Using the Atacama Large Millimeter/sub-millimeter Array, we have detected CO(3-2) line and far-infrared continuum emission from a galaxy associated with a high-metallicity (M/H = -0.27) damped ...Ly-alpha absorber (DLA) at z =2.19289. The galaxy is located 3.5" away from the quasar sightline, corresponding to a large impact parameter of 30 kpc at the DLA redshift. We use archival Very Large Telescope-SINFONI data to detect Halpha emission from the associated galaxy, and find that the object is dusty, with a dust-corrected star formation rate of 110 +60 -30 Msun/yr. The galaxy's molecular mass is large, Mmol = (1.4 +- 0.2) x 10^11 x (\alpha_CO/4.3) x (0.57/r_31) Msun, supporting the hypothesis that high-metallicity DLAs arise predominantly near massive galaxies. The excellent agreement in redshift between the CO(3-2) line emission and low-ion metal absorption (~40 km/s) disfavors scenarios whereby the gas probed by the DLA shows bulk motion around the galaxy. We use Giant Metrewave Radio Telescope HI 21cm absorption spectroscopy to find that the HI along the DLA sightline must be warm, with a stringent lower limit on the spin temperature of T_s > 1895 x (f/0.93) K. The detection of CI absorption in the DLA, however, also indicates the presence of cold neutral gas. To reconcile these results requires that the cold components in the DLA contribute little to the HI column density, yet contain roughly 50% of the metals of the absorber, underlining the complex multi-phase nature of the gas surrounding high-z galaxies.
We present the detection analysis of a diffuse molecular cloud at z\(_{abs}\)=2.4636 towards the quasar SDSS J1513+0352(z\(_{em}\,\simeq\) 2.68) observed with the X-shooter spectrograph(VLT). We ...measure very high column densities of atomic and molecular hydrogen, with log N(HI,H\(_2\))\(\simeq\)21.8,21.3. This is the highest H\(_2\) column density ever measured in an intervening damped Lyman-alpha system but we do not detect CO, implying log N(CO)/N(H\(_2\)) < -7.8, which could be due to a low metallicity of the cloud. From the metal absorption lines, we derive the metallicity to be Z \(\simeq\) 0.15 Z\(_{\odot}\) and determine the amount of dust by measuring the induced extinction of the background quasar light, A\(_V\) \(\simeq\) 0.4. We also detect Ly-\(\alpha\) emission at the same redshift, with a centroid located at a most probable impact parameter of only \(\rho\,\simeq\) 1.4 kpc. We argue that the line of sight is therefore likely passing through the ISM of a galaxy as opposed to the CGM. The relation between the surface density of gas and that of star formation seems to follow the global empirical relation derived in the nearby Universe although our constraints on the star formation rate and on the galaxy extent remain too loose to be conclusive. We study the transition from atomic to molecular hydrogen using a theoretical description based on the microphysics of molecular hydrogen. We use the derived chemical properties of the cloud and physical conditions (T\(_k\,\simeq\)90 K and n\(\simeq\)250 cm\(^{-3}\) derived through the excitation of H\(_2\) rotational levels and neutral carbon fine structure transitions to constrain the fundamental parameters that govern this transition. By comparing the theoretical and observed HI column densities, we are able to bring an independent constraint on the incident UV flux, which we find to be in agreement with that estimated from the observed star formation rate.
