The Theory of Parity Violation in Few-Nucleon Systems

We review recent progress in the theoretical description of hadronic parity violation in few-nucleon systems. After introducing the different methods that have been used to study parity-violating observables we discuss the available calculations for reactions with up to five nucleons. Particular emphasis is put on effective field theory calculations where they exist, but earlier and complementary approaches are also presented. We hope this review will serve as a guide for those who wish to know what calculations are available and what further calculations need to be completed before we can claim to have a comprehensive picture of parity violation in few nucleon systems.Comment: 69 pages, 10 figures, accepted for publication in Prog. Part. Nucl. Phy

Infalling Faint [OII] Emitters in Abell 851. I. Spectroscopic Confirmation of Narrowband-Selected Objects

We report on a spectroscopic confirmation of narrowband-selected [OII] emitters in Abell 851 catalogued by Martin et al. (2000). The optical spectra obtained from the Keck I Low Resolution Imaging Spectrometer (LRIS) and Keck II Deep Imaging Multi-Object Spectrograph (DEIMOS) have confirmed [OII]3727 emission in narrowband-selected cluster [OII] candidates at a 85% success rate for faint (i <~ 25) blue (g-i < 1) galaxies. The rate for the successful detection of [OII] emission is a strong function of galaxy color, generally proving the efficacy of narrowband [OII] search supplemented with broadband colors in selecting faint cluster galaxies with recent star formation. Balmer decrement-derived reddening measurements show a high degree of reddening [E(B-V) >~ 0.5] in a significant fraction of this population. Even after correcting for dust extinction, the [OII]/Ha line flux ratio for the high-E(B-V) galaxies remains generally lower by a factor of ~2 than the mean [OII]/Ha ratios reported by the studies of nearby galaxies. The strength of [OII] equivalent width shows a negative trend with galaxy luminosity while the Ha equivalent width does not appear to depend as strongly on luminosity. This in part is due to the high amount of reddening observed in luminous galaxies. Furthermore, emission line ratio diagnostics show that AGN-like galaxies are abundant in the high luminosity end of the cluster [OII]-emitting sample, with only moderately strong [OII] equivalent widths, consistent with a scenario of galaxy evolution connecting AGNs and suppression of star-forming activity in massive galaxies.Comment: 11 pages (LaTeX emulateapj), 8 figures, to appear in ApJ. A version with high resolution figures available from the lead autho

The Stellar Population of Stripped Cluster Spiral NGC 4522: A Local Analog to K+A Galaxies?

We present observations of the stripped Virgo Cluster spiral NGC 4522, a clear, nearby example of a galaxy currently undergoing ISM-ICM stripping. Utilizing SparsePak integral field spectroscopy on the WIYN 3.5m telescope and GALEX UV photometry, we present an analysis of the outer disk (r > 3 kpc) stellar population of this galaxy, beyond the HI and Halpha truncation radius. We find that the star formation in the gas-stripped outer disk ceased very recently, ~100 Myr ago, in agreement with previous claims that this galaxy is currently being stripped. At the time of this stripping, data and models suggest that the galaxy experienced a modest starburst. The stripping is occurring in a region of the cluster well outside the cluster core, likely because this galaxy is experiencing extreme conditions from a dynamic ICM due to an ongoing sub-cluster merger. The outer disk has a spectrum of a K+A galaxy, traditionally observed in high-redshift cluster galaxies. In the case of NGC 4522, a K+A spectrum is formed by simple stripping of the interstellar gas by the hot intracluster medium. These data show K+A spectra can be created by cluster processes and that these processes likely extend beyond the cluster core.Comment: 5 pages, 3 figures, accepted for publication in ApJ Letter

Wide-field weak lensing by RXJ1347-1145

We present an analysis of weak lensing observations for RXJ1347-1145 over a 43' X 43' field taken in B and R filters on the Blanco 4m telescope at CTIO. RXJ1347-1145 is a massive cluster at redshift z=0.45. Using a population of galaxies with 20<R<26, we detect a weak lensing signal at the p<0.0005 level, finding best-fit parameters of \sigma_v=1400^{+130}_{-140} km s^{-1} for a singular isothermal sphere model and r_{200} = 3.5^{+0.8}_{-0.2} Mpc with c = 15^{+64}_{-10} for a NFW model in an \Omega_m = 0.3, \Omega_\Lambda = 0.7 cosmology. In addition, a mass to light ratio M/L_R =90 \pm 20 M_\odot / L_{R\odot} was determined. These values are consistent with the previous weak lensing study of RXJ1347--1145 by Fischer and Tyson, 1997, giving strong evidence that systemic bias was not introduced by the relatively small field of view in that study. Our best-fit parameter values are also consistent with recent X-ray studies by Allen et al, 2002 and Ettori et al, 2001, but are not consistent with recent optical velocity dispersion measurements by Cohen and Kneib, 2002.Comment: accepted to ApJ, tentative publication 10 May 2005, v624

How young are early-type cluster galaxies ? Quantifying the young stellar component in a rich cluster at z=0.41

We present a new method of quantifying the mass fraction of young stars in galaxies by analyzing near-ultraviolet (NUV)-optical colors. We focus our attention on early-type cluster galaxies, whose star formation history is at present undetermined. Rest-frame NUV (F300W) and optical (F702W) images of cluster Abell 851 (z=0.41) using HST/WFPC2 allow us to determine a NUV-optical color-magnitude relation, whose slope is incompatible with a monolithic scenario for star formation at high redshift. A degeneracy between a young stellar component and its fractional mass contribution to the galaxy is found, and a photometric analysis comparing the data with the predictions for a simple two-stage star formation history is presented. The analysis shows that some of the early-type galaxies may have fractions higher than 10% of the total mass content in stars formed at z~0.5. An increased scatter is found in the color-magnitude relation at the faint end, resulting in a significant fraction of faint blue early-type systems. This would imply that less massive galaxies undergo more recent episodes of star formation, and this can be explained in terms of a positive correlation between star formation efficiency and luminosity.Comment: Accepted for publication in ApJ Letters. Uses emulateapj.sty. 5 pages with 3 embedded EPS figure

CHANDRA reveals galaxy cluster with the most massive nearby cooling core, RXCJ1504.1-0248

A CHANDRA follow-up observation of an X-ray luminous galaxy cluster with a compact appearance, RXCJ1504.1-0248 discovered in our REFLEX Cluster Survey, reveals an object with one of the most prominent cluster cooling cores. With a core radius of ~30 kpc smaller than the cooling radius with ~140 kpc more than 70% of the high X-ray luminosity of Lbol = 4.3 10e45 erg s-1 of this cluster is radiated inside the cooling radius. A simple modeling of the X-ray morphology of the cluster leads to a formal mass deposition rate within the classical cooling flow model of 1500 - 1900 Msun yr-1 (for h=0.7), and 2300 - 3000 Msun yr-1 (for h=0.5). The center of the cluster is marked by a giant elliptical galaxy which is also a known radio source. Thus it is very likely that we observe one of the interaction systems where the central cluster AGN is heating the cooling core region in a self-regulated way to prevent a massive cooling of the gas, similar to several such cases studied in detail in more nearby clusters. The interest raised by this system is then due to the high power recycled in RXCJ1504-0248 over cooling time scales which is about one order of magnitude higher than what occurs in the studied, nearby cooling core clusters. The cluster is also found to be very massive, with a global X-ray temperature of about 10.5 keV and a total mass of about 1.7 10e15 Msun inside 3 Mpc.Comment: accepted for publication in Astrophys. Journal, 10 figure