180 research outputs found
Changes in Tendon Thickness only Occurs in Patients with Achilles Tendinopathy
A previous George Fox Study examined the effect of a heavy load eccentric exercise program for patients with achilles tendinopathy (AT) to test the hypothesis of improved outcomes and decreased tendon thickness
The Ultraviolet and Infrared Star Formation Rates of Compact Group Galaxies: An Expanded Sample
Compact groups of galaxies provide insight into the role of low-mass, dense
environments in galaxy evolution because the low velocity dispersions and close
proximity of galaxy members result in frequent interactions that take place
over extended timescales. We expand the census of star formation in compact
group galaxies by \citet{tzanavaris10} and collaborators with Swift UVOT,
Spitzer IRAC and MIPS 24 \micron\ photometry of a sample of 183 galaxies in 46
compact groups. After correcting luminosities for the contribution from old
stellar populations, we estimate the dust-unobscured star formation rate
(SFR) using the UVOT uvw2photometry. Similarly, we use the MIPS
24 \micron\ photometry to estimate the component of the SFR that is obscured by
dust (SFR). We find that galaxies which are MIR-active
(MIR-"red"), also have bluer UV colours, higher specific star formation rates,
and tend to lie in H~{\sc i}-rich groups, while galaxies that are MIR-inactive
(MIR-"blue") have redder UV colours, lower specific star formation rates, and
tend to lie in H~{\sc i}-poor groups. We find the SFRs to be continuously
distributed with a peak at about 1 M yr, indicating this might
be the most common value in compact groups. In contrast, the specific star
formation rate distribution is bimodal, and there is a clear distinction
between star-forming and quiescent galaxies. Overall, our results suggest that
the specific star formation rate is the best tracer of gas depletion and galaxy
evolution in compact groups.Comment: 19 pages, 17 figure
Global Properties of Neutral Hydrogen in Compact Groups
Compact groups of galaxies provide a unique environment to study the
evolution of galaxies amid frequent gravitational encounters. These nearby
groups have conditions similar to those in the earlier universe when galaxies
were assembled and give us the opportunity to witness hierarchical formation in
progress. To understand how the compact group environment affects galaxy
evolution, we examine the gas and dust in these groups. We present new
single-dish GBT neutral hydrogen (HI) observations of 30 compact groups and
define a new way to quantify the group HI content as the HI-to-stellar mass
ratio of the group as a whole. We compare the HI content with mid-IR indicators
of star formation and optical [g-r] color to search for correlations between
group gas content and star formation activity of individual group members.
Quiescent galaxies tend to live in HI-poor groups, and galaxies with active
star formation are more commonly found in HI-rich groups. Intriguingly, we also
find "rogue" galaxies whose star formation does not correlate with group HI
content. In particular, we identify three galaxies (NGC 2968 in RSCG 34, KUG
1131+202A in RSCG 42, and NGC 4613 in RSCG 64) whose mid-IR activity is
discrepant with the HI. We speculate that this mismatch between mid-IR activity
and HI content is a consequence of strong interactions in this environment that
can strip HI from galaxies and abruptly affect star-formation. Ultimately,
characterizing how and on what timescales the gas is processed in compact
groups will help us understand the interstellar medium in complex, dense
environments similar to the earlier Universe.Comment: Accepted to A
Some Like It Hot: Linking Diffuse X-ray Luminosity, Baryonic Mass, and Star Formation Rate in Compact Groups of Galaxies
We present an analysis of the diffuse X-ray emission in 19 compact groups of
galaxies (CGs) observed with Chandra. The hottest, most X-ray luminous CGs
agree well with the galaxy cluster X-ray scaling relations in and
, even in CGs where the hot gas is associated with only the
brightest galaxy. Using Spitzer photometry, we compute stellar masses and
classify HCGs 19, 22, 40, and 42 and RSCGs 32, 44, and 86 as fossil groups
using a new definition for fossil systems that includes a broader range of
masses. We find that CGs with total stellar and HI masses
M are often X-ray luminous, while lower-mass CGs only sometimes exhibit
faint, localized X-ray emission. Additionally, we compare the diffuse X-ray
luminosity against both the total UV and 24 m star formation rates of each
CG and optical colors of the most massive galaxy in each of the CGs. The most
X-ray luminous CGs have the lowest star formation rates, likely because there
is no cold gas available for star formation, either because the majority of the
baryons in these CGs are in stars or the X-ray halo, or due to gas stripping
from the galaxies in CGs with hot halos. Finally, the optical colors that trace
recent star formation histories of the most massive group galaxies do not
correlate with the X-ray luminosities of the CGs, indicating that perhaps the
current state of the X-ray halos is independent of the recent history of
stellar mass assembly in the most massive galaxies.Comment: 20 pages, 7 figures, accepted for publication in Ap
Alphaflexivirus genomes in stony coral tissue loss disease-affected, disease-exposed, and disease-unexposed coral colonies in the U.S. Virgin Islands
© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Veglia, A., Beavers, K., Van Buren, E., Meiling, S., Muller, E., Smith, T., Holstein, D., Apprill, A., Brandt, M., Mydlarz, L., & Correa, A. Alphaflexivirus genomes in stony coral tissue loss disease-affected, disease-exposed, and disease-unexposed coral colonies in the U.S. Virgin Islands. Microbiology Resource Announcements, 11(2), (2022): e01199–e01121, https://doi.org/10.1128/mra.01199-21.Stony coral tissue loss disease (SCTLD) is decimating Caribbean corals. Here, through the metatranscriptomic assembly and annotation of two alphaflexivirus-like strains, we provide genomic evidence of filamentous viruses in SCTLD-affected, -exposed, and -unexposed coral colonies. These data will assist in clarifying the roles of viruses in SCTLD.This work was supported by the National Science Foundation (Biological Oceanography) award numbers 1928753 to M.E.B. and T.B.S., 1928609 to A.M.S.C., 1928817 to E.M.M., 19228771 to L.D.M., 1927277 to D.M.H., and 1928761 to A.A., as well as by VI EPSCoR (NSF numbers 0814417 and 1946412)
Laboratory Demonstration of Spatial Linear Dark Field Control For Imaging Extrasolar Planets in Reflected Light
Imaging planets in reflected light, a key focus of future NASA missions and
ELTs, requires advanced wavefront control to maintain a deep, temporally
correlated null of stellar halo -- i.e. a dark hole -- at just several
diffraction beam widths. Using the Ames Coronagraph Experiment testbed, we
present the first laboratory tests of Spatial Linear Dark Field Control (LDFC)
approaching raw contrasts ( 510) and separations (1.5--5.2
/D) needed to image jovian planets around Sun-like stars with
space-borne coronagraphs like WFIRST-CGI and image exo-Earths around low-mass
stars with future ground-based 30m class telescopes. In four separate
experiments and for a range of different perturbations, LDFC largely restores
(to within a factor of 1.2--1.7) and maintains a dark hole whose contrast is
degraded by phase errors by an order of magnitude. Our implementation of
classical speckle nulling requires a factor of 2--5 more iterations and 20--50
DM commands to reach contrasts obtained by spatial LDFC. Our results provide a
promising path forward to maintaining dark holes without relying on DM probing
and in the low-flux regime, which may improve the duty cycle of high-contrast
imaging instruments, increase the temporal correlation of speckles, and thus
enhance our ability to image true solar system analogues in the next two
decades.Comment: 13 pages, 7 figures, accepted for publication in Publications of the
Astronomical Society of the Pacifi
Intragroup and Galaxy-linked Diffuse X-ray Emission In Hickson Compact Groups
Isolated compact groups (CGs) of galaxies present a range of dynamical states, group velocity dispersions, and galaxy morphologies with which to study galaxy evolution, particularly the properties of gas both within the galaxies and in the intragroup medium. As part of a large, multiwavelength examination of CGs, we present an archival study of diffuse X-ray emission in a subset of nine Hickson compact groups (HCGs) observed with the Chandra X-Ray Observatory. We find that seven of the groups in our sample exhibit detectable diffuse emission. However, unlike large-scale emission in galaxy clusters, the diffuse features in the majority of the detected groups are linked to the individual galaxies, in the form of both plumes and halos likely as a result of vigourous star formation or activity in the galaxy nucleus, as well as in emission from tidal features. Unlike previous studies from earlier X-ray missions, HCGs 31, 42, 59, and 92 are found to be consistent with the L(sub X-Tau) relationship from clusters within the errors, while HCGs 16 and 31 are consistent with the cluster L(sub X-sigma) relation, though this is likely coincidental given that the hot gas in these two systems is largely due to star formation. We find that L(sub X) increases with decreasing group Hi to dynamical-mass ratio with tentative evidence for a dependence in X-ray luminosity on Hi morphology whereby systems with intragroup Hi indicative of strong interactions are considerably more X-ray luminous than passively evolving groups. We also find a gap in the L(sub X) of groups as a function of the total group specific star formation rate. Our findings suggest that the hot gas in these groups is not in hydrostatic equilibrium and these systems are not low-mass analogs of rich groups or clusters, with the possible exception of HCG 62
Reverberation Mapping of the Kepler-Field AGN KA1858+4850
KA1858+4850 is a narrow-line Seyfert 1 galaxy at redshift 0.078 and is among the brightest active galaxies monitored by the Kepler mission. We have carried out a reverberation mapping campaign designed to measure the broad-line region size and estimate the mass of the black hole in this galaxy. We obtained 74 epochs of spectroscopic data using the Kast Spectrograph at the Lick 3-m telescope from February to November of 2012, and obtained complementary V-band images from five other ground-based telescopes. We measured the Hbeta light curve lag with respect to the V-band continuum light curve using both cross-correlation techniques (CCF) and continuum light curve variability modeling with the JAVELIN method, and found rest-frame lags of CCF = 13.53+2.03 2.32 days and JAVELIN = 13.15+1.08 1.00 days. The Hbeta root-mean-square line profile has a width of sigma line = 770 +/- 49 km s(exp -1). Combining these two results and assuming a virial scale factor of f = 5.13, we obtained a virial estimate of M(sub BH) = 8.06+1.59 1.72 10(exp 6) solar mass for the mass of the central black hole and an Eddington ratio of L/L(sub Edd) (is) approx. 0.2. We also obtained consistent but slightly shorter emission-line lags with respect to the Kepler light curve. Thanks to the Kepler mission, the light curve of KA1858+4850 has among the highest cadences and signal-to-noise ratios ever measured for an active galactic nucleus; thus, our black hole mass measurement will serve as a reference point for relations between black hole mass and continuum variability characteristics in active galactic nuclei
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