2,088 research outputs found
Extending the M_(bh)-sigma diagram with dense nuclear star clusters
Abridged: Four new nuclear star cluster masses, M_nc, plus seven upper
limits, are provided for galaxies with previously determined black hole masses,
M_bh. Together with a sample of 64 galaxies with direct M_bh measurements, 13
of which additionally now have M_nc measurements rather than only upper limits,
plus an additional 29 dwarf galaxies with available M_nc measurements and
velocity dispersions sigma, an (M_bh + M_nc)-sigma diagram is constructed.
Given that major dry galaxy merger events preserve the M_bh/L ratio, and given
that L ~ sigma^5 for luminous galaxies, it is first noted that the observation
M_bh ~ sigma^5 is consistent with expectations. For the fainter elliptical
galaxies it is known that L ~ sigma^2, and assuming a constant M_nc/L ratio
(Ferrarese et al.), the expectation that M_nc ~ sigma^2 is in broad agreement
with our new observational result that M_nc ~ sigma^{1.57\pm0.24}. This
exponent is however in contrast to the value of ~4 which has been reported
previously and interpreted in terms of a regulating feedback mechanism from
stellar winds.Comment: 6 pages, 2 figures. Submitted 08/08/2011 to MNRAS, first referee
report received 19/01/2012, accepted 10/02/201
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San Andres/Grayburg Reservoir Characterization Research Laboratory
The Bureau of Economic Geology's Reservoir Characterization Research Laboratory project, "Characterization of San Andres and Grayburg Reservoirs," was initiated in September 1988 and has completed the first year of a proposed 2-year program. Substantial progress has been made toward the goals of this program, which are focused on development of advanced approaches to reservoir characterization for improving recovery efficiency of substantial remaining mobile oil resources in these prolific reservoirs. Key research results are in the areas of (1) quantitative description and geostatistical modeling of interwell and reservoir-scale heterogeneity from San Andres outcrops, and (2) preliminary studies on integration of the quantitative outcrop models with a geologic/engineering characterization of the Seminole San Andres Unit.
Outcrop geologic studies were carried out at play, reservoir, and interwell scales along the Algerita Escarpment, Guadalupe Mountains, New Mexico. This 17-mile play-scale study area provides a dip-section framework for detailed investigations and serves as an analogous reservoir framework for comparison with producing San Andres fields. Reservoir-scale mapping of a 4-mile dip section of the upper San Andres with measured sections spaced 1,000 to 2,000 ft apart demonstrates the compartmentalization of individual grainstone shoal complexes on the scale of several thousand feet laterally and 50 to 100 ft vertically.Bureau of Economic Geolog
The atypical chemokine receptor-2 does not alter corneal graft survival but regulates early stage of corneal graft induced lymphangiogenesis
Open Access via Springer Compact Agreement Funding: Saving Sight in Grampian provided financial support in the forming of Saving Sight in Grampian funding. The sponsor had no role in the design or conduct of this research.Peer reviewedPublisher PD
A Search for the Most Massive Galaxies. III. Global and Central Structure
We used the Advanced Camera for Surveys on board the Hubble Space Telescope
to obtain high resolution i-band images of the centers of 23 single galaxies,
which were selected because they have SDSS velocity dispersions larger than 350
km/s. The surface brightness profiles of the most luminous of these objects
(M_i<-24) have well-resolved `cores' on scales of 150-1000 pc, and share
similar properties to BCGs. The total luminosity of the galaxy is a better
predictor of the core size than is the velocity dispersion. The correlations of
luminosity and velocity dispersion with core size agree with those seen in
previous studies of galaxy cores. Because of high velocity dispersions, our
sample of galaxies can be expected to harbor the most massive black holes, and
thus have large cores with large amounts of mass ejection. The mass-deficits
inferred from core-Sersic fits to the surface-brightness profiles are
approximately double the black-hole masses inferred from the M_bh-sigma
relation and the same as those inferred from the M_bh-L relation. The less
luminous galaxies (M_i>-23) tend to have steeper `power-law' inner profiles,
higher-ellipticity, diskier isophotes, and bulge-to-total ratios of order 0.5
-- all of which suggest that they are `fast-rotators' and rotational motions
could have contaminated the velocity dispersion estimate. There are obvious
dust features within about 300 pc of the center in about 35% of the sample,
predominantly in power-law rather than core galaxies.Comment: 27 Pages, 22 Figures, 2 Tables, Accepted for Publication in MNRA
The Red Sequence Luminosity Function in Massive Intermediate Redshift Galaxy Clusters
We measure the rest-frame B-band luminosity function of red-sequence galaxies
(RSLF) of five intermediate-redshift (0.5 950
km/s) clusters. Cluster galaxies are identified through photometric redshifts
based on imaging in seven bands (five broad, and two narrow) using the WIYN
3.5m telescope. The luminosity functions are well-fit down to M_B^*+3 for all
of the clusters out to a radius of R_200. For comparison, the luminosity
functions for a sample of 59 low redshift clusters selected from the SDSS are
measured as well. There is a brightening trend (M_B^* increases by 0.7 mags by
z=0.75) with redshift comparable to what is seen in the field for similarly
defined galaxies, although there is a hint that the cluster red-sequence
