18150020
BENT-DOUBLE RADIO SOURCES AS PROBES OF INTERGALACTIC GAS
As the most common environment in the universe, groups of galaxies are likely to contain a significant fraction of the missing baryons in the form of intergalactic gas. The density of this gas is an important factor in whether ram pressure stripping and strangulation affect the evolution of galaxies in these systems. We present a method for measuring the density of intergalactic gas using bent-double radio sources that is independent of temperature, making it complementary to current absorption-line measurements. We use this method to probe intergalactic gas in two different environments, inside a small group of galaxies as well as outside of a larger group at a 2 Mpc radius, and measure total gas densities of -->4 ± 1+6−2 × 10−3 cm−3 and -->9 ± 3+10−5 × 10−4 cm−3 (random and systematic errors), respectively. We use X-ray data to place an upper limit of -->2 × 106 K on the temperature of the intragroup gas in the small group.
119286034
INTERGALACTIC GAS IN GROUPS OF GALAXIES: IMPLICATIONS FOR DWARF SPHEROIDAL FORMATION AND THE MISSING BARYONS PROBLEM
Radio galaxies with bent jets are predominantly located in groups and clusters of galaxies. We use bent-double radio sources, under the assumption that their jets are bent by ram pressure, to probe intragroup medium (IGM) gas densities in galaxy groups. This method provides a direct measurement of the intergalactic gas density and allows us to probe intergalactic gas at large radii and in systems whose IGM is too cool to be detected by the current generation of X-ray telescopes. We find gas with densities of 10{sup -3} to 10{sup -4} cm{sup -3} at group radii from 15 to 700 kpc. A rough estimate of the total baryonic mass in intergalactic gas is consistent with the missing baryons being located in the IGM of galaxy groups. The neutral gas will be easily stripped from dwarf galaxies with total masses of 10{sup 6}-10{sup 7} M{sub sun} in the groups studied here. Indications are that intragroup gas densities in less-massive systems like the Local Group should be high enough to strip gas from dwarfs like Leo T and, in combination with tides, produce dwarf spheroidals.
118672859
EVIDENCE FOR A STRONG END-ON BAR IN THE RINGED σ-DROP GALAXY NGC 6503
We use WIYN High-resolution Infrared Camera H-band (1.6 μm) imaging, archival Spitzer, Hubble Space Telescope, and Galaxy Evolution Explorer data simulations, and data from the literature to argue for the presence of a strong end-on bar in nearby spiral galaxy NGC 6503. The evidence consists of both photometric and kinematic signatures as well as resonant structures present in the galaxy which are most often associated with bars. These include a central peak followed by a plateau in the surface brightness profile, an extreme decrement in the central stellar velocity dispersion (a σ-drop), and the presence of an inner ring as well as a circumnuclear disk with spiral structure. In this framework, the previously identified nuclear star-forming ring is instead a young inner ring spanned in diameter by the strong end-on bar.
119241694
Matrix Elements for D- and B-Mixing from 2+1 Flavor Lattice QCD
C.C. Chang∗ a f , C. Bernard b, C.M. Bouchard c, A.X. El-Khadra a f , E.D. Freeland d, E. Gamiz e, A.S. Kronfeld f , J. Laiho g, R.S. van de Water f aPhysics Department, University of Illinois, Urbana, IL 61801, USA bDepartment of Physics, Washington University, St. Louis, MO 63130, USA cDepartment of Physics, The Ohio State University, Columbus, OH 43210, USA dLiberal Arts Department, The School of the Art Institute of Chicago, Chicago, IL 60603, USA eCAFPE and Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, E-18002 Granada, Spain fTheoretical Physics Department, Fermi National Accelerator Laboratory†, Batavia, IL 60510, USA gSUPA, Department of Physics and Astronomy, University of Glasgow, Glasgow, G12-8QQ, United Kingdom