Evolution of Cluster Ellipticals at 0.2 < z < 1.2 from Hubble Space Telescope Imaging

Two-dimensional surface photometry derived from Hubble Space Telescope imaging is presented for a sample of 225 early-type galaxies (assumed to be cluster members) in the fields of 9 clusters at redshifts $0.17 < z < 1.21$. The 94 luminous ellipticals ($M_{AB}(B)<-20$; selected by morphology alone with no reference to color) form tight sequences in the size-luminosity plane. The position of these sequences shifts, on average, with redshift so that an object of a given size at z=0.55 is brighter by $\Delta M(B)=-0.57 \pm 0.13$ mag than its counterpart (measured with the same techniques) in nearby clusters. At z=0.9 the shift is $\Delta M(B)=-0.96 \pm 0.22$ mag. If the relation between size and luminosity is universal so that the local cluster galaxies represent the evolutionary endpoints of those at high redshift, and if the size-luminosity relation is not modified by dynamical processes then this population of galaxies has undergone significant luminosity evolution since z=1 consistent with expectations based on models of passively evolving, old stellar populations.Comment: 7 pages, 3 figures, and 1 Tabl

Use of Counter-balanced Smith Machine Affects Performance Measurements for Rebound Bench Press Throws

Rebound bench presses throws (RBT), often performed on a Smith machine, are used for assessment and training of upper body power. During a RBT, the stretch-shortening cycle potentiates performance in the concentric movement. Smith machines frequently utilize a counter-balance weight to reduce the net load on the barbell; however, the use of counter-balance weight affects measures of performance for RBT. PURPOSE: To evaluate how the use of a counter-balanced Smith machine affects performance measures for RBT. METHODS: Performance measures for the no counter-balanced (NCB) and counter-balanced (CB) RBT were assessed for 24 men (age: 23 ± 3 years, height: 179 ± 6 cm, mass: 91 ± 17 kg, bench press 1-repetition maximum [1RM]: 107 ± 18 kg). Each participant performed 2 sets of 2 repetitions of RBT for each condition at 30 % of their 1RM. Peak power, peak force, peak concentric and eccentric velocities, and duration of eccentric and concentric phases were measured using a linear accelerometer attached to the barbell; peak ground reaction force (GRF) was measured using a force plate. For each condition, data from the repetition with the highest peak power was used in further analyses. Peak EMG was measured for the right pectoral, deltoid and triceps muscles and normalized using peak EMG in the 1RM. RESULTS: Peak barbell measurements for power (NCB: 1220 ± 269 W, CB: 1069 ± 255 W), force (NCB: 906 ± 252 N, CB: 713 ± 143 N), and concentric (NCB: 2.54 ± 0.27 m•s-1, CB: 2.24 ± 0.32 m•s-1) and eccentric (NCB: -1.19 ± 0.46 m•s-1, CB: -0.95 ± 0.29 m•s-1) velocities were significantly (p\u3c0.05) higher for NCB compared to CB. The durations for the eccentric (NCB: 0.53 ± 0.16 s, CB: 0.64 ± 0.12 s) and concentric phases (NCB: 0.58 ± 0.58 s, CB: 0.77 ± 0.82 s), and peak pectoral EMG (NCB: 91 ± 21 % of 1RM, CB: 101 ± 24 % of 1RM) were lower for NCB compared to CB. Peak EMG for deltoid and triceps and peak GRF were unaffected by the use of counter-balance weights. CONCLUSION: The use of CB equipment resulted in reduced performance measurements (peak power, peak force, and peak eccentric and concentric velocities) for the RBT compared to NCB equipment. The lower peak eccentric stretch velocity likely resulted in a less effective stretch-shortening cycle for CB compared to NCB and thus helps explain the lower performance measurements found for CB

The overdensities of galaxy environments as a function of luminosity and color

We study the mean environments of galaxies in the Sloan Digital Sky Survey as a function of rest-frame luminosity and color. Overdensities in galaxy number are estimated in $8 h^{-1} \mathrm{Mpc}$ and $1 h^{-1} \mathrm{Mpc}$ spheres centered on $125,000$ galaxies taken from the SDSS spectroscopic sample. We find that, at constant color, overdensity is independent of luminosity for galaxies with the blue colors of spirals. This suggests that, at fixed star-formation history, spiral-galaxy mass is a very weak function of environment. Overdensity does depend on luminosity for galaxies with the red colors of early types; both low-luminosity and high-luminosity red galaxies are found to be in highly overdense regions.Comment: submitted to ApJ

Effect of Using a Counter-balanced Smith Machine on Performance Measurements for Concentric-Only Bench Press Throws

