Galaxy Zoo: A sample of blue early-type galaxies at low redshift
ArXiv 0903.3415 (2009)
Abstract:
We report the discovery of a population of nearby, blue early-type galaxies with high star formation rates (0.5 < SFR < 50 Msun/yr). They are identified by their visual morphology as provided by Galaxy Zoo for SDSS DR6 and their u-r colour. We select a volume-limited sample in the redshift range 0.02 < z < 0.05, corresponding to luminosities of approximately L* and above, and with u-r colours significantly bluer than the red sequence. We confirm the early-type morphology of the objects in this sample and investigate their environmental dependence and star formation properties. Blue early-type galaxies tend to live in lower-density environments than `normal' red sequence early-types and make up 5.7 +/-0.4% of the low-redshift early-type galaxy population. We find that such blue early-type galaxies are virtually absent at high velocity dispersions above 200 km/s. Our analysis uses emission line diganostic diagrams and we find that ~25% of them are actively starforming, while another ~25% host both star formation and an AGN. Another ~12% are AGN. The remaining 38% show no strong emission lines. When present and uncontaminated by an AGN contribution, the star formation is generally intense. We consider star formation rates derived from Halpha, u-band and infrared luminosities, and radial colour profiles, and conclude that the star formation is spatially extended. Of those objects that are not currently undergoing star formation must have ceased doing so recently in order to account for their blue optical colours. The gas phase metallicity of the actively starforming blue early-types galaxies is supersolar in all cases. We discuss the place of these objects in the context of galaxy formation. A catalogue of all 204 blue early-type galaxies in our sample, including star formation rates and emission line classification, is provided.Measurement of resonance parameters of orbitally excited narrow B0 mesons.
Phys Rev Lett 102:10 (2009) 102003
Abstract:
We report a measurement of resonance parameters of the orbitally excited (L=1) narrow B0 mesons in decays to B;{(*)+}pi;{-} using 1.7 fb;{-1} of data collected by the CDF II detector at the Fermilab Tevatron. The mass and width of the B_{2};{*0} state are measured to be m(B_{2};{*0})=5740.2_{-1.8};{+1.7}(stat)-0.8+0.9(syst) MeV/c;{2} and Gamma(B_{2};{*0})=22.7_{-3.2};{+3.8}(stat)-10.2+3.2(syst) MeV/c;{2}. The mass difference between the B_{2};{*0} and B10 states is measured to be 14.9_{-2.5};{+2.2}(stat)-1.4+1.2(syst) MeV/c;{2}, resulting in a B10 mass of 5725.3_{-2.2};{+1.6}(stat)-1.5+1.4(syst) MeV/c;{2}. This is currently the most precise measurement of the masses of these states and the first measurement of the B_{2};{*0} width.SN 2008S: an electron capture SN from a super-AGB progenitor?
(2009)
Search for high-mass resonances decaying to dimuons at CDF.
Phys Rev Lett 102:9 (2009) 091805
Abstract:
We present a search for high-mass neutral resonances using dimuon data corresponding to an integrated luminosity of 2.3 fb(-1) collected in pp[over ] collisions at sqrt[s]=1.96 TeV by the CDF II detector at the Fermilab Tevatron. No significant excess above the standard model expectation is observed in the dimuon invariant-mass spectrum. We set 95% confidence level upper limits on sigmaBR(pp-->X-->micromicro), where X is a boson with spin-0, 1, or 2. Using these cross section limits, we determine lower mass limits on sneutrinos in R-parity-violating supersymmetric models, Z' bosons, and Kaluza-Klein gravitons in the Randall-Sundrum model.Improved measurement of absolute branching fraction of Ds+→τ+ν τ
Physical Review D - Particles, Fields, Gravitation and Cosmology 79:5 (2009)