361 research outputs found
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MASCOT: an ESO-ARO legacy survey of molecular gas in nearby SDSS-MaNGA galaxies - I. First data release, and global and resolved relations between H<inf>2</inf>and stellar content
We present the first data release of the MaNGA-ARO Survey of CO Targets
(MASCOT), an ESO Public Spectroscopic Survey conducted at the Arizona Radio
Observatory (ARO). We measure the CO(1-0) line emission in a sample of 187
nearby galaxies selected from the Mapping Nearby Galaxies at Apache Point
Observatory (MaNGA) survey that has obtained integral field unit (IFU)
spectroscopy for a sample of ~ 10,000 galaxies at low redshift. The main goal
of MASCOT is to probe the molecular gas content of star-forming galaxies with
stellar masses > 10^9.5 M_solar and with associated MaNGA IFU observations and
well-constrained quantities like stellar masses, star formation rates and
metallicities. In this paper we present the first results of the MASCOT survey,
providing integrated CO(1-0) measurements that cover several effective radii of
the galaxy and present CO luminosities, CO kinematics, and estimated H2 gas
masses. We observe that the decline of galaxy star formation rate with respect
to the star formation main sequence (SFMS) increases with the decrease of
molecular gas and with a reduced star formation efficiency, in agreement with
results of other integrated studies. Relating the molecular gas mass fractions
with the slope of the stellar age gradients inferred from the MaNGA
observations, we find that galaxies with lower molecular gas mass fractions
tend to show older stellar populations close to the galactic center, while the
opposite is true for galaxies with higher molecular gas mass fractions,
providing tentative evidence for inside-out quenching
The completed SDSS-IV extended baryon oscillation spectroscopic survey: Geometry and growth from the anisotropic void-galaxy correlation function in the luminous red galaxy sample
We present an analysis of the anisotropic redshift-space void-galaxy correlation in configuration space using the Sloan Digital Sky Survey extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 16 luminous red galaxy (LRG) sample. This sample consists of LRGs between redshifts 0.6 and 1.0, combined with the high redshift z > 0.6 tail of the Baryon Oscillation Spectroscopic Survey Data Release 12 CMASS sample. We use a reconstruction method to undo redshift-space distortion (RSD) effects from the galaxy field before applying a watershed void-finding algorithm to remove bias from the void selection. We then perform a joint fit to the multipole moments of the correlation function for the growth rate fσ 8 and the geometrical distance ratio DM/DH, finding f σ8 (zeff ) = 0.356 ± 0.079 and DM /DH (zeff ) = 0.868 ± 0.017 at the effective redshift zeff = 0.69 of the sample. The posterior parameter degeneracies are orthogonal to those from galaxy clustering analyses applied to the same data, and the constraint achieved on DM/DH is significantly tighter. In combination with the consensus galaxy BAO and full-shape analyses of the same sample, we obtain fσ 8 = 0.447 ± 0.039, DM/rd = 17.48 ± 0.23, and DH/rd = 20.10 ± 0.34. These values are in good agreement with the ΛCDM model predictions and represent reductions in the uncertainties of 13 per cent, 23 per cent, and 28 per cent, respectively, compared to the combined results from galaxy clustering, or an overall reduction of 55 per cent in the allowed volume of parameter space
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REDSHIFT MEASUREMENT and SPECTRAL CLASSIFICATION for eBOSS GALAXIES with the REDMONSTER SOFTWARE
We describe the redmonster automated redshift measurement and spectral classification software designed for the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). We describe the algorithms, the template standard and requirements, and the newly developed galaxy templates to be used on eBOSS spectra. We present results from testing on early data from eBOSS, where we have found a 90.5% automated redshift and spectral classification success rate for the luminous red galaxy sample (redshifts 0.6 ≲ z ≲ 1.0). The redmonster performance meets the eBOSS cosmology requirements for redshift classification and catastrophic failures and represents a significant improvement over the previous pipeline. We describe the empirical processes used to determine the optimum number of additive polynomial terms in our models and an acceptable δX2rthreshold for declaring statistical confidence. Statistical errors on redshift measurement due to photon shot noise are assessed, and we find typical values of a few tens of km s-1. An investigation of redshift differences in repeat observations scaled by error estimates yields a distribution with a Gaussian mean and standard deviation of μ ∼ 0.01 and σ ∼ 0.65, respectively, suggesting the reported statistical redshift uncertainties are over-estimated by ∼54%. We assess the effects of object magnitude, signal-to-noise ratio, fiber number, and fiber head location on the pipeline's redshift success rate. Finally, we describe directions of ongoing development
Running Gauge Coupling in Asymptotically Safe Quantum Gravity
We investigate the non-perturbative renormalization group behavior of the
gauge coupling constant using a truncated form of the functional flow equation
for the effective average action of the Yang-Mills-gravity system. We find a
non-zero quantum gravity correction to the standard Yang-Mills beta function
which has the same sign as the gauge boson contribution. Our results fit into
the picture according to which Quantum Einstein Gravity (QEG) is asymptotically
safe, with a vanishing gauge coupling constant at the non-trivial fixed point.Comment: 27 page
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SDSS IV MaNGA-spatially resolved diagnostic diagrams: A proof that many galaxies are LIERs
We study the spatially resolved excitation properties of the ionised gas in a
sample of 646 galaxies using integral field spectroscopy data from SDSS-IV
MaNGA. Making use of Baldwin-Philips-Terlevich diagnostic diagrams we
demonstrate the ubiquitous presence of extended (kpc scale) low ionisation
emission-line regions (LIERs) in both star forming and quiescent galaxies. In
star forming galaxies LIER emission can be associated with diffuse ionised gas,
most evident as extra-planar emission in edge-on systems. In addition, we
identify two main classes of galaxies displaying LIER emission: `central LIER'
(cLIER) galaxies, where central LIER emission is spatially extended, but
accompanied by star formation at larger galactocentric distances, and `extended
