We report the first detection obtained with ALMA of the N II 122\(\mu\)m line emission from a galaxy group BRI 1202-0725 at \(z=4.69\) consisting of a QSO and a submilimeter-bright galaxy (SMG). ...Combining with a detection of N II 205\(\mu\)m line in both galaxies, we constrain the electron densities of the ionized gas based on the line ratio of NII122/205. The derived electron densities are \(26^{+12}_{-11}\) and \(134^{+50}_{-39}\) cm\(^{-3}\) for the SMG and the QSO, respectively. The electron density of the SMG is similar to that of the Galactic Plane and to the average of the local spirals. Higher electron densities by up to a factor of three could, however, be possible for systematic uncertainties of the line flux estimates. The electron density of the QSO is comparable to high-\(z\) star-forming galaxies at \(z=1.5-2.3\), obtained using rest-frame optical lines and with the lower limits suggested from stacking analysis on lensed starbursts at \(z=1-3.6\) using the same tracer of NII. Our results suggest a large scatter of electron densities in global scale at fixed star formation rates for extreme starbursts. The success of the N II 122\(\mu\)m and 205\(\mu\)m detections at \(z=4.69\) demonstrates the power of future systematic surveys of extreme starbursts at \(z>4\) for probing the ISM conditions and the effects on surrounding environments.
We present a theoretical investigation of the light, radius and radial velocity variations of the prototype \(\delta\) Cephei. We find that the best fit model accounts for luminosity and velocity ...amplitudes with an accuracy better than \(0.8\sigma\), and for the radius amplitude with an accuracy of \(1.7\sigma\). The chemical composition of this model suggests a decrease in both helium (0.26 vs 0.28) and metal (0.01 vs 0.02) content in the solar neighborhood. Moreover, distance determinations based on the fit of light curves agree at the \(0.8\sigma\) level with the trigonometric parallax measured by the Hubble Space Telescope (HST). On the other hand, distance determinations based on angular diameter variations, that are independent of interstellar extinction and of the \(p\)-factor value, indicate an increase of the order of 5% in the HST parallax.
The globular cluster \(\omega\) Centauri (NGC 5139) is a puzzling stellar system harboring several distinct stellar populations whose origin still represents a unique astrophysical challenge. Current ...scenarios range from primordial chemical inhomogeneities in the mother cloud to merging of different sub-units and/or subsequent generations of enriched stars - with a variety of different pollution sources- within the same potential well. In this paper we study the chemical abundance pattern in the outskirts of Omega Centauri, half-way to the tidal radius (covering the range of 20-30 arcmin from the cluster center), and compare it with chemical trends in the inner cluster regions, in an attempt to explore whether the same population mix and chemical compositions trends routinely found in the more central regions is also present in the cluster periphery.We extract abundances of many elements from FLAMES/UVES spectra of 48 RGB stars using the equivalent width method and then analyze the metallicity distribution function and abundance ratios of the observed stars. We find, within the uncertainties of small number statistics and slightly different evolutionary phases, that the population mix in the outer regions cannot be distinguished from the more central regions, although it is clear that more data are necessary to obtain a firmer description of the situation. From the abundance analysis, we did not find obvious radial gradients in any of the measured elements.
The stellar metallicity is a direct measure of the amount of metals present in a galaxy, as a large part of the metals lie in its stars. In this paper we investigate new stellar metallicity ...indicators suitable for high-z galaxies studying the stellar photospheric absorption lines in the rest frame ultraviolet, hence sampling predominantly young hot stars. We defined these new indicators based on the equivalent widths (EW) of selected features using theoretical spectra created with the evolutionary population synthesis code Starburts99. We used them to compute the stellar metallicity for a sample of UV-selected galaxies at z > 3 from the AMAZE survey using very deep (37h per object) VLT/FORS spectra. Moreover, we applied the new metallicity indicators to eight additional high redshift galaxies found in literature. We then compared stellar and gas-phase metallicities measured from the emission lines for all these galaxies, finding that within the errors the two estimates are in good agreement, with possible tendency to have stellar metallicities lower than the gas phase ones. For the first time, we are able to study the stellar mass-metallicity relation at z > 3. We find that the metallicity of young, hot stars in galaxies at z \sim 3 have similar values of the aged stars in local SDSS galaxies, contrary to what observed for the gas phase metallicity.