Bench press throws using a Smith machine are often used for assessment and training of upper body power. Concentric only bench press throws (CON-BT) provide important information on an individual’s ability to produce force from a static start. Smith machines often utilize a counter-balance weight system to reduce the net load on the barbell; however, it is not known how counter-balance weight affects measurements of performance during a CON-BT. PURPOSE: To examine the effect of a counter-balance weight on CON-BT performance measurements. METHODS: 24 men (age: 23 ± 3 years, height: 179 ± 6 cm, mass: 91 ± 17 kg, bench press 1-repetition maximum [1RM]: 107 ± 18 kg) performed 2 sets of 2 repetitions of CON-BT at 30% of their 1RM using a no counter-balanced (NCB) and a counter-balanced (CB) Smith machine. Total duration, peak power, peak force, and peak velocity were measured using a linear accelerometer attached to the barbell; peak ground reaction force (GRF) was measured using a force plate. For each condition, data from the repetition with the highest peak power was used for further analyses. Peak EMG was measured for the right pectoral, deltoid and triceps muscles and normalized using peak EMG in the 1RM. RESULTS: Measurements for peak barbell power (NCB: 1169 ± 260 W, CB: 938 ± 262 W) and force (NCB: 695 ± 129 N, CB: 577 ± 134 N) were significantly greater (p\u3c0.05) for NCB compared to CB. The total duration of CON-BT was shorter for NCB (0.62 ± 0.41 s) compared to CB (0.78 ± 0.50 s). The peak GRF showed a trend (p\u3c0.10) for being lower for NCB (884 ± 213 N] compared to CB [912 ± 190 N). Peak EMG and peak velocity were unaffected by the use of counter-balance weight. CONCLUSION: The use of a CB Smith machine reduced barbell performance measurements (peak power and peak force) but increased the peak GRF during a CON-BT. A counter-balance weight becomes ineffective and the net external load increases during the CON-BT when the barbell accelerates faster than the gravitational constant pulls on the counter weight, thus explaining the lower performance measurements found for CB

Tracking Down a Critical Halo Mass for Killing Galaxies through the Growth of the Red-Sequence

Red-sequence galaxies record the history of terminated star-formation in the Universe and can thus provide important clues to the mechanisms responsible for this termination. We construct composite samples of published cluster and field galaxy photometry in order to study the build-up of galaxies on the red-sequence, as parameterised by the dwarf-to-giant ratio (DGR). We find that the DGR in clusters is higher than that of the field at all redshifts, implying that the faint end of the red-sequence was established first in clusters. We find that the DGR evolves with redshift for both samples, consistent with the ``down-sizing'' picture of star formation. We examine the predictions of semi-analytic models for the DGR and find that neither the magnitude of its environmental dependence nor its evolution is correctly predicted in the models. Red-sequence DGRs are consistently too high in the models, the most likely explanation being that the strangulation mechanism used to remove hot gas from satellite galaxies is too efficient. Finally we present a simple toy model including a threshold mass, below which galaxies are not strangled, and show that this can predict the observed evolution of the field DGR.Comment: MNRAS letters accepted. 5 pages, 1 figur

Chemical evolution of the intra-cluster medium

The high metallicity of the intra-cluster medium (ICM) is generally interpreted on the base of the galactic wind scenario for elliptical galaxies. In this framework, we develop a toy-model to follow the chemical evolution of the ICM, formulated in analogy to chemical models for individual galaxies. The model computes the galaxy formation history (GFH) of cluster galaxies, connecting the final luminosity function (LF) to the corresponding metal enrichment history of the ICM. The observed LF can be reproduced with a smooth, Madau-plot like GFH peaking at z~ 1-2, plus a "burst" of formation of dwarf galaxies at high redshift. The model is used to test the response of the predicted metal content and abundance evolution of the ICM to varying input galactic models. The chemical enrichment is computed from "galactic yields" based on models of elliptical galaxies with a variable initial mass function (IMF), favouring the formation of massive stars at high redshift and/or in more massive galaxies. For a given final galactic luminosity, these model ellipticals eject into the ICM a larger quantity of gas and of metals than do standard models based on the Salpeter IMF. However, a scenario in which the IMF varies with redshift as a consequence of the effect of the the cosmic background temperature on the Jeans mass scale, appears to be too mild to account for the observed metal production in clusters. The high iron-mass-to-luminosity-ratio of the ICM can be reproduced only by assuming a more dramatic variation of the typical stellar mass, in line with other recent findings. The mass in the wind-ejected gas is predicted to exceed the mass in galaxies by a factor of 1.5-2 and to constitute roughly half of the intra-cluster gas.Comment: 25 pages, 17 figures, accepted for publication in A&