brightening is more rapid in the past (z>0.5), and relatively shallow at more
recent times. Contrary to other claims, we find little evidence for evolution
of the faint end slope. Previous indications of evolution may be due to
limitations in measurement technique, bias in the sample selection, and cluster
to cluster variation. As seen in both the low and high redshift sample, a
significant amount of variation in luminosity functions parameters alpha and
M^* exists between individual clusters.Comment: 40 pages, 14 figures, accepted for publication in the Astrophysical
Journa
The Non-structural Protein 5 and Matrix Protein Are Antigenic Targets of T Cell Immunity to Genotype 1 Porcine Reproductive and Respiratory Syndrome Viruses
The porcine reproductive and respiratory syndrome virus (PRRSV) is the cause of one of the most economically important diseases affecting swine worldwide. Efforts to develop a next-generation vaccine have largely focussed on envelope glycoproteins to target virus-neutralising antibody responses. However, these approaches have failed to demonstrate the necessary efficacy to progress towards market. T cells are crucial to the control of many viruses through cytolysis and cytokine secretion. Since control of PRRSV infection is not dependent on the development of neutralising antibodies, it has been proposed that T cell mediated immunity plays a key role. We therefore hypothesised that conserved T cell antigens represent prime candidates for the development a novel PRRS vaccine. Antigens were identified by screening a proteome-wide synthetic peptide library with T cells from cohorts of pigs rendered immune by experimental infections with a closely-related (subtype 1) or divergent (subtype 3) PRRSV-1 strain. Dominant T cell IFN-γ responses were directed against the non-structural protein 5 (NSP5), and to a lesser extent, the matrix (M) protein. The majority of NSP5-specific CD8 T cells and M-specific CD4 T cells expressed a putative effector memory phenotype and were polyfunctional as assessed by co-expression of TNF-α and mobilisation of the cytotoxic degranulation marker CD107a. Both antigens were generally well conserved amongst strains of both PRRSV genotypes. Thus M and NSP5 represent attractive vaccine candidate T cell antigens which should be evaluated further in the context of PRRSV vaccine development
The bright galaxy population of five medium redshift clusters. II. Quantitative Galaxy Morphology
Aims: Following the study already presented in our previous paper, based on
the Nordic Optical Telescope (NOT) sample, which consists of five clusters of
galaxies within the redshift range 0.18 z 0.25, imaged in the
central 0.5-2 Mpc in very good seeing conditions, we have studied the
quantitative morphology of their bright galaxy population
Methods: We have analyzed the surface brightness profiles of the galaxy
population in those clusters. Previously, we have performed simulations in
order to check the reliability of the fits. We have also derived a quantitative
morphological classification.
Results: The structural parameters derived from these analysis have been
analyzed. We have obtained that the structural parameters of E/S0 galaxies are
similar to those showed by galaxies in low redshift clusters. However, the disc
scales are different. In particular, the scales of the discs of galaxies at
medium redshift clusters are statistically different than those located in
similar galaxies in the Coma cluster. But, the scales of the discs of galaxies
in medium redshift clusters are similar to nearby field galaxies.
Conclusions: The results suggest that the evolution of the disc component of
galaxies in clusters is faster than in field ones. Mechanisms like galaxy
harassment showing timescales of Gyr could be the responsible of this
disc scale evolution. This indicates that spiral galaxies in clusters have
suffered a strong evolution in the last 2.5 Gyr or that Coma is in some way
anomalous.Comment: 13 pages, 10 figures, Accepted for publication in A&
Evolution of the Red Sequence Giant to Dwarf Ratio in Galaxy Clusters out to z ~ 0.5
We analyze deep g' and r' band data of 97 galaxy clusters imaged with MegaCam
on the Canada-France-Hawaii telescope. We compute the number of luminous
(giant) and faint (dwarf) galaxies using criteria based on the definitions of
de Lucia et al. (2007). Due to excellent image quality and uniformity of the
data and analysis, we probe the giant-to-dwarf ratio (GDR) out to z ~ 0.55.
With X-ray temperature (Tx) information for the majority of our clusters, we
constrain, for the first time, the Tx-corrected giant and dwarf evolution
separately. Our measurements support an evolving GDR over the redshift range
0.05 < z < 0.55. We show that modifying the (g'-r'), m_r' and K-correction used
to define dwarf and giant selection do not alter the conclusion regarding the
presence of evolution. We parameterize the GDR evolution using a linear
function of redshift (GDR = alpha * z + beta) with a best fit slope of alpha =
0.88 +/- 0.15 and normalization beta = 0.44 +/- 0.03. Contrary to claims of a
large intrinsic scatter, we find that the GDR data can be fully accounted for
using observational errors alone. Consistently, we find no evidence for a
correlation between GDR and cluster mass (via Tx or weak lensing). Lastly, the
data suggest that the evolution of the GDR at z < 0.2 is driven primarily by
dry merging of the massive giant galaxies, which when considered with previous
results at higher redshift, suggests a change in the dominant mechanism that
mediates the GDR.Comment: 20 pages, 15 figures. Accepted to MNRA
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