14125535
Dynamical Treatment of Virialization Heating in Galaxy Formation
In a hierarchical picture of galaxy formation virialization continually transforms gravitational potential energy into kinetic energies of the baryonic and dark matter. For the gaseous component the kinetic, turbulent energy is transformed eventually into internal thermal energy through shocks and viscous dissipation. Traditionally this virialization and shock heating has been assumed to occur instantaneously, allowing an estimate of the gas temperature to be derived from the virial temperature defined from the embedding dark matter halo velocity dispersion. As the mass grows the virial temperature of a halo grows. Mass accretion hence can be translated into a heating term. We derive this heating rate from the extended Press Schechter formalism and demonstrate its usefulness in semianalytical models of galaxy formation. Our method explicitly conserves energy, unlike the previous impulsive heating assumptions. Our formalism can trivially be applied in all current semianalytical models as the heating term can be computed directly from the underlying merger trees. Our analytic results for the first cooling halos and the transition from cold to hot accretion are in agreement with numerical simulations.
118693667
Gamma ray observations of the orion molecular clouds with the fermi large area telescope
We report on the gamma-ray observations of giant molecular clouds Orion A and B with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The gamma-ray emission in the energy band between ∼100 MeV and ∼100 GeV is predicted to trace the gas mass distribution in the clouds through nuclear interactions between the Galactic cosmic rays (CRs) and interstellar gas. The gamma-ray production cross-section for the nuclear interaction is known to ∼10% precision which makes the LAT a powerful tool to measure the gas mass column density distribution of molecular clouds for a known CR intensity. We present here such distributions for Orion A and B, and correlate them with those of the velocity-integrated CO intensity (WCO) at a 1◦ × 1◦ pixel level. The correlation is found to be linear over a WCO range of ∼10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The WCO-to-mass conversion factor, XCO, is found to be ∼2.3 × 1020 cm−2 (K km s−1)−1 for the high-longitude part of Orion A (l > 212◦), ∼1.7 times higher than ∼1.3 × 1020 found for the rest of Orion A and B. We interpret the apparent high XCO in the high-longitude region of Orion A in the light of recent works proposing a nonlinear relation between H2 and CO densities in the diffuse molecular gas. WCO decreases faster than the H2 column density in the region making the gas "darker" to WCO.
119304648
RADIO AND γ-RAY CONSTRAINTS ON THE EMISSION GEOMETRY AND BIRTHPLACE OF PSR J2043+2740
We report on the first year of Fermi gamma-ray observations of pulsed high-energy emission from the old PSR J2043+2740. The study of the gamma-ray efficiency of such old pulsars gives us an insight into the evolution of pulsars' ability to emit in gammma rays as they age. The gamma-ray lightcurve of this pulsar above 0.1 GeV is clearly defined by two sharp peaks, 0.353+/-0.035 periods apart. We have combined the gamma-ray profile characteristics of PSR J2043+2740 with the geometrical properties of the pulsar's radio emission, derived from radio polarization data, and constrained the pulsar-beam geometry in the framework of a Two Pole Caustic and an Outer Gap model. The ranges of magnetic inclination and viewing angle were determined to be {alpha,zeta}~{52-57,61-68} for the Two Pole Caustic model, and {alpha,zeta}~{62-73,74-81} and {alpha,zeta}~{72-83,60-75} for the Outer Gap model. Based on this geometry, we assess possible birth locations for this pulsar and derive a likely proper motion, sufficiently high to be measurable with VLBI. At a characteristic age of 1.2 Myr, PSR J2043+2740 is the third oldest of all discovered, non-recycled, gamma-ray pulsars: it is twice as old as the next oldest, PSR J0357+32, and younger only than the recently discovered PSR J1836+5925 and PSR J2055+25, both of which are at least 5 and 10 times less energetic, respectively.
