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New measurement of the masses and widths of the ∑c *++ and ∑c*0 charmed baryons

Physical Review D Particles Fields Gravitation and Cosmology 71:5 (2005) 1-4

Authors:

SB Athar, P Avery, L Breva-Newell, R Patel, V Potlia, H Stoeck, J Yelton, P Rubin, C Cawlfield, BI Eisenstein, GD Gollin, I Karliner, D Kim, N Lowrey, P Naik, C Sedlack, M Selen, JJ Thaler, J Williams, J Wiss, KW Edwards, D Besson, TK Pedlar, KY Gao, DT Gong, Y Kubota, BW Lang, SZ Li, R Poling, AW Scott, A Smith, CJ Stepaniak, S Dobbs, Z Metreveli, KK Seth, A Tomaradze, P Zweber, J Ernst, AH Mahmood, K Arms, KK Gan, H Severini, DM Asner, SA Dytman, W Love, S Mehrabyan, JA Mueller, V Savinov, Z Li, A Lopez, H Mendez, J Ramirez, GS Huang, DH Miller, V Pavlunin, B Sanghi, EI Shibata, IPJ Shipsey, GS Adams, M Chasse, M Cravey, JP Cummings, I Danko, J Napolitano, D Cronin-Hennessy, CS Park, W Park, JB Thayer, EH Thorndike, TE Coan, YS Gao, F Liu, M Artuso, C Boulahouache, S Blusk, J Butt, E Dambasuren, O Dorjkhaidav, N Menaa, R Mountain, H Muramatsu, R Nandakumar, R Redjimi, R Sia, T Skwarnicki, S Stone, JC Wang, K Zhang, SE Csorna, G Bonvicini, D Cinabro, M Dubrovin, A Bornheim, SP Pappas, AJ Weinstein, RA Briere, GP Chen, T Ferguson, G Tatishvili, H Vogel

Abstract:

Using data recorded by the CLEO III detector at the Cornell electron storage ring (CESR), we have made measurements of some properties of the ∑c*++ and ∑c*0 charmed baryons. In particular: Γ(∑c*++) = 14.4-1.5+1.6 ± 1.4 MeV, M(∑c *++) - M(Λc+) = 231.5 ± 0.4 ± 0.3 MeV, Γ(∑c*0) = 16.6 -1.7+1.9 ± 1.4 MeV, M(∑c *0) -M(Λc+) = 231.4 ± 0.5 ± 0.3 MeV. © 2005 The American Physical Society.

RX J0152.7-1357: Stellar populations in an x-ray luminous galaxy cluster at z = 0.83

Astronomical Journal 129:3 (2005) 1249-1286

Authors:

I Jørgensen, M Bergmann, R Davies, J Barr, M Takamiya, D Crampton

Abstract:

We present a study of the stellar populations of galaxies in the cluster RX J0 152.7-1357 at a redshift of 0.83. The study is based on new high signal-to-noise ratio spectroscopy of 29 cluster members covering the wavelength range 5000-10000 Å, as well as r′i′z′ photometry of the cluster. We use scaling relations between the central velocity dispersions of the galaxies and their luminosities, Balmer line strengths, and various metal line strengths to parameterize the differences between the members of RX J0152.7-1357 and our low-redshift comparison sample. The luminosities of the RX J0152.7-1357 galaxies and the strengths of the higher order Balmer lines H γ and Rδ (for non-emission-line galaxies) appear to be in agreement with pure passive evolution of the stellar populations with a formation redshift Z form ≈ 4. However, the strengths of the D4000 indices and the metal indices do not support this interpretation. Compared with our low-redshift comparison sample, the metal indices (C4668, Fe4383, CN3883, G4300, and CN 2) show that at least half of the non-emission-line galaxies in RX J0152.7-1357 have an Q-element abundance ratio [a/Fe] of 0.2 dex higher, and about half of the galaxies have significantly lower metal content. X-ray data have previously shown that RX J0152.7-1357 is in the process of merging from two sub-clumps. We find that differences in stellar populations of the galaxies are associated with the location of the galaxies relative to the X-ray emission. The galaxies with weak C4668 and G4300, as well as galaxies for which weak [0 II] emission indicates a very recent star formation episode involving about 1% of the mass, are located in areas of low X-ray luminosity, on the outskirts of the two subclumps. It is possible that these galaxies are experiencing the effect of the cluster merger as (short) episodes of star formation, while the galaxies in the cores of the subclumps are unaffected by the merger. The spectroscopy of the RX JO 152.7-1357 galaxies shows for the first time galaxies in a rich cluster at intermediate redshift that cannot evolve passively into the present-day galaxy population in rich clusters. Additional physical processes may be at work, and we speculate that merging with infalling (disk) galaxies in which stars have formed over an extended period might produce the required reduction in [a/Fe]. However, the merging could not be accompanied by star formation involving a substantial mass fraction. We note that our conclusions, in part, rely on stellar population models for which the predictions of the indices in the rest-frame blue have not yet been tested extensively. © 2005. The American Astronomical Society. All rights reserved.

The discovery of a type II quasar at z= 1.65 with integral-field spectroscopy

\mnras 358 (2005) L11-L15-L11-L15

Authors:

MJ Jarvis, C van Breukelen, RJ Wilman

An expanding radio nebula produced by a giant flare from the magnetar SGR 1806-20

(2005)

Authors:

BM Gaensler, C Kouveliotou, JD Gelfand, GB Taylor, D Eichler, RAMJ Wijers, J Granot, E Ramirez-Ruiz, YE Lyubarsky, RW Hunstead, D Campbell-Wilson, AJ van der Host, MA McLaughlin, RP Fender, MA Garrett, KJ Newton-McGee, DM Palmer, N Gehrels, PM Woods

Molecular abundance ratios as a tracer of accelerated collapse in regions of high-mass star formation

Astrophysical Journal 620:2 I (2005) 795-799

Authors:

CJ Lintott, S Viti, JMC Rawlings, DA Williams, TW Hartquist, P Caselli, I Zinchenko, P Myers

Abstract:

Recent observations suggest that the behavior of tracer species such as N2H+ and CS is significantly different in regions of high- and low-mass star formation. In the latter, N2H+ is a good tracer of mass, while CS is not. Observations show the reverse to be true in high-mass star formation regions. We use a computational chemical model to show that the abundances of these and other species may be significantly altered by a period of accelerated collapse in high-mass star-forming regions. We suggest that these results provide a potential explanation of the observations, and make predictions for the behavior of other species. © 2005. The American Astronomical Society. All rights reserved.