103 research outputs found

    Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate of Short GRBs in Field and Cluster Early-Type Galaxies

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    We determine the relative rates of short GRBs in cluster and field early-type galaxies as a function of the age probability distribution of their progenitors, P(\tau) \propto \tau^n. This analysis takes advantage of the difference in the growth of stellar mass in clusters and in the field, which arises from the combined effects of the galaxy stellar mass function, the early-type fraction, and the dependence of star formation history on mass and environment. This approach complements the use of the early- to late-type host galaxy ratio, with the added benefit that the star formation histories of early-type galaxies are simpler than those of late-type galaxies, and any systematic differences between progenitors in early- and late-type galaxies are removed. We find that the ratio varies from R(cluster)/R(field) ~ 0.5 for n = -2 to ~ 3 for n = 2. Current observations indicate a ratio of about 2, corresponding to n ~ 0 - 1. This is similar to the value inferred from the ratio of short GRBs in early- and late-type hosts, but it differs from the value of n ~ -1 for NS binaries in the Milky Way. We stress that this general approach can be easily modified with improved knowledge of the effects of environment and mass on the build-up of stellar mass, as well as the effect of globular clusters on the short GRB rate. It can also be used to assess the age distribution of Type Ia supernova progenitors.Comment: ApJ accepted versio

    Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC

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    A determination of electroweak parameters from Z0→μ+μ- (γ)

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    High mass photon pairs in ℓ+ℓ−γγ events at LEP

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    Search for excited taus from Z0 decays

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    Test of QED in e+e−→γγ at LEP

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    Measurement of inclusive η production in hadronic decays of the Z0

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    Study of the KS0KS0 final state in two-photon collisions

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    A measurement of τ polarization in Z0 decays

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    Measurement of the inclusive b→τνX branching ratio

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