The ASTRA Spectrophotometer: A July 2004 Progress Report

A cross-dispersed spectrophotometer with CCD detector and its automated 0.5-m telescope at the Fairborn Observatory, now under construction, should begin observations in 6 to 9 months. The Citadel ASTRA Telescope will be able to observe Vega the primary standard, make rapid measurements of the naked-eye stars, use 10 minutes per hour to obtain photometric measurements of the nightly extinction, and obtain high quality observations of V=10.5 mag. stars in an hour. The approximate wavelength range is 3300-9000A with a resolution of 14A in first and 7A in second order. Filter photometric magnitudes and indices will be calibrated in part for use as quality checks. Science observations for major projects such as comparisons with model atmospheres codes and for exploratory investigations should also begin in the first year. The ASTRA team realizes to deal with this potential data flood that they will need help to make the best scientific uses of the data. Thus they are interested in discussing possible collaborations. In less than a year of normal observing, all isolated stars in the Bright Star Catalog that can be observed can have their fluxes well measured. Some A Star related applications are discussed.Comment: 10 pages, 4 figures. Poster presented at IAU Symposium 224 "The A Star Puzzle", 7-13 July 2004, Poprad, Slovaki

Evolution of the Cluster Mass and Correlation Functions in LCDM Cosmology

The evolution of the cluster mass function and the cluster correlation function from z = 0 to z = 3 are determined using 10^6 clusters obtained from high-resolution simulations of the current best-fit LCDM cosmology (\Omega_m = 0.27, \sigma_8 = 0.84, h = 0.7). The results provide predictions for comparisons with future observations of high redshift clusters. A comparison of the predicted mass function of low redshift clusters with observations from early Sloan Digital Sky Survey data, and the predicted abundance of massive distant clusters with observational results, favor a slightly larger amplitude of mass fluctuations (\sigma_8 = 0.9) and lower density parameter (\Omega_m = 0.2); these values are consistent within 1-\sigma with the current observational and model uncertainties. The cluster correlation function strength increases with redshift for a given mass limit; the clusters were more strongly correlated in the past, due to their increasing bias with redshift - the bias reaches b = 100 at z = 2 for M > 5 x 10^13 h^-1 M_sun. The richness-dependent cluster correlation function, represented by the correlation scale versus cluster mean separation relation, R0-d, is generally consistent with observations. This relation can be approximated as R_0 = 1.7 d^0.6 h^-1 Mpc for d = 20 - 60 h^-1 Mpc. The R0-d relation exhibits surprisingly little evolution with redshift for z < 2; this can provide a new test of the current LCDM model when compared with future observations of high redshift clusters.Comment: 20 pages, 9 figures, accepted for publication in Ap

Constraining Cosmic Evolution of Type Ia Supernovae

We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 UV spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with the same slit width, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be ~0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of ~3% in the optical and growing toward the UV. The difference between the maximum light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.Comment: 22 pages, 22 figures, submitted to ApJ. Composite spectra can be downloaded from http://astro.berkeley.edu/~rfoley/composite

The Relationship between 60-yard sprint, 30-yard sprint, Standardized Base Stealing Sprint, and Offensive Baseball Performance

