and to simulated cluster lensing profiles, including complications such as cluster substructure, projected large-scale structure, and Eddington bias. We find evidence of underestimation in the X-ray masses, as expected, with MX/MWL=0.75±0.07\langle M_{\mathrm{X}}/M_{\mathrm{WL}}\rangle = 0.75 \pm 0.07 stat. ±0.05\pm 0.05 sys. for our best-fit model. The biases in cosmological parameters in a typical cluster abundance measurement that ignores this mass bias will typically exceed the statistical errors.Comment: 13 pages, 5 figures. Revised to address referee comment

    Solicitation of Public and Private Litigation Under the First Amendment

    Get PDF
    After presenting the solicitation cases, the Article will analyze the nearest precedents bearing on each

    Comparison of Observed Galaxy Properties with Semianalytic Model Predictions using Machine Learning

    Full text link
    With current and upcoming experiments such as WFIRST, Euclid and LSST, we can observe up to billions of galaxies. While such surveys cannot obtain spectra for all observed galaxies, they produce galaxy magnitudes in color filters. This data set behaves like a high-dimensional nonlinear surface, an excellent target for machine learning. In this work, we use a lightcone of semianalytic galaxies tuned to match CANDELS observations from Lu et al. (2014) to train a set of neural networks on a set of galaxy physical properties. We add realistic photometric noise and use trained neural networks to predict stellar masses and average star formation rates on real CANDELS galaxies, comparing our predictions to SED fitting results. On semianalytic galaxies, we are nearly competitive with template-fitting methods, with biases of 0.010.01 dex for stellar mass, 0.090.09 dex for star formation rate, and 0.040.04 dex for metallicity. For the observed CANDELS data, our results are consistent with template fits on the same data at 0.150.15 dex bias in MstarM_{\rm star} and 0.610.61 dex bias in star formation rate. Some of the bias is driven by SED-fitting limitations, rather than limitations on the training set, and some is intrinsic to the neural network method. Further errors are likely caused by differences in noise properties between the semianalytic catalogs and data. Our results show that galaxy physical properties can in principle be measured with neural networks at a competitive degree of accuracy and precision to template-fitting methods.Comment: 19 pages, 10 figures, 6 tables. Accepted for publication in Ap

    Torts—Constructive Release of Co-Tortfeasors Fails

    Get PDF
    Derby v. Prewitt, 12 N.Y.2d 100, 187 N.E.2d 556, 236 N.Y.S.2d 953 (1962) (three judges dissenting)

    Torts—Privity of Contract No Longer Needed in Certain Warranty Actions

    Get PDF
    Battalla v. State, 10 N.Y.2d 237, 219 N.Y.S.2d 34 (1961)

    Concurrent Jurisdiction in Maritime Death—Faith in a Sea Fable?

    Get PDF
    Ledet v. United Aircraft Corp., 10 N.Y.2d 258, 219 N.Y.S.2d 245 (1961)
    corecore