3,236 research outputs found
Optical Spectroscopic Survey of High-latitude WISE-selected Sources
We report on the results of an optical spectroscopic survey at high Galactic latitude (|b| ≥ 30°) of a sample of WISE-selected targets, grouped by WISE W1 (λ_eff = 3.4 μm) flux, which we use to characterize the sources WISE detected. We observed 762 targets in 10 disjoint fields centered on ultraluminous infrared galaxy candidates using DEIMOS on Keck II. We find 0.30 ± 0.02 galaxies arcmin–2 with a median redshift of z = 0.33 ± 0.01 for the sample with W1 ≥ 120 μJy. The foreground stellar densities in our survey range from 0.23 ± 0.07 arcmin–2 to 1.1 ± 0.1 arcmin–2 for the same sample. We obtained spectra that produced science grade redshifts for ≥90% of our targets for sources with W1 flux ≥120 μJy that also had an i-band flux gsim 18 μJy. We used this for targeting very preliminary data reductions available to the team in 2010 August. Our results therefore present a conservative estimate of what is possible to achieve using WISE's Preliminary Data Release for the study of field galaxies
Clinical and serological studies of tuberculosis patients in Argentina receiving immunotherapy with Mycobacterium vaccae (SRL 172)
AbstractTwo small, placebo-controlled studies of immunotherapy with heat killed Mycobacterium vaccae added to routine chemotherapy for pulmonary tuberculosis, together involving 40 HIV seronegative patients, were carried out in Argentina. The immunotherapy was associated with reduced sputum smear positivity of AFB at 1 month and a greater reduction in ESR at 2 months. In the first study radiological improvement was better (P < 0·05) among immunotherapy recipients. In the second study, weight regain and time to become apyrexial were measured and were found to be improved amongst immunotherapy recipients (P < 0·05).In the first month of treatment the levels of IgG to the 65 kDa and 70 kDa heat-shock proteins showed greater falls following immunotherapy (P < 0·05 and P < 0·001, respectively). On admission serum cytokine levels of interleukins 4 and 10 (IL-4, IL-10), interferon gamma (IFN-γ) and tumour necrosis factor alpha (TNF-α) were grossly raised in comparison with a matched control group (P < 0·001). After 1 month. Levels of IL-4, IL-10 and TNF-α fell (P < 0·001, P < 0·01 and P < 0·01, respectively) and levels of IFN-γ rose more (P = 0·005) in immunotherapy recipients than in those receiving chemotherapy alone. The results are in accord with a switch towards a TH1 immunological status and clinical benefit for immunotherapy recipients
A Sr-Rich Star on the Main Sequence of Omega Centauri
Abundance ratios relative to iron for carbon, nitrogen, strontium and barium
are presented for a metal-rich main sequence star ([Fe/H]=--0.74) in the
globular cluster omega Centauri. This star, designated 2015448, shows depleted
carbon and solar nitrogen, but more interestingly, shows an enhanced abundance
ratio of strontium [Sr/Fe] ~ 1.6 dex, while the barium abundance ratio is
[Ba/Fe]<0.6 dex. At this metallicity one usually sees strontium and barium
abundance ratios that are roughly equal. Possible formation scenarios of this
peculiar object are considered.Comment: 13 pages, 3 figures. Accepted to ApJ
The Evolution of Early-type Field Galaxies Selected from a NICMOS Map of the Hubble Deep Field North
The redshift distribution of well-defined samples of distant early-type
galaxies offers a means to test the predictions of monolithic and hierarchical
galaxy formation scenarios. NICMOS maps of the entire Hubble Deep Field North
in the F110W and F160W filters, when combined with the available WFPC2 data,
allow us to calculate photometric redshifts and determine the morphological
appearance of galaxies at rest-frame optical wavelengths out to z ~ 2.5. Here
we report results for two subsamples of early-type galaxies, defined primarily
by their morphologies in the F160W band, which were selected from the NICMOS
data down to H160_{AB} < 24.0. The observed redshift distributions of our two
early-type samples do not match that predicted by a monolithic collapse model,
which shows an overabundance at z > 1.5. A hierarchical formation model better
matches the redshift distribution of the HDF-N early-types at z > 1.5, but
still does not adequately describe the observed early-types. The hierarchical
model predicts significantly bluer colors on average than the observed
early-type colors, and underpredicts the observed number of early-types at z <
1. [abridged]Comment: Accepted for publication in the Astronomical Journal; 54 pages, 21
figures. Figures 10 and 11 are included separately in JPEG forma
Constructing a WISE High Resolution Galaxy Atlas
After eight months of continuous observations, the Wide-field Infrared Survey
Explorer (WISE) mapped the entire sky at 3.4 {\mu}m, 4.6 {\mu}m, 12 {\mu}m and
22 {\mu}m. We have begun a dedicated WISE High Resolution Galaxy Atlas (WHRGA)
project to fully characterize large, nearby galaxies and produce a legacy image
atlas and source catalogue. Here we summarize the deconvolution technique used
to significantly improve the spatial resolution of WISE imaging, specifically
designed to study the internal anatomy of nearby galaxies. As a case study, we
present results for the galaxy NGC 1566, comparing the WISE super-resolution
image processing to that of Spitzer, GALEX and ground-based imaging. The is the
first paper in a two part series; results for a much larger sample of nearby
galaxies is presented in the second paper.Comment: Published in the AJ (2012, AJ, 144, 68
Scaling Relations and Overabundance of Massive Clusters at z>~1 from Weak-Lensing Studies with HST
We present weak gravitational lensing analysis of 22 high-redshift (z >~1)
clusters based on Hubble Space Telescope images. Most clusters in our sample
provide significant lensing signals and are well detected in their
reconstructed two-dimensional mass maps. Combining the current results and our
previous weak-lensing studies of five other high-z clusters, we compare
gravitational lensing masses of these clusters with other observables. We
revisit the question whether the presence of the most massive clusters in our
sample is in tension with the current LambdaCDM structure formation paradigm.