55341209
OPERATION OF PEP IN A LOW EMITTANCE MODE
I’KI’ has I)crn IISC~ as a. source of synchrol.ron ra.diat.ion with at, 11nd~lat0r beam line operating parasitically tlurirtg particle pllysics runs at 14.5 GeV bca.m energy. ‘I’hc l)ossibi!ltlF. of using PEP in a dcdicntcrl mode for synchr0(1.011 racllat,lon have tenon considered. Since a lower bran1 r~~crgy is preferred in this cast, PEP has hcen succrssfully op~~ratctt at. 8 GeV where I.hr uricc,nplctl l~ra111 ctnittance is 27 null ratl. It is of int.erest to r~lucc this clnit.tance fnrther wit.h a tliffrrent opt,ics ha.ving strongrr horizont~al focnssing. This has I)een (lone by increasing tile horizontal heMron phase aclvauw per cell from 56” 1.0 I 00” resuIt.ing in an cmit,t,ance of about 9 1llJ1 rnd. To keep t,he strc~ngth of the sext 11p0lcs and their crV a l>eam was successfully injected and n.ccn~iiula.led. ‘I’he hol.izontal arid ~.~rtit.nl eniit tanccs were n~easllrc~tl Itsing the photon J)talll of the 58 111 long un(lulator hnnl lint- iI found to be 12.1 ant1 1 2 nnl ~,ntl. This is close to t,hr exp~ct,r~l value of 9.9 11111 ract for the SI~III of the two. The I)ealll lift, t.imr was over 30 110111.S at low cllrrcnts. Diffrrcn! mcltiods of rctliicing this emit.tancr cvcn further are invcst.iRat,e(l. Jncrcasillg tllc horizonl.al tlalnping pal.tition front .J, = rto .r, = 2 looks nlost prornisil.~g. This does uot rquirc new hardware bnl can IJ~ achieved WIllI a. s111nt1 increase of the RF-frequency of about ‘I kHz. Such au operation mode has been co~nputed ant1 tracked. The dyna.mic accrpt.ancr is very large and the expectrtl nnc~onplcd eniitt.ance is ,I.3 *11n rad at 8 (;eV.
118924226
Analysis Methods for Milky Way Dark Matter Satellite Detection
The Gamma Ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Dark Matter and New Physics Working group has been developing approaches for the indirect detection of in situ annihilation of dark matter. Our work has assumed that a significant component of dark matter is a new type of Weakly Interacting Massive Particle (WIMP) in the 100GeV mass range. The annihilation of two WIMPs results in the production of a large number of high energy gamma rays (>1GeV) that can be well measured by the GLAST LAT. The cold dark matter model implies a significant number of as yet unobserved dark matter satellites in our galaxy. The spectra of these galactic satellites are considerably harder than most, if not all, astrophysical sources, have an endpoint at the mass of the WIMP, and are not power laws. We describe a preliminary feasibility study for the indirect detection of dark matter satellites in the Milky Way using the GLAST LAT.
27791621
The radio/gamma-ray connection in active galactic nuclei in the era of the Fermi large area telescope
We present a detailed statistical analysis of the correlation between radio and gamma-ray emission of the active galactic nuclei (AGNs) detected by Fermi during its first year of operation, with the largest data sets ever used for this purpose. We use both archival interferometric 8.4 GHz data (from the Very Large Array and ATCA, for the full sample of 599 sources) and concurrent single-dish 15 GHz measurements from the Owens Valley Radio Observatory (OVRO, for a sub sample of 199 objects). Our unprecedentedly large sample permits us to assess with high accuracy the statistical significance of the correlation, using a surrogate data method designed to simultaneously account for common-distance bias and the effect of a limited dynamical range in the observed quantities. We find that the statistical significance of a positive correlation between the centimeter radio and the broadband (E > 100 MeV) gamma-ray energy flux is very high for the whole AGN sample, with a probability of < 10(-7) for the correlation appearing by chance. Using the OVRO data, we find that concurrent data improve the significance of the correlation from 1.6 x 10(-6) to 9.0 x 10(-8). Our large sample size allows us to study the dependence of correlation strength and significance on specific source types and gamma-ray energy band. We find that the correlation is very significant (chance probability < 10(-7)) for both flat spectrum radio quasars and BL Lac objects separately; a dependence of the correlation strength on the considered gamma-ray energy band is also present, but additional data will be necessary to constrain its significance.