Athletic performance testing protocols strive to accurately predicting or gain better understanding of an athlete’s performance within a particular sport or game. Regarding baseball, Wolfe and colleagues (2012) examined the predictive validity of the 60-yard shuttle run on pitching performance and concluded that strikeouts and innings pitched were significantly related to elevated kinetic energy factors of pitchers obtained from the shuttle run performance. Concerning for baseball position players, the 60-yard sprint (60YS) is traditionally utilized to showcase “baseball speed”, with minimal empirical evident supporting predictability to baseball specific performance outcomes. PURPOSE: The aim of the current investigation was to have examine the relationship between 60YS and offensive baseball performance outcomes, as well as the 30-yard sprint (30YS) test, and newly created standardized 1st to 2nd sprint (STS) test relationship to offensive baseball performance outcomes. METHODS: Division I baseball position players (n = 17; height: 180.92 ± 5.61 cm; weight: 82.1 ± 11.12 kg) performed three sprinting tests: 60YS, 30YS, and STS. Each test was recorded using the Brower Timing Gate System, with sprint time recorded in second. All testing was completed prior to the first game of the team’s college baseball season. Offensive baseball performance measures were recorded throughout 61 regular season games. The following baseball performance data was collected from the university’s official NCAA game performance website: total stolen bases (SB), stole base attempts (AT), stolen base percentage (SBP), at bats (AB), hits (H), doubles (DB), triples (TR), homeruns (HR), runs (R), base-on-balls (BB), hit by pitch (HBP), on base percentage (OBP), slugging percentage (SLP), touched bases (TB), runs batted in (RBI), and batting average (AVE). Pearson’s product-moment correlation (p \u3c .05) was employed to examine the correlation between sprint tests and offensive baseball performance. RESULTS: The statistical analysis revealed significant correlations between STS (p = .002, r = -.762), 30 yd sprint (p = .048, r = -.556), and 60 yd sprint (p = .038, r = -.578) and SB. Additionally, a significant correlation was identified between OBP and STS (p = .022, r = -.625), 30YS (p = .027, r = -.609), and 60YS (p = .020, r = -.633). Aside from these two baseball performance metrics, 30YS and 60YS had no significant correlation with baseball performance. However, STS, additionally, significantly (p \u3c .05) correlated with AT, AB, H, TR, HR, R, BB, SLP, TB, RBI, and AVE. CONCLUSION: The STS, 30YS, and 60YS had a significant relationship with offensive baseball performance. However, the results of 30YS and 60YS only correlated with two offensive measures, while STS had a significant correlation with all but 3 offensive performance metrics. These findings suggest STS may be a more relevant measure for predicting offensive baseball performance than the traditional 30YS and 60YS tests

EXCITATION of COUPLED STELLAR MOTIONS in the GALACTIC DISK by ORBITING SATELLITES

We use a set of high-resolution N-body simulations of the Galactic disk to study its interactions with the population of cosmologically predicted satellites. One simulation illustrates that multiple passages of massive satellites with different velocities through the disk generate a wobble, which has the appearance of rings in face-on projections of the stellar disk. They also produce flares in the outer disk parts and gradually heat the disk through bending waves. A different numerical experiment shows that an individual satellite as massive as the Sagittarius dwarf galaxy passing through the disk will drive coupled horizontal and vertical oscillations of stars in underdense regions with small associated heating. This experiment shows that vertical excursions of stars in these low-density regions can exceed 1 kpc in the Solar neighborhood, resembling the recently locally detected coherent vertical oscillations. They can also induce non-zero vertical streaming motions as large as 10-20 km s-1, which is consistent with recent observations in the Galactic disk. This phenomenon appears as a local ring with modest associated disk heating. © 2016. The American Astronomical Society. All rights reserved

Unveiling the Nature of Submillimeter Galaxy SXDF850.6

We present an 880 micron Submillimeter Array (SMA) detection of the submillimeter galaxy SXDF850.6. SXDF850.6 is a bright source (S(850 micron) = 8 mJy) detected in the SCUBA Half Degree Extragalactic Survey (SHADES), and has multiple possible radio counterparts in its deep radio image obtained at the VLA. Our new SMA detection finds that the submm emission coincides with the brightest radio emission that is found ~8" north of the coordinates determined from SCUBA. Despite the lack of detectable counterparts in deep UV/optical images, we find a source at the SMA position in near-infrared and longer wavelength images. We perform SED model fits to UV-optical-IR photometry (u, B, V, R, i', z', J, H, K, 3.6 micron, 4.5 micron, 5.8 micron, and 8.0 micron) and to submm-radio photometry (850 micron, 880 micron, 1100 micron, and 21 cm) independently, and we find both are well described by starburst templates at a redshift of z ~= 2.2 (+/- 0.3). The best-fit parameters from the UV-optical-IR SED fit are a redshift of z = 1.87 (+0.15/-0.07), a stellar mass of M_star = 2.5 +2.2/-0.3 x 10^11 M_sun, an extinction of A_V = 3.0 (+0.3/-1.0) mag, and an age of 720 (+1880/-210) Myr. The submm-radio SED fit provides a consistent redshift of z ~ 1.8-2.5, an IR luminosity of L_IR = (7-26) x 10^12 L_sun, and a star formation rate of 1300-4500 M_sun/yr. These results suggest that SXDF850.6 is a mature system already having a massive amount of old stellar population constructed before its submm bright phase and is experiencing a dusty starburst, possibly induced by major mergers.Comment: 7 pages, 5 figures, Accepted for publication in Astrophysical Journa