We find that the lensing masses are tightly correlated with the gas
temperatures and establish, for the first time, the lensing mass-temperature
relation at z >~ 1. For the power law slope of the M-TX relation (M propto
T^{\alpha}), we obtain \alpha=1.54 +/- 0.23. This is consistent with the
theoretical self-similar prediction \alpha=3/2 and with the results previously
reported in the literature for much lower redshift samples. However, our
normalization is lower than the previous results by 20-30%, indicating that the
normalization in the M-TX relation might evolve. After correcting for Eddington
bias and updating the discovery area with a more conservative choice, we find
that the existence of the most massive clusters in our sample still provides a
tension with the current Lambda CDM model. The combined probability of finding
the four most massive clusters in this sample after marginalization over
current cosmological parameters is less than 1%.Comment: ApJ in press. See http://www.supernova.lbl.gov for additional
information pertaining to the HST Cluster SN Surve
The Cluster and Field Galaxy Active Galactic Nucleus Fraction at Z = 1-1.5: Evidence for a Reversal of the Local Anticorrelation between Environment and AGN Fraction
The fraction of cluster galaxies that host luminous active galactic nuclei (AGNs) is an important probe of AGN fueling processes, the cold interstellar medium at the centers of galaxies, and how tightly black holes and galaxies co-evolve. We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies (M \u3e= 1014 M ⊙) at 1 \u3c z \u3c 1.5 selected from the Spitzer/IRAC Shallow Cluster Survey, as well as the field fraction in the immediate vicinity of these clusters, and combine these data with measurements from the literature to quantify the relative evolution of cluster and field AGN from the present to z ~ 3. We estimate that the cluster AGN fraction at 1 \u3c z \u3c 1.5 is f_A = 3.0^{+2.4}_{-1.4}% for AGNs with a rest-frame, hard X-ray luminosity greater than L X, H \u3e= 1044 erg s-1. This fraction is measured relative to all cluster galaxies more luminous than M^*_{3.6}(z) + 1, where M^*_{3.6}(z) is the absolute magnitude of the break in the galaxy luminosity function at the cluster redshift in the IRAC 3.6 μm bandpass. The cluster AGN fraction is 30 times greater than the 3σ upper limit on the value for AGNs of similar luminosity at z ~ 0.25, as well as more than an order of magnitude greater than the AGN fraction at z ~ 0.75. AGNs with L X, H \u3e= 1043 erg s-1 exhibit similarly pronounced evolution with redshift. In contrast to the local universe, where the luminous AGN fraction is higher in the field than in clusters, the X-ray and MIR-selected AGN fractions in the field and clusters are consistent at 1 \u3c z \u3c 1.5. This is evidence that the cluster AGN population has evolved more rapidly than the field population from z ~ 1.5 to the present. This environment-dependent AGN evolution mimics the more rapid evolution of star-forming galaxies in clusters relative to the field
The WIRCAM Deep Infrared Cluster Survey I: Groups and Clusters at z > 1.1
We use CFHTLS deep optical data, WIRCam Deep Survey (WIRDS) NIR data and XMM
data to identify z>1.1 clusters in the CFHTLS D1 and D4 fields. Counterparts to
such clusters can not be identified without deep NIR data and as such the total
of =1deg2 of J , H & Ks band imaging provided by WIRDS is an indispensable tool
in such work. Using public XMM X-ray data, we identify extended X-ray sources
in the two fields. The resulting catalogue of extended X-ray sources was
analyzed for optical/NIR counterparts, using a red-sequence algorithm.
Redshifts of candidate groups and clusters were estimated using the median
photometric redshifts of detected counterparts and where available
spectroscopic data. Additionally, we surveyed X-ray point sources for potential
group systems at the limit of our detection range in the X-ray data. A
catalogue of z > 1.1 cluster candidates in the two fields has been compiled and
cluster masses, radii and temperatures have been estimated using the scaling
relations. The catalogue consists of 15 z > 1.1 candidates. Three of the
detections are previously published extended X-ray sources. Of note is JKSC 041
for which we identify possible structures at z = 0.8, z = 0.96, z = 1.13 and z
= 1.49. We also make an independent detection of the massive cluster, XMMXCS
J2215.9-1738. We use the z > 1.1 catalogue to compare the cluster number counts
in these fields with models based on WMAP 7-year cosmology and find that the
models slightly over-predict the observations, whilst at z>1.5 we do not detect
any clusters. We note that cluster number counts at z > 1.1 are highly
sensitive to the cosmological model, however a significant reduction in present
statistical (due to available survey area) and systematic (due to cluster
scaling relations) uncertainties is required in order to confidently constrain
cosmological parameters using cluster number counts at high redshift.Comment: 22 pages, 22 figures, Accepted 4 August 201
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