The Hubble Space Telescope Wide Field Camera 3 Early Release Science data: Panchromatic Faint Object Counts for 0.2-2 microns wavelength

We describe the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Early Release Science (ERS) observations in the Great Observatories Origins Deep Survey (GOODS) South field. The new WFC3 ERS data provide calibrated, drizzled mosaics in the UV filters F225W, F275W, and F336W, as well as in the near-IR filters F098M (Ys), F125W (J), and F160W (H) with 1-2 HST orbits per filter. Together with the existing HST Advanced Camera for Surveys (ACS) GOODS-South mosaics in the BViz filters, these panchromatic 10-band ERS data cover 40-50 square arcmin at 0.2-1.7 {\mu}m in wavelength at 0.07-0.15" FWHM resolution and 0.090" Multidrizzled pixels to depths of AB\simeq 26.0-27.0 mag (5-{\sigma}) for point sources, and AB\simeq 25.5-26.5 mag for compact galaxies. In this paper, we describe: a) the scientific rationale, and the data taking plus reduction procedures of the panchromatic 10-band ERS mosaics; b) the procedure of generating object catalogs across the 10 different ERS filters, and the specific star-galaxy separation techniques used; and c) the reliability and completeness of the object catalogs from the WFC3 ERS mosaics. The excellent 0.07-0.15" FWHM resolution of HST/WFC3 and ACS makes star- galaxy separation straightforward over a factor of 10 in wavelength to AB\simeq 25-26 mag from the UV to the near-IR, respectively.Comment: 51 pages, 71 figures Accepted to ApJS 2011.01.2

Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey: Report of a Community Workshop Examining Extragalactic, Galactic, Stellar and Planetary Science

SPHEREx is a proposed SMEX mission selected for Phase A. SPHEREx will carry out the first all-sky spectral survey and provide for every 6.2" pixel a spectra between 0.75 and 4.18 $\mu$m [with R$\sim$41.4] and 4.18 and 5.00 $\mu$m [with R$\sim$135]. The SPHEREx team has proposed three specific science investigations to be carried out with this unique data set: cosmic inflation, interstellar and circumstellar ices, and the extra-galactic background light. It is readily apparent, however, that many other questions in astrophysics and planetary sciences could be addressed with the SPHEREx data. The SPHEREx team convened a community workshop in February 2016, with the intent of enlisting the aid of a larger group of scientists in defining these questions. This paper summarizes the rich and varied menu of investigations that was laid out. It includes studies of the composition of main belt and Trojan/Greek asteroids; mapping the zodiacal light with unprecedented spatial and spectral resolution; identifying and studying very low-metallicity stars; improving stellar parameters in order to better characterize transiting exoplanets; studying aliphatic and aromatic carbon-bearing molecules in the interstellar medium; mapping star formation rates in nearby galaxies; determining the redshift of clusters of galaxies; identifying high redshift quasars over the full sky; and providing a NIR spectrum for most eROSITA X-ray sources. All of these investigations, and others not listed here, can be carried out with the nominal all-sky spectra to be produced by SPHEREx. In addition, the workshop defined enhanced data products and user tools which would facilitate some of these scientific studies. Finally, the workshop noted the high degrees of synergy between SPHEREx and a number of other current or forthcoming programs, including JWST, WFIRST, Euclid, GAIA, K2/Kepler, TESS, eROSITA and LSST.Comment: Report of the First SPHEREx Community Workshop, http://spherex.caltech.edu/Workshop.html , 84 pages, 28 figure

Normative Alethic Pluralism

Some philosophers have argued that truth is a norm of judgement and have provided a variety of formulations of this general thesis. In this paper, I shall side with these philosophers and assume that truth is a norm of judgement. What I am primarily interested in here are two core questions concerning the judgement-truth norm: (i) what are the normative relationships between truth and judgement? And (ii) do these relationships vary or are they constant? I argue for a pluralist picture—what I call Normative Alethic Pluralism (NAP)—according to which (i) there is more than one correct judgement-truth norm and (ii) the normative relationships between truth and judgement vary in relation to the subject matter of the judgement. By means of a comparative analysis of disagreement in three areas of the evaluative domain—refined aesthetics, basic taste and morality—I show that there is an important variability in the normative significance of disagreement—I call this the variability conjecture. By presenting a variation of Lynch’s scope problem for alethic monism, I argue that a monistic approach to the normative function of truth is unable to vindicate the conjecture. I then argue that normative alethic pluralism provides us with a promising model to account for it