119717624
Asymmetric nuclear matter at finite temperature and density
Asymmetric nuclear matter is studied by using an effective nuclear model in a mean-field approximation. The density, temperature, and asymmetric parameter dependence of the effective baryon mass is discussed. The liquid-gas phase transition of a system with two independent conserved charges (baryon number and isospin) is studied using the stability conditions on the free energy and Gibbs conditions for phase equilibrium. The critical temperature is calculated with and without $\ensuremath{\rho}$ meson contribution, respectively.
119728121
Coulomb instability of hot nuclei in a chiral symmetry model
A chiral symmetry model for nuclear matter is extended to finite temperature and then used to study the Coulomb instability of hot nuclei. The role of the rho meson degree of freedom is discussed. The calculated limiting temperature is compared with the results obtained from other theories and experiments. [S0556-2813(99)05006-2].
121138073
BESII detector simulation
A Monte Carlo program based on GEANT3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.
125811501
Search for anti-B0 ---> Lambda+(c) Lambda-(c) decay at Belle
128213646
A ug 2 01 0 Observation of an enhancement in
K.-F. Chen, W.-S. Hou, I. Adachi, H. Aihara, T. Aushev, 13 A. M. Bakich, V. Balagura, A. Bay, K. Belous, V. Bhardwaj, M. Bischofberger, A. Bondar, 32 A. Bozek, M. Bračko, J. Brodzicka, T. E. Browder, M.-C. Chang, P. Chang, Y. Chao, A. Chen, P. Chen, B. G. Cheon, C.-C. Chiang, R. Chistov, I.-S. Cho, Y. Choi, J. Dalseno, 41 A. Drutskoy, S. Eidelman, 32 D. Epifanov, 32 N. Gabyshev, 32 P. Goldenzweig, H. Ha, B.-Y. Han, K. Hayasaka, H. Hayashii, M. Hazumi, Y. Hoshi, Y. B. Hsiung, H. J. Hyun, T. Iijima, K. Inami, R. Itoh, M. Iwabuchi, Y. Iwasaki, T. Julius, D. H. Kah, J. H. Kang, N. Katayama, C. Kiesling, H. O. Kim, Y. I. Kim, Y. J. Kim, K. Kinoshita, B. R. Ko, S. Korpar, 14 P. Križan, 14 P. Krokovny, Y.-J. Kwon, S.-H. Kyeong, J. S. Lange, S.-H. Lee, J. Li, C. Liu, Y. Liu, D. Liventsev, R. Louvot, J. MacNaughton, A. Matyja, S. McOnie, K. Miyabayashi, H. Miyata, Y. Miyazaki, R. Mizuk, Y. Nagasaka, E. Nakano, M. Nakao, S. Nishida, K. Nishimura, O. Nitoh, T. Nozaki, S. Ogawa, T. Ohshima, S. Okuno, G. Pakhlova, H. Park, H. K. Park, R. Pestotnik, M. Petrič, L. E. Piilonen, S. Ryu, H. Sahoo, K. Sakai, Y. Sakai, O. Schneider, C. Schwanda, A. J. Schwartz, R. Seidl, K. Senyo, M. Shapkin, C. P. Shen, J.-G. Shiu, B. Shwartz, 32 P. Smerkol, A. Sokolov, E. Solovieva, S. Stanič, M. Starič, K. Sumisawa, T. Sumiyoshi, S. Suzuki, Y. Teramoto, K. Trabelsi, S. Uehara, T. Uglov, Y. Unno, S. Uno, Y. Ushiroda, G. Varner, K. E. Varvell, K. Vervink, C. H. Wang, M.-Z. Wang, P. Wang, Y. Watanabe, R. Wedd, J. Wicht, E. Won, B. D. Yabsley, Y. Yamashita, C. Z. Yuan, Z. P. Zhang, V. Zhulanov, 32 A. Zupanc, and O. Zyukova 32