118664311
Detection of outflowing and extraplanar gas in disks in an assembling galaxy cluster at z = 0.37
We detect ionized gas characteristics indicative of winds in three disk-dominated galaxies that are members of a super-group at z = 0.37 that will merge to form a Coma-mass cluster. All three galaxies are IR luminous (L IR > 4 × 1010 L ☉, SFR > 8 M ☉ yr–1) and lie outside the X-ray cores of the galaxy groups. We find that the most IR-luminous galaxy has strong blueshifted and redshifted emission lines with velocities of ~ ± 200 km s–1 and a third, blueshifted (~900 km s–1) component. This galaxy's line widths (Hβ, [O III]λ5007, [N II], Hα) correspond to velocities of 100-1000 km s–1. We detect extraplanar gas in two of the three galaxies with SFR >8 M ☉ yr–1 whose orientations are approximately edge-on and which have integral field unit (IFU) spaxels off the stellar disk. IFU maps reveal that the extraplanar gas extends to rh ~ 10 kpc; [N II] and Hα line widths correspond to velocities of ~200-400 km s–1 in the disk and decrease to ~50-150 km s–1 above the disk. Multi-wavelength observations indicate that the emission is dominated by star formation. Including the most IR-luminous galaxy we find that 18% of supergroup members with SFR >8 M ☉ yr–1 show ionized gas characteristics indicative of outflows. This is a lower limit as showing that gas is outflowing in the remaining, moderately inclined, galaxies requires a non-trivial decoupling of contributions to the emission lines from rotational and turbulent motion. Ionized gas mass loss in these winds is ~0.1 M ☉ yr–1 for each galaxy, although the winds are likely to entrain significantly larger amounts of mass in neutral and molecular gases.
15714969
H I Observations of Five Groups of Galaxies
We present the results of H I observations of five groups of galaxies spanning a range of velocity dispersion and spiral fraction (brightest optical group member in parenthesis): NGC 7582 (NGC 7552), USGC U207 (NGC 2759), USGC U070 (NGC 664), USGC U412 (NGC 3822), USGC U451 (NGC 4065). Neutral intragroup gas is detected in three of the five groups. We present the discovery of a previously uncataloged galaxy in the USGC U070 group at α(2000) = 01h45m27s, δ(2000) = +0436'19'', which we are designating FSW J014526.92+043619.1. We compile an H I mass function for the group environment and find that the faint-end slope is consistent with being flat.
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.
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.
119216322
Quantifying the importance of ram-pressure stripping in a galaxy group at 100 Mpc
We examine two members of the NGC 4065 group of galaxies: a bent-double (aka wide angle tail) radio source and an H I-deficient spiral galaxy. Models of the X-ray-emitting intragroup gas and the bent-double radio source, NGC 4061, are used to probe the density of intergalactic gas in this group. H I observations reveal an asymmetric, truncated distribution of H I in spiral galaxy, UGC 07049, and the accompanying radio continuum emission reveals strong star formation. We examine the effectiveness of ram-pressure stripping as a gas-removal mechanism and find that it alone cannot account for the H i deficiency that is observed in UGC 07049 unless this galaxy has passed through the core of the group with a velocity of ~800 km s -1 . A combination of tidal and ram-pressure stripping are necessary to produce the H I deficiency and asymmetry in this galaxy.
118605285
Simulations of bent-double radio sources in galaxy groups
Bent-double radio sources have been used as a probe to measure the density of intergalactic gas in galaxy groups. We carry out a series of high-resolution, three-dimensional simulations of active galactic nucleus (AGN) jets moving through an external medium with a constant density in order to develop a general formula for the radius of curvature of the jets, and to determine how accurately the density of the intra-group medium (IGM) can be measured. Our simulations produce curved jets ending in bright radio lobes with an extended trail of low surface brightness radio emission. The radius of curvature of the jets varies with time by only about 25 per cent. The radio trail seen in our simulations is typically not detected in known sources, but may be detectable in lower resolution radio observations. The length of this tail can be used to determine the age of the AGN. We also use our simulation data to derive a formula for the kinetic luminosity of observed jets in terms of the radius of curvature and jet pressure. In characterizing how well observations can measure the IGM density, we find that the limited resolution of typical radio observations leads to a systematic underestimate of the IGM density of about 50 per cent. The unknown angles between the observer and the direction of jet propagation and direction of AGN motion through the IGM lead to an uncertainty of about +/- 50 per cent in estimates of the IGM density. Previous conclusions drawn using these sources, indicating that galaxy groups contain significant reservoirs of baryons in their IGM, are still valid when considering this level of uncertainty. In addition, we model the X-ray emission expected from bent-double radio sources. We find that known sources in reasonably dense environments should be detectable in similar to 100 ks Chandra observations. X-ray observations of these sources would place constraints on the IGM density and AGN velocity that are complementary to radio observations.
123473314
Heavy-Quark Masses from the Fermilab Method in Three-Flavor Lattice QCD
We report on heavy quark mass calculations using Fermilab heavy quarks. Lattice calculations of heavy-strange meson masses are combined with one-loop (automated) lattice perturbation theory to arrive at the quark mass. Mesons are constructed from Fermilab heavy quarks and staggered light quarks. We use the MILC ensembles at three lattice spacings and sea quark mass ratios of m{sub u,d}/m{sub s} = 0.1 to 0.4. Preliminary results for the bottom quark are given in the potential subtracted scheme.
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
125344677
$\bar{\Lambda}$, $\lambda_1$, and $m_b$ in three-flavor (lattice) QCD.
118356540
$B^0_s$ and $B^0$ Mixing in the Standard Model and Beyond: A Progress Report
We give a progress report on the calculation of B meson mixing matrix elements, focusing on contributions that could arise beyond the Standard Model. The calculation uses asqtad (light quark) and Fermilab (heavy quark) valence actions and MILC ensembles with 2+1 flavors of asqtad sea quarks. We report preliminary B{sub s}{sup 0} fit results, at a lattice spacing of 0.12 fm, for the SUSY basis of effective four-quark mixing operators and include an estimate for the final error budget.