LIER' (eLIER) galaxies, where LIER emission is extended throughout the whole
galaxy. In eLIER and cLIER galaxies, LIER emission is associated with radially
flat, low H equivalent width of line emission ( 3 \AA) and stellar
population indices demonstrating the lack of young stellar populations,
implying that line emission follows tightly the continuum due to the underlying
old stellar population. The H surface brightness radial profiles are
always shallower than and the line ratio
[OIII]5007/[OII]3727,29 (a tracer of the ionisation parameter
of the gas) shows a flat gradient. This combined evidence strongly supports the
scenario in which LIER emission is not due to a central point source but to
diffuse stellar sources, the most likely candidates being hot, evolved
(post-asymptotic giant branch) stars. Shocks are observed to play a significant
role in the ionisation of the gas only in rare merging and interacting systems.STFCThis is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Oxford University Press
SDSS-IV MaNGA: A serendipitous observation of a potential gas accretion event
The nature of warm, ionized gas outside of galaxies may illuminate several key galaxy evolutionary processes. A serendipitous observation by the MaNGA survey has revealed a large, asymmetric H complex with no optical counterpart that extends ≈8″ (≈6.3 kpc) beyond the effective radius of a dusty, starbursting galaxy. This H extension is approximately three times the effective radius of the host galaxy and displays a tail-like morphology. We analyze its gas-phase metallicities, gaseous kinematics, and emission-line ratios and discuss whether this H extension could be diffuse ionized gas, a gas accretion event, or something else. We find that this warm, ionized gas structure is most consistent with gas accretion through recycled wind material, which could be an important process that regulates the low-mass end of the galaxy stellar mass function.Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration. D.B. is supported by grant RSCF-14-22-00041. A.W. acknowledges support from a Leverhulme Early Career Fellowship. J.H.K. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under grant number AYA2013-41243-P and thanks the Astrophysics Research Institute of Liverpool John Moores University for their hospitality, and the Spanish Ministry of Education, Culture and Sports for financial support of his visit there, through grant number PR2015-00512
Controlling Pandemic Flu: The Value of International Air Travel Restrictions
BACKGROUND: Planning for a possible influenza pandemic is an extremely high priority, as social and economic effects of an unmitigated pandemic would be devastating. Mathematical models can be used to explore different scenarios and provide insight into potential costs, benefits, and effectiveness of prevention and control strategies under consideration. METHODS AND FINDINGS: A stochastic, equation-based epidemic model is used to study global transmission of pandemic flu, including the effects of travel restrictions and vaccination. Economic costs of intervention are also considered. The distribution of First Passage Times (FPT) to the United States and the numbers of infected persons in metropolitan areas worldwide are studied assuming various times and locations of the initial outbreak. International air travel restrictions alone provide a small delay in FPT to the U.S. When other containment measures are applied at the source in conjunction with travel restrictions, delays could be much longer. If in addition, control measures are instituted worldwide, there is a significant reduction in cases worldwide and specifically in the U.S. However, if travel restrictions are not combined with other measures, local epidemic severity may increase, because restriction-induced delays can push local outbreaks into high epidemic season. The per annum cost to the U.S. economy of international and major domestic air passenger travel restrictions is minimal: on the order of 0.8% of Gross National Product. CONCLUSIONS: International air travel restrictions may provide a small but important delay in the spread of a pandemic, especially if other disease control measures are implemented during the afforded time. However, if other measures are not instituted, delays may worsen regional epidemics by pushing the outbreak into high epidemic season. This important interaction between policy and seasonality is only evident with a global-scale model. Since the benefit of travel restrictions can be substantial while their costs are minimal, dismissal of travel restrictions as an aid in dealing with a global pandemic seems premature
Swine-Origin Influenza A Outbreak 2009 at Shinshu University, Japan
<p>Abstract</p> <p>Background</p> <p>A worldwide outbreak of swine flu H1N1 pandemic influenza occurred in April 2009. To determine the mechanism underlying the spread of infection, we prospectively evaluated a survey implemented at a local university.</p> <p>Methods</p> <p>Between August 2009 and March 2010, we surveyed 3 groups of subjects: 2318 children in six schools attached to the Faculty of Education, 11424 university students, and 3344 staff members. Subjects with influenza-like symptoms who were diagnosed with swine flu at hospitals or clinics were defined as swine flu patients and asked to make a report using a standardized form.</p> <p>Results</p> <p>After the start of the pandemic, a total of 2002 patients (11.7%) were registered in the survey. These patients included 928 schoolchildren (40.0%), 1016 university students (8.9%), and 58 staff members (1.7%). The incidence in schoolchildren was significantly higher than in the other 2 groups (<it>P </it>< 0.0001) but there were no within group differences in incidence rate between males and females. During the period of the survey, three peaks of patient numbers were observed, in November 2009, December 2009, and January 2010. The first peak consisted mainly of schoolchildren, whereas the second and third peaks included many university students. Staff members did not contribute to peak formation. Among the university students, the most common suspected route of transmission was club activity. Interventions, such as closing classes, schools, and clubs, are likely to affect the epidemic curves.</p> <p>Conclusion</p> <p>Schoolchildren and university students are vulnerable to swine flu, suggesting that avoidance of close contact, especially among these young people, may be effective way in controlling future severe influenza pandemics, especially at educational institutions.</p
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