On the evolutionary status of early-type galaxies in clusters at z ≈ 0.2 - I. The fundamental plane
Monthly Notices of the Royal Astronomical Society 358:1 (2005) 233-255
Abstract:
We investigate a spectroscopic sample of 48 early-type galaxies in the rich cluster Abell 2390 at z = 0.23 and 48 early-type galaxies from a previously published survey of Abell 2218 at z = 0.18. The spectroscopic data of A 2390 are based on multi-object spectroscopy using the multi-object spectrograph for Calar Alto at the 3.5-m telescope on Calar Alto Observatory and are complemented by ground-based imaging using the 5.1-m Hale telescope and Hubble Space Telescope (HST) observations in the F555W and F814W filters. Our investigation spans a broad range in luminosity (-20.5 ≥ Mr ≥ -23.0) and a rather wide field of view of 1.53 h70-1 × 1.53 h70-1 Mpc2. As the A 2218 and A2390 samples are very similar, we can combine them and analyse a total number of 96 early-type (E+S0) galaxies at z ∼ 0.2. Using the ground-based data only, we construct the Faber-Jackson relation (FJR) for all 96 E+S0 galaxies and detect a modest luminosity evolution with respect to the local reference. The average offset from the local FJR in the Gunn r band is Δ ̄Mr = 0.32 ± 0.22 mag. Similar results are derived for each cluster separately. Less massive galaxies show a trend for a larger evolution than more massive galaxies. HST/WFPC2 surface brightness profile fits were used to derive the structural parameters for a subsample of 34 E+S0 galaxies. We explore the evolution of the Fundamental Plane (FP) in Gunn r, its projections on to the Kormendy relation and the M/L ratios as a function of velocity dispersion. The FP for the cluster galaxies is offset from the local Coma cluster FP. At a fixed effective radius and velocity dispersion our galaxies are brighter than their local counterparts. For the total sample of 34 E+S0 cluster galaxies which enter the FP we deduce only a mild evolution with a zero-point offset of 0.10 ± 0.06, corresponding to a brightening of 0.31 ± 0.18 mag. Elliptical and lenticular galaxies are uniformly distributed along the FP with a similar scatter of 0.1 dex. Within our sample we find little evidence for differences between the populations of elliptical and S0 galaxies. There is a slight trend that lenticulars induce on average a larger evolution of 0.44 ± 0.18 mag than ellipticals with 0.02 ± 0.21 mag. The M/L ratios of our distant cluster galaxies at z = 0.2 are offset by Δlog (M/L r) = -0.12 ± 0.06 dex compared with those of Coma. Our results can be reconciled with a passive evolution of the stellar populations and a high formation redshift for the bulk of the stars in early-type galaxies. However, our findings are also consistent with the hierarchical formation picture for rich clusters, if ellipticals in clusters had their last major merger at high redshift. © 2005 RAS.Measurement of the lifetime difference between Bs mass eigenstates.
Phys Rev Lett 94:10 (2005) 101803
Abstract:
We present measurements of the lifetimes and polarization amplitudes for B(0)(s)-->J/psiphi and B(0)(d)-->J/psiK(*0) decays. Lifetimes of the heavy and light mass eigenstates in the B(0)(s) system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203+/-15 B(0)(s) decays we obtain tau(L) = (1.05(+0.16)(-0.13) +/- 0.02) ps and tau(H) = (2.07(+0.58)(-0.46) +/- 0.03) ps. Expressed in terms of the difference DeltaGamma(s) and average Gamma(s), of the decay rates of the two eigenstates, the results are DeltaGamma(s)/Gamma(s) = (65(+25)(-33) +/- 1)% and DeltaGamma(s) = (0.47(+0.19)(-0.24) +/- 0.01) ps(-1).First measurements of inclusive W and Z cross sections from run II of the fermilab tevatron collider.
Phys Rev Lett 94:9 (2005) 091803
Abstract:
We report the first measurements of inclusive W and Z cross sections times leptonic branching ratios for pp collisions at square root[s]=1.96 TeV, based on their decays to electrons and muons. The data correspond to an integrated luminosity of 72 pb(-1) recorded with the CDF detector at the Fermilab Tevatron. We test e-mu universality in W decays, and we measure the ratio of leptonic W and Z rates from which the leptonic branching fraction B(W-->lnu) can be extracted as well as an indirect value for the total width of the W and the Cabibbo-Kobayashi-Maskawa matrix element, |V(cs)|.Erratum: Measurement of the W boson polarization in top decay at CDF at √s p = 1:8 TeV (Physical Review D (2005) 71 (031101))
Physical Review D - Particles, Fields, Gravitation and Cosmology 71:5 (2005) 1-2
Measurement of the forward-backward charge asymmetry from W→ev production in pp̄ collisions at √s=1.96 TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 71:5 (2005) 1-9