We study the metallicity properties of galaxies in the zCOSMOS sample between 0.2<z<0.8. At z<0.46, where Ha and NII are detected, we find the same dependence of metallicity on stellar mass and Star ...Formation Rate (SFR), the Fundamental Metallicity Relation, found by Mannucci et al. (2010) in SDSS galaxies on a similar redshift range. We extend this relation to higher redshift, 0.49<z<0.8 where the R23 metallicity index can be measured in our data, finding no evidence for evolution, and a metallicity scatter around the relation of about 0.16 dex. This result confirms, with a much higher level of significance with respect to previous works, the absence of evolution of the FMR during the last half of cosmic history.
The association between exposure to urban air pollution and cardiac or respiratory impairments in susceptible subjects was evaluated in a panel study including 11 patients with chronic obstructive ...pulmonary disease (COPD), 7 with ischemic heart disease (IHD), and 11 asthmatics resident in Rome (Italy). Patients underwent repeated 24 h Holter EKG monitoring, 12 h pulse oximetry at night and spirometry examinations during 1999 summer and winter. Multiple linear regression models for repeated individual measures (fixed-effect) were used to analyse the relationship between average daily concentrations of pollutants (PM10-2.5, PM2.5 NO2 and O3) and outcome variables, controlling for meteorological conditions, survey period, and week-ends. In the BPCO panel, increasing ambient PM2.5 levels were associated with increased heart rate and decreased respiratory function. In the asthmatic panel, inverse associations between pulmonary function and both NO2 and PM10-2.5 concentrations were observed, as well as direct association between ambient NO2 concentrations and NO in exhaled breath. In the IHD panel an increase of hearth rate variability associated with increasing concentration of PM2.5 was observed.
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We report on the results from an ongoing program aimed at testing Newton's law of gravity in the low acceleration regime using globular clusters. It is shown that all clusters studied so far do ...behave like galaxies, that is, their velocity dispersion profile flattens out at large radii where the acceleration of gravity goes below 1e-8 cm/s/s, instead of following the expected Keplerian fall off. In galaxies this behavior is ascribed to the existence of a dark matter halo. Globular clusters, however, do not contain dark matter, hence this result might indicate that our present understanding of gravity in the weak regime of accelerations is incomplete and somehow incorrect.
A test of Newton's law of gravity in the low acceleration regime using
globular clusters is presented. New results for the core collapsed globular
cluster NGC 7099 are given. The run of the ...gravitational potential as a
function of distance is probed studying the velocity dispersion profile of the
cluster, as derived from a set of 125 radial velocities with accuracy better
than 1 km/s. The velocity dispersion profile is traced up to ~18 pc from the
cluster center. The dispersion is found to be maximal at the center, then
decrease until 10+-2 pc from the center, well inside the cluster tidal radius
of 42 pc. After that the dispersion remains constant with average value
2.2+-0.3 km/s. Assuming for NGC 7099 a total V mag of M(V)=-7.43 mags and
mass-to-light ratio M/L=1, the acceleration at 10 pc from the center is 1.1e-8
cm/s/s. Thus, the flattening of the velocity dispersion profile occurs for a
value of the internal acceleration of gravity fully consistent with a_0=1.2e-8
cm/s/s observed in galaxies. This new result for NGC 7099 brings to 4 the
clusters with velocity dispersion profile probing acceleration below a_0. All
four have been found to have a flat dispersion profile at large radii where the
acceleration is below a_0, mimicking qualitatively and quantitatively
elliptical galaxies. Whether this indicates a failure of Newtonian dynamics in
the low acceleration limit or some more conventional dynamical effect (e.g.,
tidal heating) is still unclear. However, the similarities emerging between
very different globular clusters, as well as between globular clusters and
elliptical galaxies seem to favor the first of these two possibilities.