The physical scale of the far-infrared emission in the most luminous submillimetre galaxies II: evidence for merger-driven star formation

We present high-resolution 345 GHz interferometric observations of two extreme luminous (L_{IR}>10^{13} L_sun), submillimetre-selected galaxies (SMGs) in the COSMOS field with the Submillimeter Array (SMA). Both targets were previously detected as unresolved point-sources by the SMA in its compact configuration, also at 345 GHz. These new data, which provide a factor of ~3 improvement in resolution, allow us to measure the physical scale of the far-infrared in the submillimetre directly. The visibility functions of both targets show significant evidence for structure on 0.5-1 arcsec scales, which at z=1.5 translates into a physical scale of 5-8 kpc. Our results are consistent with the angular and physical scales of two comparably luminous objects with high-resolution SMA followup, as well as radio continuum and CO sizes. These relatively compact sizes (<5-10 kpc) argue strongly for merger-driven starbursts, rather than extended gas-rich disks, as the preferred channel for forming SMGs. For the most luminous objects, the derived sizes may also have important physical consequences; under a series of simplifying assumptions, we find that these two objects in particular are forming stars close to or at the Eddington limit for a starburst.Comment: 9 pages, 3 Figures, submitted to MNRA

AzTEC Millimetre Survey of the COSMOS Field - II. Source Count Overdensity and Correlations with Large-Scale Structure

We report an over-density of bright sub-millimetre galaxies (SMGs) in the 0.15 sq. deg. AzTEC/COSMOS survey and a spatial correlation between the SMGs and the optical-IR galaxy density at z <~ 1.1. This portion of the COSMOS field shows a ~ 3-sigma over-density of robust SMG detections when compared to a background, or "blankfield", population model that is consistent with SMG surveys of fields with no extragalactic bias. The SMG over-density is most significant in the number of very bright detections (14 sources with measured fluxes S(1.1mm) > 6 mJy), which is entirely incompatible with sample variance within our adopted blank-field number densities and infers an over-density significance of >> 4. We find that the over-density and spatial correlation to optical-IR galaxy density are most consistent with lensing of a background SMG population by foreground mass structures along the line of sight, rather than physical association of the SMGs with the z <~ 1.1 galaxies/clusters. The SMG positions are only weakly correlated with weak-lensing maps, suggesting that the dominant sources of correlation are individual galaxies and the more tenuous structures in the region and not the massive and compact clusters. These results highlight the important roles cosmic variance and large-scale structure can play in the study of SMGs.Comment: 12 pages, 11 figures, 2 tables, accepted for publication in MNRA

AzTEC millimeter survey of the COSMOS field - III. Source catalog over 0.72 sq. deg. and plausible boosting by large-scale structure

We present a 0.72 sq. deg. contiguous 1.1mm survey in the central area of the COSMOS field carried out to a 1sigma ~ 1.26 mJy/beam depth with the AzTEC camera mounted on the 10m Atacama Submillimeter Telescope Experiment (ASTE). We have uncovered 189 candidate sources at a signal-to-noise ratio S/N >= 3.5, out of which 129, with S/N >= 4, can be considered to have little chance of being spurious (< 2 per cent). We present the number counts derived with this survey, which show a significant excess of sources when compared to the number counts derived from the ~0.5 sq. deg. area sampled at similar depths in the Scuba HAlf Degree Extragalactic Survey (SHADES, Austermann et al. 2010). They are, however, consistent with those derived from fields that were considered too small to characterize the overall blank-field population. We identify differences to be more significant in the S > 5 mJy regime, and demonstrate that these excesses in number counts are related to the areas where galaxies at redshifts z < 1.1 are more densely clustered. The positions of optical-IR galaxies in the redshift interval 0.6 < z < 0.75 are the ones that show the strongest correlation with the positions of the 1.1mm bright population (S > 5 mJy), a result which does not depend exclusively on the presence of rich clusters within the survey sampled area. The most likely explanation for the observed excess in number counts at 1.1mm is galaxy-galaxy and galaxy-group lensing at moderate amplification levels, that increases in amplitude as one samples larger and larger flux densities. This effect should also be detectable in other high redshift populations.Comment: 21 pages, 17 figures, accepted for publication in MNRA