We present the discovery and optical follow-up of the faintest supernova-like transient known. The event (SN 2019gsc) was discovered in a star-forming host at 53\,Mpc by ATLAS. A detailed ...multi-colour light curve was gathered with Pan-STARRS1 and follow-up spectroscopy was obtained with the NOT and Gemini-North. The spectra near maximum light show narrow features at low velocities of 3000 to 4000 km s\(^{-1}\), similar to the extremely low luminosity SNe 2010ae and 2008ha, and the light curve displays a similar fast decline (\dmr \(0.91 \pm 0.10\) mag). SNe 2010ae and 2008ha have been classified as type Iax supernovae, and together the three either make up a distinct physical class of their own or are at the extreme low luminosity end of this diverse supernova population. The bolometric light curve is consistent with a low kinetic energy of explosion (\(E_{\rm k} \sim 10^{49}\) erg s\(^{-1}\)), a modest ejected mass (\(M_{\rm ej} \sim 0.2\) \msol) and radioactive powering by \(^{56}\)Ni (\(M_{\rm Ni} \sim 2 \times 10^{-3}\) \msol). The spectra are quite well reproduced with radiative transfer models (TARDIS) and a composition dominated by carbon, oxygen, magnesium, silicon and sulphur. Remarkably, all three of these extreme Iax events are in similar low-metallicity star-forming environments. The combination of the observational constraints for all three may be best explained by deflagrations of near \(M_{\rm Ch}\) hybrid carbon-oxygen-neon white dwarfs which have short evolutionary pathways to formation.
We report on the results of a search for CO(3-2) emission from the galaxy counterpart of a high-metallicity Damped Ly-alpha Absorber (DLA) at z=2.5832 towards the quasar Q0918+1636. We do not detect ...CO emission from the previously identified DLA galaxy counterpart. The limit we infer on M_gas / M_star is in the low end of the range found for DLA galaxies, but is still consistent with what is found for other star-forming galaxies at similar redshifts. Instead we detect CO(3-2) emission from another intensely star-forming galaxy at an impact parameter of 117 kpc from the line-of-sight to the quasar and 131 km s^-1 redshifted relative to the velocity centroid of the DLA in the quasar spectrum. In the velocity profile of the low- and high-ionisation absorption lines of the DLA there is an absorption component consistent with the redshift of this CO-emitting galaxy. It is plausible that this component is physically associated with a strong outflow in the plane of the sky from the CO-emitting galaxy. If true, this would be further evidence, in addition to what is already known from studies of Lyman-break galaxies, that galactic outflows can be traced beyond 100 kpc from star-forming galaxies. The case of this z=2.583 structure is an illustration of this in a group environment.
Here we built up a sample of 22 GRBs at redshifts \(z > 2\) observed with X-shooter to determine the abundances of hydrogen, metals, dust, and molecular species. This allows us to study the ...metallicity and dust depletion effects in the neutral ISM at high redshift and to answer the question whether (and why) there might be a lack of H\(_2\) in GRB-DLAs. We fit absorption lines and measure the column densities of different metal species as well as atomic and molecular hydrogen. The derived relative abundances are used to fit dust depletion sequences and determine the dust-to-metals ratio and the host-galaxy intrinsic visual extinction. There is no lack of H\(_2\)-bearing GRB-DLAs. We detect absorption lines from H\(_2\) in 6 out of 22 GRB afterglow spectra, with molecular fractions ranging between \(f\simeq 5\cdot10^{-5}\) and \(f\simeq 0.04\), and claim tentative detections in three other cases. The GRB-DLAs in the present sample have on average low metallicities (\(\mathrm{X/H}\approx -1.3\)), comparable to the rare population of QSO-ESDLAs (log N(HI) \(> 21.5\)). H\(_2\)-bearing GRB-DLAs are found to be associated with significant dust extinction, \(A_V > 0.1\) mag, and have dust-to-metals ratios DTM\( > 0.4\). All of these systems exhibit column densities of log N(HI) \(> 21.7\). The overall fraction of H\(_2\) detections is \(\ge 27\)% (41% including tentative detections), which is three times larger than in the general population of QSO-DLAs. For \(2<z<4\), and for log N(HI) \(> 21.7\), the H\(_2\) detection fraction is 60-80% in GRB-DLAs as well as in extremely strong QSO-DLAs. This is likely a consequence of the fact that both GRB- and QSO-DLAs with high N(HI) probe sight-lines with small impact parameters that indicate that the absorbing gas is associated with the inner regions of the absorbing galaxy, where the gas pressure is higher and the conversion of HI to H\(_2\) takes place.
Strong He II emission is produced by low-metallicity stellar populations. Here, we aim to identify and study a sample of He II \(\lambda 1640\)-emitting galaxies at redshifts of \(z \sim 2.5-5\) in ...the deep VANDELS spectroscopic survey.. We identified a total of 33 Bright He II emitters (S/N > 2.5) and 17 Faint emitters (S/N < 2.5) in the VANDELS survey and used the available deep multi-wavelength data to study their physical properties. After identifying seven potential AGNs in our sample and discarding them from further analysis, we divided the sample of \emph{Bright} emitters into 20 \emph{Narrow} (FWHM < 1000 km s\(^{-1}\)) and 6 \emph{Broad} (FWHM > 1000 km s\(^{-1}\)) He II emitters. We created stacks of Faint, Narrow, and Broad emitters and measured other rest-frame UV lines such as O III and C III in both individual galaxies and stacks. We then compared the UV line ratios with the output of stellar population-synthesis models to study the ionising properties of He II emitters. We do not see a significant difference between the stellar masses, star-formation rates, and rest-frame UV magnitudes of galaxies with He II and no He II emission. The stellar population models reproduce the observed UV line ratios from metals in a consistent manner, however they under-predict the total number of \heii ionising photons, confirming earlier studies and suggesting that additional mechanisms capable of producing He II are needed, such as X-ray binaries or stripped stars. The models favour subsolar metallicities (\(\sim0.1Z_\odot\)) and young stellar ages (\(10^6 - 10^7\) years) for the He II emitters. However, the metallicity measured for He II emitters is comparable to that of non-He II emitters at similar redshifts. We argue that galaxies with He II emission may have undergone a recent star-formation event, or may be powered by additional sources of He II ionisation.
The availability of electronic health records and access to a large number of routine measurements of serum creatinine and urinary albumin enhance the possibilities for epidemiologic research in ...kidney disease. However, the frequency of health care use and laboratory testing is determined by health status and indication, imposing certain challenges when identifying patients with kidney injury or disease, when using markers of kidney function as covariates, or when evaluating kidney outcomes. Depending on the specific research question, this may influence the interpretation, generalizability, and/or validity of study results. This review illustrates the heterogeneity of working definitions of kidney disease in the scientific literature and discusses advantages and limitations of the most commonly used approaches using 3 examples. We summarize ways to identify and overcome possible biases and conclude by proposing a framework for reporting definitions of exposures and outcomes in studies of kidney disease using routinely collected health care data.
Aims. Our aim is to estimate the intergalactic medium transmission towards UV-selected star-forming galaxies at redshift 4 and above and study the effect of the dust attenuation on these ...measurements. Methods. The ultra-violet spectrum of high redshift galaxies is a combination of their intrinsic emission and the effect of the Inter-Galactic medium (IGM) absorption along their line of sight. Using data coming from the unprecedented deep spectroscopy from the VANDELS ESO public survey carried out with the VIMOS instrument we compute both the dust extinction and the mean transmission of the IGM as well as its scatter from a set of 281 galaxies at z>3.87. Because of a degeneracy between the dust content of the galaxy and the IGM, we first estimate the stellar dust extinction parameter E(B-V) and study the result as a function of the dust prescription. Using these measurements as constraint for the spectral fit we estimate the IGM transmission Tr(Lyalpha). Both photometric and spectroscopic SED fitting are done using the SPectroscopy And photometRy fiTting tool for Astronomical aNalysis (SPARTAN) that is able to fit the spectral continuum of the galaxies as well as photometric data. Results. Using the classical Calzetti's attenuation law we find that E(B-V) goes from 0.11 at z=3.99 to 0.08 at z=5.15. These results are in very good agreement with previous measurements from the literature. We estimate the IGM transmission and find that the transmission is decreasing with increasing redshift from Tr(Lyalpha)=0.53 at z=3.99 to 0.28 at z=5.15. We also find a large standard deviation around the average transmission that is more than 0.1 at every redshift. Our results are in very good agreement with both previous measurements from AGN studies and with theoretical models.
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